• 한국세라믹학회지
• /
• 제40권8호
• /
• pp.720-724
• /
• 2003

Aluminum nitride (AlN) powders were synthesized by using a mixture of an aluminum nitrate or sulfate salt and carbon (mole ratio of $Al^{3+}$ to carbon=L : 30). The AlN was obtained by calcining the mixture under a flow of nitrogen in the temperature range 1100-1$600^{\circ}C$ and then burning out the residual carbon. The process of conversion of the salt to AlN was monitored by XRD and $^{27}$ Al magic-angle spinning (MAS) NMR spectroscopy. The salt decomposed to ${\gamma}$-alumina and then converted to AlN without phase transition from ${\gamma}$-to-$\alpha$-alumina. $^{27}$ Al MAS NMR spectroscopy shows that the formation of AlN commenced at 110$0^{\circ}C$. AlN powders obtained from the sulfate salt were superior to those from the nitrate salt in terms of homogeneity and crystallinity. A very small amount of AlN whiskers was obtained by calcining a mixture of an aluminum sulfate salt and carbon at 115$0^{\circ}C$ for 40 h, and the growth of the whiskers is well explained by the particle-to-particle self-assembly mechanism.

• 상하수도학회지
• /
• 제33권6호
• /
• pp.413-420
• /
• 2019

Pretreatment system of desalination process using seawater reverse osmosis(SWRO) membrane is the most critical step in order to prevent membrane fouling. One of the methods is coagulation-UF membrane process. Coagulation-UF membrane systems have been shown to be very efficient in removing turbidity and non-soluble and colloidal organics contained in the source water for SWRO pretreatment. Ferric salt coagulants are commonly applied in coagulation-UF process for pretreatment of SWRO process. But aluminum salts have not been applied in coagulation-UF pretreatment of SWRO process due to the SWRO membrane fouling by residual aluminum. This study was carried out to see the effect of residual matal salt on SWRO membrane followed by coagulation-UF pretreatment process. Experimental results showed that increased residual aluminum salts by coagulation-UF pretreatment process by using alum lead to the decreased SWRO membrane salt rejection and flux. As the salt rejection and flux of SWRO membrane decreased, the concentration of silica and residual aluminum decreased. However, when adjusting coagulation pH for coagulation-UF pretreatment process, the residual aluminum salt concentration was decreased and SWRO membrane flux was increased.

• 한국주조공학회지
• /
• 제20권1호
• /
• pp.38-45
• /
• 2000

The remelting for recycling or thin aluminum scrap, such as aluminum chip generally involves melting of these pieces submerged in molten salt flux. In this study, the effects of salt flux compositions and alloying elements on the aluminum dropletscoalescence and oxide film removal were studied in 99.8%Al, Al-1.01%Cu, Al-1.03%Si, and Al-1.38%Mg alloys as a function of holding time at $740^{\circ}C$ Salt fluxes based on NaCl-KCl(1:1) with addition of 5wt.% fluorides(NaF, $Na_3AlF_6$, $CaF_2$) or 5 wt.% chloride($MgCl_2$, $AlCl_3$) were used. The experimental results show that NaCl-KCl(1:1) with addition of 5 wt.% fluorides exhibits better coalescence ability than that with chlorides. The oxide film is not removed by NaCl-KCl(1:1) with addition of 5 wt.%chlorides, while it is removed by NaCl-KCl(1:1) with addition of 5 wt.% fluorides. The aluminum droplets coalescence and oxide film removal by salt fluxes are related to interfacial tension tension between metal and salt flux.

