Strengthening oxide-oxide-free materials by incorporation of TiC‒ZrC solid solutions into their structure during plasma-spark sintering of initial powder mixtures under high compression load

Abstract

The effect of sintered TiC‒ZrC solid solutions during spark plasma sintering of com-positions at pressing loading of 60 MPa in the range 1200‒1600 ^оС on the phase composition, microstructure, relative density, open porosity, linear shrinkage, physical-mechanical properties and linear correlation of modulus of elasticity and fracture toughness of mullite‒WC‒TiC‒ZrC and mullite‒c-BN‒TiC‒ZrC samples is shown. Synthesised powders of WC, c-BN and sintered at 1800 ^оC TiC‒ZrC solid solutions by spark plasma method are characterisized by intensive crystallization of WC, c-BN and (Ti, Zr)C with uniformly, densely sintered, crystalline microstructures, respectively. Sintered samples, containing solid solutions with ratios of TiC and ZrC, equal to 80/20 and 90/10 mol. %, show intensive development of mullite and (Ti, Zr)C, graduall growing of c-BN and (Zr, Ti)C as well as decrease the intensity of WC phase in the range 1200‒1600 ^оC. Microstruc-tures of samples with c-BN and TiC‒ZrC solid solutions in different ratios more uniformly and densely sintered, crystalline, finegrained with insignificant quantity of pores, more reinforced at the boundaries areas of oxide and nonoxide crystalline phases. As a result, such samples show higher values of relative density, linear shrinkage and physical-mechanical properties in the range 1200‒1600 ^оС, higher resistance to the cracking at 1500 ^оC and larger linear correlation of modulus of elasticity and fracture toughness in the range 1200‒1600 ^оC.