Anisotropy of Compressive Strength in Porous Alumina Ceramics

2014 ◽  
Vol 604 ◽  
pp. 153-156 ◽  
Author(s):  
Ieva Zake-Tiluga ◽  
Ruta Svinka ◽  
Visvaldis Svinka
Keyword(s):  
Compressive Strength ◽  
Sintering Temperature ◽  
Porous Alumina ◽  
Slip Casting ◽  
Mechanical Anisotropy ◽  
Alumina Ceramics ◽  
Casting Method ◽  
Concrete Technology ◽  
Pore Former ◽  
Aerated Concrete

Anisotropy of the compressive strength was investigated in porous alumina based ceramics produced by slip casting method. Aluminium paste was used as pore former similarly as in the aerated concrete technology. Materials were sintered at 1650°C and 1750°C. The apparent porosity of the investigated materials was in the range of 54±1% to 60±2%. The compressive strength of the samples in the directions parallel and perpendicular to the sample expansion direction was in the range from 3.8±0.3 to 13.0±1.1 MPa and from 6.4±1.3 to 27.0±1.1 MPa, respectively. The mechanical anisotropy was related with the flattening of the introduced pores. The level of mechanical anisotropy was affected by the initial composition of the slurry and sintering temperature.

Porous Alumina Ceramics Fabricated by Freeze Casting Method

2012 ◽  
Vol 518-523 ◽  
pp. 665-668
Author(s):  
Kai Hui Zuo ◽  
Yu Ping Zeng ◽  
Qing Ling Lin
Keyword(s):  
Fracture Strength ◽  
Open Porosity ◽  
Sintering Temperature ◽  
Porous Alumina ◽  
Freeze Casting ◽  
Alumina Ceramics ◽  
Casting Method

Alumina ceramics with inter-connected pores were fabricated by freeze casting method. The open porosity and fracture strength were controlled by the concentration of Al2O3 slurry and sintering temperature. Sintered at 1600°C, the open porosity and fracture strength of Al2O3 ceramics fabricated by the slurry with concentration of 70wt% are 46.4% and 23.8 MPa, respectively.

scholarly journals Optimization of Sintering Process of Alumina Ceramics Using Response Surface Methodology

2021 ◽  
Vol 13 (12) ◽  
pp. 6739
Author(s):  
Darko Landek ◽  
Lidija Ćurković ◽  
Ivana Gabelica ◽  
Mihone Kerolli Mustafa ◽  
Irena Žmak
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Heating Rate ◽  
Sintering Temperature ◽  
Nonlinear Models ◽  
Slip Casting ◽  
Holding Time ◽  
Alumina Ceramics ◽  
Aqueous Suspensions ◽  
Temperature Heating

In this work, alumina (Al2O3) ceramics were prepared using an environmentally friendly slip casting method. To this end, highly concentrated (70 wt.%) aqueous suspensions of alumina (Al2O3) were prepared with different amounts of the ammonium salt of a polycarboxylic acid, Dolapix CE 64, as an electrosteric dispersant. The stability of highly concentrated Al2O3 aqueous suspensions was monitored by viscosity measurements. Green bodies (ceramics before sintering) were obtained by pouring the stable Al2O3 aqueous suspensions into dry porous plaster molds. The obtained Al2O3 ceramic green bodies were sintered in the electric furnace. Analysis of the effect of three sintering parameters (sintering temperature, heating rate and holding time) on the density of alumina ceramics was performed using the response surface methodology (RSM), based on experimental data obtained according to Box–Behnken experimental design, using the software Design-Expert. From the statistical analysis, linear and nonlinear models with added first-order interaction were developed for prediction and optimization of density-dependent variables: sintering temperature, heating rate and holding time.

