| Ti6Al4V alloy, with its good corrosion resistance and biocompatibility, and elastic modulus close to human bones, is widely applied in biomedical fields. But Ti6Al4V alloy is very poor on wear resistance and do not wear-resistant. Surface coating and modification to solve the challenges of its wear-resistance is one of economical and effective technical means. The N+ injection and Nitride layer, TiN films and DLC films in Ti6Al4V alloy substrate were respectively obtained by high frequency low voltage plasma immersion ion implantation, unbalanced magnetron sputtering and DC magnetic filter cathode vacuum arc source deposition, and the impact-wear property and wear mechanism of them were investigated,which is important in medical applications and theoretical.This development has a small impact load reciprocating motion of the test machine. And Ti6Al4V alloy substrate and modified layers were studied with the impact test on the machine. Using optical microscope (OM), X-ray Diffraction (XRD), scanning electron microscope (SEM), Energy Disperse Spectroscope (EDS) and Level and so on, matrix of Ti6Al4V alloys and impact abrasive wear behavior of modified layers were investigation,the whole test of the main conclusions are as follows:1. The main technical performance parameters (impact load F, impact cycle N, impact frequency f, etc.) of the testing machine for impact wear is flexible and sample clamped is convenient. The sphere-plane was used of the impact system that is versatile. The microcomputer control system was adopted, with controllable and test accuracy. The testing machine is used in the general project status; the impact test indicates that the machine can be used basic tool for a small load impact-wear.2. The depth of the impact-scar of Ti6Al4V and the modified sample is increase along with the increase of impact cycles, but non-linear relationship. The process of impact-wear can be divided into three stages, absence of wear (â… ), slight wear (â…¡) and severe wear (â…¢). With the impact load reduced, the impact-cyclesis increase in stageâ… andâ…¡, wear process of material is slowed down; otherwise, wear process of material is accelerating. During three stages, the impact-cycles of specimen experience in absence of wear stage are relatively decreasing, and remain relatively long impact-cycles in slightly wear stage, which closely related to the micro-changes of specimen surface. Fatigue peeling is common failure mechanism in severe wear in all samples which showed the process of impact wear was a compound process of wear and fatigue.3. Ti6A14V alloy has a largest plastic deformation in all samples, and the failure mechanism of Ti6A14V alloy is mainly adhesion wear and fatigue peeling. Nitrogen ion implantation and nitrogen treatment can effectively prevent the crack extension and slow down the process of serious wear of the samples; at the same time, Ion implantation and nitrogen treatment can reduce adhesion properties under a small impact load, thereby enhancing impact wear-resistance ability of the sample. Impact-wear mechanism on unbalanced magnetron sputtering TiN film is mainly plastic deformation and fatigue peeling; compared with the matrix of Ti6Al4V alloy, study shows that the critical impact- cycles of TiN film has improved than the matrix material significantly.Mostly because of higher hardness of TiN thin films, surface residual compressive stresses and the low surface roughness. Using magnetic filtered cathodic vacuum arc deposition method the DLC films thickness of two have high impact wear-resistance, owing to the DLC films is an amorphous structure that is composed of tiny particles, high hardness, good bonding strength between coating and substrate. DLC1 films of thickness of 303.9nm are better than DLC2 films of thickness of 70.2mn in impact-wear performance, which is related to the films thickness and structural characteristics.4. The failure process of the sample under a small repetitive impact load may be summarized as:plastic deformation, crack initiation, extension and peeling; and hold that the main factory on affect the wear life of the sample contains surface roughness, hardness, film-substrate bond strength and surface residual stress and so on. Experiment show that repeated impact-wear process is cumulative damage of material processes. In order to increase impact wear-resistant performance of material, it requires not only material surface has a high hardness and resistance to plastic deformation of the sample, but also material surface is equipped with crack of delay time and the ability to reduce crack expansion speed under stress propagation. The processes of modification enhance the surface hardness of Ti6A14V alloy and increase the ability of resistance to adhesive wear and contact fatigue wear; while strengthening the surface of Ti6A14V alloys, ensuring a good film-substrate binding, the sample surface with high strength and toughness, delaying the crack initiation and expansion.
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