Optical Dilatometer Research Articles

Influence of the pressure of compacted glass powders on the final structure of sintered glass-ceramics

In reported investigation we studied sintered glass-ceramics from a model diopside glass with moderate crystallization ability by in-situ optical dilatometeric experiments. The initial glass was ground and sieved below 75 μm. Then thus prepared powders were pressed with different pressures between 50 and 250 MPa. In this way were obtained samples out of pressed powders with different initial porosities determined with gas pycnometry. Then the samples were heat treated in a contactless horizontal optical dilatometer and their porosities were measured one more time. Both pressed green samples and synthesized glass-ceramics were analyzed further with X-Ray micro tomography.We observed that the densification of all samples completes in the same moment which corresponds to the formation of a critical percentage crystal phase. Notwithstanding the continuation of the crystallization process, we obtain materials with different percentage of residual porosity. Then no volume variation of the system is observed. This approach is well demonstrated by the first derivative of the shrinkage curves with time.After the end of the shrinkage of the system, the crystallization leads to the formation of crystallization induced porosity (called by us CIPs) observed here.

Optimization of SOFC Anode Microstructure for Performance and Highly Scalable Cells through Graded Porosity

The performance and durability of anode supported solid oxide fuel cells is heavily dependent on the porosity of their anode layer. An optimal amount of porosity is needed to achieve high performance without compromising the flatness, and by extension, the hermetic sealing of the cell. This presents challenges for commercialization, as anode porosity heavily influences the densification of the cells during sintering. In this work, the effect of pore former loading was evaluated on both cell performance and curvature. It was also found that anodes with an intermediate amount of pore former had the best performance but also the most curvature. The mechanism behind this was evaluated with an optical dilatometer. As expected, when cells were sintered with thicker anode support layers, they resulted in significantly flatter cells. Improvements to performance but not flatness were achieved with the use of graded porosity in the anode, with high porosity at the fuel side that decreased closer to the electrolyte. This effect was more pronounced at lower temperatures and fuel ratios, further demonstrating that this is a more efficient microstructure for the anode than a typical anode with uniform porosity. The use of graded porosity was then evaluated as a means of improving the performance of thicker anodes, to take advantage of their greater flatness and mechanical strength. Unfortunately, thicker anodes exhibited a significant drop in performance. It was found that the greater distance for gas diffusion in thicker anodes means that a different microstructure is needed for efficient gas flow and charge transfer. In the case of thicker anodes, it was found that having two anode regions, one thinner region with moderate porosity adjacent to the anode functional layer and one with high porosity making up the bulk of the anode resulted in the best performance. This allows sufficient fuel flow in a thicker anode, without significantly reducing the activity of the anode. In this way, this anode microstructure behaves similarly to an anode functional layer, which is well known to improve fuel cell performance. While graded anode microstructures have been reported before, there have been few, if any, studies that evaluated both their performance and flatness simultaneously. Optimization of anode porosity in anode supported cells is essential to improving both their performance and reliability, which are necessary for widespread adoption of SOFCs.

Investigation of the use of nano-titanium dioxide particles synthesized by reflux method as a whitener agent in standard porcelain tiles

The effects of adding zircon and synthesized TiO2 nanoparticles (NPs) to standard porcelain tiles on mechanical and optical properties were studied. The obtained TiO2 nanoparticles had an average particle size of 7.47nm. The optical properties of TiO2 NPs were characterized by using UV–visible spectrophotometer. The synthesized TiO2 NPs and commercial zircon were added to standard porcelain tile composition at a rate of 1%, 2% and 4% by weight. Phase analyzes of the samples were made with XRD, and microstructure analyzes were made with SEM/EDS. Optical dilatometer test was used for sintering studies and densification behaviour was observed with water absorption test. The optical behaviour of the samples was analyzed using spectrophotometric measurements (CIELab method). As a result of this test, it was observed that nano-sized titanium oxide can be used as a whitening agent in porcelain tiles. In addition, the additives made to porcelain tiles also contributed to the increase in mechanical properties.

