**1. Introduction**

Metal matrix composite (MMC) coatings are promising materials developed by inclusion of a dispersed reinforcing material into a metal matrix. MMC's can replace traditional materials through their ability to offer improved mechanical and physical properties such as increased hardness, wear resistance, low thermal expansion coefficients, lubrication properties, antibacterial properties and improved corrosion resistance [1–11]. Nanosized particle incorporation

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

in metal matrixes forms a nanocrystalline structure, leading to improved properties of the material due to modification of the growth of the deposit [7, 12]. The properties of the composite coating are dependent on concentration, size, distribution and type of nanoparticle incorporated, in addition to the method and parameters used during coating formation [13, 14]. Although there are a large number of successful metal/particle combinations, this review will focus on zinc-nickel nanoparticle coatings exclusively. Individually nickel has been successfully co-deposited with a number of materials including TiO2 , SiC, Al2 O3 , PTFE and layered silicates such as montmorillonite (Mt) [2, 7, 15–19] and zinc has been successfully co-deposited with TiO2 , CeO2 , ZrO2 , SiO2 , mica particles and polymeric nano-aggregates (PNAs) [20–25] but a review of current literature on ZnNi alloy nanocomposite coatings has not been compiled to our knowledge. An overview of the literature is shown in **Table 1**. The most commonly used reinforcement material for zinc-nickel coatings is Al2 O3 constituting ~32% of the papers, followed by TiO2 and SiO2 /SiC with ~20% each, carbon nanotubes and CeO2 with ~8% each, and Al2 O3 /SiC, CeO2 /SiO2 and Mt with ~4% each [11–13, 26–48].

**Reference and application**

[36, 37]

Shourgeshty et al.

250 g/L ZnCl2

NiCl2 . 6H2

NiCl2 . 6H2

NaCH3

NiSO4 . 6H2

56.8 Na2 SO4 , 0.53 H2 SO4 ,

pH = 2.5

NiSO4 . 6H2

0.15 M H3

60 ZnCl2

NaCH3

NiSO4 . 6H2

Na2 SO4 . 10H2

40 g/L Na2

120 KCl, 100 NH4

160 g/L ZnSo4

57.5 g/L ZnSO4

131 g/L NiSO4

100 g/L ZnSO4

100 g/L NiSO4

125 g/L ZnSO4

COO. 3H2

> . 7H2

NaCH3

NiSO4 . 6H2

NiSO4 . 6H2

pH = 4

Takahashi et al. [46] 1 M ZnSO4

100 g/L NH4

57.5 g/L ZnSO4

Zheng et al. [38, 39] 60 g/L ZnCl2

Gomes et al. [40, 41] 0.10 M ZnSO4

, 150 g/L

BO3 ,

Cl,

O, 45 g/L H3

, 120 g/L

O, 120 g/L KCl,

Cl, 30 g/L

COO, pH = 5.0

. 7H2

. 7H2

, 120 g/L NiCl2

COO, pH = 4.6

. 7H2

SO4

trimethyl ammounium bromide, pH = 4

O, 12 g/L H3

. 7H2 O,

. 6H2 O, 162

. 7H2 O,

. 6H2

citric acid, 0.5 g/L thiamine hydrochloride, pH = 3.0 ± 0.05

O, pH = 2.0

. 7H2

O, 25 g/L H3

BO3 , pH = 4

O, 9.3 g/L H3

O, 52.5 g/L

BO3 ,

O, 0.30 M

. 6H2 O,

O, 16 g/L

, 1.5 g/L cetyl

O, pH = 2.0–2.5

O, 75 g/L

O, 2 g/L

O, 0–0.7 M

O, 75 g/L

BO3 ,

BO3 ,

Cl, 30

,

O, 0.20 M MgSO4

100 g/L KCl, 100 g/L NH4

0.5 g/L, pH = 4 ± 0.5

Corrosion, wear properties

Momeni et al. [14] Hardness, antibacterial properties

Katamipour et al.

Praveen et al. [43] Corrosion

Tuaweri et al. [30, 44]

Corrosion

Ullal et al. [45] Corrosion

Poliak et al. [47] Mechanical properties

[42] Corrosion, mechanical **Plating bath Incorporated particle and** 

α-Al2 O3 ~20 ± 5 nm 15 g/L 4 A/dm2

α-Al2 O3

50 g/L 4 A/dm2

TiO2 0.0–3.0 g/L 1 A/dm2

TiO2

TiO2

3 g/L 3.5 A/dm2

TiO2

3 g/L 2 A/dm2

SiO2 13–52 g/L 1–10 A/dm2

SiO2

5 g/L

SiO2

SiO2

1 g/L 2A/dm2

specified

0–300 g/L 100 A/dm2

, ~25 nm

10 g/L −3.2 A/dm2

**deposition parameters**

, 30 ± 2°C

, 35 ± 1°C

, 35°C

, particle size ~25 nm

, 35 ± 1°C

, ~100–200 nm

, 27°C

nanopowder

Deposition current and temp—not

colloid (Cataloid SN)

, 50°C

powder, ~10 nm

, Room Temp

, particle diameter ~100 nm

**Dispersion method**

189

Electrodeposited Zinc-Nickel Nanocomposite Coatings http://dx.doi.org/10.5772/intechopen.80219

> Magnetic stirring 12 h prior to deposition, 300 rpm, followed by 1 h ultrasonication (250 W, 20 KHz). During deposition mechanical stirring, 150 rpm and ultrasonic waves (50 W,

20 KHz).

Magnetic stirring 24 h, 2000 rpm prior to deposition. Ultrasound generator and mechanical stirring (200 rpm) during deposition.

