Residue fine-grained

Sihcon nitride occurs in two forms, a-Si N and P-Si N. Pure Si N is white, but the colors of commercial materials may be tan, gray, or black because of residual siUcon or impurities. Si N may be prepared by nitriding siUcon powder at 1200—1400°C or, for extremely fine-grained Si N, by the reaction of SiCl or SiH and N2 or NH (see also Advanced ceramics). 

Ideally the product is a fine-grained ceramic containing interlocking crystals with sizes ranging from less than 10 nm in transparent glass-ceramics to several micrometres, with a residual, usually small, glass content. The behaviour of the material is largely determined by the choice of the cry-... 

Abstract A tailings pond for dumping the fine grained residues of the tin ore processing... 

Cleanup strategies for hydrocarbon-affected soil will most likely be the last issue to be mandated from a regulatory perspective and certainly the most difficult technically to address. This difficulty reflects the large, deep-seated volumes of residual hydrocarbon present, and the current lack of efficient, cost-effective methodologies for in situ remediation of residual hydrocarbons in low-permeability, fine-grained soils. 

Figure 1.52 Micro structure of a typical glass ceramic with a fine grain size, minimal residual glass, and little porosity (P). From W. E. Lee and W. M. Rainforth, Ceramic Microstructures. p. 59 Copyright 1994 by William E. Lee and W. Mark Rainforth, with kind permission of Kluwer Academic Publishers.

Precipitate A fine-grained insoluble substance that is formed when two clear solutions react together to form an insoluble material that slowly falls out of solution as a residue. 

SEM photographs of the surfaces of the sintered samples are shown in Fig. 4 (A). The surface microstructure reveals uniform and fine grain growth about 2-3 pm. No pores were observed on the surface of the sample, but there were some pores from the fracture surface of the sample, as shown in Fig. 4 (C). The sintered density is 6.6 g/cm, which is over 95% of the theoretical value. The residual pores may be partly attributed to the agglomerates in the source powders that lowered the sinterability of the green bodies. It can also be seen that there are no great changes between the pellets sintered in air before and after heat treatment at 750°C for 5h in H2. This result is in aecordance with that of XRD. It confirms that the samples are chemically stable in H2 atmosphere at least below 750°C. 

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