Elimination of large Pores During Gas‐Pressure Sintering of β′‐Sialon

Abstract

The effect of N 2 ‐gas pressure on the liquid filling of large pores (20 to 120 μm in diameter) is studied in sintered β′‐sialon ( z = 1). The initially sintered sialon with large pores is sintered again and infitrated by a liquid (41A1 2 O 3 ‐41Y 2 O 3 ‐14Si 3 Y 4 ‐4AIN (wt%)) at 17800°C for various times under 0.1‐, 0.3‐, and 0.5‐MPa (1‐, 3‐, and 5‐atm) N 2 . The liquid fills large interconnected pores; the size of the pores filled with liquid increases with N 2 ‐gas pressure and time. In some liquid pockets, gas bubbles are formed and subsequently disappear during prolonged sintering treatment. The liquid‐filling be havior with sintering pressure and time is explained by gas pressure in the pore and thermal decomposition of the material. The benefit of gas‐pressure sintering for the elimination of large pores is assessed.