Chemical Vapor Deposition (CVD) Barrel Coating for Refractory Fasteners

Item

Title
Chemical Vapor Deposition (CVD) Barrel Coating for Refractory Fasteners
Date
1969
Index Abstract
Not Available
Photo Quality
Complete
Report Number
AFML TR 69-316
Creator
Wakefield, Gene F.
Yaws, Carl L.
Corporate Author
Texas Instruments, Incorporated
Laboratory
Air Force Materials Laboratory
Extent
266
Identifier
AD0865504
Access Rights
Export Controls
Distribution Classification
1
Contract
F33615-68-C-1433
DoD Project
474-8
DoD Task
None Given
DTIC Record Exists
No
Distribution Change Authority Correspondence
USAFSC LTR
Distribution Conflict
No
Abstract
Potential manufacturing-production equipment was established via CVD-barrel coating technology in this program for applying CVD coatings to large quantities of spall parts (i.e. refractory fasteners for aerospace structures). In Phase I, the practical equipment was designed, constructed, installed and tested in start-up. In these initial runs, trideposition reaction of hydrogen reduction of gas phase silicon, titanium and chromium chlorides was demonstrated as a CVD chemistry base for depositing chromium-titanium-silicon (Cr-Ti-Si) coating on small parts. In Phase II, optimization, production and evaluation studies were conducted with the designed equipment. Coating improvements including apparent optimum region and key process parameter effects were achieved with statistical runs and analyses (i.e., T- and F-tests at 95% confidence level). Process development was scaled-up to large quantities by uniform coating many small parts: (a) 1/4-in. dia. Round rods, 3 per run; (b) 1-in. threaded studs, 6-10 per run; ? 1 1/2-in. hex head bolts, 10 per run; (d) mixed shapes-bolts, studs, rods and flat panels, 20 per run; (e) refractory fasteners-bolts, studs and nuts, 30 per run; and (f) production demonstration-refractory fastener bolts and nuts, 30-50 per run. More than twenty demonstration runs at the incresed capability (i.e. coating 30-50 substrates per run) were conducted with reproducibility to illustrate that the CVD-barrel coating technology is within potential manufacturing production scope. Important coating properties (i.e. oxidation resistance for substrate protection, Cr-Ti-Si concentrations, mechanical strengths, etc.) were evaluated. For 2400 F oxidation environment, more than eighty and twenty hours of protection was achieved for round rod and refractory fastener small parts from production demonstration batches. Uncoated parts experienced severe failure in less than one-half hour. Cursory literature screening revealed favorable state-of-art comparison based on this program and two independent literature sources. In Phase III, gluoride and chloride routes were investigated for tungsten-tungsten silicide (W-WSi2) coating of tantalum. For the fluoride route, tungsten coating of tantalum T222 was demonstrated with uniform coverage of round rod small parts.
Report Availability
Full text available
Date Issued
1969-12
Provenance
Lockheed Martin Missiles & Fire Control
Type
report
Format
1 online resource
Media
AFMLTR69-316.pdf