SiC, processing

For a CVD SiC process from a CH3SiCl3-H2 reaction system, two kinds of reactors were reported by Brennfleck and Reich in 1993 [36], as shown in Figure 3.12. The retort of the horizontal reactor has a diameter of 550 mm and a length of 1500 mm, while the vertical reactor is comparatively larger, the diameter and the... 

This pyrocarbon layer has a high density ranging from 1.85 to 2.0 g-cin 3 and its thickness is 40 10 p,m. It can not only protect the outer SiC layer from detrimenta reactions but also protect the buffer layer and the U02 kernel from chlorine intmsion during the CVD SiC process with CH3SiCl3 as the reactant gas. 

HC1 has a bonding energy of 432 kJ-mol1, hence it is very difficult to decompose into H and Cl radicals. Nevertheless, absorption between H on C surface atoms and Cl and Si is very easy. This causes competition of absorption to Si by CH3 and Cl radicals. Similarly, SiCl3 and H radicals compete for absorption to C. The inhibition effect of HC1 on the deposition of a CVD (3-SiC process was confirmed by experimental studies [40],... 

V.A.lzhevskyi, L.A.Genova,A.H.ABressiani, J.C.Bressiani Liquid phase sintered SiC processing and Transformation controlled microstructure tailoring. Material research, 2000,3[4]131-138... 

FIGURE 24.3 SiC processed with addition of AI2O3 at 2050°C etched polished surface. 

V.A. Izhevskyi, L.A. Genova, A.H.A. Bressiani, and J.C. Bressiani, Liquid Phase Sintered SiC. Processing and Transformation Controlled Microstructure Tailoring, MatRes., 3(4), 131-38 (2000). V.A. Lavrenko, D.J. Baxter, A.D. Panasyuk, and M. Desmanion-Brut, High-Temperature Corrosion of AIN-Based Composite Ceramic in Air and in Combustion Products of Commercial Fuel. 1. Corrosion of Ceramic Composites in the AIN-SiC System in Air and in Combustion Products of Kerosene and Diesel Fuel, Powder Metallurgy and Meta Ceramics, 43(3-4), 179-86 (2004). 

The appHcabiHty of many of the government regulations are based on the Standard Industrial Classification (SIC) of the process and/or faciHty. 

New Materials Technology. The unique chemical compatibihty of Si02 with sihcon and aluminum has been a significant factor in the dominance of siUcon-based semiconductor technology for MOSFETs in particular and integrated circuits in general. Two enhancements of conventional bipolar or MOS processes have been studied siUcon on insulator (SOI) and SiGe. An alternative material of importance is SiC. 

The silicon carbide, produced in the middle zone of the furnace, is pushed down by stoking and reacts with Si02 to produce silicon. The silicon produced is periodically or continuously tapped. Rising SiO reacts with the carbon in the bed and is converted to SiC and the process repeats itself. 

In one modification of this procedure, the starting material is pyroly2ed rice hulls in place of more conventional forms of sihcon dioxide (31). Another unique process involves chlorination of a combination of SiC and Si02 with carbon in a fluid-bed reactor (32). The advantages of this process are that it is less energy-intensive and substantially free of lower sihcon chlorides. 

The ceramic, polycrystalline siHcon carbide [409-21-2], SiC, is processed using P-siHcon carbide and boron (9). The boron is a sintering aid used at... 

The hydrocarbon is carried in a stream of H2 or Ar, and P-SiC is formed or P-SiC is formed by reaction in the gas phase, under static conditions, of compounds such as SiO or CO formed in situ during the process. In this latter case the important reaction appears to be SiO + 3CO — SiC + 2CO2. This... 

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). 

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