• 한국세라믹학회지
• /
• 제27권7호
• /
• pp.851-860
• /
• 1990

The hydrolysis-precipitation reaction of mixed aluminum salt solutions of aluminum sulfate, aluminum nitrate, and urea has been investigated to obtain narrow-sized and unagglomerated fine spherical precipitates of aluminum hydroxide required for coating core particles. The hydrolysis-precipitatin reaction could be controlled to be appropriate to coating processes by usign urea as a pH control-agent. As the concetration of total Al3+ ion and the molar ratio of SO42-/Al3+ in starting solutions became smaller and also as the vol. ratio of water/solution for hydrolyzing mixed aluminum salt solution became larger, the morphology of precipitates tended to be more unagglomerated and spherical, while their size(0.5longrightarrow0.05${\mu}{\textrm}{m}$) to be smaller. The optimum hydrolysis condition for coating processes was to hydrolyze the mixed aluminum salt solution, in which the molar ratio of SO42-/Al3+ was 0.75, while the amount of water corresponding to the vol. ratio of water/solution of 15. The precipitate was the aluminum hydroxide which sulfate ions were strongly adsorbed on and the maximum yield in the hydrolysis-precipitation reaction was about 20%.

• 자원리싸이클링
• /
• 제6권1호
• /
• pp.5-10
• /
• 1997

알루미늄 드로스로부터 알루미늄 회수에 관한 연구를 행하였다. 알루미늄 드로스의 발생량이 가장 많은 중립(1.0~12.0mm)의 드로스를 시료로 하여 $850^{\circ}C$의 용해온도와 용해 2시간에서 염화나트륨과 염화칼륨의 첨가 영향은 40% 첨가시 약 76.9%로 최대 회수율을 얻었으며, 그 이상 첨가는 점성의 증가로 회수율에 별 영향을 미치지 않았다. 한편, 40%의 기본염용제에 NaF, $CaF_2$, $AlF_3$ 및 ${Na}_{3}{AlF}_{6}$ 첨가시 5%에서 최대 회수율을 나타내었으며, 특히 5%의 빙정석 첨가시 약 83.5%의 최대 회수율을 얻을 수 있었다. 그러나 불화물을 5% 이상 첨가시에는 점성이 증가하여 알루미늄 회수율에 큰 영향을 미치지 않았다.

• 전기학회논문지
• /
• 제58권9호
• /
• pp.1764-1768
• /
• 2009

As the demand of electric power is increasing rapidly, the need of the compact and light electric power device is also increased. Copper clad aluminum (CCA) is newly proposed electrical conductor, because of its light-weight and low-cost characteristics, to replace the existing conductor made of copper. This paper presents the salt-proof characteristics of the copper clad aluminum (CCA) to certificate long time safe operation of the newly proposed electrical conductor. The two types of the CCA conductor were tested in the neutral salt spray tester. The experimental results of two types of the CCA with salt spray were presented in this paper. The results comprise resistance measured data, micro picture of the selected surface, and component measured data according to the elapsed time. The period of the experiment was 1,000 hours. There was no evidence to show the corrosion of CCA during the whole period of the experiments.

• Journal of Advanced Marine Engineering and Technology
• /
• 제33권6호
• /
• pp.860-866
• /
• 2009

It is very important to choose optimal material having good corrosion resistance and capabilities for the part materials such as the automotive exhaust system under a hot salt corrosion atmosphere. Generally, two types of corrosion come into the automotive exhaust system. One is 'Condensate Corrosion', which is occurred by exhaust gas condensate formed at the inner surface of exhaust system heated up during driving, which results in the acid condensate pitting. The other is 'High Temperature Salt Corrosion' occurring from the interaction between the chloride ion coming from salt at the seaside district or snow salt and the outer surface of exhaust system. By the corrosion attack, the main muffler is firstly damaged and the life cycle of an automobile is significantly decreased. It has been investigated that the hot salt corrosion properties of a STS 409L and 436L ferritic stainless steels which are well-known for the materials of the automotive exhaust system. In addition, the corrosion properties of hot dip aluminum coated STS 409L have been compared with uncoated steels. Aluminum coated STS 409L showed a superior corrosion resistance than uncoated STS 409L, and futhermore showed a better corrosion resistance than a STS 436L, which is an expensive ferritic stainless steel having a excellent corrosion resistance caused from more chromium content of an alloying element.

