富含氧化釔陶瓷殼模之低溫燒成研究

Abstract

本研究致力於富含氧化釔陶瓷殼模之低溫燒成研究。由於氧化釔價格昂貴 且不易燒結(至少在1600oC以上)，因此嚐試加入不同的耐火粉末來改善此 情形。除了成分之尋求外，對於殼模製程:如漿體組成及流變性質，乾燥 條件的控制，脫蠟之步驟，和燒結之溫度控制，都予以探討與最佳化。其 中最佳漿體要求高固含量，穩定而適當的黏度狀態，和剪切薄化行為。我 們除了加入耐火粉末，另外並加入氧化釔膠液作黏結劑，和甲基纖維素作 高分子分散助劑，並依粉末安定與否加入緩衝溶液，而緩衝溶液以醋酸和 醋酸鈉水溶液所配製，可遠離陶瓷粉末之等電點而使漿體保存時間延長。 由本實驗最後製作出之二種殼模，第一種殼模經過1400.degree，10小時 燒結，其強度約為950psi，密度為2.7。第二種殼模經過1400.degree.，5 小時燒結，其強度約為1000 psi，密度為3.5。兩者皆符合殼模的要求。 The purpose of this study is to investigate the low temperature sintered yttrium oxide-riched ceramic shell mold. Because of the expensive cost and high sintering temperature (above 1600.DEGREE.), we try to add another refractory powder to improve them. In addition, the manfacturing process of the ceramic shell molds : about the composition of slurry and its rheology behavior , the control of the drying, the steps of losing wax, and the temperature control of sintering, we would discuss and optimize them. The optimal slurry for making ceramic shell molds demands high solid content, stable and sutiable viscosity state, and shear thining behavior.We add the yttrium oxide sols as the binder, methylcellouse as the polymer dispersion agent and add the buffer solution if the powder is unstable. The buffer solution is composed of acetic acid and sodium acetate, it can let the solution far from isoelectric point and keep stable longer. In our experiment the final products: there are two kinds of ceramic shell molds. The first molds sintered at 1400.degree. for 10 hours, and the strength is 950psi. The second molds sintered at 1400.degree. for 5 hours, and the strength is 1000psi. The density are 2.7and 3.5, respectly . Both of specimens are satified with the properties of shell molds.