A. N. Astapov, B. E. Zhestkov, V. A. Pogodin, I. V. Sukmanov
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引用次数: 0
Abstract
The oxidation resistance of a coating, which is formed by firing deposition of layers from a ZrSi2–MoSi2–ZrB2–Si powder mixture, on a C/C–SiC composite substrate is studied. Oxidation resistance tests are carried out under interaction with a high-speed air plasma flow at temperatures up to 2200°C. The performance of the coating is ensured by the formation (and evolution during operation) of a heterogeneous oxide film based on borosilicate glass modified with zirconium, which is an efficient barrier to oxygen diffusion and promotes the passivation of oxidation processes. An increase in the operating temperatures above 1750–1800°C leads to glass phase evaporation from the surface and the formation of a porous thermal barrier layer based on ZrO2 and containing secondary phases Mo/MoO2, Mo3Si, and Mo5Si3. The temperature gradient across the coating thickness favors partial preservation of the glass phase in the inner layers due to a decrease in the vapor pressure, which results in the retardation of oxygen diffusion deep into the material. The temperature–time ranges of performance; the characteristics of mass loss, catalytic activity, and emissivity of the coating; and the main factors limiting the efficiency of its protective action are determined.
期刊介绍:
Russian Metallurgy (Metally) publishes results of original experimental and theoretical research in the form of reviews and regular articles devoted to topical problems of metallurgy, physical metallurgy, and treatment of ferrous, nonferrous, rare, and other metals and alloys, intermetallic compounds, and metallic composite materials. The journal focuses on physicochemical properties of metallurgical materials (ores, slags, matters, and melts of metals and alloys); physicochemical processes (thermodynamics and kinetics of pyrometallurgical, hydrometallurgical, electrochemical, and other processes); theoretical metallurgy; metal forming; thermoplastic and thermochemical treatment; computation and experimental determination of phase diagrams and thermokinetic diagrams; mechanisms and kinetics of phase transitions in metallic materials; relations between the chemical composition, phase and structural states of materials and their physicochemical and service properties; interaction between metallic materials and external media; and effects of radiation on these materials.