Development of Ni + TiB2 metal matrix composite coating on AA6061 aluminium alloy substrate by gas tungsten arc cladding process

Abstract

In the present research work Ni + TiB2 metal matrix composite coating was deposited on AA6061 aluminium alloy substrate using nickel and titanium diboride as precursor by gas tungsten arc cladding process. The TIG torch was used as heat source to melt the preplaced powder mixture. The mixture of TiB2 and Ni powders were taken as 10 wt% and 90 wt% respectively. The three level of currents were used as variable parameters to melt the pre-placed powder layer viz. 120Amp, 140Amp and 150Amp. The microstructure of coated layer was investigated by field emission scanning electron microscope (FESEM) and the chemical composition of the coated layer was detected by energy dispersive spectroscopy (EDS). From the microstructural study it was found that the coating exhibits good metallurgical bond between coated layer and substrate. For analyzing the micro-hardness of coated layer Vickers micro hardness testing was performed along the cross-section of the coated samples. The maximum microhardness value of coated layer was 1233 HV, for sample cladded at current of 150 Amp. It was observed that increase in micro hardness value of coated sample was about 11 times higher than that of the aluminium alloy substrate (110HV). It was found that with increase in applied current, amount of microhardness of coated sample increased.