Porous Ceramics Obtained by Slip/Starch Casting Consolidation Method (SSCC)

2016 ◽  
Vol 881 ◽  
pp. 52-57
Author(s):  
Rodrigo Sampaio Fernandes ◽  
Elson de Campos ◽  
Jerusa Góes Aragão Santana ◽  
Rogério Pinto Mota
Keyword(s):  
Slip Casting ◽  
Porous Ceramics ◽  
Mechanical Resistance ◽  
Alumina Ceramics ◽  
Forming Process ◽  
Porous Mold ◽  
Different Characteristics ◽  
Starch Consolidation ◽  
Resistance Value ◽  
Gelling Process

Slip/starch casting consolidation (SSCC) is a technique for obtaining porous ceramics, which joins the forming process by starch consolidation with the slip casting method. In this work, a slip which contains ceramic powders, starch and dispersant, is poured into a porous mold and is taken to an oven so that the gelling process occurs. After sintering, it is noticed that the ceramics show different characteristics from the ones obtained exclusively by slip casting or by starch consolidation. Alumina ceramics were produced by using the three methods presented in this work. The ceramics were characterized by apparent porosity, mechanical resistance and scanning electron microscopy. The ceramics produced by SSCC presented the highest mechanical resistance value (289 MPa), while the ones produced by starch consolidation and slip casting presented values of 126 MPa and 191 MPa, respectively.

Effect of Different Solid Amounts in the Physical and Microscopical Properties of SiC Porous Ceramics

2008 ◽  
Vol 591-593 ◽  
pp. 685-690 ◽  
Author(s):  
Jerusa Góes Aragão Santana ◽  
José Luiz Minatti ◽  
Élson de Campos ◽  
Francisco Cristóvão Lourenço de Melo ◽  
Tetunori Kajita
Keyword(s):  
Organic Material ◽  
Thermal Stresses ◽  
Ceramic Powder ◽  
Porous Ceramics ◽  
Forming Process ◽  
Solid Load ◽  
Starch Consolidation ◽  
Sintering Processes ◽  
Roughness Measurements

The presence of pores in ceramics is directly related to the chosen forming process. So, in the starch consolidation method, the ceramics show, after burning, pores with morphology similar to that presented by this organic material. On the other hand, the increase in solid load leads up to alterations in dispersion viscosity, increasing the thermal stresses during drying and sintering processes. In order to verify the solid percentage influence in ceramic final properties, samples were prepared with silicon carbide in different compositions using or not starch as binder agent and pore forming element. The characterization of the ceramic pieces was performed by superficial roughness measurements, porosity besides by optical and scanning electron microscopy. The results showed ceramics with SiC and starch presented physical and microscopic properties slightly higher in relation to those with only ceramic powder in their composition. The presence of organic material, agglomerated and foam during the forming were essential for the final properties of the studied samples.

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).

Alumina Porous Ceramics: Mathematical Behavior at Different Commercial Starch Concentration

2008 ◽  
Vol 591-593 ◽  
pp. 442-447 ◽  
Author(s):  
Rodrigo Sampaio Fernandes ◽  
Élson de Campos ◽  
José Luiz Minatti ◽  
Jerusa Góes Aragão Santana ◽  
Rogério Pinto Mota
Keyword(s):  
Porous Ceramics ◽  
Mechanical Resistance ◽  
Flexural Test ◽  
Exponential Equation ◽  
Weibull Statistics ◽  
Starch Concentration ◽  
First Order ◽  
Porosity Effect ◽  
Mathematical Behavior ◽  
Starch Consolidation

Several researches have been developed in order to verify the porosity effect over the ceramic material properties. The starch consolidation casting (SCC) allows to obtain porous ceramics by using starch as a binder and pore forming element. This work is intended to describe the porous mathematical behavior and the mechanical resistance at different commercial starch concentration. Ceramic samples were made with alumina and potato and corn starches. The slips were prepared with 10 to 50 wt% of starch. The specimens were characterized by apparent density measurements and three-point flexural test associated to Weibull statistics. Results indicated that the porosity showed a first-order exponential equation e-x/c increasing in both kinds of starches, so it was confirmed that the alumina ceramic porosity is related to the kind of starch used.

Aluminum Oxide Ceramics Obtained by Commercial Starch Consolidation with Gradient Porosity

2010 ◽  
Vol 63 ◽  
pp. 175-180
Author(s):  
Rogério Pinto Mota ◽  
Rodrigo Sampaio Fernandes ◽  
Élson de Campos ◽  
Emerson Ferreira de Lucena ◽  
Mauricio A. Algatti
Keyword(s):  
Present Method ◽  
Mass Concentration ◽  
Light And Electron Microscopy ◽  
Porous Ceramics ◽  
Oxide Ceramics ◽  
Water Drainage ◽  
Density Measurements ◽  
The Common ◽  
Starch Consolidation ◽  
Gelling Process

The starch consolidation technique is commonly used for obtaining porous ceramics due to bonding and porous-maker starch characteristic during gelling process. The method adopted here improved the water drainage by using a plaster porous base (70 and 90 consistency values) improving the water drainage by action of gravity and the capillary effect. It used slip with 50 vol% solids and as precursors oxide A-1000SG and commercial cornstarch with a mass concentration varying from 10 to 40%. For comparison between the present method and the common one, slip was put in impermeable and permeable base moulds. The gelling occurred at 70°C for 2 hours and the drying at 110°C. Pre-sintering was carried out at 1000°C and the sintering at 1600°C with a plateau of 1 hour. Results showed that the plaster consistency of the mould bases was preponderant on ceramics porosity. Porosity and apparent density measurements using light and electron microscopy revealed variation of 5% of porosity from the top to the bottom of the samples.

