钛合金阴极液相等离子电解的温度计算与测量

发布时间：2018-05-04 22:07

  本文选题：液相等离子电解 + 温度计算模型　； 参考：《南京理工大学》2017年硕士论文

【摘要】：本文研究了阴极液相等离子电解过程中,Ti-6Al-4V钛合金工件表面温度的计算与测量。研究从直流和脉冲两个方面建立计算模型并验证。直流条件下采用已有的工件-气膜-电解液模型进行计算,并在原有模型基础上修改了假设条件,考虑了电解液挥发消耗热量对于工件表面温度的影响。采用Excel对模型进行计算,并对计算模型进行验证,实验测量结果证明,修正后的直流模型计算数值与测量值能够更好的拟合。直流条件下阴极工件表面温度随着电压升高而增大;在电压不变的情况下,阴极表面温度随着放电时间的延长而降低。脉冲条件下的温度模型以一个脉冲周期为单位,讨论断电阶段工件表面热传导的不同情况,建立了三种物理模型,分别考虑断电阶段工件与电解液之间存在蒸汽膜并发生热交换、工件与电解液直接发生热交换、工件不与外界发生热交换三种情况,并根据边界条件进行求解得到了脉冲条件下阴极工件工件表面的温度计算模型。将计算值与实验测量值相拟合,发现在断电阶段不考虑工件与外界的热交换的情况下,计算模型最符合测量结果。在脉冲电压下,工件表面温度随着占空比的增大而上升;而脉冲电压的频率减小,阴极起弧所需的电压增大,但是频率对于阴极工件表面温度的影响不大。对直流和脉冲条件下不同温度对工件表面渗层形貌与性能进行分析。在直流条件下,随着表面温度的升高,渗层的厚度增加,硬度同时也得到提高,Ti-6Al-4V表面温度到达847℃时,处理20min能够在表面得到约100μm厚的渗层,渗层中主要为钛的氧化物和碳氮化物,渗层中最大硬度可以达到1287.8HV0.1。脉冲条件下Ti-6Al-4V表面温度升高同样能使渗层厚度增加,在867℃C时得到的渗层约为110μm,但是渗层中出现断裂和剥落的现象较为严重。
[Abstract]:The calculation and measurement of workpiece surface temperature of Ti-6Al-4V titanium alloy during cathodic liquid plasma electrolysis have been studied in this paper. The calculation model of DC and pulse is established and verified. The existing workpiece-film-electrolyte model is used for calculation under DC condition. The hypothesis is modified on the basis of the original model, and the influence of the volatile heat consumption of electrolyte on the surface temperature of the workpiece is considered. Excel is used to calculate the model and verify the calculation model. The experimental results show that the modified DC model can better fit the calculated value and the measured value. The surface temperature of cathode workpiece increases with the increase of voltage under DC condition, and decreases with the prolongation of discharge time under the condition of constant voltage. The temperature model under pulse condition is used as a unit of pulse period to discuss the different conditions of heat conduction on the surface of workpiece during the period of power failure, and three kinds of physical models are established. Considering the existence of steam film and heat exchange between workpiece and electrolyte during power off stage, the heat exchange occurs between workpiece and electrolyte directly, and there is no heat exchange between workpiece and outside. According to the boundary condition, the temperature calculation model of cathode workpiece surface under pulse condition is obtained. By fitting the calculated values with the experimental measurements, it is found that the calculation model is the most suitable for the measurement results when the heat exchange between the workpiece and the outside world is not considered in the power off stage. Under the pulse voltage, the surface temperature of the workpiece increases with the increase of duty cycle, while the frequency of the pulse voltage decreases and the voltage required for the cathode arcing increases, but the frequency has little effect on the surface temperature of the cathode workpiece. The morphology and properties of the coating on the surface of the workpiece were analyzed at different temperatures under DC and pulse conditions. Under DC condition, with the increase of surface temperature, the thickness of permeation layer increases, and the hardness is also increased. When the surface temperature of Ti-6Al-4V reaches 847 鈩，

本文编号：1844873