Tribological Performance Enhancement of Bronze Alloy through Microwave Irradiation: Fundamental Tribo-Tests and Real-Time Journal Bearing Applications

In the present work, the microwave hybrid heat (MHH) treatment process was employed to enhance the mechanical and tribological properties such as hardness, friction and wear resistance of bronze alloy (C93200) specimens. In the first phase of the experimental investigation, cylindrical pin specimens were subjected to MHH treatment for 5, 10 and 15 min at 600 ± 20 °C and allowed to cool by using air cooling and oil quenching methods. The grain size refinement, reduction in porosity and formation of intermetallic compounds were noticed in the MHH-treated specimens which significantly improved in hardness. The pin specimen which was exposed to MHH treatment for 15 min followed by air cooling showed a 62.9% enhancement in hardness. The microstructural and crystallographic surface changes that occurred in the bronze pin specimens due to MW treatment were characterized by using SEM/EDS, optical microscopic and XRD analysis techniques. Further, the friction and wear performance of MHH-treated pin specimens were evaluated by using a pin-on-disk tribometer, and the results were compared against the untreated specimens. In the second phase, the bearing bush was exposed to the MHH treatment process for 15 min followed by air cooling. This bearing was subjected to fatigue load cycles on a journal bearing system over a period of 1200 h at 200 N load and 800 rpm. The specific film thickness, friction coefficient, wear coefficient, maximum film pressure and power loss parameters were evaluated to assess the performance of MHH-treated bearing. The results showed a 51.3 and 39.1% reduction in friction and wear coefficient values, respectively, in the MHH-treated bearing than that of untreated bearing subjected to fatigue tests under the same operating conditions.