Acidic Electroless Research Articles

α-Fe2O3/Fe3O4@GO nanosheets boost the functionality of Ni[sbnd]P thin film deposited by electroless method

The highly active heterogeneous iron oxide@graphene oxide (α-Fe2O3/Fe3O4@GO) composite was produced using a simple assembly method to incorporate into the electroless NiP thin film to enhance its performance. It was thoroughly characterized using X-ray diffraction (XRD), Raman Spectroscopy, Fourier transformed infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and N2 adsorption-desorption tests. The outcomes showed that the α-Fe2O3/Fe3O4 nanoparticles were uniformly and densely distributed on the GO sheets, with a tiny diameter of about 160 nm.Ni-P/α-Fe2O3/Fe3O4@GO composite coatings were created on low-carbon steel using an acidic electroless plating bath containing various α-Fe2O3/Fe3O4@GO nanosheets. The protective effect of co-deposited nanosheets on the corrosion behavior of the coatings was examined in a 3.5 % NaCl solution. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization investigations, were used to evaluate the layers' corrosion resistance. The outcomes demonstrate that adding α-Fe2O3/Fe3O4@GO significantly increases the coatings' ability to resist corrosion. Maximum corrosion resistance was achieved at a dosage of 50 mgl−1 α-Fe2O3/Fe3O4@GO nanosheets in the plating bath. According to the SEM images the α-Fe2O3/Fe3O4@GO were implanted in the NiP matrix and were evenly disseminated over the coated surface. Moreover, the incorporation of α-Fe2O3/Fe3O4@GO enhances the mechanical properties of NiP thin film.Because of its improved performance, ease of synthesis, and low cost, this coating layer warrants more consideration as a good option for possible application to safeguard carbon steel utilized in the atmosphere.

Corrosion Resistance of Electroless Ni-P-W/ZrO<sub>2</sub> Nanocomposite Coatings in Peracid Solutions

In current investigation, the Ni-P-W/ZrO2 electroless nanocomposite coatings are deposited upon mild steel substrate (AISI 1040 grade). The W/ZrO2 nanoparticles (50 to 130 nm range) were incorporated separately into acidic electroless Ni-P matrix as a second phase materials. The as-plated EL Ni-P-W/ZrO2 depositions were also heated at 400 οC in Argon atmosphere for one hour duration and analyzed by SEM/EDAX and XRD physical methods. The Ni-P-W/ZrO2 as-plated coupons revealed nebulous type structures while heated coupons showed crystalline structures in both cases. Furthermore Ni-P-ZrO2 coatings have very less cracks and gaps as compared to Ni-P-W coatings. The corrosion tests result in peracid (0.30 ± 0.02 % active oxygen) solutions point up that corrosivity of peracid ( 500 ppm Cl) is more than peracid (0 ppm Cl) and corrosion resistance of tested coupons varies as Ni-P-ZrO2 (as-plated) > Ni-P-ZrO2 (heated) > Ni-P-W (as-plated) > Ni-P-W (heated) > MS. The utilization of Ni-P-ZrO2 nanocomposite coatings in peracid solutions can be considered a cost effective option on the basis of its better cost/strength ratio in addition to its fair corrosion resistance.

Comparison between acidic electroless deposited Cu, Ni coating and a physical vapor deposited (PVD) Al coating on an acrylonitrile– butadiene–styrene (ABS) substrate

Abstract The coating is used to provide protection or functional properties to the surfaces of the substrate. In this study, acrylonitrile–butadiene–styrene plastic was coated with copper/ nickel by using an acidic electrolysis deposition method and with aluminum using the physical vapor deposition method. It has been investigated to find out which of these coating methods can be used as an outdoor lighting reflector. Therefore, these two coating methods were compared using sodium carbonate test, scratch test, surface roughness and reflection efficiency tests. In addition, copper/nickel deposited and aluminum deposited on acrylonitrile– butadiene–styrene plastic surfaces were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry. The surface roughness and reflection efficiency of acrylonitrile–butadiene– styrene plastic coated with aluminum applying the plasma vapor deposition method was more efficient than copper/ nickel coated acrylonitrile–butadiene–styrene obtained by applying a non-electric bath method. It has been determined that the samples with electroless copper/nickel coating have a better outdoor resistance than the aluminum coated samples. On the other hand, it was also determined that the surface roughness and reflection efficiency of the aluminum coated samples was better with the plasma vapor deposition method than that of the electroless copper and nickel coated samples. The results show that aluminum coating with the physical vapor deposition method on acrylonitrile–butadiene–styrene plastic is more suitable for reflector technology in terms of light efficiency.

