Initial Deposition of Electroless Nickel from Borohydride-Reduced Bath on Various Ferrous Alloys (original) (raw)
Related papers
Applied Surface Science, 2012
Quality and homogeneity of electroless nickel-boron coatings are very important for applications in corrosion and electronics and are completely dependent on the formation of the deposit. The growth and formation process of electroless nickel-boron was investigated by immersing mild steel (St-37) samples in an un-replenished bath for various periods of time (from 5 s to 1 h). The coatings obtained at the different stages of the process were then characterized: thickness was measured by SEM, morphology was observed, weight gain was recorded and top composition of the coatings was obtained from XPS. Three main phases were identified during the coating formation and links between plating time, instantaneous deposition rate, chemistry of last formed deposit and morphology were established. The mechanism for initial deposition on steel substrate for borohydride-reduced electroless nickel bath was also observed. Those results were confronted with chemistry evolution in the unreplenished plating bath during the process. This allowed getting insight about phenomena occurring in the plating bath and their influence on coating formation.
Formation and characterization of borohydride reduced electroless nickel deposits
Journal of Alloys and Compounds, 2004
Abstract The present work aims to study the formation of electroless Ni-B deposits and evaluation of their characteristic properties. An alkaline bath having nickel chloride as the source of nickel and borohydride as the reducing agent was used to prepare the electroless Ni-B deposits. The influence of variation in bath constituents as well as operating conditions on the plating rate, and, the nickel and boron content, of the resultant Ni-B deposits were studied. Selected deposits were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), evolved gas analysis (EGA), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM), respectively, for assessing the phase content, phase transformation behaviour, liberation of hydrogen during crystallization, saturation magnetic moment and micro-structural features. The corrosion resistance of Ni-B deposits, in 3.5% sodium chloride solution, both in as-plated and heat-treated (450 °C/1 h) conditions, was also evaluated by potentiostatic polarization and electrochemical impedance studies. XRD patterns reveal that Ni-B deposits of the present study are amorphous in as-plated condition and undergo phase transformation to crystalline nickel and nickel borides upon heat-treatment. DSC traces exhibit two exothermic peaks at 306 and 427 °C, corresponding to the phase transformation of amorphous Ni-B to crystalline nickel and Ni3B phases and the transformation of a higher phase compound to Ni3B and Ni2B, respectively. TEM microstructures and EGA strongly support the occurrence of phase transitions at 306 and 427 °C. Electroless Ni-B deposits demonstrate a moderate corrosion resistance in 3.5% sodium chloride solution. The extent of corrosion resistance offered by electroless Ni-B deposits is relatively less compared to electroless Ni-9 wt.% P deposit. Keywords Transition metal alloys; Amorphous materials; Electrochemical reactions; Thermal analysis; TEM --------------------------------------------------------------------------------
Industrial & Engineering Chemistry Research, 2012
Electroless nickel−boron samples with 5 wt % boron were synthesized on mild steel with a bath based on sodium borohydride. Evolution of chemistry in the bath was followed during plating. Most reactive was consumed during the first half hour of the process. However, reducing agent and stabilizer concentration evolve differently: the use of sodium borohydride is limited by diffusion toward the surface, while adsorption on the surface of the sample is the rate-limiting step for lead tungstate. A direct link was established between the amount of stabilizer used and the surface of the sample; however, it cannot be applied to the use of sodium borohydride. A batch replenishment procedure for the electroless bath was developed by chemistry analysis at different stages of the plating process. This procedure allowed bath reuse and reduction of the number of new bath preparations.
