Study On Cordierite Honeycomb Ceramic Substrate

Honeycomb ceramics are used as substrates for automotive exhaust catalysts and ozone abatement catalysts. They are also can be used for heat exchange and molten metal filtering. Cordierite was chosen for making Honeycomb ceramics because this compound has low thermal expansion, relatively high melting point and high mechanical strength. This thesis described the performance of the honeycomb ceramics, studied mainly the process for manufacturing cordierite honeycomb ceramics using rectorite, talc and A12O3. Plasticity index, green body strength, fired strength and coefficient of thermal expansion (CTE) were tested to decide the best ingredient. All the sintered cordierite honeycomb ceramics had been characterized by bulk density(D), water absorption(Wa), apparent porosity(Pa),mean pore size and CTE. The phases composition of the honeycomb ceramics were tested by XRD method and the microstructure was tested by SEM method. The results show that as follow.1. The rectorite is a kind of clay which has high plasticity and binding capacity. High plasticity raw batch without any additive were manufactured for extruding. Its plasticity index is 4.55 kg cm with 35-38wt% of water.2. The best scheme: The raw meal to the cordierite grog is 7:3.3. The best process group of forming additive in the all raw meal was: 40wt% of water, 6wt% of glycerol, 10wt% of dextrin. The best process group of forming additive in the mixture of 7:3 was: 40wt% of water, 10wt% of glycerol, 10wt% of dextrin.4. Forming process was: The vacuum was 0.09MPa, and kept 2min when the pressure was 5MPa. The highest forming pressure was 20Mpa.5.The best drying process: 50℃2h,70℃2h,80℃2h,90℃2h,100℃ until the water absorption was less than 1% in oven.6. The best sintered temperature of the extruded honeycomb ceramics was 1220 and the soaking time was 2h at this temperature.7. The CTE was concerned with the ratio of the raw meal to the grog. The CTE increased in a ratio with the content of the grog..8. The CTE(25-1000℃) of the honeycomb ceramics made from all raw batch was 1.909X 10-6℃. The CTE(25-1000℃) of the 7:3 was 3.325x10-6℃.9. The Wa, Pa, D and mean pore size of the honeycomb ceramics made of all raw batch were 24.4%, 12.9%, 1.88g/cm3 and 83jam separately, and the same of the 7:3 were 34.9%, 19.9%, 1.75 g/cm3 and 51um separately.10. Thermal shock resistance of honeycomb ceramics was 600℃.