A Facile Method Combined with Acetic Acid Modification and Electroless Plating to Fabricate Copper-plated Nylon 12 Powder for Antistatic Coating

Metal particle could deposited on Nylon 12 (PA12) surface using electroless plating with excellent interface and distribution, but the use of noble metal as catalytic site would increase the process cost and restrict its application. In this work, we employed a facile technology combined with acetic acid etching and electroless copper plating to prepare Cu/PA12 composite powder, and it used as conductive filler for antistatic coating was also studied. Results manifested defects (hole and amorphous structure) and amide group established on etched PA12 surface, which would facilitate the destruction of the [Cu-EDTA] structure, and then the reduction of REDOX barrier. As a result, Cu and Cu2O particles deposited on its surface. The downward trend of volume resistivity of antistatic coating appeared the rule of slow-fast-slow. The lowest volume resistivity was about 105 ohm�cm. This means that the dependable technology has great potential application in preparing metal/polymer composite material at a low cost.

A low temperature electroless nickel plating chemistry

An acidic electroless nickel bath was formulated to plate high phosphorus nickel alloy at a low temperature from 45 to 50 °C. The low temperature EN bath, containing nickel ions, reducing agent, complexing agent, stabilizer, and accelerator, was optimized in composition to deposit high phosphorus nickel alloy (>11 wt% P) at temperature <50 °C which is not achievable by either commercial alkaline EN baths or commercial acidic EN baths at such a low plating temperature. The successful electroless forming of an EN film micro sieve based on positive photoresist patterns demonstrated that the low temperature bath is suitable for high phosphorus EN plating with temperature sensitive polymer materials.

Corrosion Study of Electroless Ni-P-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;- ZrO&lt;sub&gt;2&lt;/sub&gt; Nanocomposite Coatings in Paper Mill Digester

Objectives: To acquire more production and better quality of paper. The pulp and paper mill digesters are currently operated at increased temperature and sulfidity which results from increase in uniform and localized type of corrosion attacks on digester materials. Methods/Statistical Analysis: The current study intends to search corrosion protection mechanism in non-conventional (inclusion of 2.5gpl of each synthesized Al 2 O 2 and ZrO 2 nanoparticles into acidic EL Ni-P matrix, 2 hr constant stirring, temperature range 85 to 900C)alternate materials with liquor composition, concentration, and operating parameters. The NiPAZr(MS-Ni-P-Al 2 O 2 -ZrO 2 ) nanocomposite coatings were deposited on mild steel (MS)substrate by electroless (EL) technique. To carry out an in-plant test, the coupons of conventional material (mild steel, MS) and non-conventional materials (NiPAZr as-plated and NiPAZr heat treated at 3800C) were exposed in mid part (near strainer) of 2 nd batch digester of SPML (U.P., India) for six months duration. The exposed corroded coupons after removal from the digester were cleaned mechanically and chemically (ASTM specifications) and analyzed for uniform and pitting type corrosion attack. Findings: From corrosion point among all the coupons, it is concluded that mild steel (MS)coupon experiences the highest corrosion attack while NiPAZr (as-plated and heat treated) coated coupon slow corrosion attack. The mid part of the digester where the test rack was fitted is mainly affected due to general and pitting corrosion. Therefore, this in-plant test suggests that in applied conditions, it would be better to construct/fabricate the mid part of the digester with EL NiPAZr nano-composite (as-plated or heat treated at 3800C) coatings. These EL nano-composite coatings can be a cost effective option in contrast to conventional materials (MS, SS304L, SS316L and SS2205 etc.) for the paper industrialist to construct/fabricate especially mid part of the digester. Application/ Improvement: For making/fabrication mid part of the digesters these nano-composite coatings can be a cost effective option in comparison to conventional materials as well as can be applied up to very high-temperature range