• 자원리싸이클링
• /
• 제27권5호
• /
• pp.61-68
• /
• 2018

알루미늄 드로스는 알루미늄 용해 공정에서 용탕 표면에 발생하는 산화물 덩어리로서, Salt 유무에 따라 화이트드로스와 블랙드로스로 구분된다. 화이트드로스의 경우 금속 함량이 높아 용해 공정으로 재활용 되지만, 블랙드로스는 금속 함량이 낮고 성분 분리가 어려워 대부분 매립 처리되며, 물과 반응하면 가스와 발열 반응이 일어나 토양오염의 원인으로 작용한다. 하지만 블랙드로스에는 NaCl과 KCl과 같은 Salt 성분과, $Al_2O_3$, MgO와 같은 무기소재가 포함되어 있어 이러한 유가자원을 회수하고 소재화하는 기술 연구가 필요하다. 본 연구에서는 알루미늄 블랙드로스를 재활용하기 위한 공정을 제시하였다. 파쇄-용해(Dissolution)-고액분리-감압증발을 거치는 공정을 통하여 블랙드로스에 존재하는 무기물과 용해성 물질을 분리하였다. 물과 블랙드로스 함량을 제어하여 조건에 따라 분리물의 회수율을 최적화하였으며, 블랙드로스:물 비율이 1:9 일 때 91 wt.%의 Salt flux 회수율을 보임을 확인하였다. 추가적으로, 회수된 무기물을 이용한 제올라이트의 합성을 통하여 블랙드로스의 소재화 가능성을 확인하였다.

• 동아시아식생활학회지
• /
• 제7권4호
• /
• pp.512-518
• /
• 1997

알루미늄 등 중금속 오염이 점점 심화되고 있는 서해안 일부지역에서 포획되고 있는 46종의 어패류 중 알루미늄 함량의 평균은 88.38$\pm$189.03ppm으로 그 범위는 0.97-827.70ppm이었는데 24종의 생선 중 알루미늄 함량은 그 범위가 0.97ppm에서 45.12ppm으로 건실치에 가장 많았고 도미에 가장 적게 함유되어 있었다. 15종의 연체류가 함유하고 있는 알루미늄 함량은 3.40ppm에서 827.70ppm으로 그 차이가 매우 컸는데 복족류인 소라에 3.40ppm으로 가장 적게 함유되어 있었고 이매패류인 대합에 826ppm, 해락에 812.55ppm으로 가장 많이 함유되어 있었다. 7종의 젓갈의 알루미늄 함량은 2.50-295.15ppm으로 그 차이가 컸는데 황새기젓과 한치젓에는 그 함유량이 낮았지만 조개젓과 곤쟁이젓에는 많은 양의 알루미늄이 함유되어 있었다 생선과 연체류 및 젓갈중에 함유되어 있는 알루미늄 함량간의 유의차를 검증한 결과 연체류의 알루미늄 함량이 생선과 젓갈에 비해 유의적으로 높았다(p＜0.01), 이는 일생동안 주거지를 크게 움직이지 않는 생육조건을 갖는 이매패류의 특성때문으로 사료된다.

• 한국표면공학회지
• /
• 제32권3호
• /
• pp.452-455
• /
• 1999

ORV which vaporizes LNG to NG is consisted of tube and header whose substrate is aluminum alloy. The corrosion of the tube is very severe because of sea water being used as the heating source. In this research to protect ORV substrate material, the corrosion behavior of aluminum alloys was investigated for the sacrificial role of Al-Zn alloy for ORV tubes. The electrochemical behavior of aluminum alloys in sea water was investigated. The corrosion behavior of thermally-sprayed and cladded samples were compared through salt spray tests. Al-Zn alloy can act as a sacrificial anode and cladded Al-Zn alloy has a better corrosion resistance than that of thermally sprayed one. The galvanic effect of Al-Zn to substrate material was conformed from scratched sample tests.