Innovative Processing of HfC Coating using Hf-Containing Polymers

Refractory metal carbide coatings are important in high temperature applications by offering corrosion protection of the high temperature components. Traditional methods of producing such coatings are expensive and complex. A low temperature polymericbased process to fabricate HfC with low oxygen impurity and high yield is now ready for assessment for coating applications. The attributes of this approach are low cost, ease of control and low temperature. The emphasis of the proposed SBIR research(Phase I) is to extend the basic understanding of this polymer based approach to determine the feasibility of applying this technique to fabricate high purity HfC coatings on high temperature components, while maintaining the attributes of low cost andease of fabrication. Poco graphite was selected for the Phase I study due to its well characterized structure and commercial importance. We will demonstrate the feasibility of producing a uniform 25-micron thick HfC coating infiltrated onto porousgraphite using the processing schemes developed. The proposed Phase I will include one level of iteration for process optimization based on a correlation of microstructure with processing parameter. The resulting specimens will be assessed quantitativelyusing appropriate microstructure characterization techniques. One of the intended applications is for rocket nozzle and hot-gas valve components.Dual use applications include coatings on high temperature components for energy production systems such asturbines and compressors, aerospace systems such as thermal and oxygen barriers for reentry protection, automobile industry such as turbochargers and high temperature valves.