Control And Monitor System To The Process Of Micro-arc Oxidation Of Magnesium Alloy

Magnesium alloy micro-arc oxidation (MAO), is a complicated processgenerating ceramic layer witch used the Micro-plasma oxidation engender by arcdischarge. The main way is infliction a voltage on the work-piece, using a certaincurrent density to arose the Micro-arc discharge and spark discharge on thework-piece, make it to finish the Thermo chemical, electrochemical and plasmachemical reaction, make it a condition that to generating ceramic layer, through thisway to actualize Modified the surface of the work-piece and strengthen.According to the relevant research results and experiment, in allusion to the MAOprocess, the separate local arc discharge mechanism and the growth of MAO filmmodel. Micro-arc discharge mechanism and models were put forward based on theMAO arc physics theory. The separate arc model is described as4courses: creatinggas from electrolysis, arc discharging, metals oxidizing, cooling and shrinking ofoxides. The oxygen-based gas mixtures, which coming from water electrolysis andanodic oxidation, attached to conductive channel; when the gas closed channel andstood the supply voltage and ionization, arc discharge occurs. Partially hightemperature will cause the formation of intense oxidation of the metal. And the heatgenerated by oxidation will increasingly improve the local temperature leading toeven more intense discharge. The oxides in conductive channel melt and emit fromchannel and Contact with the solution, large temperature difference results in sharpcontraction of melt, and the metal substrate has a higher thermal conductivity, so theshrinking hole left inward. A separate local arc discharge will result in amicro-thermal cycle process, the temperature of which rises quickly and concentrated.With the arc extinguished, it rapidly transferred to the cooling process. In the practiceexperiment of micro-arc oxidizing and large-arc discharge3stages in turn with sourcevoltage increasing: Anodic oxidation, micro-arc oxidation and arc discharge stage.The process control system on the micro-arc oxidation experimental platform Hasbeen designed, it used AT89C52MCU as function of the core, two system: powercontrol system an process control system, their connected as20mA current loop serialasynchronous communication interface. In this design, through the RS232serialcommunication interface between PC and machine connection, used Visual Basic todesign interface. Compared with the process control system we already have, add thedetection function of micro-arc oxidation process parameters, Can be achieved thetarget what dynamic rendering of voltage, current waveform curve.Based on the analysis of micro-arc oxidation process, aim at the actualrequirements for the industrial production of micro-arc oxidation, put forward twoprocess control mode and a set of process parameters. based on the processmonitoring system designed, real-time monitoring of various parameters in themicro-arc oxidation process, And is given a set of the process parameter database for practical application. A certain extent, improve production efficiency and productquality estimates, to provide support for MAO processing centers in the future...