Effect of stand-off-distance on the performance of TIG cladded TiC-Co coating deposited on Ti-6Al-4V alloy

Abstract

TiC-Co layer was fabricated on Ti-6Al-4V alloy plate by TIG cladding route using TiC/Co powder blend of equal weight ratio. The distance between the electrode and the work, namely stand-off-distance (SOD), was varied between 4 and 6 mm during the TIG arc scanning, which altered the arc volume and subsequent heat intensity in the powder melt pool. A significant variation in the clad track width and depth was noticed due to the discrepancy in the arc-workpiece interaction area for increasing the SOD. Although almost uniform thickness in the clad layer was obtained, owing to discrepancies in the specific density and thermal conductivity between TiC, Co powder, and Ti-6Al-4V substrate, the constituents of the clad layer were found in-homogenously distributed. Consequently, a marginal diversity in the micro-hardness and wear resistance of the clad layer was recorded for the alteration of SOD conditions. Variation in the concentration of partially melted spherical shaped TiC particles, resolidified dendritic TiC, and other intermediate phases alter the microhardness value in different regions of the clad layer. The results indicated that the wear value or height reduction of the clad specimen was up to 15 times lower than the substrate material when tested against hardened steel. In contrast, the wear value was reduced almost three times when tested against the alumina abrasive disc under different load conditions.