Plasma Enhanced Magnetron Sputtering Nitriding And Chromium Nitride Coating Preparation

In this paper,plasma enhanced balanced magnetron sputtering technique is used to study the nitriding layer thickness,micro-structure and mechanical properties of high speed steel surface by controlling nitrogen flow rate,substrate bias pressure and nitriding time.Chromium nitride coating was prepared on the surface of stainless steel by plasma enhanced balanced magnetron sputtering technique.Influence on deposition rate,micro-structure and mechanical properties of the coating were studied by controlling nitrogen flow rate.Plasma enhanced balanced magnetron sputtering technique and arc ion plating technique are used to make TiN and CrN coating on C21,12CrMoV and H13 shear blades respectively.Different microstructures and mechanical properties among the coatings of different parameters and matrixes.The experimental of nitriding results show that with the increase of nitrogen flow rate from 100sccm to 200sccm,the surface of high speed steel after nitriding precipitates in the form ofγ-nitride phase of Fe₄N.The average friction coefficient of nitriding layer is reduced from 0.64 to 0.47,which is smaller than the average friction coefficient of matrix,and the wear depth is decreased.With the increase of substrate bias from 100V to 250V,the average friction coefficient of nitriding layer decreases from 0.62 to 0.38,and the wear depth decreases.Nitrogen atoms preferentially diffused at grain boundaries and sub-crystalline boundaries in the matrix.With the increase of nitriding time from 1 h to 4 h,nitride must follow grain boundaries.After nitriding,the surface of high speed steel precipitated in the form ofγnitride phase of Fe₄N,the nitriding time was prolonged,the amount ofγnitride precipitation of Fe₄N increased and the wear depth decreased.The experimental of CrN coating on stainless steel results show that the chromium nitride coating has columnar crystal growth pattern.With the increase of nitrogen flow rate from 75sccm to 120sccm,the thickness of the coating will not be affected,the growth density of chromium nitride coating will increase and the surface roughness of the coating will increase.In the process of coating growth,CrN and Cr₂N are accompanied,and Cr₂N is transformed to CrN.When the nitrogen flow rate is 90sccm,the maximum adhesion is 80 N,the average friction coefficient of the coating is 0.65 and the average friction coefficient of the coating is less than the average friction coefficient of the substrate of 0.8,and the wear depth decreases.The results of the coating on the shear blades show that obviously change of microstructures were happened on the matrixes of C21 and H13 shear blades before or after coating.Carbides were formed within the matrixes.However,no obviously change of microstructures were happened on the matrixes of 12CrMoV shear blade before or after coating.There is no influence on the properties of 12CrMoV shear blade during coating.The nano hardness of the TiN coating on C21 shear blade is 30GPa.The hardness and modulus of TiN coating on 12CrMoV and H13 are both lower than the coating that make by arc ion plating.The thickness and binding force of TiN coating on 12CrMoV and H13 are both higher than the coating that make by arc ion plating.Spalling and softening were happened on the coating of C21 shear blade after using in factory.The coatings of 12CrMoV and H13 shear blades are excellent after using in factory.