Abstract:
Laser cladding is a surface variation method in which a laser beam via optical components is used to melt an additive material (a functional or corrosion-resistant alloy) and integrate it onto a substrate by the formation of a thin dilution bonding layer. In this process, a relatively thick layer of the continuous fed powdered material maintains its initial solid properties and only a thin layer is marginally alloyed to the substrate for adherence purposes. Thus, the process must be separated from that of laser surface alloying as it is tougher than coatings created by thermal plating, and harmless to health, too. The morphology of the clad and its performance depends on the characteristics of the melt pool and the additive material injection technique. The process can be carried out consuming wire/powder filler material and that too laterally or coaxially. Powder based injection are becoming more pertinent because powder material offers a much lower attenuation and also same injected coaxially to laser beam results into multi-directional deposition of material via co-axial nozzles.
The continuous coaxial nozzles are complex and difficult to install because two conical parts are coaxially assembled and then perfectly align them with the laser beam. Two different materials are used in the fabrication of this cladding head. High thermal conductive metal is used on parts located near the depositional zone and variant of stainless steel is used on parts with complicate geometries which are difficult to cut. Despite of high cost, these nozzles are preferred due to the capability of precise deposition. However, in general there are open ended solutions for Laser Cladding processes industrially, particularly modelling and designing of co-axial nozzle following fabrication have been carried out in this study. Yet, the design of nozzle is novel idea and more advances in this topic are expected.
