Obtainment of Porous Ceramic Structures: A Comparison among Different Compositions and Methods of Conformation

2018 ◽  
Vol 912 ◽  
pp. 224-229
Author(s):  
Lisandro Simão ◽  
Débora Cristina Niero Fabris ◽  
Morgana de Medeiros Machado ◽  
Rafael Caldato ◽  
Murilo Daniel de Mello Innocentini ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Calcium Carbonate ◽  
Porous Ceramic ◽  
Slip Casting ◽  
Sintering Behavior ◽  
X Ray ◽  
Heat Treated ◽  
Porosity And Permeability ◽  
Comparative Results

This paper presents comparative results concerning to the obtaining of porous ceramic structures obtained by pressing, slip casting and polymeric sponge method. Three compositions were prepared, using calcium carbonate as pore-generating agent and characterized by X-ray fluorescence, thermogravimetric analysis and determination of sintering behavior. Each formulation was wet mixed and dried. Then, each formulation was formed by each one of the investigated methods. The obtained samples were dried and heat treated with the appropriate heating rate for calcium carbonate degasification and sintered at 900, 1100 and 1180 °C. The sintered samples were characterized by determination of porosity, crystalline phases formed, compressive strength and permeability. Results showed that porosity and permeability depends strongly on the composition and used conformation method.

An Improvement in Sintering Property of β-Tricalcium Phosphate by Addition of Calcium Pyrophosphate and Calcium Carbonate

2005 ◽  
Vol 475-479 ◽  
pp. 2359-2362 ◽  
Author(s):  
Xin Long Wang ◽  
Hong Song Fan ◽  
Xing Dong Zhang
Keyword(s):  
Phase Transition ◽  
Compressive Strength ◽  
Calcium Carbonate ◽  
Tricalcium Phosphate ◽  
Degradation Rate ◽  
Calcium Pyrophosphate ◽  
Sintering Behavior ◽  
Second Phase ◽  
Lower Temperature

b-tricalcium phosphate(TCP, Ca3(PO4)2) ceramics are preferred as a bioceramics because of its chemical stability and reasonable degradation rate in vivo, but it is difficult to obtain b-TCP ceramics with high compressive strength at lower temperature than that of phase transition to a-TCP. In this study, the sintering behavior of TCP, Ca2P2O7-doped TCP, and CaCO3-doped TCP in the range of 2wt%~5wt% were investigated respectively. Phase transition of pure TCP took place between 1100°C to 1150°C, and pure b-TCP ceramics could achieve a compressive strength of only 3MPa. However, calcium pyrophosphate (CPP, Ca2P2O7) additive prevented the transformation of b-TCP to a-TCP, but the second phase of CPP was observed in the resultant ceramics. Phase transition of TCP ceramics by addition of both CPP and calcium carbonate (CC, CaCO3) took place between 1200°C to 1250°C and the resultant TCP ceramics had few impurity of CPP. By adding CPP and CC to TCP, final ceramics with compressive strength over 12MPa could be obtained when sintered at 1200°C for 2hrs.

Quantitative Determination by X-Ray Diffractometry of Calcium Sulfate and Calcium Carbonate in Airborne Dusts

1988 ◽  
Vol 3 (2) ◽  
pp. 86-90 ◽  
Author(s):  
Toshihiro Nakamura
Keyword(s):  
Calcium Carbonate ◽  
Calcium Sulfate ◽  
Mutual Interference ◽  
Half Width ◽  
Linear Calibration ◽  
X Ray ◽  
Relative Standard ◽  
Diffraction Peaks ◽  
The Difference

AbstractA quantitative simultaneous determination method by X-ray powder diffractometry is described for calcium sulfate and calcium carbonate in airborne dusts. In order to eliminate the mutual interference among diffraction peaks, and to avoid the presence of the hydration isomers of calcium sulfate, dust samples were heated at 350°C for 2 h. To reduce the errors due to the difference-in crystallinity between the standard materials and the samples, the synthesized calcium sulfate anhydrate (anhydrite) was heated to such an extent that the half-width of the 002,020 peak was identical with that of the anhydrite in pretreated dust samples. Standard calcium carbonate (calcite) was ground until the half-width and the orientation index of the 104 peak of calcite was identical with that of the calcite in dust samples. Linear calibration curves were obtained throughout the range of 0 ∼ 30 wt% for anhydrite and the range of 0 ∼ 10 wt% for calcite, respectively. The determination limits were 0.2 wt% for anhydrite and 0.3 wt% for calcite. Relative standard deviations were 3.4 % for 8.0 wt% of anhydrite and 1.8% for 5.4 wt% of calcite. The present method is applicable to determination of calcium sulfate and calcium carbonate in actual dust samples.

