• Restorative Dentistry and Endodontics
• /
• 제10권1호
• /
• pp.63-70
• /
• 1984

It was the purpose of this study to determine the galvanic current between a gold alloy inlay and four types of amalgam using the circuit through pulp chambers when the freshly extracted teeth with those restorations were brought into contact in a physiologic saline solution, and to investigate the effectiveness of cavity varnish or ammonated silver-nitrate on the surface of amalgam restoration in reducing galvanic current. The current was measured with current-to-voltage converter and recored on a physiograph 6630-257. The following results were obtained. 1. Generally, galvanic current decreased as the time elapsed. 2. Galvainc current decreased significantly in the first day and after then minimal change was observed until 30th day. 3. Initial galvanic current was 29.6 ${\mu}A$ in the cut amalgam and 24.5 ${\mu}A$ in Dispersalloy amalgam and after then the current was significantly decreased. 4. Initial galvanic current was 12.6 ${\mu}A$ in spherical amalgam (low copper amalgam) and 13.8 ${\mu}A$ in Tytin amalgam and the amount of change was lower in sperical amalgam and Tytin amalgam than that in lathe cut amalgam and Dispersalloy amalgam. 5. Painting ammoniated silver-nitrate or Copalite on the surface of amalgam resotration decreased initial galvanic current and ammoniated silver-nitrate is more effective in decreasing galvanic current than Copalite. 6. Galvanic current by contact between amalgam restoration and gold restoration increased abruptly and dropped rapidly becoming almost.

• Corrosion Science and Technology
• /
• 제4권3호
• /
• pp.75-80
• /
• 2005

This work dealt with the evaluation of galvanic corrosion rate in a corrosion cell having annular gap of 0.5 mm between carbon steel 1018 and alloy 600 as a function of temperature and boron concentration. Temperature and boron concentration were ranged from 110 to 300 $^{\circ}C$ and 2000~10000 ppm, respectively. After the operating temperature of the corrosion cell where the electrolyte was injected was attained at setting temperature, galvanic coupling was made and at the same time galvanic current was measured. The galvanic corrosion rate decreased with time, which was described by corrosion product such as protective film as well as boric acid deposit formed on the carbon steel with time. From the galvanic current obtained as a function of temperature and boron concentration, it was found that the galvanic corrosion rate decreased with temperaturewhilethe corrosionrate increasedwith boronconcentration. The experimental resultsobtained from galvanic corrosion measurement were explained by adhesive property of corrosion product such as protective film, boric acid deposit formed on the carbon steel wall and dehydration of boric acid to be slightlysolubleboric acid phase.Moreoverthe galvaniccorrosionrate calculatedusing initialgalvaniccoupling current instead of steady state coupling current was remarked, which could give us relatively closer galvanic corrosion rate to real pressurized water reactor.

• Restorative Dentistry and Endodontics
• /
• 제18권2호
• /
• pp.469-481
• /
• 1993

The purpose of this study was to achieve the reduction of the galvanic current between the dental amalgam alloy and gold alloy. In order to measure the galvanic current between these two metals a prep in the size of $4{\times}13mm$ which was filled with amalgam and another prep of $4{\times}2mm$ was filled with gold alloy was made in the acrylic resin. These two preps were then connected to a 2mm diameter copper wire. Using an ammeter to measure the galvanic current, six different kinds of amalgam and gold alloy were immersed in saline solution with approximately 10mm distance between the two alloys. Chemical agents that are thought to reduce the galvanic current such as hydrazine. silver nitrate, potassium chromate, and bonding agents such as Scotch bond 2(3M) and All bond 2(Bisco) were applied to the alloy surface. Cathodic inhibitor such as hydrazine was applied to gold alloy where as anodic inhibitor such as silver nitrate and potassium chromate were applied to amalgam. Both bonding agents, Scotch bond 2(3M) and All bond 2 (Bisco), were applied to amalgam. The following results were obtained when the currency on the coated alloy surface was compared to the uncoated surface. 1. The galvanic currency went down as the time elapsed and after 30 minutes no change was detected. 2. Initial currency was higher in low copper amalgam compared to high copper amalgam. Intitial currency was the highest in low copper lathe-cut amalgam. 3. Group of gold coated with hydrazine had the most reduction in galvanic currency. 4. Group of amalgam coated with silver nitrate or potassium chromate also showed significant reduction in galvanic currency. 5. The bonding agents also helped reduce galvanic currency. 6. Of all the agents used to reduce galvanic currency, silver nitrate showed the best result.

