Articles made of carbon materials which exhibit unique physicochemical and mechanical properties are used in various branches of science and technology, i.e., from structural elements for space equipment to everyday articles. With the aim of expanding the range of application for carbon materials, particularly in the field of high-temperature technology, it is necessary to improve their heat resistance. As a rule this problem is resolved either by creating heat-resistant composites (for this purpose corrosion-resistant additions are made to the composition of the carbon matrix) or by applying protective coatings. The second path is assumed to be more promising.Information about multilayer coatings on carbon materials is presented in [1]. A substrate of titanium carbide with a thickness of the order of ten microns was precipitated from a mixture of titanium chloride and methane gases, and a protective coating of molybdenum disilicide with a thickness of 100 #m was applied by plasma deposition followed by annealing. The heat resistance of these coatings in air at 1600°C was of the order of tens of hours. The most promising are multilayer coatings of silicon carbides and nitndes, molybdenum and tungsten silicides, and also zirconium and hafnium oxides [2]. Thesecoatings arecapable ofprotecting carbon-carbonmaterials in oxygen-containing atmospheres at temperaturesup to 1800°C.The aim of the present study is to develop high-temperature and anti-corrosion coatings for carbon materials based on transition metal borocarbides and silicides.Considering the comparatively low linear expansion coefficients for carbon materials, the nonuniformity of their structure, high porosity, and high vapor pressures of carbon oxides with their greater chemical activity, in order to obtain high-temperature and heat-resistant coatings the methods of diffusion impregnation, deposition from the gas phase, and impregnation through the liquid phase and fusion were used. Experience in applying high-temperature (up to 2000°C) protective coatings on refractory metals and their alloys [3-5] was used.The original specimens made of carbon material, in particular graphite grade ARV and graphite bonded with pyrocarbon (GBP), were cylindrical in shape 8 mm in diameter 8 mm and 70 mm high. The carbon-borosilicides of refractory metals were selected as protective coatings. Titanium, niobium, and zirconium for subsequent preparation of a carbide substrate were applied by thermal decomposition from chlorides and iodides in the gas phase. A high-frequency generator or a furnace with an electric heater was used in order to heat the specimens. The temperature was measured by an optical pyrometer of the 'Promin' type or a tungsten-rhenium thermocouple. Titanium (zirconium) iodide was prepared directly in the device for applying coatings by passing iodine vapor through titanium (zirconium) turnings. The layout of the device and the procedure for applying coatings from the gas phase are described in [6]. In order to provide good coating adhesion with the base c...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.