Electrodeposition and Characterization of Ni/Al2O3 Nanocomposite Coatings

Abstract

The composite coatings containing of nanocrystalline Ni matrix and hard nano-sized γ-Al 2 O 3 were electrodeposited in a system with a rotating disk electrode. The bath composition (nickel salts and buffer concentration, presence of surface-active agents and inert particles) influence on kinetics of Ni electrodeposition as well as on structural properties (morphology, phase composition, texture, residual stresses) and microhardness of Ni/Al 2 O 3 coatings has been investigated. SEM and TEM studies show more uniform arrangement of Al 2 O 3 particles in the matrix, however a tendency to agglomeration is observed. Surfactant application to a saccharine containing bath effectively improves the dispersion of nanoparticles into the nickel matrix. The addition of Al 2 O 3 particles results in decrease of the average Ni crystallite size. The introduction of additive into electrolyte solution resulted in change of stress character of composite coatings (from tensile to compressive). The microhardness of Ni matrix was enhanced (about 40%) due to incorporation of ceramic particles.Keywords: electrodeposition, nanocomposite, nickel coatings, Al 2 O 3 nanoparticles Nanokrystaliczne powłoki kompozytowe z osnową Ni zawierające ceramiczną fazę dyspersyjną w postaci γ-Al 2 O 3 o rozmiarach nanometrycznych zostały elektroosadzone w układzie z wirującą elektrodą dyskową. W pracy analizowano wpływ składu kąpieli (zawartość soli niklu, obecność związków powierzchniowo-czynnych i cząstek obojętnych) na kinetykę procesu elektroosadzania, jak również na właściwości strukturalne (morfologię, skład fazowy, teksturę, naprężenia własne) oraz mikrotwardość powłok Ni/Al 2 O 3 . Badania wykonane za pomocą SEM i TEM wykazały, że cząstki Al 2 O 3 są w znacznym stopniu równomiernie rozmieszczone w osnowie, jednak z tendencją do aglomeracji. Dodanie środka powierzchnio-czynnego do kąpieli zawierającej sacharynę zwiększyło dyspersję nanocząstek w osnowie niklu. Stwierdzono, że obecność cząstek Al 2 O 3 powoduje obniżenie wielkości krystalitów osnowy Ni. Wprowadzenie dodatków do elektrolitu wpłynęło na zmianę charakteru naprężeń własnych uzyskanych powłok, jak również na ich mikrotwardość (wzrost o około 40%).

Taguchi Design of Internal Stress and Friction Measurements during Electrodeposition

“…The result is consistent with the claim of Chou et al [7] that is particle incorporation in nickel deposits has decreasing effect on internal stress. Moreover, thickness effect result also agrees with the study [8]. The interaction parameters were given in Figure 5.…”

Ni–W/ZrO2 nanocomposites obtained by ultrasonic DC electrodeposition

“…It is well known that the dispersion of ceramic nanoparticles in a plating bath is a very important stage of the electrodeposition process that strongly influences the nanocomposite properties [21,23]. To suppress or prevent agglomeration, prior to plating process the zirconia nanoparticles were mechanically dispersed in the bath using a stirrer (500 rpm) for 24 h. During the last 5 h, the suspension was additionally treated by ultrasounds.…”

“…Thus, it would be expected that the incorporation of zirconium oxide as ceramic hard particles into Ni-W alloy matrix allows composites of outstanding characteristics to be obtained, taking into account the properties of both components and their nanocrystalline microstructure. Moreover, the results of our previous study on electrodeposition and characterization of Ni/Al 2 O 3 and Ni-W/Al 2 O 3 composites showed a significant improvement of the microhardness and wear resistance as compared to the pure nickel coatings [14,23,24].…”

The influence of pulse plating parameters on microstructure and properties of Ni-W-Si3N4 nanocomposite coatings

“…Before deposition, in order to suppress agglomeration, Si 3 N 4 nanoparticles were dispersed in the plating bath ultrasonically for 30 min and then by mechanical stirring for further 2 h. Besides, the sodium dodecyl sulfonate (SDS) used together with cetyltrimethyl ammonium bromide (CTAB) as dispersant to further maintain the homogeneous dispersion and the stability of Si 3 N 4 while stirring [23]. According to Sangeetha and Kalaignan [24], by adding dispersant, zeta potential of the nanoparticles would be increased.…”