Preparation And Properties Of Al2O3/Tic/CNTs Composites

Because of its excellent conductivity, mechanical properties, thermal properties and other excellent properties, Carbon nanotubes has obtained the widespread application in electrochemical device, hydrogen storage, a field emission device, sensor, modified electrode, adsorption materials, catalyst carrier and has also been widespread concern currently in preparation of structural ceramics, functional ceramics and structure/function integration composite ceramic material. Al2O3/TiC composite ceramic material is commonly used in engineering structure ceramic material, but the crack sensitivity, is a kind of brittle material and is extremely easy to cause the surface cracks or cracks, even surface peeling or shed off the machine processing and the use of the process, leading to the mechanical properties of the material greatly reduced and limiting its scope of application. Carbon nanotubes as inorganic fiber reinforced material with light weight, high strength, toughness and elastic modulus, resistance to acid and alkali resistance, therefore the research of carbon nanotubes nanoAl2O3TiC ceramic composite material has a certain theoretical and practical significance.Al2O3/TiC/CNTs bulk composites are obtained by hot pressed sintering. Preparation process and mechanical properties of Al2O3/TiC/CNTs composites are investigated, optimization of process parameters affecting the sintering and optimum process conditions to be determined. Micro structure and fracture morphology are analyzed by XRD and SEM. We preliminarily discuss the strengthening and toughening mechanism of Al2O3/TiC/CNTS composite. Uniformly dispersed nanoscale Al2O3/TiC/CNTs composite powder is prepared By mechanical ball milling method and multiple phase suspension. The powder surface morphology is observed by SEM show that the carbon nanotubes is dispersed in the form o(?) bridging and the particle size distribution is more uniform due to short time of mechanica milling, almost no damage to the carbon nanotubes.The main factors affecting the mechanical properties of Al2O3/TiC/CNTs composites (ATC for short) are analyzed and the best mechanical prperties increased by 14.40% anc 10.63% repectively compared with Al2O3/TiC composites in the bending strength and the fracture toughness are determined—hardness HRA 91.2, bending strength 556.19Mpa, fracture toughness 4.89 Mpa.m1/2, Corresponding to the optimum parameters for CNTs content 1wt.%, sintering temperature 1650℃,hot pressure 35Mpa and holding time 30min The mechanical properties of ATC composites prepared by ethanol are superior to that prepared by Surfactant method.The fracture morphology of ATC composites is observed by SEM and the resul(1) obtained shows that fracture mode of ATC composites compared with that of AT composite is changed, is mixed transgranular and intergranular fracture, but still mainly intergranulai fracture. The strengthening and toughening of ATC composites is mainly from crack deflection and crack bifurcation with carbon nanotubes bridging and pull-out mechanism Both carbon nanotubes play a role in weakening the interface, but also play the role of crack bridging, effectively prevent the crack growth.Single-cycle thermal shock and thermal shock are tested by Chill-intensity method. The research shows that compared with AT composites, thermal shock resistance of ATC composites have been significantly improved. Thermal shock theory analysis shows that the thermal shock resistance of ATC composites is higher than that of AT composites, which is consistent with the experimental results, because of the high ratio of fracture toughness to bending strength and high bending strength.