The Effect of Bio-Coal Agglomeration and High-Fluidity Coking Coal on Bio-Coke Quality

Metallurgical coke with high strength and low reactivity is used in the ironmaking blast furnace. Replacement of some coking coal with bio-coal was shown to result in lower strength and higher reactivity of produced coke due to introduction of reactive bio-coal carbon and ash components catalyzing the Boudouard reaction, but also due to lowering of the coking coal blend fluidity, which influences coke strength and reactivity negatively. The current study aims to investigate the possibility to counteract negative impact from bio-coal addition on fluidity and coke reactivity by using high-fluidity coking coal and by agglomeration of bio-coal before addition. Original bio-coal and micro-agglomerate of bio-coal was added at 10%, 15% and 20% to the coking coal blend. The influence of bio-coals on the coke reactivity was measured by using CO2 in a thermogravimetric analyzer. Selected cokes and bio-cokes were produced in technical scale, and their reactivity and strength were measured in standard tests. The effect on dilatation of adding bio-coal or crushed agglomerates of bio-coal to the coking coal blends was measured in an optical dilatometer. The results show that by using a coking coal blend containing high-fluidity coal with agglomerated bio-coal, the max. contraction is increased, whereas the opposite occurs by using original bio-coal. The results show overlapping between contraction occurring before dilatation and during dilation, which affects max. dilatation. The bio-coke containing high-fluidity coal with agglomerated bio-coal has lower reactivity in comparison to bio-cokes with original bio-coal or bio-coke with agglomerated bio-coal produced from a coking coal blend without high-fluidity coal. The reactivity of coke produced in technical scale, as measured in CRI/CSR tests, shows a similar trend regarding reactivity, as measured by thermogravimetric analysis, on coke produced in laboratory scale.

Influence of Modified Bio-Coals on Carbonization and Bio-Coke Reactivity

Substitution of coal in coking coal blend with bio-coal is a potential way to reduce fossil CO2 emissions from iron and steelmaking. The current study aims to explore possible means to counteract negative influence from bio-coal in cokemaking. Washing and kaolin coating of bio-coals were conducted to remove or bind part of the compounds in the bio-coal ash that catalyzes the gasification of coke with CO2. To further explore how the increase in coke reactivity is related to more reactive carbon in bio-coal or catalytic oxides in bio-coal ash, ash was produced from a corresponding amount of bio-coal and added to the coking coal blend for carbonization. The reaction behavior of coals and bio-coals under carbonization conditions was studied in a thermogravimetric analyzer equipped with a mass spectrometer during carbonization. The impact of the bio-coal addition on the fluidity of the coking coal blend was studied in optical dilatometer tests for coking coal blends with and without the addition of bio-coal or bio-coal ash. The result shows that the washing of bio-coal will result in lower or even negative dilatation. The washing of bio-coals containing a higher amount of catalytic components will reduce the negative effect on bio-coke reactivity, especially with acetic acid washing when the start of gasification temperature is less lowered. The addition of bio-coal coated with 5% kaolin do not significantly lower the dilatation-relative reference coking coal blend. The reactivity of bio-cokes containing bio-coal coated with kaolin-containing potassium oxide was higher in comparison to bio-coke containing the original bio-coal. The addition of ash from 5% of torrefied bio-coals has a moderate effect on lowering the start of gasification temperature, which indicates that the reactive carbon originating from bio-coal has a larger impact.

