Table of Content

15 December 2009, Volume 28 Issue 6

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Influence of the Boric Acid on Sintering and Crystallization Behavior of the Fused Silica

WANG Jin-bo;LI Kai;HUANG Shi-jun;XIAO Jian-zhong;XIA Feng

2009, 28(6):  1107-1111. 

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This article has studied the influence of the boric acid on sintering and crystallization of the fused silica. The microstructure of the sintered fused silica was studied by XRD, SEM. The results showed that the sinter ability of the fused silica could be improved by the addition of boric acid. When the boric acid content is smaller than 0.5wt%,with the boric acid content's increase, the effect is obvious; When the boric acid content is between 0.5wt% and 1.0wt%, the sinterability of the fused silica changes little; When the boric acid content is greater than 1.0wt%, the effect is much more obvious. It was also found that adding boric acid promoted the crystallization of fused silica. As the boric acid content's increasing, the crystallization is more serious, and its crystalline grows at an exponential rate. When the boric acid content is not more than 1.0wt%, the crystalline phase is all the low-temperature cristobalite phase; when boric acid was higher than 1.0wt%, the crystalline phase is mainly low cristobalite, but it also contains a little other new phase" (BSi)O_2" and "Si_(30.72)B_(1.280O_(64)".

Experimental Research on the Piezoresistive Properties of Cement-based Composites with Different Conductive Admixtures

HUANG Li;GONG Xue-jin;SUN Ming-qing

2009, 28(6):  1112-1117. 

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Conductive cement-based composites with nano-graphite, carbon black have good conductivity and piezoresistive properties, and it can use to achieve traffic monitoring. In this paper, the piezoresistive properties of high conductivity cuboid cement-based composites with any two-phase composed of graphite, carbon black, carbon fiber, under the standard vehicle force with different load cycle are studied. For the selected cases, experimental results show that cement-based composite mixed with graphite and carbon fiber under a certain ratio and vehicle force has the best piezoresistive properties, and compound conductive phase mixed with graphite and carbon black is better than that mixed with carbon black and carbon fiber.

Properties Research on Discharge Cutting of P-type Mono-crystalline Solar Silicon

BI Yong;LIU Zhi-dong;QIU Ming-bo;WANG Wei;TIAN Zong-jun;HUANG Yin-hui

2009, 28(6):  1118-1122. 

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Researched the special electrical characteristics of P-type mono-crystalline solar silicon under conduction mode and polarity selection through the volt-ampere property test of it which detected the conduction current of it under D.C. pulse voltage, and the circuit model with diode and resistance was created. The test discovered that P-type mono-crystalline silicon had unidirection continuity. Subsequently, P-type mono-crystalline solar silicon with resistivity of 2.1 Ω·cm was cutting and single pulse voltage and current wave was grabbed respectively, which further researched the special discharge cutting properties of P-type mono-crystalline silicon with extremely complicated electrical characteristics in the actual cutting, and found that current wave of P-type mono-crystalline silicon showed "ramped" and silicon wafer after cutting morphology showed "conchoidal". The results show that the interelectrode resistance of P-type mono-crystalline silicon will decrease as the available area of the electricity interface growing, but the current of cutting will increase, and positive polarity machining is suitable for discharge cutting P-type mono-crystalline silicon.

Effect of Preparation Method on the Structure and Performance of TiO_2/HZSM-5 Photocatalyst

WU Yan-lin;HU Yun;WEI Chao-hai

2009, 28(6):  1123-1128. 

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TiO_2/HZSM-5 photocatalysts were prepared by impregnation, Sol-gel and solid state dispersion methods, using ammonium titanyl oxalate, tetrabutyl titanate and P-25 as titanium source respectively. The photocatalytic reactivity of the prepared samples for the degradation of methyl orange(MO) under UV light irradiation were investigated. The catalyst prepared by a simple, easy to control and organic-solvent-free impregnation method showed a higher photocatalytic activity than that prepared by Sol-gel and solid state dispersion methods. The structure of the catalysts were characterized by XRD,UV-Vis DRS and BET technologies. It was found that TiO_2/HZSM-5 prepared by impregnation had a higher surface area and the nano TiO_2 particles well dispersed on the surface of zeolite leading to a higher photocatalytic activity.

Study on Phase Composition and Microstructure of Al_2O_3-Si Material during Heating under Carbon Embedded Condition

LIU Xin-hong;YE Fang-bao;XIE Juan-juan;ZHONG Xiang-chong

2009, 28(6):  1129-1133. 

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The Al_2O_3-Si material has been prepared by using fused corundum aggregates and fines, 5%-8% Si powder as starting materials and sulfite lye as binder. Changes in phase composition and microstructure of Al_2O_3-Si material during heating at 1000-1600 ℃ under carbon embedded condition have been studied. The results show that after firing at 1200 ℃, Si begins to react with CO to form SiC whiskers which are interlocked with each other within the pores of the materials. After firing at 1300-1400 ℃, SiC whiskers are found to increase noticeably in amount together with growth in crystal size. The SiC whiskers are observed to be interspersed within the corundum skeleton structure mostly in the form of continuous interlocking network. Minor amount of O'-SiAlON crystals are observed at 1400 ℃. After firing at 1500-1600 ℃, SiC continues to grow in crystal size, most of them exhibit bending and arborization tendency. The residual Si is melt exhibiting plastic deformation and takes as sintering aid.

Influence of Additives on Vitrified Bond Melting Temperature of CBN High-speed Grinding Tool

SONG Peng-tao;XUE Qun-hu;CHEN Yan-wei

2009, 28(6):  1134-1138. 

