NUK - logo
E-viri
Celotno besedilo
Recenzirano
  • Pulsed-DC powder-pack borid...
    Campos-Silva, I.; Hernández-Ramirez, E.J.; Contreras-Hernández, A.; Rosales-Lopez, J.L.; Valdez-Zayas, E.; Mejía-Caballero, I.; Martínez-Trinidad, J.

    Surface & coatings technology, 09/2021, Letnik: 421
    Journal Article

    An alternative method called pulsed-DC powder-pack boriding process (PDCPB) is presented in this study. The main components of the PDCPB consisted of a metal box containing the specimen embedded in a powder mixture, and placed between two electrodes, which were connected to a DC power supply, and a programmable electronic control device producing the polarity changes during the process. A set of boriding conditions were carried out on the surfaces of AISI 316 L stainless steel and Inconel 718 superalloy using a constant current input of 5 A with polarity inversion cycles of 10 s. After the PDCPB, the boride layers were characterized by optical microscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The growth kinetics of the boride layers was established using a diffusion model that considered the mass balance equations at the growth interfaces, in which the boron diffusion coefficients in the layers were expressed as a function of the boriding temperatures to estimate the boron activation energies in the borided materials. The change of polarity in the electrodes allowed a uniform flux of boron during the process, obtaining similar layer thicknesses on the surfaces of the material exposed to the pulsed-DC field. Finally, the results showed that the growth rate of the layers was increased by the effect of the pulsed-DC field, whilst the boron activation energies, in the borided materials, decreased drastically compared to those obtained for the conventional powder-pack boriding process. •A novel method denominated pulsed-DC powder-pack boriding is presented in this work.•Uniform boron fluxes were produced on the surfaces exposed to pulsed-DC field.•Pulsed-DC field developed similar layer thicknesses at the material surface.•Pulsed-DC field increased the growth kinetics of boride layer in treated materials.