Investigations On The Process Of Al₂O₃-TiCN-Fe Composites With Low Cost

Composites are developing very fast in recent years and widely used in manyaspects in different fields of the industry. Cermet, a model of composite, has the goodmechanical properties in high temperature resistance, high strength and antioxidation;and it is also combined with the plasticity of metals and represents the performance ofcomprehensive mechanics. Al₂O₃-TiC matix ceramic is becoming a hot spot of theresearch on composites, but it has low toughness. To improve the toughness of thecermet, researchers make more progress by adding ductile metal, such as Co, Ni or Mo,to the Al₂O₃-TiC matix ceramic to prepare the Al₂O₃-TiC-Me composites. But their costis too high. A lot of researchers are trying to use Fe, a lower cost ductile metal, toreplace the traditional metals and to prepare Al₂O₃-TiC-Fe composites, which workswell. However, the preparation is very complex. Compared with TiC, TiCN shows goodphysical and chemical properties. Al₂O₃-TiCN matrix ceramic composites have a betterapplication prospect than Al₂O₃-TiC matrix ceramic composites.In the present work, Al₂O₃-TiCN-Fe composites are prepared by in-situ reactionduring hot pressing sintering, utilizing the thermit reaction and carbothermic reactionbetween ilmenite and graphite, aluminum in N2atmosphere, and the cost of the processis very low. A systematic research has been carried out to investigate the effects of ballmilling process and sintering process on the microstructure and mechanical properties.In the following investigation, we take good advantage of the ilmenite, which is a richresource in our country. Fe and Ti elements, Al₂O₃existed in the ilmenite are fullyutilized. The composites are prepared by in-situ reaction technology by which they havegood properties. This low-cost process is easy to control. This investigation establishesa foundation for the basic research of the preparation and application of cermet.Themain results are as follows:①Well-distrbuted degree of the size of the wet-milling powders is better than thatof the dry-milling powders, but the average particle size of the wet-milling powders isbigger than that of dry-milling powders. And the raw materials do not react during theball milling, but the carbon of dry-milling powders becomes amorphous.②After the sintering, there are less pores in the wet-milling powder than that inthe dry-milling powder. When the sintering pressure of20MPa,the sintering temperatureof1400℃and holding time of30min are used, the bending strength of sintered samples after wet-milling is303MPa,while that after dry-milling is only217MPa. Thesintered samples after wet-milling shows a little higher of hardness and density③As to dry-milled powder, optimized sintering parameters are obtained. When thesintering pressure of30MPa, the preset pressure of15MPa, the sintering temperature of1500℃and the holding time of30min are used, the composites shows better properties.And the bending strength is305MPa, Vickers-hardness is16.11GPa and the density is4.624g·cm^-3；④As to wet-milled powder, optimized sintering parameter are obtained. When thesintering pressure of30MPa, the preset pressure of15MPa, the sintering temperature of1450℃and the holding time of30min are used, the composites shows better properties.And the bending strength is422MPa, Vickers-hardness is17.50GPa and the density is4.503g·cm^-3；...