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MgO,P_2O_5,CaCO_3 and ZnO on melting temperature of CBN vitrified bond with SiO_2,Al_2O_3 + B_2O_3 as glass-forming agent, and the wettability of vitrified bond added four additives to CBN particles at high-temperature was studied. The three sets of samples were fused、water quenched to study the melting temperature of the sample before and after shrend,and the phase composition was determined after water quenched. The results showed:the influence of four additives on vitrified bond melting temperature was P_2O_5＞MgO＞＞ZnO ＞＞CaCO_3;the sample after water quenched had better uniform chemical composition,lower melting temperature,and the melting sample existed in the form of glassy phase.

Antipermeation and Attenuation Mechanism of Bentonite, Zeolite and Red Mud Liner for Garbage Landfill

CHEN Lei;LIAO Li-bing;ZHANG Xiu-li

2009, 28(6):  1139-1142. 

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Column tests of bentonite, zeolite and red mud liners were conducted. Based on the analysis and comparison of the phase components of bentonite, zeolite and red mud liners and the composition of the leachate pre and post permeation, the antipermeation and attenuation mechanism of bentonite, zeolite and red mud liners for garbage landfill was discussed, which providing reference for the construction of multilayer liners of bentonite, zeolite and red mud. The results indcated that the permeability and attenuation capability of bentonite depent on its water absorption and adsorbability. Complicated channel structure of zeolite made it have good ability of attenuation. Calcite and aragonite in red mud increased after permeation, and the strength increase, which ensured the integrity of liner. Attenuation also enhanced after Fe~(3+) reduced by organic compounds.

Preparation of Magnesia-hercynite Refractories

ZHANG Jun-bo;XIAO Guo-qing;LIU Xing-ping;FAN Yong-lian;LIU Bin;ZHANG Zheng-fu

2009, 28(6):  1143-1148. 

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The magnesia-hercynite refractories were prepared with magnesia and hercynite by sintering process. The bulk density, apparent porosity and cold crushing strength were measured. The elastic modulus of samples was measured by the method of stress and strain. The phase constituents of specimens was analyzed by X-ray diffraction (XRD), and the microstructure was observed with scanning electron microscopy (SEM).The experimental results show that the appropriate sintering temperature for samples is 1600 ℃ with the highest bulk density and the lowest apparent porosity . The cold crushing strength of samples decreases with the adding of the content of hercynite. The optimum content of hercynite is 3%-4%. The specimens with addition of hercynite particles have higher elastic modulus, so the specimens with addition of hercynite particles have better thermal shock resistance than the specimens with hercynite powder. Thermodynamic calculation show that: the magnesia reacts with hercynite resulting in magnesia-alumina spinel at temperature higher than 182 ℃. The microstructure photos also show that iron protoxide in hercynite can diffuse into magnesia particle and reacts with magnesium oxide, and forms magnesia-alumina spinel ring around magnesia when magnesia-hercynite refractories are sintered at high temperature. The reaction leads to produce microcrack between hercynite and magnesia particle.

Effects of Fe-Si_3N_4 Addition on the Mechanical Properties of MgO-based Castables

TU Jun-bo;WEI Jun-cong;CUI Bo

2009, 28(6):  1149-1153. 

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The effects of Fe-Si_3N_4 addition on the room temperature physical properties and hot mechanical properties of MgO-based castables using magenisite as main raw and micropowder as binder were investigated. The phase and microstructure were analysed by XRD, SEM. The results show that as the increase of Fe-Si_3N_4 addition the drying strength decreases .The immediate temperature strength increases first and then decreases and the maximum value is obtained when 3% Fe-Si_3N_4 is added. High temperature strength increases first and then drops.The hot modulus of rupture maximizes when 3% Fe-Si_3N_4 is added. Fe-Si_3N_4 partially oxidizes to produce SiO_2 and further tranforms to fibrous M_2S contributing to strength.The phase containing iron can produce solid solution with magnesia contributing to sintering .

Fabrication of ZrO_2/Stainless Steel Gradient Pipes by Tape Casting on Curved Surface

LI Jun;ZHAO Kang;TANG Yu-fei;LI Da-yu

2009, 28(6):  1154-1157. 

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ZrO_2 pipe and SUS316L pipe were fabricated by multi-tape casting on the curved surface of a cylinder using ZrO_2 and SUS316L slurries. Influence of the viscosity of the slurry on thickness uniformity of green sheets was investigated. And then six kinds of slurries were cast on the curved surface in the order that the ZrO_2 content was reduced sequentially. ZrO_2/ SUS316L graded pipe with regular shape was successfully obtained by inducing the residual stress as a result of optimizing shrinkage. The experiment results show that the thickness error was less than ±5% when the viscosities of slurries are range from 1200 to 2000 mPa·s. In order to reduce the residual stress, the binder content should be increased with increasing ZrO_2 content so that the difference of shrinkages is decreased.

Research on Preparation of Sulphoaluminate Cement Clinker by Desulphogypsum

CHEN Wen-juan;LI Hai-tao;CAI Xu-heng;SHENG Yan-hong;CHANG Ai-xin

2009, 28(6):  1158-1162. 

