Formation of Ni-base Self-fusing Layers with Using Direct Diode Laser

Abstract

Laser cladding is an economic process to produce protective layers against wear and corrosion on highly loaded components. Advantages of laser cladding are uses of high melting point materials, low heat influence and heat distortion to a substrate, and high adhesion strength of a cladding layer. Laser cladding is expected as a surface modification technology to apply against the materials which are required in severe environments. The Ni-base self-fluxing alloy thermal sprayed coatings are widely employed to improve the quality of components whose surface is submitted to wear and corrosion. The use of thermal spray coatings for the wear protection of bulk materials is used throughout industry for mechanical components such as engine parts, hydraulic turbines and bearing surfaces . For the past few years, the authors have been developing a laser cladding method employing a high energy density laser beam heat source . Utilizing this method, steel plate was coated with Fe-B alloy powder to produce a hard surfacing layer with high hardness and erosion resistance. To develop a more effective cladding process, laser cladding was investigated using a powder feeder and Ni base self-fluxing alloy powder. The deposition efficiency and the thermal efficiency in dependence on the processing speed are determined. With minimal overall heat input, functional layers with thickness of millimeters are obtained and the surface processed per time unit is increased. Powder feed rate and track offset have to be adjusted simultaneously in order to obtain a sufficient cladding quality. The laser cladding layers were examined by optical microscope, scanning electron microscope and electron probe micro analyzer. The properties of the cladding layer were examined using the Vickers hardness test and sand erosion test.