精密鑄造陶殼模之薄殼快乾研究

Study on the Thinning and Rapid Drying Ceramic Shell Mold for Investment Casting Process

紀孟宏(M. H. Ji) ； 蕭煜成(Y. C. Hsiao) ； 楊國和(Koho Yang) ； 錢士立(S. L. Chian) ； 葉金城(J. C. Ye)

《鑄造工程學刊》 38卷4期 (2012/12) Pp. 1-12

https://doi.org/10.29809/JTFS.201212.0001

摘要

本研究主要在精密鑄造陶殼模製程的面漿及背漿中，探討不同矽膠液對泥漿性能及陶殼模性能之影響。熔融石英因具低密度、低熱膨脹係數、低比熱、比重輕等特性，以及近年來鋯粉及鋯砂物價飆漲，故於面漿及面砂以熔融石英粉及熔融石英砂取代鋯粉及鋯砂，此外亦探討取代後對泥漿性能及陶殼模性能之影響。實驗有三種組合：(1)Type 1，矽膠液A+鋯粉+鋯砂；(2) Type 2，矽膠液B+鋯粉+鋯砂；(3) Type 3，矽膠液B+熔融石英粉+熔融石英砂，背層耐火材料則均採用馬來粉及馬來砂。針對泥漿性能之影響，主要探討泥漿的黏度、流變性、pH值、沉降速率、水分散失速率等進行量測及觀察；針對陶殼模性能之影響，陶殼模層數為四層半，主要探討陶殼模的重量、厚度、乾燥時間、破斷強度、高溫透氣度、濕度、持溫時間等實驗條件進行量測及分析。最後再實際進行鑄件澆鑄。實驗結果顯示：比較Type 1、Type 2及Type 3三種組合，在泥漿性能方面：Type 2及Type3相較於Type 1泥漿的黏度及流變性有減緩上升趨勢；泥漿pH值的影響不大，但pH值較高可減緩泥漿膠化；Type 3可減緩泥漿沉降速率；泥漿水分散失速率差異不大，但泥漿水分散失量較多。在陶殼模性能方面：Type 2及Type 3相較於Type 1減輕陶殼模重量、減少陶殼模厚度、縮短陶殼模乾燥時間；提高陶殼模濕態破斷強度，降低高溫及殘留破斷強度；提高高溫透氣度；持溫時間對破斷強度影響並不大；但高溫透氣度則隨持溫時間的增加略微上升；降低環境濕度可減少陶殼模乾燥時間。在陶殼模澆鑄方面，使用Type 2組合澆鑄316L不銹鋼，陶殼模強度可承受高溫金屬液之衝擊。

關鍵字

精密鑄造 ； 泥漿 ； 陶殼模 ； 熔融石英 ； 薄殼快乾 ； 矽膠液

並列摘要

The effects of different water based colloidal silica binders on the properties of primary and backup slurries and ceramic shell mold have been studied. In addition, the fused silica, due to its low density, low thermal expansion coefficient, low specific heat and some other characteristics; and also, the price of zircon has increased sharply, and has soared to sky-high level for the past ten years, therefore, is considered as a substitution material to replace the zircon for slurry preparation. Besides, after the fused silica substitution, its effects on the properties of slurries and ceramic shell mold have been studied, too.There were three various combinations in this study, namely: (1) Type 1, water based colloidal silica A + zircon flour + zircon sand, (2) Type 2, water based colloidal silica B + zircon flour + zircon sand, and (3) Type 3, water based colloidal silica B + fused silica flour + fused silica sand; both mullite flour and grain were used as the backup refractories. As to the effects on the slurry properties, the viscosity, rheological properties, pH value, sedimentation rate and water loss rate were measured and investigated. As to the effects on the ceramic shell mold properties, the four and a half layers ceramic shell molds were applied, and were principally studied on the weight, thickness, drying time, MOR (green strength, hot strength and fired strength), permeability, humidity, and holding time for sintering. Finally, the practical metal casting experiment was conducted.Regarding to the three combinations the results showed: (1) On the slurry properties, compared with Type 3, the upward tendency of the viscosity and rheological properties of Type 1 and Type 2 were slowed down; and there were no obvious changes on the pH value variation, but the higher pH would prolong the gelation of the slurry; the sedimentation rate of Type 3 could be reduced; though the difference of the water loss rate was not much, the amount of water loss was larger. (2) On the ceramic shell mold properties, compared with Type 1, both Type 2 and Type 3 have a lighter, thinner and shorter drying time. Meanwhile, Type 2 and Type 3 also have a higher green strength, lower hot and fired strength, and a higher hot permeability. Holding time for sintering shown no evident variation for MOR, but might slightly increase the high temperature permeability. Lower humidity could reduce the drying time for ceramic shell mold. (3) On the practical metal casting experiment, the Type 2 ceramic shell mold strength could withstand the impact of the high temperature 316L stainless steel liquid metal and without the molten metal leakage happened.

並列關鍵字

Investment casting ； slurry ； Ceramic shell mold ； Fused silica ； Colloidal silica ； Properties