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PRODUCTS FINISHING — PFonline.com 17 • Finally, heat develops around a defective welding spot. The result is premature wear. As long as these construction recommendations are followed, you will create the "perfect anode" for hard chrome plating, with Pt/Ti or Pt/Nb models. Dimensionally stable models are more expensive in the investment phase than lead anodes. But when costs are considered in more detail, titanium models with a platinum surface could be an inter- esting alternative for hard chrome plating. This is explained by a comprehensive and thorough analysis of total costs for conventional lead anodes and platinum anodes. Eight lead alloy anodes made from PbSn 7 , with a length of 1,700 mm and a diameter of 40 mm, were compared with the appropriately dimensioned Pt/Ti anodes for chrome plating a cylindrical component. Manufacturing costs for the eight lead anodes came to around 1,400 euros ($1,471), which seems cheap at first glance. The investment required to develop the necessary Pt/ Ti anodes is considerably higher. This came to around 7,000 euros for the initial purchase. The platinum coating is especially costly. The pure precious metals alone make up 45 percent of this amount. The platinum coating of 2.5 μm requires 11.3 g of the precious metal for each of the eight anodes. At a price of 35 euros per gram, this makes 3,160 euros. Minimize Production Downtime Even though lead anodes seem the better choice, this changes quickly on closer inspection. After just three years, the total cost for the lead anodes is considerably higher than for the Pt/Ti models. In the conser- vative example calculation, a typical application flow density of 40 A/dm 2 is assumed. In the result, there is a power flow of 6,720 amperes for the given anode surface of 168 dm 2 during a running time of 6,700 hours in three years. This corresponds to 10 hours of net operational time on roughly 220 working days per year. The platinum layer thickness decreases slowly because of platinum oxidation going into solution. In the example, this was taken into account as 2 grams per 1 million ampere hours. There are many reasons behind the cost benefits of Pt/ Ti in comparison with lead anodes. Most importantly, the reduced electricity usage (minus 14,800 kWh/year at a price of 0.14 euro/kWh) costs around 2,000 euro per year. Additionally, the roughly 500 euros in yearly disposal costs for lead chromate sludge and 1,000 euros for maintenance and production downtime are no longer required— and this was very conservatively calculated. Total costs for lead anodes over three years came to 14,400 euros ($15,130). For Pt/Ti anodes, costs were 12,020 euros— including re-platinization. Even if the costs for maintenance and production downtime (1,000 euros for one day per year) weren't accounted for, the break-even point would still be reached after three years. From this time on, the gap between the two widens further, in favor of the Pt/Ti anodes. Many branches take advantage of the various benefits of high-temperature electrolyzed platinized anodes. Manufacturers in the lighting, semi-conductor and PCB, automotive, hydraulics, mining machinery, waterworks and swimming pool industries all rely on these coating technolo- gies. More applications will surely be developed in the future, as sustainable cost considerations and environmental protec- tion are long-term concerns. Therefore, lead may face even more critical scrutiny. The original text was published in German in Annual Surface Technology (Volume 71, 2015), edited by Professor Timo Sörgel, University of Applied Science, Aalen/Germany. Courtesy of Eugen G. Leuze Verlag, Bad Saulgau/Germany. Fig. 5: Beaker anodes for coating sample parts and isolation attempts on a laboratory-scale basis. Fig. 4: The mesh width on the expanded metal mesh anodes can be adapted. The mesh allows for increased electrolytic circulation and better gas removal. L = LWD B = Feed A = Thickness W = SWD TITANIUM VS. LEAD ANODES