硅电极电火花表面改性的研究

以工业纯硅为电极,通过电火花放电对试样进行表面改性处理.电火花设备型号为EDM7125,工作液为普通煤油,电极材料含硅99.6%,工件材料为45钢和球铁.采用扫描电镜及金相显微镜对试样表面形态进行了研究,对试样表面进行了能谱分析,对试样进行了耐蚀及表层结合强度等试验.结果表明:试样加工后表面形成一层含硅超过16%的合金层.电火花加工球铁石墨基本未脱落,但石墨周围易产生或扩展显微裂纹.高硅层结合强度非常高,进行永久变形时,无剥离和裂纹产生.而且,经电火花加工过的试样耐蚀性得到极大提高.另外,电火花加工,当参数合理时,可达到粉末混入加工的目的,试样可获得好的表面质量.

Surface Modification by Electrical Discharge Machining using Industrial Si as Tool Electrode

The surface modification by electrical discharge machining(EDM)using Si as tool electrode for 45 steel and nodular iron was presented.The experimental equipment is EDM7125,and common kerosene is used as dielectric fluid.The tool electrode material is industrial Si with purity 99.6%.The microstructure of the workpieces surface was analyzed by OM and SEM.Furthermore,quantitative analysis of element content has been carried out by EDS.The corrosion resistance and the cohesion strength of the modified layer were also studied.Results of experiments show that the modified layer with high Si content,nearly reaches 16%,occurs on the EDMed workpieces surface.In addition,on the whole,graphite doesn't be flushed away.But one feature found on EDMed surfaces is a little of cracks,especially cracks are easy to initiating and propagating at graphite/matrix interface.The modified layer has high bonding strength,and disbanding and crack doesn't occur after permanent distortion.And the sample has better corrosion resistance.However,a large number of Si powders occur between the two polarities when utilizing Si as tool electrode,especially positive polarity machining.Besides,appropriate machining parameters will obtain better surface quality.