Structure and Properties of Antifriction Pseudo-Alloys of the Powder Steel–Copper Alloy, Infiltrated with Materials of Various Compositions

Abstract

The structure and properties of powder steel–copper alloy antifriction pseudo-alloys infiltrated with materials of various compositions are studied, it is shown that mechanical and tribological properties are determined both by the composition and structure of the steel skeleton and, to a large extent, by the composition and structure of the infiltrate. It has been established that the limiting content of lead in the infiltrate, which ensures the absence of lead deposits on the sample surface and a large (10–15%) residual porosity, should not exceed 3%. The use of a mixture of copper powders and alloying additives for infiltration is more technologically advanced than atomized bronze powders. It is shown that the wear resistance of pseudo-alloys with a chromium steel skeleton depends to a lesser extent on the composition of the infiltrate, since the main contribution to wear resistance is made by a hard steel skeleton. The introduction of 3–5% ultrafine aluminum oxide powders into the infiltrate leads to an increase in the seizure pressure by 1.2 MPa and wear resistance by 20–30% due to the refinement of the copper alloy structure and the deceleration of dislocations that arise during deformation due to friction. It is shown that during the wear of pseudo-alloys in the surface layer the structure is refined, martensite is formed in the skeleton, and, accordingly, the microhardness increases by 720–760 MPa.