Hardfacing of composite layer on aluminum by GTAW process

Gas Tungsten Arc Welding (GTAW) was applied to create a composite layer on the surface of cast aluminum alloy A380. Different mixtures of aluminum, silicon and silicon carbide powders with Sodium silicate solution were pasted on the substrate. After drying and preheating, surface melting was conducted by TIG process. A composite layer of Al-SiC was created on the surface by this process. Evaluation of microstructure and properties of obtained composite clad was done by X-ray diffraction (XRD), optical and scanning electron microscope (SEM), elemental microanalysis (EDS) and microhardness testing methods. The results showed uniform distribution of SiC particles in Aluminum dendritic matrix. SiC particles are dissolved partially during heating and melting of the preplaced layer and may lead to the formation of Si and Al4SiC4 phases with a Vickers hardness of about 1000 HV. Surface hardness can be increased by further addition of silicon in preplaced powders.