• Title/Summary/Keyword: heavy alloy

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The Effects of the Distribution Aspect of Precipitate on the Corrosion Behavior of As-Cast Magnesium Alloys

  • 이충도
    • Transactions of Materials Processing
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    • v.8 no.3
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    • pp.295-295
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    • 1999

  • In the present study, the corrosion behavior of AZ91D as-cast alloy was investigated form the viewpoint of the distribution aspect of precipitate ($Mg_{17}Al_{12}$) and the variation of Al concentration in the Mg-rich matrix. The dendrite arm spacing (DAS) of an as-cast specimen was measured as a function of degree which describes the distribution aspect of the precipitate, and the salt spray test was conducted for various grain-sired specimens fur 20 days. The dendrite arm spacing increased as the grain size increased to about 150㎛, but a constant value is indicated when the grain size exceeds that range. Although the relationship between the corrosion rate and grain size is of a nonlinear type, the linear trend between the corrosion rate and the dendrite arm spacing is maintained for the overall range of dendrite arm spacing. Since the precipitate in the as-cast alloy is discontinuously distributed, this linear relationship means that the variation of Al-solute concentration in the Mg-rich matrix has a more potent effect than the protective action of the precipitate on the corrosion behavior of an as-cast alloy.

Sintering Behavior of the Injection Molded W-Ni-Fe Heavy Alloy by Addition of Metallic Stat (금속 염 첨가 방법을 이용하여 사출성형된 텅스텐 중합금의 소결거동)

  • 김대건;류성수;김은표;이정근;김영도;문인형
    • Journal of Powder Materials
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    • v.6 no.4
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    • pp.294-300
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    • 1999

  • This study was carried out to investigate the possibility whether Metal Injection Molding (MIM) process could be applied to 95wt.%W-3.5wt.%Ni-1.5wt.%Fe heavy alloy in order to obtain an intricate shape. Methylcellulose was used in the injection molding for binder. $FeCl_2-4H_2O$ was added in solvent substituting Fe powder and $FeCl_2$ was doped on W-Ni premixed powder. When $FeCl_2-4H_2O$ was added in solvent, the binder separation occurred for injection molding so that the matrix content was changed. Such problem was solved when $FeCl_2$ was doped. In this study. the debinding process did not affect residual carbon content. The sintered microsouctures as addition methods of Fe element and the sintering temperature from $1420^{\circ}C$ to $1470^{\circ}C$, which are around the temperature of liquid phase formation, were observed.

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The survival rate, respiration and heavy metal accumulation of abalone (Haliotis discus hannai) rearing in the different copper alloy composition (동합금 조성에 따른 북방전복 (Haliotis discus hannai)의 생존, 호흡 및 중금속 축적률)

  • Shin, Yun-Kyung;Jun, Je-Cheon;Myeong, Jeong-In;Yang, Sung-Jin
    • The Korean Journal of Malacology
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    • v.30 no.4
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    • pp.353-361
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    • 2014

  • In order to investigate the effects of copper alloy on abalone physiology, we studied survival rate, respiration, excretion rate, and heavy metal accumulation in each organ of adults and spats. The survival rate of spats and adults showed 27-60% and 63-83% respectively, higher survival rate in adults. In particular, 100% of copper panel led to lowest survival rate and there was no sharp distinction according to copper alloy composition. The respiration rate and excretion rate of ammonia nitrogen was $1.81mgO_2/g$ D.W./h and 0.43 mg $NH_4-N/g$ D.W./h respectively at 100% of copper panel. In other words, there was a high significant difference at the level, but no significant difference at other test levels (P < 0.05). The atomic ratio (0: N) hit the lowest at the 100% of copper panel showing 3.79 and no significant differences were seen among other test groups with 6.57-7.18 of a very low range. This means that the species might have undergone nutritional stress. In case of copper accumulation, the 100% copper panel group showed the highest level in hepatopancreas and muscle showing 6.91 mg/kg and 1.60 mg/kg respectively but the rest of groups showed similar levels. Zinc accumulation raised at Cu-Zn alloy panel had high significance showing 18.50 mg/kg and 1.10 mg/kg in hepatopancreas and muscle respectively (P < 0.05). To sum up, a cage net made of 100% pure copper is expected to have a negative effect on abalone in light of survival rate, heavy metal accumulation, and atomic ratio (0: N). Moreover, given that the substratum used for the high adhesive species and nutritious stress that is represented through the atomic ratio need to be considered, the copper alloy net is thought not to be suitable for abalone aquaculture.

  • https://doi.org/10.9710/kjm.2014.30.4.353 인용 PDF KSCI