• Journal of Electrochemical Science and Technology
• /
• v.9 no.1
• /
• pp.44-50
• /
• 2018

The aims of this study were to determine the corrosion behavior of pure copper in the presence of Desulfovibrio sp. and also to investigate the effects of glutaraldehyde (GD) and isothiazolinone (ISO) on the corrosion behavior of pure copper in the presence of this sulfate-reducing bacteria (SRB) strain by using electrochemical techniques. Electrochemical measurements of pure copper were carried out at specified time intervals (0, 8, 24, 48, and 96 hr) over a period of exposure. Corrosion rates of pure copper from anodic and cathodic Tafel slopes and corrosion potential ($E_{corr}$) were determined. Biofilm and corrosion products on the copper surfaces were observed by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray Spectrometry (EDS) analyses. The effects of solution types (PC (Postgate's C medium) and SRB (Desulfovibrio sp.)) and exposure times of copper and biocides (ISO or GD) on the corrosion rates of pure copper were evaluated by statistical analyses. As a result of the FESEM analysis, biofilm formation was observed on the surfaces of pure copper exposed to the Desulfovibrio sp. cultures both with and without the biocides. The results show that the pure copper was corroded by Desulfovibrio sp. However, the addition of GD or ISO to the Desulfovibrio sp. culture resulted in a decrease in the corrosion rate of the pure copper. It was also observed that both of the biocides showed a similar effect on pure copper's corrosion rate caused by Desulfovibrio sp.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.1640-1644
• /
• 2006

The first issue that should be overcome in copper process is its poor adhesive strength between pure copper film and glass substrate. In this study, defining the adhesive strength of pure copper film on various substrates and clarifying the key deposition parameters are presented for the investigation of copper process. First, using different kinds of surface plasma treatments were studied and the results showed that the adhesive strength was not improved even though the roughness of glass substrate surface was increased. Second, adding an adhesive layer between glass substrate and pure copper film was used to enhance the adhesion. Based on the data in the present paper, adopting copper alloy film as an adhesive layer can have capability preventing peeling problem in copper process. Besides, Cu/Cu alloy structure could be etched with the same etchant with better taper angle than the one with single layer of Cu. Unlike Cu/Mo structure, there is no residual problem for Cu/Cu alloy structure during etching process. Finally, this structure was examined in electrical test without significant difference in comparison with the conventional metal process.

• Journal of the Korean Society of Safety
• /
• v.14 no.1
• /
• pp.86-92
• /
• 1999

This study was carried out to investigate the effect of chemical cleaning of corrosion product on cooling system made of copper as a basic material and using cooling water as pure water. We studied chemical cleaning condition that minimizes the influence on basic material by means of EDTA solution so as to eliminate the slurry in cooling system. In addition, the proper amount of NALCO-39L (Nitrite-Borate-BZT mixture) as a inhibitor was determined in order to protect the copper in cooling system against corrosion after chemical cleaning and the effect of corrosion resistance on the copper surface treated was excelent in comparison with surface untreated. As a result, we found that the main components of sludge in cooling system produced by corrosion of copper were $Cu_2O$, CuO, Cu, and Fe. The optimum condition of chemical cleaning was 400ppm EDTA solution at $60^{\circ}C$. Inhibitor concentration needed to treat the surface of pure copper was 15～20ppm per unit area and corrosion rate of copper treated with 500ppm inhibitor solution for 72 hrs at $60^{\circ}C$ was remarkably decreased as compared with that of pure copper.

• Journal of the Korean Society for Heat Treatment
• /
• v.33 no.4
• /
• pp.185-192
• /
• 2020

In this study, materials characterization of pure copper and copper based carbon nano-tube composite prepared by powder metallurgy method were investigated. Prior to evaluate materials characterization, spark plasma sintering processing variables such as sintering temperature, pressure, thickness and diameter of compacts was optimized to ensure the microstructure and materials property of pure Cu and Cu-CNT composite. In addition, corrosion behavior of Cu-based CNT composite produced by powder sintering method was investigated. It was confirmed from this study that the corroded surfaces of the composite shows less dissolution compared with pure copper in 3.5 wt% NaCl solution. The measured corrosion current density (I_corr) indicates improved corrosion property of Cu based composite containing small additions of CNTs in chloride containing media. Micro-galvanic activity between Cu and CNT was not observed in given sintering condition.

