Chuncheng Zhu

Self-propagating high temperature synthesis of intragranular TiC-Ti3AlC2 composites

Abstract Abstract TiC-Ti3AlC2 composites with a novel intragranular structure were fabricated by self-propagating high temperature synthesis technique using Ti, Al and C elemental powders. X-ray diffraction results indicated that the as synthesised composites were composed of TiC and Ti3AlC2, where the amounts of TiC were measured to be 5·4, 9·2 and 16·7 wt-%. Transmission electron microscopy observation showed that the globular TiC was located within the plate-like Ti3AlC2 grain, which confirms the ubiquitous existence of intragranular structure in the composites.

Oxidation resistance of Co-Ni-xNiFe2O4 as potential inert anodes

Co-Ni-xNiFe2O4(x=5, 10, 15 and 20wt %) metal-based composite materials were prepared by pressureless sintering method, and were investigated for potential applications as inert anodes in aluminum electrolysis. The oxidation resistance of the as-prepared samples was experimented under air condition at 960°C. An approximately parabolic rate evolution was found in the curves of oxidized dynamics, and the oxidation rates become much slower when a compact oxide scale is formed. The oxide scales are mainly comprised of CoO·3NiO as identified by x-ray diffraction patterns (XRD). The oxide scales grow by the inward diffusion of oxygen and the simultaneous outward diffusion of nickel and cobalt ion. The surface and fracture morphologic observation of the oxidized sample was carried out by scanning electron microscope (SEM). It is found the oxide scale-substrate interface straight and there is small crack along the interface. The adhesion of oxide scale to the metal substrate is not so good. Finally it is concluded that the sample with 20wt% NiFe2O4 exhibits the best oxidation resistance by comparison.