Powder metallurgy process towards functional gradation of Al-Al2O3 metal ceramic mixture samples

Abstract

Functionally graded materials (FGM) belong to the class of advanced materials whose properties vary along one or more coordinate. In the present study, an attempt has been made to manufacture FGM beams using a powder metallurgy process. The Al and Al<inf>2</inf>O<inf>3</inf> in powder form are mixed to different volume fraction according to the rule of mixture. These samples are ball milled to form a proper blended mixture and to reduce the particle size for 1 hour at 250 rpm with tungsten carbide balls. A cold compacted die made of AISI D2 steel is used for preparing the sample. Different composition of Al and Al<inf>2</inf>O<inf>3</inf> with Al<inf>2</inf>O<inf>3</inf> varying from 0 to 10% is laid in the die using ethanol as the binder. This sample is compressed using hydraulic press with a load varying from 50-70 ton. The compressed sample is removed using a compression moulding machine, then it is sintered to a temperature of 650°C using a muffle furnace to form a smooth graded Al-Al<inf>2</inf>O<inf>3</inf> FGM beam. Various defects such as surface cracks and bending were experienced during the preparation of samples; these defects were overcome by varying the parameters such as loading and sintering temperature. © 2019 IOP Publishing Ltd. All rights reserved.