The roles of microlites and phenocrysts during degassing of silicic magma

Silicic magmas span a wide range of eruptive styles between explosive and effusive, and transitions between these styles are commonplace. Yet the triggers of switches in eruptive style remain poorly understood. Eruptions are mostly driven by degassing of magmatic water and their eruption style - effusive or explosive - is likely governed by the efficiency of outgassing as well as magma ascent rate. Microlites and phenocrysts are often purported to promote heterogeneous bubble nucleation and outgassing, both key variables in the degassing dynamics that become crucial in controlling the eruptive style. Here, in order to shed light on the role of nature, size and abundance of crystals on degassing of silicic magma, we experimentally investigate (heating-induced) vesiculation in a multiphase (microlite- and phenocryst-bearing), low-water content, and bubble-free, natural rhyolite. The experiments were conducted at magmatic temperature (∼900-1100°C) and atmospheric pressure in an optical dilatometer. Our results indicate that microlites exert a large influence on bubble nucleation while the effect of phenocrysts is subordinate. Amongst the microlite phases, bubbles nucleate more easily on Fe-Ti oxides than other mineral phases. Bubble coalescence and connectivity are, in contrast, enhanced by the phenocrysts, more than microlites, in low-crystallinity magma. Comparing the bubble textures of the post-experimental samples with those produced in a phenocryst-free and microlite-poor silicic magma, we observe that the phenocryst- and microlite-bearing magma exhibits significantly more bubble coalescence and connectivity, as well as higher bubble number densities. These findings help to constrain the roles that pre- and syn-eruptive crystalline phases may play in degassing processes during ascent of silicic magma.

Influence of Bio-Coal Properties on Carbonization and Bio-Coke Reactivity

Coke corresponds to 2/3–3/4 of the reducing agents in BF, and by the partial replacement of coking coals with 5–10% of bio-coal, the fossil CO2 emissions from the BF can be lowered by ~4–8%. Coking coal blends with 5% and 10% additions of bio-coals (pre-treated biomass) of different origins and pre-treatment degrees were carbonized at laboratory scale and with a 5% bio-coal addition at technical scale, aiming to understand the impact on the bio-coal properties (ash amount and composition, volatile matter content) and the addition of bio-coke reactivity. A thermogravimetric analyzer (TGA) connected to a quadrupole mass spectroscope monitored the residual mass and off-gases during carbonization. To explore the effect of bio-coal addition on plasticity, optical dilatometer tests were conducted for coking coal blends with 5% and 10% bio-coal addition. The plasticity was lowered with increasing bio-coal addition, but pyrolyzed biomass had a less negative effect on the plasticity compared to torrefied biomasses with a high content of oxygen. The temperature for starting the gasification of coke was in general lowered to a greater extent for bio-cokes produced from coking coal blends containing bio-coals with higher contents of catalyzing oxides. There was no significant difference in the properties of laboratory and technical scale produced coke, in terms of reactivity as measured by TGA. Bio-coke produced with 5% of high temperature torrefied pelletized biomass showed a similar coke strength as reference coke after reaction.

The effects of cement raw mix waste dust on thermal properties of ceramic wall tile bodies

The recycling of industrial wastes has in recent years become a priority issue. The relevant work on reducing the adverse effects of industrial wastes is becoming more important. Farina (raw mix) is a crude mixture obtained by grinding the raw materials used in cement production. The oxides at a high rate ensure that the cement raw mix waste dust is a good source of raw material in ceramic wall tile body production. This study used 2%, 3%, 5% and 10% cement raw mix waste dust instead of calcite, which is used in a standard wall tile recipe. Another industrial waste, marble dust, was also used as a source of CaCO3. The physical and mechanical properties of prepared samples such as firing shrinkage, dry and fired strength, and water absorption were examined. And firing behavior using a non-contact optical dilatometer was also studied. The study showed that the addition of cement waste raw mix dust improves physical and mechanical properties. Dry strength and bending strength increased as the amount of cement waste raw mix dust increase. Bulk density also increased with the addition of cement waste raw mix dust. Especially, 50% increase in dry strength was achieved with the addition of cement waste raw mix dust instead of calcite. The sintering rate (dy/dt) was negatively affected, and sintering slowed down when the higher amount of the addition cement waste raw mix dust. The study showed that cement waste raw mix waste dust and marble dust can be used as alternative raw materials for ceramic wall tiles up to 5 wt % instead of CaCO3.

