Indian Journal of Science and Technology

Abstract

Objectives: Nano sized objects are exhibiting extra ordinary potential in all the aspects of properties. Objective of this work is to develop the composite of alumina reinforced with nano sized silicon nitride particles to analyze the compression behaviour of the developed composite materials against compacting pressure and % of reinforcement. Methods: Powder metallurgical techniques were used to manufacture the sample specimens of composites. The specimens were prepared with various proportions Si3 N4 reinforcement ranges from 1 wt% to 20 wt%. Alumina was functionalized with 5 wt% of Poly Vinyl Alcohol (PVA) at 80°C using water as plasticizer to enhance the dispersion and flow behaviour essential for forming the material. The composites were cold formed in two cycles where compacting pressure was maintained as 510 MPa and 725 MPa. The sintering temperature was maintained as 1400°C for soaking period of 30 minutes. Findings: The results revealed that the reinforced composites showed 35% more compressive strength than unreinforced monolithic material. It was found that the reinforcement content of silicon nitride increased the compressive strength of the composite as expected. The barrelling behaviour was not observed during compression. The compressive strength of monolithic alumina at 725 MPa was 0.7 times greater than of 510 MPa. It was observed that 12.5% of reinforcement experienced maximum peak load of failure. The 1400°C for sintering was observed as not sufficient to make plastic flow in powder metallurgical preforms. Application/Improvements: The betterment in result can be achieved by increasing the sintering temperature to 1800°C for soaking time 30 minutes. This study reveals that this particular combination of ceramic matrix composites exhibit better results in compressive behaviour. This can be further analyzed for wear and can be used as outstanding material in hybrid ceramic bearings.

Keywords: Ceramic Matrix Composites, Compression Behaviour, Hybrid Bearings, Powder Metallurgy, PVA