Impact of waveform shape on the properties of Ni coatings in pulsed electro-deposition for durability of industrial surfaces: A comparative study of rectangular and triangular pulses

Electrodeposition is one of the effective and low-cost processes in surface coating technology. It offers electrodeposits with dense structure and good mechanical and anti-corrosive properties. In recent years, pulsed current deposition has emerged as a prominent high-tech manufacturing method for various micro-devices, electronic boards, optical disks, micro-transducers, and corrosion-resistant coatings. However, predominant research efforts have focused on using rectangular pulse currents to optimize the deposit's quality. Other waveform options have received comparatively less attention. So, this study investigated the pulsed current deposition of Ni coatings on mild steel substrate using two distinct waveforms, such as rectangular and triangular pulses, at 50 % relaxation time, 10Hz frequency and explored their impact on properties of Ni electrodeposits in Nickel sulphamate bath at pH of 4.12. Comparative analysis of deposits revealed consistent results at the same deposition conditions. From X-ray diffraction, the orientation densities of (111) and (101) textures and the average grain size of 75 nm at (111) for both rectangular and triangular pulsed current deposits. In contrast, Direct current yielded larger grain sizes of 110 nm. Moreover, the triangular waveform facilitated instantaneous peak currents for charge transfer, resulting in finer grain sizes, and reduced pore structures led to improve the surface hardness, corrosion resistant and wear resistant properties by 40 %, 80 % and 40 % respectively compared to DC, and when compared to rectangular pulse current tha same properties enhanced by 30 %, 60 % and 30 % respectively, Therefore, waveform shape significantly influenced electrodeposit behaviour under equivalent average and peak current densities.