Structure and effects of electroless Ni–Sn–P transition layer during acid electroless plating on magnesium alloys

An electroless ternary Ni–Sn–P transition layer with high corrosion resistance was applied for acid electroless nickel plating on magnesium alloys. The surface morphologies and microstructure of the traditional alkaline electroless Ni–P and novel Ni–Sn–P transition layers were compared by SEM and XRD, and the bonding strengths between the transition layers and AZ31 magnesium alloys were tested. The corrosion resistance of the samples was analyzed by porosity test, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) in acid electroless solution at pH 4.5 and immersion test in 10% HCl. The results indicate that the transition layer is essential for acid electroless plating Ni–P coatings on magnesium alloys. Under the same thin thickness (~6 μm), the electroless Ni–Sn–P transition layer possesses superior properties to the traditional Ni–P transition layer, including high amorphization, smooth and dense surface without pores, enhanced bonding strength and corrosion resistance. Most importantly, acid electroless Ni–P coatings can be successfully deposited on magnesium alloys by using Ni–Sn–P transition layer.

Effect of novel ternary ligand system on acidic electroless Ni-P plating on AZ91D magnesium alloy

The electroless Ni-P coatings on AZ91D magnesium alloy substrate were prepared using the acidic hypophosphite-reduced electroless nickel bath containing the novel ternary ligand system. The results indicate that the deposition rate varies with the ternary ligand concentration in plating solution. The structural and morphological characteristics of the coatings were analyzed by XRD and SEM. The anticorrosion properties of the Ni-P coatings were evaluated in 3.5% NaCl solution by electrochemical impedance and potentiodynamic polarization methods. The amount of ternary ligands in electroless plating bath has an significant effect on the surface morphology and structure of Ni-P coatings. The decrease of crystallization temperature and increase of crystallization heat of all the deposits with an increase in ternary ligand concentration are found by DSC measurements. The coating obtained with 0.035 mol/L ternary ligand additive in plating bath can offer a better surface homogeneity and improve corrosion resistance.

EFFECT OF SDS ON THE DISPERSION STABILITY OF YSZ PARTICLES IN AN ELECTROLESS NICKEL SOLUTION

Optimum particle dispersion is an essential feature for composite coatings carried out on the autocatalytic electroless nickel plating platform. In this regard, the potential influence of an anionic surfactant, sodium dodecyl sulphate (SDS), on the dispersion stability of a ceramic, yttria stabilized zirconia (YSZ), in an acidic electroless nickel solution of pH 4.9 has been assessed in this study. Ultra violet-visible spectrophotometry was used in accordance with the Beer-Lambert law (–log (I 1/I 0) = A) to evaluate the rate of YSZ particle sedimentation in electroless nickel solutions with and without surfactant. Measurement of the particles' zeta potential at each surfactant concentration was conducted in parallel with the UV-vis tests with the aim of establishing the interaction among the surfactant, YSZ particles, and electroless nickel solution. A slight increase in the negative magnitude of the particles' zeta potential indicated the adsorption of SDS onto the particles' surface and a possibility of contributing to its stability. However, the surfactant's inability to counteract an electroless nickel solution–induced particle accretion resulted in the observation of poor YSZ particle stabilities at all the investigated surfactant concentrations.

Electroless Multilayer Coatings Used in the Protection of Thermosyphon Economizer from Corrosion

Economizers are widely employed in the boiler system to increase efficiency and save energy. However one prominent problem is the severe corrosion of economizer due to the decrease of the exhaust temperature of boiler. Ni–P/Cu/Ni-P multilayer coatings, which could effectively improve the corrosion resistance of the facilities in economizer, are introduced in the present work. The three-layer coatings, whose composition is Ni–P/Cu/Ni-P from substrate to surface, were prepared using dual baths (acidic hypophosphite-reduced electroless nickel bath and acidic replacement electroless copper bath). The corrosion resistance of the coatings was evaluated by porosity and electrochemical tests. The results of porosity evaluation show that all the multilayer coatings performed better than the single-layer coatings of similar thickness. Similarly, The electrochemical tests showed lower corrosion current density for the multilayer coatings in 3.5 wt.% NaCl aqueous solutions.