Design of an instrumented microwave multimode cavity for sintering of nuclear ceramics

This paper describes the development of an innovative instrumented and automated 2.45GHz multimode microwave cavity for sintering of uranium oxide based nuclear fuels (UO2, (U,Pu)O2, (U,Am)O2 …). The cavity and the sintering cell were designed using Finite Element simulation and the expertise acquired over years on microwave heating. This original setup allows for hybrid and homogeneous heating of nuclear fuels. Reliable in situ monitoring of the samples' shrinkage and temperature is performed with an optical dilatometer and infrared pyrometers calibrated with a specific protocol. A dedicated software including a Proportional-Integral-Derivative (PID) controller was developed to precisely control the sintering cycles like under conventional heating. The setup is also designed for operating in a glovebox under reducing sintering atmosphere.A stable and homogeneous heating with controlled sintering cycles is reached to successfully sinter UO2 crack free pellets to high density. This is a key point of innovation compared to previous studies in the literature on microwave sintering of nuclear ceramics. The pellets' final densities are equivalent to those obtained under conventional sintering, but with a significant decrease in the total duration of the sintering cycle.

Thermal behaviour and microstructural evolution of metakaolin and meta-halloysite-based geopolymer binders: a comparative study

Two calcined clays (halloysite and kaolinite clays at 700 °C) were used as solid precursors for geopolymer synthesis. This study compares the physicochemical properties of the both resulting geopolymer series heated at 200, 400, 600 and 800 °C. The end specimens were characterized using Optical Dilatometer, XRD, FTIR, MIP and SEM analyses. Results revealed that the flexural strengths were 18.10 and 21.74 MPa for meta-halloysite- and metakaolin-based geopolymers, respectively. After subjected to high temperatures, the flexural strength drastically decreased from 18.10 ± 1.06 to 6.7 ± 0.23 MPa and 21.74 ± 1.20 to 4.63 ± 0.24 MPa, respectively. The maximum shrinkage recorded on metakaolin and meta-halloysite-based geopolymers was 14 and 16% around 950 °C, respectively. The thermal conductivities decreased with increase in heating temperature from 0.78 to 0.19 Wm−1 K−1 and 0.96 to 0.26 Wm−1 K−1, respectively. This reduction is linked to the additional voids and microcracks that occurred within the geopolymer network. The cumulative intrusion in both geopolymers increased with increase in heating temperature up to 600 °C, leading to the degradation of geopolymer network that affected the mechanical strength evolution. Both synthesized geopolymer series are potential candidates for insulation materials or refractory applications.

Effect of fluxing raw materials on moisture expansion of monoporosa wall tile bodies

In the production of wall tiles, trends are moving toward larger-format wall tiles. Moisture expansion of larger-format wall tiles is one of the most important technological parameter that determine the quality of their service life. Clay, kaolin, quartz, carbonate and less fluxing materials are generally used in monoporosa tile recipes. In this study, alkali containing raw materials such as perlite, rhyolitic tuff, granite and nepheline syenite, were used instead of quartz and kaolin in the recipes. The investigated bodies are fired under industrial fast firing cycle at 1150 °C—50 min. Firing shrinkage, water absorption and color values (L*, a*, b*) of alkaline raw materials and bodies were measured. Thermal expansion coefficient and moisture expansion values of the bodies were determined by dilatometer and the sintering behavior of the representative formulations was evaluated using a double-beam non-contact optical dilatometer (ODHT). Phase and microstructural analyses were performed by XRD and SEM, respectively. As a result, the analytical data obtained from this study revealed that the alkaline/flux materials which have more or less similar chemical compositions, represent distinctly different physico-mechanical behavior. According to the petrographical examinations, whereas the holocrystalline textured alkaline materials such as nepheline syenite and granite decrease moisture expansion, the use of amorphous-glassy textured raw materials such as perlite and rhyolitic tuff increase moisture expansion in monoporosa tile body manufacturing. Using of the alkali raw materials as a partial replacement of quartz also enables the development of lower thermal expansion bodies.

