An experimental study of the sintering kinetics of tungsten powder has been made in the temperature range 1100-1600°C. The effects of particle size, compacting pressure, sintering atmosphere, sintering temperature and sintering time upon the rate of sintering were examined.
Isothermal changes in the length, volume and density of the compacts were measured and the results were evaluated in terms of the usual degree of sintering parameter, δ , a new volume parameter, V, and by the linear shrinkage method. Of these parameters, it was found that the most reliable information was obtained by use of the volume parameter.
It was found that the activation energy for sintering tungsten powder was 102 ± 2 kcal/mole which is consistent with a mechanism which involves grain boundary diffusion. The increase in fine particle size of the tungsten powder increases the sintering rate.
The kinetics of isothermal grain growth during sintering were also examined in the temperature range 1100 to 1650°C. No grain growth was observed at temperatures below 1400°C,however, above this temperature the grain diameter increased at a rate proportional to sintering time, t 1/3. The activation energy of 94 kcal/mole obtained for this process is in reasonable agreement with that derived for densification.
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