PREPARATION AND PROCESSING OF METAL CERAMIC COMPOSITE-MATERIALS

The preparation of nanometer-sized Ni particles in a SiO2 matrix by a three-step procedure is reported. In the first step, metal-organic Ni compounds are dissolved in water and reacted with the ethylenediamine derivative H2NCH2CH2NH(CH2)3Si(OEt), (Et = -CH2CH3). During this reaction, ammonia-catalysed hydrolysis and condensation of the alkoxy groups take place. After the removal of the solvent, the resulting gel is dried and pyrolysed under oxidation conditions in the second step. The last step involves the reduction of the NiO/SiO2 composite material in pure hydrogen. The as-prepared product contains homogeneously dispersed Ni particles in the SiO2 matrix. Depending on the metal loading, the oxidation and reduction conditions, and on the further heat treatment the particle size distribution can be varied in a wide range.