自润滑氮化钒基复合涂层制备及宽温域摩擦磨损特性研究

发布时间：2018-03-22 16:48

本文选题：屈服抗力　切入点：VN基涂层　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：随着现代航空、航天、核电等高新技术产业的飞速发展,铝合金、镍合金、钛合金等高强度金属的高速大功率切削对先进的刀具涂层材料及技术提出了迫切而苛刻的要求。在高速、高强度及大功率等切削条件下,切削温度经常升高至700°C,从而刃口与工件不可避免地处于高温、变温、氧化等恶劣工况中,传统涂层难以在宽温度范围内保持较低的摩擦系数及磨损率,严重制约着我国金属加工质量的提高和高性能切削机床的发展。因此,开发优良的宽温域自润滑涂层,对推动我国高性能切削刀具及机床的发展具有重要的理论和实际应用价值。本文基于多弧离子镀技术研制了VN(氮化钒)基自润滑复合涂层,通过数值方法研究了VN基复合涂层/基体系统在不同涂层厚度及弹性模量下的屈服规律,探索了VCN(碳氮化钒)及VN/Ag(氮化钒/银)复合涂层在宽温度范围内的摩擦及磨损特性,并进一步揭示了滑动条件对VCN涂层摩擦学特性的影响机制。建立了VN基复合涂层与刚性平面微观接触的平面应变模型,研究了VN基涂层/基体系统压缩形变的临界屈服特性,结果表明:超厚涂层的初始屈服位置位于接触中心下一定深度处,且深度随泊松比变化呈单调增加规律。推导了超厚VN基复合涂层初始屈服的临界条件。对于较薄涂层,研究了VN基涂层/基体系统在不同涂层厚度及弹性模量下的屈服规律,结果表明涂层/基体系统的塑性区或脆性裂纹随参数变化可能萌生于涂层、基体内或其界面处,增大VN基复合涂层与基体弹性模量的差值可降低系统的屈服抗力。通过在N2及C2H2气氛中蒸发V靶制备了VN和VCN涂层,由结构研究可知C元素在VCN涂层中主要形成sp2C-C及sp3C-C杂化键,杂化键改变了VCN涂层的形貌、晶面取向及晶粒尺寸,增加了VCN涂层的硬度及弹性模量,然而减小了涂层与基体的结合力,研究了VN和VCN涂层在25°C、300°C、500°C及700°C下的摩擦学特性,发现杂化键在25°C~500°C范围内能够明显减小VCN涂层的摩擦系数及磨损率,然而在700°C下失去效果。研究了N2流量变化对VCN涂层厚度的影响,发现在-50 V基体偏压、60sccm C2H2流量、60 A靶电流下,氮气气体量为350 sccm基本达到了涂层合成的反应用量,随后增长未使涂层厚度发生明显改变。设计了L4(23)正交试验,研究了载荷、温度及滑动频率对VCN涂层摩擦磨损特性的影响机理,获得了VN和VCN涂层适应的相对滑动条件。通过在N2环境中蒸发V、Ag靶制备了VN-VN/Ag自润滑复合涂层,发现Ag元素在VN晶格中形成了纳米晶粒,增大了复合涂层的表面粗糙度,改变了复合涂层的择优取向晶面。通过结合强度和力学性能评价表明,VN-VN/Ag自润滑涂层与VN涂层相比具有较高的结合力,而具有较低的硬度及弹性模量。研究了VN-VN/Ag自润滑涂层在25°C~700°C之间的摩擦磨损特性,结果表明金属Ag提高了复合涂层在室温及300°C下的摩擦学性能,而在500°C及700°C下V2O5、Ag3VO4及Ag VO3等氧化物是涂层产生润滑作用的关键因素。进一步考察了异质及过渡界面VN/Ag多层涂层的结构、力学及宽温域摩擦磨损特性,结果表明过渡界面的Ag含量相对异质界面的含量值降低48 wt.%,V含量相应升高71 wt.%,此外,过渡界面涂层具有较高的承载能力和抗失效性能。通过摩擦学研究发现过渡界面涂层在室温下与异质界面涂层相比具有较低的摩擦系数,在300°C下由于摩擦表面Ag贫乏两种多层涂层具有较高的摩擦系数,在500°C和700°C下,Ag元素加速了向摩擦表面的迁移与扩散,生成了剪切强度较低的钒酸盐和偏钒酸盐,因而两种涂层的摩擦系数相对较低。
[Abstract]:With the rapid development of modern aviation, aerospace, nuclear power, and other high-tech industries Aluminum Alloy, nickel alloy, high speed and high power cutting titanium alloy high strength metal and proposed the urgent demands on tool coating materials and advanced technology. In high speed, high strength and high power cutting conditions, cutting temperature often increased to 700 DEG C, thereby cutting edge and workpiece inevitably at high temperature, temperature, oxidation and other adverse conditions, the traditional coating is difficult to maintain the low friction coefficient and wear rate in a wide temperature range, which restrict the development of our country to improve the quality of metal processing and high performance cutting machine. Therefore, wide the temperature field of developing excellent self lubrication coatings, has important theoretical and practical value to promote the development of China's high performance cutting tool and machine tool. In this paper, multi arc ion plating technique is developed based on VN (nitrogen vanadium) based self lubrication Sliding composite coating was studied by using numerical method of VN based composite coating / substrate system under different coating thickness and elastic modulus of the yield rule, to explore the VCN (vanadium carbonitride) and VN/Ag (vanadium nitride / Ag) composite coating on friction and wear characteristics of wide temperature range, and further reveals the impact of the mechanism of sliding conditions on the tribological properties of VCN coatings. The plane strain model of VN composite coatings and rigid plane micro contact, the study of VN based coating / substrate system compression deformation critical yield characteristics, the results show that the initial yield of super thick coating is located in contact center at a certain depth, and depth with Poisson change monotonically with the increase law. The critical