Mixed Alkali and Mixed Alkaline-Earth Effect in Ceramic Sanitaryware Bodies Incorporated with Blast Furnace Slag

Raw materials and energy are among the most important costs in ceramic sanitaryware production. With the decrease in raw material sources and increasing costs of energy in recent years, researches on alternative raw materials and energy have started to gain importance. In this study, blast furnace slag and spodumene were used to reduce both energy and raw material costs. In standard vitreous china ceramic sanitaryware, a maximum of 15% blast furnace slag and 4% spodumene was used instead of sodium feldspar. In this study, the effects of CaO, MgO, and Li2O on microstructure, technological properties such as flexure strength, water absorption, porosity, bulk density; and also, thermal properties such as sintering analysis were investigated by using a non-contact optical dilatometer and thermal expansion. The dry strength and flexure strength of fired samples increased. The increase in dry strength was approximately 47%. The increase in flexure strength was approximately 67%. The reduction in the thermal expansion coefficient values was approximately 17%, which is also important in terms of stability of the final product. As a result, the use of blast furnace slag and spodumene will result in a reduction in both energy and raw material costs. The spodumene and BFS provided a reduction in sintering temperature at a rate of approximately 60 °C. The flue gas emissions may also reduce because flue gas emissions are higher as the temperature inside the furnace is higher. The spodumene and blast furnace slag addition provide a decrease in the peak of sintering temperatures so that flue gas emissions will reduce.

A novel densification model for sintering Li7La3Zr2O12-based solid electrolytes for all solid-state Li-ion batteries

Improving the safety features of traditional Li-ion batteries having a flammable liquid electrolyte is one of the current challenges that scientists have been trying to overcome. Inorganic solid ionic conductors are promising option to replace the liquid electrolytes in Li-ion batteries because of their high temperature stability. But their poor ionic conductivity is one bottleneck that prevents them in a widespread use. In order to increase the ion conduction, the electrolytes should be as dense as possible since pores have no contribution to ionic conductivity. For densification assessments during sintering of Li7La3Zr2O12, one of the popular inorganic solid ion conductors in the field of all solid-state Li-ion batteries, the Archimedes density measurement technique has been widely used. However, the Archimedes density itself is not sufficient enough to enlighten the densification behavior of Li7La3Zr2O12 since closed porosities that are very common in Li7La3Zr2O12 microstructures cannot be wetted by the immersed liquid. In this study, a densification model which combines Archimedes density with radial shrinkage, dilatometer, and microstructure for more accurate assessment of Li7La3Zr2O12 densification was offered. Optical dilatometer results showed shrinkage initiation after 980 °C. Archimedes densities were initially increased from 4.24 to 4.76 g/cm3 at the early stages of sintering and then stayed constant at 4.76 g/cm3. On the other hand, radial shrinkage showed continual increase from 7.33 to 13.20% pointing out the linking of closed porosities and grain separation.

Porselen Karo Üretimlerinde Konya Kili Kullanımı

Porcelain tiles are the most preferred products in ceramic tiles due to their low water absorption, superior mechanical and aesthetic properties. Ukrainian clays are used in the production of these products because of their low iron content and high plasticity, The Ukrainian clay is an imported raw material and its price increases every year, and so it increases the cost of the production of porcelain tiles. In this respect, the use of local raw materials will provide a significant cost advantage to ceramic companies. In the study, the use of Konya clay instead of Ukrainian clay was investigated in porcelain tile body compositions and the effects on the technical properties of the bodies were determined. For this purpose; Ukrainian clay was gradually removed and Konya clay were added to the standard porcelain tile composition of Usak Ceramic. The developed bodies were fired in Usak Ceramics industrial roller kilns at 1210 ° C for 52 minutes. All physical and optical properties of the bodies were examined. Sintering behaviors were examined by optical dilatometer and thermal expansion coefficients were measured by dilatometer. The phases developed in the body were determined by XRD analysis and microstructure investigations were made by scanning electron microscopy. According to the results, the use of Konya clay instead of Ukrainian clay in the body increases the dry strength values, water absorption and firing shrinkage values ​​of the bodies. As a result, it was determined that the use of Konya clay would be possible with some optimizations in the composition of porcelain tiles.

