The effect of substrate on the electroless nickel plating of Mg and Mg alloys

Liu, Zhenmin; Gao, Wei

doi:10.1016/j.surfcoat.2004.12.001

Cited by 107 publications

(62 citation statements)

References 6 publications

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“…Furthermore, we found that the nucleation mechanism is also different. Apparently the traditional EN coating was preferentially nucleated on the b-phase or in the vicinity, resulting in non-uniform distribution [6,7,18]. On the contrary, the nucleation of the new EN processing is quite uniform on the PEO pre-treated surface from Fig.…”

Section: Resultsmentioning

confidence: 93%

“…The detailed operation conditions can be found elsewhere [16]. The conventional EN plating also was applied to AZ91 alloy, its detailed operation processes can be found elsewhere [7]. In order to compare the corrosion property of the two kinds of processes effectively, EN coatings with same thickness of 25 mm were plated onto AZ91 substrate after the two different pretreatments.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, study of EN coatings on Mg alloys has attracted much more attentions. So far, most of the literatures use CrO 3 , cyanide, and/or hydrofluoric acid during the pretreatment, which are harmful to the operators or unfriendly to the environment [1][2][3][4][5][6][7][8]. There are some new advance concerning the elimination of the above mentioned hazardous chemicals [9,10].…”

Section: Introductionmentioning

confidence: 99%

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A novel process of electroless Ni-P plating with plasma electrolytic oxidation pretreatment

Liu

Gao

2006

Applied Surface Science

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Section: Resultsmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A novel process of electroless Ni-P plating with plasma electrolytic oxidation pretreatment

Liu

Gao

2006

Applied Surface Science

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“…It was suggested that the kinetics of electroless nickel deposition on magnesium alloy substrates can be divided into three stages: first, an initial stage of approximately 0 to 10 minutes in which deposition is very slow; second, an acceleration period with an increasing deposition rate for up to 30 minutes of deposition; and third, a period in which the deposition rate starts to slow down again. [14] 2. Kinetics of EN-P deposition on magnesium alloy AZ31 coated with phosphate-permanganate conversion coating…”

Section: Effect Of Time On Thickness Of En-p Depositmentioning

confidence: 99%

Electroless Nickel Phosphorus Plating on AZ31

Shartal

Kipouros

2009

Metall Mater Trans B

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One of the major drawbacks to using magnesium parts in automotive applications is poor corrosion resistance, which can be improved with a nickel-boron coating placed on a nickelphosphorus coating, which, in turn, is placed on a phosphate-permanganate conversion-coating layer produced on the magnesium alloy AZ31. This work reports on the determination of the optimum kinetic parameters for producing a coherent nickel-phosphorus coating using an electroless-procedure phosphate-permanganate conversion-coating layer and for studying the effects of the experimental variables of the electroless plating process on the phosphorus content, surface morphology, and structure of the electroless nickel-phosphorus (EN-P) coatings produced. Measurements of the plating rate as a function of experimental variables such as the compositions of the plating bath constituents, temperature, and pH were implemented using the weight-gain method; the phosphorus content of the EN-P coatings was measured using energydispersive spectroscopy (EDS) analysis. The surface morphology of the coating was examined using a scanning electron microscope (SEM); X-ray diffraction (XRD) was used to characterize the structure of each coating. An empirical rate law was determined for EN-P plating on a phosphate-permanganate conversion coating. It is found that the deposition rate of the EN-P coating increases by increasing the deposition temperature, the concentration of free nickel ions, and the concentration of hypophosphite ions in the plating bath. In addition, the deposition rate decreases by increasing both the plating bath pH and the concentration of citric acid in the plating bath.

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“…11 However, acid pickling in a chromiumcontaining (VI) solution, followed by activation in a hydrofluoric acid solution is usually employed in the conventional pretreatment processes of direct ENP. [25][26][27][28][29][30] Several modified pretreatments have been devised to avoid the use of such process, which contains some species detrimental to the environment and harmful to human health. 11,[31][32][33] A method of avoiding the use of toxicant was carried out by employing a pre-plating step with an alkaline ENP bath prior to subsequent common ENP in an acidic bath.…”

mentioning

confidence: 99%

Studies of Several Pickling and Activation Processes for Electroless Ni-P Plating on AZ31 Magnesium Alloy

Xie

Chen

Xiang

et al. 2014

J. Electrochem. Soc.

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Several chromium-free pickling and activation processes were investigated in order to develop an eco-friendly pretreatment for electroless Ni-P plating on magnesium alloy. The coatings obtained from etching only in H 3 PO 4 solution exhibit poor adhesion due to the existance of an interlayer. Meanwhile, a corrosion model of Mg alloy in H 3 PO 4 solution was proposed. When fluoride was added into the pickling solution, the adhesion of the coatings was also unsatisfied because of the bad mechanical interlocking action. By comparison, the coatings obtained from pickling in H 3 PO 4 solution followed by NH 4 Magnesium (Mg) alloy is one of the lightest structural metals and a potential candidate to replace the heavier aluminum or steel in manufacturing of mechanic components due to its low density, excellent physical and mechanical properties. [1][2][3][4][5][6] However, the use of Mg alloy for structural applications has been limited owing to their poor corrosion resistance and high chemical reactivity. 7-12Electroless Ni-P plating (ENP) is one of the most effective surface treatment techniques to overcome the defect of Mg alloy, because ENP can provide excellent properties of hardness, good wear resistance and great corrosion resistance by forming a uniform deposit on the Mg alloy substrate surface. [13][14][15][16] However, ENP on Mg alloy presents many problems still because of the rapid formation of oxide film upon Mg alloy exposed to air/water, and forming loose immersion layers on the substrate surface by replacement reactions at the initial deposition stage. The loose oxide film and immersion layers hinder successful ENP and are detrimental to the adhesion and uniformity of subsequent coatings.17-20 Therefore, appropriate pretreatment steps must be taken before ENP to remove the natural oxide tarnish, embedded sand, heavy metal impurities and burned-in lubricants on the surface of the Mg alloy, and to activate the deposition of nickel on the matrix. [21][22][23] There are mainly two types of preferred pretreatments for Mg alloy, including zinc immersion and direct ENP.18,24 The direct ENP is simpler and more convenient.11 However, acid pickling in a chromiumcontaining (VI) solution, followed by activation in a hydrofluoric acid solution is usually employed in the conventional pretreatment processes of direct ENP. [25][26][27][28][29][30] Several modified pretreatments have been devised to avoid the use of such process, which contains some species detrimental to the environment and harmful to human health. 11,[31][32][33] A method of avoiding the use of toxicant was carried out by employing a pre-plating step with an alkaline ENP bath prior to subsequent common ENP in an acidic bath.31 Molybdate (MoO 4 2− ) chemical conversion coating was also attempted for replacing the chromium acid pickling. [32][33] In the work of Ref. 32, strong volatile hydrogen fluoride acid was applied in the activation process and the molybdate conversion bath contained carcinogenic NaNO 2 . 32 The adhesion, which is a very important...

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The effect of substrate on the electroless nickel plating of Mg and Mg alloys

Cited by 107 publications

References 6 publications

A novel process of electroless Ni-P plating with plasma electrolytic oxidation pretreatment

A novel process of electroless Ni-P plating with plasma electrolytic oxidation pretreatment

Electroless Nickel Phosphorus Plating on AZ31

Studies of Several Pickling and Activation Processes for Electroless Ni-P Plating on AZ31 Magnesium Alloy

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