Preparation and Corrosion Resistance of Electroless Plating of Ni-Cr-P/Ni-P Composite Coating on Sintered Nd-Fe-B Permanent Magnet

This paper introduces electroless plating Ni-Cr-P/Ni-P composite coating technologies and techniques on the Nd-Fe-B permanent magnet surface. It has got a Ni-Cr-P/Ni-P composite coating successfully on the Nd-Fe-B substrate surface through rational processing plan. The coating surfaces are bright and have low Porosity, good binding between the electroless plating and Nd-Fe-B matrix. The experimental results show that the composite coating prepared by Ni-Cr-P electroless plating (15min) and Ni-P acidic electroless plating (45min) has amorphous structure, simple process and better anticorrosion property in both alkaline and acidic medium.

Optimizing of Pretreatment Process of Electroless Ni-P Plating on Aluminum Substrate

In order to improve and simplify the process of electroless Ni-P plating on aluminum substrate, a activated solution and process were optimized by orthogonal test, the plating morphology were analysed using Quanta 200 type scanning electron microscope. The bond between the plating and aluminum substrate were evaluated using method of water quenching and alternating bending test. The results show that good coating can be obtained on aluminum substrate under the normal condition of the acid electroless Ni-P plating solution with sulfuric acid of 120g/L and nitric acid of 10-15g/L as activated solution and activated time of 20 min. And the good bond between the plating and aluminum substrate was obtained.

Optimizing of Pretreatment Process of Electroless Ni-P Plating on AZ91D Substrate

In order to improve and simplify the process of electroless Ni-P plating on AZ91D magnesium alloy substrate, pretreatment process and deposite time were optimized by orthogonal test, the plating morphology were analysed using Quanta 200 type scanning electron microscope. The bond between the plating and aluminum substrate were evaluated using method of water quenching and alternating bending test. The results show that good coating can be obtained on AZ91D substrate under the condition of the acid electroless Ni-P plating solution with pickling time of 40-50s, activated time of 10 min. And the good bond between the coating and AZ91D substrate was obtained.

A Novel Electroless Ni-P Deposition on AZ91D Magnesium Alloy

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.

Effects of complexing agents on acidic electroless nickel deposition

Our previous study reported the influences of different complexing agents on electroless nickel (EN) by examining the properties of the deposits. In the present work, the effects of four common-used complexing agents on EN deposition rate and the stability of solution pH values were examined, either with an acetic pH buffer agent or absent of them. It is indicated that the pH buffering effect of them is dominative when the EN solution is lack of the pH buffer. Under this situation, the EN deposition rate increases with the concentration of complexing agents increasing. The EN deposition rate decreases with further adding the complexing agent when the solution already has enough pH buffer capability. Electrochemical impedance spectroscopy obtained during EN deposition illustrates that, in this case, the enhanced reaction resistance is the main reason for a lower deposition rate. However, the influence of polarization caused by mass transfer is not negligible at high complex ratio for sodium citrate and malic acid EN solutions.

Effect of 3-S isothiuronium propyl sulfonate on electroless nickel deposition

The effects of organic additive, 3-S isothiuronium propyl sulfonate (UPS) on bath stability, deposition rate, reaction activation energy, and Ni-P coating composition in acidic electroless nickel (EN) plating were investigated. The study was performed by measuring the polarization curves and X-ray fluorescence spectrometer (XRF) in combination with X-ray photoelectron spectroscopy (XPS) analysis. The results show that UPS improves bath stability and increases the reaction activation energy. At lower concentration, UPS is an effective accelerator for EN deposition; whereas, at higher concentration, it decreases deposition rate. It also reveals that UPS inhibits the anodic oxidation of hypophosphite and accelerates the cathodic reduction. In addition, UPS decreases the phosphorus content in Ni-P deposit and can be adsorbed on the deposit surface and compound with Ni2+. On the basis of these results, the effect mechanism of UPS on electroless nickel deposition was deduced.

