Abstract
Abstract : The erosion-wear behaviour of spark plasma sintered austenitic stainless steels matrix composites was investigated under high temperature conditions. As-received powders were characterized using SEM-EDS and XRD. Powders were mixed at varying compositions of austenitic steels/titanium nitride and the admixed powders were characterized using SEM-EDS and XRD to check if the samples have been homogeneously mixed. Size determination was conducted on the feedstock powders by a Particle Size Distribution method. The homogeneously mixed powders were then sintered at 1100 oC with a heating rate of a 100 oC/min, applied vacuum pressure of 50 MPa and holding time of 10 minutes. The study involved metallagraphic preparation of sintered solid specimen, microstructural characterization of consolidated austenitic stainless steel under SEM-EDS and phase identification analysis under XRD. Erosionwear behaviour of the composites was conducted at a constant velocity of 18 m/s at temperatures from room temperature, 400 oC, up to 600 oC. The material used as the erodent was abrasive alumina particles with particle size of 40 μm. The incident angle of 90o was employed throughout. After SPS, it was observed that the relative density of spark plasma sintered samples decreased with increasing TiN content. The erosion wear rate indicates that there is a proportional relationship between the decreasing percentage of hardness and the erosion rate. The results further indicate that material wastage increases with increasing temperature. XRD reveal that there is a new phase (B2: AlNi) formed after erosion. Microstructures indicate that the erosion damage occurs mainly by plastic deformation and brittle fracture. Macrographs of the eroded specimens show three layers in which the first (central) layer represents high material loss, the v second layer where lesser amount of material wastage is experienced and the third (outer) layer where the least amount of material was removed.
M.Tech. (Chemical Engineering)