Uniform, adherent, crack-free and non-bridging HfC and HfC/SiC coatings on carbon fibers have been synthesized by a reactive CVD (RCVD) process at low temperatures. To fabricate SiC coating on HfC-coated carbon fiber, an alternative approach using unsaturated organosilicon polymer solution was also proposed. The schemes describing the formation of carbide coatings on carbon fibers by RCVD and transformation of unsaturated organosilicon polymers into silicon carbide are discussed. The HfC and HfC/SiC coatings were studied by SEM, EDS and XPS techniques. Coatings are composed of hafnium, silicon and carbon as the main constituents and oxygen and fluorine as contaminants. As was proposed, the composition of the coatings is affected by several factors, among them a chemical attack of coated fibers by gaseous oxygen- and fluorine-containing by-products can be considered as dominant ones. The duplex HfC/SiC-coated carbon fibers exhibit more oxidation resistance at elevated temperatures than the initial and HfC-coated carbon fibers.

Sols of yttria-stabilized zirconia may be used as simple, readily processable and accurate controllable precursors for the ZrO2 interfacial coatings on SiC-based Nicalon™ fibers. The ZrO2 interfacial coatings of predictable crystal phase compositions were obtained in dependence of yttria dopant level. The morphology, composition and oxidation resistance of coated fibers were evaluated by SEM, EDS, XPS, XRD, and Raman analysis. All coatings obtained are uniform, continuous and adherent to substrates. The delamination within the ZrO2 interfacial coating was found. Possible reasons of this phenomenon are discussed. The peculiarities of the behavior of Y-stabilized ZrO2-coated fibers in air at elevated temperature are considered.

The results of study of the surface chemistry of nanodiamonds treated by a mixture of HClO(4) and H(2)SO(2) acids are presented. Changes of the composition of surface diamond groups brought up by thermal annealing were monitored by Fourier transformed infrared spectroscopy and temperature-programmed desorption. The decomposition of oxygen-containing groups is observed at 300-900 degrees C; CH. groups decompose at 700-1150 degrees C. The process of the annealing of ND was investigated by the X-ray photoelectron spectroscopy. The clear onset of ND graphitization was observed at temperature of 950 degrees C that is supported by the appearance of sp(2) component in the Cls spectrum. The presence of the N1s peak in spectra of ND is observed in initial and partially graphitized ND annealed up to 1100 degrees C.

Sols of alumina, zirconia, titania and their mixes may be used as simple and readily processable precursors for ceramic interfacial coatings on SiC-based Nicalon™ fibers. The morphology, composition and tensile properties of coated fibers were evaluated for different systems in dependence of processing conditions by SEM, XPS, XRD analysis. All coatings obtained are uniform, continuous and adherent to substrates. They are distinguished by their morphological features, tensile strength, thermal resistance and compatibility with fiber. The peculiarities of the behavior of oxide-coated fibers are governed by the properties of initial sols, procedure for coating fabrication, chemical and nanostructural factors.

The particularities of the formation of alumina, zirconia and mixed oxide sol-gel derived interfacial coatings on Nicalon fibers were studied by SEM, XPS, XRD analysis. Alumina, zirconia and mixed oxide coated Nicalon fibers are distinguished of their morphology, tensile strength and thermal oxidation resistance. The difference depends not only on the composition but also on the nanostructure of coatings.

Different carbon materials have shown unusually high efficiency of electron field emission. The device application of the carbon cold cathodes requires a fundamental understanding of the emission mechanism. We describe the emission properties of carbon thin films grown by chemical vapor deposition. The structure, phase composition and electronic properties peculiar to the film material were investigated. New model of electron emission sites and mechanism of field electron emission are proposed. In accordance with the proposed model the electron emission in carbon materials occurs from sp3-like defects in an sp2 network of graphite-like material. The corresponding mechanism of field emission consists of electrons escaping into vacuum by tunneling from the Fermi level of the graphite material through the atomically thin sp3-like layer and the energy barrier on its surface.