Microstructural, Physical and Mechanical Analysis of Rha Pore Modified Porous Alumina with Aluminum as Reinforcement (original) (raw)
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Graphite waste from primary batteries, active yeast and commercial rice husk ash have been used as pore-forming agents to fabricate porous alumina ceramics using a fugitive materials technique. The pore-forming agent ratios were between 10 to 50 wt %. The effects of the pore-forming agent ratios on the mechanical properties, the porosity and the microstructure have been investigated in this study. The results showed that through increasing the pore-forming agent ratio for graphite waste, yeast and rice husk ash, the porosity increased from 37.3 to 61.1%, 30.2 to 63.8% and 42.9 to 49.0%, respectively. The hardness also decreased from 172.6 to 38.1 HV 1 and from 160.6 to 15.0 HV 1 for porous alumina ceramics using graphite waste and yeast as pore-forming agents, respectively. However, the hardness of the porous alumina ceramics with rice husk ash as a pore-forming agent increased at 30 wt % (150.9 HV 1) and 50 wt % (158.9 HV 1). The tensile strength for porous alumina ceramics using graphite waste and yeast as pore-forming agents decreased from 24.9 to 14.3 MPa and from 26.2 to 5.4 MPa. The compressive strength decreased from 112.3 to 34.3 MPa and from 19.5 to 1.8 MPa, respectively. However, for porous alumina ceramics using rice husk ash, the tensile strength increased at 30 wt % (24.1 MPa) and 50 wt % (21.9 MPa). The compressive strength also increased at 30 wt % (69.7 MPa) and at 50% (60.1 MPa).
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Production of porous alumina ceramics by the slurry casting method and pore formation by elimination of hydrogen as a result of a chemical reaction of aluminium powder with water is investigated. Such ceramics has a low mechanical strength. The purpose of the study was to determine various ways of producing high porosity alumina ceramics with a rather high mechanical strength and other properties significant for refractory ceramics. Some additives, both organic (Optapix) and inorganic (kaolin and silica), are used. The properties and structure of the obtained materials, such as bulk density, bending strength, porosity, pore size distribution, thermal shock resistance, depend on the grain size of raw materials, the viscosity of suspension, the type of additives and on the sintering temperature. Materials are sintered at a temperature of 1600 °C.
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This paper investigates influence of thermal treatment on the microstructure and properties of porous alumina-starch ceramics. The porous bodies were prepared through polymeric sponge method. The dried slurry of alumina and starch mixture was crushed and sieved on a 63 μm screen. The undersize particles were pre-sintered in the powder form at 1100, 1200, 1300, 1400 and 1500°C for 2 hours in an air furnace. The pressed forms of ceramic powder then sintered at 1500°C to produce porous alumina ceramic bodies with porosity from 25.9 to 31.2%. The modulus of rupture has successfully been improved about five times higher compared to the strength of porous ceramic body without presintering process. Besides that, the hardness value for double sintered porous ceramic was increased to 35.90 HV. SEM micrographs revealed better microstructural features of the ceramic body produced from pre-sintered samples. Based on the results obtained, pre-sintered process in the preparation of alumina-starch...
Ceramics International, 2018
An innovative approach for fabricating porous alumina ceramics (PACs) with improved mechanical and thermal properties using walnut shell powders as pore-forming agent combined with alumina sol impregnation is reported in the present work. It is demonstrated that uniform distribution of spherical pores can be observed in asprepared PACs by using above technical route. The decrease of walnut shell powder sizes significantly promotes the enhancement of crushing strength and reduction of thermal conductivity of the PACs. Meanwhile, the impregnated alumina sol is favoring for the formation of spherical micro-pores, then further improves their mechanical and thermal insulation performances. The lowest thermal conductivity and highest crushing strength of resulting sample reach 0.16 W/m K and 29.2 MPa, respectively. This novel method offers new possibilities to fabricate high-quality PACs.
Effect of thermal treatment on properties and microstructures of porous alumina
Solid State Science and Technology, Vol. 18,, 2010
This paper investigates influence of thermal treatment on the microstructure and properties of porous alumina-starch ceramics. The porous bodies were prepared through polymeric sponge method. The dried slurry of alumina and starch mixture was crushed and sieved on a 63 μm screen. The undersize particles were pre-sintered in the powder form at 1100, 1200, 1300, 1400 and 1500° C for 2 hours in an air furnace. The pressed forms of ceramic powder then sintered at 1500° C to produce porous alumina ceramic bodies with porosity ...
A porous ceramic is made from composite materials which consist of alumina and commercial rice husk ash. This type of ceramics is obtained by mixing the commercial rice husk ash as a source of silica (SiO 2) and a pore forming agent with alumina (Al 2 O 3) powder. To obtain this type of ceramic, a solid-state technique is used with sintering at high temperature. This study also investigated the effects of the rice husk ash ratios on the mechanical properties, porosity, and microstructure. The results showed that, by increasing the content of the rice husk ash from 10 to 50 wt%, there is an increase in the porosity from 42.92% to 49.04%, while the mechanical properties decreased initially followed by an increase at 30 wt% and 50 wt%; the hardness at 20 wt% of the ash content was recorded at 101.90 HV 1. When the ash content was increased to 30 wt% and 50 wt%, the hardness was raised to 150.92 HV 1 and 158.93 HV 1 , respectively. The findings also revealed that the tensile and compressive strengths experienced a decrease at 10 wt% of the ash content and after that increase at 30 wt% and 50 wt% of rice husk ash. XRD analysis found multiple phases of ceramic formation after sintering for the different rice husk ash content.
Alumina ceramics prepared with new pore-forming agents
Processing and Application of Ceramics, 2008
Porous ceramics have a wide range of applications at all length scales, ranging from fi ltration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths) and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs) of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed), which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 μm (rice starch) to approximately 1 mm (poppy seed), all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds) and starch consolidation casting (using metal molds) are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry).
Ceramics International, 2012
This work aims at studying the influence of thermal treatment on the microstructure, resistivity and technological properties of porous alumina ceramics prepared via starch consolidation casting (SCC) technique. Colloidal suspensions were prepared with three different contents of alumina solid loading (55, 60 and 65 mass%) and corn starch (3, 8 and 13 mass%). The sintered samples at 1400, 1500, 1600 and 1700 8C, show open porosity between 46 and 64%, depending on the starch content in the precursor suspensions and sintering temperature. The pore structures were analyzed by SEM. The effect of corn starch content on the apparent porosity, pore size distribution, linear shrinkage and electrical resistivity as well as cold crushing strength of the sintered porous alumina ceramics was also measured. These porous alumina ceramics are promising porous ceramic materials for using in a wide range of thermal, electrical and bioceramics applications as well as filters/membranes and gas burners, due to their excellent combination properties.