An artificial neural network-based prediction model for utilization of coal ash in production of fired clay bricks: A review

This study analyzed the last 20 years` data available on power plant coal ashes used in clay brick production. The statistical analysis has been carried out for a total of 302 cases based on the relevant parameters reported in the literature. The chemical composition of the clays and coal ashes, percentage incorporation and maximum particle size of ash, size of fired samples, peak firing temperature, and the corresponding soaking time were selected as inputs for modeling. The product characteristics i.e. open porosity, water absorption, and compressive strength was taken as output parameters. An artificial neural network model has been developed and showed a satisfactory fit to experimental data and predicted the observed output variables with the overall coefficient of determination (r2) of 0.972 during the training period. Besides, the reduced chi-square, mean bias error, root mean square error, and mean percentage error were utilized to check the correctness of the obtained model, which proved the network generalization capability. The sensitivity analysis of the model suggested that the quantity of Na2O coming from brick clays, the percentages of SiO2 and K2O coming from ashes, and MgO coming from clays were the most influential parameters in descending order for the ash-clay composite bricks` quality, mostly owing to the influence of fluxes during firing.

A possible connection between phosphate tungsten bronzes properties and Briggs-Rauscher oscillatory reaction response

The calcium phosphate tungsten bronze (Ca-PWB) has been synthesized and characterized (TGA, DSC, XRPD, FTIR, SEM). The influence of solid insoluble materials Ca- PWB, as well as lithium doped (Li-PWB) and cation free phosphate tungsten (PWB) bronzes on the oscillatory Briggs-Rauscher (BR) reaction dynamics, is compared. The results show that doping with Li and Ca reduces sensitivity of the BR reaction towards bronzes addition. These findings suggest the usage of the BR reaction as an innovative method for testing of different properties of bronze material. The behavior of PWB in the BR reaction is significantly changed with divalent cation (Ca2+) doping. The reasons for the different bronzes behavior were found in their calculated unit cell volumes. Namely, the compressed Ca-PWB unit cell volume indicates the difficult availability of the active site for heterogeneous catalysis. Hence, the linear correlation (slope) of the BR oscillogram?s length (?osc) vs. mass of bronze in BR reaction might be considered as a new parameter for the evaluation of the bronzes catalytic activity.

Preparation, microstructure studies and mechanical properties of glazes ceramic sanitary ware based on kaolin

In this paper, the use of local kaolin coming from Djebel Debbagh (denoted DD1) in the composition of ceramic glazes for sanitary ware was examined. Because of its natural abundance, low price and good characteristics, this kaolin represents an interesting economic alternative to other mineral clays. The chemical composition showed that this kaolin contains 38.49 wt.% Al2O3 and 44.85 wt.% SiO2. Two glazes based on kaolin DD1 denoted as GaDD1 and GbDD1 were prepared with conventional ceramic processing techniques at temperature 1250 oC. As a reference, another glaze (Gref) based on kaolin Remblend was also prepared in the same conditions. The samples were characterized with X-ray diffraction and Scanning Electron Microscope. The results revealed that zircon and quartz are the crystalline phases present in these glazes. In the sample GaDD1, it was found that the degree of whiteness is very high and reaches 93.30 %. However, the water absorption coefficient is low which is about 0.19 ? 0.04 %. In addition, the flexural strength and the Vickers microhardness are respectively, about 56.07 ? 5.61 MPa and 7952.80 ? 101.76 MPa. These properties are compatible with those of the glaze reference Gref and commercial sanitary ware glazes, indicating the potential use of kaolin DD1 in the production of glazed ceramic for sanitary ware applications.

Structural transformations of a gas-atomized Al62.5Cu25Fe12.5 alloy during detonation spraying, spark plasma sintering and hot pressing

In this work, we traced structural transformations of an Al62.5Cu25Fe12.5 alloy, in which a quasicrystalline icosahedral phase (i-phase) can be formed, upon spraying onto a substrate and consolidation from the powder into the bulk state. The Al62.5Cu25Fe12.5 powder was obtained by gas atomization and consisted of i-phase and ?-phase AlCu(Fe). The powder was detonation sprayed (DS) and consolidated by spark plasma sintering (SPS)/hot pressing (HP). During DS, the particles experienced partial or complete melting and rapid solidification, which resulted in the formation of coatings of a complex structure. The composite regions containing i-phase were inherited from the powder alloy. The fraction of the material that experienced melting solidified as ?-phase AlFe(Cu) in the coating. It was suggested that the difficulty of obtaining i-phase upon post-spray annealing is related to aluminum depletion of the alloy during DS. During SPS and HP, the elemental composition of the alloy was preserved, while the exposure to an elevated temperature led to phase homogenization. SPS and HP conducted at 700?C resulted in full densification and the formation of a single-phase quasicrystalline alloy. The sintered single-phase alloy showed a higher microhardness in comparison with the DS coatings.

Low-temperature sintering of high-siliceous clay under conditions of oxygen deficiency

In the work, the processes of phase reconstruction and properties of ceramics obtained from high-siliceous clay-sand, clay-cullet, and clay-sand-cullet mixtures are considered. It is possible to perform plastic molding of blanks from the given mixtures due to the presence of montmorillonite in clay and sand and sintering at 800 oC for 8 h under conditions of oxygen deficiency. Depending on the composition of the initial mixtures, specimens ranging in color from gray to black can be obtained. It has been established by the XRD, IR spectroscopy, and electron microscopy methods that the synthesized material is glass ceramics consisting of quartz, feldspars, and a glass phase. Depending on the content of the initial components in the mixtures, it is possible to obtain glass ceramics with high strength properties or coarse-pored glass ceramics whose properties are similar to those of foamed ceramics.