scholarly journals Porous Ceramics Membrane Preparation from Ternary Mixtures of Ranong Kaolin, Calcium Carbonate and Silica

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
B. Darunee ◽  
C. Nucharee ◽  
B. Tripob
Keyword(s):  
Calcium Carbonate ◽  
Bending Strength ◽  
Pure Water ◽  
Porous Ceramic ◽  
Water Flux ◽  
Slip Casting ◽  
Weight Fraction ◽  
Porous Ceramics ◽  
Ternary Mixtures ◽  
Casting Technique

Porous ceramics membranes were prepared from ternary mixtures of Ranong kaolin, calcium carbonate and silica using slip casting technique. Totally 10 different composition mixtures were selected from the ternary diagram of CaCO3 : SiO2 : Clay with weight fraction of 0–0.19 : 0.28–0.47 : 0.52–0.71, respectively. The ceramic paste was first fired at 800°C and then sintered at temperatures of 1200, 1250 and 1300°C. The results show that firing temperature above 1200°C is probably too high to prepare the porous ceramics of the studied compositions. The porosity less than 26% is obtained from the samples sintered at 1250–1300°C. The highest porosities of more than 40% are observed from the samples sintered at 1200°C with the weight fraction of clay, calcium carbonate and silica between 0.524–0.562, 0.076–0.152, and 0.310–0.394, respectively. In this range of compositions, the linear shrinkage and water absorption is about 3% and 22%, respectively, while the bending strength is between 28–30 MPa. The pure water flux of samples prepared from mixture formula 9 sintered at 1200°C ranges between 52.4 and 368.8 L/m2.h at the operating pressures 30–120 kPa, indicating that the mixture compositions nearby the formula 9 are the best for porous ceramic production using Ranong kaolin.

scholarly journals Exothermic synthesis of ceramic materials based on barium and strontium aluminosilicates

2021 ◽  
pp. 57-64
Author(s):  
K.B. Podbolotov ◽  
◽  
A.T. Volochko ◽  
G.V. Lisachuk ◽  
R.V. Krivobok ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Compressive Strength ◽  
Loss Tangent ◽  
Ceramic Materials ◽  
X Ray ◽  
High Refractoriness ◽  
Heat Treated ◽  
Protective Structures ◽  
Synthesized Materials ◽  
Rocket Technology

Ceramic materials were synthesized in the RO(R=Ba, Sr)–Al2O3–SiO2 system using exothermic synthesis from solutions containing barium and strontium nitrates, silica and organic reducing agents (glycine and carbamide). It was shown that only the use of a mixture of glycine and carbamide as well as the addition of ammonium nitrate allows carrying out a complete exothermic synthesis with the formation of an X-ray amorphous product with a small fraction of the crystalline phase. It was established that monophase materials based on barium and strontium aluminosilicates (BaAl2Si2O8 and SrAl2Si2O8) are formed when the obtained X-ray amorphous product is heat-treated at the temperatures above 10000C. Ceramics from synthesized materials sintered at 15500C has a high refractoriness, open porosity of 0–1.0%, compressive strength of 115–120 MPa; dielectric constant of 3.25–6.0 (at the frequency of 1 MHz) and the loss tangent of (1.5–5.2)10–3. The results shows that the exothermic synthesis ensures the preparation of nano- and sub-microcrystalline powders in the system RO(R=Ba, Sr)–Al2O3–SiO2. Materials based on the obtained aluminosilicates can be used in the manufacture of protective structures for devices operating in the radio frequency band, in radar installations of aviation and rocket technology, in microwave elements, etc.

