Materials Science, Vol. 44, No. 2, 2008 COMPUTER MODELING OF THE NONCHROMATE TREATMENT OF ALUMINUM ALLOYS BY NEURAL NETWORKS M. V. Ved’, 1 M. D. Sakhnenko, 1 V. V. Shtefan, 1 S. B. Lyon, 2 S. V. Oleinyk, 3 and L. M. Bilyi 4 UDC 621.35:620.1 We analyze the thermodynamic characteristics and specific features of the course of reactions of oxometalate reduction on the aluminum surface and the properties of the final products (the spe- cific electric resistance of oxides). The absence of a correlation between the ranged series of these parameters led to the necessity of using artificial intellect for modeling the processes of formation of conversion coatings. We obtained and visualized in 3D space the dependences of the corrosion resistance of D16 alloy on the oxometalate concentration, pH, the time of sealing, and test duration. Artificial neural networks based on multilayer perceptrons were used for pre- dicting the corrosion resistance of conversion coatings. Some aluminum alloys (V95, D16, D1, AK-6), due to the features of their structure, are susceptible to layer corrosion, which propagates as a result of the insufficient efficiency of protective coatings [1]. The most wide- spread method of protection of aluminum alloys consists of chemical [2] or electrochemical oxidation with sub- sequent sealing of oxide films (OF), which, unlike conversion coatings, have enhanced hardness and wear resist- ance. To decrease the porosity of oxide films, they are sealed in distilled water and solutions containing oxoani- ons of passivating (phosphates, polyphosphates, and silicates [3]) or oxidizing (predominantly oxometalates: chromates and dichromates, permanganates, molybdates, tungstates, vanadates, etc. [1, 4]) action. In the case of application of anions of the first type, insoluble compounds are formed in the pores of an OF, especially for high alkalinity of the medium due to hydrolysis. If oxometalates are present in the pores of an OF, aluminum is oxi- dized, mixed oxides are formed, and, as a result, the corrosion resistance of the system increases. The efficiency of the action of oxoanions would correlate with their oxidizing ability, i.e., with the values of oxidation-reduction potentials, as for coatings on steels [5]. However, as established in [6], in the case of inhibition of zinc corrosion in alkaline and neutral media by various oxometalates, the efficiency of the process under consideration in- creases if, in the course of oxoanion reduction, a certain excess of OH – ions is formed. Since aluminum is also an amphiprotic metal, we may anticipate the same processes on its surface as well. In view of the necessity of finding substances that are alternatives to ecologically dangerous chromium (VI) compounds, which are widely used in industry for conversion coatings on aluminum alloys, it is important to preserve the efficient protection of the metal. For this purpose, it is necessary to study comprehensively and model the nonchromate treatment of aluminum alloys. 1 “Kharkivs’kyi Politekhnichnyi Instytut” National Technical University, Kharkiv, Ukraine. 2 University of Manchester, Manchester, Great Britain. 3 Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia. 4 Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, Lviv, Ukraine. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 2, pp. 57 – 61, March – April, 2008. Original article submitted May 20, 2006. 216 1068–820X/08/4402–0216 © 2008 Springer Science+Business Media, Inc.