scholarly journals Comparative evaluation of properties of a clay based ceramic shaped via four techniques

Cerâmica ◽  
2018 ◽  
Vol 64 (370) ◽  
pp. 176-182 ◽  
Author(s):  
C. I. Torres ◽  
N. M. Rendtorff ◽  
M. Cipollone ◽  
E. F. Aglietti ◽  
G. Suárez
Keyword(s):  
Sintering Temperature ◽  
Continuous Process ◽  
Slip Casting ◽  
Textural Properties ◽  
Batch Process ◽  
Ceramic Ware ◽  
Kaolinite Clay ◽  
Qualitative And Quantitative ◽  
Quantitative Properties ◽  
Forming Methods

Abstract The results of qualitative and quantitative properties of clay based ceramic are presented in this work. Four different shaping methods and sintering temperatures were used to understand their influence in the final properties of a ceramic material formulated using kaolinite clay and calcined alumina. This material can be used as a structural ceramic for different applications, and there is no pre-established relation between the forming method and the final sintered properties. Forming methods used to prepare the samples were uniaxial pressing (a batch process that allows application in dry samples), extruding (a continuous process that requires moisture), slip casting (a process that allows to shape complex ceramic ware), and lamination (a batch process that requires moisture). Sintering temperatures were in the range of 1100 and 1400 °C. In order to compare how properties behave as the shaping method and sintering temperature change, textural properties, shrinkage, porosimetry, phase composition and mechanical strength were evaluated and analyzed. Scanning electron microscopy and microtomography were employed for analyzing and comparing the developed microstructures. Differences in the resulting properties are explained in terms of the developed crystalline phases and microstructure.

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.

scholarly journals Some New Volterra-Fredholm-Type Discrete Inequalities and Their Applications in the Theory of Difference Equations

2011 ◽  
Vol 2011 ◽  
pp. 1-24 ◽  
Author(s):  
Bin Zheng ◽  
Qinghua Feng
Keyword(s):  
Difference Equations ◽  
Fredholm Type ◽  
Qualitative And Quantitative ◽  
Independent Variables ◽  
Discrete Inequalities ◽  
Quantitative Properties ◽  
Two Independent Variables

Some new Volterra-Fredholm-type discrete inequalities in two independent variables are established, which provide a handy tool in the study of qualitative and quantitative properties of solutions of certain difference equations. The established results extend some known results in the literature.

scholarly journals Food Grade Ethanol Production Process of Sorghum Stem Juice Using Immobilized Cells Technique

2015 ◽  
Vol 9 (7) ◽  
pp. 8 ◽  
Author(s):  
Tri Widjaja ◽  
Ali Altway ◽  
Arief Widjaja ◽  
Umi Rofiqah ◽  
Rr Whiny Hardiyati Erlian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Sieve ◽  
Zymomonas Mobilis ◽  
Immobilized Cells ◽  
Ethanol Yield ◽  
Continuous Fermentation ◽  
Continuous Process ◽  
Pichia Stipitis ◽  
Batch Process ◽  
Food Grade

One form of economic development efforts for waste utilization in rural communities is to utilize stem sorghum to produce food grade ethanol. Sorghum stem juice with 150 g/L of sugar concentration was fermented using conventional batch process and cell immobilization continuous process with K-carrageenan as a supporting matrix. The microorganism used was Mutated Zymomonas Mobilis to be compared with a mixture of Saccharomyces Cerevisiae and Pichia Stipitis, and a mixture of Mutated Zymomonas Mobilis and Pichia Stipitis. Ethanol in the broth, result of fermentation process, was separated in packed distillation column. Distilate of the column, still contain water and other impurities, was flown into molecular sieve for dehydration and activated carbon adsorption column to remove the other impurities to meet food grade ethanol specification. The packing used in distillation process was steel wool. For batch fermentation, the fermentation using a combination of Saccharomyces Cerevisiae and Pichia Stipitis produced the best ethanol with 12.07% of concentration, where the yield and the productivity were 63.49%, and 1.06 g/L.h, respectively. And for continuous fermentation, the best ethanol with 9.02% of concentration, where the yield and the productivity were 47.42% and 174.27 g/L.h, respectively, is obtained from fermentation using a combination of Saccharomyces Cerevisiae and Pichia Stipitis also. Fermentation using combination microorganism of Saccharomyces Cerevisiae and Pichia Stipitis produced higher concentration of ethanol, yield, and productivity than other microorganisms. Distillation, molecular sieve dehydration and adsorption process is quite successful in generating sufficient levels of ethanol with relatively low amount of impurities.

