Process for Obtaining Tight Components by Powder Metallurgy

摘要

The process: includes mixing a metallic powder including iron or nickel or copper or mixtures of two or three elements thereof where the sum thereof defines at least 55% in mass of the metal matrix of the component to be produced, and a molybdenum disulfide powder as a densification agent and as a solid lubricant with a content from 3 to 30% in volume; filling a mold with the mixture and obtaining a compact presenting from 5 to 25% in volume of primary pores; and subjecting the compact to a temperature and time sufficient to allow the reaction of the molybdenum disulfide with the matrix, forming iron sulfide, nickel sulfide or copper sulfide, and the diffusion of the molybdenum in the matrix; and subjecting the compact to temperature sufficient to transform the sulfide into a liquid phase, filling the primary pores before finishing the sintering step of the compact.

主权项

1. A process for obtaining tight components by powder metallurgy, characterized in that it comprises the steps of:
i) mixing a metallic powder selected from any of the elements defined by iron, nickel, copper and mixtures of two or three of these elements, as long as the content of the element or mixture thereof defines at least 55% of the mass of the metal matrix of the component, and a molybdenum disulfide powder as a densification agent and as a solid lubricant with a content varying between 3 and 30% in volume; ii) homogenizing the mixture obtained in the previous step; iii) filling the cavity of a mold, by compaction of the homogenized mixture, until achieving a compact resistant to handling and presenting between 5 to 25% in volume of primary pores; iv) subjecting the compact to a temperature and period of time sufficient to allow the reaction of the molybdenum disulfide with the metallic powder which forms the matrix of the component to be produced, forming at least one of iron sulfide, nickel sulfide and copper sulfide, and the diffusion of the molybdenum left from the reaction in the metallic powder which forms the matrix; v) subjecting the compact, with the already reacted molybdenum disulfide, to a temperature sufficient to transform the sulfide into a liquid phase filling the primary pores before finishing the sintering step of the compact.