Electrodeposition of Ni-B and Ni-Co-B Alloys by Using Boric Acid as Boron Source

Abstract

In this letter, the formation of electrodeposited Ni-B and Ni-Co-B alloys by using boric acid as boron source was demonstrated. The estimated thickness of the films was 5 μm. By means of Cyclic voltammetry, X-ray diffractometry and energy dispersive X-ray spectroscopy analyzes, it was showed that Ni-B and Ni-Co-B alloys, with composition Ni 94 B 6 and Ni 75 Co 21 B 4 , can be easily formed onto glassy carbon when no complexing agents are employed in the electrodeposition bath. These results open the door to the production of electrodeposited boron-containing alloys by using boric acid as precursor due to its low cost and large-scale production. © 2014 The Electrochemical Society. [DOI: 10.1149/2.011405eel] All rights reserved.Manuscript submitted January 29, 2014; revised manuscript received March 5, 2014. Published March 25, 2014 Electro-and electroless plated boron-containing alloys have attracted much attention in the last decades due to their uncommon properties such as high hardness and superior mechanical wear resistance.1,2 Moreover, their application is so vast and includes several fields concerning aerospace, automotive, chemical and electrical industries.3 Among them, binary and ternary alloys such as Ni-B, Co-B, Fe-B, Ni-W-B and Co-Ni-B have been studied with different purposes. [4][5][6] In the case of electroless deposition, the use of strong boron-base reducing agents (borohydride, dimethylamine borane, trimethylamine borane, etc.) is mandatory to obtain boron-containing alloys. Besides the relatively high cost of these compounds, the electroless technique to produce boron alloys is limited to the use at high temperatures (70-90• C) and high pH values (13-14), 7 which in many cases restricts its broad utilization. In view of these facts, the conventional electrodeposition technique appears as an alternative to the boron alloys production. In addition, as reported by Bekish et al., 2 the electrochemical method offers a number of considerable advantages when compared to the electroless one, e.g. operation at room temperature, high deposition rate, electrolyte stability, among others. However, studies concerning electrodeposition of boron-based alloys have only showed their production from baths containing the above-mentioned boron compounds. 4-6Here, we report, for the first time, the electrodeposition of Ni-B and Ni-Co-B alloys from a bath containing boric acid as boron source. By means of cyclic voltammetry, X-ray diffractometry and energy dispersive X-ray spectroscopy analyzes, it was demonstrated that Ni-B and Co-Ni-B alloys can be easily deposited from a simple bath. ExperimentalNi-B and Ni-Co-B Alloys were potentiostatically deposited onto a glassy carbon disk (area = 0.075 cm 2 ). Glassy carbon was chosen as substrate due to its good electrical conductivity and long potential range of electrochemical inactivity. The electrolyte composition used for the alloys electrodeposition was: 0.05 M NiCl 2 , 0.5 M NaCl, and 0.2 M H 3 BO 3 for Ni-B alloy, and the same bath plus 0.025 M CoCl 2 for Ni-Co-B ...