Reduction Annealing Synthesis of Nanostructured Carbide and Nitride Particulate Composites

Sammanfattning: This thesis covers reduction-annealing synthesis of nanostructured SiC-TiCN and SiC-TiC particulate composite powders. These were characterized by X-ray diffraction and electron microscopy. In the SiC-TiC powder it was found that TiC could be added in certain amounts by reducing controlled amounts of titanium chloride source followed by a suitable annealing. A transmission electron microscopy showed that TiC formed polyhedrons and SiC formed rods. This was in agreement with a trend towards these crystal shapes, regardless of synthesis method, as found in the literature. In the SiC-TiCN particulate powder, nitration was achieved at low nitrogen concentration. In a scanning electron microscopy study it was seen that SiC formed elongated crystals, while TiCN formed polyhedrons. A gradual nitration of TiC into TiCN was proposed. Nitration was promoted by a high reactivity of TiC and an integrated nitrogen surplus over titanium and carbon amount during annealing.