Mechanical properties and residual stresses in ZrB2–SiC spark plasma sintered ceramic composites

Abstract

ZrB 2-17vol%SiC, ZrB 2-32vol%SiC, and ZrB 2-45vol%SiC ultra-high temperature particulate ceramic composites were sintered using Spark Plasma Sintering (SPS). The mechanical performance of the ZrB 2-SiC composites was investigated using 4-point bending to determine their instantaneous flexural strength and fracture toughness. Resonant Ultrasound Spectroscopy was used to determine the Young's, shear, and bulk moduli as well as Poisson's ratio of all examined composites. The distribution of thermal residual stresses and the effect of applied external load on their redistribution was studied using micro-Raman spectroscopy. Piezospectroscopic coefficients were determined for all three ZrB 2-SiC ceramic composites and their experimentally obtained values were compared with the piezospectroscopic coefficients

Microstructure and indentation damage resistance of ZrB2‐20 vol.%SiC ipo‐eutectic composites

“…In present work, such anomalous crack inhibition was attributed to the hierarchical structure of DS sample where the ZrB 2 phase was under strong compression and the SiC phase was in tension. 31 The peculiarity of such behavior should be clearly attributed to the ipoeutectic structure where the SiC network surrounded the ZrB 2 matrix. As a typical brittle ceramic, ZrB 2 should exhibit cracks elongating at the diagonals of an intent.…”

Effects of SiC content on the densification, microstructure, and mechanical properties of HfB2–SiC composites

“…[28][29][30][31] This phenomenon can be witnessed by crack attraction to the second phase in case of tensile stress field present in the matrix (Figure 9). [28][29][30][31] This phenomenon can be witnessed by crack attraction to the second phase in case of tensile stress field present in the matrix (Figure 9).…”

“…Since cracks can better grow in a matrix with tensile residual stresses rather than the one with no stress, thermal residual stresses induced by thermal expansion coefficient mismatch between the matrix and the second phase may impose an increasing or decreasing effects on fracture toughness. [28][29][30][31] This phenomenon can be witnessed by crack attraction to the second phase in case of tensile stress field present in the matrix (Figure 9).…”

“…Effect of residual stress induced by second phase on composite fracture toughness has been investigated in previous studies, and Equation (2) has been commonly used for estimating the toughness change caused by the residual stress. 30,31 In this equation, ΔK residual stress denotes the change in fracture toughness (in MPa m 0.5 ) due to the residual stress, q is residual stress (in MPa) in the matrix, and d (in m) is the average spacing between adjacent particles of secondary phase. By measuring the d on SEM images, the value was obtained as about 5.6 μm for the 10-1800 samples.…”

Microstructure and mechanical properties of ZrB2-SiC composites fabricated by the centrifugal gel casting

“…As with other nonoxide ceramics, ZrB 2 would be easy to be oxidized when exposed to air under an elevated temperature, the addition of second phase SiC particles would enhance the oxidation resistance by decreasing oxidation rate of ZrB 2 [2,9,10]. Generally, ZrB 2 -SiC ceramics are usually fabricated by hot pressing or spark plasma sintering [11], which limit the fabrication of samples with relatively simple geometrical and moderate size, and requires costly and time-consuming electrical machining to obtain complex-shaped components. Recently, a great number of colloidal processing have been used to prepare near-net shaped components, such as tape casting [12], slip casting [13], centrifugal casting [14] and gel casting [15].…”