Research On Repair Of Al-Ga Alloy By Electro-spark Deposition

Al-Ga alloy is a degradable aluminum alloy with both structure and function.It can complete the degradation requirements at a predictable rate under different temperatures,different media and different pressures.When it is cast into a fracturing ball,it will produce a surface defects become unqualified parts.In order to save costs and improve production efficiency,the defects need to be repaired.The electro-spark deposition(ESD)technology has the characteristics of small heat input,strong flexibility,high bonding strength,low price,simple operation,and can be used for on-site repair,etc.It will not affect the substrate,and shows great advantages in the processing and repair of aluminum alloys.Therefore,this paper uses ESD technology to repair the Al-Ga casting alloy,and researches and analyzes the hardness,roughness,and degradability of the repair layer under the optimized process.In addition,the 3.5 inches fracturing ball was repaired based on the above research.The following results are obtained:(1)The electro-spark deposition process was studied through two aspects of electrical parameters and physical parameters.In terms of electrical parameters,the influence of voltage,capacitance and frequency on the repair layer was mainly studied.The study found that voltage and capacitance mainly affect the quality of the repair layer through heat input.Too low or too high heat input will adversely affect the repair layer.The frequency mainly affects the surface roughness and thickness of the repair layer.The smaller the surface roughness of the layer,the greater the thickness of the repair layer.In terms of physical parameters,the effects of pressure and protective gas on the quality of the repair layer were mainly studied.It was found that when a small pressure is applied during the deposition process,a better quality repair layer can be obtained.When argon is used as the protective gas,the protective effect is better than that of nitrogen,and a repair layer with a smooth surface can be obtained.Through orthogonal design experiments and optimization experiments,the best process for repairing Al-Ga alloy was selected,namely voltage 90 V,capacitance 210 ?F,frequency 5000 Hz.(2)Under the optimal process parameters,the microstructure and properties of the repair layer were tested.From the results of the surface scan of the repair layer,it can be seen that the repair layer has a dense structure and uniform element distribution,which can reduce component segregation and improve the performance of the repair layer.Due to the extremely fast cooling rate in the ESD process,the hardness of the repair layer has increased,from 85 Hv to 95 Hv.The maximum surface roughness of the repair layer is 15 ?m,which can meet the requirements for use.Under the optimal process,the degradation rate of the repair layer is closest to that of the substrate.(3)The application of ESD to repair arc surface is briefly explained.Based on the optimized process,the surface defects of the 3.5 inches cast Al-Ga alloy ball were successfully repaired,and all the properties reached the engineering indicators.