Preparation of Aluminium-Silver Composite Cutting Tool by Chemical Synthesis

Abstract

The present work is aimed to develop metal toughened aluminium-silver composite which will be used as a cutting tool material. Chemical synthesis using the sol-gel method was carried-out to prepare alumina powder from aluminium nitrate Al (NO ) ,9H O. Then AgNO was well mixed with the prepared α-Al O powder in aqueous solution followed by 3 3 2 3 2 3 evaporation and heating, to get 10 volume percent of Ag in the Al O -Ag mixture. A conventional powder metallurgical 2 3 route was followed to prepare Al O -Ag composite pellets. The pellets were first dried at 500°C for 2 hours to burn off 2 3 the PVA, then pre-sintered at 950°C for 2 hours and finally sintered at 1600°C for 2 hours as soaking time in a furnace. XRD test shows that the phase present in the powder heated at 1600°C for 2 hours is α-alumina and only silver is present in the developed pellet as a second phase. Bulk density and open porosity of the samples were measured using Archimedes principle and employing boiling water method. Bulk densities of some of the composite pellets were found nearly 3 g/cc. Attempt should be made to improve the density in order to use the developed powder as cutting tool material. Ceramic cutting tools can be used in metal cutting, and can keep their hardness, strength, abrasion resistance and long performance life under high cutting speed. With these special mechanical properties, ceramic cutting tools will certainly substitute high speed steel cutting tools in many fields.