Effect of a titanium nitride interlayer on the densification, properties and microstructure of cermets based on alumina and nickel — Part 2: Microstructures
SEM microstructural analyses in conjunction with EDX and TEM microstructural analyses have been conducted with cermets based on nickel and alumina, the latter as such and with a chemical-vapour-deposited titanium nitride layer. It has been proved that there is excellent bonding at both the Al2O3/TiN and the TiN/Ni interface, whereas Al2O3 and Ni do not adhere to each other. This is the reason for the observation that the mechanical properties as well as the densification of cermets consisting of Al2O3 and Ni are enhanced by applying a TiN interlayer between the ceramic phase and the metallic phase.
Effect of a titanium nitride interlayer on the densification, properties and microstructure of cermets based on alumina and nickel — Part 1: Densification and properties
In order to manufacture cermets based on Al2O3 and Ni, Al2O3 particles were first coated with TiN by CVD and then mixed with pure Ni powder. The cermets were produced from the mixed powders by powder metallurgy processes. The relative density and the mechanical properties of the cermets are improved due to the presence of the TiN interlayer. The contribution of this interlayer to the mechanical properties of the cermets produced by hot-pressing is superior to that by pressureless sintering.
Effect of Porosity on Physical Properties of Sintered Alumina
Porous structures having a continuous solid phase with isolated pores were prepared by the addition of different amounts of crushed naphthalene to an alumina casting slip. Samples of from 5 to 50% porosity were fired together for comparable grain development, eliminating structural variables except porosity. Effects of porosity and temperature on strength, elastic modulus, modulus of rigidity, and coefficient of thermal expansion were investigated. Effects of porosity on thermal stress resistance and tor-sional creep properties were studied at constant temperature.