Influence of Ti 3 C 2 T x addition on the corrosion behaviour and tribological properties of electrodeposited Ni-W-Ti 3 C 2 T x nanocomposite coatings

Abstract

Present study deals with the comparative wear and corrosion behaviour of electrodeposited Ni-W-Ti₃C₂T_x composite coatings. The composite coatings were prepared by direct current electrodeposition method in bath with different amounts of Ti₃C₂T_x. Reciprocating friction was used to analyse the wear behaviour of the coating. The corrosion resistance of all coatings was examined by potential polarisation and electrochemical impedance spectroscopy. The results show that the wear rate and friction coefficient are the lowest for Ni-W-20Ti₃C₂T_x composite coating among all the coatings, which is attributed to the lubrication effect of Ti₃C₂T_x. Moreover, the Ti₃C₂T_x can effectively improve the corrosion resistance of Ni-W alloy coating, and the optimum addition of 20 mg/L is reached, which is determined by Ni (111) texture and surface quality.

Keywords

Electrodeposition Corrosion performance Texture Hardness Wear behavior Microstructure Surface

Introduction

At present, surface treatment technology has been used in many fields [1 -3], electrodeposition is widely used in surface treatment because of its low cost and simple operation. It is also an important method to prepare metal matrix composites with excellent wear resistance and corrosion resistance. The Ni-W alloy coating has good mechanical properties, excellent tribological properties and corrosion resistance. Wasekar et al. [4,5] manipulated the tungsten content and grain size to obtain Ni-W coatings with excellent corrosion resistance and wear resistance. Because of these excellent performance, it serves as an ideal substitute for hard chromium coatings and is widely used in harsh environments [6 -9]. However, pure Ni-W alloy coatings have difficulty in adapting to complex environments. Therefore, the modification of pure Ni-W alloy coatings becomes extremely important. An important method to prepare composite coatings with excellent properties is the addition of nanoparticles [10 -14]. The nanoparticles affect the microstructure of the Ni-W matrix composite coating, including the grain size, texture and internal stress. In recent years, various particles have been added to Ni-W alloy coatings, e.g. Ni-W-SiC [15], Ni-W-GO [16], Ni-W-Al₂O₃ [17] and Ni-W-TiO₂ [18] composite coatings have been successfully prepared and have good properties.

Mxenes, which compose an emerging family of two-dimensional layered materials, are transition metal carbides and nitrides. They are usually obtained by the selective etching of ternaries of carbides or nitride compounds with hydrofluoric acid. Due to their graphene-like structure, Mxenes have attracted great attention and have been widely used in energy storage, electromagnetic shielding, lubrication and other fields [19 -23]. Naguib et al. [19] first produced Ti₃C₂T_x (T = OH and F) by etching Al from Ti₃AlC₂ in concentrated HF. Sinnott et al. [24] predicted that by calculation and research the coefficient of friction (COF) was 0.24–0.27 for Ti₃C₂T_x with a normal load of less than 1.2 GPa. Murat et al. [25] used the first principles to calculate that the elastic moduli of Ti₃C₂T_x was approximately 300 GPa. Furthermore, Ti₃C₂T_x has good stability and electrical properties [26 -30]. Due to its excellent physical and chemical properties, Ti₃C₂T_x has been widely applied in composite materials. In recent years, it has been found that Ti₃C₂T_x can significantly improve the mechanical properties of materials by combining with many polymer materials (such as PVA [31], PDDA [31], PEI [32] and UHMWPE [33]). Zhang et al. [33] found that the tensile strength, fracture strength, creep properties and friction reduction properties of Ti₃C₂/UHMWPE nanocomposites were significantly improved. Nie et al. [34] hybridised two-dimensional MXene (Ti₃C₂) sheets with the γ-glycidoxypropyl trimethoxysilane (γ-GPS) film on AA2024 aluminium alloy surface to improve the anticorrosion property. The Ti₃C₂T_x/silane composite designed by Cao et al. greatly improves the corrosion performance through the protective effect of Ti₃C₂T_x [35]. The disadvantages of polymer materials are insecure and poor wear resistance, Ti₃C₂T_x-doped metal matrix composites can avoid these problems and the electrodeposition method can make it more widely used in industry. It is reasonable to believe that the properties of Ti₃C₂T_x can also bring potential applications of metal matrix composites in the fields of wear resistance and corrosion resistance. However, there are few reports on the fabrication and characterisation of Ti₃C₂T_x-doped metal matrix composites.

In this work, Ni-W-Ti₃C₂T_x composite coatings with a low amount of Ti₃C₂T_x addition were first designed and synthesised by composite electrodeposition. Then, the relationships between the properties and structures of the Ni-W-Ti₃C₂T_x coatings were studied.

Experiment

Preparation of the Ti₃C₂T_x nanosheets and Ni-W-Ti₃C₂T_x composite coatings

With magnetic stirring, Ti₃AlC₂ (Figure 1(a)) was etched by self-prepared HF (10 M HCl + 2 M LiF) at 40 °C for 24 h, and a 3-g/L Ti₃C₂T_x suspension was obtained by centrifugation to prepare the composite coatings. The Ti₃C₂T_x nanosheets obtained by freeze-drying exhibit the morphology of a 2D material, as shown in Figure 1(b). Under DC power supplying and magnetic stirring, Ti₃C₂T_x, Ni⁺ and WO₄²⁻ compound formed a Ni-W-Ti₃C₂T_x coating. The specific schematic diagram is shown in Figure 1(c).

