The Journal of Middle East and North Africa Sciences 2016; 2(2) http://www.jomenas.org 16 Electroless and Corrosion of Nickel-Phosphorus-Tungsten Alloy M.S. Ali Eltoum Department of Chemistry, Faculty of Science, Sudan University of Science and Technology, Khartoum, Sudan abotrteell74@gmail.com Abstract: At the present work Nickel-Phosphorous- tungsten alloy was electroless plaiting on copper substrate, different parameters which affect the electroless plaiting of this alloy were studied and the obtained coatings were characterized using different analytical techniques such as EDX (Energy Dispersive X-ray), XRD (X-ray Diffraction), SEM (Scanning Electron microscope), Potentiodynamic polarization curve (corrosion resistance), incorporation of tungsten on Ni-P matrix changed the crystallography and microstructure details of Ni-P ally and enhancement in corrosion and hardness were observed. To cite this article [Ali Eltoum, M. S. (2016). Electroless and Corrosion of Nickel-Phosphorus-Tungsten Alloy. J. Middle East North Afr. sci, 2(2), 16-24]. (p-ISSN 2412- 9763) - (e-ISSN 2412-8937). http://www.jomenas.org. 2 Keywords: Electrolessplting; Polyalloy; Potentiodynamic polarization; Corrosion. 1. Introduction Development of electroless nickel polyalloy deposits is considered as the most effective method to alter the chemical and physical properties of binary Ni-P alloy deposits. The transition metal is the preferred choice because of its high melting temperature, and, unusual mechanical properties. It is a well-established fact that W cannot be electrodeposited from aqueous electrolytes, but can be codeposited with iron group metals such as nickel to form an alloy (Brenner, 1963), this is classified as induced codeposition. Electroless ternary alloy with elements other than the iron family, namely, Ni-W-P, has been first reported by Pearlstein, Weightman, and Wick (1963). Codeposition of tungsten in binary Electroless Ni-P deposit improves the deposit characteristics such as wear resistance. The properties of the electroless Ni-W-P amorphous deposits were determined (Bangewi, Wangyu, Qinglong, & Xuanyuan, 1996). Ni-P based alloy films was prepared by autocatalytic plating and their structure, chemistry and corrosion behaviors in sulfuric acid solution were studied as a function of their composition (Lu & Zangari, 2002). The as- prepared Ni-based alloys are nanocrystalline, and their grain size decreases with increasing P content. The Addition of a third element (W or Mo) influences the observed grain size. Electroless deposition of Ni–W–P alloy coatings onto metal substrates using H2PO-2 as reducing agent from solutions containing nickel sulfate, sodium tungstate, sodium citrate, ammonium sulfate and other additives was studied (Du & Pritzker, 2003). Electroless Ni-P-W coatings were deposited on mild steel in alkaline solutions have been reported (Tien, Duh, & Chen, 2004). The tungsten addition into the nickel-phosphorus based coating, effectively, increases micro hardness and thermal stability (Balaraju & Rajam, 2005). They also possess good magnetic properties. The effect of copper and tungsten in alkaline electroless nickel baths has been studied in depositing Ni-Cu-P and Ni- W-P alloys and also the synergistic effect of ions in depositing Ni-W-Cu-P alloys (Balaraju & Rajam, 2005). Autocatalytic ternary Ni-Sn-P, Ni-W-P and quaternary Ni-W-Sn-P films were also studied (Balaraju & Rajam, 2006).Alkaline citrate-based baths were used and compared with binary Ni-P coatings, excellent properties such as high hardness, wear and corrosion resistance, a lot of interest has been created in the scientific community in developing electroless nickel alloys Hypophosphite reduced baths become more popular for many industrial applications due to their stability, ease of operation, and cost effectiveness.