Toughening of a Particulate‐Reinforced Ceramic‐Matrix Composite by Thermal Residual Stress

Abstract

The micromechanics involved in increased crack growth resistance, KR, due to the addition of TiBz particulate in a SIC matrix was analyzed both experimentally and theoretically. The fractography evidence, in which, the advancing crack was attracted to adjacent particulates, was attributed to the tensile region surrounding a particulate. Countering this effect is the compressive thermal residual stress, which results in the toughening of the composite, in the matrix. This thermal residual stress field in a particulate-reinforced ceramic-matrix composite is induced by the mismatch in the coefficients of thermal expansion of the matrix and the particulate when the composite is cooled from the processing to room temperature. The increase in K R of the composite over the monolithic matrix, which was measured by using a hybrid experimental-numerical analysis, was 77%, and compared well with the analytically predicted increase of 52%. The increase in K R predicted by the crack deflection model was 14%. Dependence of K R on the volume fraction of particulates, &, and of voids, fv, is also discussed. [

Spark plasma sintering (SPS) - an advanced sintering technique for structural nanocomposite materials

“…Since the pioneering work of Niihara (1991) (Golla and Basu, 2014;Yamamoto et al, 2008;He et al, 2009;Wang and Steven, 1989;Nieto, Lahiri, and Agarwal, 2012;Liu et al, 2012;Chae et al, 2006;Choa et al, 1998;Gao et al, 1999aGao et al, , 1999bTaya et al, 1990). One of the motivations for interest in SiC-reinforced composites is the toughening mechanism associated with the composites, referred to as residual stress toughening.…”

Residual Stress Measurements of Alumina-Zirconia Ceramics by Time-of-Flight Neutron Diffraction

“…The residual stresses were estimated with the modified Eshelby model proposed by Taya et al [20]. In the model, the isotropic average stress fields in the Al 2 O 3 matrix and Y-TZP particulate can be theoretically estimated from the volume fraction, elastic modulus, Poisson's ratio and thermal expansion coefficients of the phases.…”

ZrO2-Bioglass Dental Ceramics: Processing, Structural and Mechanics Characterization

“…(BASU, VLEUGELS, 2001). The residual stress in zirconia matrix was calculated according to the model proposed by Taya (TAYA et al, 1990) and confirmed by Shi (SHI et al, 2000). In the calculations we used the modulus of elasticity (E) from 90GPa to 190GPa for the Bioglass and ZrO 2 .…”

“…The calculation of the average thermal residual stress generated during cooling of the sintered samples was based on the consideration that there is homogeneous distribution of second phase in ceramic matrix ZrO 2 , and is directly related to the difference in thermal expansion coefficients between the phases in the ZrO 2 matrix and intergranular glassy phase, composed of Bioglass (TAYA et al, 1990;SHI et al, 1998). Was not taken into account the hypothesis of partial crystallization of the glass or the temperature range where there is softening of the glass present.…”