Effect of P, B4C, and (Ti, Cr)C Additives on the Kinetics of High-Temperature Oxidation of Chromium Carbide Alloys at 1000°C

Abstract

We have used the thermogravimetric method to study the effect of B4C, (Ti, Cr)C, and phosphorus additives on the kinetics of oxidation of chromium carbide alloys of the type 85% Cr3C2 ― 15% Ni (KKhN15) and 85% Cr3C2 ― 15% (Ni ― P) (KKhNF15), in air under isothermal heating conditions at 1000°C from 0 to 5 h. We have established that the alloys are characterized by insignificant increase in mass in the initial oxidation period (≈3 h), after which the degree of oxidation increases somewhat. The nature of the oxidation kinetics for KKhNF15 alloys, containing 0.016-0.64% B4C, varies from some mass increase in the initial period (≈20 min) to later mass loss in connection with formation of CO, CO2 and rapid evaporation of boron anhydride B2O3. The maximum resistance to oxidation is exhibited by alloys of the type KKhN15 and KKhNF15, the mass increase of which is 0.128-0.256 mg/cm2 after 5 h of heating at 1000°C.