Cavitation erosion of electroplated nickel composite coatings

Ultrasound-assisted electrodeposition of nickel: Effect of ultrasonic power on the characteristics of thin coatings

“…On the other hand, the increase in hardness of the coatings deposited under ultrasound is concurrent with previous studies by Prasad et al [16] (from 235 HV to 332 HV in 50-micron-thick Ni coatings deposited on mild steel cathodes in a Watts bath at 4 A/dm 2 in a 22 kHz ultrasonic bath), Zanella et al [56] (from ≈ 300 HV to ≈ 320 HV in Ni coatings plated onto a low carbon steel substrate in a Watts bath at 2 A/dm 2 under undefined ultrasonic conditions), and García-Lecina et al [57] (from ≈ 250 HV to ≈ 300 HV in Ni coatings plated onto mild steel cathodes in a Watts bath at 5 A/dm 2 with a 24 kHz ultrasonic horn). In this latter case, the authors pointed out that the increase in hardness would be due to a change in the structure of the deposit, as previously suggested by Lampke et al [58]. The higher presence of smaller grains on the surface of Ni coatings electrodeposited under ultrasound at 0.124 W/cm 3 and 0.180 W/cm 3 and the grain size refinement and fragmentation of the microstructure observed in those same deposits would therefore be responsible to some extent for the increase in hardness observed in the thin Ni coatings electrodeposited under ultrasound at higher power.…”

“…Grain refinement and structure modification by ultrasound have already been widely suggested in the past [54,55], although most of the works available in the literature related to electrodeposited Ni coatings only show either some evidence of the grain refinement effect by ultrasound on the surface of the coatings [20,56,57] or did not show any real evidence at all [19]. Regarding this, Lampke et al's backscattered electron beam diffraction (EBSD) results showed that, whereas large Ni crystals were still noticeable in Ni deposits produced under ultrasound, many small crystals could be observed, resulting in an overall grain refinement when compared with Ni coatings electrodeposited in the absence of ultrasound [58]. A very similar effect in the grain structure was observed in the present study, as the use of ultrasound during the electrodeposition, particularly at high powers, resulted in a more fragmented structure where columnar crystals were observed alternating with very small grains.…”

Ultrasonic Cavitation at Solid Surfaces

“…These alloys have signifi cant potential in fl uid pumps since their good cavitation erosion resistance complements their excellent mechanical properties, corrosion properties and low density. The resistance of nickel dispersion layers under cavitational load was described in the work of Lampke et al [ 70 ] Fatigue cracks frequently develop In pure nickel fi lms and propagate along boundaries of columnar nickel grains during cavitational stress. Discrete regions near the surface are ejected mainly by ductile fracture failures.…”

Ultrasonic Electrodeposition of Cu–SiC Electrodes for EDM

“…The use of ultrasound not only promotes the incorporation of uniformly distributed particles into the matrix metal but also increases the amount of particles integrated into the plated composite material [13,14]. Lampke et al observed that the application of ultrasound yielded a far more homogeneous coating with no large aggregates [15]. A more uniform distribution of particles in the deposits was also observed by Dietrich et al [16].…”