conditions are super thick VN composite coatings. The initial yield for the thin coating of VN based coating / substrate system under different coating thickness and elastic modulus of the yield. Law, results show that the coating / substrate system of plastic zone or brittle crack along with the change of the parameter matrix in the coating may be adorable born, or at the interface, the difference increases with the increasing of VN based composite coating and matrix elastic modulus can reduce the system yield resistance. Through the evaporation of V target in N2 and C2H2 atmosphere in the synthesis of VN and VCN the research shows that coating structure of C element in VCN coating is mainly formed in sp2C-C and sp3C-C bonded and bonded changed the morphology of VCN coating, crystal orientation and grain size, hardness and elastic modulus of VCN coating increased, but reduced the coating and the substrate bonding force, VN and VCN coatings at 25 DEG C study on the tribological properties of 300 ~ C, 500 ~ C and 700 ~ C, it was found that the friction coefficient of hybrid bond can obviously reduce the VCN coating in 25 ~ C~500 ~ C range and wear rate, but lost the effect at 700 ~ C. The effects of N2 flow rate on the VCN coating thickness. Ring, found in the -50 V 60sccm C2H2 flow, substrate bias voltage, 60 A current, the nitrogen gas volume of 350 SCCM basically reached the synthesis reaction coating amount, then growth does not cause the coating thickness is changed obviously. The design of L4 (23) orthogonal test, studied load, temperature and sliding friction frequency influence mechanism the wear characteristics of VCN coatings obtained relative sliding conditions VN and VCN coating adaptation. Through evaporation in the environment of N2 V, VN-VN/Ag self-lubricating composite coatings Ag target system, Ag elements to form nanoparticles in VN lattice, increases the surface roughness of the composite coatings, changed the crystal orientation the surface composite coating. By combining the evaluation of strength and mechanical properties showed that VN-VN/Ag self lubricating coating and VN coating adhesion compared with high hardness and elastic modulus, and has low. Research on VN-VN/Ag self lubricating coating at 25 DEG C~700 DEG C The friction and wear properties between the metal, results show that Ag improves the tribological properties of the composite coating at room temperature and 300 DEG C, and in 500 ~ C and 700 ~ C V2O5, Ag3VO4 Ag and VO3 oxide is a key factor in coating lubrication. Further study of structural heterogeneity and transition interface VN /Ag multilayer coating the friction and wear properties of mechanics and wide temperature range, results show that the content of Ag transition interface relatively heterogeneous interface value decreased 48 wt.%, V content increased 71 wt.%, in addition, the transition interface coating has high bearing capacity and anti failure performance. Through the study found that the tribological transition interface coating at room temperature with heterogeneous interface coating compared with low friction coefficient, the friction coefficient at 300 ~ C due to friction surface Ag poor two multilayer coating with high, at 500 DEG C and 700 DEG C, Ag elements to accelerate the transfer of the friction surface With the diffusion, the low shear strength vanadate and partial vanadate have been formed, so the friction coefficient of the two coatings is relatively low.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG174.4

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