微弧区间伏安特性对Ti及TiN镀层结构与性能的影响

发布时间：2018-01-03 13:23

本文关键词：微弧区间伏安特性对Ti及TiN镀层结构与性能的影响　出处：《西安理工大学》2017年博士论文　论文类型：学位论文

【摘要】：针对磁控溅射镀料粒子离化率低和阴极电弧离子镀存在高温熔滴喷溅等技术不足,依据阴极磁场可约束氩离子对靶面的轰击区域,和在接收到相同强度氩离子轰击时靶面晶界等微缺陷处的电子逸出速率较晶内大约30%,并且电子逸出速率的沿面不均衡度又会被焦耳热效应(Q=I~2Rt)加剧这一等离子体物理学原理,本文通过对磁控阴极与真空腔壁之间电流步进增量和不同模式脉冲电场特性的调控,诱发出以靶电流作为靶面电子逸出总量表征的、靶面微缺陷处电子逸出速率可循环自增的靶面微弧放电状态,由此引发阴极靶面镀料粒子以碰撞诱导热发射方式脱靶。据此研究了具有不同伏安特性的气体放电辉光区、微弧区和弧光区对镀料粒子脱靶方式的影响规律;分析了脱靶方式对离子镀镀层微观结构和力学与摩擦学性能的影响机理,得到如下研究结果:对阴极Ti靶与阳极真空腔体间气体放电伏安特性曲线的测定发现,在直流步进增量式电场模式下,满足磁控阴极靶面诱发微弧放电的最小靶电流密度为0.175 A/cm~2(即辉光放电区和微弧放电区的临界转变靶电流密度为0.175 A/cm~2)。通过对诱发微弧放电后靶面刻痕的观察,阴极靶面呈现离散分布的沟壑状,有别于镀料粒子以级联碰撞脱靶后的不规则凹坑形貌和场致热发射脱靶后的细小圆形融坑形貌。揭示出诱发靶面微弧放电状态可使靶面缺陷区域的镀料粒子由级联碰撞脱靶演变为碰撞诱导热发射脱靶。在微弧放电区间靶电流密度为0.267 A/cm~2时制备的纯Ti镀层,沿靶基距方向的厚度递减速率仅为72.1%,且表现出平整致密的柱状结构(粗糙度Ra为12 nm),而表面并未出现微米尺寸的大颗粒。膜基结合强度的测定结果表明,该镀层的膜基结合力为34.0 N。同时发现,直流步进增量式电场模式虽可诱发出靶面微弧放电状态,但稍长的微弧放电持续时间,则会因微区温升达到甚至超过靶材熔点而产生微区熔融,影响了镀层制备工艺的实施。通过独立调制脉冲条件下靶面峰值电流导通宽度T_(on)和关断宽度Toff,实现既可使靶面始终处于微弧放电状态,又可避免因过度的热积累而致靶面产生微区熔融。同时发现,在T_(on)=24.5μs和T_(off)=0.5μs的脉冲电场模式下,辉光放电区与微弧放电区的临界转变靶电流密度为0.225 A/cm~2。由于诱发与维持微弧放电状态需靶面温升作为前提条件,而脉冲电场较直流电场减缓了靶面的温升效果,确定了脉冲电场模式相较直流电场模式需要更大的靶电流密度才能诱发阴极靶面微弧放电状态。此时,在微弧放电区内,当靶电流密度由0.310增大至0.357 A/cm~2时所制备的纯Ti镀层,沿靶基距方向的厚度递减速率由84降低至80%,而镀层的膜基结合力由15.3增大至25.2 N。揭示出在该脉冲电场微弧放电区间较大靶电流密度条件下,可明显降低镀层沿靶基距方向的厚度递减速率和提升镀层的膜基结合力。利用脉冲电场等通量原理,通过对T_(on)和T_(off)的合理调配,可在相同平均功率下获得较直流电场模式数倍增长的峰值靶电流密度,以此利于实现阴极靶面微弧放电状态的诱发与维持。并且,还构建出一个T_(on)周期内先小后大递进式的双脉冲电场模式,既满足了镀料粒子快速脱靶以获得细小晶粒镀层的高峰值电流的工艺要求,又达到了增加脉冲导通宽度以提高镀层平均沉积速率的效能目标。对采用不同电场模式在微弧放电区相同靶功率下制备纯Ti镀层的研究结果表明:双脉冲电场模式制备纯Ti镀层的平均沉积速率为80nm/min,实际沉积速率为132 nm/min,且镀层具有致密的组织结构和12.0 N的膜基结合力。另一方面,对采用双脉冲电场模式在微弧放电区内不同峰值靶电流密度下制备纯Ti镀层的研究结果表明:当峰值靶电流密度由0.27增大至1.35 A/cm~2时,镀层的平均晶粒尺寸由18降低至10 nm,而镀层硬度由1.2增大至5.6 GPa。说明了在微弧放电区内峰值靶电流密度的增大可以降低镀层的平均晶粒尺寸,能够达到细晶强化的目的。同时发现,采用双脉冲电场模式,在微弧放电区内峰值靶电流密度为0.87 A/cm~2时制备的TiN镀层具有12 nm的平均晶粒尺寸、29.6 GPa的显微硬度、377.1 GPa的弹性模量和5.5×10~(-5) mm/a的腐蚀速率,可为TiN镀层的工艺开发提供一定的参考价值。
[Abstract]:The magnetron sputtering coating material particle ionization rate and low cathodic arc ion plating insufficient high temperature of droplet spray technology, based on the cathode magnetic field can constrain the argon ion bombardment of the target surface area, and to the same intensity of argon ion bombardment in the receiving electronic escape target surface micro defects such as grain boundary at a rate of about 30% in a crystal and, the surface electron escape rate imbalance will be the Joule heating effect (Q=I~2Rt) increased the plasma physics principle, this paper through the increment and electric field characteristics of different pulse mode on the regulation between the magnetron cathode and the vacuum chamber wall current step to induce target current as the target surface electron escape total representation. The target surface micro defect electron escape rate can be recycled from the target surface by micro arc discharge, which caused the cathode surface coating material particles induced by thermal emission mode to miss collision. This paper has the same V The gas discharge glow characteristic, micro arc zone and arc of influence of coating material particle Miss mode; analysis of effect mechanism of distance way coating microstructure and mechanical and Tribological Properties of ion plating, the results obtained are as follows: Determination of Ti cathode and anode target chamber gas discharge I-V curve was found in the field, DC step incremental mode, meet the minimum target current density cathode magnetron target surface induced by micro arc discharge is 0.175 A/cm~2 (critical change target current density glow discharge and micro arc discharge zone is 0.175 A/cm~2). Through the observation of the target surface notch induced by micro arc discharge, the cathode surface showed a discrete distribution the gully, a small circular in coating material particles with dimple morphology and irregular field collision cascade distance after the heat emission after thawing. Miss hole shape reveals the target surface induced by micro The arc discharge state can make the material of plating particles target surface defect area by collision cascade evolved into collision induced thermoemission miss miss. Preparation of pure Ti coating prepared by micro arc discharge in the range