Figure 1

(a) SEM images of the typical morphologies of Ti₃AlC₂; (b) SEM images of the typical morphologies of Ti₃C₂T_x; (c) schematic diagram of the electrodeposition mechanism.

The anode for electroplating was a platinum plate (20 mm × 20 mm), and the cathode was a #45 steel plate (10 mm × 10 mm). A specimen with chemical composition of Fe-0.42C-0.17Si-0.5Mn-0.2Cr-0.35(Ni + Cu) (wt pct) was used for the electrodeposition. Prior to electrodeposition, the substrate was mechanically polished with different grades of abrasive papers (180-2000). Edges and corners of the substrate should also be rounded to eliminate the edge effect. The substrate was degreased with the mixtures of sodium-salt and OP-emulsifier to remove the oil contamination at a temperature of 75 °C, and activated for 60 s in 10 wt.% HCl. To evenly distribute the particles, solution flow/agitation was used, magnetic stirring was performed at a speed of 300 rpm for 24 h. The electroplating solution composition and plating process parameters in the experiments are shown in Table 1. For convenience, the Ni-W-Ti₃C₂T_x composite coatings obtained in different electrolytes were recorded as Ni-W-xTi₃C₂T_x, where x corresponds to the Ti₃C₂T_x concentration (mg/L) in the electrolyte (x = 0, 10, 20, 30, 40).

Table 1

Electrolyte composition and plating parameters to prepare the Ni-W-Ti₃C₂T_x composite coatings.

Composition	Content(g/L)	Plating parameters
NiSO₄·6H₂O	15	CD = 5 A/dm²
NaWO₄·2H₂O	50	pH = 9
Na₃Cit·H₂O	100	Time = 60 min
Na₂SO₄	40	Temperature = 60 °C
NH₄Cl	25
Sodium Lauryl Sulfate (SLS)	0.003
Ti₃C₂T_x	0, 0.01, 0.02, 0.03 and 0.04

Characterisation of the Ni-W-Ti₃C₂T_x composite coatings

X-ray diffractometer (X'Pert PRO PANalytical) with Cu-Kα radiation source (40 kV, 40 mA) was used to identify the phases of all the coatings. The scanning rate was 5° per minute in the 2θ range of 10–90°. The crystallite diameter of all the coatings was calculated by using the Debye-Scherrer formula from the X-ray diffraction spectrum. The calculation formula is as follows: (1) where is the grain size, is Scherer constant (typical value is 0.89), is the incident radiation of Cu (1.5418 Å), is the full-width half-maximum (FWHM) and is the diffraction angle.

The morphologies and compositions of all the coatings were measured by field-emission scanning electron microscopy (FESEM, MIRA3 LMH) with energy dispersive spectroscopy (EDS). The acceleration voltage selected by EDS was 20 keV, the beam spot size was approximately 4.44 nm, the emission current was 2 × 10⁻⁴ A and the dwell time was 1 × 10⁻⁵ s. Cross-sections of the coated samples were also analysed to clarify the effect of the Ti₃C₂T_x additive on the coating thickness. For repeatability, each test was performed on multiple areas of the sample. The corrosion products after electrochemical corrosion and immersion corrosion were analysed by X-ray photoelectron spectroscopy (XPS, Thermo Scientific K-Alpha) measurements and FESEM.

The microhardness of the Ni-W-Ti₃C₂T_x composite coatings under a 0.49-N load for 10 s was measured by a Vickers hardness tester (HV-1000). The microhardness is the average value of each sample in five different areas. The tribology of the composite coating was studied using a universal microtribotester (UMT-2). The friction dual ball was an Si₃N₄ ball with a diameter of 10 mm. Under the load of 3N, the reciprocating friction velocity was 25 mm/s, the reciprocating friction distance was 5 mm and the sliding motion was 60 min. The surface morphology and profile of the specimen after wear were observed via FESEM and confocal laser scanning microscopy (CLSM).

The electrochemical behaviour of the composite coating in 3.5 wt. % NaCl solution was tested using a CHI-760E electrochemical system. The working electrode, counter electrode and reference electrode are the composite coating, platinum electrode and saturated calomel electrode (SCE), respectively. Before the experiment, the electroplating sample was soaked in the electrolyte for 1000 s to obtain a steady open circuit potential (E_OCP). The corresponding corrosion current density and potential were collected from the galvanic potential polarisation curve in the sweeping range of −1 to 1 V. Electrochemical impedance spectroscopy (EIS) was measured on an E_OCP with an AC amplitude of 5 mV in the frequency range of 100 kHz to 10 MHz.

Results and discussion

Microstructure and morphology of the Ni-W-Ti₃C₂T_x composite coatings

Figure 2 shows the XRD profiles of all the coatings. The relative texture coefficient was calculated by evaluating the orientation mass as follows: (2) where and are the diffraction intensities of the (hkl) plane, which correspond to the Ni-W-Ti₃C₂T_x and Ni-W coatings, respectively.

Figure 2

(a) X-ray diffraction profiles of the Ni-W-Ti₃C₂T_x composite coatings with various additions of Ti₃C₂T_x; (b) RTC of the hkl planes in all the coatings.

Only the (111), (200) and (220) crystal planes of Ni were considered. RTC_(hkl) is the relative strength of the selected crystal planes of all the coatings. When RTC_(hkl) ≥ 33.33%, the crystal planes of (hkl) have a preferred orientation. The diffraction peak intensity of all the coatings are shown in Table 2.

