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Removal of Hypophosphite and Phosphite from Electroless Nickel Plating Baths
Published in John M. Bell, Proceedings of the 43rd Industrial Waste Conference May 10, 11, 12, 1988, 1989
Wei-cbi Ying, Robert R. Bonk, Michael E. Tucker
Electroless nickel plating (EN) is a popular commercial technique for depositing nickel coating on a suitably treated surface by controlled chemical reduction of nickel ions. The nickel coating catalyzes the reduction reaction, and the deposition of nickel continues as long as the substrate remains in contact with the EN solution. Typical EN applications include parts which are difficult to plate, such as valves and machine tools, as well as larger objects, such as caustic railcars and barges.1,2 The physical properties of the coated surface such as coating uniformity, corrosion and wear resistance, lubricity and ductility compare favorably with electroplated nickel surfaces.3
Metal Plating and Surface Finishing
Published in E. Higgins Thomas, Hazardous Waste Minimization Handbook, 2018
The main advantages of electroless nickel plating are that the throwing power is essentially perfect and the deposits provide greater protection of the substrate because they are less porous.3 In addition, the nickel concentrations of electroless baths are approximately one-eleventh those of conventional Watts nickel baths. Therefore, drag-out quantities and sludge production from an electroless bath are much less than from a conventional bath.
Heat treatment and quenching effects on wear of electroless nickel–phosphorous plating
Published in Cogent Engineering, 2021
Abhishek D.. Shetty, B. Shivamurthy, B. H. S. Thimmappa, Yash Parmar
The purity of electroless nickel deposition (generally 92% nickel and 8% phosphorus) is less than the electrodeposition method (99% Nickel). The phosphorus content in the electroless Ni–P coating has a significant effect on the properties. In the case of electroless nickel plating, it is possible to obtain 3% to 12% of P. Based on the P content, one can classify the coatings as low (2–5% P), medium (6–9% P), and high (10–13% P) phosphorus coating. The content of P also influences corrosion resistance, wear resistance, friction coefficient, and hardness of the coating (Buchtík et al., 2019).Further, the content of P is also influenced by the internal residual stress in the coated film. The high content of P leads to compressive stress, while the low content creates tensile residual stress in the coated film. The microstructure of the electroless Ni–P is amorphous in as-plated conditions, and it converts into a fine grain structure after proper heat treatment. This structure also influences the wear resistance of the electroless Ni–P. It has been reported in the literature that, due to Ni–-P coating on steel, improved tremendous wear resistance after heat treatment at 320°C and 400°C (Samuel & Zoppas, 2017; Uday Venkat Kiran et al., 2019).
Coated and uncoated reinforcements metal matrix composites characteristics and applications – A critical review
Published in Cogent Engineering, 2020
Karthik B M, Gowrishankar M C, Sathyashankara Sharma, Pavan Hiremath, Manjunath Shettar, Nagaraj Shetty
Reinforcement surfaces can be coated with non-metallic or metallic compounds, to improve adhesion (wettability), mechanical properties and to evade any unpleasant chemical reaction within the matrix and reinforcement at elevated temperatures. There are different methods of coatings like Electroless Nickel Plating (EN), Chemical Vapour Deposition (CVD), Physical Vapour Deposition (PVD), etc. PVD is a technique where the condensed phase material enters to a material phase of vapour as thin film. Sputtering and evaporation are the most common PVD processes (Navinšek et al., 1999; Sathyashankarasharma et al., 2019; Shankar et al., 2018; S. Sharma et al., 2018). PVD is used for high melting point and low vapour pressure materials. CVD is a deposition method to chemically produce pure, high-performance solid materials. In the general CVD process, the desired output is produced when the substrate reacts and decomposes when exposed to several volatile precursors (Chou & Liu, 2005; Sathyashankarasharma et al., 2019). In Electroless Nickel plating (EN) technique, plating of nickel phosphorous alloy by the process of chemical reduction on the catalytic metal surface. The deposits from EN processes have high corrosion resistance, lower wear surface. They have a noticeable lower amount of porosity, which results in outstanding wearing off and the abrasion resistance of the thickness quotient (S. S. Sharma et al., 2016; Sánchez et al., 2010).
Component fabrication techniques for solid oxide fuel cell (SOFC) – A comprehensive review and future prospects
Published in International Journal of Green Energy, 2022
Alagu Segar Deepi, Srinivasan Dharani Priya, Arputharaj Samson Nesaraj, Anburaj Immanuel Selvakumar
Electroless nickel plating is one of the novel methods merged by the researchers for coating a non-conductive substrate with a nickel layer without the involvement of external electricity (Shong, Liu, and Yang 2012). In this process, the plating is carried out by means of an autocatalytic reaction, which does not require an external electrical current source, and it is an autocatalytic chemical reduction method. During the plating process, the metallic Ni2+ nickel ions are reduced to nickel. The reduced nickel deposits only on the specific surface where the catalyst is present before the beginning of reaction. The autocatalytic nature of the process indicates that the plating is continued as long as the substrate is immersed in the plating bath. The major advantage of this process is that an immeasurable nickel film thickness will be formed without applying a current to the substrate. In its series of involved steps, it uses different concentrated liquids to achieve metal coatings. The nickel sulfate plating bath comprises nickel salt, various complexing agents, buffering agents, and stabilizers. There are three types of electroless nickel plating: nickel–phosphorus, nickel–boron and poly alloys. The non-conductive substrates to be coated are submerged in the nickel plating bath and deposited by the catalytic reduction of nickel ions with sodium hypophosphite. In the aqueous nickel solution, chemical redox reaction occurs between the combination of nickel ions and reducing agent which generates nickel deposition. Mukhopadhyay et al. prepared Ni–8 mol% YSZ cermet through a novel electroless technique, which is used as an anode in SOFCs. The developed anode (28 vol% Ni) is used in two different configurations, viz. anode support and anode active layer (AAL), which reported the highest electrochemical performance of 3.2 A/cm2 with the lowest cell area specific resistance at 800°C. They have reported an anode-supported single cell having an optimized 15 mm electroless anode active layer (Mukhopadhyay et al. 2012).