Study of Refractory Coating in the Lost Foam Casting Process
| Autor: | Ann-Shing Chang, 張安欣 |
|---|---|
| Rok vydání: | 2000 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 88 This study measured the pressures developed during filling experiment using molten gray iron in the lost foam casting (LFC) process. The measured pressures included back pressure, and permeable pressure. The back pressure responded from in-mold of metal-foam interface. The permeable pressure was measured on the mould side of the coating, when gases introduced from the decomposing EPS were permeating through coating. The permeable pressure reflected the permeability of the coating while filling molten iron. This study also performs many pouring trials using a special design pattern with different coatings to evaluate the factors influencing the hot strength of coating. Strengths of coating at room temperature are also measured for comparison. Variables, which included particle sizes, types of binders, weight per cent of binder in coatings, influenced the permeability and strength of coating at room temperature and at casting temperature. Experimental results show that the coating made from flaky alumina developed a greater total length of pore channels than those made from angular silica. Increasing the particle size of the refractory increased the permeability of the coating at room temperature. The highest permeable pressure was measured. When the particle size was 74 m and acrylic resin was used as a binder. The optimum binder content was less than 1% for flaky alumina and acrylic resin binder. The optimum coating thickness was less than 0.5 mm to develop a maximum permeable pressure associated with a minimum back pressure in the mould. For a given particle size or for a given wt% of a binder, the coating added with flaky alumina and acrylic resin (binder B) develops the greatest strength at room temperature and its hot strength. If a polyvinyl acetate resin (binder A) is used, coating generally develops an inferior strength to that of acrylic resin (binder B). For a given resin added in coating, angular silica used as the refractory particle decreases the strength of coating at room temperature and its hot strength. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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