Experimental Study On Electrochemical Grinding Of Cemented Carbide Coating Materials

Nuclear power is one of the most important clean energy, and most of the developed countries have used nuclear power as the main source of electricity, while China's nuclear power technology is in a stage of vigorous development. The friction pair of nuclear coolant pump is one of the key parts of nuclear power system, the requirements for its strength, hardness, wear resistance and corrosion resistance are very strict. Currently friction pair of nuclear coolant pump is mostly using the HOVF way. Coating the tungsten carbide cemented carbide materials on the substrate surface to improve its strength and hardness, achieve the effect of wear resistance and corrosion resistance. As the working environment of the friction pair of the nuclear coolant pump is severe, the residual stress of surface after processing is strictly required. If using the traditional processing technology, the efficiency is low and the tool wear is serious. At the same time, direct contact in the process will cause damage to the surface of friction pair which would affect the processing quality, and increase the residual stress.Because the high hardness, high wear resistance and other characteristics for tungsten carbide coating materials are difficult to processing, the electrochemical grinding is adopted in this paper. Electrochemical grinding is a kind of composite processing method which combines the mechanical processing and electrochemical processing:under the action of electrochemical a soft passivation film would be formed on the surface of the coating materials, and then the grinding wheel would scrape it off the surface. This method not only improves the contact pressure between the workpiece and the tool, but also improves the surface quality. Therefore, this paper launched a series of related research, and the specific content are as follows:This paper briefly introduces the general situation of thermal spraying technology and cemented carbide materials, and summarized the research status of the electrochemical grinding technology in China and abroad; from the viewpoint of electrochemical theory, describes the principle of electrolytic, analyzes its characteristics of processing and summarizes the effection of electrolyte, voltage, current density, and mechanical factors on electrochemical grinding; explains the definition of electrode and the phenomenon of polarization by researching the electrochemical properties of the material; tests the anodic polarization curve of the material by using the three electrode test system, analyzes effection of the component and concentration of the electrolyte, voltage and flow rate on the anode polarization curve, ultimately selected the suitable electrolyte; In order to explore the law of electrochemical grinding for cemented carbide coating materials, from the five aspects of voltage, duty cycle, tool feed rate, cutting depth and the speed of grinding wheel, optimizes the processing by using the single factor experiment method; analyzes and compares the characteristics between the electrochemical grinding process and the traditional grinding processing from three aspects of surface roughness, normal grinding force and surface residual stress.