立方晶格金属扫描电子束抛光处理下表面建模与试验研究

Surface Modeling and Experimental Research of Cubic Lattice Metal Polished by Scanning Electron Beam

目的探究扫描电子束作用下立方晶格金属表面凸起的温度随扫描时间的变化规律。方法以铣削加工后的立方晶格金属试样为研究对象,通过数值模拟的方法剖析表面凸起形状和一维热传导模型,采用理论和抛光试验相结合的方法分析电子束能量密度、电子束作用时间与温度之间的函数关系,并通过仿真软件建立不同材料属性、凸起形状影响下的温升曲线。结果铣削表面的凸起形状可简化为圆锥形、半椭圆形和半球形,表面凸起的温度受到电子束能量密度、电子束作用时间以及起伏形貌参数比三个因素影响。凸起温升速率与材料导热性能正相关,当起伏的温度高于熔点200 K时,45钢与AZ91D镁合金的表面粗糙度均有所降低。起伏形状的温升速率与形状比正相关,且圆锥形凸起经三角函数拟合后的起伏温升曲线和形状比数值相似度较高。结论扫描电子束抛光处理立方晶格金属表面时,通过建立凸起的温度变化曲线,可指导电子束工艺参数选取,预测表面形貌变化。

This paper aims to determine the variation between the temperature on the surface protrusion of cubic lattice metal polished by scanning electron beam and the scanning time.The cubic lattice metal sample after milling was chosen as the research object,the surface protrusion shape and the one-dimensional heat conduction model were analyzed by numerical simulation,the functional relations between the temperature and the electron beam energy density or the electron beam action time were studied by combining theory and polishing test,and the temperature rise curves under the influence of different material properties and protrusion shapes were established through simulation software.The protrusion shape of the milling surface can be simplified into conical,semi-elliptical and hemispherical shapes;the temperature on the surface protrusion was affected by three factors:electron beam energy density,electron beam action time,and undulating topography parameter ratio;the protrusion temperature rise rate is positively correlated with the heat conductivity of materials.When the fluctuating temperature is 200 K higher than the melting point,the surface roughness of 45 steel and AZ91D magnesium alloy is reduced;the temperature rise rate of the fluctuating shape is positively related to the shape ratio,and the temperature rise curve and the shape ratio value of the conical protrusion is similar to those fit by.trigonometric function.When the cubic lattice metal surface is polished by scanning electron beam,by establishing the protrusion temperature change curve,the selection of electron beam process parameters can be guided to predict its surface topography changes.