THE EFFECT OF COMBINATION OF BORIC ACID AND LITHIUM CARBONATE ON SINTERING AND MICROSTRUCTURE IN SINGLE FIRING WALL TILE

The aim of this study was to determine the effect of boric acid and lithium carbonate on microstructure and sintering characteristics of wall tile after firing. Amount of Li2 (CO3) (0.1-0.3-0.6- 0.9-1.2-4 wt.%) were added in wall tile corresponding to each constant amount of added of H3BO3 (0.1-0.3-0.6-0.9-1.2-2 wt.%). All samples were fired in 1135 0C 35 minutes in an industrial fast firing kiln. Dry strength, fired strength, water absorption and colorimeter values of all samples were determined after firing. Scanning electron microscope (SEM), x-ray diffraction (XRD) analysis, optical dilatometer measurements were performed in order to determine the microstructure and melting temperature for prescribed purpose (1-2-7-8-11-32-37). Standard (1) and alternative (8) receipe’s thermogravimetric and diferantial thermal analyses were performed. 37 (2% H3BO3 + 4% Li2 (CO3) recipe’s sintering starting temperature was 984 0C. In the recipe 8 (0.3% H3BO3 + 0.1% Li2(CO3) is an alternative to the standard wall tile, which can be used with higher strength values.

Whiteness improvement of porcelain tiles incorporated with anorthite and diopside phases

In recent years, porcelain tiles have been increasingly used as an alternative to natural stone and marble. Moreover, the expectation of the development of more white porcelain tile bodies is also increasing. The aim of the present study is to develop ultra-white porcelain tile compositions which have significantly higher whiteness value (L* > 90) than the standard super-white porcelain tile composition because of diopside and anorthite crystallization during sintering. For this purpose, a frit which is crystallizing to diopside was used in the new composition in the present studies. Firing shrinkage, water absorption and color values (L*, a, b) of the compositions were measured. Thermal expansion coefficient values of the bodies were determined by a dilatometer; the sintering behaviors were evaluated using a double-beam non-contact optical dilatometer (ODHT). The phase analyses of the fired bodies were achieved using XRD. Microstructural analyses were carried out with SEM. According to the results, ultra-white porcelain tile compositions which are suitable for production conditions could be developed. With an industrial perspective, the other important findings are that these compositions have lower firing shrinkage and lower thermal expansion coefficient than the standard porcelain tile formulation. This provides a wide working range in terms of pressing and production by preventing the deformation problems and reducing the risk of thermal shock.

Mineralogical and thermal characterization of a volcanic ash: Implications for turbine interaction

Volcanic ash (grain size < 2 mm) is a ubiquitous product of explosive volcanic activity. Substantial input of volcanic ash into the atmosphere can lead to repetitive chronic global climate effects whose atmospheric impacts may have durations of up to years. In addition, several recent incidents document the acute hazard potential of volcanic ash interacting with infrastructure supporting technologies. One prominent example is the interaction of volcanic ash with operational jet engine turbines in commercial and/or military aviation.The physico-chemical and phase state of ash influences substantially the thermal behavior of volcanic ash and our ability to predict that behavior and therefore depends on reliable characterization of this state. Here, we have investigated the chemical composition and mineralogy (phase state) of fresh volcanic ash from Tungurahua volcano, Ecuador, as a function of grain size (below 180 μm) in order to evaluate differences between ground-sampled ash and airborne ash, interacting with jet engines. For the sieved grain size fractions (down to <20 μm) no significant grain size dependence of ash state is observable. At the <10 μm (PM10) fraction, the influence of the separation and handling procedures requires special attention. A single-stage separation method, using a <20 μm pre-sieved ash as source material, shows no grain size dependence of the phase state whereas the use of the unsieved original ash as source material results in an enrichment of plagioclase and a depletion of glass. In contrast, a multi stage gravitational separation procedure, using the unsieved original ash as source material, leads to an enrichment in the glassy phase and a depletion in all crystalline mineral phases. We thus infer that the phase state of the PM10 fraction strongly depends on the choice of starting material and the separation procedure.Using an optical dilatometer image analysis, we have characterized the thermal behavior of the volcanic ash upon heating, which we parameterize in terms of four characteristic temperatures. Using these data the determination of the flow temperature is refined to improve measurement accuracy for fine-grained (<63 μm) volcanic ash.

