Abstract: Sintered metal articles especially sealing rings of less than 25 mm diameter are formed by plating sintered metal skeletons with a metal of lower melting point than the metal of the skeletons, for example, copper. The plated skeletons are then heated, preferably in a stack, to melt the plated metal, which infiltrates the skeletons. The articles so produced are stronger than and have greater elasticity than the skeletons themselves due to the presence of the plated metal in the skeletons.

Abstract: The invention consists of a process for the production of articles by powder metallurgy including the step of adding powdered mica to the metal powder before compacting and sintering. It also extends to a sintered metal product containing mica, in particular a valve seat insert and a shock absorber piston ring. The quantity of mica is preferably between 0.5% and 2% by weight of the metal.

Abstract: A sintered metal article such as a piston ring or a sealing ring (in particular those having a cross-section area not exceeding 20 mm.sup.2) having a density which is at least 88.5% of the theoretical density, having a fine machined surface finish, and having a nitrocarburized surface layer which is not found at a depth of more than about 250 microns from the surface.The invention also includes the process of manufacturing such an article.

Abstract: A process for the manufacture of sintered metal articles includes the steps of selecting a prealloy powder having a composition consisting essentially of 10-18% chromium, 2-6% iron, 2-6% silicon, 2-6% boron, 0.5-2% carbon, balance nickel, mixing the prealloy powder with copper powder in an amount equal to between 20% and 50% of the weight of the total of prealloy powder and copper, preferably adding a small percentage of a suitable lubricant, pressing the mixture to form a compact, and sintering the compact in the range 1050.degree.-1100.degree. C. for such a time that the copper and the nickel-rich prealloy only partly dissolve in one another.

Abstract: A metal article is formed by a sintered body of an austenitic ferrous alloy containing chromium and nickel, the ferrous alloy having been infiltrated with a copper or copper base alloy during or after sintering of the body.When a body of aluminum or aluminum alloy is cast around the metal article, a good bond therebetween is achieved. The metal article can thus provide a wear-resistant insert, for example a piston ring carrier in an aluminum piston or a valve seat in an aluminum cylinder head for an automobile.