Microwave-Based Diamond Deposition Process for Coating of Materials

This proposed effort utilizes an existing DoD technology, known as a traveling wave tube (TWT), as a broadband, high-power plasma source. The TWT will permit optimization of processing parameters over a frequency range larger and wider than has previously been examined and will allow optimum, real-time control of the process parameters. This source technology will be combined with a water-based diamond deposition chemistry, which offers considerable advantages over traditional hydrogen-methan chemistries in both safety and manufacturing cost. The goal of this proposed effort is to develop a TWT-based flexible diamond manufacturing process tool. Previous work by MLI -- in cooperation with the Research Triangle Institute -- has already demonstrated that TWTs can be used to generate high-freqency, microwave-excited plasmas for diamond deposition at fixed frequencies. This Phase I effort will demonstrate controlled, variable-frequency operation. This proposed effort will couple microwave energy from a TWT into a cylindrical cavity and use variable frequency operation to raster the plasma along the surface of a carbon composite sample -- thereby demonstrating the feasibility of controlling the efficienty deposition of diamond films over unique geometries. Anticipated Benefits: Diamond films have properties -- e.g., thermal conductivity, chemical inertness, abrasion resistane -- which meet the requirements of a variety of military, space, and commercial applications: scratch-resistant coatings, wear-resistant high-speed bearings, heat sinks and thermal management devices, and anti-corrosion protection. Successful demonstration of plasma spatial rastering has the potential to revolutionize many CVD and CVI technologies and processes.