Table of Content

15 November 2022, Volume 41 Issue 11

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Research Progress on Preparation Technology of Long Wave Infrared Chalcogenide Glass

ZHAO Hua, ZHANG Huihui, ZU Chengkui, LIU Yonghua, ZHOU Peng, ZHANG Baodong, PAN Feng, HE Kun, HAN Bin

2022, 41(11):  3719-3732. 

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Chalcogenide glass has the advantages of low refractive index temperature coefficient, wide spectral transmission range, good optical uniformity, adjustable performance and easy processing, etc. Chalcogenide glass is regarded as the core component material of new generation temperature adaptive infrared thermal imaging system, and has a broad application prospect in many fields such as infrared tracking, infrared guidance, security monitoring, driving assistance and so on. However, Chalcogenide glass itself is a brittle material, and has some performance shortcomings such as low softening temperature, poor temperature resistance, lack of plastic deformation and sensitivity of strength to micro-defects, etc. In order to solve the demand for infrared materials in extreme service environment or special application, the research on preparation technology of chalcogenide glass mainly involves three aspects: (1) Design and develop the preparation method of large size and high purity chalcogenide glass. (2) Research on atmosphere melting technology to meet the engineering application requirements of large size chalcogenide glass, and then improve the environmental adaptability of window materials. (3) High energy ball milling, hot-pressing and other methods are introduced into the preparation of chalcogenide glass-ceramics to expand the optional range of infrared optical materials and improve the extreme environmental adaptability of chalcogenide glass materials. Based on the above three aspects, the research progress on the preparation technology of chalcogenide glass was reviewed.

Research Progress on Er ∶ZBLAN Mid-Infrared Fiber Lasers Emitting at 2.8 μm

ZHAO Wenkai, WANG Yuchen, LI Yanchao, ZHANG Longfei, LIU Ruite, ZHOU Zhiming, ZHANG Long, JIANG Yiguang

2022, 41(11):  3733-3744. 

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The mid-infrared (MIR) region plays an important role in the fields of environmental monitoring, material processing, surgery and defense. Currently, low-loss high-concentration Er³⁺-doped ZBLAN (Er ∶ZBLAN) fiber is one of the main promising gain media for 3 μm MIR laser sources. Er ∶ZBLAN fiber lasers have the advantages of being easily integrated, highly efficient and directly diode-pumped in comparison to other 3 μm-class lasers. With improving performance, Er ∶ZBLAN lasers are expected to reach maturity and commercialized at wavelength of near 3 μm firstly. The working principle and status of Er ∶ZBLAN fiber laser were briefly described in this paper, and the existing problems of three different Er ∶ZBLAN fiber lasers were analyzed and summarized. Finally, the development trends were also prospected.

Research Progress on Preparation Method and Property of Metal Coated Optical Fibers

ZHAO Jinkai, WANG Hong, JIA Jinsheng, SUN Yong, KONG Zhuang, LIU Bo, YANG Liangliang, WANG Yiwei

2022, 41(11):  3745-3755. 

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Metal coated optical fibers are suitable for detection and information transmission in extreme environments. At present, the research on metal coated optical fibers mainly focuses on: (1) the different preparation methods, including electroless plating, electroplating, sputtering, evaporation and molten metal method, and comparing the effects of different process parameters on metal coating quality; (2) characterization and evaluation methods of metal-coated optical fiber coating quality, mechanical properties, and macrobending loss performance; (3) application scenarios of metal coated optical fibers. This paper reviewed the research progress of the preparation methods and properties, summarized the current problems, and provided references for the scientific research and development of metal coated optical fibers.

Exploration of Chalcogenide Glass Fiber Preparation Method Based on Pulse Injection Technology

GUO Yongchang, LI Can, FENG Shaowei, TAO Haizheng, WANG Hui, LI Jianqiang

2022, 41(11):  3756-3760. 

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Due to their unique infrared optical properties, such as excellent transmission in infrared band, low phonon energy and good chemical stability, chalcogenide glass fiber has promising applications in many fields such as infrared imaging, laser transmission and sensing. At present, the preparation of chalcogenide glass optical fiber mainly includes double-crucible method and rod-in-tube method. The double-crucible method is complicated, and the rod-in-tube method needs to prepare high-quality preforms in advance. In addition, both methods require high crystallization resistance of glass, which limits the development of new materials for chalcogenide glass optical fiber. In this work, the pulse injection technology was innovatively introduced into the field of chalcogenide glass fiber preparation, and the feasibility of this method for glass fiber preparation by drawing chalcogenide glass fiber core was explored. By applying continuous pulse perturbation to glass melt, a continuous jet was generated at the bottom hole of the crucible and solidified during falling, resulting in glass fiber core. Using this method, a chalcogenide glass fiber with the composition of Ge₂₈Sb₁₂Se₆₀ was successfully prepared. The pulse injection method is simple and easy to operate, and the pulling of chalcogenide glass fiber is achieved by continuous and regular pulses and pressure difference between the inside and outside of crucible, which has more abundant control means than traditional gravity-based glass fiber pulling. This method provides a potential reference for the preparation of new chalcogenide glass fiber.

Preparation of As₂Se₃ Chalcogenide Glasses by Powder Hot Pressing Method

MA Cheng, YANG Anping, LI Lei, CHEN Qian, TIAN Kangzhen, LIU Zijun, SHEN Xiang, YANG Zhiyong

2022, 41(11):  3761-3767. 

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This research attempts to recycle the bulk glass waste produced in the production of As₂Se₃ infrared chalcogenide lenses. First, the cleaned bulk glass waste was ground into powder, and then the powder hot pressing technique was used to achieve the high optical quality As₂Se₃ glass disks. The effects of powder size and hot pressing parameters on the optical properties of hot-pressed As₂Se₃ glasses were studied, the properties of As₂Se₃ glasses prepared by powder hot pressing method and melt quenching method were compared, and the feasibility of preparing infrared chalcogenide glass by powder hot pressing technique was evaluated. The experimental results show that the mean particle size of As₂Se₃ glass powder decreases gradually with the prolongation of milling time, and the distribution of particle size tends to be more uniform. Using the powder with mean particle size of 9.7 μm (the milling time is 10 min), a glass disk with compactness of 99.8% is obtained under the conditions of pressure of 40 MPa, hot pressing temperature of 250 ℃ and holding time of 10 min. The refractive index of the hot-pressed glass is close to that of the glass prepared by melt quenching method (the difference is only 0.003 at 10 μm), and its transmittance is as high as 61% at 10 μm (the theoretical transmittance is 63.7%). By further improving the purity and size uniformity of glass powder, it is expected to prepare hot-pressed glass with the same performance as the glass prepared by melt quenching method.

