| 摘要 |
A sintered metal article containing ducts, holes or voids is produced by compacting metal powder around shaped formers which consist of a core of non ductile high melting point material such as stainless steel and a coating of a volatilisable metal such as cadmium, zinc or indium, preheating the compact at a temperature high enough to volatilise the coating metal, removing the metal cores and finally sintering the compact. The thickness of the metal coating should be less than 20% of the diameter of the core and the formers should be so positioned in the compact that at least one end of each former is exposed at a face of the compact during the preheating. In a specific example a mixture of metal powders to form an alloy of 20% Cr, 16% Co, 2,35% Ti, 1,35% Al, 0,07%-0,1% C, 0,05% B and the balance Ni, is pressed around formers of stainless steel 0,061 inch diameter coated with a layer of cadmium 0,005 inch thick at 35 tons per square inch in a floating die assembly. The cadmium is removed by heating at 650 DEG C. in vacuum and after cooling the steel formers are removed. The compact is finally sintered in hydrogen or vacuum at 1300 DEG C. to 1325 DEG C. for 20 hours. Specification 611,466 is referred to.ALSO:A sintered metal article containing ducts, holes or voids is produced by compacting metal powder around shaped formers which consist of a core of non-ductile high melting point material such as stainless steel and a coating of a volatilisable metal such as cadmium, zinc or indium, preheating the compact at a temperature high enough to volatilise the coating metal, removing the metal cores and finally sintering the compact. The thickness of the metal coating should be less than 20% of the diameter of the core and the formers should be so positioned in the compact that at least one end of each former is exposed at a face of the compact during the preheating. In a specific example a mixture of metal powders is pressed around formers of stainless steel 0,061 inch diameter coated with a layer of cadmium 0,005 inch thick at 35 tons per square inch in a floating die assembly. The cadmium is removed by heating at 650 DEG C in vacuum and after cooling the steel formers are removed. Specification 611,466 is referred to. |
