Sintering of alumina and graphene powders by high-frequency induction system under a vacuum

In this study, alumina and graphene nanopowders were mixed and sintered by induction under a vacuum. In the first stage, sintering parameters were determined. 1wt.% GNP (graphene nanoplatelets) was added into alumina matrix. Al2O3-GNP nanocomposites were mixed in a V-type mixer for 2 hours at 35 cycle/min to obtain homogeneous mixtures. The mixed composites were compacted and sintered in-situ by applying uni-axial pressure in a graphite die, heated generated by the ultra high-frequency induction heated system (UHFIHS). The graphite die was heated to 1500, 1550, 1600 and 1650 oC for 5, 10 and 20 min under a vacuum. The effect of sintering temperature and time on density, surface roughness, hardness and the microstructure of in-situ sintered nano graphene-alumina compacts were investigated. In the other stage of the work, GNP nanopowder of different weights was added the alumina matrix. Al2O3-GNP composites were mixed by High Speed Ball Milling for 2 hours at 350 rpm. The mixed composites were sintered at 1650 oC for 20 min by UHFIHS. The influence of the 0 wt.% 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 %, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.% ve 5 wt.% GNP contribution on the alumina matrix was investigated.