Wear characteristics of nickel electrodeposits in ultrasonically agitated bath
01 Jan 1993-Journal of Materials Science Letters (Kluwer Academic Publishers)-Vol. 12, Iss: 12, pp 902-903
TL;DR: In this paper, the wear rates of nickel electrodeposits obtained from a conventional Watts bath were compared with those obtained with an ultrasonically agitated bath and with a still bath, and wear rates were measured for unlubricated rubbing against a rotating hardened steel disc.
Abstract: Wear rates of nickel electrodeposits obtained from a conventional Watts bath were studied. A comparison was made between the wear rates of nickel electrodeposits obtained with an ultrasonically agitated bath and those obtained with a still bath. Deposition was done on mild steel, and wear rates were measured for unlubricated rubbing against a rotating hardened steel disc. The wear loss of the deposits obtained with the ultrasonic bath was lower than that with the still bath. When ultrasonic waves are passed through the electrolyte solution, bubbles are formed which grow and collapse due to continuous absorption of energy from alternating compression and expansion cycles of the sound waves. This results in work-hardening of the surface, which leads to higher microhardness and higher wear resistance. Nickel plating is widely used for decorative purposes. It also finds application to minimize abrasive wear in cases such as sliding contacts on 2.0 hydraulic rams. The use of ultrasound in a plating bath has been found to improve the surface quality of the deposit. The application of ultrasonic irradiation during plating affects the deposition rate and internal stress [1]. Ultrasound has decreased whisker growth, giving smoother surfaces [2], The fatigue strength of mild steel deposited with nickel is found to be improved when deposition is done in an ultrasonic field [3]. This work was aimed at evaluating the extent to which ultrasonic irradiation influences the wear resistance of the deposit. The composition of the plating bath was 250 g 1-1 nickel sulphate (NiSO4.6H20), 60g1-1 nickel chloride (NiC12.7H20) and 30g l -~ boric acid (H3BO3) in distilled water. Circular specimens, 30 mm in diameter and 5 mm thick, were plated at a current density of 3.5 A dm -2 both in an ultrasonic bath and in a still bath. The ultrasonic generator had a frequency of 22 kHz and a maximum rated capacity of 500 W. The thickness of the deposit was maintained at 40/zm for each specimen. The wear-testing rig used was as described elsewhere [4]. The mating disc was hardened steel of hardness 700 kgmm -2. Both the counter disc and the specimen were of the same diameter and the counter disc rubbed the specimen coaxially. The test Speed duration in all experiments was 30 min. The speci(r.p.m.) mens were weighed before and after the wear test. 700 The wear losses of the deposits were evaluated at 8oo different speeds. The spring load on the specimen 9oo against the counter disc was varied from 7.8 to 1000 11 kgf. 1100 Fig. 1 shows the wear rate of the specimens tested at different sliding speeds. The sliding speed is given by 27rrn/60, where n is the shaft speed in r,p.m. Wear rates were calculated using W = w/dLP, where w is the weight loss of the deposit during testing, d is the density of nickel, L is the sliding distance and P is the normal load. The wear rates of the coatings at different speeds and sliding speeds are listed in Table I. Specimens coated in an ultrasonic field showed a higher wear resistance than nickel coated under still conditions. Fig. 2 shows the wear loss per unit area at different loads, and corresponding data are given in Table II. Optical micrographs were taken after wear testing. Figs 3 and 4 show wear tracks of the specimens plated in a still bath and an ultrasonically
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TL;DR: In this paper, the authors summarized the fundamentals of the use of ultrasound and acoustic cavitation and how it may influence the electrodeposition of composite coatings with particles by commenting on some of the most significant works on this topic presented by the scientific community in the last decade.
Abstract: The electrodeposition of multifunctional composite coatings has rapidly emerged in the last decade due to the enhanced mechanical properties and corrosion resistance that such composite coatings exhibit compared to electroplated single metal and alloy deposits. Many studies have indicated that the implementation of ultrasound in composite electroplating processes can bring about many benefits, not only as a tool to improve the dispersion and de-agglomeration of particles in the electroplating bath, but also to enhance the incorporation of finely dispersed and uniformly distributed particles into the metal matrix. The present paper summarizes the fundamentals of the use of ultrasound and acoustic cavitation and how it may influence the electrodeposition of composite coatings with particles by commenting on some of the most significant works on this topic presented by the scientific community in the last 10 years. This paper will review these investigations and discuss how the ultrasonic parameters may affect the dispersion of the particles in the electrolyte and its effect on the characteristics of the composite coatings, generally resulting in the enhancement of the mechanical properties and corrosion resistance of the composite coatings. In addition, this paper will review some of the issues that may arise when using ultrasound in such processes and the pros and cons of the different transducer systems available, highlighting the need for detailed information regarding the ultrasonic parameters and equipment used when utilising sonication.
96 citations
Cites background from "Wear characteristics of nickel elec..."
