SBIR Phase II: Nanocrystalline Diamond Coated Cutting Tools

This Small Business Innovation Research (SBIR) Phase II project will develop nanocrystalline diamond coatings on tungsten-carbide cutting tools with technical attributes that surpass the current generation of chemical vapor deposited (CVD) diamond coatings as well as tools made from polycrystalline diamond (PCD) wafers. The problem with CVD diamond coatings for cutting tools is poor surface finish and weak adhesion. Nanocrystalline CVD diamond deposited using microwave plasma (MP) techniques overcomes these problems with a smooth finish that is well adhered. This makes the nanocrystalline diamond a potential competitor to PCD diamond by lowering the price and increasing productivity. The research proposed for Phase II will use a 30kW MP-CVD reactor to investigate the relationships between nanocrystalline structure and technical performance. The structure will be controlled by process variables. Technical performance will be measured by mechanical testing and field testing on the proposed target application of machining cast aluminum-silicon alloy. The anticipated technical result will be direct correlations between structure, properties and performance that can be used to optimize nanocrystalline diamond coatings for machining automotive drive-train components. Commercial applications of nanocrystalline diamond coatings are far reaching due to applications in the cutting tool industry that promote the use of hard-to-finish advanced materials; applications in pulp and paper for cutting and guides, applications in textiles for guides and applications in various bearing surface applications such as deep-well oil drill-head bearings. The National Institute of Health is also sponsoring research on nanocrystalline diamond applications in biomedical hardware surfaces subject to wear. Additionally, environmental impact of cutting fluid and related waste from machining processes are driving manufacturers to implement dry machining processes. MP-CVD nanocrystalline diamond tooling is the ideal tool for dry machining nonferrous materials.