INVESTIGATION ON COMPRESSIBILITY OF NANOCOM.POSITE ALUMINA POWDERS AND INFLUENCE OF PAR1ICLE SIZE

Abstract

Alumina ceramics are chosen primarily for their extremely high hardness values in addition to wear and corrosion resistance. Most commonly used alumina are alpha alumina which are stable. Beta, gamma and delta alumina are metastable. Alpha alumina may be reinforced with gamma nano alumina to further increase its hardness. Consolidation of their nanocomposite samples at very high temperature leads to very high hardness required for many applications. If the hardness of alumina nanocomposite is very high then its long term application as mortar-pestles, crucibles, tubes, floor tiles, insulators, substrates, and sanitary ware etc. is justified. In this dissertation work, the samples of ceramic nanocomposite were made. Alpha alumina (A1203) powders of submicron and micron size particles were taken as matrix material and gamma alumina powder of nano size particles was taken as particulate. The samples were prepared by cold uniaxial die compaction method by varying the ap[)lied load and amount of the nanocomposite powder. It was then followed by solid state sintering at two different high temperatures. The SEM studies were carried out and microstructural features attempted to correlate with the properties and results. The hardness of the samples was measured by narioindentation using Hysitron triboindentor.