Research On The Ni Based Alloy Cladding On Al Surface By Laser And Its Tribological Characteristics

In this paper, the technology and theory of the laser cladding on the surface of aluminum alloy has been revealed in detail as follows:1. The melting process and solidify of the powder of the cladding layer on the surface of the aluminum alloy have been analysed, the area of the cross section of the cladding layer and it's diluent rate have also been formulated. To determine the laser power accurately, the absorptance of the aluminum surface to the laser energy must be given and the measure methods has been disused in detail.2. The laser parameters have been set through the cladding experiment on the aluminum surface, the ordinary principle to the set of the laser parameter has been supplied as: the input energy of the laser and the thickness of the cladding layer must be right, under this principle, the laser energy density, the laser scanning velocity , the diameter of the powder and the pre-put powder thickness on the aluminum surface are the key points for the cladding layer.3. It has compared the difference of the cladding layers formed under different laser energy, scanning velocity and different diameter of the powder , the pre-put powder thickness, ingredient of the powder. It has conformed the law on the influence factors to the microstructure size and the diluent of the base material to the cladding layer by the experimental results.4. Under the direction of the alloy design theory, several Ni based powder ingredient for laser cladding to the aluminum surface are given. Through the study by micro-hardness test on the cross section of the cladding layer, microstructure, SEM for the surface shape of the cladding layer, XRD for the element content on the different part of the cross section of the cladding layer, the analysis result shows that the cladding layer with one element Ni has combined properties, the cladding layer with WC powder besides Ni powder has properties with high hardness and good friction characteristic, La₂O₃ in the ingredient helps to lessen the size of the microstructure of the cladding layer.5. The solution method to the over melt and under-melt of the aluminum surface during the several overlapping cladding process is supplied as to change the laser scanning parameters during the cladding process.6. The friction characteristics of the cladding layer are achieved by the pin-plate dry friction machine, the mechanism of the friction is analysed through the diagram of the friction data noted by computer, and the SEM shape, XRD helps to give the result of the cladding layer with different powder ingredient.7. The laser cladding to the aluminum piston ring groove is one of the main utilizations of the research work of this paper, for the success to obtain a long life time piston, a high quality cladding layer is necessary. It gives the machine design to the piston laser cladding, and the special technology is discussed in detail.