Quantitative Phases Determination of Zirconia Ceramics via Rietveld Method

2010 ◽  
Vol 660-661 ◽  
pp. 989-994
Author(s):  
R.A. Muñoz ◽  
J.E. Rodriguez ◽  
C. Santos ◽  
Cosme Roberto Moreira Silva
Keyword(s):  
Rietveld Method ◽  
Ceramic Powder ◽  
Industrial Applications ◽  
Zirconia Ceramic ◽  
Zirconia Ceramics ◽  
Excellent Thermal Stability ◽  
X Ray ◽  
Heat Treated ◽  
Pechini Process

Industrial applications of partially stabilized zirconia (PSZ) has increased substantially recently, considering its excellent thermal stability, strength and ionic conductibility. Its main application includes oxygen sensors and fuel cells. In this work zirconia ceramic powder is produced by Pechini process, mixing citric acid and ethylene glycol, adding yttrium and zirconium precursors. All the process was carried out with complete agitation. The obtained powder after this procedure is heat treated at 650°C during two hours. Characterization was performed by infra-red spectroscopy, x-ray diffractometry and quantitative analysis by Rietveld Method. The results show tetragonal and monoclinic phases, with nanometric crystallite.

The determination of the calcite : aragonite ratio in mollusc shells by X-ray diffraction

1963 ◽  
Vol 33 (262) ◽  
pp. 608-612 ◽  
Author(s):  
T. T. Davies ◽  
P. R. Hooper
Keyword(s):  
Calcium Carbonate ◽  
Line Intensity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Intensity ◽  
Carbonate Shell ◽  
Grinding Operations ◽  
Mollusc Shells

SummaryBy measuring the integrated line intensity on a Philips' X-ray diffractometer in place of the peak intensity and by paying due regard to the ease with which aragonite converts to calcite during cleaning and grinding operations, the proportion of calcite and aragonite in a pure calcium carbonate shell can be determined to within 1% of the total in less than 30 minutes.

Porous Ceramic Structures Obtained from Calcium Carbonate as Pore Generating Agent

2014 ◽  
Vol 775-776 ◽  
pp. 755-760 ◽  
Author(s):  
Lisandro Simão ◽  
Oscar Rubem Klegues Montedo ◽  
Rafael Caldato ◽  
Murilo Daniel de Mello Innocentini ◽  
Marcos Marques da Silva Paula ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Heating Rate ◽  
Ball Mill ◽  
Sintering Temperature ◽  
Porous Ceramic ◽  
Hydraulic Press ◽  
Experimental Results ◽  
Crystalline Phases ◽  
Heat Treated

The aim of this work is to present experimental results related to the use of calcium carbonate as pore generating agent. Four compositions containing 20 wt.% of limestone were used and characterized chemically and thermally. Each composition was homogenized in a porcelain ball mill, dried in a laboratory drier, humidified at 7 wt.%, and pressed in an uniaxial hydraulic press. Compacted samples were dried and heat treated with a suitable heating rate for the degasification of calcium carbonate and sintered at 800, 900, and 1050 °C. Sintered samples were characterized to determine the porosity, crystalline phases formed and microstructural features. The results showed that the porosity has increased with the sintering temperature of the compositions increasing due porosity generated by the calcium carbonate degasification and the material expansion.

scholarly journals A new approach for the determination of multiple cation locations and ordering, using the example of natural and heat-treated columbites

2011 ◽  
Vol 44 (4) ◽  
pp. 738-746 ◽  
Author(s):  
E. J. Kinast ◽  
O. Isnard ◽  
J. B. M. da Cunha ◽  
M. A. Z. de Vasconcellos ◽  
C. A. dos Santos
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
New Approach ◽  
X Ray ◽  
Type Compound ◽  
Natural Minerals ◽  
Heat Treated

A new approach is proposed to determine unambiguously the location of four cations within the crystal structure of a naturalAB2O6columbite-type compound and derivatives, when submitted to order–disorder transitions caused by heat treatments. This method is based on the successive use of electron microprobe analysis to determine the cation concentration, Mössbauer spectroscopy to identify the Fe occupation, and a crystal structure determination of the samples combining Rietveld refinements of both neutron and X-ray diffraction. This approach is tested successfully to investigate (Fe, Mn, Nb, Ta) natural minerals as well as oxides obtained by heat treatment of the initialAB2O6columbite-type compound.

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