Containing ¦Â-sialon, Si <sub> 3 </ Sub> N <sub> 4 </ Sub> Al <sub> 2 </ Sub> O <sub> 3 </ Sub>-based Long Nozzle, The Material Properties Of

The properties of the currently used alumina-carbon long nozzle, whose graphite were partly or all in place of non-oxides material (β-Sialon and Si₃N₄), have been studied in this work. Totally eight chapters are included in this thesis. Among them, study on the alumina-carbon long nozzle with non-oxides (β-Sialon and Si₃N₄) is shown from the fourth to seventh chapters. The non-oxides (β-Sialon and Si₃N₄) is added into alumina-carbon long nozzle and their properties (including physical properties in room temperature, hot modulus of rupture (HMOR), thermal shock resistance (TSR) and oxidation resistance) have been studied. The results indicate as follows:With increae of β-Sialon, apparent porosity of specimens after heat treating at 930℃× 3h was increased, bulk density was decreased, modulus of rupture was decreased.β-Sialon has negative effects on HMOR. The reason is apparent porosity gradually increases. MOR-T curves of the specimens with β-Sialon addition were studied. Results showed that MOR of specimens initially increases and then decreases, and the temperature of highest value of MOR is 800℃-1000℃. The specimens with β-Sialon addition have good thermal shock resistance. The residual strength and residual strength ratio of the specimens with β-Sialon addition 14% after cooling by water for three and five times at 1100℃ reach the highest value. The specimens with β-Sialon addition 7% show better oxidation resistance at 1300℃.With increase of Si₃N₄and Al, apparent porosity of specimens after heat treating at 1450 ℃ × 3h was increased, bulk density was changed slightly, modulus of rupture was increased.With addition of Si₃N₄ and Al, the specimens have a marked improvement in the HMOR. The maximum MOR value is obtained in the specimens with 3% Si₃N₄ at 1400℃. Based on the EDAX and XRD analysis, the reason of improvements in HMOR depend on Sialon synthesized by the in-situ reaction of Si₃N₄ and Al and Al₂O₃, which improve the solid-solid combination rate of material and is beneficial to high temperature properties. The specimens with Si₃N₄ addition have good thermal shock resistance. The residual strength and residual strength ratio of the specimens with Si₃N₄ addition 6% after cooling by water for three and five...