A study of chromium-free pickling process before electroless Ni–P plating on magnesium alloys

Lei, Xiping; Yu, Gang; Gao, Xiang; Ye, Liyuan; Zhang, Jun; Hu, Bonian

doi:10.1016/j.surfcoat.2011.02.051

Cited by 32 publications

(21 citation statements)

References 24 publications

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“…An alternative and more recent approach is the direct electroless process, which can be described as follows [6,7]: mechanical polishing → degreasing in an alkaline solution → pickling in CrO 3 + HNO 3 solution → activation in HF solution → electroless plating in fluoride-containing bath.…”

Section: Introductionmentioning

confidence: 99%

Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

Seifzadeh

Mohsenabadi

2017

Bull Mater Sci

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Cerium-vanadium (Ce-V) conversion coating was proposed as a new pretreatment for application of electroless NiP coating on AM60B magnesium alloy to replace the traditional chromium oxide pretreatment. Morphology and chemical composition of the conversion coating were investigated. The subsequent NiP coating deposited on the conversion coating was also characterized by morphology, chemical composition, microstructure, corrosion protection performance and micro-hardness. A uniform, compact and pore-free electroless coating with a moderate concentration of phosphorus (7.78 wt%) was obtained. The electroless coating showed a nobler opencircuit potential than that of the bare alloy during the first 13 h of immersion in 3.5 wt% NaCl solution. Also, the sample plated with the Ce-V conversion coating showed lower corrosion current density than the sample plated with traditional chromium oxide pretreatment. The micro-hardness of the bare alloy was significantly increased after electroless coating. The electroless coating is pore-free and there is suitable adhesion between the coating and alloy substrate.

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Section: Introductionmentioning

confidence: 99%

Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

Seifzadeh

Mohsenabadi

2017

Bull Mater Sci

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“…However, further increase in H 3 PO 4 concentration will result in a higher concentration of PO 3− 4 , leading to a higher tendeny to produce insoluble films (mainly Mg 3 (PO 4 ) 2 and AlPO 4 ). 22,39 These insoluble films deposited on the surface of the substrate and slow down the rate of Mg alloy oxidization and dissolution, leading to a decrease in weight loss. Fig.…”

Section: Pickling In Phosphoric Acid Solution (Methods I)-mentioning

confidence: 99%

“…2d) with chemical composition of Mg 3 (PO 4 ) 2 , AlPO 4 , Zn 3 (PO 4 ) 2 and trace amounts of hydroxides. 22,35,[39][40][41][42] In most instances, these incompact corrosion products would deposit on the surface of Mg alloy substrate and cannot be rinsed away completely with running water. These residual corrosion products (often called "sealing smut" in anodic oxidation) remained eventually, leading to an inclusion layer between the coating and substrate, and a detrimental effect on the adhesion of the deposit.…”

Section: Pickling In Phosphoric Acid Solution (Methods I)-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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“…Wang et al and Yang et al proposed the H 2 SO 4 ‐MnO 2 etching treatment as a replacement for conventional chromic acid etching solutions improved the surface roughness and surface hydrophilicity of ABS substrates significantly . Pickling solution of H 3 PO 4 + Na 2 MoO 4 and NH 4 HF 2 activation solution could also be applied to the chemical Ni‐P coating with excellent adhesion and corrosion resistance . Another environmentally friendly process is directly depositing copper on PPy/ABS and electrodepositing nickel as a top coating.…”

Section: Introductionmentioning

confidence: 99%

KMnO₄‐system etching process and electroless nickel plating on ABS

Chen

Zhu

Zhao

et al. 2018

Materials & Corrosion

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Etching treatment for acrylonitrile butadiene styrene (ABS) resin and electroless nickel plating process have been studied. The ABS first was etched in a chromium‐free potassium permanganate etching system with different etching times. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT‐IR), and hydrophilicity test showed that the ABS is of moderate and homogeneous hole size after being etched at a temperature of 65 °C with 6 g L−1 potassium permanganate for 20 min. Then electroless nickel process was performed by immersing the ABS into in a Ni plating bath at 45 °C for 20 min at a pH of 8.5–9.5. The coating was even, dense, and reveals good corrosion resistance. In addition, the nickel plating adhesion strength reached 2.73 MPa. Therefore, the excellent performance of the KMnO4‐H2SO4‐H3PO4‐H2O etching system may replace the traditional chromic anhydride‐sulfuric acid etching system as an environmentally friendly process.

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A study of chromium-free pickling process before electroless Ni–P plating on magnesium alloys

Cited by 32 publications

References 24 publications

Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

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

KMnO₄‐system etching process and electroless nickel plating on ABS

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A study of chromium-free pickling process before electroless Ni–P plating on magnesium alloys

Cited by 32 publications

References 24 publications

Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

Corrosion protection of AM60B magnesium alloy by application of electroless nickel coating via a new chrome-free pretreatment

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

KMnO4‐system etching process and electroless nickel plating on ABS

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KMnO₄‐system etching process and electroless nickel plating on ABS