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.

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.

scholarly journals Effect of inoculum to substrate ratio on biogas production of sheep paunch manure

2016 ◽  
Vol 62 (No. 1) ◽  
pp. 8-14 ◽  
Author(s):  
A.A. Lawal ◽  
A.U. Dzivama ◽  
M.K. Wasinda
Keyword(s):  
Biogas Production ◽  
Coefficient Of Determination ◽  
Order Kinetic ◽  
Production Rates ◽  
Exponential Equation ◽  
First Order ◽  
Gompertz Equation ◽  
Volatile Solids ◽  
Substrate Ratio ◽  
Order Kinetic Equation

Sheep paunch manure was anaerobically digested to study the effect of inoculum to substrate ratio on biogas production rates and accumulation. Inoculum to substrate ratios of 1.37, 2.05 and 4.1 were digested in biodigesters labelled R1, R2 and <br /> R3 respectively. Results showed that inoculum to substrate ratio had a significant effect on biogas production rates and accumulation. Biogas production rates increased to peak in the order of R3 (0.30526 Nm<sup>3</sup>/kg volatile solids (VS) days), R2 (0.15308 Nm<sup>3</sup>/kg VS d) and R1 (0.11009 Nm<sup>3</sup>/kg VS d) on the 5<sup>th</sup> day. The biogas production accumulation increased from 0.57195 to 1.46784 Nm<sup>3</sup>/kg VS as the inoculum to substrate ratio increased. The result of regression showed that coefficient of determination values for the linear equation ranged from 0.707 to 0.797, while the exponential equation had higher values that ranged from 0.7718 to 0.9929 showing better simulation. The modified Gompertz equation showed better simulation of the biogas production accumulation than the first order kinetic equation due to its higher coefficient of determination values.

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.

Porous Ceramics for High Temperature Filters

2008 ◽  
Vol 47-50 ◽  
pp. 960-963
Author(s):  
Cristina Ghitulica ◽  
Ecaterina Andronescu ◽  
O. Nicola ◽  
Mihaela Birsan
Keyword(s):  
Ceramic Powder ◽  
Mineralogical Composition ◽  
Porous Ceramics ◽  
Precipitation Method ◽  
Mechanical Resistance ◽  
Thermal Treatments ◽  
High Chemical ◽  
Low Thermal Expansion ◽  
Co Precipitation ◽  
High Chemical Stability

Cordierite based ceramic porous materials are very promising for filtering applications, due to their low thermal expansion coefficient, but also due to high chemical stability and good mechanical resistance. The cordierite powders were obtained through the co-precipitation method, while the porous ceramics were prepared by mixing the ceramic powder with an organic compound, which will burn during consequent thermal treatments, leading to an open pore ceramic web. Samples with different proportions of glucose were thermally treated at temperatures between 1050 and 1400oC. The samples were analyzed in what it concerns the mineralogical composition, open porosity and pores distribution, compressive strength and microstructure.

Porous ceramics with tri-modal pores prepared by foaming and starch consolidation

2008 ◽  
Vol 34 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Xiaojian Mao ◽  
Shiwei Wang ◽  
Shunzo Shimai
Keyword(s):  
Porous Ceramics ◽  
Starch Consolidation

scholarly journals The Erythropoietic Effect of Urine and Plasma of Repeatedly Bled Rabbits

Blood ◽  
1954 ◽  
Vol 9 (4) ◽  
pp. 299-309 ◽  
Author(s):  
G. HODGSON ◽  
J. TOHÁ
Keyword(s):  
Folic Acid ◽  
Hemoglobin Concentration ◽  
Significant Rise ◽  
Repeated Injection ◽  
Cent Oxygen ◽  
Rabbit Plasma ◽  
Exponential Equation ◽  
First Order ◽  
Standard Manner ◽  
High Concentrations

Abstract 1. The reticulocyte response of rabbits bled in a standard manner is significantly greater after the injection of anemic rabbit plasma, than after the injection of normal rabbit plasma. The effect of anemic rabbit plasma disappears after the exposure to 100 per cent oxygen, but not after exposure to air. The activity of anemic rabbit plasma is not due to the presence of high concentrations of vitamin B12 or folic acid. 2. The recovery of hemoglobin concentration after a standard hemorrhage is described by a first order exponential equation. The speed of recovery is characterized by the time constant of regeneration. The velocity of hemoglobin regeneration, after a standard hemorrhage in rabbits injected with plasma of anemic animals, is greater than that of controls injected with normal rabbit plasma. Anemic rabbit plasma loses its erythropoietic effect after boiling at pH 5.5 for 15 minutes. 3. The repeated injection of anemic rabbit plasma in normal rabbits produces a significant rise of reticulocytes, erythrocytes, and hemoglobin concentration. 4. The injection of urine of anemic animals increases the speed of hemoglobin regeneration after a standard hemorrhage in rabbits. The activity of the urine of anemic rabbits is lost by boiling at pH 9.0 for 5 minutes, but not after the same treatment at pH 5.5. Urine of anemic animals loses its erythropoietic action after 16 hours dialysis. 5. It is concluded that the plasma and urine of animal with increased erythropoiesis contains a factor or factors (erythropoietins) which are probably the humoral mediators of the primary erythropoietic stimulus.

scholarly journals Catalyst Particle Porosity Effect upon Flameless Combustion Characteristics

2020 ◽  
Vol 21 (1) ◽  
pp. 124-131
Author(s):  
V. V. Kalinchak ◽  
A. S. Chernenko ◽  
A. F. Fedorenko ◽  
A. N. Sofronkov ◽  
V. V. Kramarenko
Keyword(s):  
Mass Transfer ◽  
Spontaneous Combustion ◽  
Catalyst Particle ◽  
Order Reaction ◽  
Gas Mixture ◽  
Porous Catalyst ◽  
First Order ◽  
Inner Surface ◽  
Reaction Proceeds ◽  
Porosity Effect

The problem of heat and mass transfer of a porous catalyst particle is considered. On the her surface, including the inner surface of the pores, an irreversibly heterogeneous first-order reaction proceeds. It has been analytically shown that in a heated gas mixture, the catalyst's porosity reduces the minimum impurity's concentration of catalytic spontaneous combustion in the mixture and increases the catalyst particle's corresponding diameter. This concentration corresponds to the external kinetic and internal diffusion reaction's modes.

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