Improving the corrosion properties of amorphous Ni-P thin films using different additives

Abstract

6Highlights 7  Effects of various additives on the corrosion resistance of Ni-P films is studied. 8 Thinner, more uniform, and smoother Ni-P thin films are formed with additives. 9 Excellent improvement of the corrosion resistance is observed. 11 Abstract 12Ni-P amorphous coatings are considered as important engineering alloys. In this paper, the effects 13 of various additives on the properties of Ni-P thin films were investigated, including saccharine, 14 glycine, pyridinium propyl sulfonate, coumarin, sodium citrate, and cerium sulfate. 15Potentiodynamic polarization and electrochemical impedance spectroscopy tests, scanning 16 electron microscopy, X-ray fluorescence and diffraction, and atomic force microscopy were 17 employed to study the properties of the samples. It was found that a proper concentration of these 18 additives, except saccharine, noticeably improved the corrosion resistance, especially at high 19 potentials (about 25% increase in instantaneous corrosion efficiency and about 300% in corrosion 20 efficiency at high potentials) and decreased the surface roughness (by about 10 to 55 %) of Ni-P 21 thin films. Thinner, more uniform, and less porous coatings were formed in the presence of 22 additives. Except saccharine, all the additives enhanced the P content of Ni-P films, which thus 23 kept their amorphous structure; saccharine highly suppressed the incorporation of P inside the Ni 24 lattice and a mixed amorphous-crystalline structure was stabilized. The preparation of thin film coatings using electrochemical methods is attractive due 3 to their simplicity, the opportunity to work generally at ambient temperature, the 4 uniform and controllable deposition rate, the possibility to form multilayers, the 5 ability to coat large surfaces in almost any shape and geometry, and the low cost thus impede crystalite nucleiation. Therefore, the amount of P in the alloy affects its 35 crystallographic structure; increasing the P content changes the microstructure from 36 3 crystalline to nano-crystalline and finally to an amorphous state. According to the 1 literature, there is not a specific content but a range of P contents for the crystalline 2 to amorphous transition of Ni-P coatings [15]. However, coatings with P contents 3 higher than 8% present usually an amorphous structure [14]. Given that the P content 4 largely determines the properties of Ni-P coatings shows the importance of the 5 chemical composition of the electrodeposition bath. it is well known that 6 introducing even a small amount of certain compounds as additives to the electrolyte 7 significantly affects the properties and appearance of deposits [24]. The refinement 8 of the microstructure, with a decrease of the internal stress and the surface roughness, 9 an increase of the brightness , and the improvement of the corrosion resistance and 10 mechanical properties of the coatings are some of the reported benefits of additives 11 [11,16,17,23,[25][26][27][28][29]. Organic compounds are the most commonly used additives, 12 and they...

Anti-corrosion and microstructural properties of Ni–W alloy coatings: effect of 3,4-Dihydroxybenzaldehyde

“…A thinner coating with more surface coverage ( Ѳ = 0.99) was obtained in the presence of additive (250 ppm) in the bath, which implies a uniform and smoother coating. Even so, the decrease in thickness may be influenced by the additives in the bath through a water side reaction [46]. The current efficiency is found to be higher (51%) in the case of alloy deposits with lower tungsten (39.68 wt%) and for higher tungsten percentage it was of lower current efficiency (45%) (Table 4).…”

Full Optimization of an Electroless Nickel Solution: Boosting the Performance of Low-Phosphorous Coatings

“…According to Figure 1 e, the analysis of the most influential parameters revealed that higher pH, lower stirring rate and higher reducing agent concentration led to coatings characterized by lower corrosion rates. Complexing agents and stabilizers present in ENP baths have been described as corrosion performance modifiers [ 41 , 42 ]. However, the concentration of the complexing agents had little influence on the corrosion performance of the studied NiP coatings according to the S/N ratio values in Figure 1 e.…”

Cu/Ni/Au multilayers by electrochemistry: A crucial system in electronics - A critical review

“…However, coatings with higher Mn contents were found to have a lower corrosion resistance [101]. The incorporation of more Mn occurred in the presence of a higher concentration of glycine that has a negative effect on the corrosion resistance of thin films [155].…”

“…The authors have recently published a paper about improving the corrosion behavior of Ni-P films using organic additives [155]. To summarize, the chemical composition, surface morphology, and crystalline structure of some of the Ni alloy deposits are presented in Table 1.…”