Effect of TiO2 on mullite formation in mixture of Nigeria sourced kaolinite and calcined alumina

In this study, the effect of TiO2 when added to a mixture of Nigerian sourced of kaolin and calcined alumina powder (50:50) was investigated. The influence of Ti4+ ion on the physico-mechanical property (apparent porosity, bulk density and modulus of rupture), phase and microstructural evolution was studied at sintering temperature of 1600?C when mullitisation has been maximized based on previous reports. The sintered samples showed considerably high porosity of about 16 %, a slight reduction of about 5 % in porosity was observed on TiO2 addition. There was no appreciable change in the bulk density due to TiO2 doping, but the modulus of rupture (MOR) reduced appreciably from 43 MPa to 36 MPa on TiO2 doping. As shown by the XRD, mullite was seen as the major phase with negligible cristobalite phase for the undoped sample. The TiO2 doped sample displayed mullite as major and corundum as minor phases. There appeared more mullite phases in the doped sample than the undoped sample indicating a higher percentage of mullite formation. The microstructural study shows the presence of acicular mullite with round edges and good aspect ratio. The presence of inter-granular and intra-granular pores in TiO2 doped samples might have contributed to the reduction in strength observed at 1600?C.

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Effects of Al2O3 Species and Particle Sizes on Properties of Al2O3-Cr2O3 Refractories

Materials Science Forum ◽

10.4028/www.scientific.net/msf.745-746.610 ◽

2013 ◽

Vol 745-746 ◽

pp. 610-615

Author(s):

Hong Gang Sun ◽

Peng Tao Li ◽

Shuang Zhi Yan ◽

Gang Wang ◽

Jian Qiang Li ◽

...

Keyword(s):

Pore Size ◽

Bulk Density ◽

Size Distribution ◽

Modulus Of Rupture ◽

Alumina Powder ◽

Particle Sizes ◽

Activated Alumina ◽

Bimodal Size Distribution ◽

Lower Porosity ◽

Shock Resistance

The microstructure of Al2O3-Cr2O3 refractories is an important factor to affect its high temperature performance. The Al2O3-Cr2O3 green bodies were prepared by hot pressing using aluminum oxide and Cr2O3 powder mixture by adding a binder. And then the specimens were sintered at 1650 for 4h in the electric muffle furnace. Properties of specimens with different species of Al2O3 powders were studied, including α-Al2O3 powder, ρ-Al2O3 powder, and fused corundum powder. Moreover, three sizes of α-Al2O3 powder (D50=0.8 μm, 1.4 μm, 4.0 μm) were used as additive. Properties of specimens, including apparent porosity, bulk density, cold modulus of rupture, pore size distribution were tested. The morphology of sintered specimens was analyzed by the Scanning Electron Microscope. The results showed that the specimens adding α-Al2O3 powder had the better properties since α-Al2O3 powder has higher sintering activity, and it was more efficient for Al2O3-Cr2O3 solid solution. The specimens with α-Al2O3 had lower porosity, higher bulk density and cold modulus of rupture, and more uniform pore distribution. There were great differences in sintering activity for specimens with different particle size of α-Al2O3 powder. And the microstructure of Al2O3-Cr2O3 was significantly dissimilar. The specimen with the addition of the activated alumina powder of D50 with the size of 1.4 μm and bimodal size distribution showed the perfect performance, including high density and high flexural strength. The experimental results showed that the microstructure of this specimen was uniform and its pore size was homogeneous. This special microstructure is beneficial for improving the slag resistance and thermal shock resistance of Al2O3-Cr2O3 refractories.

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Thermal insulation properties of green vacuum insulation panel using wood fiber as core material

BioResources ◽

10.15376/biores.14.2.3339-3351 ◽

2019 ◽

Vol 14 (2) ◽

pp. 3339-3351 ◽

Cited By ~ 1

Author(s):

Baowen Wang ◽

Zhihui Li ◽

Xinglai Qi ◽

Nairong Chen ◽

Qinzhi Zeng ◽

...

