Papers by Keyword: Electroless Nickel Plating

Abstract: Electroless nickel (Ni) and composite nickel coatings (Ni+TiN) are investigated in this study. EFFTOM -Nickel Method for electroless nickel plating is applied. Nanosized TiN particles (50nm) are used as a strengthening material. The coatings are plated on ductile cast iron samples. The wear tests of the coatings by the classic model TABER ABRASER “disc to disc” are carried out. The observation of the samples microstructure by means of an optical metallographic microscope GX41 OLIMPUS and the microhardness measurements by Knoop Method are performed. The wear resistance, the thickness and microhardness of the samples before and after thermal processing at 290°C, 6 h are defined.

Abstract: Acid Ni-P and alkaline Ni-P coatings were prepared on 30CrMnSi alloy steel by electroless plating method. 3 pH values were selected for each type. The phosphorus content, hardness and wear resistance coefficient of the 6 kinds of coatings were tested. Experimental results showed that the mass fraction of P was less than 4% range, with the increase of P content, the hardness and wear resistance of two kinds of coating had been improved, the hardness and wear resistance of acid coating were better than that of alkali coating.

Abstract: Aluminium alloy is difficult to be plated because of high chemical activity. In order to obtain electroless nickel plating with excellent adhesion to the substrate, the key lines is the pretreatment process. This study introduces several significant pretreatment processes of aluminium alloy surface at home and abroad for these years, and describes the principles of pretreatment processes. Finally, the development direction of pretreatment processes for aluminium alloy is forecasted.

Abstract: The metallization of polymer microsphere has attracted attention in recent years due to its wide range of technological applications. In this study, chemical etching with concentrated sulfuric acid and potassium dichromate bichrome (K₂Cr₂O₇) was used to prepare acrylic resin microspheres’ surfaces for high polymer/metal adhesion. Meanwhile, the influence of etching time and temperature on the surface morphology of electroless nickel plated acrylic resin microsphere was investigated. The optimal etching process conditions were identified in this test as follows: etching temperature of 70°C and etching time of 60 ~ 90min. Specular reflection FTIR and scanning electron microscopy was employed to observe the morphology of the nickel plated films and the Ni/polymer interfacial structures. As the results shown, the effect of etching process conditions on the coating thickness and the surface topography of the film was obviously.

Abstract: A pre-cleaning and an electroless nickel plating (EN-HP) were applied to copper foil to improve its tribological behaviour and corrosion resistance. The coating porosity was measured by the corrodkote, tribological behaviour was measured with microhardness tester and a CSM ball-on-disk tribometer, corrosion resistance was measured by potentiodynamic polarization in 3.5 wt.% NaCl solution. Matte nickel plating (mNi) and moderate compact Ni–P coating (EN-MP) were made as comparisons to EN-HP in those tests. By deposition of EN-HP, both coating porosity and tribological behaviour are greatly improved compared to mNi, and the corrosion resistance is distinctly ameliorated to the comparisons. Above research demonstrates that the copper foil with EN-HP coating is good underlay in assemblage of machine.

Abstract: The study presents the effect of heat treatment on electroless N-P-C_g-SiC composite coated cast AlSi (ADC12) alloy. No significant changes are noted on the average surface roughness and surface morphology of the coating film with different heat treatment processes. The growth of the hard Ni₃P phase in the electroless Ni-P-C_g-SiC composite coating after heat treatment at 400°C for one hour strongly enhance the micro hardness of the AlSi-alloy (ADC12) surface from originally 101HV to 689HV. However, the micro hardness of the cast AlSi-alloy substrate decreases form 100HV to 60HV.

Abstract: The study presents the electroless N-P-C_g-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 C_g particles are homogenously distributed.

Abstract: Coating of ME20M magnesium alloys was first carried out using electroless nickel plating technique with an environmentally-friendly pretreatment. The morphology and specific weight loss of the pickling process were investigated. The Ni-P coating was characterized by its structure, morphology, chemical composition, adhesion strength and corrosion resistance. The SEM image shows that the pyrophosphate pickling process can produce a rough surface and the thermal shock test indicates excellent adhesion strength between magnesium alloys and Ni-P coating. The damp heat test and electrochemical measurement prove the Ni-P coating significantly increase the corrosion resistance of ME20M magnesium alloys.

Abstract: t is that Ni/C composite powder are prepared by electroless plating with hydrazine hydrate as a reducing agent and compound complex agent.To investigate the effect of main salts, reductant dosage, graphite dose and compound complex agent ratio on the conductivity of composite powder.It is can be obtained under optimum conditions with good electrical properties , the rough surface is completely coated Ni / C composite powder.

Abstract: Small batches of two oxide powders falling in the particle size range of about 30-230 μm were received from industrial sources and were electroless nickel (EN) coated in order to prepare properly modified reinforcing particles for further laboratory experiments with the Laser Melt Injection (LMI) technique to produce particle reinforced steel composite surface layers. The partially calcined alumina (Al2O3) as well as the hydrothermally recycled crystalline iron(III) oxide precipitate were characterized first to check their exact size ranges, specific surface areas and major chemical contaminants so that the best possible EN plating technique would be selected and applied. It was revealed soon that the sensitization and activation pre-treatment steps could not be omitted and after their proper adjustment, also the composition and pH of a relatively commonly used hypophosphite reducing type bath had to be modified to the given purpose. Eventually a slightly alkaline EN bath was successfully prepared with which both industrial oxide powders surface could be nickel coated soundly, which final result was demonstrated also by several metallographic testing techniques showing the microstructure of the quite evenly and fully coated oxide particles.