Table 2

Heights of the (111), (200) and (220) peaks.

	(111)	(200)	(220)
Ni-W	728	138	104
Ni-W-10Ti₃C₂T_x	4308	99	80
Ni-W-20Ti₃C₂T_x	9627	86	69
Ni-W-30Ti₃C₂T_x	6630	88	65
Ni-W-40Ti₃C₂T_x	5963	122	94

The XRD pattern contained only the nickel phase, which indicates that the coating is a nickel-based solid solution (see Figure 2(a)). The results show that the characteristic peaks appear at 44.15°, 51.13° and 75.58°, which correspond to the (111), (200) and (220) crystal planes of nickel, respectively. However, since only a small amount of Ti₃C₂T_x is in the coating, the corresponding characteristic peak does not appear in the XRD pattern. The grain size of the composite coatings can be calculated by Debye Sherrer's equation and the values are given in Table 3.

Table 3

FWHM and height of the Ni(111) peak.

	0 mg/L	10 mg/L	20 mg/L	30 mg/L	40 mg/L
FWHM	0.835	0.425	0.391	0.404	0.400
Height	728	4308	9627	6630	5963
Grain size (nm)	10.3	20.8	22.7	21.9	22.1
Angle (°)	44.146	44.046	43.998	43.985	44.039

As shown in Figure 2(b), of the Ni-W coating was 33.33%, which represents the free orientation of the coating. The Ni-W-Ti₃C₂T_x coating had a much larger than the Ni-W alloy coating. Furthermore, first increased and subsequently decreased, which indicates that the addition of Ti₃C₂T_x made the Ni-W-Ti₃C₂T_x composite coating have a strong (111) fibre texture. The texture of thin films and coating materials is usually strongly controlled by their surface energies [36]. For fcc metals, the (111) texture is generally formed because it is a dense arrangement with the lowest surface energy compared to other textures. Thus, the addition of Ti₃C₂T_x may minimise the surface energy. Additionally, the Ti₃C₂T_x lattice can adsorb Ni atoms. When the maximum number of Ni atoms is adsorbed, they naturally appear in a dense arrangement. Although there was a slight mismatch in lattice constants, it was easy to observe this densely arranged structure during the deposition process, which inevitably caused the selective growth of crystal surfaces during metal growth. Therefore, Ti₃C₂T_x can promote Ni atoms to form a similar line in the structure, which provides a basis for the subsequent deposition of Ni atoms to suppress the (111) surface structure. Since the (111) plane was formed by electrodeposition, excess Ti₃C₂T_x agglomerated, and the closure of Ti₃C₂T_x nanocrystals affected the growth of the metal matrix; thus, the preferred growth was weakened.

The SEM analysis of the as-obtained Ni-W coatings without Ti₃C₂T_x nanosheets shows that the microstructure of the coating was nodular (see Figure 3(a)). All the coatings had crystal structures, and there are obvious diffraction peaks in the XRD pattern, which indicates that the addition of Ti₃C₂T_x did not affect the crystal structure of the coating. In contrast, the coatings containing Ti₃C₂T_x showed uniform and smooth surfaces (Figure 3(b,d)). Additionally, Ti₃C₂T_x exhibited a uniform distribution. The coating with 20 mg/L Ti₃C₂T_x had larger grain sizes than those with 0 and 40 mg/L Ti₃C₂T_x. The high magnification of the Ni-W-20Ti₃C₂T_x deposit and EDS spectrum of the appointed area are shown in Figure 3(c,f). The surface of the Ni-W-40Ti₃C₂T_x sample had nanosheet agglomeration, which is typical of Ti₃C₂T_x. The Ti₃C₂T_x nanosheets of the Ni-W-20Ti₃C₂T_x composite coatings were uniformly distributed, but the content was low.

Figure 3

Surface micrographs of the composite coatings: (a) Ni-W; (b) Ni-W-20Ti₃C₂T_x; (c) higher magnification of (b); (d) Ni-W-40Ti₃C₂T_x; (e) higher magnification of (d); (f) EDS spectrum of the appointed area in (c).

Figure 4 shows the cross-sectional morphology and linear EDS results of all deposits. The analysis shows that the interface between all the coatings and substrates was clear and tightly bonded. The coating thickness shows that the addition of an appropriate amount of Ti₃C₂T_x had no negative impact on the deposition efficiency. When more than 40 mg/L Ti₃C₂T_x was added, the coating thickness decreased due to the negative impact of Ti₃C₂T_x agglomeration on the electrodeposition efficiency, which indicates a particle saturation limit in the bath. Furthermore, the linear EDS analysis implies that Ni and W were the main elements in the Ni-W-Ti₃C₂T_x coatings.

Figure 4

SEM images of the cross-section and linear EDS of all the coatings: (a) Ni-W, (b) Ni-W-10Ti₃C₂T_x, (c) Ni-W-20Ti₃C₂T_x, (d) Ni-W-30Ti₃C₂T_x and (e) Ni-W-40Ti₃C₂T_x.

