电子束直接熔化技术中的粉末状态分析

Analysis of metal powder deposition in electron beam direct melting technology

在电子束直接熔化金属粉末技术中,为了避免真空室抽气瞬间的气流和电子束对金属粉末的作用力改变粉末的堆放状态,建立了金属粉末受力模型,并对金属粉末的受力进行计算和分析。理论分析与实验结果表明,在抽气口位置粉末容易被气流抽走,工作台不能与抽气口在同一水平高度。0.5mA以上的电子束束流引起的压力会推开气雾化不锈钢粉末,该现象的主要解决途径为降低电子束束流、提高粉末致密度和选用摩擦因数大的金属粉末。此外,利用电子束对金属粉末预热,提高其相互间的粘结力也是解决方法之一。

The airflow caused by the vacuum pump and the impact of the electron beam disrupt the metal powder deposited during electron beam direct melting technology. Experimental and theoretical analyses of the powder deposition process showed that powders must be deposited far from vacuum pump inlet. Furthermore, electron beam current strengths exceeding 0. 5 mA tend to push the atomized stainless steel particles away from the surface. The problems can be resolved by limiting the electron beam current strength, improving the powder deposition density, choosing the appropriate powder shape, and preheating the powder to enhance the metal powder＇s viscosity.