A heat-resistant coated member comprises a substrate composed of a material selected from among molybdenum, tantalum, tungsten, zirconium, aluminum, titanium, carbon, and alloys, oxide ceramics, non-oxide ceramics and carbide materials thereof, which is covered with a layer composed primarily of a rare earth-containing oxide. In addition to heat resistance, the coated member has good corrosion resistance and non-reactivity, making it highly suitable as a part for sintering or heat-treating metals and ceramics in a vacuum, an inert atmosphere or a reducing atmosphere.
This application is a Divisional of application Ser. No. 10/173,030, filed on Jun. 18, 2002 now U.S. Pat. No. 6,753,085, and for which priority is claimed under 35 U.S.C. .sctn. 120; and this application claims priority of Application Nos. 2001-183510 and 2001-354673 filed in Japan on Jun. 18, 2001 and Nov. 20, 2001, respectively, under 35 U.S.C. .sctn. 119; the entire contents of all are hereby incorporated by reference.
Priority Data
Jun 18, 2001 [JP] 2001-183510 Nov 20, 2001 [JP] 2001-354673
The present invention is a method for producing functionally graded materials that contain a hard phase that is embedded in a metal matrix phase. The material have a continuous gradient of a matrix metal phase. An example of these types of materials include functionally graded cemented tungsten carbide (the hard phase) that has a continuous gradient of cobalt (the matrix metal) from one reference position, for example, one surface of a part, to another reference position, for example, the opposite surface of the part or within the part. The functionally graded materials are sintered via a liquid phase sintering (LPS) technique. In order to achieve the desired continuous gradient of the matrix metal, an initial gradient of one of the chemical elements of the hard phase is designed and built into the part prior to liquid phase sintering. The exact gradient of the composition material elements that will be required depends on factors such as the desired final matrix metal gradient, the dimension of the part to be made, and the sintering time and temperature.