Effect of the Ti₃C₂T_x addition on the hardness

The effect of the Ti₃C₂T_x addition on the hardness of all the coatings is shown in Figure 5. Compared to the coating without Ti₃C₂T_x, adding Ti₃C₂T_x can significantly improve the microhardness of the deposit. In detail, the microhardness of the Ni-W-Ti₃C₂T_x sample was 631.36 HV, when the addition amount was 20 mg/L. The nucleation and growth kinetics of the Ni-W matrix were changed by adding different amounts of Ti₃C₂T_x nanosheets into the Ni-W matrix; this addition was expected to cause lattice distortion and increase the hardness of the matrix. The hard particles in the matrix are usually beneficial to improve the overall microhardness of the composites [37]. As a hard phase, Ti₃C₂T_x was added into the alloy coating to prevent the dislocation slip and achieve dispersion strengthening. However, when the addition amount of Ti₃C₂T_x was too high, some agglomeration might occur and affect the deposition efficiency, which reduced the combination between Ti₃C₂T_x and the matrix metal, and consequently reduced the microhardness, Singh et al. prepared the Ni-TiC composite coating to have the similar situation [37]. The hardness data shown in Table 4 are related to the addition of various inert particles to Ni-W alloy coatings. It can be observed that these composite coatings usually have hardness values ranging from 500 to 1000 HV. For better wear resistance, the hardness of the coating is best in the 600–1000 HV range, which corresponds to the hardness of a typical hard chromium coating. Although the addition of Ti₃C₂T_x has no outstanding strengthening effect, its two-dimensional structure has an important effect on the composite coating.

Figure 5

Microhardness of the Ni-W-Ti₃C₂T_x composite coatings

Table 4

Hardness with respect to particle of various Ni-W composite coatings from literature.

Materials	Method	Hardness
Ni-W-Ti₃C₂T_x	DC	631.36 HV
Ni-W-SiC [15]	PC	1000 HV
Ni-W-GO [16]	DC	542-688 HV
Ni-W-Al₂O₃ [17]	PC	670-805 HV
Ni-W-TiO₂ [18]	DC+PC	467-686 HV

Tribological performances of the Ni-W-Ti₃C₂T_x composite coatings

Figure 6 shows the COF curve and average COF of all the coatings under a 3-N load at 25 °C. In the beginning, the COF of all the coatings was low. After 10 min, the COF of the coating remained relatively stable until the end of the test. Figure 6 shows that the addition of Ti₃C₂T_x could effectively reduce the COF of the coating. Figure 6(a) shows that the Ni-W coating had the largest COF, while the composite coating prepared by adding 20 mg/L Ti₃C₂T_x had the smallest COF. The wear rate of all coatings are shown in Figure 6(c). Ni-W alloy coatings have the highest wear rate of 2.293 × 10⁻⁶•mm³•N⁻¹•m⁻¹. The Ni-W-Ti₃C₂T_x composite coatings with 20 mg/L Ti₃C₂T_x addition has the lowest wear rate (0.865 × 10⁻⁶•mm³•N⁻¹•m⁻¹), which is only 37.72% that of Ni-W alloy coating.

Figure 6

COF of all the composite coatings: (a) COF curve, (b) average COF and (c) Wear rate.

To further reveal the wear condition, the morphologies of the 2D and 3D wear marks are shown in Figures 7 and 8, respectively. Under identical experimental conditions, the widths of the grinding cracks on all the coatings were approximately identical. However, Figure 10(a) shows obvious cracks and many chips on the worn surface of the Ni-W deposit. The addition of Ti₃C₂T_x improved the deposition, especially the worn surface of the Ni-W-20Ti₃C₂T_x and Ni-W-30Ti₃C₂T_x deposits, which contained little wear debris and showed a shallow groove (Figures 9 and 10).

Figure 7

Profile of the wear track on all the coatings.

Figure 8

3D profiles of the wear track on all the coatings: (a) Ni-W, (b) Ni-W-10Ti₃C₂T_x, (c) Ni-W-20Ti₃C₂T_x, (d) Ni-W-30Ti₃C₂T_x, and (e) Ni-W-40Ti₃C₂T_x.

Figure 9

SEM images of the worn surface morphologies of all the coatings: (a) 0 mg/L, (b) 10 mg/L, (c) 20 mg/L, (d) 30 mg/L, and (e) 40 mg/L.

Figure 10

Morphology of the wear track on all the coatings: (a) 0 mg/L, (b) 10 mg/L, (c) 20 mg/L, (d) 30 mg/L, and (e) 40 mg/L.

The above analysis shows that the dominant abrasion mechanisms were adhesive. Ti₃C₂T_x has the excellent wearability and self-lubrication. Ti₃C₂T_x plays the role of solid lubricant in the separation from the matrix and reduces the direct contact between the friction pair and the matrix, which decreases the COF. Additionally, the embedded Ti₃C₂T_x in the Ni-W coating can provide a second-phase enhancement to harden the coating. According to Archard theory, the tribological property of composites is proportional to the hardness [38]. In conclusion, the addition of Ti₃C₂T_x can provide the composite coating with excellent wear resistance and good self-lubricating effect.

Corrosion behaviour of composite coatings

Nyquist and polarisation curves were used to evaluate the effect of Ti₃C₂T_x on the corrosion performance of all deposits. The Tafel patterns of all deposits in the 3.5 wt.% NaCl solution are shown in Figure 11(a). The similarity of the potentiodynamic polarization (PDP) curves of the two deposits indicates the same corrosion protection mechanism. The deposits (the Ti₃C₂T_x addition is 10, 20 and 30 mg/L) had higher corrosion potential than those without Ti₃C₂T_x but lower corrosion potential than the composite coating with a higher Ti₃C₂T_x content (40 mg/L) due to the agglomeration of Ti₃C₂T_x. Therefore, the information in Table 5 confirms that the minimum corrosion current density (5.355 × 10⁻³ mA/cm²) of the Ni-W-20Ti₃C₂T_x deposit indicates good corrosion resistance.

