Develop Sputter Deposited,Graded Metal-ZrO2Coating Technology for Application to Turbine Hot-Section Components.

摘要

The deposition of ceramic coatings on gas turbine hot section components by high-rate sputtering was investigated. Stabilized zirconia was the primary ceramic used, however some work was done with magnesium zirconate. The main thrust of the program was the development of methods to improve coating adherence by accommodation of the strain due to the expansivity difference between zirconia and the superalloy components. The use of a graded composition interlayer was the only method which proved useful; its utility was found to depend on the ductility of the metallic constituent and the details of the composition gradient. When the coatings were evaluated by rapid thermal cycling between 25 and 950 C, graded composition layers up to 0.1 mm thick survived six complete cycles. Pure zirconia overlayers were less adherent. A second area of investigation involved the stoichiometry of the zirconia deposits, which exhibited oxygen deficiencies dependent on deposition rate and substrate temperature. The deficiencies were reduced by oxygen additions to the sputtering atmosphere, but it was necessary to simultaneously reduce the deposition rate and substrate temperature to reach approximate stoichiometry. (Author)