Abstract
The biocompatibility of materials in contact with a living tissue becomes a puzzle in the overall picture of assessing the toxic effects of chemicals that come into contact with us. Allergic reactions to substances are a significant and growing health problem affecting large parts of the population in Europe. Wristwatches are objects worn in prolonged contact with the skin, being subject to localized corrosion, especially pitting and crevice types, in sulfide-chloride medium, and high wear in the bracelets joints. Watches of medium quality are usually made of stainless steels. The X2 CrNiMo 17-12-2 316L grade as well as X1 CrNiMo 20-25-5 Cu 1 or 904L are commonly used, having good resistance to generalized corrosion. The passive layer is nevertheless insufficient to ensure complete immunity in all cases of localized corrosion encountered during wear. For this reason, a high-corrosion-resistant steel: X1 CrNiMo 18-15-4 N 0.15 or 317LMN, from three different suppliers was evaluated. Metallographic characterization was carried out. The corrosion behavior evaluation was performed for the generalized corrosion, pitting and crevice corrosion and galvanic corrosion. Galvanic couples steel 317LMN-gold 18K alloy 3N and gold 18K 5M were used. The results of the generalized and pitting corrosion test indicated three basic groups. All of the 317LMNs were similar. The 316L variants tested noticeably worse. The 904Ls were difficult to discern, but certainly easier than the 316Ls and, possibly, at least comparable to the 317LMNs.
Highlights
Since 2006, Europe has a new vision regarding chemicals toxicology to humans, because of the REACH regulation [1,2]. the biocompatibility of materials in contact with a living tissue becomes a puzzle in the overall picture evaluating the effects of chemicals toxicity that come into contact with us [3,4,5].ECHA (European Chemical Agency) [6] has developed a plan for the implementation of the substances of very high concern (SVHC) [7], namely endocrine disruptors (ED), carcinogens, mutagens, toxics for reproduction (CMR), and sensitizers
Among the SVHC substances incriminated by ECHA, the most frequent
Electrochemical evaluation of the generalized corrosion by the technique of the rotating electrode [30] and taking into account, for evaluation, the American Society for Testing and Materials ASTM G3-89 [31] and ASTM G59-97 [32] standards; pitting and crevice corrosion according to the ASTM F746-04 [33] standard; galvanic corrosion [34] taking into account the mixed potential theory [35]
Summary
Since 2006, Europe has a new vision regarding chemicals toxicology to humans, because of the REACH regulation (registration, evaluation, authorization, and restriction of chemicals) [1,2]. Our study is limited to metal materials (steel) supposed to be used in the manufacture of articles which come in prolonged contact with the skin, specific to watchmaking, such as bracelets, watchcases, etc. Steels are sensitive to pitting and crevice corrosion, especially the 316L type [23,24] For these reason, another alloy, X1 CrNiMo 18-15-4 N. It forms a passive layer due to the presence of nitrogen in its composition [25] It is developed by vacuum fusion and remelted, which gives it high inclusion cleanliness and reduces the risk of pitting. This alloy is suitable for use in highly aggressive media where it may be subject to wear
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