Figure 11

(a) PDP, (b) EIS and (c) Bode curves of all the coatings in a 3.5 wt.% NaCl solution.

Table 5

Electrochemical corrosion results of the Ni-W-Ti₃C₂T_x coatings deposited with different Ti₃C₂T_x additions.

Ti₃C₂T_x addition (mg/L)	Corrosion current density (mA cm⁻²)	Corrosion potential (mV)
0	1.347 × 10⁻²	−686
10	3.951 × 10⁻²	−534
20	5.355 × 10⁻³	−633
30	2.221 × 10⁻²	−667
40	1.319 × 10⁻²	−691

The Nyquist plots of all deposits showed arcs of different radii, which can help to directly evaluate the corrosion resistance of the coating (Figure 11(b)). Figure 11(b) also contains the equivalent circuit obtained by fitting the impedance results. The solution resistance (R_s), charge transfer resistance (R_ct), and constant phase element (CPE) were considered [39 -41]. The electrochemical impedance fitting data are listed in Table 6. The CPE can be calculated as follows: (3)

where

is the CPE index,

is the admittance constant, and

is the imaginary corner frequency

. When the Ti₃C₂T_x addition increased from 0 to 20 mg/L, R_ct significantly increased from 12.69 to 31.93 kΩ cm², while

increased from 0.8644 to 0.9307, which indicates the enhanced corrosion resistance. Furthermore, in the phase angle diagram (Figure 11(c)), the Ni-W-20Ti₃C₂T_x deposit showed a wider platform in the high to medium frequency range. The phase angle of Ni-W-20Ti₃C₂T_x deposit increased significantly, which indicated that the deposits exhibited a smaller capacitance value. These results indicate that the Ni-W-20Ti₃C₂T_x deposit gave a much better corrosion resistance than other coatings.

Table 6

Electrochemical fitting data of the Ni-W-Ti₃C₂T_x coatings deposited with different Ti₃C₂T_x additions

		CPE
Ti₃C₂T_x addition (mg/L)	R_s (Ω cm⁻²)	Y₀ (Ω⁻¹ cm⁻²Sⁿ)		R_ct (kΩ cm⁻²)
0	4.47	6.1953 × 10⁻⁵	0.8644	12.69
10	4.7	6.5604 × 10⁻⁵	0.8222	24.84
20	3.023	5.0372 × 10⁻⁵	0.9307	31.93
30	2.384	6.0821 × 10⁻⁵	0.8672	21.87
40	2.816	8.3034 × 10⁻⁵	0.8397	18.01

SEM and EDS were used to clearly analyse the corrosion products of the deposits. The microstructures of the Ni-W, Ni-W-20Ti₃C₂T_x and Ni-W-40Ti₃C₂T_x deposits after polarisation in 3.5 wt.% NaCl electrolyte were recorded (Figure 12). The main morphological feature of the Ni-W coating was the uneven local corrosion. Corrosion might start from pitting, which made the corrosion uneven and produces defects in the corrosion product film. Due to the precipitation of hydrogen, the uneven surface could be the dominating cause of pitting corrosion, and it easily dissolved during pitting corrosion. Thus, the corrosion products would continue to penetrate and spread. In the Ni-W-20Ti₃C₂T_x composite coating, fewer corrosion pits were observed. The composition analysis of the corrosion pits shows that the Ni-W deposit and Ni-W-40Ti₃C₂T_x deposit were electrochemically corroded to the bare substrate, while the main composition of the Ni-W-20Ti₃C₂T_x composite coating was nickel and tungsten. This result indicates that the passivation film formed by the Ni-W-20Ti₃C₂T_x composite coating was uniform and compact.

Figure 12

Surface morphologies of Ni-W (a), Ni-W-20Ti₃C₂T_x (d) and Ni-W-40Ti₃C₂T_x (e). The corresponding EDS results (h) in the embedded table contain the EDS results (wt.%).

Immersion corrosion behaviour of the composite coatings

Figure 13 shows the surface morphologies and EDS analysis of the Ni-W and Ni-W-20Ti₃C₂T_x coatings soaked in 3.5 wt.% NaCl electrolyte for 240 h. The corrosion products of the pure Ni-W alloy coating were loose, thick and even peeled off, which resulted in an exposed substrate (Figure 13(a)). The corrosion products of the Ni-W-20Ti₃C₂T_x composite coating were relatively thin and compact (Figure 13(d,e)), which were beneficial for protecting the substrate. This result suggests that Ti₃C₂T_x obviously affected the surface microstructure of the corrosion products.

Figure 13

SEM images and EDS results of the Ni-W (a, b and c) coating and Ni-W-20Ti₃C₂T_x (d, e) composite coating after immersion in a 3.5 wt.% NaCl solution for 10 days.

