Apparent Porosity Values Research Articles

Synthesis of a ceramic tile base based on high-alumina fly ash

To effectively utilize the industrial waste of high-alumina fly ash (HAFA), a ceramic tile base was successfully synthesized by the ceramic sintering process. In this research, the influence of HAFA addition and sintering temperature on properties were investigated. The results showed that the presence of ferruginous and calcareous minerals in HAFA decreased the inversion temperature of densification. Moreover, the optimum parameters were obtained at the sintering temperature of 1300°C for 2h with 70% HAFA, 15% clay and 15% quartz. In this research, the highest flexural strength reaches 67MPa, and the corresponding bulk density and apparent porosity values are 2.43g/cm3 and 0.13%, respectively.

Geological and geomechanical properties of the carbonate rocks at the eastern Black Sea Region (NE Turkey)

Turkey located in the Alpine-Himalayan Mountain Belt has 35% of the natural stone reserves of the world and has good quality marble, limestone, travertine and onyx reserves especially in the western regions of the country. The eastern Black Sea Region with a 1.4 million meters cubes reserve has a little role on the natural stone production in the country. For this reason, this paper deals with investigation on the potential of carbonate stone in the region and determination of the geological and geo-mechanical properties of these rocks in order to provide economic contribution to the national economy. While the study sites are selected among the all carbonate rock sites, the importance as well as the representative of the sites were carefully considered for the region. After representative samples were analyzed for major oxide and trace element compositions to find out petrochemical variations, the experimental program conducted on rock samples for determination of both physical and strength properties of the carbonate rocks. The results of the tests showed that there are significant variations in the geo-mechanical properties of the studied rock groups. The density values vary from 2.48 to 2.70 gr/cm3, water absorption by weight values range from 0.07 to 1.15% and the apparent porosity of the carbonate rocks are between 0.19 and 3.29%. However, the values of the UCS shows variation from 36 to 80 MPa. Tensile and bending strength values range from 3.2 to 7.5 MPa and 6.0–9.2 MPa respectively. Although the onyx samples have the lowest values of apparent porosity and water absorption by weight, these samples do not have the highest values of UCS values owing to occurrence of the micro-cracks. The UCS values of the rock samples were also found after cycling tests However, the limestone samples have less than 5% deterioration after freezing-thawing and wetting-drying tests, but travertine and onyx samples have more than 15% deterioration. Exception of the apparent porosity values of travertine samples, all geo-mechanical properties of the studied carbonate rocks were determined in the acceptance values given by Turkish Standards Institute (TSE) for using as a natural dimension stone. After these investigations, it is anticipated that in the near future the number of quarries and factories will increase and more types of natural stones will be discovered in the eastern Black Sea Region and thus this will provide economic contribution to the economy of the country.

Research in the Field of Preparing Molded and Unmolded Refractories Based on High-Alumina HCBS. Part 4. Effect of Refractory Clay Additions on Properties of Compound Composition HCBS, Castings, and Materials Based on Them

Examples are provided of the efficiency of adding refractory clays in HCBS technology and ceramic concretes. Properties of castings prepared by slip casting based on HCBS of composite composition in bauxite – very fine quartz glass (VFQG), and additions of refractory clay (1 – 10%) are studied. The effect of continuous nonisothermal heating up to 1500°C on specimen linear dimensions is studied by means of a high-temperature dilatometer. Data obtained are compared with specimen apparent porosity after isothermal firing with soaking for 1 h in the range 800 – 1500°C. Maximum linear shrinkage with nonisothermal heating and minimum value of apparent porosity after isothermal firing correspond to the range 1200 – 1500°C. Maximum indices are noted at 1500°C for both specimen growth and also porosity due to occurrence of secondary mullitization.

