Electroless cobalt coating of BNi-2 powders: process development and characterization
Original scientific paper
DOI:
https://doi.org/10.5599/jese.3245Keywords:
Ni-based braze alloy, brazing powder modification, cobalt plating, plating experimental design, coated powderAbstract
Electroless cobalt deposition and examination of how cobalt enrichment on the particle surface modifies the chemical composition and thermal behaviour of the commercial
BNi-2 brazing alloy powder was investigated in this study. A multi-step surface preparation sequence involving oxide removal, Sn-based sensitization, and Pd activation was employed prior to cobalt deposition in an alkaline CoSO₄-NaH₂PO₂ bath. A design of experiments approach was used to evaluate the influence of plating temperature, cobalt sulphate concentration, hypophosphite concentration, and coating time on cobalt uptake. ICP-OES analyses showed that cobalt incorporation increased from 1.1 to 7.0 wt.% across the selected parameter range. Differential scanning calorimetry revealed that coating levels up to 7 wt.% Co elevate the solidus temperature, while decreasing the liquidus temperature, resulting in a narrower melting interval. Thermodynamic simulations confirmed these trends, showing suppression of borides and enhanced γ/γ′ stability where γ denotes the Ni-rich face-cantered cubic matrix phase and γ′ represents the ordered Ni₃(Al,Ti)-type strengthening phase with increasing cobalt content. EDS mapping of coated powder showed continuous cobalt distribution at the particle perimeter. Overall, the results provided a quantitative basis for linking coating parameters to cobalt incorporation and corresponding modifications in melting behaviour.
Downloads
References
[1] M. Baranowski, J. Senkara, Brazing of selected heat-resisting alloys using Ni-Pd filler metal, Welding Technology Review 91 (2019) 51-58. https://doi.org/10.26628/wtr.v91i10.1078 DOI: https://doi.org/10.26628/wtr.v91i10.1078
[2] K. Krystek, I. Dul, M. Wierzbińska, M. Motyka, Effect of vacuum brazing conditions of Inconel 718 superalloy sheets on microstructure and mechanical properties of joints, Archives of Metallurgy and Materials 69 (2024) 761-773. https://doi.org/10.24425/amm.2024.149808 DOI: https://doi.org/10.24425/amm.2024.149808
[3] M. A. Penyaz, A. A. Ivannikov, O. N. Sevryukov, B. A. Kalin, Overview of nickel-based filler metals for brazing of austenitic stainless steels, Non-Ferrous Metals 50 (2021) 41-56. https://doi.org/10.17580/nfm.2021.01.06 DOI: https://doi.org/10.17580/nfm.2021.01.06
[4] M. A. Arafin, M. Medraj, D. P. Turner, P. Bocher, Transient liquid phase bonding of Inconel 718 and Inconel 625 with BNi-2: Modelling and experimental investigations, Materials Science and Engineering A 447 (2007) 125-133. https://doi.org/10.1016/j.msea.2006.10.045 DOI: https://doi.org/10.1016/j.msea.2006.10.045
[5] A. Khorram, O. Fakhraei, M. J. Torkamany, Laser brazing of Inconel 718 and Inconel 600 with BNi-2 nickel-based filler metal, The International Journal of Advanced Manufacturing Technology 88 (2017) 2075-2084. https://doi.org/10.1007/s00170-016-8897-5 DOI: https://doi.org/10.1007/s00170-016-8897-5
[6] C. Xia, M. Zhao, W. Sun, P. Liu, H. X. Li, Microstructure and properties of 3D printed Inconel 718 joint brazed with BNi-2 amorphous filler metal, Materials Research 22 (2018) e20180348. https://doi.org/10.1590/1980-5373-MR-2018-0348 DOI: https://doi.org/10.1590/1980-5373-mr-2018-0348
[7] B. Binesh, M. Aghaie-Khafri, A. Fayegh, Processing of IN718/Ti-6Al-4V bimetallic joint using transient liquid phase bonding: Effect of bonding temperature on the microstructure and mechanical properties, Philosophical Magazine 102 (2022) 745-771. https://doi.org/10.1080/14786435.2021.2012612 DOI: https://doi.org/10.1080/14786435.2021.2012612
[8] S. P. Kaleybar, H. Khorsand, Effect of bonding temperature on microstructure and mechanical properties of TLP-bonded Ti-6Al-4V/Inconel 718 joints using BNi2/Cu interlayer, Journal of Advanced Joining Processes 12 (2025) 100328. https://doi.org/10.1016/j.jajp.2025.100328 DOI: https://doi.org/10.1016/j.jajp.2025.100328
[9] G. Yan, A. Bhowmik, B. Nagarajan, X. Song, S. C. Tan, M. J. Tan, Bonding temperature effects on the wide gap transient liquid phase bonding of Inconel 718 using BNi-2 paste filler metal, Applied Surface Science 484 (2019) 1223-1233. https://doi.org/10.1016/j.apsusc.2019.04.070 DOI: https://doi.org/10.1016/j.apsusc.2019.04.070
[10] A. Ivannikov, B. Kalin, O. Sevryukov, M. Penyaz, I. V. Fedotov, V. Misnikov, M. Tarasova, Study of the Ni-Si-Be system as a base to create boron-free brazing filler metals, Science and Technology of Welding and Joining 23 (2017) 187-197. https://doi.org/10.1080/13621718.2017.1361668 DOI: https://doi.org/10.1080/13621718.2017.1361668