Figure 14 summarises the complete XPS spectra of the Ni-W and Ni-W-20Ti₃C₂T_x coatings soaked in 3.5 wt.% NaCl electrolyte for 240 h. The fitting results show that the dominant elemental compositions of the passive films were O, W and Ni. Table 6 shows that the Ni-W-20Ti₃C₂T_x composite coating had weaker Ni and W signals than the single Ni-W coating, which illustrates that the corrosion degree of Ni-W-20Ti₃C₂T_x was weakened. Figure 15(a,b) shows the Ni 2p spectra of the corrosion product layer, and the corrosion products were Ni(OH)₂ and NiO. Thus, Ni could be transformed to NiO and Ni(OH)₂ during erosion, and two layers were produced on the etched surface, where the inner layer was NiO, and the outer layer was Ni(OH)₂. The data in Table 7 show that the Ni and W contents in the Ni-W-20Ti₃C₂T_x composite coating decreased, which indicates that the corrosion degree decreased, and a thick and dense oxide film was produced on the surface.

Figure 14

Full XPS spectra of the surfaces of the Ni-W coating and Ni-W-20Ti₃C₂T_x composite coating after immersion in a 3.5 wt.% NaCl solution for 10 days.

Figure 15

XPS spectra of the (a, b) Ni 2p, (c, d) O 1s and (e, f) W 4f peaks of the passive films formed on the (a, c, e) Ni-W coating and (b, d, f) Ni-W-20Ti₃C₂T_x composite coating in a 3.5 wt.% NaCl solution.

Table 7

Fitted parameters of the O 1s, Ni 2p and W 4f XPS spectra.

Ni-W	Binding energy (eV)	FWHM (eV)	Area (keV)	Ni-W-20Ti₃C₂T_x	Binding energy (eV)	FWHM (eV)	Area (keV)
O 1s	531.07	2.63	1351.08	O 1s	531.15	2.65	1474.38
Ni 2p	855.91	3.34	1626.93	Ni 2p	855.99	3.18	1618.43
W 4f	35.27	0.78	21.75	W 4f	34.97	1.19	14.08

The corrosion resistance of the deposit was improved after 20 mg/L Ti₃C₂T_x was added, which corresponded to the quality of the corrosion product film. Although the Ni-W-20Ti₃C₂T_x composite coating had a larger crystallite dimension than the pure Ni-W coating, the surface was more uniform. An increase in grain size can also reduce the resistance to intergranular corrosion. Based on these results, excellent corrosion properties were obtained.

To illuminate the effect of the grain size on the oxidation rate, the effective diffusion coefficient can be calculated as follows [42]: (4) (5) where is the lattice diffusion coefficient, is the grain boundary diffusion coefficient, is the grain boundary area percentage, is the grain boundary width (0.5 nm) and is the mean crystallite size of the coating. According to a report, the grain boundary activation energy is much larger than the crystal lattice activation energy. In other words, is much larger than ; in general, [42].

The metal oxidation process is often controlled by the diffusion process of oxide films. Diffusion occurred due to various defects in the oxide, and diffusion along the grain boundaries was faster than the lattice diffusion. Additionally, the grain boundaries easily formed galvanic corrosion cells with the grains. The above formula shows that the proportion of diffusion along grain boundaries significantly decreased when the grain size increased; therefore, the corrosion rate decreased, and a compact oxidation film was formed. Similarly, due to the accelerated corrosion rate and thinner coating thickness of the Ni-W coating, the oxidation film was loose and thin, and some areas even corroded the matrix.

According to this discussion, the oxidation mechanism of the Ni-W and Ni-W-20Ti₃C₂T_x coatings was established. The two coatings showed identical oxidation behaviours, and corrosion preferably occurred at the grain boundaries. When the final corrosion product of Ni(OH)₂ was formed, a passivation film was generated on the surface. Schematic models of the oxidation mechanisms of the Ni-W coating and Ni-W-20Ti₃C₂T_x composite coatings with coarse and fine grain sizes are shown in Figure 16.

Figure 16

Schematic models of the oxidation mechanisms of the Ni-W coating and Ni-W-20Ti₃C₂T_x composite coating with coarse and fine grain sizes.

In addition to the grain size, the effect of the preferred orientation on the oxidation and corrosion resistance of metals could not be ignored. Lu et al. found that the Ni(111) crystal surface had significantly lower corrosion rate than Ni(200) [43]. Zhang et al. found that the addition of ZrC affected the texture of Ni plating [44]. The intergranular corrosion properties of the coatings were enhanced by changing the texture of the coatings, and the percentage of low-energy grain boundaries was increased by adding Ti₃C₂T_x. One of the main theories to explain the corrosion behaviour depends on the crystal orientation due to the density of atoms accumulated on the crystal surface. In other words, a higher atomic density on the surface corresponds to higher atomic coordination; thus, with stronger atomic bonding, the surface is more resistant to corrosion in a corrosive medium. Ni(111) had a greater surface atom density than Ni(200) and Ni(220), so Ni(111) also had a lower corrosion rate than these two crystal surfaces. Ti₃C₂T_x was used to enhance the texture of Ni(111), and the densest (111) plane had the lowest surface energy; therefore, the surface became denser. Figure 2(b) shows that the Ni-W-20Ti₃C₂T_x composite coating has the strongest Ni (111) preferred orientation.

Through the above analysis, crystal plane orientation, surface quality and grain size have a decisive effect on the corrosion resistance of coatings. Therefore, Ni-W-20Ti₃C₂T_x composite coating has the best corrosion resistance.

In this experiment, the microstructure of the composite coating was affected by adding Ti₃C₂T_x nanosheets. With the addition of Ti₃C₂T_x nanosheets, the surface of the coating became smoother, grain size increased, and the texture of Ni(111) was enhanced, which provided conditions to improve the corrosion resistance of the composite coating. Compared to the pure Ni-W coating, the hardness of the composite coating increased by 123.48 HV due to dispersion strengthening and solid solution strengthening. The COF and wear rate of the composite coating decreased due to the self-lubricating effect and strengthening effect of the Ti₃C₂T_x nanosheets.