Fabrication and Properties of Alumina Flat Sheet Membrane Surports

2014 ◽  
Vol 955-959 ◽  
pp. 601-604
Author(s):  
De Xiang Liao ◽  
An Chao Geng ◽  
Peng Hao Su ◽  
Dao Lun Feng ◽  
Lin Lin Wang
Keyword(s):  
Sintering Temperature ◽  
Porous Alumina ◽  
Pure Water ◽  
Porous Ceramic ◽  
Water Flux ◽  
Carbon Powder ◽  
Pore Former ◽  
Alumina Support ◽  
Ceramic Support ◽  
Flat Sheet Membrane

The porous ceramic support was realized at various temperature range from 1200°C~1300°C using α-Al2O3 as main material, carbon powder as pore-former, kaolin clay and titanium dioxide as sintering aids and polyvinyl alcohol (PVA) as adhesives. The microstructures of sintered body were significantly affected by the amount of pore-former and sintering temperature. The results indicated that the porosity dramatically increased and the pore radius increased from 2.9 μm to 3.2 μm as carbon powder addition increased from 3 wt.% to 12 wt.%. Correspondingly, their pure water flux depending on the pore structure parameters of the support increased from 1.37 to 4.53 m3.m-2.h-1.bar-1. To prepare porous alumina support with 40% open porosity, carbon powder up to 10 wt.% is appropriate. Sintering experiments showed that the optimum sintering conditions are the sintering temperature of 1300 °C and 2 h holding time at this temperature.

Study on Structure and Properties of Porous Copper Alloy

2013 ◽  
Vol 833 ◽  
pp. 301-304
Author(s):  
Hao Zhong ◽  
Yun Zhou
Keyword(s):  
Compressive Strength ◽  
Relative Density ◽  
Pore Size ◽  
Alloy Powder ◽  
Sintering Temperature ◽  
Raw Material ◽  
Structure And Properties ◽  
Pore Former ◽  
Porous Copper ◽  
Increasing Trend

CuSn6Zn6 alloy powder and a pore former were used as raw material. Porous bronze was successfully prepared by the sintering and dissolution process (SDP). The porosity is in range of 76%~88%, and the pore size is in range of 0.8~3.3mm. The effect of the porosity and cell sizes of specimens on its mechanical property was investigated, and the effect of sintering temperature on its relative density and porosity was also studied. The experimental results indicate that under the condition of the same pore size, the compressive strength decreases with the increase of porosity, the compressive strength changes from 10Mpa to 2Mpa with the porosity from 76% to 88%; under the same porosity condition, the compressive strength does not change significantly with the pore size, but it has a slightly increasing trend with the decrease of the pore size. The relative density of the specimens increases with the increase of the sintering temperature.

Modification of Porous Cordierite Ceramic

2016 ◽  
Vol 721 ◽  
pp. 322-326
Author(s):  
Ruta Švinka ◽  
Visvaldis Svinka ◽  
Julija Bobrovik
Keyword(s):  
Compressive Strength ◽  
Thermal Expansion ◽  
Large Scale ◽  
Sintering Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Slip Casting ◽  
Concentrated Suspension ◽  
Cordierite Ceramic ◽  
Silica Additive ◽  
Porous Cordierite

Highly porous cordierite ceramic by using of talcum, kaolinite and γ-alumina was obtained by method of slip casting of concentrated suspension. Additives of amorphous silica and non-stabilized zirconia in the amount of 5 wt% were used. Sintering temperature of dried samples was in range of 1250 – 1450°C. All the samples contain crystalline phases of cordierite, mullite and corundum but, depending on the additives, as a result of sintering in addition forms spinel, cristobalite or zircon (ZrSiO4). Porosity of obtained materials changes in large scale from 42 to 59 per cent; it is influenced by both sintering temperature and composition. Compressive strength increases with the addition of zirconia. In comparison, compressive strength of samples without additives or with silica additive does not exceed 3.5 MPa. The increase of coefficient of thermal expansion depends both on the composition and sintering temperature. ZrO2 additive increases the coefficient of thermal expansion considerably.

