Chemical vapour deposition concentration

An MWCNT has inner concentric tube(s) with smaller diameter(s) inside its hollow, and it is normally prepared in the carbon electrode of the arc-discharging method or by chemical vapour deposition method (see Chaps. 2 and 12). Influence of such inner tubes on the most outer layer in MWCNT is of interest with respect to electronic similarity of MWCNT and SWCNT. 

Diamond was doped by chemical vapour deposition to levels of 1019-1021/cm3. A bias was applied to achieve efficient extraction of the secondary B ions, and these were detected to map out the variation of B concentration from one area to another, as illustrated in Figure 4.7. 

The industrial application of Plasma Induced Chemical Vapour Deposition (PICVD) of amorphous and microcrystalline silicon films has led to extensive studies of gas phase and surface processes connected with the deposition process. We are investigating the time response of the concentration of species involved in the deposition process, namely SiH4, Si2H6, and H2 by relaxation mass spectroscopy and SiH2 by laser induced fluorescence. 

The reaction chamber is the heart of a CVD system where chemical vapour deposition takes place. It consists of retort, gas inlet injector, distributor and outlet exit. The quality of the deposit is mainly dependent on the design of the reaction chamber, which determines the uniformity of temperature, concentration and pressure. 

Young s modulus values of 2.7 GPa. Plasma-enhanced chemical vapour deposition (PECVD) was successfully used to produce a PMMA conformal coating (using methyl methacrylate monomers) on MWNTs. This increased the Young s modulus to 2.85 GPa at 3 wt% which corresponds to dT/dFf of 28.4 GPa. The overall set of mechanical properties indicates that the polymer coating had a significant effect on the mechanical properties at a 1 wt% concentration of tubes, suggesting improved interfacial adhesion between the filler and the matrix material. 

Figure 10.29. Turbidity of a 0.02 vol% suspension of sol-gel-derived 250 nm silica particles after 60 min in a solution of 0.1 MNaCl at pH 4 as a function of the C12TAB concentration, and the measured interaction forces between an AFM tip and the chemical vapour deposited (CVD) silica substrate under identical solution conditions. A significant repulsive force arises upon a change in concentration from 8 to 10 mM, which directly corresponds to the formation of a stable suspension (after ref. (10)). ( Reproduced with permission from Langmuir, 2000, 16, 7255-7262, Copyright (2000) American Chemical Society )...

The simplest composite fibres are the B and SiC monofilaments manufactured by chemical vapour deposition of boron halide or silane gases onto a heated substrate, normally W or C. Their diameter is in the range of 50-150 p.m, and they exhibit a concentric microstructure in which four different regions can be distinguished, the composition and thickness of each one depending on the actual fibre characteristics (Fig. 9). A thin (1-2 i.m) layer of pyrolytic graphite is deposited onto the C core before the deposition of... 

Fijf. 9. Cross-section of B and SiC composite monofilaments produced by chemical vapour deposition, showing the concentric core, interface, mantle and coating regions. 

The diffusion of F in silica at 1385 to 1873K was deduced from concentration profiles which had been measured using scanning electron microscopy of plasma-activated chemical vapour deposited samples. It was found that the data could be described by ... 

By developing aerosol vapour assisted chemical vapour deposition (AACVD) techniques, Blackman and coworkers have deposited gold nanoparticles on the surface of WO3 nanoneedles in a single step. This method involves a codeposition using a precursor solution, which is deposited on a substrate in the form of an aerosol. Control over the nucleation and growth kinetics is realised by careful consideration of the deposition temperature and reactant concentration. Again, the choice of... 

Vapour deposition processes present a certain potential with respect to their applicability to power plant components. This chapter concentrates on addressing the development of chemical vapour deposition (CVD) coatings on 9-12% ferritic-martensitic steels. Two processes have been investigated the in-situ CVD pack cementation process and the fluidised bed CVD (FBCVD) process. 

---