Evaluation of Mechanical Properties of High-Toughness Multilayered Diamond Films

When diamond is used as a wear-resistant material for tools, its unique wear resistance cannot be fully exploited due to the possibility of brittle fracture. In general, diamond films synthesized by the vapor phase method are polycrystalline and exhibit columnar crystal growth. In the polycrystalline structure, once cracks occur on the surface of the film, they tend to propagate through the columnar particles, leading to decreased toughness. The authors succeeded in synthesizing multilayered diamond films by repeated application of the bias-enhanced hot filament method. The multilayered films were superior in surface roughness, and the bending strength of the film was approximately 30% higher than that of a conventionally produced diamond film. In this study, we synthesized multilayered diamond film by the hot filament method using a WC-Co alloy substrate, and evaluated the adhesion strength for use in anti-wear parts.