EFEITO DA CONCENTRAÇÃO DE NITROGÊNIO DO PLASMA NA FORMAÇÃO DA CAMADA DE DIFUSÃO E DE COMPOSTOS EM AÇO AISI 4140

por: Eduardo Martins, Kassia Escher, Cristaino Brunetti, Paulo César Borges, euclides alexandre bernardelli

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Ano: 2019

Instituições de ensino: Universidade Tecnológica Federal do Paraná, Universidade Tecnológica Federal do Paraná, Instituto Federal do Paraná, Universidade Tecnológica Federal do Paraná, Universidade Tecnológica Federal do Paraná

Idioma: Portugues

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Resumo

The objective of this work was to evaluate the effect of the variation of the nitrogen concentration during the plasma nitriding cycle in the formation of the diffusion layer and compounds layer. The nitrogen concentration was controlled by altering the nitrogen percentage of the gas flow, with two reference conditions with constant nitrogen concentration: NC5 - 5% N2: 75% H2: 20% Ar, NC75 - 75% N2: 5% H2: 20% Ar for 120 min; and three conditions with variation of the nitrogen concentration during the nitriding cycle: NV1 - 5% N2: 75% H2: 20% Ar ? 20% N2: 60% H2: 20% Ar ? 5% N2: 75% H2: 20 % Air, times 40:40:40 min, NV2 - 75% N2: 5% H2: 20% Ar ? 50% N2: 30% H2: 20% Ar? 25% N2: 55% H2: 20% Ar ? 2% N2: 75% H2: 20% Ar, times 10: 10: 10: 90 min, respectively and; NV3 - 20% N2: 60% H2: 20% Ar ? 80% H2: 20% Ar, time of 2:18 min, respectively, being repeated up to the total time of 120 min. The results show that nitriding with constant concentration of nitrogen (NC75) favors the formation of the compounds layer, having predominant formation of the ? (Fe2-3N) phase, and that using the condition NV2 can control the formation of ? and ?' phases, the compound layer being predominantly formed by the ?' phase (Fe4N) and that in the NV3 condition there was only formation of the diffusion layer. It can be concluded that controlling the concentration of nitrogen during nitriding can control the formation of the compounds and diffusion layers, as to thickness, hardness and phases.


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