Cementitious Composites Reinforced with Kraft Pulping Waste

Kraft pulping is currently the most widely used technique in the production of cellulose pulp, and the production process generates large amount of lignocellulosic residues. Looking to add value to this residue, the aim of this study was to evaluate the physical and mechanical properties of extruded cementitious matrices reinforced with lignocellulosic waste from the kraft pulping of Eucalyptus spp wood. The experimental design were consisted of 3 treatments with 5 samples for each treatment, as follows: 1) 70% Portland cement (by mass) with 30% ground carbonate (by mass) - T1; 2) 66.5% of Portland cement, 28.5% ground carbonate and 5% residual pulp fibers - T2, and 3) 69.5% Portland cement, 25.5% metakaolin and 5% residual pulp fibers - T3. The mass for extrusion was prepared with the addition of hydroxypropyl-methylcellulose (HPMC) and polyether carboxylic (ADVA) as rheology modifiers, with water:cement ratio of around 0.3. After mixing, the mass was taken to an extruder where the specimens were obtained. Apparent porosity (AP), bulk density (BD), water absorption (WA), modulus of rupture (MOR), fracture toughness (KIC) and fracture energy (EF) were evaluated. There was statistical difference between the treatments for AP, BD, WA, KIC and EF values, and the treatment with the metakaolin showed the lowest values for BD and the highest values for AP, WA and FE. The treatment with ground carbonate and residual pulping showed intermediate results when compared to the other treatments. No statistical differences were found between the fiber-cement treatments for MOR values.

Influence of thermal damage on the physical and mechanical properties of carbonate rocks

In this study, physical and mechanical properties of six carbonate rocks (two marbles, two low-porous limestones and two high-porous limestones) were studied under the influence of temperatures ranging from 105 to 600 °C. It was found that the values of bulk density, P wave velocity, uniaxial compressive strength, modulus of elasticity, Brazilian tensile strength and Shore hardness decreased to different extent, whilst apparent porosity increased under the influence of heat up to 600 °C. The results indicated a maximum decrease of 62–82 % in modulus of elasticity and the least reduction of 1.2–2.7 % in bulk density of carbonate rocks. Moreover, the uniaxial compressive strength, Brazilian tensile strength, P wave velocity and Shore hardness values decreased by 27–51, 28–75, 36–69 and 10–40 %, respectively. Moreover, increase in apparent porosity values of tested rocks with very high porosity was the least, whereas the apparent porosity values of low-porous rocks increased up to ten times of initial value.

ZrO2-C계 침지노즐 제조시 상대습도에 따른 바인더용 페놀수지의 영향

The thermodynamic behavior of phenolic resin was investigated to verify the relation between the properties of porous ceramics with ZrO₂-C system for submerged entry nozzle and the characteristics of phenolic resin with various relative humidity. The green and the sintered density were decreased between 25% and 50% relative humidity, whereas they were gradually enhanced above 50% relative humidity. The highest value of apparent porosity was 20.1% and the minimum compressive strength was 69㎫ in the specimen using the powder exposed to 50% relative humidity. As a result of thermal analysis for phenolic resin, the shift of endothermic peak to low temperature and the reduction of exothermic peak were observed, and the peaks corresponded to melting and curing of phenolic resin, respectively. The melting and the curing of phenolic resin generate the change of green density, and it can affect the properties of submerged entry nozzle.

Evaluation of an Advanced Benchtop Micro-Computed Tomography System for Quantifying Porosities and Pore-Size Distributions of Two Brazilian Oxisols

Recent advances in benchtop Micro-Computed Tomography (Micro-CT) provided the motivation to thoroughly evaluate and optimize scanning, image reconstruction/segmentation and pore space analysis capabilities of a SkyScan 1172 Micro-CT system and associated SkyScan Analyzer software package (SkyScan, Belgium). To demonstrate applicability to soil research the project was focused on determination of porosities and pore-size distributions of two Brazilian Oxisols from segmented computed tomography (CT)-data. Effects of metal filters and various acquisition parameters (e.g., total rotation, rotation step, and radiograph frame averaging) on image quality and acquisition time were evaluated. Impacts of sample size and scanning resolution on CT-derived porosities and pore-size distributions were illustrated. Best image quality was achieved when an aluminum/copper filter (0.5/0.04 mm thickness) was positioned between sample and x-ray detector, the sample was rotated 360° in 0.3° steps and the number of averaged projections per rotation step was larger than 15. As with all other CT systems there was a tradeoff between maximum observable sample volume and achievable resolution. Even for soil samples scanned at the highest considered resolution of 3.7 μm (1.0 μm is the maximum achievable resolution) it was apparent that CT-derived porosities vastly underestimated physically measured apparent porosity values. In addition, it was shown that dense mineral particles can be discriminated from slightly attenuating elements and minerals. While image acquisition and reconstruction yielded excellent grayscale CT-data, the supplied software lacked advanced image segmentation algorithms and morphometric pore space analysis capabilities.

