钢表面电解液等离子体微弧碳氮共渗层的制备及性能研究

发布时间：2018-01-02 03:10

本文关键词：钢表面电解液等离子体微弧碳氮共渗层的制备及性能研究　出处：《暨南大学》2016年硕士论文　论文类型：学位论文

【摘要】：液相等离子体电解碳氮共渗,又称电解液微弧碳氮化工艺可以在不同金属表面实现快速碳氮共渗。本文首先对45#钢作阴极时的微弧碳氮化过程进行了研究,重点探索了溶液中的放电特征,研究了电解液配方、频率和占空比对起弧条件的影响,分析了电解液中的反应机理;研究了电解液配方、频率和占空比、处理时间对碳氮共渗层组织、结构与性能的影响。对电解渗透放电特性的研究结果表明,起弧电压随导电率、频率和占空比的增加而下降,随尿素浓度的增加而先升后降;起弧时的电流随导电率的增加而上升,随占空比的增加而下降,随频率的增加而先降后升,但是频率和占空比对起弧电压以及电流的影响幅度很小。恒压模式下的电压随电流增加变化的电流电压特性曲线表明放电过程可以分为四个阶段,且阴极承担绝大部分的电压降。阳极产生的是惰性的N2,不能为碳氮共渗提供活性N,只有阴极反应生成的NH3才可以提供活性N;放电过程中,试样表面的温度始终高于电解液中的温度,在微弧放电区域,温度能迅速达到奥氏体温度区。溶液配比对共渗处理的影响为,当电压和处理时间固定时,随着尿素含量的增加,处理后渗层厚度增加。研究发现,KCl导电盐含量通过影响PECN过程电参数来影响渗层质量。PECN处理后试样表面的相组成主要是马氏体、铁氮化合物、铁碳化合物,表面形貌主要呈多孔状,增加频率和降低占空比可以降低表面粗糙度。增大频率和占空比,试样表面的硬度增大,从表层到心部,硬度逐渐降低。增加处理时间可以有效增加渗层厚度。耐磨性测试表明:PECN处理后表面耐磨性和基体相比,得到很大提高,主要的磨损机制是显微切削并伴有少量的疲劳剥落;增加占空比和增加频率会使得表面摩擦因数降低,降低占空比,磨痕变窄。
[Abstract]:Liquid plasma electrolytic carbonitriding, also known as electrolyte micro-arc carbonitriding process, can realize rapid carbonitriding on different metal surfaces. Firstly, the micro-arc carbonitriding process of 4steel cathode is studied in this paper. The discharge characteristics in the solution were studied emphatically, the effects of electrolyte formula, frequency and duty cycle on the arcing conditions were studied, and the reaction mechanism in the electrolyte was analyzed. The effects of electrolyte formula, frequency, duty cycle and treatment time on the structure, structure and properties of the carbonitriding layer were studied. The frequency and duty cycle decreased with the increase of urea concentration. The current increases with the increase of conductivity, decreases with the increase of duty cycle, and then increases with the increase of frequency. But the effect of frequency and duty cycle ratio on starting arc voltage and current is very small. The current voltage characteristic curve of constant voltage mode shows that the discharge process can be divided into four stages. The cathode bears most of the voltage drop. The anode produces inert N _ 2, which can not provide active N for carbonitriding. Only the NH3 produced by the cathode reaction can provide the active N; During the discharge, the surface temperature of the sample is always higher than that of the electrolyte. In the micro-arc discharge region, the temperature can reach the austenitic temperature region rapidly. The effect of solution ratio on the treatment of co-infiltration is as follows. When the voltage and treatment time are fixed, with the increase of urea content, the thickness of osmotic layer increases after treatment. The phase composition of the sample surface after the treatment of KCl conductive salt was mainly composed of martensite, iron and nitrogen compounds and iron carbon compounds by affecting the electrical parameters of the PECN process. The surface morphology is mainly porous. Increasing the frequency and decreasing the duty cycle can reduce the surface roughness. The hardness of the sample surface increases from the surface to the center by increasing the frequency and duty cycle. The hardness decreases gradually and the coating thickness is increased by increasing the treatment time. The wear resistance test shows that the wear resistance of the surface treated with the w / PECN is much higher than that of the matrix. The main wear mechanism is micro-cutting with a small amount of fatigue spalling. The increase of duty cycle and frequency will decrease the surface friction coefficient, reduce the duty cycle and narrow the wear mark.
【学位授予单位】：暨南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG174.4

【相似文献】