Development of Practical Techniques for Applying Protective Coatings to Columbium Alloys

摘要

Three coating processes--fused salt bath, fluidized bed, and slurry dip application--were investigated to develop practical and reliable techniques for applying oxidation protection coatings to columbium alloys. The substrate used was D-14(Cb-5Zr). Only coatings of known composition were applied. Titanium, chromium, and silicide coatings were deposited by the fused salt bath process; silicide coatings by the fluidized bed; and tin and aluminum coatings by slurry application. Early in the program, the work on slurries was expanded to include a study of their electrokinetic behavior. The several process variables pertinent to each technique were evaluated to determine the range of operating conditions that can be used to produce the desired coating. All coatings were tested for oxidation resistance at 2500 to 3000F. Further evaluation included metallographic examination of the coated samples. The program resulted in the development of several suitable coatings. Work is being continued to demonstrate further the feasibility of these coating techniques. (Author)