Conclusion

In the present work, Ni-W-Ti₃C₂T_x composite coatings with different Ti₃C₂T_x additions were deposited by direct current electrodeposition method, and their mechanical, tribological and corrosion properties were systematically evaluated. The main conclusions drawn from the current survey are

Compared with Ni-W alloy coating, the hardness, wear resistance and corrosion resistance of Ni-W-Ti₃C₂T_x composite coatings are obviously improved.

Among all the coatings, Ni-W-20Ti₃C₂T_x composite coating has the lowest friction coefficient and wear rate, which is consistent with the highest hardness of Ni-W-20Ti₃C₂T_x composite coatings. Friction reduction mechanism is mainly Ti₃C₂T_x as a solid lubricant to prevent the metal matrix and friction pair contact.

Ni-W-20Ti₃C₂T_x composite coating has the lowest corrosion current density and the largest impedance arc radius, which depends on the enhancement of Ni(111) texture and the uniform distribution of Ti₃C₂T_x, forming a uniform and dense passivation film on the surface of the coating.

Footnotes

Disclosure statement

No potential conflict of interest was reported by the authors.

References

Zhang

Dai

Zhu

Bimetallic nitride modified separator constructs internal electric field for high-performance lithium-sulfur battery. Chem Eng J. 2022; 429:132454.

Gong

Jiang

Z-scheme heterojunction through interface engineering for broad spectrum photocatalytic water splitting. Appl Catal B. 2020; 267:118661.

Zheng

Zhang

Fan

In situ construction of aramid nanofiber membrane on Li anode as artificial SEI layer achieving ultra-high stability. Small. 2021; 17:2102347.

Wasekar

Hebalkar

Jyothirmayi

Influence of pulse parameters on the mechanical properties and electrochemical corrosion behavior of electrodeposited Ni-W alloy coatings with high tungsten content. Corros Sci. 2019; 165:108409.

Wasekar

Sundararajan

Sliding wear behavior of electrodeposited Ni–W alloy and hard chrome coatings. Wear. 2015; 342-343:340–348.

Salehikahrizsangi

Raeissi

Karimzadeh

Highly hydrophobic Ni-W electrodeposited film with hierarchical structure. Surf Coat Technol. 2018; 344:626–635.

Armstrong

DEJ

Haseeb

ASMA

Roberts

Nanoindentation and micro-mechanical fracture toughness of electrodeposited nanocrystalline Ni-W alloy films. Thin Solid Films. 2012; 520:4369–4372.

Beltowska-Lehman

Indyka

Bigos

Electrodeposition of nanocrystalline Ni-W coatings strengthened by ultrafine alumina particles. Surf Coat Technol. 2012; 211:62–66.

Chen

Lian

Liu

Recent research and development of thick CVD tungsten coatings for fusion application. Tungsten. 2020; 2:83–93.

10.

Wang

Zhang

Wang

JD.

Ni-SiC composite coatings with improved wear and corrosion resistance synthesized via ultrasonic electrodeposition. Ceram Int. 2021; 47(7):9437–9446.

11.

Alizadeh

Safaei

Characterization of Ni-Cu matrix, Al₂O₃ reinforced nano-composite coatings prepared by electrodeposition. Appl Surf Sci. 2018; 456:195–203.

12.

Xue

Lei

Wang

Effect of pulse duty cycle on mechanical properties and microstructure of nickel-graphene composite coating produced by pulse electrodeposition under supercritical carbon dioxide. Surf Coat Technol. 2017; 325:417–428.

13.

Zhou

Mai

Ling

Electrodeposition of CNTs/copper composite coatings with enhanced tribological performance from a low concentration CNTs colloidal solution. Mater Res Bull. 2017; 97:537–543.

14.

McManus

Ilhan

Balsamo

Synthesis of tungsten ditelluride thin films and highly crystalline nanobelts from pre-deposited reactants. Tungsten. 2020; 2:321–334.

15.

Wasekar

Bathini

Ramakrishna

Pulsed electrodeposition, mechanical properties and wear mechanism in Ni-W/SiC nanocomposite coatings used for automotive applications. Appl Surf Sci. 2020; 527:146896.

16.

Zhang

Liu

Preparation and tribological behavior of electrodeposited Ni-W-GO composite coatings. Rare Met. 2019; 38:695–703.

17.

Allahyarzadeh

Aliofkhazraei

Sabour

Electrodeposition of Ni-W-Al₂O₃ nanocomposite coating with functionally graded microstructure. J Alloy Compd. 2016; 666:217–226.

18.

Kumar

Kalaignan

Muralidharan

VS.

Direct and pulse current electrodeposition of Ni-W-TiO₂ nanocomposite coatings. Ceram Int. 2013; 39:2827–2834.

19.

Naguib

Kurtoglu

Presser

Two-dimensional nanocrystals produced by exfoliation of Ti₃AlC₂ . Adv Mater. 2011; 23:4248–4253.

20.

Wang

Sun

Synthesis and thermal stability of two-dimensional carbide MXene Ti₃C₂ . Mater Sci Eng B. 2015; 191:33–40.

21.

Ghidiu

Naguib

Shi

Synthesis and characterization of two-dimensional Nb₄C₃ (MXene). Chem Commun. 2014; 50:9517–9520.

