Surface Cracks of Solid-phase-sintered Silicon Carbide Ceramics and Their Influeces on Material Strength

doi:10.3724/SP.J.1077.2014.13429

Abstract

Abstract: The effects of surface cracks on bending strength of Solid-phase-sintered Silicon Carbide Ceramic (SSiC) were systematically investigated in aspects of crack size and inclined angle. The relation between the surface cracks and material strength revealed that the Vickers crack size is about 10 μm after 0.5 N indentation load that begins to dominant the fracture of SSiC test bars. Vickers cracks no larger than 3 μm are safe and do not harm to the general bending strength. It is found that inclined Knoop crack after 5 N or above is easier to deflect from the original direction and dominates the sample fracture process. And the relationship between the flexure strength σ and inclined angle θ is found to correspond with σ∝(sinθ)-1/2. When the indentation load is smaller than 1–2 N, Knoop crack plays a similar effect as intrinsic defect that they randomly dominate the sample fracture process; and this randomness makes the impact of inclined angle on the flexure strength irregularly.

Key words: ceramic, surface crack, inclined angle, bending strength

CLC Number:

TQ174

YANG Xiao, LIU Xue-Jian, HUANG Zheng-Ren. Surface Cracks of Solid-phase-sintered Silicon Carbide Ceramics and Their Influeces on Material Strength[J]. Journal of Inorganic Materials, 2014, 29(4): 438-442.

References

[1] ZIMMERMANN André，HOFFMAN Mark，FLINN Brian D，et al. Fracture of alumina with controlled pores. Journal of the American Ceramic Society, 1998, 81(9): 2449–2457.

[2] BARATTA F I. Refinement of stress intensity factor estimates for a peripherally cracked spherical void and a hemispherical surface pit. Journal of the American Ceramic Society, 1981, 64(1): C3–C4.

[3] FLINN B D, BORDIA R K, ZIMMERMANN A, et al. Evolution of defect size and strength of porous alumina during sintering. Journal of the European Ceramic Society, 2000, 20(14/15): 2561–2568.

[4] SUZUKi K, TANAKA K. Prediction of fracture strength of ceramics with small defects based on R-curve method. JSME International Journal. Ser. A, Mechanics and Material Engineering, 1995, 38(3): 347–354.

[5] YANG XIAO, LIU XUE JIAN, HUANG ZHENG REN, et al. Effects of Vickers cracks on the mechanical properties of solid-phase-sintered silicon carbide ceramics. Journal of Inorganic Materials, 2012, 27(9): 965–969.

[6] YANG Z, LU Z, ZHAO Y P. Atomistic simulation on size-dependent yield strength and defects evolution of metal nanowires. Computational Materials Science, 2009, 46(1): 142–150.

[7] ANDERSONS J, PORI?E E, SP?RNI?? E. The effect of mechanical defects on the strength distribution of elementary flax fibres. Composites Science and Technology, 2009, 69(13): 2152–2157.

[8] SATO T, TSUJI K, KAWASHIMA N, et al. Effect of defect size on fracture strength of dental low fusion porcelain. Colloids and Surfaces B: Biointerfaces, 2004, 38(1/2): 77-82.

[9] LAWN B. Fracture of Brittle Solids. Beijing: Senior Education Press. 2010: 201.

[10] DANZER R, SUPANCLE P, PASCUAL J, et al. Fracture statistics of ceramics - Weibull statistics and deviations from Weibull statistics. Engineering Fracture Mechanics, 2007, 74(18): 2919–2932.

[11] RYCROFT C H, BOUCHBINDER E. Fracture toughness of metallic glasses: annealing-induced embrittlement. Phys. Rev. Lett., 2012, 109(19): 194301–1–5.

[12] GARCIA-PRIETO A, BAUDIN C. Influence of experimental variables on fracture toughness determined on SEVNB in three points bending. Mullite a case study. Journal of the European Ceramic Society, 2012, 32(16): 4241–4248.

[13] LIU GUILING, HUANG ZHENGREN, LIU XUEJIAN, et al. Recent developments of surface coatings and optical fabrication of silicon carbide. Journal of Inorganic Material, 2007, 22(5): 769–774.

[14] SHE JIHONG, JIANG DONGLIANG. Development and application of silicon carbide ceramics. Ceramic Engineering, 1998, 32(3):3–11

[15] EVANS A G, CHARLES E A. Fracture toughness determinations by Indentation. Journal of America Ceramic Society, 1976, 59(7/8): 371–372.

[16] NIIHARA K, MORENA R, HASSELMAN D P H. Evaluation of KIc of brittle solids by the indentation method with low crack-to-indent ratios. Journal of Material Science Letter, 1982, 1(1): 13–16.

[17] GONG J, WU J, GUAN Z. Examination of the indentation size effect in low-load vickers hardness testing of ceramics. Journal of the European Ceramic Society, 1999, 19(15): 2625–2631.

[18] GONG J, WU J, GUAN Z. Analysis of the indentation size effect on the apparent hardness for ceramics. Materials Letters, 1999, 38(3): 197–201.

[19] YANG X, LIU X, HUANG Z, et al. Vickers indentation crack analysis of solid-phase-sintered silicon carbide ceramics. Ceramics International, 2013, 39(1): 841–845.