Nitrogen silicon nitrides

Another possibility is to replace by nitrogen. Silicon nitride has become an increasingly important industrial product. 

Pehlke, R. D., and J. F. Elliott High temperature thermodynamics of the silicon, nitrogen, silicon-nitride system. Trans. Met. Soc. AIME 215, 781-785 (1959). 

Zirconia, ZrOj, is made from the natural hydrated mineral, or from zircon, a silicate. Silicon carbide and silicon nitride are made by reacting silicon with carbon or nitrogen. Although the basic chemistry is very simple, the processes are complicated by the need for careful quality control, and the goal of producing fine (<1 jiva) powders which, almost always, lead to a better final product. 

Reactions (1), (2) and (3), which all use ammonia, have a tendency to deposit silicon nitride with a high ratio of included hydrogen, especially at the lower temperatures and if a plasma is used. This tendency is often detrimental but it can be remedied, at least to some degree, by using nitrogen instead of ammonia ... 

Schwier, G., On the Preparation of Fine Silicon Nitride Powders, inProgress in Nitrogen Ceramics, (F. Riley, ed.), pp. 156-157, MartinusNijhoff, Boston, MA (1983)... 

These polymers may be used in the preparation of quite pure silicon nitride if the pyrolysis is carried out in a stream of ammonia (a reactive gas) rather than under nitrogen or argon. The ammonia reacts with the... 

Heating silicon and nitrogen in an electric furnace produces a silicon nitride, Si3N4. 

Silicon nitride from silica, carbon and nitrogen, at about 1500°C. 

Current interest in saturated Si-N rings stems primarily from the industrial uses of silicon nitride (and related materials), which is a hard, chemically resistant insulator, and as precursors to silicon-nitrogen polymers (poly-silazanes). The formation and precursor chemistry of these polymers are discussed in Section 10.3.3. 

A less explored area of transition metal catalysis involves bond formation between Group 14 elements and nitrogen. In direct analogy to previously discussed areas of research, silicon-nitrogen bonds can be formed by dehydrocoupling, hydrosilylation, and dehydrogenative silylation. The compounds produced are valuable for use in organic synthesis or as polymer precursors to silicon nitride ceramics. 

The coupling of a trialkylsilane and an amine with loss of H2, catalyzed by palladium on carbon, was first reported by Sommer and Citron in 1967.178 More recent work by Laine and Blum has involved the application of catalytic dehydrocoupling of compounds containing Si-H and N-H bonds to form aligo- and polysilazanes. These polymers, with silicon-nitrogen bonds in the backbone, are useful precursors to silicon nitride. In the presence of Ru3(CO)i2, silicon-nitrogen bonds are cleaved and reformed... 

The Badische AniKn- und Soda-Fabrik prepared a nitride of undetermined composition by heating a mixture of silica and carbon in an atm. of nitrogen. The reaction proceeds at a relatively low temp, if a hydroxide or salt of a metal be added. The product contains silicon nitride mixed with the nitride of the metal. The Badische Anilin- und Soda-Fabrik also removed many of the impurities—iron, carbon, silicates, carbides, silicides, and phosphides—by treatment with acids or mild oxidizing agents which do not affect the silicon nitride. A. S. Larsen and O. J. Storm prepared the nitride by the action of nitrogen on molten silicides—e.g. ferrosilicon. 

Silicon Fluoride or Silicon Tetrafluoride. See in Vol 6, F146-R to F147-L, and G100-L under the history of NG manufacture where the use of SiF4 to separate the liq phases and recover the NG is Silicon Nitride. Si3N4 mw 140.31 grey-white amorph powd mp 1900 (sublimes) d 3.44g/cc. Sol in HF acid, Prepn is by reaction of powd Si and nitrogen in an electric furnace (Refs 1,37 ... 

In the following sections some examples are given of the ways in which these principles have been utilized. The first example is the use of these techniques for the low temperature preparation of oxide ceramics such as silica. This process can also be used to produce alumina, titanium oxide, or other metal oxides. The second example describes the conversion of organic polymers to carbon fiber, a process that was probably the inspiration for the later development of routes to a range of non-oxide ceramics. Following this are brief reviews of processes that lead to the formation of silicon carbide, silicon nitride, boron nitride, and aluminum nitride, plus an introduction to the synthesis of other ceramics such as phosphorus nitride, nitrogen-phosphorus-boron materials, and an example of a transition metal-containing ceramic material. 

All silicon nitride ceramics are derived from synthetic materials, exclusively. The first report on the synthesis of Si3N4 was in 1859 by Sainte-Claire Deville and Wohler [3]. Among the problems of greatest concern to chemists in those days was the utilisation of atmospheric nitrogen for agricultural and industrial purposes. In particular, there was a need for a highly effective... 

Thompson DP (1993) New Grain Boundary Phases for Nitrogen Ceramics. In Chen IW, Becher PF, Mitomo M, Petzow G, Yen TS (eds) Silicon Nitride Ceramics. Mat Res Soc Symp Proc 287 79... 

Gauckler LJ, Petzow G (1977) Representation of Multicomponent Silicon Nitride Based Systems. In Riley FL (ed) Nitrogen Ceramics, Noordhoff-Leyden, p 41... 

Riley FF (1983) Silicon Nitridation. In Riley FF (ed) Progress in Nitrogen Ceramics. Martinus Niihoff Publishers, Dordrecht, p 121... 

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