The objective of this work was to determine the optimum size and amount of raw materials which influence the viscosity of ceramic paste using the experimental design for the production of tubular support by the extrus...The objective of this work was to determine the optimum size and amount of raw materials which influence the viscosity of ceramic paste using the experimental design for the production of tubular support by the extrusion technique and its application in microfiltration. The Box Behnken design was used to optimize the viscosity of the ceramic paste. ANOVA was used to model the system represented by independent parameters and dependent output response and to optimize the system by estimating the statistical parameters. A three-factor and three-level design was used generating thus 15 experiments. The independent factors were the amount of porogen, size of porogen and amount of binder and dependent factor the viscosity of the ceramic paste. The minimum (−1), intermediate (0) and maximum (+1) level of the amount of porogen, size of porogen and amount of binder used were 20 g, 30 g and 40 g, 50 μm, 100 μm and 150 μm, and 2 g, 3.5 g and 5 g respectively. The statistical analyses showed that the values of the answers would adapt to a second degree polynomial model. The R-square value obtained was greater than 95%, the Biais factor was equal to the unit and the Absolute Average Deviation (AAD) equal to the zero thus validating the model. The optimal size of raw material was found to be 100 μm for an amount of clay of 66 g, amount of porogen of 30 g and amount of binder of 4 g. The optimum viscosity of the ceramic paste was found to be 26.7 Pa∙s which is close to the viscosity of the clay paste only found to be 28.5 Pa∙s, thus good for shaping by the extrusion technique. The ceramic paste showed a pseudo-plastic behavior. The tubular porous support was sintered at 950°C and the dimensions, such as outer and inner diameters and length of the tube were 4 cm, 2 cm, and 19 cm, respectively. The sintered membrane possesses a porosity of 43.5%, water permeability of 244.9 L/h∙m2 bar, an average pore size of 2.4 μm and mechanical strength of 9.2 MPa with very good corrosion resistance in acidic and 展开更多
Extrusion freeforming can be used for the rapid prototyping of millimeter-wave electromagnetic bandgap (EBG) structures. In this work, an alumina-polymer paste with a relatively high volatility solvent (propanol) was ...Extrusion freeforming can be used for the rapid prototyping of millimeter-wave electromagnetic bandgap (EBG) structures. In this work, an alumina-polymer paste with a relatively high volatility solvent (propanol) was used and the characteristics of the ceramic paste, particularly the rheological features are described. The advantage of high volatility solvent is that the viscosity and elastic modulus of the paste are increased sharply as the solvent evaporates. Thus, the rigidity of the extruded filament is quickly increased as a small amount of solvent evaporates. Finally, by employing this procedure, different EBG structures such as 2-D, 3-D woodpile and aperiodic structures were fabricated and their bandgaps were measured. The experimental results show that extrusion freeforming is a relatively simple and easy method to fabricate these woodpile structures with a bandgap in the 90-110 GHz region.展开更多
文摘The objective of this work was to determine the optimum size and amount of raw materials which influence the viscosity of ceramic paste using the experimental design for the production of tubular support by the extrusion technique and its application in microfiltration. The Box Behnken design was used to optimize the viscosity of the ceramic paste. ANOVA was used to model the system represented by independent parameters and dependent output response and to optimize the system by estimating the statistical parameters. A three-factor and three-level design was used generating thus 15 experiments. The independent factors were the amount of porogen, size of porogen and amount of binder and dependent factor the viscosity of the ceramic paste. The minimum (−1), intermediate (0) and maximum (+1) level of the amount of porogen, size of porogen and amount of binder used were 20 g, 30 g and 40 g, 50 μm, 100 μm and 150 μm, and 2 g, 3.5 g and 5 g respectively. The statistical analyses showed that the values of the answers would adapt to a second degree polynomial model. The R-square value obtained was greater than 95%, the Biais factor was equal to the unit and the Absolute Average Deviation (AAD) equal to the zero thus validating the model. The optimal size of raw material was found to be 100 μm for an amount of clay of 66 g, amount of porogen of 30 g and amount of binder of 4 g. The optimum viscosity of the ceramic paste was found to be 26.7 Pa∙s which is close to the viscosity of the clay paste only found to be 28.5 Pa∙s, thus good for shaping by the extrusion technique. The ceramic paste showed a pseudo-plastic behavior. The tubular porous support was sintered at 950°C and the dimensions, such as outer and inner diameters and length of the tube were 4 cm, 2 cm, and 19 cm, respectively. The sintered membrane possesses a porosity of 43.5%, water permeability of 244.9 L/h∙m2 bar, an average pore size of 2.4 μm and mechanical strength of 9.2 MPa with very good corrosion resistance in acidic and
基金Supported by the Leverhulme Trust (No. F/07476/V)
文摘Extrusion freeforming can be used for the rapid prototyping of millimeter-wave electromagnetic bandgap (EBG) structures. In this work, an alumina-polymer paste with a relatively high volatility solvent (propanol) was used and the characteristics of the ceramic paste, particularly the rheological features are described. The advantage of high volatility solvent is that the viscosity and elastic modulus of the paste are increased sharply as the solvent evaporates. Thus, the rigidity of the extruded filament is quickly increased as a small amount of solvent evaporates. Finally, by employing this procedure, different EBG structures such as 2-D, 3-D woodpile and aperiodic structures were fabricated and their bandgaps were measured. The experimental results show that extrusion freeforming is a relatively simple and easy method to fabricate these woodpile structures with a bandgap in the 90-110 GHz region.
