TY - JOUR
T1 - Pulsed-DC powder-pack boriding
T2 - Growth kinetics of boride layers on an AISI 316 L stainless steel and Inconel 718 superalloy
AU - Campos-Silva, I.
AU - Hernández-Ramirez, E. J.
AU - Contreras-Hernández, A.
AU - Rosales-Lopez, J. L.
AU - Valdez-Zayas, E.
AU - Mejía-Caballero, I.
AU - Martínez-Trinidad, J.
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/9/15
Y1 - 2021/9/15
N2 - 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.
AB - 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.
KW - Activation energies
KW - Boride layers
KW - Electromigration
KW - Growth kinetics
KW - Pulsed-DC powder-pack boriding
UR - http://www.scopus.com/inward/record.url?scp=85109036980&partnerID=8YFLogxK
U2 - 10.1016/j.surfcoat.2021.127404
DO - 10.1016/j.surfcoat.2021.127404
M3 - Artículo
AN - SCOPUS:85109036980
SN - 0257-8972
VL - 421
JO - Surface and Coatings Technology
JF - Surface and Coatings Technology
M1 - 127404
ER -