Effect of Hot Isostatic Pressing on Reaction‐Bonded Silicon Nitride

Reaction-bonded silicon nitride was isostatically hot-pressed under 138 MPa for 2 h at 1850°, 1950°, or 2050°C. Nearly theoretically dense specimens resulted. The room-temperature flexural strength more than doubled, but the 1200°C flexural strength increased significantly only after pressing at 2050°C.f. ∼35% improvement). An amorphous phase introduced by hot isostatic pressing accounts in part for these results.