22.

Halim

Kota

Lukatskaya

Synthesis and characterization of 2D molybdenum carbide (MXene). Adv Funct Mater. 2016; 26:3118–3127.

23.

Urbankowski

Anasori

Makaryan

Synthesis of two-dimensional titanium nitride Ti₄N₃(MXene). Nanoscale. 2016; 8:11385–11391.

24.

Zhan

Ashton

Ostadhossein

Computational study of low interlayer friction in Ti_n+1C_n (n = 1, 2, and 3) MXene. ACS Appl Mater Interfaces. 2017; 9:34467–34479.

25.

Kurtoglu

Naguib

Gogotsi

First principles study of two-dimensional early transition metal carbides. MRS Commun. 2012; 1:1–5.

26.

Wang

Zhou

Fabrication and thermal stability of two-dimensional carbide Ti₃C₂ nanosheets. Ceram Int. 2016; 42:8419–8424.

27.

Naguib

Mashtalir

Carle

Two-dimensional transition metal carbides. ACS Nano. 2012; 6:1322–1331.

28.

Naguib

Kurtoglu

Presser

Two-dimensional nanocrystals produced by exfoliation of Ti₃AlC₂ . Adv Mater. 2011; 23:4248–4253.

29.

Shein

Ivanovskii

Graphene-like titanium carbides and nitrides Ti_n+1C_n, Ti _n+1N_n (n = 1, 2, and 3) from de-intercalated MAX phases: firstprinciples probing of their structural, electronic properties and relative stability. Comput Mater Sci. 2012; 65:104–114.

30.

Khazaei

Arai

Sasaki

Novel electronic and magnetic properties of two-dimensional transition metal carbides and nitrides. Adv Funct Mater. 2013; 27:2185–2192.

31.

Ling

Ren

Zhao

MQ.

Flexible and conductive MXene films and nanocomposites with high capacitance. Proc Natl Acad Sci. 2014; 111:16676–16681.

32.

Hao

Zhang

Polymer-Ti₃C₂T_x composite membranes to overcome the trade-off in solvent resistant nanofiltration for alcohol-based system. J Membr Sci. 2016; 515:175–188.

33.

Zhang

Wang

Chen

Preparation, mechanical and anti-friction performance of MXene/polymer composites. Mater Des. 2016; 92:682–689.

34.

Wang

Schuetzenduebe

Qiu

Tailoring metal film texture by use of high atomic mobility at metal-semiconductor interfaces. Appl Surf Sci. 2018; 475:117–123.

35.

Cao

Fang

Jia

Remarkable improvement of corrosion resistance of silane composite coating with Ti₃C₂T_x MXene on copper. Compos Part B. 2022; 228:109427.

36.

Singh

VB.

Electrodeposition and characterization of Ni-TiC composite using N-methylformamide bath. Mater Sci Eng: A. 2012; 532:493–499.

37.

Nie

Huang

MXene-hybridized silane films for metal anticorrosion and antibacterial applications. Appl Surf Sci. 2020; 527:146915.

38.

Archard

JF.

Contact and rubbing of flat surfaces. J Appl Phys. 1953; 24:981–988.

39.

Chen

Zou

Study on self-healing and corrosion resistance behaviors of functionalized carbon dot-intercalated graphene-based waterborne epoxy coating. J Mater Sci Technol. 2021; 67:226–236.

40.

Liu

Superhydrophobic oligoaniline-containing electroactive silica coating as pre-process coating for corrosion protection of carbon steel. Chem Eng J. 2018; 348:940–951.

41.

Wang

Zheng

Zhu

JW.

Semi-conductive properties of passive films formed on copper in chromate solutions. Thin Solid Films. 2009; 517:1995–1999.

42.

Peng

Yan

Zhou

Effect of grain refinement on the resistance of 304 stainless steel to breakaway oxidation in wet air. Acta Mater. 2005; 53:5079–5088.

43.

Luo

Ren

Corrosion mechanism of Ni deposits on magnets by pulse current electro-deposition. Surf Coat Technol. 2021; 409(11):126833.

44.

Zhang

Jiang

Liao

Effect of electrodeposition parameters on the evolution of crystallographic texture and internal stress of Ni/ZrC composite coatings. Mater Today Commun. 2021; 27:102403.

Influence of Ti 3 C 2 T x addition on the corrosion behaviour and tribological properties of electrodeposited Ni-W-Ti 3 C 2 T x nanocomposite coatings

Abstract

Keywords

Introduction

Experiment

Preparation of the Ti3C2Tx nanosheets and Ni-W-Ti3C2Tx composite coatings

Characterisation of the Ni-W-Ti3C2Tx composite coatings

Results and discussion

Microstructure and morphology of the Ni-W-Ti3C2Tx composite coatings

Effect of the Ti3C2Tx addition on the hardness

Tribological performances of the Ni-W-Ti3C2Tx composite coatings

Corrosion behaviour of composite coatings

Immersion corrosion behaviour of the composite coatings

Conclusion

Footnotes

References

Preparation of the Ti₃C₂T_x nanosheets and Ni-W-Ti₃C₂T_x composite coatings

Characterisation of the Ni-W-Ti₃C₂T_x composite coatings

Microstructure and morphology of the Ni-W-Ti₃C₂T_x composite coatings

Effect of the Ti₃C₂T_x addition on the hardness

Tribological performances of the Ni-W-Ti₃C₂T_x composite coatings