Ceramic properties of kaolinized tuffaceous rocks in Kesan region, Thrace, NW Turkey

The Kesan–Karlikoy kaolin occurrence is located in the SW Thrace (Turkey) and was formed by the alteration of tuffaceous rocks. The tuff and tuffaceous units are made up of (1) bentonite, (2) kaolin and (3) zeolite (mordenite-rich), from bottom to top. The 20–40 m thick kaolin level is beige, yellowish and whitish beige in color and sandy tuff in appearance. The alteration of the rock to kaolin was explained by chemical, optical and scanning electron microscope (OM and SEM) and X-ray diffraction (XRD) studies. In terms of mineral constituents, the samples were generally rich in kaolinite and quartz, and some of them contained minor amounts of smectite, feldspar, opal-CT and calcite as well. The kaolinite contents estimated by XRD-modal analysis range between 20 and 55 mass % in the kaolin zone. Representative sample from the kaolin zone was used for ceramic tests. Flexure strength and Young modulus were measured and porosity, bulk density and water absorption were determined. For the samples fired at 1140 °C, the flexure strength was 9.78 MPa. The elasticity modulus was 7.94 GPa. Water absorption and apparent porosity values were 12.7% and 22.9%, respectively. Finally, the apparent density was 2.33 g/cm 3. Plasticity values of kaolin samples were also determined according to the Pfefferkorn plasticity test. The kaolinized tuff can be used for wall tiles, floor tiles, and tableware which are shaped by dry pressing and extrusion.

Investigation of Parameters Affecting Formation of Mullite from Kaolin

This study aims to improve the understanding of formation of mullite from kaolin at low process temperature using different sintering regimes. The optimum parameters affecting mullite formation from kaolin such as sintering temperature (from 1000 to 1500 °C), heating rate (3 and 20 °C min -1 ) and dwell time (3 min, 1 and 5 h) were investigated. There was a marked increase in bulk density values with increasing sintering temperature up to ~1300 °C, resulting in a significant decline at the apparent porosity values. The lower heating rate and the longest dwell time appeared to be more effective to obtain a maximum density value at 1300 °C. Microstructural features were examined using SEM, and the nature of crystalline phases present was confirmed by XRD analysis. It was observed that formation of mullite grains started at ~1100 °C. Although there was a significant amount of mullite grains at 1200 °C, completely elongated mullite crystals were formed at 1300 °C.

Synthesis and characterization of La0.9Sr0.1Ga0.8Mg0.2O3-δ electrolyte for intermediate temperature solid oxide fuel cells (ITSOFC)

Experimental investigations on new materials for application as electrolyte in electrolyte supported planar Intermediate Temperature Solid Oxide Fuel Cells (ITSOFC) operating below 800 °C is in progress at our laboratory. Sr and Mg doped Lanthanum gallate (LSGM) powder was prepared by glycine — nitrate combustion method. The prepared LSGM powder is relatively finer than that prepared through other techniques such as solid-state reaction. The measurements comprising XRD, particle size, density, TGA/DTA were made. Thin sections of circular pellets were fabricated and annealed at different temperatures ranging between 1000 and 1300 °C. The sintering behaviour of LSGM was investigated to obtain information on the densification factor, relative percentage shrinkage/expansion in volume, while annealing and the resulting apparent porosity values. Bismuth oxide is found to be an effective sintering aid in general. So the effect of bismuth oxide addition on LSGM was investigated through sintering studies, XRD, TGA/DTA, SEM and conductivity measurements. The results obtained on LSGM with and without bismuth oxide addition are discussed with respect to the requirement of an electrolyte for ITSOFC applications.

Interactions between an ABS type leadless glaze and a biscuit fired bone china body during glost firing. Part I: preparation of experimental phases

Abstract In this paper, part of an extended study, crystalline phases of a biscuit fired bone china body, namely anorthite and beta-tricalcium phosphate (β-TCP), were produced experimentally to be used in subsequent interface studies for simulation of the interactions during glost firing at different temperatures between an ABS type commercial leadless glaze and the individual phases originally present in the body. The research was undertaken based on the premise that bone china has been a product providing the greatest challenge in moving to a totally leadless glaze. High bulk density and low apparent porosity values were achieved from both the anorthite and β-TCP samples through the suitable heat treatments. The microstructural and chemical characteristics of the experimental phases were studied using X-ray diffraction (XRD), scanning (SEM), and transmission (TEM) electron microscopy techniques in combination with EDS analysis. The morphological and chemical similarity of the phases to those originally present in a biscuit fired bone china body was clearly demonstrated. This similarity supports the choice of the experimental material for the interface studies undertaken with these phases in the second part of the study.