| abstract |
A binderless coarse-grained WC substrate is coated with a chemical vapor deposition ("CVD") diamond layer in order to give a coating with improved adherence relative to WC-Co-based substrates and high compressive residual stress relative to Si3N4-based substrates. The elimination of Co from the WC improves the adherence of the diamond coating, allowing thicker coatings to be produced than for WC-Co substrates. Thin coatings (<30 mu m) are acceptable for applications where the coating is under low applied stress. Thicker coatings (>30 mu m) are used to give enhanced damage resistance for stresses localized at the surface of the diamond-coated component. Applying the diamond coating to a WC/WC-Al2O3/WC graded composite allows materials with high damage resistance to be fabricated. Deposition of a substantially continuous diamond film may be accomplished by CVD and PVD techniques. WC ceramics allow faster deposition rates since Co in WC-Co enhances back-conversion of diamond to graphite, and diamond can therefore be deposited on WC at higher temperatures than WC-Co substrates. |