Effect of Nb₂O₅ on Spectral Properties of Nd³⁺ Doped Germanate Glass

JIANG Xiaoqi, SUN Yan, WANG Yafei, WANG Xin, CHEN Shubin, HU Lili, SHI Yanchun, GUO Aimin

2022, 41(11):  3768-3776. 

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Blue laser has a wide range of application prospects in the fields of color laser display, high-density optical storage, exploration of marine resource, underwater communication and biomedical sciences, etc. However, the relatively mature Yb³⁺ doped fiber laser can only obtain blue green (~490 nm) laser after frequency doubling. Therefore, it is an urgent issue to obtain a pure blue laser close to 450 nm. The 0.9 μm fluorescence generated by the ⁴F_3/2→⁴I_9/2 level transition of Nd³⁺ can obtain the pure blue laser output of ~450 nm after frequency doubling, which has excellent application potential in the field of blue laser. However, the fluorescence generated by this transition occupies a low fluorescence branching raito. In this paper, the absorption spectrum, fluorescence spectrum and fluorescence lifetime of 1% (mass fraction) Nd₂O₃ doped 50GeO₂-(20-x)PbO-15BaO-15ZnO-xNb₂O₅ (x%=0%, 2.5%, 5%, 10%, 15%,mole fraction) glass were systematically studied, and the corresponding Judd-Ofelt intensity parameters and gain bandwidth were calculated. It is found that the 900 nm absorption cross section, emission cross section, effective linewidth and fluorescence branching ratio of Nd³⁺ increase with the doping of Nb₂O₅. When the concentration of Nb₂O₅ is 10% (mole fraction), Judd-Ofelt intensity parameter Ω₂=5.91×10^-20 cm², the spectral quality parameter χ=1.01, and the fluorescence branching ratio is 42.9%. In summary, 0.9 μm fluorescence branching ratio of Nd³⁺ can be raised by Nb₂O₅, so as to obtain pure blue light (450 nm) by frequency doubling, which is beneficial to the development and application of blue laser.

Coherent Silica Fiber Bundles with Ultra-High Resolution

XU Yantao, GUO Haitao, HOU Chaoqi, CUI Xiaoxia, GAO Song, ZHANG Yan, SHE Shengfei

2022, 41(11):  3777-3780. 

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Coherent silica fiber bundles have important applications in medical diagnosis, industrial equipment defects detection, high-voltage transformer winding monitoring, and large field optical systems. The sol-gel method is used to introduce absorbent into pixel monofilament gap, which successfully solves the problem of crosstalk in bundles. Silica fiber bundles with 600 μm outer diameter, 15 000 pixels, 4.4 μm pixel diameter, and resolution of 113 lp/mm were prepared by one-step multiple-fiber process. The results show that there are no dark or broken pixels, no distortion in bundles and the image is clear, which means the coherent silica fiber bundles meet the commercial use requirements.

Ultrafast Laser Direct Writing of Nanocrystals in Glass and Applications

LI Xinkuo, TAN Dezhi, LIU Yi, SUN Ke, ZHU Tiejun, QIU Jianrong

2022, 41(11):  3781-3794. 

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Ultrafast laser direct writing (ULDW) can selectively induce three-dimensional modifications inside transparent materials and has been widely used to write crystallite structures in glass, which enables the preparation of various optoelectronic devices for the optical storage, waveguide lasers, photonic circuits and integrated photonic chips. The principle of ultrafast laser induced crystallization in glass and the generation mechanism of self-organized periodic structures were briefly summarized. And the recent research progress on ultrafast laser induced three-dimensional crystallization in glass, and the control of crystal morphology, structures and optical properties via controlling the laser parameters and glass composition were reviewed. The applications in nonlinear devices, optical storage, and lasers were also discussed.

Research Progress on High-Strength Li₂O-Al₂O₃-SiO₂ System Glass-Ceramics

LI Weichang, WANG Xin, HU Lili, CHEN Shubin, CHEN Huiyu, ZHANG Xufeng, JIANG Xiaoqi

2022, 41(11):  3795-3805. 

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Li₂O-Al₂O₃-SiO₂(LAS) system glass-ceramics have been widely used in recent years, as their excellent mechanical and optical properties. In this work, the precipitated crystal phase, preparation technique and application of LAS glass-ceramics were introduced. In view of the current urgent demand for high-hard scratch-resistant glass, the current research progress on LAS glass-ceramics strengthening and toughening technology and surface enhancement methods was emphatically expounded. This paper plays an important guiding role in the development of high-strength LAS glass-ceramics in the future.

Exploration on Glass Transition and Crystallization Behavior in Aluminosilicate Glasses with Substitution of MgO by ZnO

HUANG Xin, WANG Bingbing, GU Shaoxuan, QIAO Ang, TAO Haizheng

2022, 41(11):  3806-3812. 

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As an important transparent glass ceramic system, ZnO-MgO-Al₂O₃-SiO₂ glass exhibits excellent mechanical and optical properties. Numerous studies have focused on the mechanism of controllable nucleation and crystal growth, but the physical mechanism of the substitution of MgO by ZnO on glass transition and crystallization behavior of aluminosilicate glass is not clear. In this work, the effect of the substitution of MgO by ZnO on the glass transition and crystallization behaviors of xZnO·(11-x)MgO·22Al₂O₃·67SiO₂ (x%=0%, 2.2%, 5.5%, 8.8%, 11.0%, mole fraction) glasses was studied. The results show that the glass transition temperature of studied glasses decreases with the substitution of MgO by ZnO, and it can be ascribed to the decrease of the average bonding strength of the glass network, which is induced by the weaker field strength and shielding effect of an extra electron layer in Zn²⁺ compared to Mg²⁺. The crystallization phases transfer from singe mullite to the mixture of mullite and zinc aluminate gahnite due to the addition of ZnO causing the phase separation of aluminosilicate glass. The substitution of MgO by ZnO causes a steeper viscosity curve around crystallization temperature and decreases the crystallization activation energy of the glasses, resulting in the shift of crystallization peaks to lower temperature.

Crystallization and Mechanical Properties of Li₂O-Al₂O₃-SiO₂ Glass Ceramics with High Strength and Semi-Transparency

ZHOU Weiwei, CHEN Bao, HAO Zhenbang, HE Guangyuan, ZHU Kaidi, LIU Jingzhong, ZHANG Fujun, ZHANG Jihong

2022, 41(11):  3813-3818. 

