scholarly journals Development of Electroless Ni Plating Bath Using Ti (III) Ion Reductant.

2002 ◽  
Vol 53 (10) ◽  
pp. 694-697 ◽  
Author(s):  
Shinji INAZAWA ◽  
Masatoshi MAJIMA ◽  
Keiji KOYAMA ◽  
Yoshie TANI ◽  
Shigeyoshi NAKAYAMA ◽  
...  
Keyword(s):  
Plating Bath ◽  
Electroless Ni

A New Pre-Treatment with Phosphoric Acid and Hydrofluoric Acid of Electroless Ni-P Plating on Mg Alloy

2015 ◽  
Vol 729 ◽  
pp. 21-26
Author(s):  
Zhi Hui Xie ◽  
Jun Li Zhou ◽  
Shu Rong Xiang ◽  
Fang Chen
Keyword(s):  
Corrosion Current ◽  
Treatment Method ◽  
Mg Alloy ◽  
Cross Sectional ◽  
Plating Bath ◽  
Pickling Solution ◽  
Before And After ◽  
The Matrix ◽  
Pre Treatment ◽  
Electroless Ni

In order to develop a chromium-free pre-treatment method for electroless Ni-P (ENP) plating on magnesium alloy from an acidic plating bath, several various pickling and activation processes were studied in the present work. The surface morphologies of the matrix before and after etching or activation as well as the surface and cross sectional appearance of the Ni-P coatings were observed by scanning electronic microscope (SEM), while the elemental compositions were detected by energy dispersive X-ray spectroscopy (EDS). Those surface characterizations along with the scribe and grid testing results showed that the coatings obtained from etching only in H3PO4 solution display poor adhesion due to the existance of an interlayer between the matrix and the coatings. When fluoride was added into the pickling solution, the adhesion of the Ni-P coatings was also unsatisfactory because of the bad mechanical interlocking. By comparison, the Ni-P coatings obtained from pickling in 400 cm3·dm−3 H3PO4 solution followed by 10 cm3·dm−3 HF activation exhibit good characteristics in both adhesion and anti corrosion. The polarization test in 3.5wt.% NaCl aqueous solution showed that the corrosion potential (Ecorr) and corrosion current density (Icorr) of the new achieved coatings increases positively from −1.65 V to −0.87 V and decreases remarkably from 2.09 mA⋅cm−2 to 3.58 μA⋅cm−2, respectively (both compared with the bare Mg alloy).

Improvement on Hardness of 6061 Al Alloy Using an Electroless Ni-P Coating

2010 ◽  
Vol 26-28 ◽  
pp. 293-296 ◽  
Author(s):  
Wen Feng Qin ◽  
Jiang Long ◽  
Feng Liu
Keyword(s):  
Surface Morphology ◽  
Sodium Hypophosphite ◽  
Al Alloy ◽  
Plating Bath ◽  
Nodular Structure ◽  
P Content ◽  
Scanning Electron Microcopy ◽  
Alloy Plating ◽  
6061 Al Alloy ◽  
Electroless Ni

The surface morphology and hardness of electroless Ni–P alloy plating on 6061 aluminum alloys substrate in an alkaline plating bath with sodium hypophosphite as reducing agent were investigated. The effects of bath pH on the plating rate, compositions and surface morphology of theelectroless Ni-P deposits were studied. The results showed the deposition rate of the electroless Ni–P deposits increased with the rise of the bath pH, while the P content decreased. Scanning electron microcopy (SEM) of the deposits showed nodular structure for the deposits. Hardness data of the Ni-P coatings indicated that electroless Ni–P plating could obviously improve the hardness of 6061aluminum alloy.

Formation and Structural Characterization of Electroless Ni-B-P Ternary Alloy Coatings

2014 ◽  
Vol 592-594 ◽  
pp. 385-390 ◽  
Author(s):  
P.G. Venkatakrishnan ◽  
S.S. Mohamed Nazirudeen ◽  
T.S.N. Sankara Narayanan
Keyword(s):  
Electroless Plating ◽  
Morphological Characteristics ◽  
Reducing Agents ◽  
Sodium Hypophosphite ◽  
Electron Microscopic ◽  
Plating Bath ◽  
Peak Broadening ◽  
Chloride Hexahydrate ◽  
Electroless Ni