Microscopy of porous ceramics

1989 ◽  
Vol 47 ◽  
pp. 438-439
Author(s):  
H. M. Kerch ◽  
R. A. Gerhardt
Keyword(s):  
Porous Ceramics ◽  
Specimen Preparation ◽  
High Porosity ◽  
Ion Milling ◽  
Forming Process ◽  
Preparation Methods ◽  
Pore Texture ◽  
Proper Design ◽  
And Function ◽  
Function Information

Highly porous ceramics are employed in a variety of engineering applications due to their unique mechanical, optical, and electrical characteristics. In order to achieve proper design and function, information about the pore structure must be obtained. Parameters of importance include pore size, pore volume, and size distribution, as well as pore texture and geometry. A quantitative determination of these features for high porosity materials by a microscopic technique is usually not done because artifacts introduced by either the sample preparation method or the image forming process of the microscope make interpretation difficult.Scanning electron microscopy for both fractured and polished surfaces has been utilized extensively for examining pore structures. However, there is uncertainty in distinguishing between topography and pores for the fractured specimen and sample pullout obscures the true morphology for samples that are polished. In addition, very small pores (nm range) cannot be resolved in the S.E.M. On the other hand, T.E.M. has better resolution but the specimen preparation methods involved such as powder dispersion, ion milling, and chemical etching may incur problems ranging from preferential widening of pores to partial or complete destruction of the pore network.

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.

Environmental footprint as a criterion in the ZTA composites forming process via centrifugal slip casting

2021 ◽  
Author(s):  
Justyna Zygmuntowicz ◽  
Justyna Tomaszewska ◽  
Radosław Żurowski ◽  
Marcin Wachowski ◽  
Ireneusz Szachogłuchowicz ◽  
...  
Keyword(s):  
Slip Casting ◽  
Environmental Footprint ◽  
Forming Process

Leveling Quality Prediction Algorithm

2015 ◽  
Vol 809-810 ◽  
pp. 235-240
Author(s):  
Catalina Maier ◽  
Robin Gauthier
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Theoretical Model ◽  
Cumulative Effect ◽  
Prediction Algorithm ◽  
Forming Process ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Experimental Values ◽  
Different Characteristics

Roller leveling is a forming process which used to minimize flatness imperfection and residual stresses by repeated forming process of a sheet metal. The determination of the machine settings must be very accurate and ask a precise mechanical study. In order to determine an algorithm which can predict the leveling quality according to the machine settings we start by a theoretical model of stress evolution during the process. The plastification ratio is deducted from this one and the values obtained by this approach are compared whit experimental values. The finite element analysis is performed, in second step in order to assure a good accuracy of the prediction algorithm. Theoretical study determines a minimum of the plastification ratio according to the machine settings. The finite element analysis gives more accurate results due to the consideration of different characteristics of the process, neglected by the theoretical model: cumulative effect of bending/unbending with stretching of the sheet during the passing between each couple of rolls, boundary conditions at the limit of the material deformed by two adjoining couples of rolls, friction force.

Effects of Pore Morphology on the Fabrication and Mechanical Properties of Porous Si3N4 Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1231-1236
Author(s):  
Jian Feng Yang ◽  
Ji Qiang Gao ◽  
Guo Jun Zhang ◽  
Ichiro Hayashi ◽  
Tatsuki Ohji
Keyword(s):  
Mechanical Properties ◽  
Gas Permeability ◽  
Slip Casting ◽  
Porous Ceramics ◽  
Pore Morphology ◽  
Porous Si ◽  
Die Pressing ◽  
Porous Si3n4 ◽  
Si3n4 Ceramics ◽  
Porous Si3n4 Ceramics

Porous Si3N4 ceramics with different pore morphology have been fabricated, utilizing either organic whiskers or starch as the fugitive agents, through slip-casting and die-pressing technique, respectively. The obtained porous ceramics have rod shaped or equiaxial pore morphology, originated from there two kinds of pore forming agents. The mechanical properties were investigated. The strength decreased considerably when small amount of whiskers were added, however, further increase in the whisker content only cause a moderate decrease of the strength. Gas permeability were measured for the samples with high whisker content of 60 vol% (corresponding to porosity of about 45% in the sintered bodies), and was compared with the counterpart contained the same porosity in which pores were equiaxial. The flexural strength of the samples with these two types of fugitive particles was almost the same, but the permeability of samples with rod-shaped pores were much higher than that with equiaxial pores, which can be understood in terms of a short pass model.

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