Abstract:
The study is aimed at using laser cladding
technique to deposit a thick coating of composite TiZnNi on
titanium alloy Ti-6Al-4V substrate. The composite powder
was mixed with Zinc (Zn), Nickel (Ni) and Titanium (Ti), in
which the tubular mixer was used to prepare the mixture. The
laser metal deposition technique that was employed in the
process was used to control the heat input, which governed the
resulting microstructure of the ZnNiTi coating that was
produced. This was based on the analysis that was conducted.
The results of the hardness obtained from the Vickers microindenter revealed that there was an improvement as the
hardness measured for the cladded ZnNiTi layer was
approximately 1396.90 HV0.1 and the hardness of the Ti-6Al4V substrate was measured to be 320.8 HV0.1. This
improvement was attributed to the NiTi, Ni3Ti, hard Ni4Ti3
and intermetallic phases that formed, this was confirmed by
the analysis done on the cladded layer by employing EDS and
XRD. The grain form and structure as well as the mechanical
properties of the cladded layer were significantly affected by
the heat input from the laser beam. At higher scanning speed
of 1.0 m/min, the coating and substrate being limitedly mixed,
resulted in the cladded layer having a significantly higher
hardness than the substrate, but some hardness values
gradually reduced after the cladded layer towards the
interface and heat affected zone. The behaviour of the coating
hardness property was improved by 4.4 compared to the
hardness of the uncoated titanium substrate. The
characteristics of the hardness of the deposited coating was
heavily affected by processing parameters, which the grain
morphologies and concentration of phase composition formed
were predominant in the result of the hardness properties.
Industries of biomedical and mechanical components may
implement the application of composite ZnNiTi coating since there was an improvement on the hardness characteristics,
which is usually of major concern in industrial applications.
