A system based on P5827 and PI50 potentiometers and an IBM PC is considered that makes it possible to investigate electrochemical corrosion of metals and alloys. The system can be used for training students and specialists as well as for corrosion investigation, testing, and certification. The software developed can be used in systems for corrosion protection and cor, d.Publications in this country and abroad give convincing evidence of the expediency of the use of electrochemical methods in corrosion tests [ I -3, 5 -I I ]. These methods are based on modern concepts of the processes of electrochemical corrosion and give reliable data on the type, rate, and mechanisms of corrosion processes. Electrochemical methods can be used in accelerated tests and investigations of the majority of metals and alloys in a wide spectrum of corrosion media and conditions.The system comprises software for determining the corrosion current, corrosion rate, and Tafel coefficients under conditions of uniform corrosion and soft-ware for determining the susceptibility to intercrystallite and pitting corrosion. It has been developed in Pascal in MS DOS. The menu of the system is presented in Table 1.The investigation method is chosen using the HELP and EXP.SYS (expert system) regimes.The HELP regime provides information on the essence of the method, the range of its application, the special features of the software, and data on specifications and publications. The EXP.SYS regime provides the choice of the method with allowance for the tasks of the investigation, the composition of the alloy and the corrosion medium, the requisite accuracy of the computation, the possibilities of the available equipment, and the available experimental data. 228In addition to the software the system includes methodological recommendat.ions and specifications for the methods used. METHODS FOR DETERMINING PARAMETERS OF UNIFORM CORROSIONThese methods are based on the Wagner -Traud equation for the case of activation control, namely,where i, A/m 2 is the density of the external current; E is the running value of the potential, V; Eeo r is the potential of free corrosion; E -E~or is the applied potential; i~o ~ is the density of the corrosion current, A/m2; b m is the Tafel coefficient of anodic ionization of the metal, V; b d is the Tafel coefficient of the cathodic depolarization process, V. The method of polarization resistance standardized in ASTMG 59 [2] is the most widely used. it is based on the linear dependence of the current density i on the applied potential (E -Eco r ) at low values of it [(E -Eco ~) < 60 mV]. In this case we can write the following relationship:

Amorphous and nanocrystalline chromium-carbon coatings have higher properties than standard galvanic chromium ones. However, data on these coatings and their heat-treatment regimes are quite scarce. The present paper concerns the structure, microhardness, ductility, adhesion strength, and resistance to overall and pitting corrosion of amorphous chromium-carbon coatings deposited galvanically by various regimes in an electrolyte based on chromic anhydride with an additive of formic acid.Amorphous chromium-carbon coatings can be deposited by introducing formic acid into the bath for electrolytic chrome-plating [1]. These coatings differ substantially from galvanic chromium coatings by the presence of an amorphizing additive, namely, carbon in an amount of 2-4%. Subsequent heating causes crystallization of the amorphous chromium--carbon coatings and formation of a nanocrystalline structure in them.The aim of the present work consisted in optimizing the regimes of deposition of chromium-carbon coatings and their heat treatment by studying their structure and properties.Amorphous chromium-carbon coatings were deposited on steel 08 (0.05-0.12% C, 0.17-0.37% Si, 0.35-0.65% Mn) in an electrolyte composed of 100 g/liter chromic anhydride, 5 g/liter sulfuric acid, and 20 ml/liter formic acid (85% aqueous solution).Before depositing the coating the specimens were polished and then degreased in acetone.The deposition regimes and their characteristics are presented in Table 1.The porosity and the presence of cracks in the coatings were monitored by a metallographic analysis of unetched fiat surfaces of the specimens. The microstructure of the coatings was studied on transverse microsections at a 1000-fold magnification under a Neophot microscope. The microsections were etched in Murakami reagent. The structure and phase composition of the coatings were studied by the x-ray difir'action method using a DRON-1 diffractometer. The microhardness of the coatings was determined on polished transverse microsections in the middle (with respect to the thickness) of the coating using a PMT-3 device under a load of 1 N. The corrosion resistance of the coatings was studied in a 3% aqueous solution of NaCl using a P5827m potentiostat by plotting and processing anodic polarization curves obtained at a scanning rate of 10 mV/min. To evaluate the susceptibility of the coatings to pitting the coatinged specimens were held in a 3% aqueous solution of NaCl for 14 days. The corrosion rate was calculated by the method of polarization resistance [2, 3]. The luster of the coatings was estimated visually on a three-point scale. The coatings with the highest reflectivity were given 3 points.The absence of diffraction peaks and the presence of a halo on the diffractograms obtained from the surface of the specimens indicate that the structure of the coating is amorphons. The coatings have a lustrous uniform surface without chips or bulges. The metallographic analysis did not reveal cracks typical for galvanic chromium coatings, in which cracks appear, i...

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