A surface study of amorphous chromium films electrodeposited from chromic acid solutions. Part I

Abstract

Articles you may be interested inSurface electronic structure in transition-metal (Cr and Mn) doped GaAs (001) studied by in situ photoemission spectroscopy Appl. Phys. Lett. 88, 192506 (2006); 10.1063/1.2202388Spin-polarized scanning tunneling microscopy and spectroscopy study of c ( 2 × 2 ) reconstructed Cr(001) thin film surfaces Evidence of a topological antiferromagnetic order on ultrathin Cr(001) film surface studied by spin-polarized scanning tunneling spectroscopy A previous study demonstrates that the addition of organic compounds containing a -CHO or -COOH group to a Cr plating bath results in a chromium deposit which has greatly improved properties. Such deposits have fewer defects than chromium layers produced by conventional methods, the hardness of these deposits increases with increasing annealing temperature in the range of 100 to 6OO·C and they are more resistive to corrosion by hydrochloric acid than conventional deposits. In this study the composition and chemical interactions of a chromium layer prepared using this new method were examined with Auger electron spectroscopy (AES) and electron spectroscopy for chemical analysis (ESCA) before and after vacuum annealing at 700·C and after argon-ion bombardment. S, C, 0, CI, N, and Ca are incorporated into the deposits from the electrolytic bath. Cr is present as oxides, sulfide, and metal. Annealing causes segregation of S to the surface and diffusion of oxygen into the bulk. This results in conversion of the surface chromium oxides into Cr 2 S 3 and metallic Cr. C also segregates to the surface during annealing forming chromium carbide.

Oxidation of Cr–C electroplating between 400 and 900 °C in air

“…-COOH and C-Cl have similar binding energies (E b of C 1s ¼ 288.3 eV). The presence of carbon in a graphite form was also previously reported in the Cr-C deposits [4]. The asymmetric, broad O 1s spectrum peak (E b ¼ 531.7 eV) indicates that more than one oxygen-containing species are involved.…”

“…It is however noted that the quantitative analysis of a light element like carbon is notoriously difficult. Figure 4 shows the XPS spectra of the Cr-C deposits before and after oxidation at 700 8C for 2 h. Figure 4a indicates that the electrodeposit consists of metallic Cr (E b of Cr 2p3/2 ¼ 574 eV), Cr 2 O 3 (surface oxide film, E b of Cr 2p3/2 ¼ 576.9 eV), C-Cr with a carbide bond (E b of C 1s ¼ $282.6 eV) [7], graphite (E b of C 1s ¼ 285 eV) and probably either carboxyles (-COOH from potassium formate) [4] or C with Cl (from potassium chloride). -COOH and C-Cl have similar binding energies (E b of C 1s ¼ 288.3 eV).…”

“…The asymmetric, broad O 1s spectrum peak (E b ¼ 531.7 eV) indicates that more than one oxygen-containing species are involved. Oxygen is probably in the form of -COOH, adsorbed H 2 O or Cr 2 O 3 [4]. In the Cr-C deposit, there exists oxygen segregated at the outermost surface [3].…”

“…The chromium salts used in trivalent chromium baths are usually chromium sulphate (Cr 2 (SO 4 ) 3 Á nH 2 O) [1] or chromium chloride (CrCl 3 Á6H 2 O) [3]. The organic additives containing the -CHO or -COOH group produce supersaturated carbon in the Cr deposit, resulting in it having an amorphous structure [4,5]. In this study, the amorphous Cr-C deposits were electroplated from the trivalent chromium bath, and oxidized at high temperatures of between 400 and 800 8C in air in order to study their oxidation characteristics.…”

Composition of Chemisorption Layers Forming on a Chromium Electrode in Sulfuric Acid Solutions of Formaldehyde and Formic, Oxalic, and Glyoxylic Acids

“…Earlier, it was revealed with the aid of the method of XPS that in amorphous coatings deposited out of formate and oxalate electrolytes carbon atoms undergo structurization in different fashions, forming both graphite and carbide-like structures [4,[10][11][12]. In view of this situation, in the present work it was expected to find out at which stage of an electrocatalytic process such a specific manifests itself.…”