Microstructural analysis of sintered iron parts joined by sinterbonding
摘要
Components produced by powder metallurgy are inherently porous, making traditional joining methods challenging. This research investigates the joining of iron-based powder metallurgy components using iron powders through sinterbonding. This solid-state process overcomes the limitations of conventional methods and has broad applicability for increasing the size of powder metallurgy components. The joining of green and sintered Fe compact samples was evaluated, as well as variations in the amount and composition of the bonding agent. Cylindrical Fe substrates were produced by uniaxial cold pressing, and Fe and Fe15%Ni metal powder suspensions were used as bonding agents. The substrates were joined by sintering at 1393 K for 2 h in a 95%Ar/5%H2 atmosphere, and the resulting microstructure was examined using optical microscopy, scanning electron microscopy, and Vickers microhardness testing. Joints where the bonding agent was applied before sintering presented the best microstructural continuity. Nickel powder in the bonding agent reduced the bonding layer’s porosity from 37 to 16% due to composition gradients and the Kirkendall effect. Additionally, adding Ni increased joint hardness from 48 to 153 HV. The results indicate that the addition of Ni enhances the bonding process between iron-based powder metallurgy parts and demonstrate that sinterbonding can address technological challenges in joining sintered parts.