生陶瓷體內高分子黏合劑熱解程序之最佳化控制

Optimal control of the binder burnout in a LTCC substract

邱吉晟(Chiu Chi Chong)

指導教授 ： 廖朝光

元智大學/工程學院/化學工程與材料科學學系/碩士(2004年)

摘要

本研究探討以最佳化的方法找尋陶瓷胚體內之高分子黏合劑燒除製程的最佳化加熱速率控制，利用高分子黏合劑的熱裂解反應動力與陶瓷胚體內黏合劑受熱裂解產生氣體產物流出胚體外的質傳現象，建立三維空間中之氣體輸送模型，以有限差分法 ( finite difference method ) 模擬黏合劑在胚體內熱裂解產生氣體的氣體壓力分佈情形，並以最佳化之方法找尋在不使胚體產生缺陷的最大壓力下之最佳化加熱速率操作條件。以工業上常用之PVB與玻璃陶瓷的混合重量百分比為30%PVB與70%玻璃陶瓷的組成，簡稱P30C70，在不同氣體氣氛下的熱解反應動力參數，模擬該組成在不同加熱速率下於胚體內的氣體壓力分佈，由模擬結果顯示，使用較大的加熱速率時，在胚體中心點與邊緣處所受應力與壓力降會增加。以P30C70的樣品發現，PVB在空氣會比在氮氣時，提早開始熱解，但反應完畢所需時間比在氮氣時更長。使用相同加熱速率時，PVB在氮氣下熱解所產生之氣體壓力最大值比在空氣中更大。由最適化結果顯示，以最佳化加熱速率為操作條件，可在不使胚體產生缺陷的最大壓力下，減少黏合劑燒除製程所需時間，達到提高良率與節省製程時間成本的目的。

關鍵字

聚乙烯醇縮丁醛 ； 高分子熱解動力 ； 最佳化控制 ； 有限差分法

並列摘要

The control strategies of optimal heating rates were studied for the burnout process of polymer binders inside a 3-D ceramic body in nitrogen and air atmospheres. The polymer binder can be degraded as gaseous products in higher temperatures and diffuse into the ceramic surface. The burnout process model was described by the kinetics of polymer degradation and the mass transport phenonemum. A finite difference method was used to simulate the pressure distribution caused by the transport of the gaseous products. The pressure distribution can affect the generation of the ceramic defects and have to be controlled by the heating conditions. The computational results show that higher heating rates can generate larger pressure at the body center point and pressure drop at the edge of the surface. In addition, the maximum pressure generated at the body center was higher for operating in nitrogen than in air. However, the burnout period is longer for in an air case than in a nitrogen case. The optimal control of the heating rates was discussed in both cases using the algorithm developed in this work.

並列關鍵字

poly(vinyl butyral) ； kinetics of polymer degradation ； optimal control ； finite difference method

參考文獻

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