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An experimental research on the preparation of sulphoaluminate cement clinker with desulphogypsum instead of natural gypsum has been performed.The results show that the burden ratio of raw materials is m(bauxite)∶ m(limestone)∶ m(desulphogypsum)=35∶ 43∶ 22, the best calcination temperature was determined of 1400 ℃. Under the process conditions, qualified sulphoaluminate cement clinker can be produced and main mineral composition of cement clinker are calcium sulphoaluminate and dicalcium silicate. Effects of calcination temperature on clinkering process was explored by observing appearance characteristics and by the means of XRD and SEM. At 1300 ℃,the clinker is underburnt with loose structure, lower strength and the main crystal phase of C_4A_3 ,β-C_2S and 2C_2~-S·CaSO_4; at 1400 ℃, it is normal and qualified clinker with tight structure, higher strength and the main crystal phase of C_4A_3 ,β-C_2~-S and C_4AF; at 1500 ℃, it is overburnt clinker with excessive liquid, harder bulk and the main crystal phase of C_4A_3 , β-C_2~-S, C_12A_7and CT.

Effects of BaCu(B_2O_5) Additive on Low Temperature Sintering and Dielectric Properties of CaO-BaO-Li_2O-Sm_2O_3-TiO_2 Microwave Dielectric Ceramics

SUN Lu;HUANG Jin-liang;GU Yong-jun;LI Qian

2009, 28(6):  1163-1166. 

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Effects of BaCu(B_2O_5) on the dielectric properties of 14CaO-4BaO-8Li_2O-12Sm_2O_3-63TiO_2 microwave dielectric ceramics were investigated. The crystalline structure and micromorphology were studied by XRD and SEM, respectively. The sintering temperature of the specimens could be reduced from 1325 ℃ to 1100 ℃ and perovskite phase and BST phase were formed after sintering at 1100 ℃ for 2 h. The specimens with 6wt% BaCu(B_2O_5) sintered at 1100 ℃ for 2 h showed Kr of 87.76,tanδ of 0.018,TCF of -4.27 ppm/℃ (1 MHz).

Research on the Rheological Behaviors of Si-based Slurries

JI Li-juan;BAI Pei-kang;REN Wei;PU Yu-ping;YIN Hua

2009, 28(6):  1167-1172. 

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Three kinds of Si-based slurries:(1)100wt%Si(2)5wt%Si_3N_4,95wt%Si(3)5wt% Si_3N_4,10wt%SiC,85wt% Si were synthesized.The rheological behaviors of Si-based slurries were investigated by changing additions of(C_2H_5O)_3PO and pH value.The results showed that the isoelectric point (IEP) of Si is around pH value of 3.1.The rheological behaviors of the slurries with different additions of(C_2H_5O)_3PO and at different pH could be significantly improved;the best content of (C_2H_5O)_3PO and the best pH were known respectively.

Study on Preparation of Concrete Expanding Admixture by Hard Clay and Ardealite

ZHOU Shuang-xi

2009, 28(6):  1173-1176. 

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Calcining way is used to activated hard clay. The anhydrite was obtained by calcined and dehydration ardealite. The efficient expanding admixture of concrete is the btained by mixing anhydrite and calcining hard clay. The result indicate that expansive admixture meet requirement specified in industry standard JC476-2001. From SEM picture of 90 d cement pastes with expanding admixture, it can be seen that the formation of AFt and C-S-H with significant SO_3, Al_2O_3 and its adsorbing water are responsible for the expansion of expansive mortar of concrete.

Processing and Performance of Hydroxyapatite/Hydroxyfluorapatite Double Layer Coating on Alumina

ZHU Qing-xia;TAN Shun-yan;XU Qiong-qiong

2009, 28(6):  1177-1181. 

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A hydroxyapatite/hydroxyfluorapatite (HA/FHA) double layer was coated on Al_2O_3 by a powder slurry method. Each layer(HA,FHA) was deposited on Al_2O_3 repeatedly to induce a uniform layer and the final heat treatment was carried out above 1300 ℃ to consolidate the coating layer. During this process, without the FHA-intermediate layer, a severe reaction between HA and Al_2O_3 occurred to form tri-calcium phosphate and calcium aluminates. SEM, XRD and bonding tests of the coatings were performed. The results showed that the FHA layer between the HA layer and the Al_2O_3 substrate was effective in suppressing the reaction between HA and Al_2O_3.The obtained HA/FHA double coating was micro-porous and relatively rough, but was firmly adhered to the Al_2O_3 substrate, having a bonding strength of approximately 30 MPa after heat treatment above 1300 ℃.

Preparation of Ce-Fe Co-doped TiO_2 Nanopaticles and Their Photocatalytic Performance under Energy Saving Lamp

LI Gui-hua;WANG An-feng;YUAN Bian-qin;REN Qiao-qiao

2009, 28(6):  1182-1185. 

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Ce-Fe co-doped TiO_2 nanopaticles were prepared via Sol-gel process and their decolorization performance of methylene blue under energy saving lamp were investigated. The effects of catalyst composition,catalyst concentration and reaction temperature on their photocatalytic performance were studied. The results indicated that Ce-Fe co-doped TiO_2 showed markedly higher photocatalytic activity than that of TiO_2 and Ce or Fe single doped TiO_2. TiO_2 co-doped with 0.0625% Ce and 0.004% Fe showed the highest photocatalytic efficiency. And using this catalyst when the catalyst concentration was 0.313 g/L,the reaction temperature was 50 ℃ and pH was 5.33 the degradation rate in 4 h could reached 96.00%. XRD characterizing indicated that emulsion of anatase and rutile had better photocatalytic activity and their diameters were between 20 to 30 nm.