Effect of Sintering Temperature on the Mechanical Properties of Nanostructured Ceria-Zirconia Prepared by Colloidal Process

2015 ◽  
Vol 1125 ◽  
pp. 401-405
Author(s):  
Mohamed M. Aboras ◽  
Andanastuti Muchtar ◽  
Noor Faeizah Amat ◽  
Che Husna Azhari ◽  
Norziha Yahaya
Keyword(s):  
Mechanical Properties ◽  
Sintering Temperature ◽  
Slip Casting ◽  
Tetragonal Zirconia ◽  
Cold Isostatic Pressing ◽  
Sintering Process ◽  
Colloidal Processing ◽  
Tooth Color ◽  
Biological Compatibility ◽  
Nanostructured Ceria

The demand for tetragonal zirconia as a dental restorative material has been increasing because of its excellent mechanical properties and resemblance to natural tooth color, as well as its excellent biological compatibility. Cerium oxide (CeO2) has been added to yttria-stabilized zirconia (Y-TZP), and studies have demonstrated that the stability of the tetragonal phase can be significantly improved. Y-TZP with 5wt% CeO2 as a second stabilizer was developed via colloidal process, followed by a suitable sintering process. According to the literature, the sintering process is the most crucial stage in ceramic processing to obtain the most homogeneous structure with high density and hardness. This study aims to investigate the effect of sintering temperature on the mechanical properties of nanostructured ceria–zirconia fabricated via colloidal processing and slip casting process with cold isostatic pressing (CIP). Twenty-five pellet specimens were prepared from ceria–zirconia with 20 nm particle size. CeO2 nanopowder was mixed with Y-TZP nanopowder via colloidal processing. The consolidation of the powder was done via slip casting followed by CIP. The samples were divided into five different sintering temperatures with. Results from FESEM, density and hardness analyses demonstrated statistically significant increase in density and hardness as the sintering temperature increased. The hardness increased from 4.65 GPa to 14.14 GPa, and the density increased from 4.70 to 5.97 (g/cm3) as the sintering temperature increased without changing the holding time. Sintering Ce-Y-TZP at 1600 °C produced samples with homogenous structures, high hardness (14.14 GPa), and full densification with 98% of the theoretical density.

Uncertainty and Velocity

2016 ◽  
Author(s):  
Martin Shubik ◽  
Eric Smith
Keyword(s):  
Financial Markets ◽  
Stochastic Analysis ◽  
Control Mechanisms ◽  
Qualitative And Quantitative ◽  
Monetary Systems ◽  
Monetary Economy ◽  
Velocity Of Money ◽  
Quantitative Properties ◽  
Complex Features ◽  
And Control

In this chapter the two features of uncertainty and the variability of the velocity of money are considered. Both of these are fundamental to considering the more subtle features of a monetary economy. They are interlinked and both add further complex features to the information, perception and control mechanisms of modern monetary systems. There has been an explosive development in the study of both the qualitative and quantitative properties of risk. The power of careful modeling and sophisticated stochastic analysis has already shown itself in the context of the stockmarket and other financial markets, but as the various qualitative aspects of risk are being uncovered and made well-defined, the scope of a useful econo-physics stretches far beyond the confines of the dynamics of paper traded on paper in the financial markets to the broad control mechanisms of the economy as a whole.

Volatile compounds in pine stands suffering from pine wilt disease: qualitative and quantitative evaluation

Nematology ◽  
2006 ◽  
Vol 8 (6) ◽  
pp. 869-879 ◽  
Author(s):  
Kazuyoshi Futai ◽  
Natsumi Kanzaki ◽  
Yuko Takeuchi
Keyword(s):  
Volatile Compounds ◽  
Pine Wilt Disease ◽  
Bursaphelenchus Xylophilus ◽  
Wilt Disease ◽  
Economic Damage ◽  
Qualitative And Quantitative ◽  
Pine Wilt ◽  
Pine Trees ◽  
Quantitative Properties ◽  
Pine Stands

