A Review of the Characteristics of Synthetic Diamond Coatings Prepared by Chemical Vapor Deposition (CVD) Technique

Diamond has unique properties compared to other materials. Despite these features, its application in the industry is minimal due to its scarcity and high price. Due to recent technological advances, it has become possible to deposit thin synthetic diamond coatings on the surface of various substrates such as metal and ceramics. For example, tungsten carbide–cobalt composites (WC-Co) are common materials in tribological applications and cutting tools that synthetic diamond coatings can be deposited on them. Reports in this field show that the deposition of synthetic diamond coatings by chemical vapor deposition (CVD) on the surface of carbide tools significantly improves their mechanical and tribological properties and leads to improved performance. The industrial use of synthetic diamond coatings has increased due to high wear resistance, excellent hardness, and low friction coefficient. For this reason, extensive research has been done to eliminate defects, improve the properties, and expand this category of coatings. However, one of the significant problems of synthetic diamond coatings is their low adhesion strength on the tool surfaces; Therefore, many researchers have focused on increasing the adhesion of these coatings. To achieve proper adhesion in these coatings, many characteristics of the coating-substrate system, such as the optimal thickness of the coating and minimizing the residual thermal stress, must be considered. Therefore, to attain synthetic diamond coatings with unique properties, it is necessary to design the microstructure and architecture of the coatings carefully. This article aims to review the researches conducted to improve the performance of diamond protective coatings.