Effect of particle size on compressibility and sintering of titanium powders

In this research, the effects of the powder particle size on the compaction and sintering of Hydride–Dehydride titanium powders are investigated. Commercially pure titanium powders with three different size ranges were utilized. Compaction was accomplished under applied pressures of 200 to 650 MPa. Sintering was carried out at 1100 to 1400 ºC temperatures. The compressibility behavior of the differently-sized powders was studied by measuring the density of the green compacts. The microstructure of the produced compacts was studied using scanning electron microscopy. Results showed that the small powders have the least compressibility. The compressibility data was analyzed and studied by common compaction equations. The modified Heckel equation showed the best correspondence. In addition, measuring the density of the sintered compacts showed that the small powders had the highest sinterability. The highest amount of sintered density (98% theoretical) was attained for the small powders compacted under 650 MPa and sintered at 1400 ºC. However, the sintering temperature of 1200 ºC was recognized as the most appropriate temperature for the middle and large-sized titanium powders. The results of the hardness tests showed that the appropriate mechanical properties could be attained for commercially pure titanium powder compacts by vacuum sintering accomplished at the optimum sintering circumstances.