Investigation of Wear Behavior of PET Bushings for Turbine Components

In this study, for the first time, a new generation PET (Polyethylene terephthalate) material bushing design and prototype production by machining was carried out for the turbine blade and adjustment cap blade used in turbine systems within the Arnes Mechanical Machinery Design Center. Within the scope of the study, the tribological properties of the PET material used as the bushing raw material were investigated under different sliding speeds, loads, and sliding distances. Abrasive wear tests were applied using the pin-on-disc method at 3 and 4.5 m/s sliding speeds, 100-, 200-, and 300-meters sliding distances, and 5, 10, 15, and 40 N loads. The wear performance of the PET material was evaluated through the parameters of volume loss, coefficient of friction, and surface roughness. The results obtained showed that the applied load and sliding speed had a significant effect on the wear behavior of the material. The increase in load caused a significant increase in volume loss by creating a higher contact pressure on the material. This situation showed that higher loads create more contact pressure on the surface, causing deformation and material loss in the material's microstructure. It was evaluated that plastic deformation and abrasive wear mechanisms are dominant on the material surface under high loads. In contrast, increasing the sliding speed caused a decrease in the coefficient of friction and surface roughness. It was observed that at higher speeds, the thermal effects caused by friction on the material's surface resulted in the formation of a tribofilm, thus increasing the surface protection capacity of the material and decreasing the coefficient of friction and surface roughness. The findings showed that the bushings manufactured from PET material can be successfully used as an alternative to metal alloy bushings under difficult service conditions in turbine systems.