Keyword(s):

Thermal Conductivity ◽

Bulk Density ◽

Thermal Insulation ◽

Wood Fiber ◽

Core Material ◽

High Porosity ◽

Total Thermal Conductivity ◽

Wood Fibers ◽

Vacuum Insulation ◽

Vacuum Insulation Panel

Wood fibers were prepared as core materials for a vacuum insulation panel (VIP) via a dry molding process. The morphology of the wood fibers and the microstructure, pore structure, transmittance, and thermal conductivity of the wood fiber VIP were tested. The results showed that the wood fibers had excellent thermal insulation properties and formed a porous structure by interweaving with one another. The optimum bulk density that led to a low-cost and highly thermally efficient wood fiber VIP was 180 kg/m3 to 200 kg/m3. The bulk density of the wood fiber VIP was 200 kg/m3, with a high porosity of 78%, a fine pore size of 112.8 μm, and a total pore volume of 7.0 cm3·g-1. The initial total thermal conductivity of the wood fiber VIP was 9.4 mW/(m·K) at 25 °C. The thermal conductivity of the VIP increased with increasing ambient temperature. These results were relatively good compared to the thermal insulation performance of current biomass VIPs, so the use of wood fiber as a VIP core material has broad application prospects.

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Properties of Dan Kwian, Sukhothai and Ratchaburi Pottery Clays Fired at 700 and 900 °C

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.608.47 ◽

2014 ◽

Vol 608 ◽

pp. 47-61

Author(s):

Nonglak Meethong ◽

Wanwisa Pattanasiriwisawa ◽

Weenawan Somphon ◽

Waraporn Tanthanuch ◽

Sutham Srilomsak

Keyword(s):

Specific Gravity ◽

Comparative Study ◽

Water Absorption ◽

Bulk Density ◽

Firing Temperature ◽

Reflectance Spectra ◽

Modulus Of Rupture ◽

Regression Equations ◽

Statistical Software

Dan Kwian, Sukhothai and Ratchaburi pottery clays are economically important pottery clays. They are well known in the Thai ceramic society for making Dan Kwian pottery, Sawankhalok pottery and Dragon jars, respectively. There have been several studies of these pottery clays. However, few of them used statistics to analyze their results. This work is a comparative study of the compositions and properties of these three pottery clays using statistical software to analyze the results. Results show that the major components of these pottery clays are SiO2 and Al2O3. The Modulus of Rupture (MOR) of each pottery clay fired at 700°C are not significantly different. Sukhothai pottery clay fired at 900°C has a higher MOR and bulk density while its porosity, water absorption and apparent specific gravity are less than those of the Dan Kwian and Ratchaburi pottery clays fired at the same temperature. Additionally, the current study developed regression equations for estimating the properties of all pottery clays under study. Finally, it was found that the L*, a*, b* and reflectance spectra of all pottery clays increased when firing temperature was increased from 700 to 900°C.

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EVALUATION OF THE WINDALIA SAND, BARROW ISLAND AN EMPIRICAL APPROACH

The APPEA Journal ◽

10.1071/aj69014 ◽

1970 ◽

Vol 10 (1) ◽

pp. 91 ◽

Cited By ~ 1

Author(s):

J. W. Burdett ◽

J. C. Parry ◽

S. P. Willmott

Keyword(s):

