以TiN、TiAlN为主的过渡族金属氮化物硬质涂层以其较高的表面硬度、良好的耐磨以及抗高温氧化性能,被广泛应用于材料表面防护涂层.然而,涂层内部积聚的高内应力却容易引发涂层与基体的结合力问题.利用PVD技术很难在材料表面制备出厚度超过10μm的TiN或TiAlN涂层.多层复合结构能够有效控制涂层中的应力分布,从而使得其成为获得较厚硬质涂层的一种有效方法.本工作在TC4合金以及Si (100)基体上利用等离子增强离子镀技术制备了具有不同复合层数的多层Ti/TiN涂层,并研究了复合层数对涂层力学性能的影响.结果表明,随着复合层数的增加,涂层的各项力学性能得到了显著强化.涂层的显微硬度nV0.25高达27500MPa,厚度大于50 μm,且具有较好的韧性.涂层的韧性与显微硬度成正比例关系.同时,48层复合结构的Ti/TiN涂层具有低于0.35的摩擦系数以及最佳的抗磨损性能.然而,随着复合层数的进一步增加,涂层与基体的界面结合强度显著弱化.
Metal nitride hard coatings,such as TiN and TiA1N are widely used to protect materials because of their higher hardness and wear properties.However,these coatings always contain a high degree of internal stress which could arouse adhesion problems.It is hard to synthesize monolayer TiN or TiA1N coatings thicker than 10 μm by PVD (physical vapor deposition).The multilayer composite structure,offering efficient means of controlling residual stress,is a successful way to synthesize thicker hard coatings.In the present study,a series of multilayer composite Ti/TiN coatings with different composite periods were synthesized by plasma enhanced ion plating and the effects of multilayered structure mechanical properties of the coating was studied.The result shows that the mechanical properties of the coating are strengthened with increasing the periods of composite Ti/TiN layer.The micro hardness (HV0.25) can reach to about 27 500 MPa and better toughness and higher thickness (＞50 μm) are obtained.The toughness of the coating is almost directly proportional to hardness.Meanwhile,the tribological performance of the coating is improved with a lower dry friction coefficient (about 0.35) and higher wear resistance by alternating 48 periods of Ti/TiN layer.However,the bonding strength of the coating is weakened with further increasing the period of Ti/TiN layer due to the weak interface of coating and substrate.
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