Automatic Allocation of Correlation Peaks of Large Capacity Volume Holographic Correlation Recognition Systems

MENG Fan-wei;ZHAO Ye-quan;ZHANG Xue-feng;YANG Yong-gang

2009, 28(6):  1186-1190. 

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To increase the quality of correlation peaks, near stoichiometric Mg:Fe:LiNbO_3 crystals is used as memory and correlator due to its better uniformity and optical quality. A correlation peaks allocation algorithm based on neighborhood variance increment is presented, which is on the foundation of neighborhood entropy. This algorithm not only can distinguish target from edge texture, but also is not influenced by background intensity. With 1000 holograms stored, it takes less than 3 s to allocate correlation peaks accurately against correlation output image with 1024×768 pixels, and a satisfied recognition result is also achieved.

Porosimetry Techniques and Their Applications in Pore Structure Characterization of Hardened Cement Pastes

SHEN Ye-qing;DENG Min;MO Li-wu

2009, 28(6):  1191-1196. 

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This paper summarizes the recent progress of traditional MIP, method of synchrotron X-ray microCT (SX-microCT) and technique of NMR relaxation time, NMR cryoporometry on pore structure characterization in hardened cement pastes. First-hand information of pore structure, when calculating pore structure distribution from traditional MIP method, can be available directly without so many complex models or assumptions. Utilizing the advantage and combining with new reported porosimetry technology expect to realize new breakthrough of pore structure characterization in hardened cement paste. SX-microCT and NMR relaxation time could be better ways to characterize meso-pore structure within hardened cement paste, while NMR cryoporometry could characterize micro-pore structure. Whether NMR relaxation time or NMR cryoporometry, ferromagnetic materials existence in cement paste maybe have effect on NMR measurement precision. It needs further research in the future.

Progress and Application of Carbon Fibers Reinforced Silicon Carbide Ceramic Matrix Composites

HE Bo-lin;SUN Jia

2009, 28(6):  1197-1202. 

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Carbon fibers reinforced silicon carbide ceramic matrix composites have received intensive interest due to their excellent properties such as low density, high strength and toughness, oxidation resistances. The development of carbon fibers was reviewed. The several preparation methods of C_f/SiC composites were introduced. The advantage and disadvantaged of every method were analyzed. The application of C_f/SiC composites were described as the outstanding high temperature structure materials and braking materials. Finally, problems for further research and key study aspects in the future were pointed out.

Research Progress in Machinable Fluormica Glass-ceramics

ZHANG Wei-yi;GAO Hong

2009, 28(6):  1203-1207. 

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Machinable fluormica glass-ceramics are a new type of structural materials. The materials have been a focal point in the field of ceramic researches since being developed because these materials can be machined by conventional metallic tools. The major crystalline phases in the traditional fluormica glass-ceramics are fluorphlogopite and tetrasilicic fluormica. In this paper, the recent advances at home and abroad in the researches of barium-mica, calcium-mica, lithium-mica glass-ceramics and multiple phase fluormica glass-ceramics are reviewed.

Research Progress on Rare Earth Colored and UV Absorption in Glass

ZHANG Xiao-wei;LI Mei;LIU Zhao-gang;HU Yan-hong;WU Jin-xiu

2009, 28(6):  1208-1212. 

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Researches and applications of rare earth in glass coloring and UV absorption at home and abroad were introduced in this paper.Combination rare earth and transition metal element was used to show better coloring for glass. Mixture of cerium and iron, titanium and other metal was used to develop various anti-UV glasses.

Advances in the Preparation of Pillared Silicate Materials by Intercalation Methods

DU Xu-jie;LI Guo-chang

2009, 28(6):  1213-1219. 

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In this paper,recent advances in preparation pillared materials from layered silicates by intercalation methods and its thermodynamics process were summarized.The important applications of pillared silicates and its further develops in future were introduced in the last.

Research and Development of the Vanadate Photocatalysts

LIU Ye;DAI Chang-hong;MA Jun-feng;SONG Zu-wei;SUN Yong;FANG Jing-rui;ZHAO Jin-gang;SUN Xia;GAO Chang;LIU Zhen-sen

2009, 28(6):  1220-1224. 

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Metal vanadates were mainly used as photoluminescence materials, laser materials, cathode materials for rechargeable lithium batteries, recently. As a new photocatalystthey, they have attracted much attention. In this paper, the synthesis and modification of the vanadate photocatalysts including BiVO_4,InVO_4,Ag_3VO_4 and FeVO_4 were briefly reviewed. Meanwhile, the photocatalytic activity of photocatalyst under different conditions were analyzed and discussed. In addition, the problems which need to be solved were proposed.

Analysis of Carbonation on Portland Cement Concrete

HE Juan;YANG Chang-hui

2009, 28(6):  1225-1229. 

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Carbonation reaction and carbonation process of portland cement concrete were introduced,and carbonation of Ca(OH)_2 and calcium silicate hydrated(C-S-H)was analyzed. The analysis showed: C-S-H also reacted with CO_2 while Ca(OH)_2 reacted with CO_2. The main carbonated product of Ca(OH)_2 was calcite and that of C-S-H was amorphous silica gel, and maybe unstable, poorly crystallized aragonite and vaterite were formed. Decomposition temperature of aragonite and vaterite was lower than calcite. C-S-H with low C/S and poor crystallinity was prone to carbonation; the rate of carbonation became higher with higher alkali content.

Growth of Near Stoichiometric Mg∶ Fe∶ LiNbO_3 Crystals and Their Optical Performance

MENG Fan-wei;ZHAO Ye-quan;ZHANG Xue-feng

2009, 28(6):  1230-1234. 

