1995 Volume 81 Issue 11 Pages 1061-1066
In powder making process such as EBRD(Electron Beam Rotating Process), it is important to solve a problem that some of the molten metal droplets partially solidify and remain on the rotating disk before disintegration.
The solidification phenomena of Ti-6Al-4V alloy droplets on the rotating disk, and the effect of various factors on the solidified amount were experimentally studied.
The results obtained were as follows.
(1) Molten metal droplets partially solidified on the rotating disk, and the solidified shell on the disk is necessary for better atomization.
(2) In the case of a water-cooled copper disk, the heat flux qd to the disk is 28.6 cal/cm2sec and the solidified amount, η(%) is expressed as
η(%)=-(CpΔTW-qdA+qe)/ΔHW), (Cp ; specific heat, ΔT ; super heat, W ; rate of melt supply, A ; disk surface area, qe ; heat input from external heat source, ΔH ; latent heat)
Heat input on the disk reduces the solidified amount. For example, 5kW is necessary for preventing the solidification at the melt supply of 3kg/min and the disk diameter of 80mm.
(3) In the case of disk made of heat insulating material such as graphite or Ti-6Al-4V alloy, it is difficult to maintain the continuous atomization because of the lack of deformation strength of rotating disk or disk holder.