Effect of entrapped inert gas on pore filling during liquid phase sintering

The effect of an inert gas entrapped in isolated pores on liquid flow into them during liquid phase sintering has been studied. An analysis of the balance between the capillary pressure of the liquid menisci and the gas pressure shows that the entrapped gas delays the pore filling and produces bubbles. If the gas pressure exceeds a critical level, the pores remain intact and the critical point for their filling will never be reached. These predictions are confirmed by experimental observations on large spherical pores produced artificially in an Fe-Cu alloy. Argon gas is trapped in the pore by first sintering in Ar-H₂ mixture gas and then in H₂ after the isolated pores are formed. The entrapped inert gas of even low pressure is thus shown to cause a substantial porosity in liquid phase sintered specimens. Formerly a Doctoral Student at the Korea Advanced Institute of Science and Technology.