• Title/Summary/Keyword: hot-pressing

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Research on Two Sintered Techniques of Nanometer WC-Co Powder

  • Sun, Lan;Jia, Chengchang;Tang, Hua
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.529-530
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    • 2006

  • This paper concerned with SPS (spark plasma sintering), hot pressing of sinter nanometer WC-Co powder and discussed the density, hardness, microstructures and grain sizes of the alloys sintered. The results showed that the two sintered techniques could produce high density alloys and play well on the grain growth, but SPS could lower the sintering temperature and shorten sintering time. Besides, the hardness of the sintered cemented alloys that was dependent on the grain size and densification could also be improved.

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Modelling the Densification Behaviour of Powders Considering Diffusion and Power-Law Creep Mechanisms during Hot Isostatic Pressing (열간정수압압축 시 확산기구 및 Power-law크립기구를 고려한 분말 치밀화거동의 모델링)

  • 김형섭
    • Journal of Powder Materials
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    • v.7 no.3
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    • pp.137-142
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    • 2000

  • In order to analyze the densification behaviour of stainless steel powder compacts during hot isostatic pressing (HIP) at elevated temperatures, a power-law creep constitutive model based on the plastic deformation theory for porous materials was applied to the densification. Various densification mechanisms including interparticle boundary diffusion, grain boundary diffusion and lattice diffusion mechanisms were incorporated in the constitutive model, as well. The power-law creep model in conjunction with various diffusion models was applied to the HIP process of 316L stainless steel powder compacts under 50 and 100 MPa at $1125^{\circ}C$. The results of the calculations were verified using literature data. It could be found that the contribution of the diffusional mechanisms is not significant under the current process conditions.

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Development of Rice Hull Insulation Board using Urea Formaldehyde Resin (요소수지(尿素樹脂) 연질(軟質) 왕겨보드의 개발(開發))

  • Lee, Hwa-Hyoung;Kang, Chun-Won
    • Journal of the Korean Wood Science and Technology
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    • v.26 no.4
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    • pp.50-55
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    • 1998

  • This study was carried out to develop low density board made of rice hull which needs proper use. Urea formaldehyde adhesive(UF) was used. The raw materials were the mixtures of the rice hulls from IllFum, DongGin, ChuChong, etc. The physical and mechanical properties of rice hull insulation board were examined. The results are as follows : For the thickness of 15mm of the low density rice hull board bonded with UF resin, proper manufacturing conditions were $171^{\circ}C$ of hot pressing temperature with thickness bar for optimum density, 12 percent of resin solid contents of rice hull ovendry weight, and 20 minutes of hot pressing time. These conditions meet Korean standards(KS 3201-1982) in relation to free formaldehyde emission, bending strength, water absorption and heat resistance.

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