Stirring during deposition, 500 rpm.

Ultrasonic agitation 30 min prior to deposition. Stirring during deposition, 400 rpm.

Magnetic stirring, 1500 rpm 24 h prior to deposition. Ultrasound generator and stirring during deposition, 600 rpm.

Magnetic stirring 10 h prior to deposition.

Agitation through use of vibro-agitation with vibromixer prior to deposition.

Magnetic stirring 24 h prior to deposition. Agitation of solution with circulation pump during deposition.

Not specified

Not specified

Zinc-nickel coatings are well known in the field of corrosion resistance as a corrosion resistant material. Corrosion protective coatings are commonly used to extend the lifetime of materials such as stainless steel from corrosion onset as a substitute for more expensive, less available materials [49–53]. Coating zinc onto stainless steel, known as galvanization, is an industry standard to protect against corrosion. The zinc coating sacrificially corrodes, thereby protecting the stainless steel from corrosion [54–56]. Options are now being explored to withstand harsher conditions, longer lifetimes, reduced thickness and better overall strength of the protective coating layer. Although a large focus has been on the development of generalized corrosion resistant coatings, when considering cost, environmental impact and performance,



**Reference and application**

CeO2

fully co-deposited with TiO2

188 Nanocomposites - Recent Evolutions

~32% of the papers, followed by TiO2

with ~8% each, and Al2

Blejan et al. [17] Corrosion

Ghaziof et al. [33, 34]

Corrosion, microhardness

Ataie et al. [35] Tribological properties

**Plating bath Incorporated particle and** 

Al2 O3

in metal matrixes forms a nanocrystalline structure, leading to improved properties of the material due to modification of the growth of the deposit [7, 12]. The properties of the composite coating are dependent on concentration, size, distribution and type of nanoparticle incorporated, in addition to the method and parameters used during coating formation [13, 14]. Although there are a large number of successful metal/particle combinations, this review will focus on zinc-nickel nanoparticle coatings exclusively. Individually nickel has

and layered silicates such as montmorillonite (Mt) [2, 7, 15–19] and zinc has been success-

(PNAs) [20–25] but a review of current literature on ZnNi alloy nanocomposite coatings has not been compiled to our knowledge. An overview of the literature is shown in **Table 1**. The

, SiO2

and SiO2

/SiO2

Zinc-nickel coatings are well known in the field of corrosion resistance as a corrosion resistant material. Corrosion protective coatings are commonly used to extend the lifetime of materials such as stainless steel from corrosion onset as a substitute for more expensive, less available materials [49–53]. Coating zinc onto stainless steel, known as galvanization, is an industry standard to protect against corrosion. The zinc coating sacrificially corrodes, thereby protecting the stainless steel from corrosion [54–56]. Options are now being explored to withstand harsher conditions, longer lifetimes, reduced thickness and better overall strength of the protective coating layer. Although a large focus has been on the development of generalized corrosion resistant coatings, when considering cost, environmental impact and performance,

been successfully co-deposited with a number of materials including TiO2

, ZrO2

most commonly used reinforcement material for zinc-nickel coatings is Al2

/SiC, CeO2

, CeO2

O3

*i*

(ton = t

40°C

α-Al2 O3 ~30 nm 15 g/L 18 a/dm2

5, 10, 15 g/L 2 A/dm2

Alumina Sol 6 mL/L *i* DC = *i*

106 g/L ZINCATE 75 (75 g/L Zn and 400 g/L NaOH), 12 mL PERFORMA 285 Ni-CPL, 100 mL PERFORMA Additive K. 82.6 g/L NaOH, pH = 13

> . 7H2

O, 80 g/L Na2

, 250 g/L

BO3 ,

Cl,

O, 45 g/L H3

100 g/L KCl, 100 g/L NH4

0.1 g/L SDS, pH = 4

O, 35 g/L

SO4 ,

35 g/L ZnSO4

150 g/L ZnCl2

NiCl2 . 6H2

NiSO4 . 6H2

pH = 4

**deposition parameters**

, 23 ± 2°C

avg. = 80 mA/cm2

peak = 160 mA/cm2 Frequency (HZ) = 100 (ton = Toff = 5 ms), 500

off = 1 ms)

, 30°C

60 nm powder, S.A. 74 m2

/g

**Dispersion method**

, SiC, Al2

O3

, mica particles and polymeric nano-aggregates

/SiC with ~20% each, carbon nanotubes and

and Mt with ~4% each [11–13, 26–48].