...Other mechanical properties can also be improved by using ultrasound during the electrodeposition, Ni coatings being the best example, as sonication during electrodeposition increased the hardness [28], decreased the residual stress [29], and enhanced the wear [30] and fatigue strength [31] of the Ni deposits....
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TL;DR: In this paper, the effect of ultrasonic power on the characteristics of low-frequency ultrasound-assisted electrodeposited Ni coatings from an additive-free Watts bath has been evaluated by different methods.
Abstract: The effect of ultrasonic power on the characteristics of low-frequency ultrasound-assisted electrodeposited Ni coatings from an additive-free Watts bath has been evaluated by different methods. XRD analysis showed that, while mechanical agitation favoured the electrocrystallization of Ni in the [211] direction, ultrasound promoted the electrodeposition of Ni with a [100] preferred orientation. FIB-SEM images of the surface of Ni deposits not only indicated that the surface structure agreed to some extent with the XRD results, but also that ultrasound refined, to a certain extent, some of the grains of the surface of the coatings. FIB-SEM images of the cross-section of the coatings confirmed this effect of ultrasound on the microstructure of the deposits. Such change in the microstructure of Ni, along with work-hardening by ultrasound, resulted in an increase in the hardness of the deposits. The characteristics of the deposits depended on the ultrasonic power employed, and it was found that Ni coatings electrodeposited using an ultrasonic power of 0.124 W/cm3 presented the higher proportion of crystals with a [100] preferred orientation, the highest degree of grain refinement in the surface and the highest microhardness values. Nevertheless, these deposits also presented visible erosion marks on the surface of the coatings due to the formation of transient bubble structures near the surface of the cathode during the electrodeposition. These erosion marks might be considered the main drawback to the use of ultrasound during the electrodeposition.
73 citations
TL;DR: In this paper, the cavitational wear resistance of electroplated nickel composite layers was tested following ASTM G32 Particles of different hardness (titania and silicon carbide) and different sizes from micro-scale to nano-scale were incorporated up to 30 vol% into a nickel matrix.
Abstract: The cavitational wear resistance of electroplated nickel composite layers was tested following ASTM G32 Particles of different hardness (titania and silicon carbide) and different sizes from micro-scale to nano-scale were incorporated up to 30 vol% into a nickel matrix Martens hardness is improved by grain refinement via particle incorporation Compared to pure electroplated nickel films the composite layers strengthened by submicro-scale silicon carbide particles exhibit a decreased mass loss of one order of magnitude after 8 h testing time Remarkably, layers with nano-scaled titania particles show a similar performance Apart from particle adherence failures, reduced mass loss of the composite layers correlate with improved hardness of the composite due to grain refinement of the matrix and dispersion hardening effects
39 citations
TL;DR: In this article, the Ni-W/MWCNTs composite coatings with high MWCNTs content were successfully fabricated by pulse electrodeposition technique using ultrasound agitation.
28 citations
TL;DR: In this article, the correlation between the gained microstructure of the composites with particles from micron to nanometre scale and the electrochemical and mechanical properties was investigated.
Abstract: Electroplated nickel coatings provide ductility, excellent corrosion resistance and good wear resistance, which qualifies them to meet complex demands of engineering, microtechnology and microelectronics. The co-deposition of particles is a promising alternative to deposit layers with adequate microstructure and properties avoiding the rise of residual stress. The incorporation of the sufficient quantity of particles, monodisperse distribution and downsizing to nanometre scale affect the amount of strengthening by dispersion hardening. To avoid agglomeration in the electroplating bath as well as in the layer is a challenge which has been met by simple Watts nickel electrolyte with a minimum of organic additives and adequate bath agitation comprising sonication, i.e. the exposure of the bath to high-frequency sound waves. Well-dispersed hard particles (titanium oxide and silicon carbide) were incorporated in nickel films. The focus was set on the correlation between the gained microstructure of the composites with particles from micron to nanometre scale and the electrochemical and mechanical properties. Corrosion was quantified from polarisation curves and volumetric erosion measurements. Wear resistance was evaluated by scratch energy density studies, oscillating sliding wear testing and cavitation wear testing and compared to indentation hardness results. Sonication and particle downsizing result in matrix grain refinement and dispersion hardening. Incorporation of different particles with respect to different material and size proved to meet different demands. Submicron TiO2 is best for high corrosion resistance, sonicated nickel without particle incorporation is best for high abrasion resistance, nano TiO2 is best for oscillating sliding wear resistance and submicron SiC is best for cavitation wear resistance.
22 citations
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"Wear characteristics of nickel elec..." refers background in this paper
...This behaviour is observed in most metallic systems [5, 6 ]. At lower speeds the contact area between the counter disc and the specimen might be less....
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15 citations
TL;DR: In this article, it was shown that the transition from severe to mild wear and the wear rate of 0.45 wt.% C steel pairs in dry friction were sensitive functions of the normal damping coefficient of the loading system.
10 citations