• Corrosion Science and Technology
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• 제7권4호
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• pp.237-242
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• 2008

Physical properties of water, such as dielectric constant and ionic product, significantly vary with the density of water. In the supercritical conditions, since density of water widely varies with pressure, pressure has a strong influence on physical properties of water. Dielectric constant represents a character of water as a solvent, which determines solubility of an inorganic compound including metal oxides. Dissociation equilibrium of an acid is also strongly dependent on water density. Dissociation constant of acid rises with increased density of water, resulting in drop of pH. Density of water and the density-related physical properties of water, therefore, are the major governing factors of corrosion and environmentally assisted cracking of metals in supercritical aqueous solutions. This paper discusses importance of "physical properties of water" in understanding corrosion and cracking behavior of alloys in supercritical water environments, based on experimental data and estimated solubility of metal oxides. It has been pointed out that the water density can have significant effects on stress corrosion cracking (SCC) susceptibility of metals in supercritical water, when dissolution of metal plays the key role in the cracking phenomena.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.11-18
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• 1996

The toxic metal ion release behaviour and the cytotoxicity of a super stainless steel (S.S.S, 22cr-20Ni -6Mo-0.25N) were investigated The measurement of the amount of static and wear- induced trace metal ion released from the steels was conducted in Hank's balanced salt solution using an electrothermal atomic absdrption spectrometry equiped with Uaphite furnace. And the in vitro cytotoxicity of the materials was assesed in cell culture. The static dissolution rates of Fe and Cr ions from the S.S.S were significantly lower than those of 316L SS. However, the Ni ion release from the S.S.S during the first 4 weeks was yester than that from 316L 55 by 15-45%. Also, the wear-in- duces dissolution rates from the steels were not correlated either with their elemental composition rates or with the static metal ion release rates. The S.S.S did not deteriorate the osteoblasts viability. And no toxic response was observed from the macrophages cultured for 7 days in RFMI 1640 medium immersed with the S.S.S specimens.

• 자원리싸이클링
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• 제30권3호
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• pp.41-46
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• 2021

메탄술폰산은 우수한 물리화학적 특성을 지니고 있어 금속의 침출에 효과적이다. 분자구조 및 코발트와 니켈 금속의 침출자료를 이용하여 메탄술폰산과 황산의 화학적 반응성을 비교하였다. 유발과 공명효과는 두 산의 반응성에 큰 영향을 미쳤다. 동일한 침출조건에서 코발트와 니켈의 침출률은 메탄술폰산보다 황산에서 높았다. 메탄술폰산의 강한 산도와 금속염의 높은 용해도를 고려하면 메탄술폰산을 금속회수시 침출제로 이용하는 것이 가능하다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.393-396
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• 2003

Soil contains the several kinds of metal oxides. Magnetite in soil may contribute the generation of secondary waste during the decontamination of soil by citric acid. Dissolution of magnetite powders by citric acid was investigated in the pH range between 2.0 and 5.0. The dissolution behaviour of magnetite was well described by the equation, A[1 - $e^{-B(x-c)}$]. The parameters of the equation were optimized by the iteration method, and the physical meaning of each parameter was explained. Concentration of each of the dissociated chemical species of citric acid was calculated using the ionization constants. The dissolution reaction was explained by the concentration of the dissociated chemical species of citric acid.d.

• 대한치과기공학회지
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• 제34권3호
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• pp.237-245
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• 2012

Purpose: This study was conducted to evaluate the corrosion resistance of metal ions of alloys and use the results as the dental health data. These were performed by examining the corrosion levels of Co-Cr alloys for the full and removable partial denture metal frameworks and porcelain-fused-to-metal crown, among the dental casting nonprecious alloys. Methods: The alloy specimens (N = 10) were manufactured in $15mm{\times}10mm{\times}1.2mm$ and stored in two types of corrosive solutions at $37^{\circ}C$ for seven days. The metal ions were quantitatively analyzed using the Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: Of the three Co-Cr alloys, the Co ion concentration of the porcelain-fused-to-metal alloy was 1.512 ${\mu}g/cm^2$, which indicated the highest metal ion dissolution. The metal corrosion was higher in the more acidic pH 2.2 solution compared with the pH 4.4 solution. In all three Co-Cr alloys, Co ion dissolution was predominant in the two corrosive solutions. Conclusion: The corrosion resistance of the three Co-Cr alloys was high, indicating a good biocompatibility.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.231-233
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• 2006

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.263-265
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• 2006

• 마이크로전자및패키징학회지
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• 제24권4호
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• pp.1-7
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• 2017

Aluminum alloys have been widely used in many fields such as electronic, structure, aero-space and vehicle industries due to their outstanding thermal and electrical conductivity as well as low cost. However, they have some difficulties for using in brazing process because of the strong oxide layer of $Al_2O_3$ on the surface of Al alloy. In addition, their melting point is similar to that of brazing filler metal resulting in thermal damage of Al alloys. Therefore, it is very important to understand the brazing principles, filler metal and its properties such as wetting, capillary flow and dissolution of base metal in the Al brazing process. This paper reviews the brazing principles, aluminum alloys, and brazing fillers. In the case of brazing principle, some formula was used for calculation of capillary force and the dissolution to obtain the best condition of Al brazing. In addition, the advanced research trends in Al brazing were introduced including thermal treatment, additive for improving property and decreasing melting point in Al brazing process.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.12-13
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• 2012

An environmentally friendly method for in situ growth of Mg-Al hydrotalcite (HT) film on AZ31 magnesium alloy has been developed. The growth processes and corrosion resistance of the HT film were investigated. Then the HT film was surface modified by phytic acid solution to further improve the corrosion resistance. The film formation involves the dissolution of AZ31 substrate, adsorption of the ions from solution, nucleation of the precursor, followed by the dissolution of $Al^{3+}$, exchanging of $OH^-$ by $CO{_3}^{2-}$ and growth of the HT film. The HT film is very compact and acts as a barrier against $Cl^-$ attack in the early stage of corrosion, and then the surface of the film is dissolved gradually. This dense HT film can provide effective protection to the AZ31 alloy. The HT film with surface modification by phytic acid presents a self-healing feature and exhibits better corrosion resistance.

• 한국세라믹학회지
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• 제43권1호
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• pp.33-37
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• 2006

For producing the fine ribs structure of plasma display panel, the metal ions of barrier materials during the etching process should be understood on the etching mechanism with etching conditions. Etching was done on bulk glasses of the $BaO_B_2O_3-ZnO$ system with $HNO_3$ solution at $40^{\circ}C$. The surface structure of glasses and ion dissolution were analyzed by ICP (Inductive Coupled Plasma measurement). The structure and surface of the etched bulk glass were investigated by using scanning electron microscopy and nanoindenter. As a result, Ba (3-35 ppm/min) and Zn (2-27 ppm/min) ions as major components were leached in the solution and the leached layers were found to be phosphor-rich surface layers. A decrease of the bridge oxygen and relative increase of non bridge oxygen in the etched glass were found by X-ray photoelectron spectroscopy.