Functional Gradient Alumina Ceramics with Controlled Porosity

2007 ◽  
Vol 333 ◽  
pp. 223-226
Author(s):  
Jana Andertová ◽  
Jiří Havrda ◽  
Radek Tláskal
Keyword(s):  
Sol Gel ◽  
Slip Casting ◽  
Physical And Mechanical Properties ◽  
Alumina Ceramics ◽  
Casting Method ◽  
Functional Gradient ◽  
Variable Porosity ◽  
Controlled Porosity ◽  
Sol Gel Transition ◽  
Gel Transition

The work deals with preparation of functional gradient alumina ceramics with controlled porosity by slip casting method of aqueous alumina suspension containing pore-generating agent. The sol-gel transition of AlO(OH) was employed to stabilize pore-generating agent in the suspension. The composite bodies with layers of variable porosity were prepared. Based on dilatometer measurement the admission difference of irreversible dilatation changes #αirr between compounded layers was determined in order to prepare defect free bi-layer bodies. The dependence of physical and mechanical properties of as fired composite bodies on the porosity value was expressed.

scholarly journals Alumina ceramics prepared with new pore-forming agents

2008 ◽  
Vol 2 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Zuzana Zivcová ◽  
Eva Gregorová ◽  
Willi Pabst
Keyword(s):  
Thermal Analysis ◽  
Porous Alumina ◽  
Slip Casting ◽  
Porous Ceramics ◽  
Rice Starch ◽  
Alumina Ceramics ◽  
Poppy Seed ◽  
Biological Origin ◽  
Filtration Membranes ◽  
Wide Range

Porous ceramics have a wide range of applications at all length scales, ranging from filtration 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 ?m (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).

Porous Alumina through Protein Foaming-Consolidation Method: Effect of Stirring Time and Drying Temperature on the Physical Properties

2010 ◽  
Vol 93-94 ◽  
pp. 397-400 ◽  
Author(s):  
Ahmad Fadli ◽  
Iis Sopyan
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Porous Alumina ◽  
Egg Yolk ◽  
Optimum Composition ◽  
Alumina Ceramics ◽  
Drying Temperature ◽  
Porous Bodies ◽  
Method Effect ◽  
Stirring Time

The porous alumina ceramics were fabricated through protein foaming-consolidation method using egg yolk as pore creating agent. The influence of stirring time and drying temperature on the physical properties of the porous bodies was investigated. The porosity of the 3 h stirring time’s sample was 42% and it increased to 71% at 24 h stirring time. As the drying temperature increased, the pores became interconnected with less dense and thinner pore and were found in the range of 100-650 µm. The density of 180°C drying temperature’s sample was 1.5 g/cm3 and it increased to1.9 g.cm-3 when dried at 100°C. An alumina-to-yolk ratio of 1.4 in weight was found to be optimum composition to give porous bodies with higher compressive strength. The compressive strength of the porous bodies increased from 3.7 MPa at 61.1% porosity to 7.7 MPa at 42.5% porosity, showing that the compressive strength is strongly dependent on porosity.

scholarly journals Fabrication of Highly Porous Alumina-Based Ceramics with Connected Spaces by Employing PMMA Microspheres as a Template

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Kazutaka Kamitani ◽  
Takeo Hyodo ◽  
Yasuhiro Shimizu ◽  
Makoto Egashira
Keyword(s):  
Particle Size ◽  
Pore Diameter ◽  
Porous Alumina ◽  
Slip Casting ◽  
Connected Space ◽  
Casting Method ◽  
Sintering Aid ◽  
Subsequent Calcination ◽  
Different Diameters ◽  
Highly Porous

Highly porous alumina-based ceramics were fabricated by a slip casting method by employing polymethylmethacrylate (PMMA) microspheres having different diameters as a template and MgO or SiC powder as a sintering aid and subsequent calcination at . Spherical pores reflecting the morphology of the PMMA microspheres could be fabricated. In addition, the formation of much smaller connected space among the pores was observed on the pore's inner walls of all ceramics. In this method, porous structure, for example, pore diameter, shape (open or closed), and mechanical properties, could be controlled by varying the particle size of PMMA microspheres and its concentration in alumina-based slurries. Highly porous and mechanically strong alumina-based ceramics having an open porosity of 62%, a connected space size of 1.3 m, and a compressive strength of 147.6 MPa could be fabricated by employing PMMA microspheres with a mean particle size of 22.6 m and an appropriate amount of SiC.

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