Wear and friction characteristics of electroless Ni-B-W coatings at different operating temperatures. (28th February 2018)

• Record Type: Journal Article
• Authors: Mukhopadhyay, Arkadeb; Barman, Tapan Kumar; Sahoo, Prasanta
• Is Part Of: Materials research express. Volume 5:Number 2(2018)
• Publication Date: 2018-02-28
• Subjects: electroless -- Ni-B-W -- wear -- COF -- high temperature -- oxide layer; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/aaae5a
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: Sodium borohydride reduced electroless nickel alloy coatings have high wear resistance and low coefficient of friction. The present work investigates the deposition and tribological behavior of a ternary variant of the borohydride reduced coating i.e. Ni-B-W. Electroless Ni-B-W coatings were deposited on AISI 1040 steel substrates. In order to improve the mechanical properties of the deposits, they were heat treated at 350 °C for 1 h. The coatings in their as-deposited and heat treated conditions were characterized by scanning electron microscope, energy dispersive x-ray analysis and x-ray diffraction techniques. Ni-B-W coatings are amorphous in their as-deposited state while they become crystalline on heat treatment. In fact a high microhardness of Ni-B-W coatings is also observed in as-deposited condition. The microhardness further improves on heat treatment. Tribological behavior of the heat treated coatings with varying load (10–50 N), sliding speed (0.25–0.42 m s −1 ) and operating temperature (25 °C–500 °C) were evaluated on a pin-on-disc type test setup while the wear mechanisms were also studied. Tribological behavior of Ni-B-W coatings is enhanced at 500 °C operating temperature in comparison with 100 or 300 °C due to formation of protective oxide scales and microstructural changes due to in-situ heat treatment effect.