RATE-CONTROLLED SINTERING OF ULTRAFINE NICKEL POWDER

Results ofan experimental investigation on rate-controlled sintering (RCS) of ultrafine nickel powder are considered. Optimization of the temperature-time path for sintering allowed a specific density level not less than 0.99 to be achieved, and a grain size less then 100 nm to be maintained (starting grain size was equal 25 nm). An analogous result cannot be attained by constant rate of heating (CRH) schedules. Comparison of the kinetics and structural development of both RCS and CRH processes shows that the RCS method gives much more homogeneous and uniform pore shrinkage, without intensive recrystallization, up to a high density level.