Corrosion and electrochemical properties of binary cobalt and nickel alloys
- PDF / 265,141 Bytes
- 4 Pages / 595.276 x 793.701 pts Page_size
- 33 Downloads / 236 Views
CORROSION AND ELECTROCHEMICAL PROPERTIES OF BINARY COBALT AND NICKEL ALLOYS M. V. Ved’, T. O. Nenastina, V. V. Shtefan, T. M. Bairachna, and M. D. Sakhnenko
UDC 621.35
The influence of pH of electrolyte on the tungsten content and current efficiency of a Co– W coating is determined. We determine the corrosion rates of Co – W and Ni– Pd alloys by the polarization resistance method and show that the coatings are classified as belonging to highly corrosion-resistant coatings. The catalytic reactivity of coatings in a model reaction of hydrogen release is assessed. Dependences of the corrosion resistance and catalytic reactivity of Co – W and Ni – Pd alloys on the contents of the components are obtained, and their character is justified.
Electroplates from alloys predominantly surpass metallurgical analogs in functional properties. This can be explained by the influence of synthesis conditions on the structure and morphology of the surfaces of materials. The electrochemical technologies enable one to control flexibly the content of alloy-forming components, their codeposition rate, and the state of the surface by varying both the compositions of electrolytes and regimes of polarization (from galvanostatic to pulse polarization or with current reverse). The electrochemical methods not only favor the realization of transitions between links of the interdependent chain process parameters–composition and structure of the material–properties–functions–use, but are also the base of monitoring and control of the development of transformations. Using such a method, coatings from alloys of different qualitative and quantitative compositions with a set complex of properties (synergetic and additive), namely increased strength, hardness, wear and heat resistance, high chemical resistance, catalytic reactivity, etc., are formed on substrates (carriers) of different nature. It was assumed [1] that synergetic alloys (predominantly intermetallics) are formed by metals that differ in the degree of occupation of d-orbitals and that their catalytic reactivity can be foreseen from the energies of the crystal lattices. In our opinion, for the modeling and prediction of properties of complex heterogeneous systems that do not follow the laws of additivity, it is necessary to use a larger number of factors and a set of nonlinear probabilistic-statistical methods. Below we investigate the influences of the electrolysis regimes on the composition and properties of alloys formed by metals of different (Co – W) and similar (Ni – Pd) electronic structure for the development of an algorithm for predicting the catalytic reactivity and corrosion resistance of the materials. Experimental Technique We deposited coatings from a Co – W alloy (5 – 9 μm thick) and from a Ni – Pd alloy (2 – 3 μm thick) on samples of Kh18N10T steel after a preliminary forming treatment performed by a known technique [2]. The Co – W coatings were deposited from a citrate electrolyte at pH varied in the range 5 – 11 and a temperature varied in the range 333 – 353 K with un
Data Loading...
