Studies on the Development and Characterization of Ni–Cr Alloys for Fuel Cell Applications

Abstract

Electrodeposition of Ni-Cr alloy has been carried out from acidic sodium citrate complex bath solution in the current density range 5-50 mA/cm 2 at 303 K. The deposited alloys are characterized by cyclic voltammetric and polarization studies. The coatings exhibit as novel electrode material with low overpotential ͑͒ and good corrosion resistance for anodic oxidation of methanol in H 2 SO 4 medium. The anodic peak current, a measure of oxidation reaction rate, is considerably high on Ni-Cr alloy when compared to pure Ni. Chromium is a versatile metal with inherent useful tailor-made properties. It forms alloys with nickel ͑Nichrome-Ni-Cr͒ which are promising materials as resistor elements 1 and find application in high-temperature oxidizing environments. 2Electroplating of Cr/Ni-Cr from aqueous solution has several disadvantages; it is not eco-friendly ͑use of Cr 6+ ͒, it is not economically viable ͑very low cathodic efficiency͒, and the quality of coating is very poor ͑due to H 2 evolution͒.3 Review of literature indicates the need for a comprehensive understanding of plating technology of Cr/Cr-Ni by using less toxic Cr 3+ ions. It is known that the codeposition H 2 during plating of metals is considerably reduced by the presence of a mixture of H 3 BO 3 and NaCl.4 Based on the facts, attempts have been made to electroplate good-quality Ni-Cr alloys. 5Fuel cell ͑nonconventional energy source͒ technology has made considerable progress in recent years in order to meet the global energy demand. 6 Attempts have been made in our laboratory to develop simple and cost-effective electrochemical procedures to get good-quality alloys as electrodes for methanol oxidation fuel cell.7-10 By varying the deposition conditions, it is possible to get Nichrome ͑Ni/Cr͒ with traces of oxides of Cr and Ni or both, 11,5 which are supposed to be potential candidates to function as effective anodes for electrochemical methanol oxidation. Hence, electrodeposition procedures developed earlier 5 are used to prepare thin films of Ni-Cr alloy and tested for their corrosion resistance toward highly corrosive fuel-cell electrolytes and also for electrochemical catalytic activities for methanol oxidation. ExperimentalAll solutions were prepared by using analytical reagent grade chemicals and double-distilled water. Alloys of Ni-Cr were deposited onto copper foils ͑99.9%, 10 ϫ 10 ϫ 0.5 mm͒. Before deposition, copper foils were precleaned by procedures described elsewhere.12 Experiments were carried out using a threecompartment glass cell of 50 mL capacity at 303 K for 30 min. pH of the bath solution was adjusted to 3.0 by using diluted NaOH/H 2 SO 4 . The phases of deposited alloy were studied by X-ray diffractometer ͑XRD͒ ͑Simen D5005 with Cu K␣ radiation͒. Galvanostatic polarization and cyclic voltammetric ͑CV͒ experiments were conducted using a potentiostat/galvanostat ͑EG & G PAR 362͒. A large platinum foil and saturated calomel electrode were used as auxiliary and reference electrodes, respectively. A finely drawn Luggin capillary was use...

Tribological Behaviors of Amorphous Cr Coatings Electrodeposited from Cr(III) Baths under Ionic Liquid Lubrication

“…The good friction reduction performance of the ionic liquid can be attributed to the following reasons: ͑i͒ the ionic liquid, which possesses the unique dipolar structure, can be easily adsorbed on the sliding surface to form an effective boundary film resulting in friction reduction, 1 ͑ii͒ the adhesive forces among ions of ionic liquid may be smaller than that among normal oil molecules due to the repulsion of similar electric charges, ͑iii͒ some antiscratch components such as fluoride and BN resulted from tribochemistry reaction are formed. 1,12 Antiwear property of the a-Cr coatings under ionic liquid lubrication is emphasized in this work. Table I shows the hardness of the specimens.…”

“…1,2 However, Cr͑VI͒ plating process must be substituted for its intense toxicity and carcinogenicity. Of many potential technologies, the Cr͑III͒ plating process is considered as a very promising technology to replace conventional Cr͑VI͒ plating process.…”

Characterization and corrosion behavior of Ni-Cr coatings by using pulse current electrodeposition

“…Ni-Cr alloy coatings are promising materials for their great corrosion resistance and enhanced mechanical properties (Lin, 1992; Tharamani and Mayanna, 2006). This coating is usually prepared by electroplating in a bath containing chromium and nickel ions (Deng and Gong, 2003; Mousavi et al , 2012).…”

An Experimental Study of Sintered (Ni-Cr-xAl2O3) Composites

“…Metal matrix composites are very promising materials in obtaining excellent mechanical properties over the alloys and metals for multi aerospace, marine and automotive applications [3][4][5][6][7]. In the current work, an attempt has made to fabricate a new metal matrix composite material.…”