Obtenção de revestimentos dúplex por nitretação a plasma e PVD-TiN em aços ferramenta AISI D2 e AISI H13. / Duplex coatings on AISI H13 and AISI D2 tool steels by using plasma nitriding and TiN-PVD.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

In this work, the influence of both the microstructure and the load-bearing capacity of nitrided layers, formed on top of AISI D2 and AISI H13 tool steels, on adhesion and wear resistance of PVD-TiN coatings was studied. The threshold nitriding potential curves for the above mentioned steels and the optimum conditions of the pre-treatments which increased the adhesion as well as the wear resistance of the PVD-TiN were determined experimentally. By using longer nitriding times (about 11 h) and lower nitrogen contents in the gas mixture (about N2-5%vol.), it was possible to minimize the pile-up degree of the TiN/H13 nitrided substrates and, consequently, the occurrence of coatings chipping. This flaw persists when the nitrided layer is thin, due to an abrupt transition of mechanical properties at the TiN coating / steel core interface. Shorter nitriding times (about 42 min.) and lower nitrogen contents (about N2-5%vol.), on the other hand, are sufficient to guarantee a better adhesion of TiN coatings on AISI D2 tool steel, as the core of such steel possesses relatively better load-bearing capacity than the AISI H13 tool steel. The presence of a black layer at the TiN/nitrided layer interface was observed in all coatings deposited over nitrided layers produced above the threshold nitriding potential curves. This layer affects adversely the wear resistance and the adhesion of the TiN coatings. When higher loads are applied on the coated surface, “egg shell” type flaws easily occur.

ASSUNTO(S)

hardness micro-scale abrasive wear cold and hot working tool steels duplex treatments elastic modulus electrical arc discharge vaporation plasma assisted physical vapour deposition plasma nitriding revestimentos para aplicações em tribologia tribologycal coatings aderência ensaio estático de indentação módulo de elasticidade depth-sensing indentation filmes de tin materiais para usinagem intermitente resistência a abrasão interrupted-cut machining nitretação a plasma pvd aços ferramenta aisi h13 e aisi d2 dureza nanoindentação papvd threshold nitriding potential deposição física na fase vapor evaporação assistida por arco elétrico desgaste abrasivo surface engineering curvas de início de formação de camada branca engenharia de superfície in situ heterogeneous precipitation of crn tratamentos dúplex microabrasão precipitação heterogênea in situ de crn rockwell-c adhesion test

ACESSO AO ARTIGO

Documentos Relacionados