Influence of calcium on oxidation kinetics of AK12M2 alloy in a solid state

The solution of many problems of modern technology is associated with the use of materials with high oxidation resistance. Therefore, the study of interaction of oxygen with metals and alloys has a great importance in connection with the widespread use of new materials with special physical and chemical properties in various fields of science and technology. In this article, a special place is given to aluminum-silicon alloys. The kinetics of oxidation of AK12M2 alloy modified to 1.0 wt % of calcium has been studied by means of thermogravimetry method. It has been shown that calcium additions and temperature increasing increase the rate of oxidation of initial alloy in the solid state. The effective activation energy of oxidation process of AK12M2 alloy is 127.73 kJ / mol and decreases to 82.11 kJ / mol for the alloy with 1.0 wt % Ca. Oxidation curves of AK12M2 alloy with calcium in the solid state have been described by polynomials indicating the hyperbolic mechanism of this process. The mechanism of influence of calcium on oxidizability of AK12M2 alloy has been established, which consists in the fact that within 0.3-1.0 wt % calcium plays a dominant role in formation of an oxide film characterized by low protective properties. This effect of calcium is due to its physical and chemical properties as an alkaline earth metal. (author)