STUDY ON THE ACTIVATED SINTERING OF MECHANICALLY PROCESSED TUNGSTEN POWDERS
There are some tungsten powders that exhibit a poor sinterability. A part of them are produced by chemical recovery of tungsten from metallic waste. The goal of the present work is to improve sinterability of such tungsten powders, applying them a short mechanical process in a planetary ball mill. Experiments to determine the effects of the milling duration on the change of the powder properties (density, specific surface, average particle size, particle shape, micro hardness) have been made. Changes in the sinterability of mechanical processed tungsten powders were followed on cylindrical samples pressed in a die with different compaction pressures (50-125 MPa), and successively sintered in the same conditions (T=1200 0C for 1 h, hydrogen atmosphere). Apparent density, compressive strength and the ratio of compressive strengths to apparent density after sintering were selected as estimating parameters for sinterability depending on the milling time of tungsten powders.
Key words: Tungsten heavy alloy, liquid phase sintering, activated sintering
W. Schatt, W. A. Kaysser, S. Rolle, A. Sibilla, E. Friedrich, G. Petzow, Powd. Met. Int., Vol.19, (1987),p. 14-18.
F.V.Lenel, Powder Metallurgy, Principles and Applications, MPIF, Princeton, New-York, (1980), p.589.
S.G.Caldwell, Microhardness. Variations in Tungsten-Based Heavy Alloys as a Function of Composition and Processing Variables, Progress in PM, 1985, Annual Conf. Proc., Vol. 41, MPIF-APMI, (1985), p. 123-138.
R. Muresan, Ph D., Thessis, Technical University of Cluj-Napoca, (2000), p. 124.
- There are currently no refbacks.