Effect of current waveform on the deposit quality of electroformed nickels

Corrosion Behavior of Coarse- and Fine-Grain Ni Coatings Incorporating NaH2PO4.H2O Inhibitor Treated Substrates

“…Some studies report an improvement in corrosion resistance 6,11,12 while others show behavior comparable to polycrystalline Ni 10 . It has also been reported that nanocrystalline Ni exhibited active-passive-transpassive polarization characteristics similar to coarse-grained polycrystalline Ni [5][6] . In the present study, carbon steel samples were treated with sodium dihydrogen orthophosphate NaH2PO4.H2O inhibitor prior to Ni electrodeposition.…”

“…Also, the corrosion rate (CR) observed for fine grained Ni was lower than its coarse grained counterpart (Table 1). This is attributed to more compact microstructure of fine grained Ni electrodeposit that results in an increase in the resistance to anodic dissolution 5,12 . The electrochemical behavior of inhibitor treated electrodeposits followed a pattern similar to that of untreated electrodeposits.…”

“…Electrolytic method of deposition is selected when it is required to have some control over the crystallite size, surface morphology and orientation of Ni which in turn significantly affects surface related properties of the coatings. Conventionally, Ni coatings have been prepared using dc electrochemical methods [4][5][6][7] . More recently, use of pulse electrodeposition has become popular since it results in Ni coatings with refined grain structure 8,9 and attractive corrosion [10][11][12] and tribological properties [13][14][15][16][17][18] .…”

Corrosion tests of nickel coatings prepared from a Watts-type bath

“…Ni electrodeposition is usually performed at high temperatures (50-70°C) and at high current densities. [17][18][19][20] Electrodeposition of Ni has been reported both through direct current [21][22][23][24][25] and pulse 26 methods. The literature reveals that in direct current electrodeposition, an increase in current density leads to a corresponding decrease of the grain size of the deposits, this behavior being attributed to the evolution of more hydrogen at the cathode interface at higher current densities.…”

“…The presence of the hydrogen modifies the growth interface on the cathode by influencing the surface energy and growth mechanisms, which in the end will facilitate the formation of larger grains in the deposited layer. 23,27 Corrosion resistance can be affected by the microstructure, such as grain size, surface morphology, and texture, which are closely related to the electrodeposition parameters. Electrodeposited nickel generally shows a better corrosion resistance as a grain's crystal size decreases, 18 but there are also other contradictory results reported in the literature.…”