Preparation And Performance Of TiN Films On The Surface Of 30CrMnTi Alloy

With the development of special machinery, the special cutting tools are required to be of better quality and longer lifetime, which has always been realized by the hard coating on the surface of tools. However, there are many reasons to cause failure in the hard coatings due to its structure and working environment,among which the bad combination of interface between the substrict and coatings is the main reason. Therefore,it is of much importance to analyze the factors resulting in failure to improve the quality of the matrix and accordingly to ameliorate the strength of the combination between substrate and coatings.Aiming at to improve the quality of 30CrMnTi steel, this paper prepared TiN coatings on Grinding strengthened steel by IP-PVD method. The mechanism and influence of different factors has been studied. Then the microscope, SEM, X-RD and EDS have been employed to investigate the phase change in substrate, the structure transformation in strengthen layer and the properties fo TiN coatings.The results indicated that the modulated 30CrMnTi steel is mainly composed of Troostite and Ferrite. Coating directly on the modulated steel without grinding strengthening lead to lower hardness, bad surface bonding with the strength of only about 10N. Though the hardness of the TiN coating has been improved to some degree, the wear resistance was not ideal. 450 ℃ and 750V negative bias contributed to an increased tough particles and more craters, splitting the integrity of coatings, constricting the development of wear resistance.On the other hand, coating on the modulated steel with grinding strengthening brought out good results in the interface strength, hardness and wear resistance. And 440 ℃ would not cause film transformation. In a word grinding hardening has remarkably improved the bonding strength.It is concluded that grinding hardening technique is conducive to the polishing degree and surface hardness, which is an effective support in the preparation of TiN coatings to improve the bonding strength of TiN/30CrMnTi.