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Near stoichiometric Mg∶ Fe∶ LiNbO_3 crystals were grown by top-seeded solution growth method with K_2O as fluxing medium. UV-Vis spectra, IR spectra, photodamage resistance ability and diffraction efficiency are measured. The results show that with the increase of doped Mg, the absorption edge of crystals shift to the violet firstly, and then shift to infrared. The photodamage resistance ability increases, but the diffraction efficiency decreases. The OH- absorption peak is bimodal distribution. Location model of doped Mg, Fe ions are given. [Li]/[Nb] ratio in crystals, attributed indirectly, is about 49.7-49.8%, the threshold concentration of Mg in doped near stoichiometric LiNbO_3 crystals is between 2% and 3%.

Synthesis of Several Modified Triethanolamine Compounds and Their Effects on Portland Cement Grinding

WANG Bin;ZHENG Qiang;WANG Sheng-ping;CHEN Xin-sheng;BAI Ming-ke;WANG Ming-gang

2009, 28(6):  1235-1240. 

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The aim of the present paper was the evaluation of five additives from modified triethanolamine, which were synthesized at a laboratory stage used for Portland cement. To get a valuable result, a reference sample was made with triethanolamine. These compounds were carried out by interground with gypsum and clinker in closed-circuit grinding systems for different concentration and grinding duration. The investigation were performed using the specific surface of the solid, size distribution,D_(50) ,uniformity factor "n" and strength. Then, the action mechanisms were discussed. The result showed that at low concentration additives from modified triethanolamine class had substantial grinding advantage in comminution vs. triethanolamine, and the effect of triethanolamine maleate on cement grindability and strength development is the best.

Properties of CaO-B_2O_3-SiO_2 Glass Ceramics Doped with Li_2O

NING Ge;LIU Min;ZHOU Hong-qing;ZHU Hai-kui;XU Gui-jun

2009, 28(6):  1241-1244. 

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The effects of 1.0-2.5wt% Li_2O sintering aid on the properties of CaO-B_2O_3-SiO_2(CBS) glass ceramics were investigated by different analytical techniques such as DTA, XRD, SEM. The results show that Li_2O sintering aid decreases glass transition and crystallization temperatures. The sintering temperatures of CBS glass ceramics doped with Li_2O decrease significantly from 930 ℃ to 820 ℃. Adding with 1.0wt% Li_2O, the sintering temperature of the sample is between 760 ℃ and 820 ℃. The dielectric constant and dielectric loss of the sample sintered at 800 ℃ are 5.71 and 0.0024 at 10 MHz, respectively.

Preparation of Silica for Rubber

ZHAO Jie;QIAN Hai-yan

2009, 28(6):  1245-1248. 

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In the reaction process of silica by oil of vitriol precipitation, oil-absorbed value, bulk density, size of amorphous silica were studied by reaction time and reaction temperature. The result shows that with the increasing of the reaction time, the oil-absorbed value increased first and decreased then, bulk density decreased first and increased then, the size of amorphous silica decreased first and increased then. With the increasing of reaction temperature, the oi-absorbed value increased first and decreased then, bulk density decreased first and increased then, the size of amorphous silica gradually decreased. Through the comprehensive analysis of factors, the best reaction temperature is 85 ℃, the best reaction time is 20 min. Silica is prepared for rubber reinforcement.

Effect of α-Al_2O_3 Micro-powder on Properties of Low Carbon MgO-C Refractories

XIE Zhao-hui;YE Fang-bao

2009, 28(6):  1249-1253. 

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Effects of α-Al_2O_3 micro-powder on properties of low carbon MgO-C refractories were investigated with fused magnesia and flake graphite as starting materials, and Novolak phenolic resin as binder. The results show that: (1) with Al_2O_3 micro-powder addition, apparent porosity of MgO-C refractories decreases, both bulk density and MOR increase, and especially oxidation resistance improves noticeably. (2) The reaction of Al_2O_3 micro-powder in the matrix of MgO-C improves the textual integrity of MgO-C refractories and ceramic bonding, due to formation of an continuous in-situ spinel matrix. (3) The inward diffusion velocity of oxygen through the porous decarburized layer is slowed down by the formation of MgO dense layer and continuous in-situ spinel matrix, which results in the improvement of oxidation resistance.

Influence of Side Chain Density of Polycarboxylate Superplasticizer on Hydration of Cement

LEI Xi-ping;LI Hui

2009, 28(6):  1254-1258. 

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Polyethylene glycol monomethyl ether acrylate macromer was synthesized by esterification using polyethylene glycol monomethyl ether ((-M)n=750)and acrylic acid as monomers. Polycarboxylate superplasticizer with different side chain density (-OC_2H_4-) was synthesized by copolymerization with macromer, sodium allylsulfonate and acrylic acid at different molar ratio in the initiator of ammonium persulfate. The results shown that the fluidity, dispersivity was increased with -OC_2H_4- increased, especially at n(-COOH)∶ n(-OC_2H_4-)=1∶ 1. The water reduction ratio was over 24 % and reached maximum value 28.5% as n(-COOH)∶ n(-OC_2H_4-)=1∶ 1. The strength of cement mortar was enhanced with -OC_2H_4- increased comparing with blank cement. It can also be proved by SEM and XRD analysis.

Synthesis and Characterization of YAG∶ Ce Phosphor by Citric Acid-gel Method

SUN Hai-ying;ZHANG Xi-yan;WANG Neng-li;MI Xiao-yun;LIU Quan-sheng

2009, 28(6):  1259-1262. 

