Multiscale Damage Analysis and Experimental Study of Crack Propagation in SiC

doi:10.16552/j.cnki.issn1001-1625.2026.0157

Abstract

Abstract:

Silicon carbide （SiC） is a high-performance ceramic material with high strength， high-temperature resistance， high thermal conductivity， and excellent chemical stability. These properties make it widely used in aerospace thermal protection， nuclear structural components， and semiconductor manufacturing. However， micro-defects and mesoscale pores are inevitably introduced during fabrication， severely limiting processing efficiency and service reliability. It is therefore of considerable engineering importance to develop a reliable multiscale damage analysis method capable of bridging microscopic damage mechanisms and macroscopic fracture behavior. To this end， this study proposed a multiscale damage analysis method that integrates molecular dynamics （MD） and the cohesive zone model. The method quantitatively investigated the effects of different micro-defect configurations and porosity levels on the fracture toughness of polycrystalline SiC.

At the microscale， MD simulations were conducted using an improved Tersoff potential for β-SiC， and traction-separation （T-S） curves were obtained under both intergranular and transgranular fracture modes. The critical traction ranged from 27.77 GPa to 30.91 GPa for intergranular fracture and from 39.01 GPa to 41.86 GPa for transgranular fracture. Among the five micro-defect types， the rectangular crack consistently yielded the highest critical traction. Introducing a void along the path of a propagating rectangular crack reduced the critical traction， whereas increasing the aspect ratio of an elliptical void effectively enhanced it. Cohesive parameters， specifically maximum tensile stress， stiffness coefficient， and fracture energy， were subsequently extracted from the T-S curves via bilinear fitting and served as input for the mesoscale and macroscale models. At the mesoscale， polycrystalline models with different porosities were constructed using a bilinear boundary Voronoi diagram method. To realistically represent the porosity， circular pores with a diameter of 20 μm were uniformly embedded. The extracted cohesive parameters were assigned to zero-thickness cohesive elements inserted along grain boundaries and within grains， thereby predefining potential crack propagation paths. Based on the mesoscale models， a 2D plane-strain three-point bending finite element model was established， featuring a length of 20 mm， a width of 4 mm， and a pre-crack length of 2 mm. The simulation results indicated that， at a given porosity， the rectangular crack yielded the highest critical reaction force and fracture toughness， while the combination of the prolate elliptical void and the rectangular crack yielded the lowest. This finding was consistent with the MD results. For identical micro-defects， fracture toughness was negatively correlated with porosity. Compared with the pore-free model， the average fracture toughness decreased by 2.89% for 3% porosity and by 7.33% for 6% porosity. The predicted critical stress intensity factor ranged from 1.87 MPa·m^1/2 to 1.98 MPa·m^1/2 at 0% porosity， from 1.82 MPa·m^1/2 to 1.92 MPa·m^1/2 at 3% porosity， and from 1.73 MPa·m^1/2 to 1.87 MPa·m^1/2 at 6% porosity. Finally， three-point bending tests were performed on SiC specimens with 3% porosity. The experimental results show an average critical reaction force of 10.60 N and an average fracture toughness of 1.93 MPa·m^1/2. The maximum deviation between the experimental and simulated fracture toughness was 8.63%， confirming the accuracy of the proposed method.

Overall， the proposed method provides an effective tool for fracture assessment and reliability-oriented design of SiC and related ceramic components. In particular， it offers guidance for optimizing porosity and micro-defect configuration during processing， and enables evaluation of the influence of these factors on structural fracture toughness at the material design stage， thereby helping reduce the risk of catastrophic fracture failure. Future work will incorporate more realistic pore morphologies， processing-induced heterogeneity， and multiphase effects to further extend the applicability of the method to more complex ceramic materials.

Key words: silicon carbide, Voronoi diagram, crack propagation, molecular dynamics simulation, cohesive zone model

CLC Number:

TB321

FENG Boping, YU Puliang, MU Zelong, LIU Yuanjiong, DING Xin, WU Jiulin. Multiscale Damage Analysis and Experimental Study of Crack Propagation in SiC[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(8): 2863-2875.

