Electroless Deposition of Nanolayered Metallic Coatings

Electroless metallic coating is referred as the deposition of a substrate material by the process of chemical or autocatalytic reduction of aqueous metal ions deposited to a substrate material without any external supply of power. Electroless nickel alloys are generally considered synonymous to the word “electroless coating” as ~90% of productions in industries are of this alloy coating. Rest of the electroless metallic coatings includes gold, copper, palladium, cobalt, silver, etc. These electroless metallic coatings (other than electroless nickel coatings) are also one of the vibrant areas in the field of materials properties and surface engineering research. From the year 2000 to till date, nearly 1000 SCI indexed research papers were published on this topic. However, no comprehensive studies about the recent progress on this topic were reported elsewhere so far. In this context, the present chapter aims to give a complete overview on various aspects of the rest of the electroless metallic nanocoatings/layer as a whole. More importance will be on the recent developments of the nanocharacteristics and future scopes

Dry sliding wear properties of a 7075-T6 aluminum alloy coated with Ni-P (h) in different pretreatment conditions.

Dry sliding wear behavior of electroless nickel-phosphorus (EN) coating of thickness ~35 lm deposited on a 7075-T6 aluminum alloy was studied. EN was deposited from a bath with sodium hypophosphite as a reducing agent. In as-deposited conditions, plating with 6-9 wt.% phosphorus has a mixture of amorphous and microcrystalline phase. Three pretreatments of Zn (zincate), Ni strike and absorbed hypophosphite layer were given to the substrate before EN coating to examine their wear performance. The surface morphology of the pretreatments was studied by a confocal laser scanning microscope. The performances of these pretreatments of EN were evaluated by dry sliding wear studies and followed by SEM studies. The results suggest that the wear behavior of EN mostly depends on the pretreatment conditions. Heat treatment at temperature of 400 oC can enhance the wear resistance properties for all types of pretreatment conditioned samples and in addition that the average coefficient of friction of 400 oC specimens (lav) had minimum value as compared to 200 oC specimens. Ni strike provided better interlocking adhesion between EN and Al and this pretreatment noticeably improved the wear, frictional and hardness behavior of the EN coatings on 7075 Al substrate and further enhanced it by heat treatment of 400 oC/h

A review of electroless coatings on non-metals: Bath conditions, properties and applications

The electroless coatings on the non-metal surface possess the desired properties for various applications in the aerospace, marine, medical, automotive, textile, electronics, household and food industries. Many researchers have developed the coating on non-conducting materials for many applications, and it has established its potential since its invention. This review started with fundamentals and their historical backgrounds. The work carried out on polymer, glass and ceramics is crtically reviewed. The optimized bath conditions developed for coating on the various non-metal substrates are populated for reference to future research works. The various properties of the developed coating, such as tribological, mechanical, electrical, and thermal, are addressed in line with their applications. The most recent applications of electroless coating on non-metals are reviewed. Finally, the future application of the electroless coating in emerging technologies is also discussed.</p