| 摘要 |
An environmental resistant spot type coating is provided on a selected, discrete surface area of a high temperature operating article, by applying to the area a layer of at least one of the elements selected from Pt, Rh and Pd, and preferably Pt, to a thickness of about 0.0002" to less than 0.0006" and an average distribution of at least about 0.07 grams per square inch. The layer is heated at about 1800 - 2050{ F for about 1/2 - 4 hours to diffuse the element with the surface area. Then the layer is aluminided to provide an average total coating thickness of about 0.001 - 0.005". The article provided includes an environmental resistant additive coating diffused with the selected discrete area. The coating comprises an outer portion of at least about 17 wt. % of the selected element, and an aluminide of the surface area or substrate. In one form, the outer portion is a two phase outer portion: a first phase of an aluminide of the selected element at a content of at least about 40 wt. % interspersed with a second phase comprising an aluminide in which Al is at least about 20 wt. %. Between the outer portion and the surface area is an inner portion which is a diffusion zone comprising diffused selected element along with an aluminide and/or elements diffused from the surface area. |
