Features of modification of amorphous metallic alloys by oligomeric coatings

Abstract

By potentiometric method it was investigated the dissolution in 0.5 M NaCl aqueous solution of the initial amorphous metallic alloys Fe 78,5 Ni 1,0 Mo 0,5 Si 6,0 B 14,0 , Со 75.5 Fe 4.5 Si 6.0 B 14.0 , and with the applied oligoperoxide layers. Preliminary chemical cleaning by HF of the surfaces of original amorphous alloy activates their corrosion, and subsequent aging in a solution of KMnO 4 helps to restore the oxide protective layers. In an aggressive environment of sodium chloride oxide films are dissolved and corrosion of the amorphous alloyʼs surface is presented. It is importante to create additional protection of the alloys surface by applying oligomeric layers. After the formation of an oligoperoxide film on such a surface, the value of the stationary potential does not change upon contact with an aggressive medium, which is associated with the creation of additional resistance to the transfer of charged particles. According to electrochemical parameters, the stability of oligoperoxide films was evaluated: vinyl acetate, 2-tert-butylperoxy-2-methyl-5-hexen-3-yne and maleic anhydride (OP-1), vinyl acetate, 3-tert-butylperoxy-3-phenylbutylmethacrylate and maleic anhydride (OP-2) on the investigated amorphous alloys. It was shown that more stable films are formed on the external side of the tape of amorphous alloy, which contains a larger proportion of the crystalline phase. It was established that the stability of the obtained films significantly depends on the concentration of the film-forming solution. With increasing concentration of the oligoperoxide solution, it is possible to change the conformation of the adsorbed macromolecules and rearrange the adsorption layer, which often reduces the density of the film. The densest films are formed on the surface of alloys based on iron with 0,5 % OP-1 aqueous-ammonia solutions of oligoperoxides, and based on cobalt - with 0,1 % solutions OP-1 and OP-2. Keywords: amorphous metallic alloys, oligomeric coatings, potentiometry, corrosion resistance.