• Journal of Korea Foundry Society
• /
• v.14 no.6
• /
• pp.558-565
• /
• 1994

The horizontal continuous casting process with the heated mold was applied to obtain the unidirectionally solidified rods($4{\sim}8mm$ dia.) of pure copper with good surface quality. The results could be summarized as follows. 1. The unidirectional solidification of pure copper rods with good surface(mirror surface) quality could be obtained by placing the S/L interface inside the heated mold cavity even though the cast copper rods were covered with thin copper oxide layer. 2. The casting speed for 4mm dia. rods with mirror surfaces was affected significantly by the mold-cooler distance rather than the cooling flow rate when other casting conditions were fixed. 3. The casting speed was the main factor affecting the oxidation of copper during the continuous casting and the thickness of copper oxide layer decreased almost linearly as the casting speed increased.

• Corrosion Science and Technology
• /
• v.15 no.6
• /
• pp.311-313
• /
• 2016

The anodic dissolution behavior of copper and brass in an electrolyte solution of 0.5M NaCl containing 0.5 mM $NaHCO_3$ was investigated by electrochemical impedance spectroscopy. The Nyquist plots of the copper impedance described a small loop in the high-frequency range and a large locus in the low-frequency range. Additionally, the features of the impedance spectrum of the brass were similar to those of the copper. This indicates that the copper-enriched layer formed on the brass surface due to the selective dissolution of the zinc from the surface. In addition, the rest potential and the anodic polarization curve for each sample were measured in order to discuss the selective dissolution of the zinc from the brass surface.

• Proceedings of the KSME Conference
• /
• 2001.06a
• /
• pp.495-500
• /
• 2001

The significant creep in copper takes place at relatively low temperature and applied stress. Thus the study on modeling of creep behavior using the copper should provide researchers with benefits such as time for the test. In this study, a test of creep crack growth regarding copper was performed at 400 and $500^{\circ}C$, and analyzed. As result, the crack growth rate at $500^{\circ}C$ turned out to be 10 times higher than that at $400^{\circ}C$ in terms of $C^*$, while the crack growth rate at $500^{\circ}C$ was several hundreds times higher than that at $400^{\circ}C$ in terms of K. Moreover, a linear relationship between the crack growth rate and $C^*$ at the same temperature was established.

• Journal of Sensor Science and Technology
• /
• v.23 no.4
• /
• pp.234-237
• /
• 2014

In this paper, a copper foil-thick grapheme (thin graphite sheet)-copper foil structure is reported to achieve mechanically strong and high thermal conductive layer suitable for heat spreading components. Since graphene provides much higher thermal conductivity than copper, thick graphene embedded copper layer can achieve higher effective thermal conductivity which is proportional to graphene/copper thickness ratio. Since copper is nonreactive with carbon material which is graphene, chromium is used as adhesion layer to achieve copper-thick graphene-copper bonding for graphene embedded copper layer. Both sides of thick graphene were coated with chromium as an adhesion layer followed by copper by sputtering. The copper foil was bonded to sputtered copper layer on thick graphene. Angstrom's method was used to measure the thermal conductivity of fabricated copper-thick graphene-copper structure. The thermal conductivity of the copper-thick graphene-copper structures is measured as $686W/m{\cdot}K$ which is 1.6 times higher than thermal conductivity of pure copper.

• Proceedings of the KWS Conference
• /
• 2000.10a
• /
• pp.192-195
• /
• 2000

This paper describes a fundamental investigation of the friction welding condition for pure copper/pure titanium and the effect of friction time, upset pressure on the mechanical and metallurgical properties of friction welding. Under the constant upset pressure, the tensile strength make a little difference with an increase in friction time. At the constant friction time, the tensile strength increased with an increase in upset pressure. The tensile fracture of Cu to Ti joint occurred in Cu base material near interface.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.430.1-430.1
• /
• 2016

We present the concept of reducible fugitive material that conformally surrounds core Cu nanowire (NW) to fabricate transparent conducting electrode (TCE). Reducing atmosphere can corrodes/erodes the underlying/surrounding layers and might cause undesirable reactions such impurity doing and contamination, so that hydrogen-/forming gas based annealing is impractical to make device. In this regards, we introduce novel reducible shell conformally surrounding indivial CuNW to provide a protection against the oxidation when exposed to both air and solvent. Uniform copper lactate shell formation is readily achievable by injecting lactic acid to the CuNW dispersion as the acid reacts with the surface oxide/hydroxide or pure copper. Cu lactate shell prevents the core CuNW from the oxidation during the storage and/or film formation, so that the core-shell CuNW maintains without signficant oxidation for long time. Upon simple thermal annealing under vacuum or in nitrogen atmosphere, the Cu lactate shell is easily decomposed to pure Cu, providing an effective way to produce pure CuNW network TCE with typically sheet resistance of $19.8{\Omega}/sq$ and optical transmittance of 85.5% at 550 nm. Our reducible copper lactate core-shell Cu nanowires have the great advantage in fabrication of device such as composite transparent electrodes or solar cells.