Chemical Vapor Deposition (CVD) Barrel Coating for Refractory Fasteners.
Abstract
The report discusses the development of chemical vapor deposition (CVD) coating refractory processes and practical production equipment for applying these coatings to large quantities of small parts. The trideposition reaction with hydrogen reduction of gas phase silicon, titanium and chromium chloride feeds was demonstrated as a CVD chemistry base for depositing chromium-titanium-silicon (Cr-Ti-Si) coating on columbium with the processing equipment. Coating rate increases for the trideposition reaction was achieved with the following important process variables: gas feed geometry; reaction temperature; silicon chloride concentration; flow rate; dual chamber prereduction; titanium tetrachloride concentration; hydrogen concentration and argon dilution level of the hydrogen gas feed. Statistical analyses (i.e., T- and F-tests) confirmed the process variable influence for coating rate improvement at a 95% confidence level for coating 1/4-in. dia. round rod substrates of columbium with the developed CVD-barrel coating technology. Acceptable coating deposits were achieved on threaded substrates -- 1-in. threaded stud refractory fasteners of columbium alloy Cb 752 composition -- with the processing equipment. Other refractory fastener shapes including 1 1/2-in. long hex head bolts of Cb 752 were CVD coated at high reactor loading of ten substrates per run. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1969
- Accession Number
- AD0865504
Entities
People
- Carl L. Yaws
- Gene F. Wakefield
Organizations
- Texas Instruments