OXIDATION RESISTANT COATED NIOBIUM-BASE ALLOY AND ITS MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To solve the following problem: a niobium-base alloy is expected as a material used under a high temperature to improve the thermal efficiency of an aircraft engine or thermal power generation because of its melting point approximately 1,000°C higher than that of a nickel-base alloy, but the alloy is insufficient in oxidation resistance and a conventional oxidation resistant coating hardly prevents its deterioration due to interdiffusion between the alloy and the coating layer.;SOLUTION: An aluminum foil is laid on a base-material of niobium-base alloy, and a powder of a chemical compound, which forms an alumina protective coating film at a high temperature an has a linear expansion coefficient of 6-10 ppm/K, is further laid on the aluminum foil. The above overlapped materials are subjected to press sintering under a pressure of 20-80 MPa in the atmosphere of vacuum or argon gas and the aluminum foil under sintering absorbs a trace amount of oxygen in its periphery to form an alumina layer. Thereby, the oxidation resistant coated niobium- alloy having a double layer structure, where the alumina layer is interposed between the niobium-base alloy base-material and an outside coating layer forming the alumina protective coating at a high temperature and exhibiting an excellent oxidation resistance, is obtained.;COPYRIGHT: (C)2003,JPO