Carbon films useful properties

Polysiloxane based block copolymers have also been examined with respect to their transport properties, because these copolymers are of special interest as membranes in various biomedical applications 376). The combination of good mechanical, dielectric, permeation and film formation properties of siloxane-carbonate segmented copolymers have led to their use as blood oxygenation, dialysis and microelectrode membranes 392 394. ... 

The structure of a-C H films may be thus pictured as sp--carbon atoms in condensed aromatic clusters, dispersed in an sp- -rich matrix, which confers to the network its characteristic rigidity. This situation can also be regarded as a random covalent network in which the sp" clusters of a defined size take part in the structure as an individual composed atom with its corresponding coordination number [17]. Such kinds of models have been successfully used to describe the dependence of a-C H film mechanical properties on composition, hybridization, and sp" clustering [23]. 

Plasma Synthesis The use of plasma methods has lead to a new range of materials having unique properties. An example is the family of amorphous elemental hydrides (eg cr-C H Of -Si H or-P H) which contain a variable proportion of H from almost zero to 50 atomic %. The carbon films, known variously as "hard carbon", "diamond-like carbon", " a-carbon" etc (9 ) - These layers are of considerable interest because of their optical and abrasion-resistant properties etc (Table I). The properties of these Gr-carbon films, can be tailored by modifying the plasma parameters. 

The synthesis and electrochemical properties of carbon films prepared from positive photoresist have been reported.The initial direction for this work was the fabrication of carbon interdigitated electrodes. In this work, positive photoresist was spin coated on a silicon substrate, patterned by photolithography, and pyrolyzed to form the carbon electrode. In more recent work, laser excitation has been used to both pyrolyze the film and to write the electrode pattern. ... 

It is likely that we will see increasingly numerous examples of such systems in applications as diverse as home clinical chemistry assay kits and remote sampling for environmental applications. The discussion here outlines general applications and some of the unique physical properties and fabrication considerations of film electrodes, and then focuses in greater detail on preparation and properties of widely used examples of metallic, carbon film, and semiconductor electrode materials. 

In Section 2 we showed that the properties of amorphous carbon vary over a wide range. Graphite-like thin films are similar to other carbonaceous materials (glassy carbon, and the like) in their electrode behavior. Redox reactions proceed in a quasi-irreversible regime on these films. In particular, the cathodic reduction of nitrate previously studied on crystalline diamond electrodes (see Section 6.4.2) was performed with amorphous carbon films prepared by UHV laser deposition and comprising both sp2- and sp3-carbon [152], Reduction current density as high as 2 mA cur 2 was reached in neutral or alkaline solutions. The use of such electrodes in microgravimetry is discussed [153]. 

In the majority of cases nanoporous materials exist in a highly dispersed state (seldom - as films). It limits practical application of these materials and in many cases makes difficult for study of their properties. Samples of the nanoporous carbon (NPC) used in this work are produced as a body of cylinder shape with a sufficient mechanical strength. They synthesized by heat treatment of carbide silicon and carbide titanium in chlorine have been studied in the present work. The samples of materials are characterized by the advanced structure of pores, which contains two types of pores macropores (with the sizes in a few micron) and nanopores with sizes about 0.8 nm. Surface area and volume of pores NPC with... 

Diamond-like carbon since its inception in 1962 has found applications in some very important areas. These applications include coatings used in scratch-resistant optics, razor blades, prosthesis in medical applications electron emission surfaces in electronics as an insulator material for copper heat sinks in semiconductors such as solar cells and sensors for visible to infrared radiations and as structural materials such as deuterated DLC film used for neutron storage in advanced research instrumentation. As technology matures the unique properties of DLC will find new and important applications. 

Ceramic coatings on fibers and powders have a variety of uses. For example, porous ceramic coatings on nanoscale metallic or ceramic particles can improve the catalytic properties of a powder. Also, the carbon fibers used as reinforcement in metallic matrices can be coated with a thin ceramic film (such as SiC or TiN) to reduce the rate of interdiffusion that may occur between the matrix materials and the fibers, and enhance the wetting of the fiber surface by metals. ... 

Q.F. Huang, S.F. Yoon, Rush, Q. Zhang and J. Ahn, Dielectric Properties of Molybdenum-containing Diamond-like Carbon Films Deposited Using Electron Cyclotron Resonance Chemical Vapor Deposition, Thin Solid Films, 409, 211-219 (2002). 

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