电沉积Ni-ZrC复合镀层的织构及内应力研究

发布时间：2018-02-11 21:09

本文关键词： 电沉积 X射线衍射 Ni-Zr C 织构内应力组织结构　出处：《上海交通大学》2015年博士论文　论文类型：学位论文

【摘要】：电沉积镍基复合镀层的织构、内应力及组织结构,决定了镀层的性能表现。复合镀层中第二相颗粒的存在,使得复合镀层的织构、内应力及组织结构不同于纯金属镀层。本文通过复合电沉积技术,制备了微米Zr C(mZr C)和纳米Zr C(nZr C)颗粒复合镍基镀层,研究了电沉积参数、镀液中Zr C颗粒浓度及颗粒尺寸对Ni-Zr C复合镀层的织构、内应力及组织结构的影响。利用X射线衍射(XRD)分析技术,对Ni-Zr C复合镀层的织构、内应力及组织结构的影响因素、调整方法、形成及变化机制等进行了研究分析。利用相对织构系数、Rietveld全谱拟合极图以及XRD实测极图,研究了镍基复合镀层中的织构随电沉积参数、镀液中颗粒浓度及颗粒尺寸的变化,三种分析方法所得结果一致。随着电流密度的升高,Ni-Zr C复合镀层逐渐呈现出[200]丝织构,而随着颗粒浓度的升高,镀层的[200]丝织构逐渐消失。在相同的电流密度及颗粒浓度时,Ni-nZr C镀层的[200]丝织构强度低于Ni-mZrC镀层。研究了镍基镀层的织构在电沉积过程中的变化,发现在电沉积Ni以及Ni-Zr C镀层的初期,镀层均呈现出[111]初始织构,随着电沉积过程的进行,Ni镀层逐渐呈现出[200]强织构,而Ni-Zr C复合镀层的晶体择优取向则逐渐消失。Ni-Zr C镀层织构随着ZrC颗粒浓度的变化可以分为两个阶段,在第一阶段中,镀层的丝织构随着颗粒浓度的升高而被不断抑制;而在第二阶段,镀层几乎不存在择优取向,并不再随ZrC颗粒浓度而变化。本文结合Voigt均应力和Reuss均应变模型,通过修正Hill加权平均模型的方法,对具有丝织构镀层的X射线应力测试方程进行修正。利用优化的X射线应力分析方法,研究了Ni-Zr C复合镀层中的内应力随电流密度、颗粒浓度及尺寸的变化,发现Ni-ZrC镀层内应力随电流密度变化不大,而随着镀液中颗粒浓度的升高而降低。在相同的电流密度及颗粒浓度时,Ni-mZr C镀层的表面拉应力高于Ni-nZr C镀层。发现Ni及Ni-Zr C镀层内应力在电沉积过程中,随着镀层厚度的增加而先降低后升高。研究了电沉积过程中的超声波处理、对基底施加预加拉应力以及后续热处理手段调整镍基镀层的内应力状态,发现该三种方法都可以降低镍基镀层表面拉应力,而利用热处理的方法可以将镀层的内应力状态由拉应力调整为压应力,并且压应力的值随热处理温度的升高而升高。利用XRD单峰线形分析以及Rietveld全谱拟合,研究了Ni-Zr C镀层组织结构随电沉积参数及Zr C颗粒浓度及尺寸的变化规律。镀层组织结构的变化也可以分为两个阶段,在第一阶段,随着颗粒浓度的增加,[200]相关的晶粒尺寸不断降低,而[111]及[220]相关的晶粒尺寸则变化不明显;在第二阶段,随着颗粒浓度的增加,晶体择优取向没有较大改变,各方向相关的晶粒尺寸不断降低,各(hkl)晶面相关的显微畸变不断升高。结合织构变化规律,将这两个阶段分别称为织构调整阶段和晶粒细化阶段。利用退火处理及XRD分析技术,计算得到了Ni-Zr C镀层的晶粒长大激活能,在低温时为51.88 KJ/mol,在高温时为112.9 KJ/mol。探讨了镀层的力学性能与电沉积条件的关系,发现随着镀液中Zr C颗粒浓度的升高或电流密度的降低,Ni-mZr C镀层硬度不断增大,最大值达到475 HV左右,而Ni-nZrC复合镀层的显微硬度则先增大后减小,镀层硬度最大值约为435 HV。利用原位X射线分析技术,对Ni-mZrC镀层的力学性能进行研究,计算得到了其杨氏模量、泊松比及屈服强度分别为:236 GPa、0.297以及290 MPa。
[Abstract]:The texture of electrodeposited nickel based composite coating, internal stress and organizational structure, determines the performance of the coating. The second phase particles in composite coatings, the texture of the composite coating, internal stress and organizational structure is different from the pure metal coating. The composite electrodeposition technology, micro Zr to prepare C (mZr C Zr C (nZr) and nano C particles) composite nickel coating, on the electrodeposition parameters, plating particle concentration and particle size of Zr C liquid Ni-Zr C composite coating on the texture of the effect of internal stress and organizational structure. By using X ray diffraction (XRD) analysis technology, texture of Ni-Zr C composite coating the influence of stress factors, organizational structure and the adjustment method, the formation and change mechanism were studied. The relative coefficient of texture, Rietveld whole pattern fitting pole figure and XRD measured polar diagram, texture of Ni based composite coating with the electrodeposition parameters of plating The variation of particle concentration and particle size in the solution, the three methods of analysis. The result is consistent with the increase of current density of Ni-Zr C composite coatings gradually showing [200] fiber texture, and with the increase of particle concentration, coating the [200] texture gradually disappear. At the same current density and particle concentration, Ni-nZr C coating the [200] fiber texture strength is less than that of Ni-mZrC coating. The change texture of nickel coating in the electrodeposition process, found in the electrodeposition of Ni and Ni-Zr C were the early [111] coatings show the initial texture, with the deposition of Ni