Silicon tetrachloride ammonia

The only disadvantage of the silicon tetrachloride-ammonia mctliod of generating smoke is its complication, and for this reason other simpler methods of smoke production were developed for field use. 

An important reaction for the deposition of silicon nitride combines silicon tetrachloride (SiCl4) and ammonia ... 

The reinforcing fibers are usually CVD SiC or modified aluminum oxide. A common matrix material is SiC deposited by chemical-vapor infiltration (CVI) (see Ch. 5). The CVD reaction is based on the decomposition of methyl-trichlorosilane at 1200°C. Densities approaching 90% are reported.b l Another common matrix material is Si3N4 which is deposited by isothermal CVI using the reaction of ammonia and silicon tetrachloride in hydrogen at 1100-1300°C and a total pressure of 5 torr.l" " ] The energy of fracture of such a composite is considerably higher than that of unreinforced hot-pressed silicon nitride. 

The "conventional" methods for the preparation of SiC and Si3N4, the high temperature reaction of fine grade sand and coke (with additions of sawdust and NaCl) in an electric furnace (the Acheson process) for the former and usually the direct nitridation of elemental silicon or the reaction of silicon tetrachloride with ammonia (in the gas phase or in solution) for the latter, do not involve soluble or fusible intermediates. For many applications of these materials this is not necessarily a disadvantage (e.g., for the application of SiC as an abrasive), but for some of the more recent desired applications soluble or fusible (i.e., proces-sable) intermediates are required. 

Zinc dust, hexachloroethane and aluminium Phosphorous pentoxide and phosphoric acid Sulfur, potassium nitrate and pitch Potassium chlorate, naphthalene and charcoal Zinc dust, hexachloroethane and naphthalene Silicon tetrachloride and ammonia vapour Auramine, potassium chlorate, baking soda and sulfur Auramine, lactose, potassium chlorate and chrysoidine Rhodamine red, potassium chlorate, antimony sulfide Rhodamine red, potassium chlorate, baking soda, sulfur Auramine, indigo, potassium chlorate and lactose Malachite green, potassium chlorate, antimony sulfide Indigo, potassium chlorate and lactose Methylene blue, potassium chlorate, antimony sulfide... 

Silicon nitride powder can be made by the reaction of silicon tetrachloride vapor with gaseous ammonia. The by-product is gaseous hydrogen chloride. Write a balanced equation for the reaction. 

Uses For producing screening smokes (British attack on Zeebrugge). In combination with ammonia vapor it forms smokes which resemble natural fog and which are effective for camouflaging troop or ship movements. The smoke is generated from a smoke funnel. One cylinder contains liquid ammonia the other cylinder is charged with silicon tetrachloride containing about 10 per cent carbon dioxide under a maximum pressnre of 550 lb/sq. in. at 55°. 

Other established routes to silicon nitride involve silicon sulfide intermediates (equations 5a and 5b) (8, 9), the reaction of silane with ammonia (equation 6) (10), or the reactions of various chlorosilanes such as silicon tetrachloride with ammonia (equations 7-8) (11-17) ... 

The t omplications involved in producing dense smoko by use of ammonia with silicon tetrachloride caused the introduction of titanium tetrachloride by the Allies, near the end of tbe war, as a sulietHute for lin and mlicon tetrachlorides. 

Silicon tetrachloride also reacts with ammonia in the vapour phase at 825 to give chlorosilazanes of low molecular weight such as ... 

Some ceramic materials are not found widely or at all in nature, and thus are synthesized for use. To prepare more complex ceramic compositions such as perovskites of general structural formula ABO3, and ferrites, of formula MFc204, the individual oxides or salts of the cations A, B, and M are often combined as powders and then reacted at high temperature by a solid-state diffusion mechanism. Silicon nitride (Si3N4) can be manufactured from either the nitridation of silicon metal or from the reaction of silicon tetrachloride with ammonia. Silicon carbide (SiC) is obtained from the reduction of silica with a carbon containing source. 

Dichlorosilicon phthalocyanine (XIX) is prepared from silicon tetrachloride and phthalonitrile in quinoline at 200°C 168,170). The blue-green crystals, which sublime readily at 430°C in vacuo, hydrolyze forming dihydroxysilicon phthalocyanine (XX) when refluxed with equal volumes of pyridine and aqueous ammonia (200). The corresponding difluorosilicon phthalocyanine is resistant to hydrolysis. Conversion of the chloride to the corresponding dicyanate, dithiocyanate, and diselenocyanate occurs upon reaction with the appropriate silver pseudohalide (178). The complexes are believed to involve nitrogen to silicon bonding in the case of the thiocyanate and selenocyanate. 

During the reaction of silicon tetrachloride with liquid ammonia, the intermediate, Si(NH2)4 was presumed. A precipitation of different polymeric products [e.g., the diimid, Si(NH)2] subsequently occurs, which finally yields silicon nitride. This reaction involves a multiple-step mechanism. Simplified chemical reactions are shown in Eqs. (9) to (11) (for a more detailed description, see, e.g.. Refs. 37-40). 

It is possible to produce submicron particles of a-Si3N4 by reacting silicon tetrachloride, a liquid at room temperature, and ammonia. The reaction involves the formation of silicon diimide [Si(NH)2] as an intermediate phase. 

Silicon nitride is usually deposited using one of the following silicon precursors silane, dichlorosilane, trichlorosilane, or silicon tetrachloride. Silicon tetrachloride, the most common silicon precursor, is used with an ammonia and nitrogen mixture to obtain silieon nitride at temperatures of 800 to 1,400X (1,472 to 2,552 F). Silicon carbide is usually produeed by cracking methyl trichlorosilane at 800 to 1,400°C (1,472 to 2,552 F). 

DisiUcon hexabromide, hexabromodisUane, forms well-crystallized white plates or prisms (m.p. 95°, b.p. 265°). It is soluble in a variety of organic solvents, such as carbon tetrachloride, chloroform, carbon disulfide, and benzene, as well as in silicon tetrachloride or tetrabi omide. It is rapidly hydrolyzed by the moisture of the air, forming insoluble "silicooxalic acid, (H2Si204)x and with solutions of ammonia or of strong bases it forms sihcic acid or silicates, with liberation of hydrogen. 

Silicon nitride (Si3N4) is a major industrial material which is produced extensively by CVD for electronic and structural applications. It is an excellent electrical insulator and diffusion barrier (to sodium and water vapor) and has replaced CVD oxides in many semiconductor devices.l l Silicon nitride coatings are produced by the reaction of silicon tetrachloride (SiCl4) with ammonia ... 

For example, the diimide process involves the reaction of silicon tetrachloride or organyl aminosilane with ammonia and the subsequent thermal decomposition of the siUcon diimide according to ... 

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