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It's an urgent problem to improve the strength of Li₂O-Al₂O₃-SiO₂ glass ceramics by glass composition design and crystallization process control. In this paper, Li₂O-Al₂O₃-SiO₂ glass with specific composition was prepared by melt-quenching method, and high strength semi-translucent glass ceramics were prepared by two-step heat treatment. Differential scanning thermal analysis shows that the glass transition temperature is 532 ℃ and there are multiple crystallization peaks. After heat treatment, X-ray diffraction patterns prove that Li₂Si₂O₅, LiAlSi₃O₈, LiAlSi₄O₁₀ as the main crystal phases are precipitated in the glass, petalite crystals gradually changes into spodumene crystal phases with the increase of heat treatment temperatures or durations, and average crystal sizes grow from 70 nm (heat treatment parameters: 750 ℃,0.5 h and 780 ℃, 10 h) to 340 nm (heat treatment parameters: 820 ℃, 0.5 h and 850 ℃, 4 h). The glass ceramics change from translucent to opacities. Glass ceramics have excellent mechanical properties, the maximum Vickers hardness is 9.15 GPa, the maximum ring-on-ring load can reach 1 335 N, and the maximum simulated whole machine drop height can reach 162 cm. The glass ceramics can be used as backplane protection glass for mobile phone devices.

Crystallization Kinetics of Lithium Aluminum Silicate Transparent Glass-Ceramics

PENG Zhigang, YUAN Jian, DU Xiaoou, ZHENG Weihong, ZHANG Maosen, XUE Ruifeng, SHI Lianying

2022, 41(11):  3819-3825. 

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The crystallization kinetics of lithium aluminum silicate Li₂O-Al₂O₃-SiO₂-ZrO₂-P₂O₅ transparent glass-ceramics was analyzed by using the classical equation (Johnson-Mehl-Avrami). The influence of crystallization temperature on the crystallization behavior of glass was studied by DSC, XRD and SEM. The results show that Li₂Si₂O₅ and Li₂SiO₃ precipitate at lower initial crystallization temperature. With the increase of crystallization temperature, the main crystal phase changes to LiAlSi₄O₁₀, Li₂SiO₃ disappears and the crystal size decreases, and the transmittance of glass-ceramics increases from 89.3% to 90.6% at 550 nm. The activation energies of crystallization of Li₂Si₂O₅ and LiAlSi₄O₁₀ are calculated by Kissinger method to be 349.5 kJ/mol and 184.2 kJ/mol, and the average crystal growth indices are 3.05 and 1.42, respectively.

Phase Boundary and Energy Storage Performance of La₂O₃ Doped SiO₂-B₂O₃-Nb₂O₅ Complex Phase Glass-Ceramics

GUO Hongwei, BAI Yun, CHI Longxing, ZHAO Zhilong, LIU Shuai, WANG Yi, LI Rongyue

2022, 41(11):  3826-3833. 

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La₂O₃ doped SiO₂-B₂O₃-Nb₂O₅ (SBN) complex phase glass-ceramics were prepared by controlled crystallization method. The effects of La₂O₃ doping on structure and energy storage performance of SBN complex phase glass-ceramics were characterized by DSC, Raman, XRD, SEM, ferroelectric and dielectric tests. The results show that La₂O₃ doping can effectively improve the thermal stability of complex phase glass-ceramics. With the increase of La₂O₃ content, the crystallization barrier of the system increases, the thermal expansion coefficient decreases first and then increases,the valence bond vibration intensifies, the dielectric constant increases first and then decreases, and the dielectric loss decreases first and then increases. When doped with 1.00% (mole fraction) La₂O₃, the energy storage density and energy storage efficiency of complex phase glass-ceramics under 40 kV/cm are the highest, which are 0.031 J·cm^-3 and 77.6%, respectively. The energy storage performance is mainly evaluated by the synergistic effect of dielectric constant and breakdown field strength. La₂O₃ can improve the dielectric constant by improving structure stability and reducing dielectric loss. When La₂O₃ is introduced into the system, it is in the voids of glass network, which can effectively enhance the breakdown resistance of material. The complex phase glass-ceramic structure can increase structural disorder, thereby reducing relaxation loss and effectively improving the energy storage performance of material.

Preparation of Fluorapatite Based Glass-Ceramics from Fluorite Tailings and Waste Glass by Sintering Method

WANG Rui, LI Hongwei, ZHAO Wei, GUO Hongwei

2022, 41(11):  3834-3843. 

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In this work, glass-ceramics were prepared by sintering method with fluorite tailings (FT) and waste glass (WG) as raw materials and calcium silicate (CS) as additive. The crystallization characteristics and morphology of glass-ceramics were characterized by X-ray diffracometer and scanning electron microscope. The size and number of grains were counted by Image Pro Plus. The changes in the phase and liquid phase of high temperature during the preparation of glass-ceramics under different ratios were characterized by Factsage software. And the flexural strength, acid and alkali resistance of glass-ceramics were tested. The results show that the good-quality glass-ceramicswith fluorapatite (Ca₅P₃O₁₂F) as the main crystalline phase are obtained in the temperature range of 1 060 ℃ to 1 180 ℃. With the increase of CS ratio, the grain refinement of the main crystalline phase—fluorapatite is obtained, which is beneficial to improve the mechanical property of glass-ceramics. At a ratio (mass fraction) of 30%FT, 60%WG and 10%CS, glass-ceramics have not only good strength but also good acid and alkali resistance. The glass-ceramics designed in this work provide an economic and novel way of recycling FT, which is of great practical significance to reduce the production cost of glass-ceramics and promote the development of recycling economy of solid waste resource.

Effect of Fe₂O₃ on Crystallization Behavior of CaO-MgO-Al₂O₃-SiO₂ Glass-Ceramics Based on Copper Tailings

SHI Linyun, XU Yuhua, WEI Qi

2022, 41(11):  3844-3851. 

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CaO-MgO-Al₂O₃-SiO₂ (CMAS) glass-ceramics were prepared by melting method using copper tailings as main raw material. The crystallization behavior of fine-grained copper tailings based CMAS glass-ceramics was optimized by adding Fe₂O₃ crystal nucleation agent. The effect of nucleation agent content on the crystallization behavior and physical properties of fine-grained copper tailings based CMAS glass-ceramics was studied by DSC, XRD and SEM, and the crystallization kinetics parameters were calculated by Ozawa-Chen method. The results show that when the amount of Fe₂O₃ crystal nucleation agent is more than 3.72%(mass fraction), the glass-ceramics prepared from fine-grained copper tailings can achieve overall crystallization. The precipitation of pyroxene phase is the result of coordination of Fe and Mg elements in glass phase into [Si(Al)O₄] tetrahedral lattice. In addition, the increase of Fe³⁺ is conducive to the precipitation of pyroxene phase and reduces crystallization activation energy. The crystallization behavior and mechanical properties of fine-grained copper tailings based glass-ceramics are optimized by Fe₂O₃ crystal nucleation agent.

