| 사출성형에 의한 Al2O3/Paraffin Wax/High Density Polyethylen계 혼합물의 유동성 및 탈지 특성 |
| 김승겸, 신대용1, 한상목1, 강위수2 |
강원대학교 신소재공학과
1강원대학교 신소재공학
2강원대학교 생물산업공학전공 |
| Rheological and Debinding Properties of Al2O3/Paraffin Wax/High Density Polyethylen System Mixture by Injection Molding |
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| ABSTRACT |
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The effects of compositions of binders on the rheological properties of mixtures and the preparation conditions on the formation of defects and the debinding characteristics of compacts for the injection molding of ceramic powders (65 wt% aluminaㆍ35 wt% feldspar) were studied. Ceramic powders were coated with 2 wt% of stearic acid and then mixed with 15, 20, and 25 wt% of Paraffin Wax (PW) and High Density Polyethylene (HDPE) as binders at $160^{circ}C$ for 2 h. Rheological properties were investigated by using capillary rheometer. Apparent viscosities of mixtures were 80∼300 Paㆍs at 1,000$s^{-1}$ of a shear rate, it was good for the injection molding and depending on the compositions of binders. Short shot was formed at 15H5P5 (the ratio of HDPE : PW=5 : 5 in 15 wt% of binders) compacts without injection pressures and any noticeable defects were not formed at 45 kgf/$cm^{2}$ in 20H5P5 compacts. PW and HDPE were removed by the solvent extraction and thermal debinding method. Thermal debinding of HDPE at $450^{circ}C$ for 5 h, which followed the extraction of PW was using n-heptane solvent at $70^{circ}C$ for 5 h. Continuous pores in compacts, which facilitate the removal of HDPE by the thermal debinding, were found to form in the compacts when PW was removed by the solvent extraction. The optimum composition of binder at which binder was removed by thermal debinding without defects while maintaining the compact strength was 20H5P5. Bulk density, porosity and 3-point bending strength of 20H5P5 compact sintered at 1,30$0^{circ}C$ for 5 h were 2.8, < 3%, and 2,400 kgf/$cm^{2}$, respectively, and can be used as a structural materials. |
| Key words:
Ceramic injection Molding, HDPE, PW, Rheological properties, Debinding formation of defects |
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