COMPOSITE CYLINDER

PURPOSE:To load a compressive stress on the sintered alloy layer of an inner surface to improve resistances to abrasion and cracking, by a method wherein recesses and projections are formed on jointing boundaries between a cylindrical body and the sintered alloy layer to joint them while the amounts of shrinkage of the cylindrical body and the sintered allow layer from 800 deg.C to a normal temperature are specified. CONSTITUTION:The material of a metallic cylindrical body 1 is selected so as to have a linear expansion coefficient larger than the same of a sintered alloy 2 while recesses and projections 3 are formed on the jointing boundary between both of the cylindrical body and a sintered alloy layer to joint and integrate them, therefore, a compressive stress is applied on the sintered alloy layer. Both ends of the alloy layer 2 are embedded into the cylindrical body 1 in a condition that they are enveloped by the cylindrical body, therefore, the compressive stress of the alloy layer 2 is enhanced. The temperature of the starting point of shrinkage is 800 deg.C. Under a temperature exceeding 800 deg.C, both of the metallic cylindrical body and the sintered alloy layer are soft and cause plastic deformation easily, therefore, remaining stress will never be generated between both of them. The amount of shrinkage of the sintered alloy layer deltaA is made smaller than the amount of shrinkage deltaB of the metallic cylindrical body in order to provide the sintered alloy layer with a compressive stress.