Effects of Additives on Crystallization Behavior and Properties of Glass-Ceramics from Copper Slag Reduction Tailings

LUO Yanheng, MA Guojun, LI Zhi, ZHENG Dingli, ZHANG Xiang, ZHU Junlin

2022, 41(11):  3852-3860. 

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The chemical composition of copper slag reduction tailings is similar to that of CaO-Al₂O₃-SiO₂ glass-ceramics. The preparation of glass-ceramics with copper slag reduction tailings as the main raw material by melting method provides an effective way for the efficient utilization of copper slag. The effects of different additives (B₂O₃, CaF₂, TiO₂ and Cr₂O₃) on the phase composition, flexural strength, bulk density, water absorption and apparent porosity of glass-ceramics were studied by DSC, XRD and SEM-EDS. The experimental results show that no matter which additive is added, the glass-ceramics precipitate anorthite and gehlenite with good mechanical properties, and the crystal crystallization mode transforms into overall crystallization. Adding B₂O₃ makes the best performance of glass-ceramics, followed by TiO₂ and CaF₂.

Effect of CaO Content on Crystalline Phases and Chemical Stability of Lanthanum Borosilicate Glass-Ceramics

FU Maoyang, LIAO Qilong, WANG Fu, XU Youli, HE Zexu, ZHU Hanzhen

2022, 41(11):  3861-3869. 

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The Na₂O-CaO-La₂O₃-B₂O₃-SiO₂ glass were prepared by melt-quenching method. Then, the silicate oxyapatite borosilicate glass-ceramics were obtained by heat treatment of the prepared glass. After that, the X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and the product consistency test (PCT) were used to explore the effect of CaO substitution for SiO₂ on phases, microstructure and chemical stability of borosilicate glass-ceramics. The results show that with the increase of CaO content, the diffraction peaks of silicate oxyapatite crystalline phase are enhanced, and the others are weakened until disappearing. When the mole fraction of CaO is 15%, only the CaLa₄(SiO₄)₃O crystalline phase is detected in the glass-ceramics samples. The crystalline phases types, shapes, sizes and distributions of glass-ceramics are affected by CaO content, and the cluster and growth of ceramics crystalline phases are caused by the change of CaO content. After immersing by the method of PCT for 28 d, the normalized leaching rates (g·m^-2·d^-1) of Si, Ca and La of all samples remain below the order of 10^-3, indicating that the glass-ceramics samples have excellent chemical stability. In addition, the glass-ceramics samples containing the CaO mole fraction of 15% exhibit the best chemical stability. The results show that the borosilicate glass-ceramics containing silicate oxyapatite are potential substrates for immobilization high-level radioactive wastes containing La-rich and some actinide rich.

Heat Treatment Process Optimization of Ultra-Low Expansion Glass-Ceramics

ZHAO Chunxia, FAN Shigang, LIU Jie, HE Can, LI Yue

2022, 41(11):  3870-3876. 

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Li₂O-Al₂O₃-SiO₂ system transparent glass was prepared by melting method, and ultra-low expansion glass-ceramics were obtained by heat treatment with TiO₂, ZrO₂ and P₂O₅ as composite nucleating agents. The effects of heat treatment parameters on thermal expansioncoefficient of glass-ceramics were studied by orthogonal experiments. The optimal heat treatment parameters were obtained through calculation and analysis, that is, the nucleation temperature is 600 ℃, the nucleation time is 3 h, the crystallization temperature is 820 ℃, and the crystallization time is 5 h. The main crystalline phase of glass-ceramics obtained under this heat treatment process is β-quartz solid solution, and the thermal expansioncoefficient is 1.6×10^-8 ℃^-1. The crystallization and microstructure of glass-ceramics were studied by means of differential thermal analysis, X-ray diffraction analysis, scanning electron microscopy analysis and transmission electron microscopy analysis. The relationship between heat treatment process, thermal expansion properties and microstructure of glass-ceramics was analyzed. The results show that the thermal expansion coefficient of glass-ceramics is determined by the type and content of crystalline phase, and the size and content of crystalline phase which formed inside glass-ceramics are closely related to heat treatment process.

Internet-Based Intelligent Integrated Service Mode for EPC Building Materials Industry

MA Liyun, GUAN Min, AI Xiaojing, YU Tao, GAI Linlin, CHANG Zheng, SHENG Jiacheng, HU Kuangyi, CHU Jingyuan, ZHANG Danlei

2022, 41(11):  3877-3885. 

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In response to meeting the construction needs of the new intelligent production lines, with the goal of realizing fully digitization, automation, knowledge and intelligence, China Triumph International Engineering Co., Ltd. has designed and researched an internet-based intelligent integrated service model for the engineering procurement construction (EPC) building materials industry. A large number of principles of industrial technology, industry knowledge and basic model integrating are regularized, software-based and modularized, and encapsulated into reusable and flexible microservices to achieve rapidly application deployment and network collaboration of industrial application (APP). The service model supports basic management, such as computing, storage and service, and at the same time, the data of production process is managed, controlled and analyzed to realize the coordinated management of the entire production process including equipment condition monitoring, fault diagnosis, prediction and early warning, quality control, process control, operation and maintenance. A number of intelligent plant system solutions have been formed, and relevant results have been applied in several demonstration projects. The development and application of the internet-based intelligent integrated service model for the EPC building materials industry accelerates the transformation of enterprises and the implementation of the intelligent service strategy for the building materials industry, which has played a good demonstration role and has promotion value.

Thermo-Chemical Regeneration Design for Energy Saving and Emission Reduction of Glass Industry Furnace

ZENG Hongjie, ZHANG Gang, MA Liyun, GUAN Min, ZHOU Wencai, WANG Chuanshen, ZUO Zefang

2022, 41(11):  3886-3892. 

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Fuel combustion is the main source of carbon emission in glass industry. Thermo-chemical regeneration technology can significantly reduce the melting energy consumption and carbon emission of glass furnace. In this paper, the feasibility of thermo-chemical reforming reaction in glass furnace, the effects of design parameters on thermo-chemical reforming reaction, the effect of gas conversion on energy saving efficiency of glass furnace and the effect of thermo-chemical reforming reaction time on gas conversion and yield were studied through calculation and simulation. The results show that the spontaneous reaction temperature of methane and water vapour is more than 617.82 ℃, and the spontaneous reaction temperature of methane and carbon dioxide is more than 641.27 ℃. In addition, when the reforming reaction temperature is greater than 1 000 ℃, the reaction time is greater than 10 s, and the flow ratio (molar ratio) of methane to furnace waste gas is close to 1, the thermo-chemical reforming reaction can be fully carried out.

Research Status and Development of Sealing Technology in Vacuum Glass

LI Shenhou, LOU Jing, WANG Congxiao, YANG Jianqiang, LI Jiang, NIU Hao, YANG Yu, SONG Xiaozhen

2022, 41(11):  3893-3900. 