O3

constituting

, PTFE

Ultrasonication and solution stirring during

Bath agitated 10 min prior to deposition.

Magnetic stirring 24 h prior to deposition, 500 rpm. Sonicated 2 h (500 W) (15 min on, 15 min off for 2 h). Magnetic stirring during deposition, 250 rpm simultaneously with sonication.

deposition.


Although several methods are available for the development of nanocomposite coatings, electrodeposition remains a favorable choice due to relative ease of use, low cost, convenience, ability to work at low temperatures and overall control of experimental parameters [39, 48, 58, 65]. A general survey of the literature concerning zinc-nickel nanocomposite coatings found electrochemical deposition to be the main preparation method, so general trends and properties of the

, SiO2

morillonite (Mt) have been successfully incorporated into zinc-nickel coatings. For optimal effect, the nanoparticles need to be dispersed throughout the metallic coating. To accomplish this, the particles first need to be suspended in the electrolytic solution and agglomeration of the particles needs to be kept to a minimum to prevent issues in coating formation. Particle agglomeration is an issue seemingly independent of particle concentration as it occurs under low to high concentrations, though smaller particle size does increase tendency to form agglomerations, leading to less incorporation in the final coating. To prevent agglomeration, various methods can be used such as organic additives, agitation of the solution, current density, etc. Treatment of the nanoparticles prior to deposition is varied throughout the field but the most common methods used for particle suspension are magnetic stirring, sonication or a combination of stirring and sonication prior to and during deposition [11–13, 26–48]. In addition to treatment of the nanoparticles, concentration in the bath also affects the quality of the coatings. As expected, as the concentration of nanoparticles in the bath increases, the concentration of nanoparticles in the resulting coating tends to increase. The small sized particles are easily incorporated into irregularities on the metal surface and positively charged particles are attracted to the cathode, so more easily incorporated into the coating [13]. In the case of oxide nanoparticles, the oxides compete with the metallic ions for adsorption onto the active sites, creating more nucleation sites and perturbing metallic grain growth. Other particles are trapped during deposition, filing holes or gaps within the naturally forming coating [22, 40]. Concentration of nanoparticles in the bath varies from 0.05–300 g/L with most work using around 5–15 g/L. Müller et al., who relied on mechanical stirring to disperse the nanoparticles, found optimal concentration of SiC particles to be 60 g/L, beyond which the particles began to agglomerate. Beyond this concentration, stirring was not sufficient to keep the particles suspended in solution and a decreasing trend of SiC in the coatings was observed [42].

Katamipour et al. studied the effects of ultrasonic conditions to promote uniform dispersion of the coating particles, and to determine if improvement occurred in the corrosion and mechanical properties of the coatings. They found that increasing the ultrasonic power density lead to a decrease in particle size, an increase in nanoparticle incorporation in the coating, and initially, an improvement in corrosion and mechanical properties. The agglomeration often observed with nanoparticles also dissipated with the use of sonication [36]. Nano-alumina

, SiC, ceria, carbon nanotubes and mont-

Electrodeposited Zinc-Nickel Nanocomposite Coatings http://dx.doi.org/10.5772/intechopen.80219 191

coatings formed through electrochemical methods will be the focus of this chapter.

**2. Electrodeposition of zinc-nickel nanocomposite coatings**

O3 , TiO2

**2.1. Dispersion of particles**

A variety of particles, including Al2

**Table 1.** Survey of literature.

zinc alloys have become an attractive option. An alloy modifies the composition of a material resulting in different corrosion properties then the original element which can significantly improve the stability of the protective coating [2–5, 52, 57, 58], therefore, by picking the correct combination of alloys, one can greatly increase the corrosion resistance of the material [49, 52]. Alloy formation can result in various phases, dependent upon the experimental conditions at the time of formation. For zinc-nickel, there are 5 known alloy phases: α- and β- (30% Ni, nickel rich), γ- (Ni5 Zn21), δ- (Ni3 Zn22) and η- (1% Ni) (zinc rich), all dependent upon the Zn/Ni ratio and experimental parameters used to form the alloy [50, 55, 59–61]. The γ-phase and δ-phase are predominantly formed through electrochemical methods, with γ-phase showing the strongest protection against corrosion [57, 60, 62–65]. Zinc nickel γ-phase alloys with approximately 8–18% have been found to be optimal for maximum corrosion protection [48, 57, 62, 65].

Although several methods are available for the development of nanocomposite coatings, electrodeposition remains a favorable choice due to relative ease of use, low cost, convenience, ability to work at low temperatures and overall control of experimental parameters [39, 48, 58, 65]. A general survey of the literature concerning zinc-nickel nanocomposite coatings found electrochemical deposition to be the main preparation method, so general trends and properties of the coatings formed through electrochemical methods will be the focus of this chapter.
