Purification Of Nickel Metal By Electron Beam Melting

Nickel is one of the important strategic reserves resource, high purity of nickel have high shaping, high temperature resistance, corrosion resistance and good mechanical properties, its status and role in the national economy and aerospace increasingly prominent, scientific researchers pay unprecedented attention to it. Standard High Purity Nickel is divided into four grades of different purity, each grade has its application, and the higher the purity of nickel is, its alternative is weaker. There are many methods of the production of the high-purity nickel, such as the MCLE method, the reduction of nickel oxide method, the electrolytic refining method and so on.But because of the high cost and large pre-construction costs, scientific researchers have been exploring more efficient method of production of high purity nickel. Because of its high degree of vacuum, high energy density, easy to automatic control, purification by the electron beam melting is widely used in the purification of high-purity of the metalsand high purity of the silicon, purification of high-purity Ta, Ni, Ir, W, Mo, Hfby EBMhave been practical applied. This article use EBM to remove impurity by evaporation and directional solidification. The conclusion are as follows:(1) By reduce the power slower after EBM, the grain of the ingot is more coarse than the ingot getting by reduce the power immediately. The grain go through the bottom to the top;(2) When the power is the same, the content of the impurities is reduced in logarithmic trend as the time increase, but at the same time, the mass loss linear increase.The larger the melting power is, the faster the volatile impurities remove. And EBMhas obvious effect for As, Cu, P element, their removal reactions are all first order reaction and the evaporation capacity order is P> Cu> As, but it has no significant effect for impurity elements Pb and Co;(3) Considering of the mass loss and of removing rate of the impurities, the best parameter is 12kW for 15min, theoretically the purity of the nickel is improve to 99.96%. In fact, the purity is to 99.94%, and the removal percentage of As element is 78.7%, the Cu is 80.6%;(4) By reduce the power slower to make the nickel ingot to directional solidification, it has a obvious effect for As, Cu, Pb and Co. these impurities are gather in the bottom of the ingot, the removal percentage of Pb element is 55.9%, Co is 24.5%.