Synthesis of functionally graded nano Al2O3–Ni composite coating by pulse electrodeposition
Graphical abstract
Introduction
Metal matrix composite coatings (MMCs) can show unique physical, mechanical and chemical properties [1], [2], [3]. This makes them promising low cost advanced materials which can be produced by means of electrocodeposition. The advantages of the electrochemical fabrication method compared to other coating methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD) and powder metallurgy include more homogenous distribution of particles, reduced waste materials and ability of continuous processing [4]. However, the dispersion of the particles (particularly for nano particles) in a common plating bath can be problematic. In most cases agglomeration and sedimentation of the particles take place which makes successful co-deposition difficult.
Functionally graded material (FGM) is a novel engineering system developed in the mid-1980s in Japan. In these materials some characteristics like composition and structure gradually change, resulting in material properties changes [5]. It is already known that functionally graded materials may reduce delamination and spallation of coatings [5], [6], [7]. In the simplest FGMs, two different type of structures change gradually from one to the other. The materials can also change in a discontinuous way in a stepwise gradation. So far graded coatings have been produced by various methods such as PVD, CVD, thermal plasma spray and electrodeposition [7]. By using electroplating method, the graded coatings can easily be manufactured by changing the process variables like the current density, rate of stirring and particle loading in the bath. Examples of such graded coatings include a nickel deposit reinforced with SiC microparticles [5], [6], [8], [9] and Al2O3 nanoparticles [7], [10], [11].
Among these parameters the imposed current is one of the most important ones, having a great influence on particle content in the composite coating and consequently on coating properties [3], [4], [12]. Different types of currents like direct current (DC), pulsed current (PC) and pulsed reversed current (PRC) have been employed [4], [12], [13], [14], [15], [16], [17], [18]. PC has been proved to be a useful tool for designing metallic coating properties and a considerable number of theoretical models have been introduced to explain the way pulse current alters the process of electrodeposition [13]. Landolt and Marlot reviewed the effect of PC on microstructure and composition of metallic coatings [13] and recently, many other researchers were employing PC and PRC for production of the composite coatings. Pulsed electrodeposition is employed to produce many different composite coatings like Ni/W–Al2O3 [14], Ni–SiC [15] and Ni–TiO2 [3], [12], and results have shown a possible control of particle content in the coating by using PC [3], [15], [17] or PRC [17] and also enhancement of the uniformity of particle dispersion in the coating. However, the effect of pulse electroplating parameters on incorporation rate and properties of the coating is not always reported the same. For example, in the case of Ni–Al2O3 composite coating, the authors have reported contradictory behaviors by using PC [4], [14], [18].
The main goal of this research is the synthesis of functionally graded nickel–nano Al2O3 composite coatings in which the amount of the embedded nano alumina particles changes in the cross section of the composite. Such composite coatings already were produced by other methods [7], [9], but this is the first time that pulse parameters during electrodeposition process will be used to manufacture functionally graded composite coatings.
Section snippets
Experimental
A modified Watts Ni bath composition and the electroplating process conditions are presented in Table 1. The solutions were prepared from analytic grade chemicals (Merck) and double distilled water. The pH of the bath was adjusted to value (pH = 3.5 ± 0.1) with NH3·H2O (10 wt.%) and H2SO4 (10 wt.%) solutions.
The average particle size of the Alumina powder used in the experiment was about 80 nm. Alumina particles were maintained as suspension in an electrolytic bath by using continuous magnetic
Fabrication of functionally graded coatings by changing the duty cycle
In order to evaluate the effect of duty cycle on fabrication of Ni–Alumina functionally graded nanocomposite coatings, four different coatings were prepared at different frequencies. For each frequency the duty cycle has changed from 90% to 10% to obtain a coating which has less incorporated alumina particles in the first layer. According to the literature [3], [19] the amount of incorporated particles should increase by decreasing duty cycle. Therefore the amount of alumina particles have been
Conclusion
The following conclusions can be drawn from the presented work:
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Functionally graded nano Al2O3–Ni composite coatings can be optimized by changing pulse parameters during electrodeposition process. Among the pulse parameters investigated in this research, the duty cycle showed strongest influence on the fabrication of functionally graded coatings.
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By changing the duty cycle from 90% to 10% at each different frequency, the microstructure of the coatings changes in a same way. These coatings showed
References (24)
- et al.
Characterization of electrodeposited Ni–TiO2 nanocomposite coatings
Surface and Coatings Technology
(2008) - et al.
Ni/nano-TiO2 composite electrodeposits: textural and structural modifications
Electrochimica Acta
(2009) - et al.
Effects of pulse electrodeposition parameters on the properties of Ni–TiO2 nanocomposite coatings
Applied Surface Science
(2010) - et al.
Interface behaviour in nickel composite coatings with nano-particles of oxidic ceramic
Electrochimica Acta
(2003) - et al.
Ni–Co–TiO2 nanocomposite coating prepared by pulse and pulse reversal methods using acetate bath
Applied Surface Science
(2010) - et al.
Microstructure and composition of pulse-plated metals and alloys
Surface and Coatings Technology
(2003) - et al.
Preparation and wear resistance of pulse electrodeposited Ni–W/Al2O3 composite coatings
Applied Surface Science
(2011) - et al.
Effect of pulse electrodeposition parameters on the properties of Ni/nano-SiC composites
Applied Surface Science
(2008) - et al.
Pulse and pulse reverse plating – conceptual, advantages and applications
Electrochimica Acta
(2008) - et al.
The influence of pulse plating parameters on the hardness and wear resistance of nickel–alumina composite coatings
Surface and Coatings Technology
(2005)
Pulsed electrodeposition and characterization of bronze–graphite composite coatings
Surface and Coatings Technology
Hard and corrosion resistant nanocomposite coating for Al alloy
Materials Science and Engineering A
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