Self-Lubricating Composites Enriched in the Surface with Molybdenum and Nickel

In powder metallurgy the addition of alloying elements is a widely used alternative to increase the service life of mechanical components. However, they have an associated cost. One less exploited process is surface enrichment (or surface alloying), whose same result is obtained on the surface, but at a much lower cost. Self-lubricating composites are especially complex to be enriched, precisely because they have to avoid the deposition of alloying elements over the lubricant stocks. This paper reports the characterization and tribological properties of self-lubricating composites enriched with molybdenum or nickel. Sintered samples were produced for comparative purposes. Wear resistance, friction coefficient and wear rate were analyzed for the evaluation of tribological properties. The results showed that the enrichment process did not cover the lubricant stocks. In addition, the Mo-enriched samples presented the best tribological results, with a 250 % increase in scuffing resistance in relation the sintered sample, and lower wear rate.