In this work Ni coatings with different boron content (0.6 to approximately 3.4 wt.%) wereproduced by electrodeposition from a sulfamate bath containing dimethylamineborane (DMAB). Theinfluence of boron concentration on the structure, morphology, crystal size and hardness of thecoatings was investigated using plasma emission spectroscopy (ICP), scanning electron microscopy(SEM) and X-ray diffractometry (XRD). Crystal size and structure were evaluated in both as-platedand thermal-treatment conditions to establish their relationship to the hardness of the coating. Thecorrosion resistance of the coatings was evaluated in 5% NaCl, employing electrochemical polarizationmeasurement and salt spray testing. The results showed that the increased hardness of the as-plated Ni- B coatings is primarily caused by a reduction in crystal size rather than boron composition. Thus, Ni-Bcoatings can be produced with high hardness (716 22.5 HV) with a relatively low boron composition(1.8 wt. %). On the other hand, Ni-B coatings produced after thermal treatment showed that hardnessdepends on two factors: composition (Ni3B) and crystal size, achieving the highest hardness at 350C(1105 19.4 HV). Unless the obtained Ni-B coatings showed a high hardness, the corrosion resistanceis low due to the presence of cracks.
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