• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.69-78
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• 1998

Thermal sprayed Cu-Ni alloy coating on the carbon steel was carried out impingement erosion-corrosion test and electrochemical corrosion test in the marine environment. The impingement erosion-corrosion behavior and electrochemical corrosion characteristics of substrate(SS400) and thermal sprayed Cu-Ni coating was investigated, and the corrosion control efficiency of Cu-Ni coating to substrate was estimated quantitatively. Main results obtained are as follows : 1) The weight loss rate of Cu-Ni coating layer by the impingement erosion-corrosion compared with substrate was smaller in high specific resistance solution than in low specific resistance solution. 2) The corrosion potential of Cu-Ni coating layer spray coating in the marine environment became more noble than that of substrate. 3) With the lapse of time, corrosion current density of Cu-Ni coating layer became stable, but that of substrate was increased. 4) As the corrosion control efficiency of Cu-Ni coating layer in the marine environment was over 90%, its anti-corrosion characteristics was excellent.

• Corrosion Science and Technology
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• v.23 no.1
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• pp.64-71
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• 2024

The objective of this study was to investigate corrosion and cavitation-erosion characteristics of the electroless nickel plating layer with heat treatment. The crystallization temperature of the electroless nickel plating layer was about 410 ℃. The phase transformation energy was confirmed to be 12.66 J/g. With increasing heat treatment temperature, the amorphous electroless nickel plating layer gradually changed to crystalline Ni and Ni₃P. At the same time, the crystal grain size was also increased. Additionally, when heat treatment was performed at a temperature above 400 ℃, NiO phase was observed due to oxidation phenomenon. As a result of the electrochemical polarization experiment, the corrosion resistance of the heat-treated electroless nickel plating layers was superior to that of the as-deposited plating layer. This was because crystal grains became larger and grain boundaries decreased during heat treatment. The cavitation-erosion resistance of heat-treated plating layers tended to be superior to that of as-deposited plating layers due to increased microhardness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.117-120
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• 1998

It is analyzed the erosing process of the polymeric insulator for outdoor use with the inclined plane method. Materials used are the different type of silicone rubber, they have the content of filler and component each other. As the content of filler added to improve the tracking and erosion resistance. It has the difference of electrical performance and erosion rate. The dry-band arc is also the parameter of accelerating erosion, and appear in the form of leakage current, and the activities of leakage current has a close relationship with the surface hydrophobicity. In this paper, the erosion growth is observed by measuring the time from the voltage application to the whole breakdown, and the erosion depth. In addition, it is measured the hydrophobicity and leakage current to be a cause of erosion by the erosion steps, studied SEM, EDX for observing the transformation of surface structure by erosing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.140-143
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• 2004

Chemical mechanical polishing(CMP) is essential technology to secure the depth of focus through the global planarization of wafer. But a variety of defects such as contamination, scratch, dishing, erosion and corrosion are occurred during CMP. Especially, dishing and erosion defects increase the resistance because they decrease the interconnect section area, and ultimately reduce the life time of the semiconductor. Due to this dishing and erosion must be prohibited. The pattern density and size in chip have a significant influence on dishing and erosion occurred over-polishing. Decreasing of abrasive concentration results in advanced pattern selectivity which can lead the uniform removal in chip and decrease of over-polishing. The fixed abrasive pad was applied and tested to reduce dishing and erosion in this paper. Consequently, reduced dishing and erosion was observed in CMP of tungsten pattern wafer with proposed fixed abrasive pad and chemicals.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.38-45
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• 2005

Chemical mechanical polishing(CMP) has been widely accepted for the planarization of multi-layer structures in semiconductor fabrication. But a variety of defects such as abrasive contamination, scratch, dishing, erosion and corrosion are occurred during CMP. Especially, dishing and erosion defects increase the metal resistance because they decrease the interconnect section area, and ultimately reduce the lift time of the semiconductor. Due to this reason dishing and erosion must be prohibited. The pattern density and size in chip have a significant influence on dishing and erosion occurred by over-polishing. The fixed abrasive pad(FAP) was applied and tested to reduce dishing and erosion in this paper. The abrasive concentration decrease of FAP results in advanced pattern selectivity which can lead the uniform removal in chip and declining over-polishing. Consequently, reduced dishing and erosion was observed in CMP of tungsten pattern wafer with proposed FAP and chemicals.

• Journal of Korea Foundry Society
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• v.30 no.4
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• pp.142-146
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• 2010

To elucidate the characteristics of cavitation erosion of super duplex stainless steel, a cavitation erosion test, an optical microstructure, a hardness test, and a transmission electron microscope (TEM) analysis were conducted. As aging time at $475^{\circ}C$ increased, the hardness of ferrite phase increased whereas that of austenite phase was nearly constant. The reason why the cavitation erosion resistance increased with an increase of aging time was due to the formation of W-rich phases (${\alpha}$') of a nanometer scale with the high hardness that were precipitated within ${\alpha}$-grains and at ${\alpha}$-grain boundaries during aging, compared with that of the solution annealed alloy.