The aim of the present investigation is to study the formation of electroless Ni-B-P alloy coatings and structural and morphological characterization of various coatings with different boron and phosphorous content. An alkaline plating bath with nickel chloride hexahydrate as the source of nickel ions and sodium borohydride and sodium hypophosphite as reducing agents were used for the formation of electroless Ni-B-P alloy coatings. The influence of changes in the concentrations of the reducing agents in the electroless plating bath on the chemical composition, structural and morphological characteristics of the coatings were studied. Scanning electron microscopic studies revealed that the surface morphology of Ni-B-P alloy coatings changed from corn cob-like structure to cauliflower-like structure with increasing borohydride concentration in electroless plating bath, whereas increase in hypophosphite concentration favoured sideway growth, thereby decreased the surface roughness of the Ni-B-P alloy coatings. The peak broadening in the X-Ray Diffraction profiles indicates the large reduction in the crystallite size of the electroless Ni-B-P alloy coatings with increasing boron content in the coating (i.e. for higher borohydride concentration in the plating bath).

scholarly journals Corrosion Resistance of Electroless Ni-Cu-P Ternary Alloy Coatings in Acidic and Neutral Corrosive Mediums

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Mbouillé Cissé ◽  
Mohamed Abouchane ◽  
Tayeb Anik ◽  
Karima Himm ◽  
Rida Allah Belakhmima ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Corrosion Mechanism ◽  
X Ray Diffraction ◽  
Plating Bath ◽  
Edx Analysis ◽  
Tafel Polarization ◽  
Marginal Improvement ◽  
Electroless Ni

Electroless Ni-Cu-P alloy coatings were deposited on the ordinary steel substrate in an acidic hypophosphite-type plating bath. These coatings were characterized by a scanning electron microscope (SEM) and an X-ray diffraction. The micrograph shows that coating presents a nodular aspect and is relatively homogeneous and very smooth. The EDX analysis shows that the coating contains 12 wt.% of phosphorus element with a predominance of nickel element. In addition, the anticorrosion properties of the Ni-Cu-P coatings in 1 M HCl, 1 M H2SO4, and 3% NaCl solutions were investigated using Tafel polarization curves, electrochemical impedance spectroscopy, and SEM/EDX analysis. The result showed a marginal improvement in corrosion resistance in 3% NaCl solution compared to acidic medium. It also showed that the corrosion mechanism depends on the nature of the solution.

A Novel Electroless Ni-P Deposition on AZ91D Magnesium Alloy

2010 ◽  
Vol 154-155 ◽  
pp. 1330-1335
Author(s):  
Li Ping Wu ◽  
Zhong Dong Yang ◽  
Jing Jing Zhao ◽  
Yong Ping Xie
Keyword(s):  
Magnesium Alloy ◽  
Electrochemical Impedance ◽  
Electroless Nickel ◽  
Deposition Process ◽  
Chemical Compositions ◽  
Good Adhesion ◽  
Plating Bath ◽  
Az91d Magnesium Alloy ◽  
Structure Morphology ◽  
Electroless Ni

Currently, most of electroless nickel phosphorus plating on magnesium alloys has following disadvantages. First, it has been suffering from corrosion issues caused by acidic electroless bath. Second, in order to increase the strength of Ni-P coatings to the Mg substrate, the pretreatments for electroless Ni-P employ hydrofluoric acid (HF) and hexavalent chromium (Cr6+) which can cause pollution and health problems . In this paper, we developed HF-free and alkaline electroless Ni-P deposition process on AZ91D magnesium alloy which avoids the use of SO42- and Cl- ions in the electroless plating bath, thus leading to good adhesion and corrosion resistance of electroless Ni-P coating on magnesium alloy. XRD, SEM, EDS techniques were used to study the structure, morphology, and chemical compositions of the conversion coating and Ni-P coating, respectively. Polarization measurements indicated that the corrosion rate of Ni-P coated Mg was six times lower than that of bare Mg. Electrochemical impedance spectroscopy (EIS) also showed that the Ni-P coating could effectively protect Mg alloy from corrosion.

Electroless Ni-P-Cg(Graphite)-SiC Composite Coating on Cast AlSi Alloy

2013 ◽  
Vol 795 ◽  
pp. 540-544
Author(s):  
M.M. Mohtar ◽  
Z.M. Ripin ◽  
Z.A. Ahmad
Keyword(s):  
Film Thickness ◽  
Composite Coating ◽  
Substrate Surface ◽  
Bath Temperature ◽  
Coating Film ◽  
Chemical Concentration ◽  
Plating Bath ◽  
Alsi Alloy ◽  
Ph Level ◽  
Electroless Ni

The study presents the electroless N-P-Cg-SiC composite coating on cast AlSi (ADC12) alloy where the bath temperature is maintained at 90°C, pH level is controlled between 4.5 to 5.0 and stirred at 450 rpm with mechanical stirrer to avoid particles sedimentation. The increase of the coating film thickness is very insignificant after one hour of coating duration. This outcome is supposed to be due to inconsistent chemical concentration in the plating bath after this period. The nominal coating thickness of 39 μm is achieved after the substrate is immersed for 1 hour in four consecutive plating baths, respectively. The coating film is also successfully adhered to the substrate surface with the SiC and Cgparticles are homogenously distributed.

