Friction, wear, and airborne particle emissions from rail-wheel contact with laser cladded overlays - A pin-disc tribometer simulation

The present study uses a pin-on-disc tribometer to evaluate friction, wear, and airborne particle emissions for a rail-wheel contact. Test pins from UIC60 900A rail carbon steels were in contact with three types of test discs surfaces: R7 wheel carbon steel, laser cladding overlayed martensitic stainless steel, and laser cladding overlayed Ni-based-8% MnS self-lubricating alloy. Test results show about halving of the coefficient of friction, 0.42 to 0.22, and one ten-power lower specific pin and disc wear of discs with self-lubricating overlay compared to standard railway carbon steel contacts. Using stainless-steel overlayed discs also resulted in one ten-power lower specific disc wear, but pin wear is unchanged. Particle emission for the tests with discs with self-lubricating overlay is constant at almost 200 particles/cm3 while running in the distance is needed for the other tests. Almost all generated airborne wear particles were in the sub-100 nm range. The use of laser-cladded (LC) overlay reduced the number of airborne wear particles in the sub-100 nm range by more than a factor of 10.