Abrasive Wear Behavior of a Si3N4-MoSi2 Composite

MoSi₂ particles (20 vol%) have been added to Si₃N₄ to form ceramic matrix-intermetallic composites. Benefits associated with the addition of the MoSi₂ to Si₃N₄ include higher strength, higher fracture toughness, no loss in oxidation resistance, and lower electrical resistivity. However, because the hardness of MoSi₂ is approximately half that of Si₃N₄, a decrease in the specific wear rate of the Si₃N₄-20 vol% MoSi₂ composite is expected to result from the incorporation of the MoSi₂ into the Si₃N₄. In this U.S. Bureau of Mines and Los Alamos National Laboratory study, it is found, however, that the specific wear rate of the composite during two-body abrasion by SiC particles is equivalent in magnitude to the specific wear rate of monolithic Si₃N₄. The specific wear rates of both the Si₃N₄-20 vol% MoSi₂composites and monolithic Si₃N₄ are four to five times less than that of monolithic MoSi₂.