製備奈米氫氧化鈣溶液加固古交趾陶胎體之研究

A Study of Consolidating Ancient Koji Pottery Body Using Colloidal Nano-Calcium Hydroxide Solution

臺灣傳統廟宇與宅第建築的低溫陶作裝飾慣稱為交趾陶，其融會了形塑、製釉與窯燒等工藝技術，具有形塑生動的造型、鮮明的釉彩，以及蘊含歷史典故或吉祥寓意的題材等特色，反映著臺灣早期常民生活與宗教信仰的內涵，是研究過去臺灣工藝與文化發展的歷史證物。因為交趾陶是以低溫燒製，所以胎體結構富有孔隙，再加上現存古交趾陶的保存多為現地保存，長年承受風吹日曬雨淋，時時刻刻都面對老化與風化的威脅，所以研究如何保護戶外現地保存的古交趾陶是迫切需要的。本研究即嘗試以奈米氫氧化鈣加固模擬的古交趾陶胎體。奈米氫氧化鈣是以氯化鈣為原料，異丙醇做為溶劑並於氮氣環境下加熱水解，經過離心與超音波震盪清洗得到粒徑80~150nm之膠體溶液。奈米氫氧化鈣則以粉末X光繞射，拉曼光譜，穿透式電子顯微鏡進行觀察鑑定。加固用的膠體溶液，以真空乾燥濃縮使氫氧化鈣濃度為5g/L。將此溶液反覆塗佈於交趾陶胎體試片，再以濕熱的二氧化碳氣氛(濕度95%，溫度50℃)使其中性化，養護後之晶體結構變化，使用拉曼光譜分析之結果顯示，氫氧化鈣並未與胎體中之二氧化矽反應成矽酸鈣，僅轉並為碳酸鈣，推論加固機制為物理性加固。比較滲透加固後之孔隙率、吸水率約降低2%，彎曲強度增加7%，證明氫氧化鈣的加固對於胎體的孔隙率、吸水率與彎曲強度有正面效應。

Koji pottery, a kind of low temperature color glazed pottery, is used in decorative architectural motifs on Taiwan’s traditional temples and residential buildings. Combined with the molding, glaze making and kiln-firing techniques, Koji pottery is shaped into vivid models with resplendent color and preserves the historical allusions and auspicious meanings reflecting life and religion during the early period of Taiwan. Moreover, Koji pottery bears witness to the development of craft techniques and culture. However, the lowfiring process leaves the Koji pottery fabric porous. Furthermore, most of the ancient Koji pottery works are preserved in situ and so they are always threatened by aging and weathering after being exposed to the elements for many years. For these reasons, it is urgent to protect Koji pottery works. This research strives to consolidate ancient Koji pottery using nano-calcium hydroxide. Nano-calcium hydroxide uses CaCl2 as a starting material and 2-propanol as a solvent. First, CaCl2 was dissolved in hot water flushed with nitrogen. This was then added to 2-propanol and the solid separated by centrifugation and ultrasonication. Nanocalcium hydroxide, as a colloidal solution was produced with a particle size 80~150nm. Nano-calcium hydroxide was analysed by powder XRD, Raman spectroscopy and TEM. Secondly, a vacuum drying oven was employed to condense the colloidal solution to give a calcium hydroxide concentration of 5g/L. The colloidal solution was repeatedly applied to Koji pottery samples and was neutralized by carbonating it in a carbon dioxide atmosphere (humidity 95%, temperature 50℃). Finally, after the curing process, Raman spectroscopy was used to characterize the in crystal structure. The results show that calcium hydroxide did not interact with SiO2 to turn into calcium silicate; instead it formed CaCO3 and the ceramic body underwent physical consolidation. The porosity and water absorption were decreased by 2% and flexural strength was increased by 7% after consolidation. This research proves that consolidation by nano-calcium hydroxide is effective in reducing porosity and water absorption and reinforcing flexural strength.