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YAG∶ Ce phosphor was synthesized by citric acid-gel method. The effects of spectrum intensity of the concentration (x) of Ce ion and calcination temperatures were studied.The result indicates that spectrum intensity of phosphor increases with the concentration (x) of Ce ion when x is less than 0.07, the spectrum intensity of phosphor decreases with the increase of x when x is more than 0.07.The crystallinity of powders and spectrum intensity of YAG∶ Ce phosphor increase with the increasing of calcination temperatures. It is also found that parameters such as temperatures and x do not affect the peak shape and peak locations, the main excitation peak locates at 469 nm and the main emission peak locates at 529 nm .

Digesting of Free-CaO in the High Calcium Fly Ash

LI Hui;SHI Shi;FENG Shao-hang;Shen Bao-jing;ZHANG Ju-qing

2009, 28(6):  1263-1266. 

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In this paper, high calcium fly ash (HCFA) from circulating fluidized bed (CFB) boiler calcined at low temperature was disposed by means of adding digesting agent, grinding and filling dispersing agent to digest the free-CaO inside it. The content of free-CaO in HCFA dealt by different means was tested, and the micro-structure and appearance of HCFA particles before and after disposal were observed by SEM. The results indicated that without filling dispersing agent, digesting of free-CaO was influenced by the amount of digesting agent mostly, then particle size of HFCA, and at last the digesting time. With the aid of dispersing agent, more water got into HCFA particles and the digesting of free-CaO was accelerated. SEM pictures revealed that abundant Ca(OH)_2 with hexagonal flakes, plates and column appearance came into being on the surface of particles after HCFA dealt with digesting agent,while fine Ca(OH)_2 crystal clusters emerged inside the particles of HCFA after this material was digested both with digesting agent and dispersing agent.

Stability of Ettringite in FBC Ash Paste

WANG Zhi-juan;SONG Yuan-ming;XU Hui-zhong

2009, 28(6):  1267-1270. 

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FBC ash contains much calcined clay minerals, sufficient free lime and anhydrite, so ettringite can be found in cemented FBC ash paste. To describe the stability of ettringite in FBC ash paste, the content change of it by the age was studied by X-ray diffraction (XRD) and chemical analysis. The results show that the content of ettringite increases with ages before 28 d cured in standard condition, but decreases subsequently. It is affirmed that the stability of ettringite in FBC ash paste is poor, and the formed earlier will decompose.

Study on the Dispersed Characters of Alumina Powders in Aqueous Suspension

TANG Bin-ghua;LUO Qing-ping;HUANG Yun

2009, 28(6):  1271-1275. 

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The dispersing characteristic of Al_2O_3 powders in suspension was investigated by Zeta potential. The influence of different dispersing conditions, such as different ultrasonic dispersing time, different granularity of Al_2O_3 powders, different dispersant concentration and different pH value of Al_2O_3 powders suspension, on the Zeta potential of Al_2O_3 powders was studied. Results indicate that the absolute value of Zeta potential of Al_2O_3 powders varied with these different dispersing conditions, and there was a best dispersing time range of 4-6 min and a best dispersant concentration of 0.5% while the Al_2O_3 powders dispersed well, and the absolute value of Zeta potential increased with the pH value in alkalescence condition.

Preparation and Study on Self-dispersal Nano Carbon Black Pigment

YANG Xin-yu;WANG Zhao-lun;PAN Ming-chu;LIANG Xiao-juan;LIU Hai-tao;XIANG Wei-dong

2009, 28(6):  1276-1281. 

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In order to obtain self-dispersal nano carbon black pigment. Carbon black surfaces were modified by nitric acid oxidation.The surfaces group structure, surfaces oxygen content of the original and oxidized carbon black were investigated by means of FT-IR, XPS, Element analysis instrument, respectively. The oxidized carbon black and distilled water were mixed according to 30% solid content, after which the mixture was ground for 45 min by small-grinding mill equipment, and self-dispersal nano carbon black pigment would be prepared successfully. The particle size distribution and the dispersal stability of the pigment were investigated by means of particle-size analyzer, spectrometer, respectively. The results showed that some highly marked hydrophilic character functional groups on carbon black surfaces, including C=O, O-C=O, O-H, were increased greatly by nitric acid oxidation and the oxygen content of oxidized carbon black was incresed nearly 6 times comparing original carbon black. The particle size distribution of self-dispersal nano carbon black pigment was within 200 nm and nano carbon black pigement was homogeneous and stable.

Study on the Characteristics of the Fly Ash from Coal Gangue-fired Power Plant

CHEN Jie;HUANG Qing-xiang

2009, 28(6):  1282-1285. 

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The physical and chemical characteristics of wet fly ash from coal gangue-fired power plant in shaanxi were studied by using chemical analysis, laser sizer, XRD, SEM and other techniques. The experimental results showed that the wet gangue fly ash has anomalous particles with 20-70 μm. The chemical composition contains mainly SiO_2,Al_2O_3 and Fe_2O_3 with more than 70% content. It has lower calcium content and higher ignition loss, meeting the national standard of Ⅲ grade of fly ash. Fly ash consists of porous amorphous phase, carbon grain and a small amount mineral crystal which dominated by quartz, mullite and hematite. In filling and supporting of coal mine, the wet fly ash can be activated by combining with physical and chemical activation and adopting special techniques further.

Effect of Cordierite on Properties of Mullite-bauxite Castable Refractory

ZHANG Wei;DAI Wen-yong;NOBUAKI Chiyoda

2009, 28(6):  1286-1290. 

