P. Mogilevsky

Bio: P. Mogilevsky is an academic researcher from University of Illinois at Urbana–Champaign. The author has contributed to research in topics: Ceramic & Oxygen permeability. The author has an hindex of 1, co-authored 1 publications receiving 16 citations.

Modeling of oxidation behavior of SiC-reinforced ceramic matrix composites

Abstract: Internal oxidation of SiC reinforcement is a major factor affecting the environmental stability of SiC reinforced ceramic matrix composites (CMCs) for high temperature applications. A simple phenomenological model describing the unidirectional oxidation of SiC reinforced oxide CMCs is presented. The model allows to calculate the thickness of the silica layer formed on a SiC reinforcement as a function of its location (depth beneath the surface) and time, if the oxygen permeabilities of silica and the matrix are known. The oxidation mode can thereby be predicted. Alternatively, the model allows to evaluate the oxygen permeabilities of silica and the matrix from the experimental oxidation data. Moreover, the expected mode of oxidation, I or II, can be predicted depending on oxygen permeabilities and volume fraction of the reinforcement phase. Application of the model to the results of the microscopic study of the oxidation of SiC reinforced mullite–zirconia matrix composites allowed to evaluate oxygen permeabilities of the matrix and of the growing silica layer on the SiC particles. It was found that while oxygen permeability of the silica layer on the SiC particles may depend significantly on the type of SiC reinforcement, it is reasonably close to the values obtained from the experiments on direct oxidation of SiC and permeation through vitreous silica. Oxygen permeability of the mullite–ZrO2 matrix showed a dependence on the microstructure and composition of the matrix.

Advances in self-healing ceramic matrix composites

Abstract: Self-healing is the capacity of a system to repair damage by itself so that cracks are sealed. For ceramic materials, especially ceramic matrix composites (CMCs), cracks can exist after processing or are created by a mechanical or thermal load. At high temperature in a moist oxidizing environment, cracks allow oxygen diffusion inside the bulk, provoking chemical degradation. To limit oxygen progression, an oxide glassy phase is used to fill cracks. This oxide is added as a protective coating or is formed by oxidation of non-oxide compounds in a protective coating or in the bulk. In the latter, the constituent undergoing oxidation acts as a chemical fuse against oxidation. Self-healing remains efficient if the oxide is chemically and thermally stable.

Ceramic matrix composite corrosion models

Abstract: This paper discusses physical and empirical models for the description of corrosion processes. Physical strict models are advantageous for simple ceramics and simple composites. In additive-containing ceramics and composites with such matrices, the transport properties will vary with time; in these cases simple physical models alone are not adequate. The use of an empirical equation of the form x = k 1 t + k' p t + k log log(t), fitted by simple multiple linear regression, is capable to describe many versions of corrosion processes, if k 1 is allowed to become negative or positive (x: scale thickness or specific mass change, t: time). The equation is recommended for complex cases, but the variability of the corrosion function makes it often necessary to have more than one parameter of evaluation of the material to deduce the most important engineering parameter, penetration depths.

High Temperature Oxidation Behavior of Silicon Carbide Ceramic

Abstract: Oxidation thermodynamics of silicon carbide (SiC)ceramic was studied by means of HSC Chemistry code, and the weight change, morphology and phase of oxidation products were analyzed by thermogravimetric analysis(TG), scanning electron microscopy(SEM ) and X-ray diffraction (XRD). The results showed that SiC ceramic could be oxidized to silicon dioxide(SiO2) with release of small molecular gases under oxidizing atmosphere at 800°C, and the formed SiO2 film with appropriate fluidity and low oxygen diffusion coefficient could prevent the spread of oxygen with the oxidation temperature increasing up to 1200°C, which favored the anti-oxidation of SiC ceramic matrix composite.

Thermodynamics and Oxidation Behaviour of Crystalline Silicon Carbide (3C) with Atomic Oxygen and Ozone

Abstract: Thermodynamics of oxidation of crystalline silicon carbide (cubic form) by atomic oxygen (O) and ozone (O3) was derived to understand the thermodynamic stability of SiC in the upper atmosphere. Equilibrium constants and equilibrium partial pressures were computed for each of eight possible reactions of SiC with O and O3. Equilibrium activity diagrams were derived, showing the most stable oxidation products of SiC, represented in temperature-oxygen pressure 2D diagrams. Programs were developed in Mathematica. The diagrams provide an understanding of the oxidation routes of SiC under changing levels of O/O3 and temperature, as encountered during reentry of space vehicles. At high levels of the volatiles, CO2, CO, and SiO and temperatures between 1000 and 1500 K, oxidation by atomic oxygen or ozone first produced SiO2