Nano-Structured Carbide-Derived Carbon Films and Their Tribology

Carbide-derived carbon （CDC） is a form of carbon produced by reacting metal carbides, such as SiC or TiC, with halogens at temperatures high enough to produce fast kinetics, but too low to permit the rearrangement of the carbon atoms into an equilibrium graphitic structure. The structure of CDC is derivative of the original carbide structure and contains nanoscale porosity and both sp2 and sp3 bonded carbon in a variety of nanoscale structures. CDC can be produced as a thin film on hard carbides to improve their tribological performance. CDC coatings are distinguished by their low friction coefficients and high wear resistance in many important industrial environments and by their resistance to spallation and delamination. The tribology of CDC coatings on SiC surfaces is described in detail.     

Quantum fluids in nanoporous media—Effects of the confinement and fractal geometry

The complex behavior of such quantum fluids like liquid 4He and liquid 3He in nanoporous media is determined by spatial quantization because of geometrical confinement as well as by significant contribution from the surface atoms. In the present report we will review the procedure, results and discuss the issues for fractionalized nonextensive hydrodynamical approach to describe the properties of quantum fluids inside nanopores and propose consideration of strong correlated quantum liquid by means of fracti...     

Capacitance, charge dynamics, and electrolyte-surface interactions in functionalized carbide-derived carbon electrodes

This study analyzed the dynamics of ionic liquid electrolyte inside of defunctionalized, hydrogenated, and aminated pores of carbide-derived carbon supercapacitor electrodes. The approach tailors surface functionalities and tunes nanoporous structures to decouple the influence of pore wall composition on capacitance, ionic resistance, and long-term cyclability. Quasi-elastic neutron scattering probes the self-diffusion properties and electrode-ion interactions of electrolyte molecules confined in functionalized pores. Room-temperature ionic liquid interactions in confined pores are strongest when the hydrogen-containing groups are present on the surface. This property translates into higher capacitance and greater ion transport through pores during electrochemical cycling. Unlike hydrogenated pores, aminated pores do not favorably interact with ionic liquid ions and, subsequently, are outperformed by defunctionalized surfaces.     

Quantum fluids in nanoporous media——Effects of the confinement and fractal geometry

The complex behavior of such quantum fluids like liquid 4He and liquid 3He in nanoporous media is determined by spatial quantization because of geometrical confinement as well as by significant contribution from the surface atoms. In the present report we will review the procedure, results and discuss the issues for fractionalized nonextensive hydrodynamical approach to describe the properties of quantum fluids inside nanopores and propose consideration of strong correlated quantum liquid by means of fractionalized Schro¨dinger equation.     

Conversion of silicon carbide to crystalline diamond-structured carbon at ambient pressure

Synthetic diamond is formed commercially using high-pressure, chemical-vapour-deposition and shock-wave processes, but these approaches have serious limitations owing to low production volumes and high costs. Recently suggested alternative methods of diamond growth include plasma activation, high pressures, exotic precursors or explosive mixtures, but they suffer from very low yield and are intrinsically limited to small volumes or thin films. Here we report the synthesis of nano- and micro-crystalline diamond-structured carbon, with cubic and hexagonal structure, by extracting silicon from silicon carbide in chlorine-containing gases at ambient pressure and temperatures not exceeding 1,000 degrees C. The presence of hydrogen in the gas mixture leads to a stable conversion of silicon carbide to diamond-structured carbon with an average crystallite size ranging from 5 to 10 nanometres. The linear reaction kinetics allows transformation to any depth, so that the whole silicon carbide sample can be converted to carbon. Nanocrystalline coatings of diamond-structured carbon produced by this route show promising mechanical properties, with hardness values in excess of 50 GPa and Young's moduli up to 800 GPa. Our approach should be applicable to large-scale production of crystalline diamond-structured carbon.