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Abstract
Different types of silicon carbide powders, with a few amount of boron and carbon
as sintering additives have been investigated. The powder blends were wet mixed with
ethanol and ceramic balls in polyethylene, and glass bottles by a rotational mixer for 24
hours. All powders were dried in a furnace at temperatures 80-120 QC and screened
through a 60 mesh sieve. Flat pellets were uniaxially pressed in a stainless steel die at
pressures 120-190 MPa. Other specimens are cold isostatically pressed under 350 MPa into
cylindrical shape with specific dimensions for investigating some mechanical, thermal, and
electrical properties.
Some specimens are pressureless sintered using 1800-2200 QC, and 10-120 minutes
as a holding time in argon atmosphere. Other specimens were sintered using hot isostatic
pressure (HIPing) with 1800 QC and 300 MPa argon pressure. Also the specimens are
infiltrated with molten silicon under vacuum and 1450 QC for 150-180 minutes. The
relationship hetween sintering temperatures and some physical parameters such as; mass
losses, relative densities, fracture toughness, and microhardness of different SiC types at
different sintering temperatures were investigated. The surface of specimens were polished
and chemically etched before the microstructure investigations. Microstructure, x-ray
diffractions, thermogravimeteric analysis, and chemical analysis were done for the different
types of silicon carbide. A large numbers of the different specimens with different
compositions were tested 10 the electron beam facility JUDITH with different pulse
durations, and energy densities among 1.15 to 11.3 MJ/m2. The specimens after the testing.