Electrodeposition of Aluminum–Tungsten Alloy Films Using EMIC–AlCl₃–W₆Cl₁₂ Ionic Liquids of Different Compositions

Abstract

Electrodeposition of AlW alloy films with high W contents has been carried out using 1-ethyl-3-methylimidazolium chloride (EMIC) aluminum chloride (AlCl 3) ionic liquids containing tungsten(II) chloride (W 6 Cl 12). Although the corrosion resistance and hardness of the alloy films are expected to be improved with an increase in the W content, dense films with W contents higher than ³12 at% have not been obtained by electrodeposition to date. This study has demonstrated that electrodeposition using a EMICAlCl 3 W 6 Cl 12 bath with a lower AlCl 3 /EMIC molar ratio can yield AlW alloys with higher W contents. The maximum W content of the alloys electrodeposited using the EMIC1.5AlCl 3 bath reached 19.4 at%. The alloy films with up to ³18 at% W were dense and smooth, whereas those with >³18 at% W exhibited increased surface roughness. The hardness and Young's modulus of the dense and smooth 17.7 at% W film were determined by nano-indentation. The hardness of this film was confirmed to be higher than those of the AlW alloy films previously obtained from the EMIC2AlCl 3 baths.

Formation of a photocatalytic WO3 surface layer on electrodeposited Al–W alloy coatings by selective dissolution and heat treatment

“…Among aluminum-based binary alloys, Al–W alloys are known to have the highest resistance to chloride-induced pitting corrosion 4,5 . Al–W alloys have been formed using sputtering 4–11 , ion implantation 12 , laser alloying 13 , and electrodeposition 14–19 . Electrodeposition is advantageous for industrial applications because a thick film can be formed rapidly on a large substrate using uncomplicated equipment.…”

“…Electrodeposition is advantageous for industrial applications because a thick film can be formed rapidly on a large substrate using uncomplicated equipment. Recently, we reported that dense Al–W alloy films with W contents of up to 18 at.% could be electrodeposited from 1-ethyl-3-methylimidazolium chloride (EMIC)–aluminum chloride (AlCl 3 ) ionic liquids containing tungsten(II) chloride (W 6 Cl 12 ) 17–19 .…”