Production of Tin Films by Ion Beam Mixing Method and Clarification of Its Fatigue Fracture

利用离子束技术制备的陶瓷薄膜，可以对其机械、光学、电学和化学性能进行改性。在本研究中，使用两种离子束技术来获得TiN薄膜和CrN薄膜。将这种陶瓷薄膜涂覆在不同结构、成分和膜厚的600 Mpa级高强度钢上。在动态混合法中，薄膜中的钛与氮的比例可以通过沉积条件来改变。当薄膜比为1：1时，几种薄膜中硬度最高。硬度随钛体积分数的增加而降低。此外，TiN薄膜的结构依赖于TiN和Ti2N的混合物，并且随着TiN体积分数的增加，TiNx薄膜呈现出更精细的结构。在这种情况下，薄膜的硬度随着TiN体积分数的增加而增加，疲劳行为取决于涂层薄膜。当在钢上形成TiN薄膜时，疲劳寿命延长。这种疲劳行为是疲劳裂纹萌生过程的结果。涂层延缓了裂纹的萌生。裂纹萌生的延缓作用与薄膜的结构和硬度密切相关。当薄膜组织细小且硬度较高时，薄膜沉积可显著提高疲劳寿命。然后，随着薄膜的层压，疲劳寿命增加。薄膜的分层使薄膜内部产生残余压应力，薄膜结构变得更加细小。

The ceramic thin films produced by ion beam technology, can modify the mechanical, optical, electronic and chemical properties. In the present study, two ion beam technologies were used to obtain the TiN films and CrN films. Such ceramic thin films were coated onto 600 MPa grade high tensile strength steel with varying the structure, compostion and film thickness. In dynamic mixing method, the ratio of Ti to N in the film can be changed by the deposition condition. When the ratio value of film is 1 : 1, there is the greatest hardness among the several thin films. The hardness decreases with increasing volume fraction of Ti. Furthermore, the structures of TiNx films depend on the mixture of TiN and Ti_2N and show more fine structure when the volume fraction of TiN increases. In this case, the hardness of film increases with increasing the volume fraction of TiN.The fatigue behavior depends on the coating thin film. When the TiN film is produced onto the steel, the fatigue life enlarges. Such a fatigue behavior results from the fatigue crack initiation process. Coating the film delays the crack initiation. The retardation of crack initiation markedly depends on the film structure and hardness. When the film structure is fine and its hardness is great, the fatigue life is strongly enhanced by the film deposition. Then, the fatigue life increases with laminating the thin film. The compressive residual stress into the film arise from the lamination of film, and then the film structure becomes more fine.