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Response of silicon carbide to high-intensity laser irradiation in a high-pressure inert gas atmosphere
Published online by Cambridge University Press: 31 January 2011
Abstract
α–SiC (hexagonal) pressed powder targets were heated with a highly focused beam of CO2 laser radiation to temperatures in excess of 3200 °C in an oxygen- and water-free argon atmosphere. The argon pressure was maintained at greater than 100 atm to prevent vaporization of any liquid formed. This pressure was estimated to be several times greater than the total vapor pressure above a liquid solution of carbon and silicon. After a 30 s period at temperature, the heating was abruptly terminated. The 1 mm diameter region most affected on the surface of the SiC targets consisted of a central crater from which all SiC had been vaporized. The crater walls consisted of an amorphous carbon phase which acted as a matrix for fibrous graphite and granular silicon. Beyond the crater wall, the microstructure changed to that of various polytypes of hexagonal SiC, with the grains being equiaxed and smaller than those of the starting SiC powder, an indication that melting, followed by formation of a finer grain structure on abrupt cooling, may have occurred. Still farther from the crater, the microstructure was characterized by β-silicon (cubic) particles of spherical morphology and of larger size than the starting SiC powder, a response typical of solid state sintering. Even further from the crater, the structure was α-SiC, and the grain size was nearly the same as that of the starting material. The particles were lightly bonded together at points of contact between them, indicating only light sintering.
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- Copyright © Materials Research Society 1997
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