Bulk Density ◽

Transit Time ◽

Evaluation Method ◽

Water Saturation ◽

Drilling Fluid ◽

Empirical Evaluation ◽

High Porosity ◽

Fluid Density ◽

Injection Wells ◽

Standard Format

The Barrow Island oilfield derives 97 percent of its 46,000 barrels per day production from the Lower Cretaceous Windalia Sand. The lithology of the sand, which is 110' + 20' thick across the field, is very finegrained, glauconitic sandstone, shaly and silty in parts and varying from moderately unconsolidated to firm. Thin, hard beds of dolomitic and calcareous, sandstone occur throughout. The sand has high porosity and low permeability.The argillaceous and unconsolidated nature of the formation precludes the use of log interpretation methods based on standard parameters, and it was decided to develop an empirical log evaluation method. In order to calibrate the logs, sixteen of the early wells were fully cored and logged, and the data compared using the Holgate method, which allows two parameters to be correlated to determine their relationship. In the example which is the subjert of this paper, core porosity was correlated against both sonic transit time and bulk density and hence calibration of these log parameters was obtained.The best fit straight line relating porosity and sonic transit time has its origin at 76 microseconds per foot and extrapolates to 246 microseconds per foot at 100 percent porosity. The bulk density — porosity cross plot gives a grain density of 2.71 grams per cubic centimetre and fluid density of 1.16 grans/ cc. The deviations from the standard parameters of delta-t matrix = 56. delta-t fluid = 189, grain density = 1.65, fluid density = 1.0 are explained by the shaliness and lack of compaction of the formation. Using charts for the calculation of water saturation and porosity from induction conductivity and sonic transit time (or bulk density) at 2' intervals through the sand, backed up with traced SP and caliper curves, an evaluation plot of standard format is developed. Intervals of nett effective pay are then chosen.Other evaluation techniques used during the development of the Windalia Poo! include a modified movable oil plot, used in the water injection wells where a saturated saline drilling fluid was employed, and a Sonic-Neutron log comparison for the identification of suspected gas columns in the Windalia.440 wells have now been drilled at Barrow Island, and the empirical evaluation methods evolved have enabled the definition of beds of producible hydrocarbons in all cases.

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Effect of MgO/CuO on the Microstructure and Thermal Properties of Cordierite–Alumina Ceramics

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.509.240 ◽

2012 ◽

Vol 509 ◽

pp. 240-244

Author(s):

Li Ying Tang ◽

Xi Cheng ◽

Ping Lu ◽

Fang Yue

Keyword(s):

Thermal Conductivity ◽

Bulk Density ◽

Thermal Shock ◽

Thermal Shock Resistance ◽

Raw Materials ◽

Laser Flash ◽

Alumina Powder ◽

Alumina Ceramics ◽

Conductivity Increase ◽

Shock Resistance

Abstract: Cordierite–alumina ceramics were prepared with the raw materials of cordierite and α-alumina powder, and TiO2，CuO and MgO were added as composite additives. The effect of MgO/ CuO ratios on the microstructure, thermal conductivity and thermal shock resistance of cordierite–alumina ceramics were researched by X-ray diffraction, scanning electron microscopy and laser flash analyzer; the bulk density and the porosity of cordierite – alumina ceramics were measured. The results show that with increasing of MgO/CuO ratios, the bulk density and thermal conductivity increase firstly and then decrease, and have a minimum with 0.4wt% MgO and 0.667 MgO/CuO; and the porosity of ceramics decreases firstly and then increases and has a maximum with 0.4wt% MgO and 0.667 MgO/CuO;There are little changes in the size of the grain of the ceramics, and a small amount of magnesium aluminate spinel precipitate; the thermal shock resistance performance of the ceramics is developed with the increasing of MgO/CuO ratios.