coating, showing a strong [200] texture and Ni-Zr C composite coating the crystal orientation gradually disappeared.Ni-Zr C coating texture change with ZrC particle concentration can be divided into two stages. In the first stage, coating fiber texture with the increase of particle concentration is constant Inhibition; and in the second stage, the coating has almost no preferred orientation, and no longer with the ZrC particle concentration change. The uniform stress and Reuss strain model of Voigt in this paper, the correction method of the Hill weighted average model, the stress test equation is modified with X ray texture coating. Using X ray optimization the method of stress analysis, the stress of Ni-Zr C composite coating with the current density of the variation of particle concentration and size, found little change with the internal stress of coating Ni-ZrC current density, and decreases with increasing particle concentration in the bath. The current density and particle concentration in the same time, the surface of Ni-mZr C coating the tensile stress is higher than that of Ni-nZr. Ni and Ni-Zr found that C coating C coating stress in the electrodeposition process, with the increase of coating thickness and increased after the first reduction. The effects of ultrasonic treatment during the electrodeposition process, the basal fertilizer Gallas and pre stress and subsequent heat treatment of nickel based coating method to adjust the internal stress status, found that the three methods can reduce the nickel coating surface tensile stress, and using the method of heat treatment can be plating internal stress from tensile stress to compressive stress and compressive stress value with the increase of heat treatment temperature increased. Using the XRD linear unimodal analysis and Rietveld whole pattern fitting, studied the change law of Ni-Zr C coating structure with the concentration and size of electrodeposition parameters and Zr C particles. Changes in coating structure can be divided into two stages, in the first stage, with the increase of particle concentration [200], the grain size decreases, while the [111] and [220] related to the grain size did not change significantly; in the second stage, with the increase of particle concentration, the crystal orientation is not changed, the direction of grain size Inch (hkl) decreases, the crystal surface micro distortion related rising. With variation of texture, the two phases are called texture adjustment stage and grain refinement stage. By annealing and XRD analysis, calculated the grain growth activation energy of Ni-Zr C coating, when the low temperature is 51.88 KJ/mol at high temperature is 112.9 KJ/mol., discusses the relationship between the mechanical properties and coating deposition conditions, it was found that with the decrease of Zr increased C in the plating solution of particle concentration and current density, Ni-mZr C hardness increases, the maximum value of 475 HV, and the microhardness of Ni-nZrC composite coating is increased first and then decreased. The maximum hardness of the coating is about 435 HV. by in situ X ray analysis technology to research the mechanical properties of Ni-mZrC coatings, the young's modulus, Poisson's ratio and yield strength were 236 GPa, 0.297 and 2 90 MPa.

【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ153

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