of target current density is 0.267 A/cm~2, along the direction of thickness of the substrate to target distance decreasing rate is only 72.1%, and showed a dense columnar structure (the roughness Ra of 12 nm), and the surface does not appear large particles of micron size. The adhesion strength was measured and results show that the coating adhesion force is 34 N. at the same time, DC stepping electric field can induce incremental model of the target surface micro arc discharge state, but the micro arc discharge slightly longer the duration will be due to micro temperature rise reach or even exceed the melting point of target produced micro melting, affecting the implementation of coating preparation technology. Through independent pulse peak under the condition of target current conduction width T_ (on) and off the width of Toff,. We can make the target always in the micro arc discharge state, and avoid excessive heat accumulation caused by target surface micro melting. At the same time, in T_ (on =24.5 s) and T_ (off) =0.5 s pulsed electric field model, the critical electric glow discharge and arc discharge area of target area the current density of 0.225 A/cm~2. due to induce and maintain the state micro arc discharge target surface temperature rise as a precondition, and a DC electric field pulse electric field slows the target surface temperature rise effect of pulsed electric field mode compared with DC electric field model needs to target current density larger induced cathode target surface micro arc discharge state is determined. At this time, in discharge area, when the target current density increases from 0.310 to 0.357 A/cm~2 for pure Ti coating prepared along the direction of the target substrate distance, the thickness decreasing rate decreased from 84 to 80%, and the film substrate coating force increases from 15.3 to 25.2 N. revealed in the Electric pulse micro arc discharge interval of large target current density conditions, can significantly reduce the adhesion of coating thickness along the direction of the target substrate distance decreasing rate and enhance coating force. Using pulsed electric field flux principle based on T_ (on) and T_ (off) distribution, the peak current density than the growth target DC electric field in the same mode several times more than the average power, in order to achieve the target surface induced by cathodic microarc discharge status and maintenance. And also to construct a T_ (on) double pulsed electric field model of progressive period to small, not only to meet the fast particle coating material to obtain fine grain layer distance the peak value of the current technology, and to increase the pulse width to improve the efficiency of the coating deposition rate. The average target of using different electric field model study the preparation of pure Ti coating in microarc discharge area of target power under the same The results showed that the average sedimentation rate of double pulse electric field model for preparation of pure Ti coating is 80nm/min, the actual deposition rate was 132 nm/min, the film substrate and the coating has a dense structure and 12 N force. On the other hand, the double pulse electric field in discharge mode in different target peak current density system study on the preparation of pure Ti coating. The results showed that when the peak target current density increases from 0.27 to 1.35 A/cm~2, the average grain size of the coating decreased from 18 to 10 nm, and the hardness increases from 1.2 to 5.6 GPa. shows increasing in micro arc discharge area peak target current density can reduce the average grain size of the coating. To achieve the purpose of fine grain strengthening. At the same time, the double pulse electric field model, the average grain size in the micro arc discharge zone target peak current density of 0.87 A/cm~2 TiN coatings prepared with 12 nm, 29.6 GPa. The microhardness, the modulus of elasticity of 377.1 GPa and the corrosion rate of 5.5 x 10~ (-5) mm/a can provide a certain reference value for the development of TiN coating.

【学位授予单位】：西安理工大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG174.4

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