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Due to excellent properties such as thermal insulation, sound insulation, lightness and anti-condensation, vacuum glass has been gradually used in energy-saving building, household appliances, traffic, agriculture, etc. Especially, the vacuum glass shows broad development prospects in the field of energy-saving buildings. In this paper, the development history of vacuum glass was reviewed. Then, the research foundation of vacuum glass, the major breakthrough progress and industrialization status of industrialization technology were introduced. Moreover, the sealing materials and sealing technologies of vacuum glass and the latest research progress were mainly described. Finally, the future development of sealing materials and sealing technologies in vacuum glass were prospected in order to provide reference for the basic research and industrial application of high performance vacuum glass.

Numerical Simulation of Ultra-Large-Scale Float Glass Furnace with Two Working Ends

YI Li, HAN Jianjun, WANG Guirong, LI Luyao, RUAN Jian, CHEN Decheng, WANG Wentian

2022, 41(11):  3901-3909. 

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The technology of one furnace with two working ends for float glass is significant for upgrading and transformation of float glass industry and achieving carbon peaking and carbon neutrality goals in China. In this study, a numerical simulation of a 1 250 t/d ultra-large-scale float glass furnace with two asymmetric working ends was carried out by using Glass Furnace Model software, and the temperature distribution and glass melt flow character were analyzed. The influence of an eccentric structure design for working ends on glass melt temperature homogeneity and glass melt flow stability at the exits was studied by analyzing temperature contour and melt flow pattern, and comparing trajectories of fastest particles, minimum residence time and average residence time of particles. The results show that the temperature of glass melt at the entrance of branch working ends decreases when the proportion of back flow feeding into the branch working ends increases. Increasing the length of channel connecting the neck and branch working ends leads a lower glass melt temperature at the branch line exit. It is clear that an appropriate eccentric structure design for working ends is beneficial for minimizing the difference of residence time in furnace between glass melt leaving through different working ends. It is also helpful for decreasing the temperature difference of glass melt in horizontal direction during homogenizing and cooling stages as well as increasing the flow stability of glass melt in both of the two working ends.

Study of Glass Spray Tempering Process

SHI Faxiang, ZHAO Julong, LIU Fengxiao, DUAN Runze, TIAN Liang

2022, 41(11):  3910-3917. 

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The spray tempering process is theoretically more energy-efficient than the air-cooled tempering process. In order to investigate the actual energy-saving effect of the spray tempering process, the plate glass with dimension of 40 mm×40 mm×5 mm were used for air-cooled tempering and spray tempering tests. The results show that compared with air-cooled tempering process, the spray tempering process saves at least 25.06% energy during cooling. The spray tempering process improves the tempering degree of glass, that is, the particle number of broken increases by at least 8.91%, the surface compressive stress increases by at least 12.12%. With the increase of mist load fraction, the cooling time decreases, and the energy saving effect and tempering degree increase.

Deformation Characteristics of Tempered Vacuum Glass under Temperature Difference

GAO Shuai, YUE Gaowei, LIN Haixiao, LI Minmin, LIU Hui

2022, 41(11):  3918-3924. 

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The temperature difference between two sides of tempered vacuum glass is one of the important reasons for its bending failure. The deformation characteristics of tempered vacuum glass (TVG) were tested at various temperature difference and in various diameters, and determined by temperature difference deformation tests and finite element modelin (FEM) analysis. The findings demonstrate that the maximum deformation of TVG is in the center of the glass and gradually decreases to the periphery. Curvature radius of the sphere created by temperature difference between two sides of TVG is directly proportional to the thickness of the tempered glass, but inversely proportional to temperature difference between the two sides as well as to the linear expansion coefficient of glass. Glass size, temperature difference and curvature radius are all positivly correlated with the deformation of TVG. With the same temperature difference and different size of TVG, its deformation increases with the increase of the long side size of tempered glass. The larger the long edge size of TVG, the more significantly the deformation is affected by temperature difference. Moreover, a useful approach for the deformation prediction of TVG with different diameters under temperature difference is provided by the FEM analysis results, which is in good agreement with the experimental findings and where the relative error is less than 5%.

Research Status and Development Trend of Alkali and Alkaline Earth Aluminosilicate Glass-Ceramics Cover Glass

LIU Honggang, PING Wenliang, LI Sheng, KANG Qingwei, CHEN Jianhao, XIAO Zifan, DONG Guoping

2022, 41(11):  3925-3936. 

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The development of mobile communications has intrigued the soaring demand for mobile electronic devices, causing prosperity in the corresponding cover glass industry. Glass manufacturers have launched their quality products based on traditional aluminosilicate glass, but it is becoming difficult to further improve the performance of glass through traditional methods such as adjusting formulas and improving chemical tempering systems, etc. Recently, transparent glass-ceramics, which enhances the mechanical properties of glass through crystallization, has attracted extensive attention in the industry. This paper reviewed the mature chemical tempering process and introduced its application in high-alkali aluminosilicate glass. Then transparent aluminosilicate glass-ceramics applied to cover glass were introduced. Finally, the research and development trend of traditional toughened glass and new transparent glass-ceramics were summarized.

Review of Ultrathin High Strength Screen Protection Glass

TIAN Yingliang, LIU Xinhao, LI Junjie, WANG Mingzhong, WEN Yulin, ZHAO Zhiyong

2022, 41(11):  3937-3944. 

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Ultrathin high strength screen protection glass is an important protective material for touched display products, and is currently a popular glass variety. After years of technical development and product iterative update, the ultrathin screen protection glass has been developed into a series of alkali-aluminosilicate products with different composition characteristics. In this paper, the domestic and foreign screen protection glass products and iterative process were combed, and the chemical composition characteristics of different types of alkali-aluminosilicate glass products were summarized. Meanwhile, the chemical strengthening process technology corresponding to different products were analyzed, the research status of high strength transparent glass-ceramics at home and abroad were discussed, and the future development direction of glass-ceramics was also prospected. Thus, this paper provides a reference for the research and development of screen protection glass.

Effect of Na⁺ Concentration on Properties of Chemical Strengthened Sodium Aluminosilicate Glass

TIAN Haodong, XU Chi, WU Zhiyuan, ZHOU Shaojun, ZU Chengkui

2022, 41(11):  3945-3951. 

