Design Of Ion Plating Machine Vacuum Unit And Study On The Coating Process

The cutting tool is often coated with a film to improve its wear resistance, corrosionresistance and the life of it. Preperation of thin film by ion plating system is an importantmethod which is widely used in cutting tool industry. The ion plating system is usually carriedout under high vacuum environment. Therefore, the high vacuum environment is particularlyimportant for the ion plating machine.Firstly, this paper introduced the basic knowledge of vacuum technology, as well as thestructure and principles of several commonly used vacuum equipments. Comparing theadvantages and disadvantages of various vacuum pumps and combining with therequirements of vacuum environment,overall design scheme of the vacuum system wascarried out. By calculating the flow guide and pumping speed, the diffusion pump was used asmain pump, and the vacuum unit of root pump and mechanical pump was used as thepre-pump in the high vacuum unit. The actual tests were performed.The result of these testsproved the feasibility of the design.The TiAlN film was prepared successfully in ion plating machine. This paper studied theeffects of the Al target current on the properties of films. The hardness, adhesion, surfacemorphology, phase and fracture morphology were investigated by microhardness tester,scratch tester, metallographic microscope, X-ray diffraction, SEM and EDS, respectively. Theresult showed that the color of the coating prepared by the different Al target currents showeddifferent colors. The color changed from yellow-red to black with the increasing of Al targetcurrent. The micro-hardness and adhesion strength of the coating reached a maximum of2893HV and75N, respecticely. Metallographic observation showed that the surface of film isgenerally flat, but there were pits of varying sizes. With the increasing of Al target current,film surface became more smooth. When Al target current reaching20A, the surfaceroughness increased. X-ray diffraction showed that Al target current smaller,just TiN phase,when Al target current up to18A appeared Ti3AlN phase, indicating that the enegy depositionof Al atoms on the surface of the substrate was determined by the size of the Al target current.The energy of Al atoms only above a certain threshold value, the Ti atoms in the TiN could bereplaced. The columnar crystals of coating growth could be seen by scanning electronmicroscopy. EDS analysis indicated that Al content in the film with increasing Al targetcurrent increased.