| Foam ceramics, with particular structure of3D open porosity and excellent texture properties, have showed great superiority in the field of molten metal filtration. Organic sponge impregnation technology, due to its simple process and low cost, is an economical and practical method for ceramic foam appliance. Presently, the main technical problems for ceramic foam lie in its low Mechanical properties, poor thermal shock resistance and long-term stability.All these restrain the application for the ceramic foam, and therefore having become the hot spots of ceramic foam research.Ceramic foam mechanical properties and thermal shock resistance is often made by the preparation method decision.The rheological properties and stability of slurry is investigated by testing the ZrO2-Al2O3suspension system of surface zeta potential, settlement and viscosity。This paper expatiated the effect of low temperature binder and two dispersant (PAA-NH4、 silica sol) content and pH value for the property of foam ceramic slurry. The experiment showed that the favorable fluidity can be obtained by adding0.5%PVA and0.5%CMC and the viscosity of slurry decreased with the pH value increasing, when two kinds of dispersants are respectively applied,PAA-NH4and silica sol of the optimum dosage was0.7%and18%and the effect of pH value on the property of foam ceramic decreased with the content of dispersant increasing.On this basis, the effect of the two kinds of dispersants on the dispersion are investigated. Experiment shows that, compared with single dispersing, PAA-NH4(0.6%) and silica sol (10%) dispersion interaction has better dispersion stability. On this basis, the effect of grain composition and solid content of slurries on property of foam ceramic was investigated. The results of experiment show that secondary gradation could improve the foam ceramic stability.By comparing the weight loss rate, growth rate and strength recovering, the optimum coating condition was determined. The polyurethane foam interosseous membrane Can be removed effectively when hydrolyzed in20wt%NaOH solution at room temperature for3h,with its surface roughness increasing and no significant decline in elasticity.Soaked in certain solutions containing sodium carboxymethyl cellulose(CMC), polyvinyl alcohol (PVA),silica sol respectively, the slurry coating performances for the polyurethane foam were improved to different degrees, among which the polyvinyl alcohol (PVA) showed best coating effect.The effect properties of foam ceramics on different drying conditions and preparation method has been studied in this paper. Experiment shows that the ceramic foam has excellent surface properties and pore structure under vacuum,constant temperature and dry conditions.The ceramic foam dewatering regime and temperature range (200-750℃) of exhaust plastic and heating rate (0.5-0.6℃/min) were made certain by the analyzing of TG curve.The effect properties of foam ceramics on coating process and pore structure has been studied in this paper.The amounts of coating was39.1, which can be obtained by recoating at the sintering temperature (1500℃).That can ensure the ceramic foam porosity of81%. The effect of the sintering additive and sintering stabilizer on ZrO2stability was investigated.On this basis, foam ceramic mechanical performance was affected by the content of Al2O3and sintering system was studied. Experimental results show that sintering aids, can reduce the sintering temperature and improve the foam ceramics mechanical properties. When its porosity is81%, the compressive strength is1.04Mpa... |
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