SBIR Phase I:Improving the Adhesion of Nanocarystalline Diamond Films to Tungsten Carbide Micro End Mills

This Small Business Innovation Research (SBIR) Phase I project aims to improve the adhesion of nanocrystalline diamond coatings to micro-scale tungsten carbide cutting tools. Nanocrystalline diamond coatings have been shown to dramatically improve the machining performance of micro end mills. However, standard diamond growth methods result in weakened tool material and the coatings suffer from premature delamination, resulting in tool failure. The improved adhesion of the nanocrystalline diamond coatings will be achieved by implementing a new surface preparation technique that eliminates the need of acid etching which weakens the tool material, and seeding of nano-diamond particles which do not bond very strongly with the tool. Machining tests will be conducted to quantify the improvement in tool life, hence coating adhesion, with the new surface preparation technique. The broader/commercial impact of this project will be the potential to provide a new surface preparation technique that can be integrated with standard chemical vapor deposition systems to allow for high throughput and more economical diamond coatings for industrial applications. Diamond coated micro end mills are in demand to improve machining performance and enable the machining of products from otherwise un-machinable materials. The improved cutting performance of micro end mills by diamond coatings can only be realized if it is thin enough to not significantly alter the tool geometry and it strongly adheres to the substrate. The objective of this project is to address these challenges by developing continuous diamond coatings less than 100 nanometers thick for micro tools and a method to prevent premature coating delamination.