Temperature dependence of elastic properties of ZrB2–SiC composites

Abstract

Elastic properties (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) of ZrB 2 , SiC ceramics and ZrB 2-SiC ultra high temperature ceramic composites were measured by impulse excitation technique in the RT-1173 K temperature range. Two compositions of ZrB 2 with 17 vol% and 32 vol% of SiC strengthening phase were hot pressed to almost full density, followed by machining before the measurements took place. The temperature dependences of elastic properties have shown the expected softening behavior, where only small 4% and 5% linear reduction in Young's and shear moduli were detected, respectively, for ZrB 2-17 vol% SiC and ZrB 2-32 vol% SiC ceramic composites. The reported decrease in elastic moduli brings the respective linear increase of Poisson's ratio up to ~9% in the temperature of interest. Such high temperature behavior corresponds well to the upper and lower bounds of elastic moduli of two ZrB 2-SiC ceramic composites calculated by Voigt and Reuss estimations using properties of pure ZrB 2 and pure SiC ceramics, as published in the literature.

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

“…For comparison, the theoretical values of the average thermal residual stresses were calculated using Eqn. (4) [39], and the elastic properties of pure ZrB 2 and pure SiC reported in [6]:…”

“…Therefore, the evolution of residual stresses, their redistribution as a function of applied stress, as well as the characterization of the residual stresses itself are critical issues in the design and operation of ZrB 2 -SiC composites. The appearance of residual microstresses in the as-processed ZrB 2 -SiC composite is explained by the mismatch in Young's moduli (E) and CTE () between ZrB 2 (E=520 GPa, = 7.49x10 -6 K -1 ) [6,7] and 6H-SiC (E= 410 GPa, =5.07x10 -6 K -1 ) [5,6], as well as the difference between room temperature (20C) and the sintering temperature (typically at ~ 1950C) of the composite [8]. The cooling of the composite from the sintering temperature will induce a uniform compressive stress within the SiC grains and the radial and tangential stresses within ZrB 2 -SiC interface [9].…”

Dynamic compressive response of zirconium diboride‐silicon carbide composites at high‐strain rates

“…In Equation (), Young's modulus of the ZrB 2 –20%SiC ceramic composite is taken as E = 450 GPa . The quasi‐static compressive strength σ 0 = 1819 MPa is substituted to calculate the transition strain rate.…”

“…It is also noted that the increasing investigations on high‐temperature mechanical properties of ZrB 2 ‐based UHTC composites have been reported. Cheng, Zou, Bird, Lugovy, and Neuman, have studied the flexure strength of ZrB 2 ‐based ceramic composites at high temperatures using the three‐point bending test. Their investigations declare that the flexure strength and stiffness have little reduction below 1000°C, but serious decrease above 1500°C.…”

2D Raman mapping and thermal residual stresses in SiC grains of ZrB2–SiC ceramic composites

“…A number of theoretical calculations have been developed to estimate the thermal residual stresses. These theoretical calculations require knowledge of certain properties of the composites as shown in Table 1 [5].…”