Study of reaction-bonded silicon carbide samples using visual-optical and radiographic methods of nondestructive control

Abstract

Products based on silicon carbide are widely used in different industrial applications due to a high level of their mechanical, thermal, and operational properties. When the reaction sintering procedure is used to obtain silicon carbide materials, the preformed porous samples consisting of silicon carbide powders, carbon filler, and coke binder are subjected to liquid-phase silicizing (silicon melt infiltration (MI) in a vacuum furnace. We present the results of studying samples of reaction-bonded silicon carbide (RBSC) using visual-optical and radiographic methods of non-destructive control. Silicizing of carbon-silicon carbide materials can result in formation of defects on their surface and in the bulk of the material. The visual-optical method is shown to be rather simple and extremely informative procedure which ensures the detection of surface defects in the form of pores, cracks, chips, shells, and can also provide indirect indications of possible presence of internal defects in the form of underimpregnated areas. The samples silicized with a larger number of silicon drops on their surface exhibit a higher density and a smaller number of underimpregnated areas which can be detected using radiographic control. X-ray control carried out for several exposures differing in the angle of sample rotation by 90° provided 95%-probability of detecting internal volumetric and planar defects. The results obtained can be used in the manufacture of RBSC-based parts of tribotechnical duty, shut-off valves and other wear-resistant products.