Processing methods chemical vapor deposition

Typical processing methods - chemical vapor deposition polymerization electrospinning spin coating ... 

Carbon Composites. In this class of materials, carbon or graphite fibers are embedded in a carbon or graphite matrix. The matrix can be formed by two methods chemical vapor deposition (CVD) and coking. In the case of chemical vapor deposition (see Film deposition techniques) a hydrocarbon gas is introduced into a reaction chamber in which carbon formed from the decomposition of the gas condenses on the surface of carbon fibers. An alternative method is to mold a carbon fiber—resin mixture into shape and coke the resin precursor at high temperatures and then foUow with CVD. In both methods the process has to be repeated until a desired density is obtained. 

Process of chemical vapor deposition (CVD) is one of the most effective methods for preparation of flat emission cathodes. This method allows to produce different carbon structures on the cathode substrate. Depending on conditions of deposition, derivable carbon surface can be diamond-like films [1], amorphous graphite [2], various carbon constitutions, including carbon nanotubes [3], Investigation results of field emission properties produced cathodes have shown this is a promising technology for production Field Emission Display (FED). 

Specific physicochemical properties of the supercritical fluids offer flexible alternatives to established processes like chemical vapor deposition (CVD), which is used in the preparation of high-quality metal and semiconductor thin films on solid surfaces. Watkins et al. [43] reported a method named chemical fluid deposition (CFD) for the deposition of CVD-quality platinum metal films on silicon wafers and polymer substrates. The process proceeds through hydrogenolysis of dimethyl-(cyclooctadiene)platinum(ll) at 353 K and 155 bar. 

Chemical vapor impregnation (CVl) is a method of infiltrating fiber architectures with matrix particles via the vapor phase. Although this is a similar process to chemical vapor deposition (CVD) in terms of gas reaction, decomposition conditions in CVl are chosen for in-depth decomposition rather than coating the surface of the substrate. 

The methods employed in the deposition of thin films of oxides can be divided into two major groups based on the nature of the deposition processes. Physical methods of deposition physical vapor deposition (PVD) (Kueir-Weei et al., 1997), ion beam (Xiaodong et al., 2008) and sputtering (Haiqian et al., 2010). The chemical methods of deposition, which can be subdivided as to the nature of the precursor gas phase and solution. The gas phase methods chemical vapor deposition (CVD) (Bryant, 1977) and atomic layer epitaxy (ALE) (Suntola, 1992). The solution methods spray pyrolysis (Chamberlin Skarman, 1%6), sol-gel (Brinker et al., 1990) and electrodeposition. 

Sihcon carbide is also a prime candidate material for high temperature fibers (qv). These fibers are produced by three main approaches polymer pyrolysis, chemical vapor deposition (CVD), and sintering. Whereas fiber from the former two approaches are already available as commercial products, the sintered SiC fiber is still under development. Because of its relatively simple process, the sintered a-SiC fiber approach offers the potential of high performance and extreme temperature stabiUty at a relatively low cost. A comparison of the manufacturing methods and properties of various SiC fibers is presented in Table 4 (121,122). 

Up to the present, a number of conventional film preparation methods like PVD, CVD, electro-chemical deposition, etc., have been reported to be used in synthesis of CNx films. Muhl et al. [57] reviewed the works performed worldwide, before the year 1998, on the methods and results of preparing carbon nitride hlms. They divided the preparation techniques into several sections including atmospheric-pressure chemical processes, ion-beam deposition, laser techniques, chemical vapor deposition, and reactive sputtering [57]. The methods used in succeeding research work basically did not... 

Metal and polysilicon films are formed by a chemical-vapor deposition process using organometallic gases that react at the surface of the IC structure. Various metal silicide films may also be deposited in this manner by reaction with the surface of the silicon wafer to form metal silicides. Glass and pol3uner films are deposited or spin cast or both, as are photoresist films (those of a photosensitive material). This process is accomplished by applying a liquid polymer onto a rapidly rotating wafer. The exact method used varies from manufacturer to manufacturer and usually remains proprietary. 

For this purpose, all three catalyst supports were initially synthesized by a chemical vapor deposition (CVD) process and thereafter, using a wet impregnation method, loaded with cobalt as the active component for FTS. The as-synthesized Co/nanocatalysts were then characterized by applying electron microscopic analysis as well as temperature-programmed desorption, chemi- and physisorption measurements, thermogravimetric analysis, and inductively coupled plasma... 

Films at NASA GRC were deposited using homemade spray or aerosol-assisted chemical vapor deposition (AACVD) reactors to exploit the lower deposition temperature enabled by the simpler decomposition chemistry for the SSPs.6 9 AACVD is a simple and inexpensive process that offers the advantage of a uniform, large-area deposition, just like metal organic CVD (MOCVD), while also offering the low-temperature solution reservoir typical of spray pyrolysis methods. 

YDC has been prepared by various methods, including solid-state reaction, coprecipitation, glycine-nitrate process and metal organic chemical vapor deposition (MOCVD). Table 1.4 shows that the properties depend on the preparation method [118,119,127,129,130], Zha et al. [129] have studied the influence of sintering... 

Over the past few years, a large number of experimental approaches have been successfully used as routes to synthesize nanorods or nanowires based on titania, such as combining sol-gel processing with electrophoretic deposition,152 spin-on process,153 sol-gel template method,154-157 metalorganic chemical vapor deposition,158-159 anodic oxidative hydrolysis,160 sonochemical synthesis,161 inverse microemulsion method,162 molten salt-assisted and pyrolysis routes163 and hydrothermal synthesis.163-171 We will discuss more in detail the latter preparation, because the advantage of this technique is that nanorods can be obtained in relatively large amounts. 

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