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Marginal Na⁺ concentration in molten salt has not significant effects on ion-exchange process of glass. However, when the Na⁺ concentration in the molten salt continues to increase, the performance of chemical strengthened sodium aluminosilicate glass begins to be affected. To overcome this issue, one-step ion-exchange process was developed to reaserch chemical strengthened sodium aluminosilicate glass with different thickness. Effect of Na⁺ concentration in molten salt on surface compressive stress, depth of layer and bending strength of chemical strengthened sodium aluminosilicate glass were investigated. The results demonstrate that the surface compressive stress and bending strength of chemical strengthened sodium aluminosilicate glass decrease when the Na⁺ concentration in molten salt increases. The bending strength decreases by up to 175 MPa, while the surface compressive stress decreases by 57.4 MPa. The change of Na⁺ concentration in molten salt has not obviously effects on the depth of layer and visible light transmittance of chemical strengthened sodium aluminosilicate glass.

Effects of Different Refining Agents on Clarification Effect of Neutral Pharmaceutical Glass

ZHANG Xiaoyu, LI Changqing, ZHAO Fengyang, SHI Lifen, ZHONG Zhaojin, GAO Qiang

2022, 41(11):  3952-3959. 

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Due to its excellent chemical stability and thermal stability, neutral pharmaceutical glass is widely used in pharmaceutical, food and other packaging fields. In this paper, the effects of oxide refining agent CeO₂, halide refining agent NaCl, and compound refining agent NaCl-CeO₂ and NaCl-CeO₂-NaNO₃ on the clarification effect of neutral pharmaceutical glass were studied. The changes of area fraction, number of bubbles, and mean bubble size were quantitatively analyzed, and the refining agent suitable for neutral medical glass was explored. The research results show that after adding NaCl-CeO₂-NaNO₃ to the neutral pharmaceutical glass liquid, the area fraction and number of bubbles are smaller, and the mean bubble size is larger. Thus, the clarification effect of adding NaCl-CeO₂-NaNO₃ is better than adding NaCl and CeO₂. When 0.4% (mass fraction) NaCl-0.20% (mass fraction) CeO₂-0.005 0% (mass fraction) NaNO₃ is added, within 3 h after the temperature raising to 1 550 ℃, the area fraction of neutral pharmaceutical glass is reduced to 0.6%, the number of bubbles is reduced to 3, and the mean bubble size is 0.60 mm, the clarification effect is better.

Migration Characteristics on Inner Surface of Neutral Borosilicate Glass Tube Vials

TIAN Yingliang, WEN Yulin, WANG Fan, WANG Hua, WANG Huanyi, ZHAO Zhiyong, SUN Shibing

2022, 41(11):  3960-3968. 

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In this paper, neutral borosilicate glass tube vials were taken as research object, and ICP-AES was used as research method. By changing liquid medicine concentration, liquid medicine pH value, liquid medicine storage time, glass bottle specification, the migration law of Al³⁺, B³⁺, Ca²⁺, K⁺, Na⁺, Si⁴⁺ on the inner surface of glass bottle were explored, and the inner surface erosion of glass bottle was observed by SEM. The results show that with the prolongation of storage time, the erosion degree of the inner surface of glass bottle increases. When storage time is 28 d, the migration concentration of K⁺ and Na⁺ decreases, the migration concentration of Al³⁺, B³⁺, Ca²⁺, Si⁴⁺ increases, and the peeling phenomenon occurs. The smaller the glass bottle specification is, the greater the migration concentration of ions and the erosion degree of the inner surface of glass bottle are. The smaller the liquid medicine concentration is, the smaller the concentration of ions and the erosion degree of the inner surface of glass bottle are. Both acidic and alkaline solution make the erosion degree of the inner surface of glass bottle increase, and alkaline liquid on the inner surface of glass bottle erosion is greater.

Effect of CaO Content on CBAS Glass/Al₂O₃ Low Temperature Co-Fired Ceramic

LI Zijie, HE Feng, FAN Yunfei, XIE Junlin, MEI Shuxia, YANG Hu, LIU Xiaoqing

2022, 41(11):  3969-3978. 

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In this paper, the structure and performance effects of CaO content on CaO-B₂O₃-Al₂O₃-SiO₂ (CBAS) glass/Al₂O₃ low temperature co-fired ceramic were mainly studied. The structure of glass and low temperature co-fired ceramic was characterized and analyzed by DSC, FTIR, XRD, SEM and other test methods. The research results show that when the CaO content is lower than 40% (mass fraction, the same bellow), the increase of free oxygen introduced by CaO destroys the glass network structure and reduces the glass viscosity. When the CaO content is greater than 40%, Ca²⁺ forms larger anion units with [SiO₄] tetrahedra, which improves glass viscosity and glass transition temperature. The precipitation of CaSiO₃ and Ca₂SiO₄ and the transition from CaSiO₃ to Ca₂SiO₄ are facilitated by CaO. As the CaO content increases, the denseness of the ceramics increases first and then decreases, and the crystalline phase size gradually increases, which leads to an increase in the density, flexural strength and dielectric constant of the ceramic and then a decrease. When the CaO content is 40%, the sample achieves the best performance with the maximum density of 2.94 g/cm³, the flexural strength of 153.44 MPa, and the dielectric constant of 9.69.

Effects of Dispersants on Rheological Properties of LTCC Casting Slurry

LYU Zibin, GUO Enxia, HAI Yun, CAO Yu, LYU Jinyu, XU Bo, HAN Bin, ZU Chengkui

2022, 41(11):  3979-3989. 

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In this paper, the effects of castor oil, BYK-22552, polyvinylpyrrolidone (PVP) and TEGO-700 on the dispersion of CaO-B₂O₃-La₂O₃ glass/alumina casting slurry of low temperature co-fired ceramic (LTCC) were investigated. The rheological properties, thixotropy, solid content and sedimentation properties of the casting slurry were further studied. The dispersion mechanism of four dispersants was researched and explained by infrared spectroscopy. The results show that when the amount of dispersant TEGO-700 is 2% of the powder mass, the casting slurry has the minimum viscosity (1 650 mPa·s) and the best thixotropic recovery. Under the optimum viscosity of 2 000 mPa·s for tape casting, the slurry has the maximum solid content (37.2%) and excellent sedimentation performance. The surface of the green tapes is flat and uniform in thickness, and the surface roughness is 144 nm. The surface of the sintered substrate has no obvious defects such as pores and cracks. The sintering densification is improved and the surface roughness is 210 nm. The dielectric constant and dielectric loss of sintered substrate measured at 40 GHz are 6.257 and 1.431×10^-3, respectively.

Effects of Bi₂O₃/B₂O₃ Ratio and β-Eucryptite Powder on Structure and Properties of MEMS Sealing Glass

WANG Weiwei, LI Jinwei, CAO Xin, YANG Xiaofei, ZHONG Zhaojin, NI Jia

2022, 41(11):  3990-3996. 

