The weld and surface treatment equipment have been highly approved to improve joint performance.The mechanical properties,corrosion resistance,friction and wear performance of joints have seen as the focus for researchers in the field of large pressure vessel,chemical reaction kettle,ship structure etc.However,the high quality surface modification is difficult after the work-piece welded because of the problem of clamping,siting and the power of equipment.Weld and micro-arc oxidation(MAO)equipment integrated into an on-line equipment to solve the work-piece welding and surface treating becomes a key technology.To guarantee the joint mechanical properties and increase their anti-corrosive and wear-resistance for the similar space narrow nuclear island pipeline welding operation scene,an integrated power supply was manufactured,which consist of a gas tungsten arc weld(GTAW)power and micro-arc oxidation power.To guarantee the performance of joints,the methods of 200 k Hz current chopping modulation and cerium oxide doped MAO coatings was investigated.The influence of chopper frequency on current and inductance on current were analyzed.The stability of current was improved by using the 200 k Hz current chopping modulation.Moreover,the influence of CeO2 doped MAO coatings on process of MAO,time vs.voltage,thickness of coatings,band gap of coatings were analyzed.The corrosion and wear resistances of work-pieces were improved by CeO2 doped MAO coatings.On this basis,the pulse waveform and load characteristic were studied.The theoretical basis for the development of integrated power supply was provided.To realize the integration of GTAW and MAO power supply,meet the function of positive polarity,variable polarity and MAO constant current,the structure of integrated power was designed and the main circuit and control module were developed.The main circuit was designed,which consisted of a buck step-down module,a full bridge power inverter module,a whole bridge of function inverter module,a 200 k Hz chopper module.The transfer functions of the buck step-down module and full bridge power inverter module were extracted,and the closed-loop control model of 200 k Hz chopper module was established,the influence of duty ratio and load on frequency characteristic were analyzed,and the rationality of the design was verified.Meanwhile,the core of control module was developed by ARM and FPGA.Consequently,an important basis for the research of integrated power control strategy was provided.To realize the current control,arc voltage regulation,function of integrated power supply,the integrated power control strategies were studied.The current rising and falling edges,and PID control technology were studied to revise the current pulse output.Furthermore,the arc voltage regulation was developed,and primary sampling,background sampling and continuous sampling were designed.Meanwhile,two cascade control strategy was used to control the power inverter and function inverter,stable output voltages and currents were obtained for the polarity GTAW mode,variable polarity GTAW mode,MAO constant current mode.The integrated power supply was investigated in the experiment of weld.The external characteristic,dynamic characteristics and contrast experiments between integrated power and conventional power were studied,the structure of feature zones and the joint tensile strength were analyzed.Results show the superiority of integrated power supply.Meanwhile,the experiment of pure titanium and aluminum alloy by integrated power supply were researched.Effect of current on weld forming,tensile strength and micro-structure of welded joint were researched.The experiment results show that the requirements of polarity GTAW mode and variable polarity GTAW mode were satisfied,which supported the surface modification of the MAO.The MAO experiment of integrated power supply were studied.Comparison experiment of on-line MAO and conventional MAO was researched,the influence of current density and the speed of form coatings were studied.Moreover,the experiment of pure titanium and aluminum alloy joint MAO were developed,the differences of MAO coatings in different regions of the joint were researched.To improve the corrosion resistance and wear resistance,the EPD-Enhanced MAO(EEMAO)technology was used to make the CeO2-TiO2,CeO2-Al2O3 composite coatings,the effects of current density and CeO2 concentration on the micro-structure and properties of the coatings were analyzed.Experimental results show that current density of on-line MAO was higher than that of the electrolytic cell MAO,the speed of form coatings was higher.The corrosion resistance of the joints were improved.And the corrosion and wear resistance of pure titanium and aluminum alloy MAO coatings were improved via EEMAO.Consequently,the integrated power supply can satisfy the requirements of MAO constant current mode. |