Introduction of Nickel Coated Silicon Carbide Particles in Aluminum Metal Matrix Hardfaced by MIG/TIG Processes on Precoated Flux Layer

The aim of the study was to investigate an aluminium metal matrix surface layer hardfaced by shielded gas metal arc welding processes applying either metal inert gas (MIG) or tungsten inert gas (TIG), with standard wire filler onto the precoated flux layer – a baked resistant film containing electroless nickel coated micro/nano SiC particles. During baking, the components of the flux (MgCl2, NaCl, KCl and Na3AlF6) form a low melting eutectic, which: protects the hardfaced surface from oxidation, provides electrical conductance and keeps the particles on the surface during welding, as well as facilitates particles wettability and their interfacial bonding with the molten metal into the weld puddle. The hardfaced layers were studied by NDT, SEM and EDX, as well as nanoindentation and wear resistance tests. The results from the non-destructive radiographic test show lack of imperfections, porosity and slag inclusions only after TIG hardfaced using nano SiC particles. The wear resistance increased from 25 % (TIG) up to 71 % (MIG), which was due to the presence of the incorporated in the hardfaced layer reinforced phase of electroless nickel coated micro/nano SiC particles. The obtained wear resistance test results correspond to the obtained hardness test values.