Optimization of Characteristics of Pyrolytic Chromium Carbide Coatings

Abstract

The optimization of characteristics of pyrolytic chromium carbide coatings (PCCCs) for various fields of industry is discussed. The scope of PCCC application involves the protection of the surface of various details and units made from different materials against corrosion, sticking, high temperatures, and various types of wear. Such versatility of PCCCs is caused in particular by their structural features, which usually represent the superlattice of alternating relatively hard and soft layers, which differ in composition and, accordingly, functional characteristics, such as microhardness or Young modulus. Such a structure at particular periods and layer-thickness ratios corresponds to the maximum figure of merit of the problem of optimal control theory (OCT), which represents the inverse problem stated on the class of solutions of primal problem, which models specific interaction, e.g., abrasive wear. In this case, the primal problem, e.g., indentation description, is an ill-posed inverse problem of mathematical physics, and another optimal strategy is required to solve it. Thus, a hierarchy of optimization algorithms arises and, using it, one can achieve highest functional characteristics of PCCCs. If the primal problem of abrasive wear could not be formalized, a calculation–experimental method developed by the authors, which is also based on OCT, is suggested. The main emphasis is on improving the deposition technology of PCCCs for each specific application using the optimal control theory. In order to obtain a PCCC fulfilling these conditions, it is necessary to consider the physicochemical features of pyrolysis of precursors, as well as the effect of various additives and catalysts on the development of flow process.