AbstractPine wilt disease causes ecological and economic damage in Japanese pine forests in spite of intensive effort to protect them from the pine wood nematode, Bursaphelenchus xylophilus. Pine trees infected with B. xylophilus emit a characteristic bouquet of volatile compounds bioactive to the vector beetle of the nematode, Monochamus alternatus, and potentially affecting symptom development inside the trees. To investigate the qualitative and quantitative properties of volatile compounds in the field, we profiled the volatile emissions in two Japanese black pine stands, one naturally suffering from pine wilt disease and the other artificially inoculated with B. xylophilus. In both pine stands, the emission of some terpenoids from the infected trees such as (−)-α-pinene, began to increase in summer, overlapping the oviposition season of the vector beetle, but peaked in the summer and autumn. These data suggest that the beetles may not necessarily depend on the tremendous quantity of volatiles alone when they search for suitable trees on which to oviposit.

scholarly journals Determination of Chemical Composition and Antimicrobial Activity of Melaleuca cajuputi Essential Oil from Quang Tri Province, Vietnam

2020 ◽  
Vol 32 (9) ◽  
pp. 2203-2207
Author(s):  
TRAN QUOC TOAN ◽  
LAI PHUONG PHUONG THAO ◽  
NGUYEN QUYET CHIEN ◽  
NGUYEN THI HONG VAN ◽  
ÐOAN LAN PHUONG ◽  
...  
Keyword(s):  
Essential Oil ◽  
Maximum Yield ◽  
Batch Process ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Qualitative And Quantitative ◽  
Melaleuca Cajuputi ◽  
Main Components ◽  
Bactericidal Agent

The essential oil of Melaleuca cajuputi was obtained by hydrodistillation method. This work aims to adopt water as a solvent in a batch process to extract essential oil from Melaleuca cajuputi fresh leaves. The leaves are collected from Quang Tri Province, Vietnam. Analysis of constituents was performed by GC/MS. The maximum yield ranged from 0.6 to 0.7%. Several compounds have been identified in high quantities and meaningful qualitative and quantitative differences have been observed under different conditions. The main components of the M. cajuputi essential oil included eucalyptol (27.512%), γ-terpinene (8.59%), terpinolene (9.047%), β-eudesmene (3.359%), α- selinene (3.889%), α-terpineol (4.108%), 1R-α-pinene (2.158%), caryophyllene (6.48%) and α-caryophyllene (3.522%). This study has confirmed that the essential oil of M. cajuputi essential oil is a promising bactericidal agent on several Gram-positive and Gram-negative bacteria.

Performance Improvement of (La,Sr)MnO3 and (La,Sr)(Co,Fe)O3-Type Anode-Supported SOFCs

2006 ◽  
Vol 3 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Vincent A. C. Haanappel ◽  
Josef Mertens ◽  
Andreas Mai
Keyword(s):  
Electrochemical Performance ◽  
Performance Improvement ◽  
Sintering Temperature ◽  
High Reliability ◽  
Single Cells ◽  
Tape Casting ◽  
Slip Casting ◽  
Production Costs ◽  
Processing Route ◽  
Functional Layer

Targets in the development of anode-supported or planar solid oxide fuel cells (SOFCs) are low operation temperatures, high durability, high reliability, high power density, and low production costs. During the past ten years steps have already been taken at Forschungszentrum Jülich to lower the operating temperatures while maintaining the power output. This was achieved by optimizing processing and microstructural parameters of the electrodes. This paper presents the latest results concerning performance improvement through variations of the processing route and the microstructure of La0.65Sr0.3MnO3 (LSM) and La0.58Sr0.4Co0.2Fe0.8O3−δ (LSCF)-type SOFCs. In the case of the LSM-type single cells, the following aspects relating to the electrochemical performance were investigated in more detail: (1) production of the anode substrate by tape casting versus warm pressing; (2) deposition of the anode functional layer (AFL) and electrolyte by screen printing versus vacuum slip casting; (3) use of noncalcined and non-ground YSZ for applying the cathode functional layer (CFL); and (4) sintering temperature of the CFL and cathode current collector layer (CCCL). In the case of LSCF-type cells, a systematic approach was initiated for optimizing the Ce0.8Gd0.2O2−δ (CGO) diffusion barrier layer: (1) deposition techniques of the CGO layer and (2) sintering temperature of the screen-printed CGO layer. Results have shown that certain modifications of the processing route led to a slightly lower electrochemical performance, whereas others did not affect the performance at all. Regarding LSCF-type SOFCs, a slight improvement of the performance was achieved by optimizing the sintering temperature of the CGO layer.

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