Researches Of Hf?B,C?-Al₂O₃/Cu Composite Coating Prepared By Laser Cladding

Copper and its alloys have excellent electrical conductivity and thermal conductivity,and are widely used in many fields.However,with the breakthrough development of new industrialization with Chinese characteristics,the service performance of materials is becoming more and more demanding.This restricts the deep application of copper,so there are still many problems to be solved.On one hand,the low hardness and poor wear resistance of copper have become the key problems restricting its development.On the other hand,the binding degree between copper and other reinforcing phases is one of the reasons that restrict the application of copper based composite coatings.The combination of laser cladding technology and in-situ reaction technology has injected new vitality into the preparation and development of composite coatings.The in-situ synthesized reinforcing phase is well bonded to the matrix interface.In this paper,firstly,composite coatings of Hf?B,C?-Al₂O₃/Cu was prepared by laser cladding technique and in-situ reaction technology.The effect of laser cladding parameters on the preparation of composite coatings was studied.Secondly,different contents of the microstructure and structure,physical properties,mechanical properties and tribological properties of relative composite coatings were discussed.Thirdly,the effects of the interface of the composite coatings were studied.The main results are as follows:1.Based on the evaluation of laser process parameters,the optimized laser process parameters are determined as power 2000W,such as the macroscopic morphology,the dilution rate and the interface between pure copper substrate and composite coating of composite coatings of Hf?B,C?-Al₂O₃/Cu.2.The microstructure of composite coatings of Hf?B,C?-Al₂O₃/Cu was studied.The results show that the main composition of the composite coating are HfB₂,HfC,Al₂O₃,?Cu,Ni?and so on,which is consistent with the in-situ reaction results designed according to the phase diagram.The interface between the reinforced phase and matrix was analyzed by Transmission Electron Microscope,and the results showed that the interface between the reinforced phase and the matrix was clean and showed good metallurgical bonding.3.The properties of Hf?B,C?-Al₂O₃/Cu composite coatings with different contents were studied.It was found that the hardness and tensile strength of the composite coatings increased with the increase of the proportion of reinforcement phase,indicating that the reinforcing phase did strengthen the copper substrate.The main reinforcement mechanism is load transfer enhancement.But its relative density decreased,which indicated that the excess ratio of reinforcement phase would affect the interfacial bonding with Cu matrix,thus affecting other properties.4.The tribological properties of Hf?B,C?-Al₂O₃/Cu composite coatings with different contents were studied at room temperature.The wear rate of the composite coating was low and it had excellent wear resistance.The results showed that the wear resistance of the composite coatings was improved when the proportion of reinforcement phase was increased.At the same time,the tribological properties of the composite coatings under different loads,sliding velocities and with or without current were studied.The loading increased,the wear rate of the composite coating showed a tendency of continuous improvement,and the friction coefficient showed a valley-like change.As the sliding speed increased,the friction coefficient and wear rate of the composite coating increased.As the current increased,the wear rate of the composite coating increased.