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Limestone Sludge in the Brick Body

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1000.158 ◽

2014 ◽

Vol 1000 ◽

pp. 158-161 ◽

Cited By ~ 1

Author(s):

Radomír Sokolař ◽

Lucie Vodová ◽

Mikuláš Šveda

Keyword(s):

Thermal Conductivity ◽

Water Absorption ◽

Bulk Density ◽

Quartz Sand ◽

Modulus Of Rupture ◽

Firing Process ◽

Brick Clay ◽

Coefficient Of Thermal Conductivity ◽

Washing Process ◽

Firing Shrinkage

Influence of limestone sludge (generated during the washing process of limestone crushed aggregates) with high content of CaO in the form of calcite on the properties of brick body made from non-calcareous sludge (from the washing process of quartz sand) as a basic plastic brick clay was determined. Presence of calcite very distinctly influenced the firing process and properties of fired body. Limestone sludge decreases firing shrinkage, bulk density and coefficient of thermal conductivity of the brick body after the firing in the range of 850 – 950 °C. Higher modulus of rupture and water absorption is typical for fired bodies with limestone sludge addition. Most of these improvement are caused by the formation of anorthite only in the bodies based on the limestone sludge.

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Tailoring the strength and porosity of rapid-hardening magnesia phosphate paste via the pre-foaming method

Scientific Reports ◽

10.1038/srep13016 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 1

Author(s):

Li-Jie Liu ◽

Jin-Hong Li ◽

Xiang Wang ◽

Ting-Ting Qian ◽

Xiao-Hui Li

Keyword(s):

Compressive Strength ◽

Porous Structure ◽

Bulk Density ◽

Sodium Silicate ◽

Average Pore Size ◽

Hydration Product ◽

Polypropylene Fibers ◽

High Porosity ◽

Average Pore ◽

Maximum Compressive Strength

Abstract High-porosity magnesia phosphate paste (HPMPP) was prepared via the pre-foaming method. In the pre-foaming method, sintering treatment was not required. The bulk density and maximum compressive strength of the HPMPP prepared according to the ratio of water to solids (W/So) of 0.32 reached 464.00 ± 5.00 Kg/m3 and 0.30 ± 0.05 MPa, respectively. The compressive strength increased with the increases in the addition amounts of sodium silicate and polypropylene fibers. The bulk density of HPMPP increased with the increase in the addition of sodium silicate and decreased with the increase in the addition of polypropylene fibers. Besides, the porosity of the magnesia phosphate paste increased from 79.85% to 81.27% and from 80.31% to 83.75% after the addition of sodium silicate and polypropylene fibers respectively. The highest porosity (83.75%) of the prepared HPMPP was realized under the addition proportion (sodium silicate: polypropylene fibers: solids = 0.06:0.0025:1). The average pore size of the prepared HPMPP is about 180 μm and the pore distribution range is relatively narrow. The hydration product (struvite) is combined with MgO particle one by one and then coated on the surface of bubbles. With the decrease of the water content, after breaking bubbles, the porous structure can be achieved.

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Magnesia-zircon brick: Evolution of microstructure, properties and performance with increasing sintering temperature

Science of Sintering ◽

10.2298/sos1302181g ◽

2013 ◽

Vol 45 (2) ◽

pp. 181-188

Author(s):

J. Gao ◽

Z. Guo ◽

L. Wang ◽

W. Jiang

Keyword(s):

Bulk Density ◽

Microstructural Evolution ◽

Creep Resistance ◽

Sintering Temperature ◽

Modulus Of Rupture ◽

Crushing Strength ◽

Cold Crushing Strength ◽

And Performance ◽

Evolution Of Microstructure ◽

Font Color

Depending on phase components and densification, Magnesia-Zircon brick varies in appearance from white to veined and then brown with increasing sintering temperature. Properties including bulk density, apparent porosity and hot modulus of rupture as well as performance embodied with creep resistance and refractoriness continue to improve with sustaining enhancement of sintering temperature. Exceptionally, cold crushing strength first increases then decreases with rising sintering temperature and a peak exists at 1550oC. Microstructural evolution suffers zircon decomposition companying by silica escape, forsterite formation, matrix solidification and zirconia coagulation, until a zirconia/forsterite composites belt tightly coating on magnesia aggregates. Excessive coagulation of zirconia caused by oversintering probably results in microcracks formation and defects enlargement thereby degrades cold crushing strength. This article has been retracted. Link to the retraction <a href="http://dx.doi.org/10.2298/SOS1303387E">10.2298/SOS1303387E</a>

