IMPROVEMENT OF ENVIRONMENTAL DURABILITY AND STRENGTH OF SIALON CERAMICS BY TAILORING THE GRAIN-BOUNDARY PHASE DUE TO SOLID-SOLUTION NATURE

通过调整固溶性质的晶界相来提高 Sialon 陶瓷的环境耐久性和强度

• 批准号: 09650736
• 负责人: YOSHIO Tetsuo
• 金额: $ 2.18万
• 依托单位: OKAYAMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650736/
• 关键词: sialon ceramics; solid solution; aqueous corrosion; forms of corrosion; uniform corrosion; pitting corrosion; corrosion resistance; strength degradation; 耐食性

Hydrothermal corrosion and strength degradation of Si_3N_4-based ceramics has been investigated using an autoclave method in order to assure the tailoring effect of grain-boundary phase on corrosion resistance of alpha-sialon. The hydrothermal corrosion products in sialon ceramics can be removed easily from the substrate in an ultrasonic waterbath. SEM micrographs for corroded substrate after removal of corrosion products revealed the nature of forms of corrosion for each ceramics In Si_3N_4 ceramics, corrsion pits were clearly observed. In contrast, the corroded substrate of alpha-sialon revealed the surface with no identifiable corrosion pits, which could be designated as uniform corrosion.Fracture strength degradation as a function of exposure time for these sialon ceramics is showed a rapid decrease in fracture strength occured in the early stage of corrosion, and then was almost cnstant up to 10 days. However, the degree of strength degradation was different between the uniform corrosion in alpha-sialon and the pitting corrosion in Si_3N_4. Although the strength decrease after extended exposure in the latter was 40%, thatin the firmer was only 15%. Formation of corrosion pits may explain the larger extent of strength reduction. Thus, it has been found that corrosion resistance and strength degradation in alpha-sialon are superior to other types of sialon due to the solid-solution nature.

采用高压釜法研究了Si_3N_4基陶瓷的水热腐蚀和强度退化，以确定晶界相对α-sialon耐腐蚀性能的剪裁作用。在超声波水浴中，sialon陶瓷中的水热腐蚀产物可以很容易地从基体上去除。去除腐蚀产物后的SEM照片揭示了各陶瓷腐蚀形态的本质。在Si_3N_4陶瓷中，腐蚀坑清晰可见。而α-sialon陶瓷腐蚀后的表面没有明显的腐蚀坑，属于均匀腐蚀，其断裂强度随腐蚀时间的变化曲线表明，在腐蚀初期，断裂强度迅速下降，到10 d时，断裂强度基本保持不变。而α-sialon中的均匀腐蚀和Si_3N_4中的点蚀导致的强度下降程度不同。尽管后者在长期暴露后强度下降了40%，但更坚固的仅为15%。腐蚀坑的形成可以解释强度降低的较大程度。因此，已经发现，由于固溶体性质，α-赛隆的耐腐蚀性和强度退化上级其它类型的赛隆。

项目成果

小田耕平: "酸化物セラミックスの塩素・塩化水素ガスによる高温腐食" 材料と環境. 46・11. 736-738 (1997)

小田晃平：“氯和氯化氢气体对氧化物陶瓷的高温腐蚀”材料与环境46・11（1997）。

小田耕平: "Hydrothermal Corrosion of Alumina Ceramics" J.Am.Ceram.Soc.80・12. 3233-3236 (1997)

小田晃平：“氧化铝陶瓷的水热腐蚀”J.Am.Ceram.Soc.80・12（1997）。

E.Opila: "The Oxidation of ALN in Dry and Wet Oxygen" Proc.of The High Temperature Corrosion and Materials Chemistry. Vol.98-9. 430-437 (1998)

E.Opila：“干氧和湿氧中 ALN 的氧化”《高温腐蚀与材料化学》论文集。

E.Opila: "The Oxidation of AlN in Dry and Wet Oxygen" Proc.of High Temperature Corrosion and Materials Chemistry. 98・9. 430-437 (1998)

E. Opila：“AlN 在干氧和湿氧中的氧化”Proc. 高温腐蚀和材料化学 98・9 (1998)。