陶瓷雷射膠化法製程改良

Improvement of Ceramic Laser Gelling

吳俊宏(Cheng-Hung Wu)

指導教授 ： 湯華興

國立臺北科技大學/機電學院/製造科技研究所/碩士(2010年)

摘要

先前所使用於陶瓷雷射膠化法(Ceramic Laser Gelling, CLG)的漿料為氧化矽粉末加入氧化矽膠做備製而成。但由於氧化矽粉末平均粒徑太大在鋪層時會因為剪切力過大而破壞前一次鋪層之薄層；發現製作過程每層層厚最低約為100μm才能做出陶瓷工件，導致層厚太大會有階梯效應及緻密性不高等問題。
本研究的目的是改善陶瓷雷射膠化法，減小最低層厚來改善階梯效應及提高工件燒結後之緻密度，使用漿料是以平均粒徑為0.5μm之氧化鋁陶瓷粉末加上無機黏結劑為矽膠液經過球磨均勻分散後進行鋪層實驗。實驗結果是以總含水量34%之漿料最適合鋪設薄層，目前最低層厚可達到40μm，比以往最低層厚100μm更薄，達到改善階梯效應的效果；但在製作過程中發現經過雷射掃描的部份會因陶瓷粉末顆粒有被帶起的現象，導致緻密度不高。
改良後的CLG製程以氧化鋁粉末添加黏結劑氧化矽膠與PVA所製備之漿料。鋪設後漿料先經過均勻加熱乾燥硬化，再以雷射掃描外輪廓方式，將掃描處視為弱化區，清除弱化區外之生坯後，留下弱化區內未經過雷射掃描部分即為我們的最後工件。結果顯示，在雷射功率12W，掃描速度400mm/s，可將PVA完全燒失，氧化矽膠還能有效抓住顆粒粉末，利用NaOH溶液移除前述之生坯後，取下所需之工件，而所取下之工件經過1600℃高溫燒結後緻密度也可達98.5%，因此可知此製程改良確實能提高燒結後緻密度，也驗證了製程改良後的可行性。

關鍵字

快速原型 ； 陶瓷雷射膠化法 ； 階梯效應 ； 製程改良

並列摘要

Previously, ceramic slurry used in Ceramic Laser Gelling was made up with SiO2 powders and silica gel. Because the average particle size of silica powder was too large, the top layer would be damaged was due to the excess shear stress. In order to make ceramic parts, the thickness of layer should be controlled no less than 100μm which led to the problems of stair-effect and low density of the part.
The purpose of this study is to improve the stair-effect with the thinnest layer and to increase the density of sintered parts. The slurry was made up with 0.5μm alumina powder and silica gel as inorganic binder. After dispersing with a ball mill, the slurry was employed to carry out layer casting experiment. The result showed the optimal water content of slurry was 34% for layer casting. The minimum thickness could be 40μm which was thinner than 100μm obtained previously. Therefore, the stair-effect was improved. However, the density of the workpiece was low due to the ceramic particles were ablated during laser scanning.
The improved process of Ceramic Laser Gelling (CLG) employed slurry which was composed of alumina powder with silica gel and PVA as binders. The fresh layer was solidified by heat and a contour scanning was executed by a laser with scanner. The scanned zone could be treated as a weakened zone. After removing the green portion outside the weakened zone, the remaining green portion inside the weakened zone was the final part. The results revealed that the ceramic particles could be seized when the slurry was scanned at speed of 400mm/s with laser power of 12W. PVA could be burn out completely. After removing the green portion mentioned-above by NaOH solvent, the green workpiece could be obtained. The ceramic workpiece was sintered at 1600 ℃, and then the density of 98.5% was achieved, Consequently, the study demonstrated the feasibility of the improved process which could increase the density of the ceramic part fabricated with CLG.

並列關鍵字

Rapid Prototyping ； Ceramic Laser Gelling ； Stair effect ； Process improvement

參考文獻

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