Silicon nitride powder was milled in toluene in the presence of silanes which can react with surface OH groups. This procedure allows a stable immobilisation of modifying groups on surfaces of silicon nitride powder. Due to the modification procedure used and supported by quantitative measurements, the surface can be regarded asconsidered to be covered by a monolayer of covalently bound modifying groups. The modified powders were further characterized by FT-IR spectroscopy and by their suspension-sedimentation behavior. Batches prepared from this new type of powder can be easily transformed to granules which were densified to green compacts. The experiments indicate, that powder modification has a stronger impact on the green density than binder variation. Best results are obtained with a trimethylsilyl-modified powder. This powder has a hydrophobic surface. Here the surface polarity and therefore thus the powder/powder interactions are reduced. Non-modified Si{sub}3N{sub}4 and other polar powders (e.g. aminoalkyl-modified powders) result in similar but lower green densities.
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