Thermal induced deflection of a porcelain–zirconia bilayer: Influence of cooling rate

ObjectiveTo determine the thermal expansion of a porcelain (VM9) and tetragonal zirconia (Y-TZP) as well as the deflection upon re-heating and cooling of a bilayer fabricated from these two materials after slow and rapid cooling during initial fabrication. MethodsThe coefficient of thermal expansion (CTE) of bulk porcelain and Y-TZP as well as bilayer beam deflection was measured with a novel non-contact optical dilatometer. The influence of cooling rate during initial fabrication of the porcelain–zirconia bilayer and the bulk porcelain during subsequent heating and cooling is investigated. Specimens were heated to 900°C in the dilatometer, well in excess of the glass transition temperature (Tg) and softening temperature (Ts) of the porcelain. ResultsThe thermal expansion of the porcelain above Tg exhibits a threefold increase in CTE over that observed below Tg. Observations of the bilayer deflection reflect the difference in the CTE of the component materials and enable Tg and Ts temperatures for the porcelain to be estimated. Initial cooling rate of the porcelain and porcelain-YTZP bilayer was found to have a profound influence on the subsequent response to slow reheating and cooling as well as the resultant residual deflection. SignificanceThe estimation of the residual stress and potential for chipping of porcelain–zirconia dental restorative systems should not be based solely on thermal expansion data measured below Tg.

Addition of cement kiln dust in ceramic wall tile bodies

The volume of wastes generated from heavy industries, such as cement and steel industries, is increasing, and the cost of landfill disposal grows daily. Economical and eco-friendly areas of recycle are being developed to stop the growth of these waste products. Cement kiln dust (CKD) is a waste product in the cement industry. It contains very fine grains like cement in addition to finer particles of lime, silica, alumina and iron. These particles contain high concentrations of sulphates and alkalis. The aim was to study the effects of using CKD as an alternative source of CaO in ceramic wall tile production. Ceramic tiles compositions in different ratios were prepared with CKD (15 mass% max) rather than calcite. All shaped samples were sintered at 1150 °C. Optical dilatometer was used to evaluate sintering behaviour. Physical properties, such as linear firing shrinkage, bulk density, flexural strength and water absorption, were also measured. The bodies containing CKD showed a decrease in moisture expansion and were whiter than the body of a standard composition. This study showed that CKD is an effective CaO source in ceramic tile production.

The effect of particle size of body components on the processing parameters of semi transparent porcelain

The effect of the particle size of quartz and K- feldspar on the sintering behaviour and technical properties of semi transparent porcelain were investigated. This study was implemented by “the Factorial Experimental Design Method” to determine the effect of factors on semi vitreous porcelain production. The sintering behaviour of the samples were examined by using an optical dilatometer. The phases and their respective amounts in the microstructure were determined by way of Rietvelt X- ray diffraction (XRD) technique. Furthermore, the values such as shrinkage, water absorption, bulk density, porosity, thermal expansion, light transmission measurements were taken on the samples and the microstructures were studied by SEM. It was observed that as the particle size of quartz and K- feldspar decreased; the viscosity of the liquid phase fell down, the relative amount of secondary mullite crystals increased and the large pores were removed among the particles and the densification rate increased. Data were analysed by Minitab 13.20 software, and assessed in relation to the amount of glassy phase and its viscosity. The effect of K- feldspar particle size on the densification of porcelain is less than the change of heat treatment and quartz particle size.