Publication

Abstract : Combining two dissimilar materials can provide exceptional metallurgical characteristics that offer the potential for ideal operational performance in the gears in the transmission sector. This work investigates the influence of Cu/Ni electroplating (cast iron surface) on the mechanical properties of the cast iron (CI)/phosphor bronze (PB2) bimetal gears produced by inserting the CI into the molten bronze. Results demonstrate that coating significantly impacted the interfacial microstructures and mechanical properties of CI/PB2 bimetal. In the uncoated specimen, the bonding interface consists of gaps and voids, leading to poor bonding. In the case of Cu-coating on CI, the integrity of the joint is significantly increased by the adhesion of molten PB2 to the CI. However, the SEM/EDS analysis reveals phosphorous (P) diffusion toward the CI interface. While in the Ni-coated CI, a sound metallurgical bonding with the reaction layer is observed. The compressive shear strength of CI/PB2 with Ni coating reached a maximum value of 48 MPa, Cu-coating 40 MPa, and the uncoated sample 16 MPa. The fracture morphology of the uncoated specimen shows the existence of oxides, unbonded regions, and cracks developed in the voids between the materials. In both Ni- and Cu-coated specimens, fracture mainly occurs on the PB2 side, with brittle Fe-P phases and ductile fracture of PB2. In uncoated specimen, phases on the fracture surfaces reveal the presence of graphite and iron oxides, which are likely responsible for the flat and brittle fracture. Fe3P and Fe2NiP phases are detected on the fracture surfaces indicating the metallurgical bond between CI and PB2 in Ni-coated sample.