| Summary: | 碩士 === 國立臺北科技大學 === 資源工程研究所 === 105 === Investment casting has extensive application in different markets, such as mechanical industry, auto parts industry, and aviation industry etc.. Ceramic shell mold for investment casting is mainly formed by Mullite, Zircon and other refractory materials. Most of them are imported with high prices, their remaining waste even need special waste disposal treatment. All these have caused the production costs of investment casting remains high. Taiwan is committed to developing green energy resources, solar power play as an important role of the alternative energy. Silicon wafer is the major material for solar power industry, however, it was reported that approximately 30% of the silicon material would be wasted during the cutting and grinding operation. For now, the Wafer fabrication industry use vacuum distillation or high-speed centrifuge to separate the solid and liquid from the sawing waste slurry. The separated liquid can then be reused as coolant, while the separated solid powder can be further treated to obtain SiC by using hydrocyclone. The recycled SiC can be used as building materials like refractory tiles, bricks.
The study is focusing on the application of recycled silicon carbide (from kerf loss) in ceramic shell mold building of investment casting. The effect of addition amount of SiC powder on mechanical property and casting surface quality have been researched.
This report is in an effort to enhance the economic value of recycling resources in wafer fabrication industry. With the reused SiC powder in building the shell mold approved can effectively reduce production cost for investment casting, meanwhile contributing to the domestically environmental protection.
The study result showed slurry with addition of recycled SiC, modified slurry, can be used as primary and 2nd coating slurry in mold building operation. The PH value of modified slurry showed little variation in comparison with the non-modified slurry. Green strength of shell mold made by modified slurry, modified mold, is about 83%~85% of mold consists of non-modified slurry. Sintering strength of modified shell mold is about 77%~78% of non-modified mold. It’s also been verified that the shell mold’s permeability is proportional to the addition amount of SiC. Casting produced from modified mold surface with some visible minor pin hole,. It is suggested that, for reducing production costs, recycled SiC powder can be added into the slurry to form a modified shell mold when producing castings needed secondary machining operation.
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