• Journal of the Korean Geographical Society
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• v.42 no.1 s.118
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• pp.27-40
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• 2007

The streams evolve to diverse forms influenced by various factors such as rock resistance tectonic process, sediments and discharge. This study focuses on erosion resistance of rocks among these factors. The morphology of plane and longitudinal profile has been analysed in upper and lower reach of 6 streams using GIS; Yeoryong-cheon, Heungjeong-cheon, Duhak-cheon, Daehwa-cheon, Namcheon-cheon, Guryong-cheon, having distinct bedrock types between upper and lower reach. While the basins of granite have gentle slope, low concavity and wide valley area, those of gneiss form steep slope, high concavity and narrow valley area. However, the basins of sedimentary rock make steep slope and high relief in main channel, the other features show some differences in each stream. Among the various morphological features, the indices on slope and concavity of main channel, drainage density, ratio of valley area, average slope and average relief of the basin which have clear differences between rocks in upper and lower reach are calculated to interpret the erosion resistance of rocks in upper and lower reach. As a result, the upper reaches composed of gneiss have the highest erosion resistance, sedimentary rocks in upper and lower reaches show moderate resistance, and granite reaches generally have the lowest resistance except the upper reaches bordered by sedimentary rock.

• Corrosion Science and Technology
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• v.13 no.2
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• pp.70-80
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• 2014

Duplex stainless steels with nearly equal fraction of the ferrite(${\alpha}$) phase and austenite(${\gamma}$) phase have been increasingly used for various applications such as power plants, desalination facilities due to their high resistance to corrosion, good weldability, and excellent mechanical properties. Hyper duplex stainless steel (HDSS) is defined as the future duplex stainless steel with a pitting resistance equivalent (PRE=wt.%Cr+3.3(wt.%Mo+0.5wt.%W)+30wt.%N) of above 50. However, when HDSS is welded with gas tungsten arc (GTA), incorporation of nitrogen in the Ar shielding gas are very important because the volume fraction of ${\alpha}$-phase and ${\gamma}$-phase is changed and harmful secondary phases can be formed in the welded zone. In other words, the balance of corrosion resistance between two phases and reduction of $Cr_2N$ are the key points of this study. The primary results of this study are as follows. The addition of $N_2$ to the Ar shielding gas provides phase balance under weld-cooling conditions and increases the transformation temperature of the ${\alpha}$-phase to ${\gamma}$-phase, increasing the fraction of ${\gamma}$-phase as well as decreasing the precipitation of $Cr_2N$. In the anodic polarization test, the addition of nitrogen gas in the Ar shielding gas improved values of the electrochemical parameters, compared to the Pure Ar. Also, in the erosion-corrosion test, the HDSS welded with shielding gas containing $N_2$ decreased the weight loss, compared to HDSS welded with the Ar pure gas. This result showed the resistance of erosion-corrosion was increased due to increasing the fraction of ${\gamma}$-phase and the stability of passive film according to the addition $N_2$ gas to the Ar shielding gas. As a result, the addition of nitrogen gas to the shielding gas improved the resistance of erosion-corrosion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.99-104
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• 2017

Refractories used in low-rank coal gasification reactors are usually exposed in a highly corrosive $H_2S$ gas at less than $1000^{\circ}C$, and their mechanical properties such as erosion resistance and fracture strength decline with the exposure time. However, the cause of the degradation of the mechanical properties has little reported yet. In this paper, two kinds of castable refractories with different refractoriness had been exposed in a $H_2O/N_2/H_2S$ mixed gas with high $H_2S$ content for 100 hours at $900^{\circ}C$, and the changes of microstructure, crystalline phases and erosion resistance were compared before and after the corrosion test. The weight of the refractories decreases due to the elution of silica in the specimens after the corrosion test. The capillary porosities of the samples are reduced, but the erosion resistance of the samples is fatally weakened after the corrosion test. There also are changes in constituent phases; dmitryivanovite ($CaAl_2O_4$) and amorphous silica ($SiO_2$) disappear, and gypsum ($CaSO_4{\cdot}2H_2OS$) and kaolinite ($Al_2Si_2O_5(OH)_4$) newly appear after the corrosion test. It is obvious that the phase change from dmitryivanovite that works as a binding agent in the castable refractory to gypsum is the main reason of the degradation of the erosion resistance, because the mechanical properties of gypsum are much poorer than those of dmitryivanovite.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1117-1120
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• 2001

Chemical mechanical planarization(CMP) has emerged as the planarization technique of choice in both front-end and back-end integrated circuit manufacturing. Conventional CMP process utilize a polyurethane polishing pad and liquid chemical slurry containing abrasive particles. There have been serious problems in CMP in terms of repeatability and defects in patterned wafers. Since IBM's official announcement on Copper Dual Damascene(Cu2D) technology, the semiconductor world has been engaged in a Cu2D race. Today, even after~3years of extensive R&D work, the End-of-Line(EOL) yields are still too low to allow the transition of technology to manufacturing. One of the reasons behind this is the myriad of defects associated with Cu technology. Especially, dishing and erosion defects increase the resistance because they decrease the interconnection section area, and ultimately reduce the lifetime of the semiconductor. Methods to reduce dishing & erosion have recently been interface hardness of the pad, optimization of the pattern structure as dummy patterns. Dishing & erosion are initially generated an uneven pressure distribution in the materials. These defects are accelerated by free abrasive and chemical etching. Therefore, it is known that dishing & erosion can be reduced by minimizing the abrasive concentration. Minimizing the abrasive concentration by using Ce$O_2$ is the best solution for reducing dishing & erosion and for removal rate. This paper introduce dishing & erosion generating mechanism and a method for developing a semi-rigid abrasive pad to minimize dishing & erosion during CMP.