Mechanical and tribological features of TaN(Ag-Cu) duplex nanocomposite coatings: their response to heat treatment
2017
espanolSe recubrieron muestras de acero inoxidable martensitico AISI 420 y de silicio (100) con nitruro de tantalio dopado con nanoparticulas de plata y cobre TaN(Ag-Cu) para mejorar su dureza y resistencia al desgaste. Los recubrimientos fueron depositados por la tecnica de la pulverizacion catodica DC asistida por campo magnetico, utilizando un blanco de tantalio confrontado a otro blanco compuesto de plata/ cobre (50/50 %at). Las muestras recubiertas se sometieron a un apropiado ciclo de tratamiento termico a 250 °C durante 8 minutos para lograr una difusion controlada de las nanoparticulas Ag-Cu hacia la superficie del compuesto, ya que sus propiedades mecanicas y tribologicas dependen, no solo del contenido de Ag/Cu, sino tambien del tamano, forma y densidad de las nanoparticulas de Ag-Cu sobre la superficie del TaN (Ag,Cu). Se evaluo la influencia del contenido de Ag-Cu sobre la microestructura, las propiedades mecanicas y tribologicas del compuesto antes y despues del tratamiento termico. En terminos generales la microdureza y la tasa de desgaste aumentan inicialmente con el contenido de Ag/Cu, pero luego disminuyen para contenidos mayores a 0,71%at, exhibiendo el efecto lubricante que ejercen las nanoparticulas de Ag-Cu en el compuesto. El recubrimiento C3 tratado termicamente, presento una microdureza de 15GPa, muy superior a la exhibida por acero inoxidable AISI 420, asi como una tasa de desgaste seis ordenes de magnitud menor que la de dicho acero. EnglishAISI 420 martensitic stainless steel samples and silicon (100) were coated with tantalum nitride doped with copper and silver nanoparticles TaN(Ag-Cu) to improve their hardness and wear resistance. The coatings were deposited by unbalanced DC Magnetron Sputtering technique, using a tantalum target and other silver/copper composite target (50/50%at), confronted each other. The coated samples were subjected to an appropriate heat treatment at 250 °C for 8 minutes to achieve a controlled diffusion of Ag-Cu nanoparticles to the TaN(Ag-Cu) surface. Due to their mechanical and tribological properties depend, not only on the content of Ag-Cu, but also on the size, shape and density of nanoparticles of Ag-Cu on the surface of the coating. The influence of the Ag-Cu content on the microstructure and mechanical and tribological properties of the composite coating were evaluated before and after the heat treatment was evaluated. In general terms, the microhardness and wear rate increased initially with Ag-Cu content, but then dropped down for contents higher to 0.71% at, exhibiting the lubricating effect of Ag-Cu nanoparticles in the compound before and after heat treatment. The heat treated C3 sample showed a microhardness of 15 GPa, very superior to the hardness of AISI 420 stainless steel, as well as a wear rate six orders of magnitude lower than the steel.
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