• Corrosion Science and Technology
• /
• 제8권1호
• /
• pp.27-39
• /
• 2009

Non metallic composite materials, for example, GECM(graphite epoxy composite material) show high specific strength because of low density. These kinds of non metallic composite materials improved the structural effectiveness and operation economics. However, if these materials contacted several metals, corrosion can be arisen since non metallic composite materials have electrical conductivity. This paper dealt with galvanic corrosion between graphite epoxy composite material and several metals. Base on the electrochemical galvanic corrosion test between GECM and metals, corrosion current of carbon steel and aluminium increased with time but corrosion current of stainless steels and titanium decreased and galvanic potential increased. This behavior shows the galvanic corrosion depends upon the presence of passive film. Also, galvanic effect of GECM coupled with ferrous alloys and non-ferrous alloys was lower than that of 100% graphite, which is attributed to lower exposed area of graphite fiber in the GECM than apparent area of the GECM specimen used for the calculation of galvanic current in this work.

• Corrosion Science and Technology
• /
• 제16권3호
• /
• pp.128-140
• /
• 2017

Aluminum alloy matrix may be used for manufacturing lighter automobiles. However, galvanic corrosion may occur between the rivet joint combining aluminum alloy matrix and a CFRP (carbon fiber reinforced plastic) laminate. The possibility of galvanic corrosion may be investigated by measuring galvanic couple currents. Two types of galvanic current measuring methods were used. One method is to use potentiodynamic polarization curves and the other is the ZRA (zero resistance ammeter) method. For galvanic corrosion experiments graphite, a major component of CFRP, was used with carbon steel (rivets) and 6061 aluminum alloys. Regardless of carbon steel, Ni deposited carbon steel, and 316L stainless steels we also investigated the possibility of reduction in galvanic corrosion. Results revealed that even though Ni deposited carbon steel or 316L stainless rivet may slightly increase galvanic current density between those and Al matrix, substitute rivets for carbon steel may be considerably useful for reducing overall galvanic corrosion.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
• /
• pp.269-272
• /
• 2000

The flow accelerated galvanic corrosion characteristics of a carbon steel coupled to stainless steel were investigated in deaerated alkaline-chloride solutions as a function of flow velocities(0, 0.2, 0.4 and 0.6 m/s), pH(8, 9, and 10) and temperature(25, 50 and $75^{\circ}C$). The electrochemical properties of specimens were investigated by potentiodynamic test and galvanic corrosion test using RCE(Rotating Cylinder Electrode). Carbon steel did not show passive behavior in the alkaline-chloride solution. The galvanic current density increases with increasing flow velocity and temperature, but decreased with increasing pH. Flow velocity had a small effect on the galvanic current density at $25^{\circ}C$, whereas the flow velocity increased galvanic current density significantly at $50^{\circ}C$ and $75^{\circ}C$. This might be due to the increased solubility of magnetite at the higher temperature.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2012년도 춘계학술발표회 논문집
• /
• pp.280-280
• /
• 2012