Fabrications of Electroless Ni-P Composite Coatings before and after Annealing and Tribological Analyses

2015 ◽  
Vol 642 ◽  
pp. 286-291
Author(s):  
Chang Shuo Chang ◽  
Kung Hsu Hou ◽  
Ming Der Ger ◽  
Chen Kuei Chung ◽  
Jen Fin Lin
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Wear Resistance ◽  
Crystalline Phase ◽  
Composite Coatings ◽  
Plating Bath ◽  
Sic Particles ◽  
Before And After ◽  
Mechanical Performances ◽  
Electroless Ni

In the present study, SiC reinforced particles were introduced to the Ni-P plating bath, and developed high SiC content composite coatings. Thin films nature properties and mechanical performances were evaluated well. The results showed that the Ni-P alloy embedded SiC particles formed a few cavities, and reduced coatings hardness and wear resistance in as-plated condition. After 400°C heat-treatment, Ni3P crystalline phase formed and reached the max hardness, and conducted excellent trybological performances. SiC particles were decoposited in 600°C and reacted with Ni to form Ni3Si and Ni5Si2, caused the decreasing in hardness.

THE CORROSION BEHAVIOR OF ELECTROLESS Ni-P-SiC NANO-COMPOSITE COATING

2008 ◽  
Vol 22 (18n19) ◽  
pp. 3031-3036 ◽  
Author(s):  
FARYAD BIGDELI ◽  
SAEED REZA ALLAHKARAM
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Electroless Nickel ◽  
Energy Dispersive Spectrum ◽  
X Ray Diffraction ◽  
Plating Bath ◽  
New Class ◽  
Nano Composite Coating ◽  
Electroless Ni

Composite coatings constitute a new class of materials which are mostly used for mechanical and tribological applications. The corrosion resistance of these composite coatings, however, has not been systematically studied and compared. In this study, electroless Ni – P composite coatings are formed on St 37 steel through the addition of nano-scale SiC particles to the plating bath. This work aimed to investigate the corrosion characteristics of electroless nickel composite coatings using electrochemical measurements which include polarization and electrochemical impedance spectroscopy tests. The morphology and structure of the composite coatings were studied by scanning electron microscopy (SEM), energy dispersive spectrum (EDS) and X-ray diffraction (XRD). The results showed that both electroless nickel and electroless nickel composite coatings demonstrated significant improvement of corrosion resistance in salty atmosphere.

scholarly journals A New Route for Direct Electroless Ni-P Plating on Magnesium Alloys

2017 ◽  
Vol 33 (2) ◽  
Author(s):  
Bùi Xuân Vương
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloys ◽  
Substrate Surface ◽  
Nickel Sulfate ◽  
Plating Bath ◽  
High Adhesion ◽  
Pickling Solution ◽  
Salt Component ◽  
Coarse Surface ◽  
Electroless Ni

This report describes a new route for direct electroless Ni-P plating on magnesium alloys using nickel sulfate as the main salt component. The surface morphology, chemical composition and corrosion resistance of coatings were determined using SEM, EDX and electrochemical polarization techniques. Ni-P coatings with good corrosion resistance and high adhesion were obtained using this route and improved pretreatments. A mixture of H3PO4 and HNO3 was used as a pickling solution for Mg substrate pretreatment. A coarse surface was produced via the developed pickling procedure. A mechanical occlusive force is believed to exist between the coatings and the substrates. Twice activations, K4P2O7 and NH4HF2 as activation components, respectively, were applied for the pretreatment of magnesium alloy plating. An optimal F/O ratio on the Mg substrate surface was obtained by this pretreatment method. The activation film has insoluble partial fluorides which can depress the active points on substrate surface against the reaction of Mg with Ni2+ and H+ in the plating bath. A highly stable bath with pH 5 buffer was identified. The advantages of the developed process include chromium-free, low fluoride, and high bath stability. It is applicable for the production of motorcycle part plating.  

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