| Ceramic foams have been widely used in catalyst carriers, hot gas collectors, molten metal filters, thermal insulators, bio-ceramics, chemical sensors and separation membranes because they have unique three-dimensional skeleton structure, high porosity, low density, high thermal stability and resistance to chemical attack. If the pores can be orderly arrayed with reverse opal structure, porous ceramic will have a lot of unique advantages such as selective filtration and separation, good permeability and high mechanical properties. The increasing interest in epoxy resin has been associated mainly with their specific properties, such as excellent mechanical and adhesive properties, high electronic insulation and good chemical resistance. These characteristics make epoxy resin useful in an array of applications including protective coatings, paints, adhesives, electronics encapsulation and various cast products. Recently, with the expected improvement in properties from the incorporation of fillers into epoxy resin, research into epoxy composites has become a fast expanding field.Porous Al2O3 and Al2O3-ZrO2 ceramics with dense cell struts and ordered pore structure were fabricated by a novel process which can be described as forming a close-packed template with plant seeds (millet) or epispastic polystyrene spheres, filling the interstitial spaces with ceramic slurries by centrifugal slip casting, and removing the template to obtain a porous inverse replica. This novel process has the particular advantage that defects (holes and cracks) that often exist in the cell struts for the commonly used organic sponge pyrolysis method can be avoided, inducing homogenous and dense cell struts and good mechanical properties of sintered products. In this paper, preparation process of Al2O3 and Al2O3-ZrO2 slurries, segregation phenomenon in mono-phase and multi-phase systems during centrifugal slip casting and effect of centrifugal experimental parameters on properties of green compacts and sintered products were studied. A BP neural network model for predicting compressive strength of porous Al2O3-ZrO2 ceramics was built. 3D interpenetrated Al2O3/epoxy composites were fabricated using the ordered porous Al2O3 ceramics as the frame. Mechanical properties, high temperature dimension stability and friction characteristics of the composites were investigated.In the process of fabricating porous Al2O3 ceramic, highly dispersed and stable Al2O3 suspensions with 50vol% solid content were prepared by adjusting pH values and the amount of the dispersant. In the shear rate range of 10～180 s-1, the slurry has shear thinning characteristic, with a rheological model expressed asη= 3.451+967.9295γ-0.415. No obvious mass segregation due to sedimentation difference of the initial Al2O3 particles was observed in the slurry with 50 vol% solid loading because of its good fluidity and stability The cell wall of green compacts centrifuged at acceleration of 2860 g has high and uniform density of 63.4 %. After sintering at 1500℃, a reverse opal structured Al2O3 porous ceramic with uniform and high wall density (98.9 %TD) and ordered pore array was produced. SEM observation showed that the Al2O3 grains distribute homogeneously in both the top and the bottom of the sintered products. When changing the load applied on the EPS templates from 7.3 N to 19.6 N, porosity of the porous Al2O3 ceramics increased from 71.8% to 83.2% and the compressive strength decreased from 3.85 MPa to 1.78 MPa. The porous alumina ceramics can resist 6-8 times repeated thermal shock from 1100℃to room temperature. Choosing millet as the templates, the porosity and compressive strength of the porous Al2O3 ceramics are 66.5% and 5.06 MPa, respectively, and the porous ceramics can resist 5 repeated thermal shock from 1100℃to room temperature.In the process of fabricating porous Al2O3-ZrO2 ceramic, highly dispersed and stable Al2O3-ZrO2 slurries with 50vol% solid content were prepared by adjusting pH values and the amount of the dispersant. In the shear rate range of 10～180 s-1, the slurry of Al2O3-ZrO2 has a shear thinning characteristic and its rheological model can be expressed asη= 3.451+967.9295γ-0.415. Mass and phase segregation due to the sedimentation difference of Al2O3 and ZrO2 particles was hindered in the slurries with 50 vol% solid loading. The cell wall of green compacts centrifuged at acceleration of 2860 g had high and uniform density of 61.5%. After sintering at 1550℃, a reverse opal structured Al2O3-ZrO2 porous ceramic with high and uniform wall density (99.1 %TD) and homogenous ZrO2 particle distribution at both the top and the bottom was produced. When changing the load applied on the EPS spheres from 7.3 N to 19.6 N during packing, the porosity of the porous Al2O3-ZrO2 ceramics increased from 71.5% to 83% and the compressive strength decreased from 4.51 MPa to 2.07 MPa. The Al2O3-ZrO2 porous ceramic can resist 8-11 times repeated thermal shock from 1100℃to room temperature.A BP neural network model for predicting the compressive strength of porous Al2O3-ZrO2 ceramic was built by the gradient descent arithmetic with momentum and adaptive learning rate. The model is high in learning rate and accuracy and the predicted results agree with the actual data within reasonable experimental error. The BP neural network method is superiors in predicting materials properties with less experimental data and high efficiency and preciseness. 3D interpenetrated Al2O3/epoxy composites were fabricated using the ordered Al2O3 porous ceramic as the frame. Compared with epoxy resin and Al2O3-particle/epoxy composites, the 3D interpenetrated Al2O3/epoxy composites have better room temperature and high temperature mechanical properties. At room temperature, flexural strength, flexural modulus, compressive strength and compressive modulus of the composite are 116 MPa,3.6 GPa,170 MPa and 2.4 GPa, respectively. The composites have good dimensional stability at high temperature and no deformation can be observed at 180℃. Its compressive strength and modulus are 48 MPa and 0.9 GPa, respectively at 120℃. The new composites have good wear resistance, low friction coefficient and wear mass loss. The composites have stable friction coefficient with the change of load, sliding velocity and sliding time.
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