基于电压输出波形分析的镁合金微弧氧化负载特性的研究

发布时间：2018-11-13 19:20

【摘要】：本文使用单极性脉冲电源在频率600Hz、占空比30%、正负脉冲比1:0的参数下使用硅酸盐体系电解质溶液进行实验,用LCR测试仪测量不同阶段微弧氧化负载的等效阻抗、电阻、电容值,研究了不同面积下负载电特性的变化规律及不同电特性对电压波形的影响,建立了不同阶段的负载等效电路并利用Multisim软件进行了仿真分析,以验证模型的正确性。通过测量负载电特性发现,随着电压的升高负载的等效阻抗和电阻增大、电容减小,在起弧电压之前阻抗、电阻和电容的变化速率较快,由于在阳极氧化阶段生成的致密氧化膜层对电流的阻碍作用较强,微弧氧化阶段后生成的氧化膜层较疏松对电流的阻碍作用较小;由于面积的增大相当于增加了阳极的导电面积及等效电容两极板的相对面积,所以相同的电压下负载的面积越大等效阻抗和电阻越小、电容越大。随着微弧氧化的进行,负载的电特性不断地在发生变化,这种变化改变了电压波形特性。通过研究发现,负载的面积较小时,电压低于起弧电压时,电压波形趋于直流电压;电压高于起弧电压后,电压波形呈现出放电效应;随着负载面积逐渐增大,在起弧电压之前,电压波形就出现了放电效应。本文分析了不同阶段、不同面积时波形不同的原因,认为上述不同表象,是由于负载电特性和微弧放电通道数量不同而产生。通过波形分析,建立了两个阶段的负载电路模型,即起弧之前为RC串联电路、起弧之后为RC并联后再串联一个电阻R1的电路等效模型,应用Multisim软件仿真该模型对脉冲信号的响应输出,对比实际采集的波形和模型输出波形,二者一致,因此可以证明该模型可应用于微弧氧化负载分析,为今后微弧氧化负载特性的深入研究提供理论模型。
[Abstract]:In this paper, a unipolar pulse power supply with a frequency of 600 Hz, a duty cycle of 30 and a positive and negative pulse ratio of 1:0 is used to carry out experiments with silicate electrolyte solution. The equivalent impedance and resistance of the micro-arc oxidation load at different stages are measured by LCR. The capacitance value, the change rule of load electric characteristic under different area and the influence of different electric characteristic on voltage waveform are studied, the equivalent circuit of load at different stage is established and the simulation analysis is carried out by Multisim software to verify the correctness of the model. By measuring the electrical properties of the load, it is found that with the increase of the voltage, the equivalent impedance and resistance of the load increase, the capacitance decreases, and the impedance, resistance and capacitance change faster before the starting voltage. Because the dense oxide film formed in anodic oxidation stage has a stronger hindering effect on the current, the oxide film formed after the micro-arc oxidation stage has less hindering effect on the current than that on the loose one. Because the increase of the area is equivalent to the increase of the conductive area of the anode and the relative area of the bipolar plate of the equivalent capacitance, the larger the area of the load under the same voltage, the smaller the equivalent impedance and resistance, the larger the capacitance. With the development of micro-arc oxidation, the electrical characteristics of the load are constantly changing, which changes the characteristics of the voltage waveform. It is found that when the load area is small and the voltage is lower than the starting voltage, the voltage waveform tends to DC voltage, and when the voltage is higher than the starting voltage, the voltage waveform shows discharge effect. As the load area increases gradually, the discharge effect of voltage waveform appears before the arcing voltage. In this paper, the reasons for the different waveforms in different phases and different areas are analyzed. It is considered that the above different representations are due to the different electrical characteristics of the load and the number of micro-arc discharge channels. Through waveform analysis, a two-stage load circuit model is established, that is, the circuit equivalent model of RC series circuit before arc start and RC parallel connection and then a series resistance R1 after arc start. Multisim software is used to simulate the response output of the model to the pulse signal. The comparison between the actual collected waveform and the model output waveform shows that the model can be applied to the load analysis of micro-arc oxidation. It provides a theoretical model for the further study of load characteristics of micro-arc oxidation.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.22

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