Abstract

The sintering process of Metal Matrix Composites and Ceramic Varistors has been studied in this project. Metal Matrix Composites of A1/A1203 and Al-6061/SiC and ceramic ZnO varistors were manufactured through compaction and sintering process. The compressibility of A1/A1203 was studied with respect to lubrication and volume fraction of reinforcement. The effect of sintering temperature, sintering time and volume fraction of reinforcement on the compressive strength and hardness of A1/A1203 composites has been investigated. Mathematical models for hardness of A1/A1203 composites and compressive strength and hardness of Al-6061/SiC have been developed utilizing design of experiments and response surface methodology. A theoretical model for the flow stress behaviour of Metal Matrix Composites has been developed which considers the effect of the size and shape of the particles and the volume fraction of the reinforcement. For the sintering operation of zinc oxide varistors, two apparatus, one for controlling the weight loss and other for controlling the shrinkage were developed and used to obtain constant weight loss and shrinkage rates. An optimized firing profile has been established which gives higher energy capability of the product and simultaneously reduces the firing time. A mathematical model has been developed for the failure analysis of the varistors in relation to the weight loss rate and shrinkage rate. The microstructure of the samples fired by rate controlled sintering has been studied by SEM.