Mechanical Properties of Chemical-Vapor-Deposited Silicon Carbide using a Nanoindentation Technique

Abstract

The mechanical properties of silicon carbide deposited by chemical vapor deposition process onto a graphite substrate are studied using nanoindentation techniques. The silicon carbide coating was fabricated in a chemical vapor deposition process with different microstructures and thicknesses. A nanoindentation technique is preferred because it provides a reliable means to measure the mechanical properties with continuous load-displacement recording. Thus, a detailed nanoindentation study of silicon carbide coatings on graphite structures was conducted using a specialized specimen preparation technique. The mechanical properties of the modulus, hardness and toughness were characterized. Silicon carbide deposited at 1300oC has the following values: E=316 GPa, H=29 GPa, and K c=9.8MPa m1/2; additionally, silicon carbide deposited at 1350oC shows E=283 GPa, H=23 GPa, and K c=6.1MPa m1/2. The mechanical properties of two grades of SiC coating with different microstructures and thicknesses are discussed.