Mg의 첨가한 Zn-Mg-Al 합금도금강판에 형성된 $Zn-MgZn_2$ 공정조직의 부식거동을 이해하고자 진공 고주파 용해로 $MgZn_2$ 제작한 후 Zn와 galvanic coupling하여 $MgZn_2$합금과 Zn간의 galvanic corrosion 거동을 알아보았다. $MgZn_2-Zn$ galvanic coupling의 SVET 결과에서 $MgZn_2$가 anode, Zn가 cathode가 됨을 확인되었다. $MgZn_2$의 Zn와의 galvanic corrosion 평가에서 galvanic current는 Zn 보다 낮은 potential에서 anodic current density를 나타내었으며, galvanic potential은 $MgZn_2$전위로부터 두 합금의 혼합전위를 향해 증가함을 알 수 있었다. Zn-Mg-Al 합금도금강판의 염수분무 평가에서도 초기 $Zn-MgZn_2$ 공정조직에서 $MgZn_2$가 용출되는 것이 관찰되었다.

• 한국멀티미디어학회논문지
• /
• 제21권12호
• /
• pp.1379-1386
• /
• 2018

In this paper, we proposed eyeglass type periorbital wrinkle treatment device for reducing and improving periorbital wrinkles using near infrared LED of 850nm wavelength and galvanic current. The proposed periorbital wrinkle treatment device is equipped with a control system based on F-PCB. It consists of eight near-infrared LEDs and four indicator LEDs for treatment of right and left periorbital wrinkles. The eyeglass frame is coated with conductive material, so galvanic current can flow to the skin of periorbital wrinkle contacted to it. One male adult in the mid-40s was allowed to use the device for 10 minutes every day for 4 weeks. After 4 weeks, image analysis using optical equipment for measuring wrinkles indicated that wrinkle indexes were reduced.

• Journal of Advanced Research in Ocean Engineering
• /
• 제2권4호
• /
• pp.158-168
• /
• 2016

During the installation of crude oil or gas pipelines, which pass through onshore buried pipelines or onshore pipeline from subsea pipeline to onshore plant, countermeasures need to be implemented so as to ensure a sufficient design life by protecting the steel pipes against corrosion. This can be achieved through impressed current cathodic protection method for onshore pipelines and through galvanic sacrificial anode corrosion protection method for offshore pipelines. In particular, in the case of impressed current cathodic protection, isolation joint flanges should be used. However, this makes maintenance control difficult with its installation having a negative impact on price. Therefore, in this study, the most suitable methodology for onshore pipeline protection between galvanic sacrificial anode corrosion protection and impressed current cathodic protection method will be introduced. In oil and gas transportation facilities, the media can be carried to the end users via onshore buried and/or offshore pipeline. It is imperative for the field operators, pipeline engineers, and designers to be corrosion conscious as the pipelines would undergo material degradations due to corrosion. The mitigation can be achieved with the introduction of an impressed current cathodic protection method for onshore buried pipelines and a galvanic sacrificial anode corrosion protection method for offshore pipelines. In the case of impressed current cathodic protection, isolation joint flanges should be used to discontinuity. However, this makes maintenance control to be difficult when its installation has a negative impact on the price. In this study, the most suitable corrosion protection technique between galvanic sacrificial anode corrosion protection and impressed current cathodic protection is introduced for (economic life of) onshore buried pipeline.

• Corrosion Science and Technology
• /
• 제16권4호
• /
• pp.183-186
• /
• 2017

Galvanic corrosion tests of Zn/steel couples were conducted in 1 M NaCl and $1M\;MgCl_2$ solutions to investigate the impact of magnesium ion on corrosion behavior of the couples. Two types of Zn/steel couples were used for measurements of open circuit potential (OCP) and galvanic current. From the results of OCP transient of Zn/steel couples, the corrosion potential in $1M\;MgCl_2$ was a more positive value than that in 1 M NaCl during the sacrificial dissolution of Zn. However, earlier increase of OCP of the couples in $1M\;MgCl_2$ solution indicates that the sacrificial dissolution rate of Zn in $1M\;MgCl_2$ was enhanced more than that in 1 M NaCl, agreeing with the results on transients of galvanic current. This result is due to that cathodic reaction on the steel surface of the Zn/steel couple was enhanced in $1M\;MgCl_2$ by the occurrence of hydrogen evolution reaction.