THE ELABORATION AND CHARACTERIZATION OF SOME CuTi FRICTION MATERIALS

Friction materials based on copper alloys are extensively used for high performance clutches and brakes. Copper –titanium powder system is a very interesting combination of friction materials, because of its high sintering activity and its good tribological behaviour. Several compositions were tested; the maximum concentration of titanium was 35%, with increments of 5%. Samples were compacted at 400 MPa and sintered in low vacuum (4·10 Pa) at 850°C. They were studied by optical microscopy to observe structural transformations. The diffusion of copper provided formation of pores in the samples. The most affected samples were those containing 15% Ti. Increase in titanium content led to a decrease of compression strength and impact resistance. The hardness values varied as a function of the place where measurements were made; high values were in transitions areas and the lowest in the centres of the samples.