Avaliação de processo de folheação em ouro isento de cádmio
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2021-12-15
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Hoehne, Lucélia
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Devido aos danos de saúde e problemas ambientais causados pelos metais cádmio (Cd) e chumbo (Pb) utilizados na produção de joias, semijoias e adornos, vem aumentando o número de pesquisas relacionadas à substituição desses metais. Dentre essas pesquisas, um banho de folheação 18 quilates (K) isento de Cd na composição de sua liga foi proposto, e está sendo usado em algumas empresas. No entanto, é necessário verificar sua eficiência em diferentes peças. Assim, este trabalho realizou a avaliação dos processos de folheação 18K com e sem Cd na composição de sua liga, analisando a resistência à corrosão e a dureza da eletrodeposição do processo de folheação, a fim de compará-los em anéis e pingentes. As peças que foram avaliadas passaram inicialmente pelo processo de preparação da superfície onde foi realizado o tratamento mecânico e químico. Com a superfície preparada para eletrodeposição as peças passaram pelos banhos de cobre (Cu) alcalino, Cu ácido, níquel (Ni), pré-ouro (Au), folheação e cor final. No processo de folheação 18K foi realizada a deposição de 7 e 15 milésimos de Au em anéis e pingentes onde metade das amostras foram folheadas pelo processo com Cd em sua liga e a outra metade foram folheadas pelo processo isento de Cd. A avaliação foi realizada por análises de resistência a corrosão através dos métodos de névoa salina, de imersão em uma solução corrosiva e de sudorese, já a análise de dureza foi realizadas através do método de durômetro de lápis Wilburn e a resistência à abrasividade foi avaliada através de testes tribológicos. Após a finalização dos testes, as peças passaram por uma avaliação por lente de aumento para melhor visualização dos danos causados, facilitando a comparação. Além disso, avaliou-se o custo dos processos realizando orçamentos com empresas que fornecem os processos. Os resultados obtidos mostram que a resistência à corrosão de ambos processos de folheação são equivalentes e que o processo isento de Cd possui menor resistência a abrasividade, porém os resultados foram aceitáveis. Porém o custo do investimento da empresa, para a montagem do processo isento de Cd é 5,76 vezes maior que o custo do processo tradicional. Dessa forma, o processo de folheação de Au isento de Cd está apto a ser utilizado pela indústria a fim de atender a portaria n° 123 do INMETRO.
Due to the environmental problems caused by cadmium (Cd) and lead (Pb) (metals) used in the production of jewelry, semi-jewels and adornments, the number of researches related to the replacement of these metals has been increasing. Among the researches an 18 K cadmium-free plating bath was developed, however it’s necessary to check its efficiency on different pieces. Therefore, this work carried out the evaluation of 18K plating processes with and without Cd in the composition of the alloy, analyzing the corrosion resistance and hardness of the electrodeposition from the plating process in order to compare them on rings and pendants. The pieces that were evaluated passed initially throught the surface preparation process Where the mechanical and Chemical treatment was carried out. With the surface prepared for the electrodeposition, the pieces passed through copper (Cu) alkaline, Cu acid, nickel (Ni) and gilding. In the 18K plating process, 7 and 15 thousandths was deposited in rings and pendants, where half ps the samples were be plated with process with Cd in it’s alloy and the other half were be plated by the Cd-free process. The evaluation was carried out by corrosion resistence tests through the salt spray, immersion in a corrosive solution and sweating methods, while the hardness analysis was carried out through the Wilburn pencil durometer method and the abrasion resistence was evaluated throught of tribological test. After finish the tests, the pieces underwent na evaluation throught a magnifying glass fo better visualization of the damage caused, making it easier a compison. Moreover, the cost of the processes was evaluated by making budgets with companies that supply the processesThe results obtained were that the corrosion resistance of both plating processes are equivalente and that the Cd-free process has less resistance to abrasion, but the results were acceptable. However, the company’s investment cost for assembling the Cd-free process is 5,76 bigger than cost of the raditional process. Thus, the Cd-free Au plating process is able to be used by the industry in order to comply with INMETRO Ordinance N° 123.
Due to the environmental problems caused by cadmium (Cd) and lead (Pb) (metals) used in the production of jewelry, semi-jewels and adornments, the number of researches related to the replacement of these metals has been increasing. Among the researches an 18 K cadmium-free plating bath was developed, however it’s necessary to check its efficiency on different pieces. Therefore, this work carried out the evaluation of 18K plating processes with and without Cd in the composition of the alloy, analyzing the corrosion resistance and hardness of the electrodeposition from the plating process in order to compare them on rings and pendants. The pieces that were evaluated passed initially throught the surface preparation process Where the mechanical and Chemical treatment was carried out. With the surface prepared for the electrodeposition, the pieces passed through copper (Cu) alkaline, Cu acid, nickel (Ni) and gilding. In the 18K plating process, 7 and 15 thousandths was deposited in rings and pendants, where half ps the samples were be plated with process with Cd in it’s alloy and the other half were be plated by the Cd-free process. The evaluation was carried out by corrosion resistence tests through the salt spray, immersion in a corrosive solution and sweating methods, while the hardness analysis was carried out through the Wilburn pencil durometer method and the abrasion resistence was evaluated throught of tribological test. After finish the tests, the pieces underwent na evaluation throught a magnifying glass fo better visualization of the damage caused, making it easier a compison. Moreover, the cost of the processes was evaluated by making budgets with companies that supply the processesThe results obtained were that the corrosion resistance of both plating processes are equivalente and that the Cd-free process has less resistance to abrasion, but the results were acceptable. However, the company’s investment cost for assembling the Cd-free process is 5,76 bigger than cost of the raditional process. Thus, the Cd-free Au plating process is able to be used by the industry in order to comply with INMETRO Ordinance N° 123.
Descrição
Palavras-chave
Cádmio; Corrosão; Dureza; Eletrodeposição; Folheação; Galvanoplastia; Cadmium; Corrosion; Hardness; Electrodeposition; Plating; Electroplating
Citação
ANDRIGHI, Nicolas. Avaliação de processo de folheação em ouro isento de cádmio. 2021. Monografia (Graduação em Engenharia Química) – Universidade do Vale do Taquari - Univates, Lajeado, 08 dez. 2021. Disponível em: http://hdl.handle.net/10737/3333.