Figures/Tables 17

Fig.1 Unit cell structure of β-SiC

Fig.2 MD models containing different micro-defects

Fig.3 Bilinear cohesive constitutive model

Fig.4 Schematic diagram of Voronoi polygon with bilinear boundaries

Fig.5 Schematic diagrams of polycrystalline models

Fig.6 Three-point bending FE model

Fig.7 T?S curve and crack propagation process of 25 ??spaced circular void?rectangular crack micro?defect MD model under intergranular fracture

Fig.8 T?S curve and crack propagation process of 25 ??spaced circular void?rectangular crack micro?defect MD model under transgranular fracture

Table 1 Cohesive parameters

	Model	Micro-defect	Maximum tensile stress/GPa	Maximum separation/Å	Stiffness coefficient/（10¹⁹ N·m^-3）	Fracture energy/（J·m^-2）
Intergranular fracture	A	Rectangular crack	30.91	22.63	19.49	34.98
	B	Prolate elliptical void-rectangular crack	27.77	21.92	18.24	30.43
	C	25 Å-spaced circular void-rectangular crack	27.79	21.98	17.69	30.54
	D	Oblate elliptical void-rectangular crack	28.70	22.27	18.28	31.96
	E	30 Å-spaced circular void-rectangular crack	27.80	21.88	19.92	30.42
Transgranular fracture	A	Rectangular crack	41.86	29.21	20.37	61.12
	B	Prolate elliptical void-rectangular crack	39.01	27.83	21.00	54.28
	C	25 Å-spaced circular void-rectangular crack	40.36	28.94	20.35	58.40
	D	Oblate elliptical void-rectangular crack	40.86	30.36	20.41	62.07
	E	30 Å-spaced circular void-rectangular crack	40.43	28.62	20.15	57.86

Fig.9 Three-point bending FE models

Fig.10 Crack propagation process in three-point bending FE model under 25 ??spaced circular void-rectangular crack micro-defect condition

Fig.11 Reaction force-displacement curves for models with different porosities under various micro?defect conditions

Fig.12 Influence of porosity variation on material fracture toughness under different micro?defect conditions

Table 2 Dimension parameters of specimens

Specimen	Specimen width/mm	Specimen height/mm	Pre-crack length/mm	Relative length of crack
1	3.21	4.23	1.82	0.43
2	3.42	4.34	1.70	0.39
3	3.32	4.31	1.53	0.35
4	3.27	4.30	1.60	0.37
5	3.19	4.26	1.68	0.39