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A kind of lead-free glass powders based on Bi₂O₃-B₂O₃-ZnO-BaO-CuO system was prepared in this paper for the performance requirements of micro-electromechanical system (MEMS) sealing glass. The effects of Bi₂O₃/B₂O₃ ratio (n(Bi₂O₃)/n(B₂O₃)) and β-eucryptite powder content on the network structure, thermal properties, sealing temperature and sintered micromorphology of MEMS sealing glass were separately studied by Raman spectra, XRD, coefficient of thermal expansion (CTE), sintering image and SEM. The results show that the content of [BiO₃] and [BiO₆] increases with the increase of n(Bi₂O₃)/n(B₂O₃), while the transition from [BO₄] tetrahedron to [BO₃] triangulation leads to the glass network connection strength weak and structure loose. With the increase of n(Bi₂O₃)/n(B₂O₃), the CTE of the glass increases while the characteristic temperature and sealing temperature decrease gradually, but later change slowed. The CTE of the composite glass decreases obviously while the characteristic temperature and sealing temperature change little with the increase of β-eucryptite powder content, at the same time the fluidity of the composite glass powder becomes worse.

Effect of Al₂O₃ Content on Crystallization Behavior and Sintering Performance of PbO-CaO-B₂O₃-SiO₂ Glass

HAI Yun, XU Bo, YIN Xianyin, ZHU Baojing, HAN Bin, ZU Chengkui

2022, 41(11):  3997-4002. 

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PbO-CaO-B₂O₃-SiO₂ glass powder is the main component of low temperature co-fired ceramics (LTCC) raw green tape with high overload resistance. The crystallization behavior of glass powder affects the sintering performance, and then determines the performance of substrate. The effect of Al₂O₃ content on crystallization behavior and sintering performance of PbO-CaO-B₂O₃-SiO₂ glass was studied. The results show that the addition of Al₂O₃ into PbO-CaO-B₂O₃-SiO₂ glass can reduce the trend of crystallization, prevent the precipitation of high expansion crystalline phase and improve the sintering density of glass. The crystallization peak temperature of PbO-CaO-B₂O₃-SiO₂ glass powder without Al₂O₃ is 862 ℃, and cristobalite phase precipitates during sintering, which makes the average coefficient of linear expansion reach 260.8×10^-7 ℃^-1 at 20~200 ℃. The addition of 2.1% (mass fraction) Al₂O₃ into PbO-CaO-B₂O₃-SiO₂ glass can significantly reduce the crystallization capability of glass, and the expansion coefficient decreases to 72.9×10^-7 ℃^-1 after sintering at 700 ℃, with significantly increased dielectric constant from 6.30 to 7.02.

Research Progress of Compatibility Technology of Radar Shielding Stealth and Optical Transparency

SHI Xiaofei, HOU Huanran, JIN Yangli, HUANG Youqi, WANG Yanhang, ZU Chengkui

2022, 41(11):  4003-4020. 

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Radar detection and anti-electromagnetic interference are urgently needed in military and social life. The shielding stealth and optical transparency compatibility technology based on transparent applications has become one of the key research directions of this demand. In this paper, the research status of transparent electromagnetic wave shielding stealth technology in recent years was reviewed. The structures of indium tin oxide (ITO) and its composites, metal grids, metamaterials, water-based materials and other new transparent absorbing materials were introduced. Their advantages and disadvantages were analyzed, and the future development of these materials in transparent shielding stealth fields was also discussed.

Research and Development Progress of Electromagnetic Shielding Glass

GUO Chen, YANG Liqing, WAN Rui, GUAN Yongmao, CHEN Chao, WANG Pengfei

2022, 41(11):  4021-4035. 

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With the rapid development of modern technology, the electromagnetic pollution and electromagnetic interference caused and confronted by various types of communication equipments and electronic instruments are becoming increasingly complicated, so the research of electromagnetic shielding materials has been widely concerned. In the military, aerospace, medical, precision instruments, and many other fields, there is common needs to realize both optical transparency and electromagnetic shielding function at the same time, so it is of great significance to develop electromagnetic shielding glass with high light transmittance and high electromagnetic shielding efficiency. In this paper, the latest research development of electromagnetic shielding glass at home and abroad in recent years was reviewed. From the point of view of structure, electromagnetic shielding glass is divided into three types: membrane structure, grid structure and composite structure. The advantages and disadvantages of various structures and materials were summarized and analyzed, and finally the future research direction and development prospects in this field were prospected.

Research Progress on Glass Resistance to Uniform Load

YANG Penghui, WANG Yanhang, LI Xianzi, HAN Tao, LI Jiaman, ZHU Zhiguo, ZU Chengkui

2022, 41(11):  4036-4048. 

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As a typical type of brittle material, glass has draw much attention on its mechanical properties when it is used in areas of building curtain wall, windshield and side window of airplane/high-speed rail/bus, pressure window, ram engine cover, etc. At present, the research on glass resistance to uniform load mainly involves: (1) Exploring the methods to characterize the glass resistance to uniform load, such as deflection, strain rate, tensile stress and static pressure strength, etc. However, unified evaluation method has not been established yet. (2) Using calculation software, such as Ansys, to simulate glass resistance to uniform load, which can not only provide performance evaluation basis for glass component design, but also avoid destructive test. Based on the two research hotspots above, the research progress on glass resistance to uniform load was summarized, and its development trend was prospected.

Interaction Process and Reaction Mechanisms Between Glass and Water

WEI Ziya, GU Shaoxuan, WANG Xiaowei, DENG Lu, TAO Haizheng

2022, 41(11):  4049-4055. 

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Glass is often used in solution or moist environment, water erosion will affect the physical and chemical properties of glass, and even lead to glass failure. In recent years, great progress has been made in understanding the interaction process and molecular scale reaction mechanism of simple glass systems with water by using multi-scale computer simulation. This paper focuses on three simple models glass systems: quartz glass, sodium silicate glass and sodium borosilicate glass. On the basis of elucidating the origin of its water resistance, the latest progress in the interaction process and mechanism between glass and water molecules were summarized. It has important reference value for further understanding water resistance of complex system glass and developing new functional glass.

Research Progress of Stress Detection Methods for Glass-Metal Sealed Electrical Penetration Assembly in Nuclear Power System

XIANG Heng, ZHENG Ruipeng, LI Jingwei

2022, 41(11):  4056-4066. 

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Electrical penetration assembly (EPA) is a specially electrical equipment in nuclear reactors. Glass-metal sealed EPA is used in the fourth-generation nuclear reactors because of its excellent sealing performance, high temperature resistance and long service life. The sealing performance of EPA is closely related to the magnitude of stress in glass. Sufficient stress is the key factor to achieve effective sealing in harsh environment. The valid analytical measurement of stress has always been the main topic. In this review, the structure of EPA was introduced. And the influence of stress on glass-metal sealing was explained. The magnitude of stress determines the pressure resistance ability of glass-metal interface and affects the service life of EPA. In addition, the research progresses of various measurement methods of stress in glass-metal sealing including indentation technology, fiber Bragg grating technology and photoluminescence spectroscopy technique were elaborated. Moreover, the application of the finite element simulation method in characterizing stress was reviewed. Finally, the possible future research direction was proposed.

