Abstract
Molten salt electrolysis was applied for the boronizing of nickel with Na2B4O7·10H2O-Na2CO3 as the electrolyte and characterizations and the growth kinetics of borided layer is reported. The experiment was carried out in silicon carbide crucible at 1193 K, 1223 K, and 1243 K for 1 h, 2 h, 3 h, and 4 h. The morphology and phases formed on the surface of pure nickel were analyzed by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis (XRD). The surface hardness and corrosion resistance of the boronized sample were tested by micro hardness tester and electrochemical workstation, respectively. The borided layer was composed of nickel borides and its thickness ranged from 71 to 184 μm. After 1 h of boronizing, the hardness of the silicon rich borides is 966 HK, which is a little lower than that of the nickel borides (992-1008 HK); the surface hardness reached 1755 HK after 4 h electrolysis. Electrochemical impedance spectroscopy analysis showed that the corrosion resistance of boronized sample is better than that of pure nickel. Borided layer growth kinetics was studied by analyzing the relationship between thickness of the borided layer and time by mathematical method. Then the diffusion coefficient constant of boron atom in nickel at 1193 K, 1223 K and 1243 K was calculated accordingly and an equation was obtained to estimate the thickness of the borided layer.
Keywords
References
Authors retain copyright of the published papers and grant to the publisher the non-exclusive right to publish the article, to be cited as its original publisher in case of reuse, and to distribute it in all forms and media.
The Author(s) warrant that their manuscript is their original work that has not been published before; that it is not under consideration for publication elsewhere; and that its publication has been approved by all co-authors, if any, as well as tacitly or explicitly by the responsible authorities at the institution where the work was carried out. The Author(s) affirm that the article contains no unfounded or unlawful statements and does not violate the rights of others. The author(s) also affirm that they hold no conflict of interest that may affect the integrity of the Manuscript and the validity of the findings presented in it. The Corresponding author, as the signing author, warrants that he/she has full power to make this grant on behalf of the Author(s). Any software contained in the Supplemental Materials is free from viruses, contaminants or worms.The published articles will be distributed under the Creative Commons Attribution ShareAlike 4.0 International license (CC BY-SA).
Authors are permitted to deposit publisher's version (PDF) of their work in an institutional repository, subject-based repository, author's personal website (including social networking sites, such as ResearchGate, Academia.edu, etc.), and/or departmental website at any time after publication.
Upon receiving the proofs, the Author(s) agree to promptly check the proofs carefully, correct any typographical errors, and authorize the publication of the corrected proofs.
The Corresponding author agrees to inform his/her co-authors, of any of the above terms.