Fig.13 Three?point bending experimental platform

Fig.14 Reaction force-displacement curves

Fig.15 Fracture toughness comparison

References 26

[1]	WANG S D， LI Z C， LEI M P， et al. Preparation of a novel eutectic Si-Nd brazing filler for high-temperature welding SiC ceramics via electromagnetic oriented crystallization［J］. Ceramics International， 2025， 51（30）： 64061-64071.
[2]	YANG F， CHEN Y H， HAI W X， et al. Research progress on high-thermal-conductivity silicon carbide ceramics［J］. Ceramics International， 2025， 51（4）： 4095-4109.
[3]	WU N X， LIU D L， ZHONG M J， et al. Analysis of crystal structure transition of polycrystalline 3C-SiC in nanocrystalline grinding based on molecular dynamics simulation［J］. Solid State Ionics， 2023， 399： 116297.
[4]	TERRANI K A， KIGGANS J O， SILVA C M， et al. Progress on matrix SiC processing and properties for fully ceramic microencapsulated fuel form［J］. Journal of Nuclear Materials， 2015， 457： 9-17.
[5]	FENG D K， LIU Z H， WU X S， et al. Enhancement of mechanical properties and reliability of SiC ceramics by depositing a pre-stressed SiC coating［J］. Ceramics International， 2026， 52（7）： 8936-8945.
[6]	李辰冉，谢志鹏，康国兴，等. 国内外碳化硅陶瓷材料研究与应用进展［J］. 硅酸盐通报， 2020， 39（5）： 1353-1370.
	LI C R， XIE Z P， KANG G X， et al. Research and application progress of SiC ceramics： a review［J］. Bulletin of the Chinese Ceramic Society， 2020， 39（5）： 1353-1370 （in Chinese）.
[7]	周小楠，张建飞，黄鑫，等. 多孔重结晶碳化硅陶瓷的烧结颈结构调控与力学性能［J］. 硅酸盐学报， 2019， 47（9）： 1208-1213.
	ZHOU X N， ZHANG J F， HUANG X， et al. Mechanical properties of porous recrystallized SiC ceramics with taliored neck between SiC grains［J］. Journal of the Chinese Ceramic Society， 2019， 47（9）： 1208-1213 （in Chinese）.
[8]	王锋，曾宇平. 多孔SiC陶瓷制备工艺研究进展［J］. 现代技术陶瓷， 2017， 38（6）： 412-425.
	WANG F， ZENG Y P. Research progress of the processing methods for porous SiC ceramics［J］. Advanced Ceramics， 2017， 38（6）： 412-425 （in Chinese）.
[9]	ZHANG J Q， WANG F. Modeling of progressive failure in ductile matrix composites including local matrix yielding［J］. Mechanics of Advanced Materials and Structures， 2009， 16（7）： 522-535.
[10]	LU M， WANG F， ZENG X G， et al. Cohesive zone modeling for crack propagation in polycrystalline NiTi alloys using molecular dynamics［J］. Theoretical and Applied Fracture Mechanics， 2020， 105： 102402.
[11]	XU X P， NEEDLEMAN A. Numerical simulations of fast crack growth in brittle solids［J］. Journal of the Mechanics and Physics of Solids， 1994， 42（9）： 1397-1434.
[12]	ALI M， HEADINGS L M， SRINIVAS V， et al. Laminated interface characterization and cohesive zone modeling （CZM） of fracture for ultrasonic additive manufacturing （UAM） structures［J］. Journal of Manufacturing Processes， 2025， 154： 614-622.
[13]	ZHOU T T， HUANG C Z. Simulation of crack propagation in single phase ceramic tool materials［J］. Computational Materials Science， 2015， 104： 177-184.
[14]	ZHOU X W， MOODY N R， JONES R E， et al. Molecular-dynamics-based cohesive zone law for brittle interfacial fracture under mixed loading conditions： effects of elastic constant mismatch［J］. Acta Materialia， 2009， 57（16）： 4671-4686.
[15]	YU M J， DUAN F L. Cross-scale method of MD-FE for modeling mechanical damage behaviors of ferrite-cementite steels［J］. Engineering Fracture Mechanics， 2024， 302： 110077.
[16]	DING J， ZHENG H R， TIAN Y， et al. Multi-scale numerical simulation of fracture behavior of nickel-aluminum alloy by coupled molecular dynamics and cohesive finite element method （CFEM）［J］. Theoretical and Applied Fracture Mechanics， 2020， 109： 102735.
[17]	YU P L， ZHONG M， WU L H， et al. Multi scale simulation of crack propagation in polycrystalline SiC［J］. Theoretical and Applied Fracture Mechanics， 2024， 129： 104231.
[18]	宗亮，许晓静，周海. β-SiC单晶块体拉伸变形行为分子动力学研究［J］. 计算物理， 2010， 27（6）： 898-904.
	ZONG L， XU X J， ZHOU H. Molecular dynamics simulation of tension deformation in monocrystalline β-SiC bulk［J］. Chinese Journal of Computational Physics， 2010， 27（6）： 898-904 （in Chinese）.
[19]	ERHART P， ALBE K. Analytical potential for atomistic simulations of silicon， carbon， and silicon carbide［J］. Physical Review B， 2005， 71（3）： 035211.
[20]	SHENG Y， ZENG X G. The deformation mechanisms in process of crack propagation for alpha titanium with compounding microdefects［J］. Advances in Materials Science and Engineering， 2016： 2156936.
[21]	FU T， PENG X H， HUANG C， et al. Strain rate dependence of tension and compression behavior in nano-polycrystalline vanadium nitride［J］. Ceramics International， 2017， 43（15）： 11635-11641.
[22]	李增伟，侯泽伟，洪家旺，等. 基于内聚力模型的某型挂钩悬挂失效分析［J］. 中国机械工程， 2025， 36（9）： 1934-1941.
	LI Z W， HOU Z W， HONG J W， et al. Failure analysis of a certain type of hook suspension based on cohesive zone model［J］. China Mechanical Engineering， 2025， 36（9）： 1934-1941 （in Chinese）.
[23]	MI Y， CRISFIELD M A， DAVIES G A O， et al. Progressive delamination using interface elements［J］. Journal of Composite Materials， 1998， 32（14）： 1246-1272.
[24]	AURENHAMMER F. Voronoi diagrams： a survey of a fundamental geometric data structure［J］. ACM Computing Surveys， 1991， 23（3）： 345-405.
[25]	ZHU Y J， WANG L， ZHANG Z Q， et al. Simulation and experimental study on the self-sharpening mechanism of polycrystalline cBN abrasive grit based on Voronoi diagram［J］. Journal of Materials Research and Technology， 2026， 40： 2732-2747.
[26]	国家市场监督管理总局，国家标准化管理委员会. 精细陶瓷断裂韧性试验方法单边预裂纹梁（SEPB）法：GB/T 23806—2025 ［S］. 北京：中国标准出版社， 2025： 11.
	State Administration for Market Regulation， National Standardization Administration. Test method for fracture toughness of fine ceramics at room temperature-single edge precracked beam （SEPB） method：GB/T 23806—2025 ［S］. Beijing： Standards Press of China， 2025： 11 （in Chinese）.