PURPOSE: To perform the formation of a Cr-B-Al coating film excellent in corrosion resistance and thermal shock resistance, by coating the surface of an Ni- base alloy with Cr while forming an Al-coating layer to the Cr-layer by utilizing a pack agent before applying heating diffusion treatment.
CONSTITUTION: A Cr-coating layer is formed to the surface of an Ni-base alloy and, subsequently, the coated alloy is embedded in a pack agent consisting of, on a wt. basis, 15W30% of an Al-powder, 1W3% of a halogenation promotor such as NH4Cl, 0.1W3% of a B-powder and the remainder of an Al-powder and heated to about 700W800°C in an inert gaseous atmosphere to diffuse and penetrate Al-B through the surface thereof to form an Al-coating layer. In addition, the formed alloy layer based on Ni2Al3 is subjected to diffusion treatment under heating to be converted to an alloy layer based on Al-rich NiAl. By this method, Cr-B-Al coating having excellent corrosion resistance and thermal shock resistance can be applied to an Ni-base heat resistant alloy.
OOTAKA KIYOSHI
OKAYAMA AKIRA
WATANABE HIROSHI
| JPS56112459A | 1981-09-04 |