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Effects of Monoclinic ZrO2 with Different Particle Size on Properties of Zirconia Refractories

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.335-336.721 ◽

2011 ◽

Vol 335-336 ◽

pp. 721-727

Author(s):

Hong Gang Sun ◽

Shuang Zhi Yan ◽

Peng Tao Li ◽

Qing Hua Tan ◽

Ai Jun Wu

Keyword(s):

Particle Size ◽

Phase Composition ◽

Grain Boundaries ◽

Bulk Density ◽

Modulus Of Rupture ◽

Monoclinic Zirconia ◽

Stabilized Zirconia ◽

Zirconia Powder ◽

Partially Stabilized Zirconia ◽

The Matrix

The zirconia refractories were prepared using partially stabilized zirconia grain and monoclinic zirconia powder as the matrix, partially stabilized zirconia particles as the aggregate, and phenolic resin as the binder, and four sizes of monoclinic zirconia powder (D50=1 μm, 3 μm, 6 μm, 10 μm) were used as additives. Besides, an improved specimen was prepared using a specific monoclinic zirconia powder as additive. Properties of specimens with different sizes of m-ZrO2powders were researched, including apparent porosity, bulk density, cold modulus of rupture, pore size distribution. Moreover, phase composition and microstructure were analyzed. The results show that, particle size of monoclinic zirconia powders greatly affect the sintering of materials. The specimens with finer m-ZrO2powder have lower porosity, higher bulk density and cold modulus of rupture, and the grain boundaries of zirconia particles were fuzzy, showing that the matrix of the specimens were almost sintered completely. While in specimens using coarser m-ZrO2powder, the grain boundaries of zirconia particles were clear, showing that the matrix of the specimens were not sintered completely.. Though finer monoclinic zirconia powder promoted the sintering of materials in the test, it had negative impact on the microporus structure, for large pores were observed in the specimen with fine m-ZrO2powder. Finally, the improved specimen with promoted sintering and optimized microstructure as well as phase composition was obtained by using specific monoclinic zirconia powder as additive.

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Influence of Structure-Directing Additives on the Properties of Poly(methylsilsesquioxane) Aerogel-Like Materials

Gels ◽

10.3390/gels5010006 ◽

2019 ◽

Vol 5 (1) ◽

pp. 6 ◽

Cited By ~ 1

Author(s):

Marta Ochoa ◽

Alyne Lamy-Mendes ◽

Ana Maia ◽

António Portugal ◽

Luísa Durães

Keyword(s):

Specific Surface ◽

Bulk Density ◽

Surface Area ◽

Specific Surface Area ◽

High Porosity ◽

Poly Ethylene Glycol ◽

Optimum Amount ◽

Molar Ratios ◽

Fine Control ◽

Poly Ethylene

The effect of glycerol (GLY) and poly(ethylene glycol) (PEG) additives on the properties of silica aerogel-like monoliths obtained from methyltrimethoxysilane (MTMS) precursor was assessed. The tested molar ratios of additive/precursor were from 0 to 0.1 and the lowest bulk densities were obtained with a ratio of 0.025. When a washing step was performed in the sample containing the optimum PEG ratio, the bulk density could be reduced even further. The analysis of the material’s microstructure allowed us to conclude that GLY, if added in an optimum amount, originates a narrower pore size distribution with a higher volume of mesopores and specific surface area. The PEG additive played a binder effect, leading to the filling of micropores and the appearance of large pores (macropores), which caused a reduction in the specific surface area. The reduction of the bulk density and the microstructural changes in the aerogels induced by adding a small amount of these additives confirm the possibility of fine control of properties of these lightweight materials. The achieved high porosity (97%) and low thermal conductivity (~35 mW·m−1·K−1) makes them suitable to be used as thermal insulators.

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