Acidic electroless copper deposition on aluminum-seeded ABS plastics

Copper (Cu) was successfully deposited onto aluminum (Al)-seeded acrylonitrile–butadiene–styrene (ABS) plastics in acidic electroless baths containing 15 wt.% copper sulfate and 5 wt.% of any of the acids including sulfuric acid (H 2SO 4), phosphoric acid (H 3PO 4), nitric acid (HNO 3), or acetic acid (CH 3COOH). Cu crystals were formed on the Al-seeded ABS surfaces deposited from all of the four acidic baths. Electroless Cu deposition was carried out at both room temperature and 60 °C, and the deposition rate was dramatically increased at the elevated temperature. Conductive Cu layers were developed on ABS surfaces only from the H 2SO 4, H 3PO 4, and CH 3COOH baths but were not from the HNO 3 one, and the possible reason of failure of the HNO 3 bath is discussed. The electrolessly Cu deposited ABS surfaces were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The adhesion of conductive Cu layers to the ABS substrates was assessed and showed excellent strength. The acidic baths developed in this study may provide more alternative options for plating on plastics (POP) via the acidic electroless Cu deposition route.

Electroless Sn–Ni alloy plating with high Sn content free of activation pretreatment

Electroless plating technique was used to coat Sn–Ni alloy on copper substrate with high Sn content by adding the amounts of thiourea as special complexing agent and sodium hypophosphite as reducing agent to an acidic electroless plating bath of SnCl 2 and NiCl 2, which avoided activation pretreatment in plating process. The Sn content of the Sn–Ni layer increased with lowing temperature which reached 60 wt.% under optimum plating conditions. The effect of thiourea and sodium hypophosphite amount, plating temperature, and the acidity of plating bath was also discussed in this article. The corrosion-resistance properties of Sn–Ni alloy layer proved to be good by testing the anodic polarization curves of the alloy layer.

Amorphous Ni–Mo–P diffusion barrier deposited by non-isothermal deposition

Ni–Mo–P barrier layers deposited on silicon wafers without Pd activation pretreatment were prepared using the non-isothermal deposition (NITD) method in an acidic electroless bath. The operating conditions for fabricating the Ni–Mo–P barrier layers were presented, and the effect of the pH values on the film composition, electric resistivity and thermal stability have been investigated. The thicknesses of Ni–Mo–P films are around 15–20 nm in acidic bath. Our results indicate increasing amounts of Mo and decreasing amounts of P with increasing pH. The electric resistivity decreased with increasing pH value due to the increase of the Mo content in the Ni–Mo–P film. The amorphous structure was formed at pH 3 and 4, but a quasi-amorphous structure was formed at pH 5. Based on our experimental results, the thermal stability of Ni–Mo–P film prepared at pH 4 remains stable up to 650 °C for 1 h annealing.

Friction and wear behavior of electroless Ni–P and Ni–W–P alloy coatings

Electroless nickel (EN) plating has received attention as a hard coating for industrial applications due to its high hardness, uniform thickness as well as excellent corrosion and wear resistance. The electroless Ni–P deposit is a supersaturated alloy in as-deposited state, and can be strengthened by precipitation of nickel phosphide crystallites with suitable heat treatments. However, the hardness of Ni–P films degrades with excessive annealing due to grain coarsening. An alternative to Ni–P coatings is the ternary alloy coating with the addition of a third element to the binary Ni–P system. The ternary Ni–M–P alloy, where M is typically a transition metal such as W, Co, Mn, Re and Mo has superior properties compared to the binary Ni–P alloy, and therefore, could extend its range of applications. The present paper discusses the synthesis and tribological behavior of Ni–P and Ni–W–P deposits. Deposition is done from an acidic electroless bath. Deposits with varying tungsten content were synthesized. Chemical analysis shows that tungsten incorporation reduces the phosphorus content in the deposit. Phosphorus content varied from 5 to 12 wt.% depending upon the tungsten incorporation in the deposit which in turn varied between 2 and 14 wt.%. Coatings with high tungsten content exhibit very good wear resistance compared to binary Ni–P as well as low tungsten ternary alloy deposits.