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The effects of different cordierite contents on the properties of mullite-bauxite castable refractory were analyzed respectively by taking the mullite, bauxite as main raw materials and taking calcium aluminate cement as binding system. After 24 h curing in mould and another 24 h curing at 110 ℃ after demoulding, the specimens were heat treated at 1000 ℃,1300 ℃ and 1500 ℃for 3 h respectively. The permanent linear change, bulk density, modulus of rupture, clod crushing strength, thermal expansion coefficient and thermal shock resistance were examined. The results showed that bulk density of mullite-bauxite castable refractory is reduced with the increasing of cordierite content. The modulus of rupture is reduced with the increasing of cordierite content after 1000 ℃ and 1300 ℃; Thermal shock resistance of mullite-bauxite castable refractory is improved with the increasing of cordierite content, conservation rate of strength is increased gradually, and low bulk density contributes to high conservation rate of strength after thermal shocking.

Study on Effect of Cation on the Acetate Intercalated Kaolinite

ZHAO Shun-ping;WANG Tao;XU Heng;XIA Hua;GUO Yu

2009, 28(6):  1291-1294. 

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The kaolinite/sodium acetate (K/NaAc) and kaolinite/potassium acetate (K/KAc) intercalation compound were prepared by grinding method. The intercalation compound was characterized by the X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), simultaneous TG-DSC apparatus. And the effects of different cation on the intercalation results were studied. The results showed that the difference of K~+and Na~+ have a great impact on the intercalation results. Sodium acetate intercalation compound appears two diffraction peaks of 0.979 nm and 0.765 nm and formed a new bond between the kaolinite interlayer, compared with potassium acetate intercalation compound only one diffraction peak of 1.365 nm. Acetate molecules are upright in the kaolinite interlayer. And acetate cation and methyl may enter the hole in the tripartite complex.

Quantitative Analysis of Periclase in Cement Clinker

CHEN Fu-song;XU Ling-ling;ZHANG Zhi-bin

2009, 28(6):  1295-1299. 

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In this paper, quantitative analysis of magnesium oxide in cement clinker is introducted briefly, and chemical analysis method and XRD internal standard method were used to determine the content of periclase in cement clinker, and the determined accuracy was evaluated by recovery. The results show that it is feasible to determine periclase in cement clinker using these two methods .The periclase recovery of chemical method is more than 99.40% and the results of chemical method is accordance with that of XRD internal standard method.

Calculation and Verification of Adiabatic Temperature of Self-propagatingreaction System Based on the Database of Materials' Thermodynamics

JI Wen-wen;SONG Yue-peng;YANG Jun

2009, 28(6):  1300-1305. 

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The materials' thermodynamic parameters database of self-propagating reaction system is established. Based on this database, visualization computer numerical calculation system of adiabatic temperature is developed by VB program. The calculation results of more than 60 kinds of self-propagating system agree well with experimental ones. Furthermore, the effect of preheating temperature and dilution agent addition on the adiabatic temperature of self-propagating system is also discussed.

Adsorption of Hydroquinone by Anion-cation Organopalygorskite

CHANG Yue;LU Feng;LV Xue-qian;ZHA Fei;LIU Hong-wei;YAN Jun

2009, 28(6):  1306-1311. 

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Anion-cation surfactant modified palygorskite were prepared by adopting microwave assistant. The sorption property of modified palygorskite for hydroquinone in water was studied. Comparing to natural palygorskite and cation surfactant modified palygorskite, ability of adsorption of anion-cation surfactant modified palygorskite is higher in the treatment of hydroquinone. The maximum sorption capacity was 137.50 mg/g.The adsorption equilibrium is in accordance with the Langmuir isothermal adsorption equations. Thermodynamic function calculated shows that the adsorption is a spontaneous and exothermic process. Enthalpy and entropy change of the adsorption of hydroquinone are -93.582 kJ/mol and -299.32 J/(mol·K), respectively. Free energy of the adsorption increases with the increase of temperature.

Orthogonal Test Research on Spontaneous Combustion Coal Gangue's Compound Activation

ZHOU Mei;WU Ying-qiang;ZHANG Xiao-fan

2009, 28(6):  1312-1316. 

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The mechanical properties of spontaneous combustion coal gangue's bonding material was researched by physical and chemical activation method.The research is based upon checking the element property of spontaneous combustion coal gangue in Gaode Mine,Fuxin city of Liaoning Province. The physical research showed that this coal gangue has good grindability;the orthogonal test on the bonding material which take the spontaneous combustion coal gangue as the primary material analysis the influence of powdered ore,calcium oxide,dihydrate gypsum and sodium silicate's content on bonding material's strength. Chemical research showed that spontaneous combustion coal gangue can still make C42.5 cement with high content (74%) under the interaction of compound activation. According to analysis of variance results, we are able to determine the optimum mix proportion of bonding material which can provide useful technical reference to exploit geopolymer cement from spontaneous combustion coal gangue.

Study on Effect of Raw Materials on the Quality of Powder Coal Ash Aerated Concrete

YAN Han-jun;ZHANG Chan-juan

2009, 28(6):  1317-1321. 

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Coal ash aerated concrete is the promotive project of the country, but the quality of concrete is often difficult to control. This paper discusses the problems about the raw materials on coal ash aerated concrete. The law of the using of raw materials on the coal ash aerated concrete with experiment dates was found in practice study.

Effect of Surfactants on Silica Colloids Stablity

TIAN Li-peng;WANG Li

2009, 28(6):  1322-1326. 