Incandescent combustion synthesis of nanomagnetic Ni/NiO composites

This study is the first attempt to large-scale energy-efficient production of nanomagnetic Ni/NiO composites by using the autocombustion based on leaves or extract of corchorus olitorius. The as synthesized product can be characterized by using XRD, SEM, TEM and EDX techniques. The results confirm that the as synthesized materials consisted entirely of well crystalline Ni and NiO phases. The crystallinity of both Ni and NiO enhanced by increasing amount of the corchorus olitorius. However, the corchorus olitorius - treatment resulted in an increase in the crystallite size and lattice constant. The SEM analysis confirms formation of fragile, fluffy and spongy networks. The average of grain size for the as prepared particles was found to be 45 nm in agreement with the trend of the crystallite size calculated by using XRD technique. Furthermore, changing of nature and content of the corchorus olitorius brought about progressive modifications in the magnetic properties, namely, Ms, Mr, Mr/Ms, Hc and Ka, of the fabricated Ni/NiO nanocomposite according to the structural, morphological as well as microstructural variation. The saturation magnetization (Ms) of the sample with corchorus olitorius leaves was found to be 0.2383 emu/g while the Ms with corchorus olitorius extract was found to 6.977 emu/g. This was discussed in the light of finite size, surface and interface effects. Thus, we unveil a new approach for incandescent combustion synthesis via an innate approach for corchorus olitorius leaves in the directly fabrication for different nanocomposites.

Thermally induced phase transformation of Mn-LTA and Mn-FAU zeolite to anorthite phases

Data on thermally induced transformations of Mn exchanged zeolites LTA and FAU topology are presented in this paper. Thermally induced phase transformation of Mn-exchange zeolites are followed in the range from 700 to 1300?C. Both frameworks collapse into amorphous intermediate products after heating between 600 and 650?C. Prolonged heating of the intermediate product above 1100?C results directly in formation of a disorder Mn-anorthiteLTA and Mn-anorthiteFAU. The parameter of unit cell of Mn-anorthiteLTA and Mn-anorthiteFAU, in temperature range between 700 and 1300?C, was observed in space group C-1. The phase conversions in the temperature range investigated were followed by thermal, X-ray powder diffraction and FT-IR analyses

Effect of TiO2 in fine zircon sintering and properties

The effect of the TiO2 addition in the ceramic processing of dense zircon materials from zircon fine powders was established. The addition of TiO2 (5-10 wt%) permitted to obtain dense ceramics at lower temperatures (100-150 oC below), with comparable mechanical behavior. The thermochemical processes were described after a multi-technique experimental approach, which included a sintering analysis, powder X-Ray diffraction analysis (XRD), scanning electronic microscopy (SEM) and Vickers hardness of the polished dense obtained ceramics. After 1400 oC heating programs, the added TiO2 acts as a sintering aid with no important chemical reactions, and presented improved mechanical behavior in comparison with pure zircon ceramics. On the other side, in samples fired at 1500 oC, TiO2 partially (?50 %) reacts with zircon, forming ZrTiO4, while the formed SiO2 goes to the grain boundaries. Samples with 5 wt% TiO2 present better mechanical behavior than the ones with 10 wt%. The performed mechanical characterization indicates the merits of the material processed by this inexpensive processing route. Developed density, hardness (?10 GPa) and fracture toughness (?2 MPa.m-1/2) are comparable with the best figures reported.

Tribological and aging behavior of hybrid Al 7075 composite reinforced with B4C, SiC, and TiB2

In this study, B4C+SiC/B4C +TiB2/SiC+TiB2 hybrid reinforcements were added to Al 7075 matrix via the powder metallurgy method. The powders were subjected to mechanical grinding for 240 min, as shown in the graphical abstract. The hybrid composite powder structure produced by the mechanical grinding was then placed in a vertical casting chamber and molten Al 7075 (main matrix) was added to obtain the samples. Samples were dissolved for 1 h at 480 ?C, and then aged at 120 ?C in 4-h increments (32 h in total). After the aging process, the wear behavior of the samples was investigated. In the study, FESEM images were examined for microstructural analysis, and hardness plots of the aged samples were created depending on the time after the solutioning treatment. The friction coefficient, volume loss, and worn surface images were investigated to determine the wear behavior of the hybrid structures. Results showed that the increased reinforcement rate and the reinforcement size and type directly affected the hardness and wear behavior. In the experiments, the highest hardness and wear resistance behavior were obtained in the hybrid sample of 3% B4C + 3% SiC after 12 h of aging.

Structural and optical properties of HDPE implanted with medium fluences silver ions

The implantation of high-density polyethylene (HDPE) has been conducted using Ag+ ions with energy of 60 keV, achieved fluences 1.5 and 10?1015 ions/cm2. Transmission electron microscopy (STEM) and field emission gun - scanning electron microscopy (FEG-SEM) showed the existence of nanoparticle clusters. X ray photoelectron spectroscopy (XPS) revealed the presence of silver in the sample surface region. The surface topography was studied by atomic force microscopy (AFM), while the surface composition uniformity was analyzed using phase imaging AFM. Optical characterization obtained by spectroscopic ellipsometry (SE) showed changes in refractive index, extinction coefficient and the optical band gap with the fluence of implanted ions.