液相烧结碳化硅陶瓷腐蚀行为的显微观察

研究了AlN-R2O3（稀土氧化物）液相烧结碳化硅陶瓷在HF、HCl、NaOH、KOH、K3Fe（CN）6等单独或混合液中的腐蚀行为。检测了试样腐蚀前后的失重,用扫描电镜观察了试样腐蚀前后的显微形貌。结果表明,室温或煮沸条件下试样在HF、HCl、NaOH、KOH强酸、强碱中主要表现为晶隙液相腐蚀,晶隙间的玻璃相被腐蚀掉后留下形似岛屿的SiC晶粒,晶粒紧密相接的晶界未受侵蚀。试样在酸中比在碱中的腐蚀程度重。室温下腐蚀进程缓慢,煮沸后腐蚀迅速;在K3Fe（CN）6液中基本不受腐蚀;而在K3Fe（CN）6与KOH的混合水溶液中主要以晶界腐蚀为主,该混合液能很好地将晶体边缘轮廓腐蚀出来。在强酸中试样失重先快后慢;在强碱中试样不失重或失重轻微。

Microstructure observation on corrosion behavior of liquid phase sintered silicon carbide ceramics

The corrosion behavior of LPS (liquid phase sintered) silicon carbide with AlN-R_2O_3(Y_2O_3+La_2O_3) as sintering additives were investigated. The samples were tested by putting into HF, HCl, NaOH, KOH, K_3Fe(CN)_6, etc. or mixed solution of them. The weight loss of samples after corrosion are measured. The SEM photo of the experimental specimen before and after corrosion are compared. The result shows that under both room and boiling temperature, the corrosion of LPS-SiC in HF, or in HCl, in NaOH,in KOH, ...