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Effect of surfactants on viscosity and stability of silica colloids was investigated. Different surfactants were directly added and then viscosity changes and stablity were determined. It showed the viscosity reduced after anionic surfactant added, the CMC of surfacant is about 4.6×10~(-3) mol/L, the stablity increased reversly, the extremum is about 1.43×10~(-3) mol/L. It was speculated that the viscosity reduction was relied on the covering process of SDBS on the colloids particles, but stablity mainly because of formation of micelle and absorption of SDBS was disadvantageous. The stablity could be increased by addition of anionic and nonionic surfactant, but reduced by cationic surfactant.

One Step Synthesis of Gas Sensor Material Nanosized In_2O_3 by Surfactant-hydrothermal Method

LOU Xiang-dong;LI Pei;WANG Xiao-bing;QIN Nan;WANG Xue-feng

2009, 28(6):  1327-1331. 

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The preparation of In_2O_3 nano-powder used one-step hydrothermal method with PEG-600 as surfactant. Its size, phase and morphology were analyzed by XRD, SEM and TEM. The gas sensing characteristics of the materials were tested in static slate. The results show that the morphology of In_2O_3 is nanorods with good dispersity. The average length of the as-synthesized nanorods reaches about 150 nm, and the width about 20 nm, giving an aspect ratio of a few hundreds. It has a high sensitivity as high as 32.2 to 10 ppm NO_2 at lower working temperature 125 ℃. The sensor based on In_2O_3 also has satisfactory selectivity, quickly response and recover times.

Study on in Situ Polymerization of Polyacrylonitrile / layered Double Hydroxide (PAN/LDH)

JIA Zhao;TIAN Gui-shan;YANG Yan-gong

2009, 28(6):  1332-1335. 

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Using in situ polymerization, the monomer acrylonitrile (AN) was intercalated and polymerized with benzoyl peroxide (BPO) as the initiator between the layer of layered double hydroxide (LDH). The structure of Polyacrylonitrile/layered double hydroxide (PAN/LDH) was characterized by Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). Both the flame retardant property and heat resistant were investigated. The results showed that PAN has been prepared between the layer of LDH by in situ polymerization and the interlay spacing of LDH has been expanded. The LOI of the blend was enhanced from 18% to 21%, which revealed that the flame retardant property has been improved. In addition, the heat resistant has been improved.

Preparation of Y_2O_3∶ Nd Transparent Ceramics

HE Ting-qiu;WEN Fang;GAO Hui-huan;LEI Mu-yun;HUANG Cun-xin;SONG Qing-hai;LI Fa-hui

2009, 28(6):  1336-1339. 

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In this paper,the Y_2O_3∶ Nd nano-powders with particle size of 40-60 nm was prepared by calcination of the precursor, and Y(NO_3)_3, Nd(NO_3)_3, NH_4HCO_3 worked as raw materials. An average transmittance of infrared up to 72% of the Y_2O_3∶ Nd transparent ceramics were successfully prepared by this powders,which first molding, and then by cold isostatic pressing, through vacuum sintering and hot isostatic pressing.

Study on the Green Synthesis and Photoluminescence Property of Morphology Controllable Nano/Micro ZnO

ZHENG Ju-gong;CHEN Quan-shui;LIU Xiao-dong;YANG Ting;LIU Chong-yu

2009, 28(6):  1340-1346. 

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Using room temperature ionic liquids(RTILs)[Bmim]Cl, [Bmim]BF_4, [C_2OH]mimCl and [C_2OHmim]BF_4 as template, zinc oxide of different morphology was successfully synthesized with microwave method in Zn(OH)_4~(2-) precursor solution. The as-prepared samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM). The influence of different conditions on the morphology were also studied by SEM. The results showed that the nanometer ZnO were single crystalline with the wurtzite structure. ZnO nanoflakies, nanosheets, nanorods , nanocones, micro spherical and micro flowers were prepared with different RTILs. Preferential growth orientation along the [0001] direction became more apparent with the increasing of raw materials ratio. ZnO nanocones tend to be uniform, the crystallization is gradually improved and the length-diameter ratio is slowly raised with the temperature increasing from 80 ℃ to 95 ℃. A possible growth mechanism was also proposed to account for the formation of the multi-morphology ZnO. The photoluminescence spectra of the multi-morphology ZnO were studied at room temperature. The spectra show the sample which were prepared using RTILs as template emitted strong ultra violet emissions and relatively weak defect emissions. ZnO nanocones prepared with [Bmim]Cl as template emitted the most strong ultra violet emission peak at 387 nm. ZnO nanosheets prepared with [C_2OHmim]Cl as template generated the sharp strong green light emission peak at 387 nm.

Effect of Mechanical Alloying on the Preparation of SiO_2-Al Composite Powders

MA Zhuang;HUANG Sheng-ling;LI Wei;LI Zhi-chao

2009, 28(6):  1347-1351. 

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The impact of process control agent addition on the extraction rate and the milling time on the powders refinement, mechanical alloying and thermal stability of SiO_2-Al composite powders were studied in this paper. The composite powders after milling were analyzed by laser particle size analyzer, scanning electron microscopy, X-ray diffraction and differential thermal analyzer. The result showed that by 20 h of milling, the extraction rate of composite powders was up to 85% with adding 4% of the process control agent. With the extension of milling time, SiO_2-Al composite powders have been gradually refined, median diameter down to 4.35 μm after 20 h milling, but there is no reaction occurred. The temperature of reaction has been fallen with the extension of milling time.