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<p>[QUOTE="mlov43, post: 3920399, member: 16729"]The first images below are what the current (2006~present) South Korean 10-Won coin looks like. It's the smallest-value circulating coin in the country.</p><p><br /></p><p>In exchange rate, it's equivalent to 8/10ths of a U.S. Cent, or .92 Japanese Yen. It still costs 30 won to make this "new" 10 won coin (ugh!), but it was also considered to be about 20 won cheaper than the cost of manufacturing an old 10 won coin, which was 65%Cu-35%Zn in composition.</p><p><br /></p><p>The 10-Won coin is 18mm in diameter, 48% Cu (outer layer) and 52% Aluminum (core). I believe this is the first South Korean clad coin. The Koreans claim it's the world's first such copper-coated aluminum coin, or the first manufactured in this way.</p><p><br /></p><p>[ATTACH=full]1033355[/ATTACH]</p><p><br /></p><p>A zoomed-in edge-view:[ATTACH=full]1033357[/ATTACH]</p><p><br /></p><p>Below are images of this 10-Won coin after submersion in water or run through a clothes washer.</p><p><br /></p><p>Reports in Korea say that the two metals (copper and aluminum) are in direct contact with each other by pressing copper on aluminum. In this case, a so-called 'galvanic corrosion phenomenon' occurs in which an electrolyte such as water accelerates the corrosion. At South Korea's Incheon International Airport, there is a fountain which contains coins from all over the world, and Korean reporters found these 10-Won coins there all corroded as bubbles were rising around the outside of them as they lay in the fountain. They claim that the copper on the surface can easily fall off and become unacceptable as money.</p><p><br /></p><p>Here's an explanation being bandied about in the Korean blogosphere:</p><p><br /></p><p> <i>"...both copper and aluminum are very vulnerable to '<b>chloric acid</b>'. Chloric acid may be unfamiliar, but it is a component of our common laundry detergent and pool water. In fact, a simple experiment showed that the new 10-won coin quickly decays in water with detergent"</i></p><p><i><br /></i></p><p>And another:</p><p><i><br /></i></p><p><i>"[This is] caused by <b>galvanic corrosion</b>, a phenomenon that occurs when two different metals with different ionization tendencies are attached. In particular, the corrosion of aluminum parts is extremely fast, because aluminum is much more ionized than copper, and aluminum is oxidized first instead of copper."</i></p><p><i><br /></i></p><p>First, I'd like to know if the above explanations are true. Perhaps [USER=17261]@BadThad[/USER] or [USER=15199]@desertgem[/USER] can help?</p><p><br /></p><p>Has such phenomena taken place with other coins in the world? Do Zincolns have this problem?</p><p> </p><p>After being in a washing machine, immersion in water, etc:</p><p>[ATTACH=full]1033358[/ATTACH]</p><p>[ATTACH=full]1033359[/ATTACH]</p><p>[ATTACH=full]1033360[/ATTACH][/QUOTE]</p><p><br /></p>
[QUOTE="mlov43, post: 3920399, member: 16729"]The first images below are what the current (2006~present) South Korean 10-Won coin looks like. It's the smallest-value circulating coin in the country. In exchange rate, it's equivalent to 8/10ths of a U.S. Cent, or .92 Japanese Yen. It still costs 30 won to make this "new" 10 won coin (ugh!), but it was also considered to be about 20 won cheaper than the cost of manufacturing an old 10 won coin, which was 65%Cu-35%Zn in composition. The 10-Won coin is 18mm in diameter, 48% Cu (outer layer) and 52% Aluminum (core). I believe this is the first South Korean clad coin. The Koreans claim it's the world's first such copper-coated aluminum coin, or the first manufactured in this way. [ATTACH=full]1033355[/ATTACH] A zoomed-in edge-view:[ATTACH=full]1033357[/ATTACH] Below are images of this 10-Won coin after submersion in water or run through a clothes washer. Reports in Korea say that the two metals (copper and aluminum) are in direct contact with each other by pressing copper on aluminum. In this case, a so-called 'galvanic corrosion phenomenon' occurs in which an electrolyte such as water accelerates the corrosion. At South Korea's Incheon International Airport, there is a fountain which contains coins from all over the world, and Korean reporters found these 10-Won coins there all corroded as bubbles were rising around the outside of them as they lay in the fountain. They claim that the copper on the surface can easily fall off and become unacceptable as money. Here's an explanation being bandied about in the Korean blogosphere: [I]"...both copper and aluminum are very vulnerable to '[B]chloric acid[/B]'. Chloric acid may be unfamiliar, but it is a component of our common laundry detergent and pool water. In fact, a simple experiment showed that the new 10-won coin quickly decays in water with detergent" [/I] And another: [I] "[This is] caused by [B]galvanic corrosion[/B], a phenomenon that occurs when two different metals with different ionization tendencies are attached. In particular, the corrosion of aluminum parts is extremely fast, because aluminum is much more ionized than copper, and aluminum is oxidized first instead of copper." [/I] First, I'd like to know if the above explanations are true. Perhaps [USER=17261]@BadThad[/USER] or [USER=15199]@desertgem[/USER] can help? Has such phenomena taken place with other coins in the world? Do Zincolns have this problem? After being in a washing machine, immersion in water, etc: [ATTACH=full]1033358[/ATTACH] [ATTACH=full]1033359[/ATTACH] [ATTACH=full]1033360[/ATTACH][/QUOTE]
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