陶瓷雷射燒結法(CLS)是以陶瓷漿料為素材的陶瓷工件快速原型製程,漿料的固含量會影響到最後工件的緻密度,而在調配高固含量的漿料時,顆粒的分散不佳,容易導致顆粒團聚,增加漿料調配的困難,調配完成的漿料也可能因為分散不佳,使得製作的生坯內顆粒分佈不均勻,導致生坯緻密度不均勻。 本文的目的是研究披覆聚乙烯醇之陶瓷粉末並以聚乙烯醇為黏結劑所備製的漿料流變性,在能夠順利鋪層的條件下,提高漿料的固含量,有助於改善生坯的緻密度。實驗中所使用的粉末為披覆聚乙烯醇的0.2μm球型及0.3μm非球型氧化鋁,藉由不同的pH值及不同含量的Darvan C(分散劑)探討漿料的配方,並以此為基礎備製分散性良好的高固含量漿料。結果顯示,0.2μm球型氧化鋁漿料在pH7、Darvan C 6wt%及0.3μm非球型氧化鋁漿料在pH7、Darvan C 3wt%有良好的分散性,以0.2μm球型氧化鋁所調配之60wt%固含量漿料可製作生坯緻密度56.16%及生工件緻密度53.96%。 以聚乙烯醇為黏結劑的漿料,聚乙烯醇有玻璃轉化溫度(Tg);鋪層時,高於Tg的溫度雖能快速乾燥,但會使薄層表面成膜,當水氣由鋪層內部竄出,造成表面起泡,且生工件易與周遭生坯黏結,生工件無法順利藉由移除生坯而取出。 為了使所鋪薄層能在低於Tg的溫度快速乾燥,本研究以熱風加熱系統搭配現有的底部加熱系統。實驗結果顯示,使用聚乙烯醇為黏結劑的漿料,在鋪層厚度為30μm時,乾燥時間可由60秒改善至15秒。
Ceramic Laser Sintering (CLS) is one of rapid prototyping techniques; it utilizes ceramic slurry as a basic material. The solid content in the slurry will affect the density of green part. Increasing solid content will cause poor dispersion which easily leads to agglomeration, and cause difficulty of stirring the slurry. Due to the poor dispersion, the density of the green block may not be uniform. The aim of this paper is to study on the rheology of the slurry which is the mixture of the binder and alumina powder coated by polyvinyl alcohol. The binder is also polyvinyl alcohol. Under a prerequisite of successful casting, increasing solid content can improve the density of green block. The materials in this paper were 0.2μm spherical and 0.3μm non-spherical alumina coated by polyvinyl alcohol. The optimal composition of the slurry was studied by varying pH and Darvan C content. The result indicated that 0.2μm spherical alumina had a good dispersion in pH7 with Darvan C 6wt%, and 0.3μm non-spherical alumina had a good dispersant in pH7 and Darvan C 3wt%. The densities of green block and green part, which were fabricated with 0.2μm spherical alumina slurry with 60wt% solid content, were 56.16% and 53.96% respectively. The polyvinyl alcohol as a binder contained in the slurry has glass transition temperature (Tg). The thin layer can be dried fast by a temperature higher than Tg, but a thin film will be formed on the surface of the layer. Such phenomenon will induce bubbles when the water is vaporized from the inner layer, and will cause the green part binds the green portion. Eventually, the green part will not be separated from the green block by green portion removal. For speeding drying at a temperature below Tg, this study utilized a hot-air system accompanied to the existing heating system. The result indicates the drying time of the 30μm thin layer casted with the slurry contained the binder polyvinyl alcohol was shortened from 60 seconds to 15 seconds.
為了持續優化網站功能與使用者體驗,本網站將Cookies分析技術用於網站營運、分析和個人化服務之目的。
若您繼續瀏覽本網站,即表示您同意本網站使用Cookies。