Materials Science and Engineering: B, 2010
The initial deposition and growth of electroless nickel-boron deposits on mild steel was studied: 15 the films were prepared in an electroless plating bath using sodium borohydride as reducing 16 agent. Samples were immersed in the plating solution for times from 5 s to 1 h and the 17 morphological evolution of the deposit was followed by scanning electron microscopy (SEM) 18 observation of the surface and prepared cross sections. Energy dispersive X-ray spectrometry 19 (EDX) and glow discharge optical electro spectroscopy (GDOES) analysis were used to obtain 20 information about the chemistry of the deposits and their results were correlated with the 21 morphology of the coating. The initiation mechanism of electroless deposition on mild steel was 22
Experimental Investigations on Electro less Plating of Nickel on Steel
2015
Electroless nickel plating on steel is carried out by a chemical reaction and without the use of an external source of electricity. In electroless nickel plating, nickel chloride will come as a metallic salt and is reduced by using Sodium hypophosphite as the reducing agent to nickel metal, which then is deposited on the steel. This process has now become an established industrial technique and gained increasing importanc. By such means not only pure metals but also alloys can be deposited on ferrous and non-ferrous materials to improve their surface characteristics. By using appropriate peeplate treatment methods, a wide range of plastics and ceramics can also be plated by electroless methods. These processes have particular advantages in the field where galvanic processes can only be used at great expense or where they fail completely. The present paper studies the effect of different process parameters during electroless plating of nickel on steel. The effect of bath temperature,...
2017
This study is focused on the investigation of the possibilities for materials surface properties enhancement by electrolees nickel plating method. Substrates of steel 17CrNiMo6 are used for the manufacture of the specimens. Electroless method EFTTOM-NICKEL is applied for the development of an innovative technology for production of as plated nickel and composite Nickel coatings. Detonation nanodiamond particles (ND) are used as a strengthening material for production of composite nickel coatings. Suspension of ND is added directly to the electroless bath using a suitable surfactant to achieve well-dispersed particles in the bath and to facilitate their embodiment and equal distribution in the coating. The influence of ND particles on the coatings mechanical and physical properties is confirmed by the results achieved carrying out as morphology and microstructure observations by optical metallography and scanning electron microscopy (SEM) and also wear and nano indentation tests. The...
8 ELECTROLESS DEPOSITION OF NICKEL
Electroless (autocatalytic) plating involves the presence of a chemical reducing agent in solution to reduce metallic ions to the metal state. The name electroless is somewhat misleading, however. There are no external electrodes present, but there is electric current (charge transfer) involved. Instead of an anode, the metal is supplied by the metal salt; replenishment is achieved by adding either salt or an external loop with an anode of the corresponding metal that has higher efficiency than the cathode. There is therefore, instead of a cathode to reduce the metal, a substrate serving as the cathode, while the electrons are provided by a reducing agent. The process takes place only on catalytic surfaces rather than throughout the solution (if the process is not properly controlled, the reduction can take place throughout the solution, possibly on particles of dust or of catalytic metals, with undesirable results).
Autocatalytic electroless nickel-boron plating on light alloys
Surface and Coatings Technology, 2000
Light alloys are more and more widely used, notably in aeronautics and the car industry. To improve their superficial properties, they can be covered with a hard and wear resistant protective layer. In this article, we examine the possibility of depositing a thick autocatalytic electroless Ni-B plating on aluminium alloys. We propose an alkaline bath containing sodium borohydride as the reducing agent. The deposition rate is held constant by a regular replenishment of the Ni-B bath allowing a rate of about 25 mm/h. The Knoop microhardness of the Ni-B deposits after the bath reaches about 750 hk 100 . Appropriate heat treatment can increase the deposit microhardness up to more than 1000 hk 100 but must be applied with regard to the substrate properties. The study of these heat treatments will be published in a further paper.
Determination of electroless deposition by chemical nickeling
Metalurgija, 2013
Increasing of technical level and reliability of machine products in compliance with the economical and ecological terms belongs to the main trends of the industrial development. During the utilisation of these products there arise their each other contacts and the interaction with the environment. That is the reason for their surface degradation by wear effect, corrosion and other infl uences. The chemical nickel-plating allows autocatalytic deposition of nickel from water solutions in the form of coherent, technically very profitable coating without usage of external source of electric current. The research was aimed at evaluating the surface changes after chemical nickel-plating at various changes of technological parameters.