Compaction is dependent on the speed at which water is removed from the starting powder mixture. If there is no path for the water retreat, it remains in the pores and prevents densification [70].The final relative density in the HHP depends on processing temperature, pressure, time and amount of water used [70]. Fig. 4(a) provides the schematic drawing of the HHP equipment, while Fig. 4(b) shows the autoclave details [53,73].