[11] N. Siredey-Schwalller, J. Hamel-Akré, L. Peltier, A. Hazotte, P. Bocher, Solidificaton sequence of Ni-Si-Cr 3 wt% B brazing alloys, Welding in the World 61 (2017) 1253-1265. https://doi.org/10.1007/s40194-017-0503-4 DOI: https://doi.org/10.1007/s40194-017-0503-4
[12] S. K. Tung, L. C. Lim, M. O. Lai, Solidification phenomena in nickel base brazes containing boron and silicon, Scripta Materialia 34 (1996) 729-734. https://doi.org/10.1016/1359-6462(95)00577-3 DOI: https://doi.org/10.1016/1359-6462(95)00577-3
[13] L. Hardwick, P. Rodgers, E. Pickering, R. Goodall, Development of a Novel Ni-Based Multi-principal Element Alloy Filler Metal, Using an Alternative Melting Point Depressant. Metallurgical and Materials Transactions A 52 (2021) 2534-2548, https://doi.org/10.1007/s11661-021-06246-0 DOI: https://doi.org/10.1007/s11661-021-06246-0
[14] K. Bobzin, H. Heinemann, M. Erck, Microstructural modification by redesigning the chemical composition of Ni 620 filler metal, Advanced Engineering Materials 25 (2023) 2300318. https://doi.org/10.1002/adem.202300318 DOI: https://doi.org/10.1002/adem.202300318
[15] M. Pouranvari, A. Ekrami, A. H. Kokabi. Role of base-metal composition in isothermal solidification during diffusion brazing of nickel-based superalloys, Science and Technology of Welding and Joining 23 (2018) 13-18. https://doi.org/10.1080/13621718.2017.1321335 DOI: https://doi.org/10.1080/13621718.2017.1327934
[16] X. Yang, L. Xu, Y. Gao, Y. Liang, X. Zhang, Y. Yang, Performance of the GH4169 joint using a novel Ni-based brazing filler metal designed via phase diagram calculations, Metals 14 (2024) 1274. https://doi.org/10.3390/met14111274 DOI: https://doi.org/10.3390/met14111274
[17] J. S. C. Jang, H. P. Shih, Study of the nano-structured nickel-based brazing filler synthesized by mechanical alloying, Materials Chemistry and Physics 70 (2001) 217-222. https://doi.org/10.1016/S0254-0584(00)00507-1 . DOI: https://doi.org/10.1016/S0254-0584(00)00507-1
[18] J. Huang, Z. Chen, Method for electroless nickel plating on the surface of CaCO₃ powders, RSC Advances 7 (2017) 25622-25629. https://doi.org/10.1039/C7RA03110F DOI: https://doi.org/10.1039/C7RA03110F
[19] A. Kilicarslan, F. Toptan, H. Koralay, Electroless nickel-phosphorus coating on boron carbide particles, Journal of Materials Engineering and Performance 21 (2012) 966-973. https://doi.org/10.1007/s11665-011-0021-0 DOI: https://doi.org/10.1016/j.matlet.2012.02.037
[20] J. Sudagar, J. Lian, W. Sha, Electroless nickel, alloy, composite and nano coatings - A critical review, Journal of Alloys and Compounds 571 (2013) 183-204. https://doi.org/10.1016/j.jallcom.2013.03.107 DOI: https://doi.org/10.1016/j.jallcom.2013.03.107
[21] E. Hosseini, M. Amirjan, N. Parvin, Preparation and characterization of nickel-based brazing powder: Cobalt and chromium addition effects, Powder Metallurgy 66 (2023) 64-76. https://doi.org/10.1080/00325899.2022.2073013 DOI: https://doi.org/10.1080/00325899.2022.2073013
[22] T. Göynük, Z. Esen, İ. Karakaya, Enhancement of brazing performance of Inconel 718 by electroless cobalt coated nickel-based brazing alloys, Journal of Materials Research and Technology 39 (2025) 4705-4713. https://doi.org/10.1016/j.jmrt.2025.10.110 DOI: https://doi.org/10.1016/j.jmrt.2025.10.110
[23] T. Göynük, İ. Karakaya, G. Can, M. Yücel, Patent application filed Production of composite nickel-based vacuum hard soldering alloy powder by electroless plating, Roketsan Roket Sanayi ve Ticaret A.Ş., TR2025/013192, 2025. https://portal.turkpatent.gov.tr/anonim/arastirma/patent/sonuc/dosya?patentAppNo=2025/013192&documentsTpye=all (in Turkish)
[24] L. Guo, X. J. Zhao, L. R. Xiao, C. R. Tang, W. Y. Zhang, X. X. Tu, X. Z. Liu, Y. C. Nie, Kinetic study of electroless cobalt deposition on WC particles, Journal of Alloys and Compounds 750 (2018) 774-780. https://doi.org/10.1016/j.jallcom.2018.04.064 DOI: https://doi.org/10.1016/j.jallcom.2018.04.064
[25] Minitab LLC, Minitab® Statistical Software, Pennsylvania, USA, https://www.minitab.com/en-us/.
[26] Sente Software Ltd., JMatPro® Software, Surrey, United Kingdom, https://www.sentesoftware.co.uk.
[27] M.-A. Chen, N. Cheng, Y.-C. Ou, J.-M. Li, Corrosion performance of electroless Ni-P on polymer coating of MAO coated AZ31 magnesium alloy, Surface and Coatings Technology 232 (2013) 726-733. https://doi.org/10.1016/j.surfcoat.2013.06.087 DOI: https://doi.org/10.1016/j.surfcoat.2013.06.087
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Tansu Göynük, İshak Karakaya
This work is licensed under a Creative Commons Attribution 4.0 International License.