Structural Origin Revealing of Abnormal Evolution of Crack Initiation Resistance in ZnO·Al₂O₃·nSiO₂ Glasses

XU Meizi, WANG Bingbing, GU Shaoxuan, HUANG Xin, TAO Haizheng

2022, 41(11):  4067-4074. 

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To explore the evolution law of crack initiation resistance (C_R) in ZnO·Al₂O₃·nSiO₂ (n=2, 2.35, 2.5, 2.65, 3, 3.5) glasses varies with SiO₂ content, series of glass samples were prepared by the conventional melt-quenching method. By characterizing C_R and the microstructure of these aluminosilicate glasses in detail, the results shows that an abnormal evolution that C_R increases first and then decreases with the increase of SiO₂ content, and arrives the maximum value of 31.1 N at n=2.5. With the increase of n: (1) the atomic packing density decreases gradually, which induces the increase in C_R due to the increase in volume available for densification; (2) the quantity of Al—O polyhedra decreases, which leads to the drop in C_R due to the higher damage resistance of Al—O polyhedra compared to the SiO₄ units; (3) considering the strong retarding upon crack initiation originated from phase interfaces, the non-monotonic change in the quantity of phase interfaces induces the corresponding abnormal evolution in C_R for the aluminosilicate glasses. The competition and synergy of the above three factors are the structural origin of the abnormal evolution of C_R in this system. Finally, considering the insignificant change in composition near the maximum value, the non-monotonic change in the quantity of phase interfaces varies with n should be the main structual origin of the abnormal evolution in C_R.

Phase and Structure Transitions of High-Level Liquid Waste Calcine and Glass at Elevated Temperature

FANG Guang, XU Dongqing, TAN Shengheng, ZHANG Hua, JIA Ruidong, XU Kai

2022, 41(11):  4075-4080. 

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The vitrification of high-level liquid waste (HLLW) is one of the challenges in the reprocessing of spent nuclear fuel in China. The feed-to-glass conversion comprising quite complex chemical reactions and structure transitions has been of great concern. In this paper, the phase and structure transitions of the heat-treated feed (mixture of simulated HLLW calcine and glass frit) during vitrification were analyzed with DSC, in-situ XRD, NMR and Raman. The results show that the simulated HLLW calcine begins to dissolve in the glass frit at ~700 ℃, and the intermediate phases of aluminosilicates appeare at 800~900 ℃. During the reactions of HLLW calcine and glass frit at elevated temperatures, most of network modifiers from HLLW enter into the glass network of glass frit, resulting in a decrease of the network polymerization.

Effect of Alkaline Earth Metal Oxide Content on Crystallization Behavior of Simulated High Level Liquid Waste Glass

MENG Baojian, ZHU Yongchang, YANG Debo, CUI Zhu, JIAO Yunjie, LIU Hao, DAI Changyou

2022, 41(11):  4081-4088. 

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Borosilicate glass was treated as basic glass substrate, and the influence of alkaline earth metal oxide content on the crystallization behavior of waste glass containing 16% (mass fraction) simulated high level liquid wastes was investigated, in order to suppress the crystallization tendency by controlling the content of alkaline earth metal oxide under the premise of ensuring the performance requirements. The results show that,when the content of alkaline earth metal oxide is 7%~19% (mass fraction), the maximum crystallization temperature and the crystallinity of the waste glass gradually decrease with the decrease of alkaline earth metal oxide (CaO+MgO+BaO) content. The increase of the degree of polymerization of the glass network is beneficial to improving the anti-crystallization performance of the waste glass. However, when the alkaline earth metal oxide content is lower than 11% (mass fraction), the solubility of sulfate has a significant decrease. Based on the requirement of inclusion of 0.7% (mass fraction) SO₃, the appropriate composition of alkaline earth metal oxide content is above 11% (mass fraction).

Effect of Ethylene Glycol on Structure and Properties of Potassium Silicate Gel

XU Lei, ZU Chengkui, ZHANG Fan, CHEN Wei

2022, 41(11):  4089-4094. 

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In order to improve the cold resistance and maintain the stability of potassium silicate gel, the influence of ethylene glycol content on the structure, optical properties, stability and cold resistance of potassium silicate gel was investigated by infrared spectroscopy, laser light scattering, rheological test and cold resistance test, etc. The results show that with the increase of ethylene glycol content, the content of Q^3' in the network structure ofpotassium silicate gel increases gradually, and the polymerization degree increases continuously, which improves the stability of potassium silicate gel and offsets the decrease in stability caused by the decrease in solid phase content. When the ethylene glycol content reaches 11.39% (mass fraction), SiO₂ particles begin to precipitate and the Q¹ content in the network structure of potassium silicate gel increases gradually, resulting in a decrease in the transmittance from above 91% to 88.9%. The deformation rate of potassium silicate gel without ethylene glycol is 0.022 mm/h at room temperature, which decreases slightly with the increase of ethylene glycol content. When the ambient temperature increases to 60 ℃, the deformation rate is 25~27 times comparing to that of room temperature. When the ethylene glycol content is 7.89% (mass fraction), the potassium silicate gel can be kept at -12 ℃ for 6 h without freezing. In summary, under the condition of ensuring the stability and transmittance of potassium silicate gel, the cold resistance can be as low as -12 ℃.

Comparative Analysis of Mechanical Energy Loss in Different Types of Silica Glass

ZHANG Xiaoqiang, SUN Yuancheng, JIA Yonglei, PAN Yao, DU Xiurong, SONG Xuefu, ZU Chengkui, ZHU Yongchang

2022, 41(11):  4095-4102. 

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Compared with most solid materials such as metal, crystal and ceramics, silica glass has lower mechanical energy loss and it is the preferred material for many precision measuring devices. In this paper, the mechanical energy loss of four types of silica glass (Ⅰ, Ⅱ, Ⅲ and Ⅳ) were tested and compared. The influence factors and mechanism of intrinsic loss of silica glass were analyzed from material chemical composition and structural defects. The results show that the intrinsic losses of type Ⅰ and type Ⅱ silica glass are significantly higher than that of type Ⅲ and type Ⅳ silica glass. The main reasons are the high content of metal impurities and low bubble grade. Hydroxyl content is not the main factor that has significant impact on the intrinsic loss of silica glass. Surface loss is one of the main sources of mechanical energy loss of silica glass devices, and wet etching is an effective method to eliminate the surface loss.