Tricalcium silicate phase is one of the main components of modern Portland cements. One of the major industrial challenges in the field of cement production is mapping the influence of individual ...clinker minerals and their polymorphs on the properties of industrially produced clinkers. The primary goal of this work is to improve the fundamental knowledge of understanding the process of alite formation and development from a crystallographic point of view. This study focuses on the observation of the crystallization process of triclinic alite during the firing process, which to date has not been thoroughly described. The effects of a wide range of temperatures and sintering periods on crystallinity were assessed on samples fired in platinum crucibles in a laboratory furnace. X-ray analysis—together with calculation of crystallinity using Scherrer’s equation—was used for observing the crystallite size changes of T1 alite polymorph. According to the acquired results, among the most technologically and economically advantageous regimes of production of a high-quality triclinic alite is the temperature of 1450 °C and sintering time of two hours. The most significant changes in the crystallite size occurred within the first hour of sintering for the whole investigated temperature range.
This study focuses on the investigation of uniquely sequenced Cu-Al clad composite wires, which are considered as perspective materials for applications within a wide range of industrial and ...commercial branches. The wires were produced by rotary swaging under variable temperature (at 20 °C and 250 °C). The required diameter of the final wire was 5 mm, however, detailed analyses were performed on 10 mm, 7.5 mm, 6 mm and 5 mm samples. The swaged composite wires were studied from the viewpoints of deformation behaviour, structure and mutual interfaces, and electric and mechanical properties via scanning and transmission electron microscopy and neutron diffraction, testing of electrical resistivity, and mechanical testing with implemented acoustic emission detection. The results showed non-negligible effects of both the variables/influencing factors (swaging degree and temperature) on the investigated parameters. The development of intermetallics was observed at the interfaces of samples swaged with high swaging degrees, but only at 250 °C. These intermetallics provoked signal activity during acoustic emission detection and deteriorated the electric conductivity. On the other hand, substantial work hardening occurring during swaging at 20 °C also decreased the conductivity. By these reasons, the electric properties were the poorest for work hardened samples with occurring intermetallics. Both the final 5 mm composites exhibited satisfactory bonding of both the components and recrystallized structures with ultra-fine grains ensuring the ultimate tensile strength higher than 200 MPa.
This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches ...of Portland cement featuring 6-7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m
/kg, with the step of 50 m
/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m
/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged.
Tristal steel is low-carbon construction-type steel widely used in the automotive industry, e.g., for braking components. Given the contemporary demands on the high-volume production of such ...components, these are typically fabricated using automatic sequential machines, which can produce components at strain rates up to 103 s−1. For this reason, characterising the behaviour of the used material at high strain rates is of the utmost importance for successful industrial production. This study focuses on the characterisation of the behaviour of low-carbon steel via developing its material model using the Johnson-Cook constitutive equation. At first, the Taylor anvil test is performed. Subsequently, the acquired data together with the results of observations of structures and properties of the tested specimens are used to fill the necessary parameters into the equation. Finally, the developed equation is used to numerically simulate the Taylor anvil test and the predicted data is correlated with the experimentally acquired one. The results showed a satisfactory correlation of the experimental and predicted data; the deformed specimen region featured increased occurrence of dislocations, as well as higher hardness (its original value of 88 HV increased to more than 200 HV after testing), which corresponded to the predicted distributions of effective imposed strain and compressive stress.
The patatin-like phospholipase domain containing 3 (PNPLA3) gene (viz. its I148M variant) is one of the key players in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). We have identified ...a novel insertion/deletion variant of 1114 bp, localized in the second intron of the PNPLA3 gene, which corresponds to the 3' terminal sequence of the long-interspersed element (LINE-1). DNA analysis of 122 NAFLD patients and 167 control subjects as well as RNA analysis of 19 liver biopsies revealed that the novel variant is very common (frequency = 0.41), fully linked to the clinically important I148M variant, and clinically silent. Although the LINE-1 insertion does not seem to have any biological effect, it can impede genotyping of the I148M variant. If insertion prevents the attachment of the diagnostic primer, then the non-insertion allele will be selectively amplified; and thus the frequency of the 148M "risk" allele will be significantly overestimated due to the complete linkage of the LINE-1 insertion and the 148I allele of the PNPLA3 gene. Therefore, our findings underline the importance of careful design and consistent documentation of the methodology, including primer sequences. Critical revisions of the results of some studies that have already been reported may therefore be needed.
This article deals with the development of an alternative method for determining the grindability index of fine-grained materials. This method is inspired by the commercially used VTI method (also ...known as RTI after the Russian Thermal Energy Institute), which was widely used in Central and Eastern Europe in coal grinding. The disadvantage of the VTI method is that it uses a specific grinding device that otherwise has no other use and nowadays is no longer commonly available. Through the new method, high-energy grinding was performed using a commercially available planetary mill on silicate materials such as limestone, feldspar, corundum, and quartz. The effectiveness of the method was verified on clinker as a representative of widely used materials. The deviation between the grindability index calculated by the origin VTI method and the new developed method was on average approximately 8%; in the case of clinker grinding, it was only 3%. The results showed that the VTI method could be replaced by a new method that uses a modern available planetary mill and laser granulometry to determine the grindability index. The result is a new classification of materials according to their grindability indexes, which is based on the original VTI method.
•Silica by-product (the production of AlF3) was used for zeolite synthesis.•In silica by-product dominated amorphous SiO2 and crystalline AlF3·3.5H2O compound.•By using sonication (5–20 min) and ...hydrothermal treatment Na-P and Na-X zeolites formed.•The sonication efected to the formation of the diamond shape of Na–P zeolite.•In the synthesis products the total amount of zeolites was in the range of 89–93%.
The fine powdered silica by-product of processing of aluminum fluoride (fertilizer plant, Lithuania) was used for zeolite synthesis as silica and aluminum source. The effect of sonication time and the time of hydrothermal synthesis on crystallinity of the synthesized zeolite were studied. This allowed the transformation of the by-product to the mixture of Na–P zeolite and Na–X zeolite. It was determined that ultrasonic-assisted hydrothermal action effected the “diamond” shape formation of Na–P zeolite with clear crystal edges. Na–P zeolite had the morphology of pseudo-spherical forms constituted by small plates when hydrothermal treatment (without sonication) was use for the preparation of zeolites. Moreover, it was determined that ultrasonic-assisted hydrothermal method effected a reduction in the crystal size compared with the zeolites which were synthesized only by using hydrothermal synthesis. The total amount of zeolites as high as 88–93% was achieved after 24 h of hydrothermal treatment followed or unfollowed by sonication. By using longer duration (20 min) of ultrasound pretreatment it is possible to reduce the duration of hydrothermal synthesis: from 24 h to 12 h of hydrothermal treatment. In this case, similar results of total amount of zeolites were detected. In the present work, low-cost raw materials, such as silica by-product have been investigated for the production of zeolites.
Tricalcium aluminate is an important phase of Portland clinker. In this paper, three polymorphs of C
A were prepared by means of the solid-state synthesis method using intensive milling of the raw ...material mixture which was doped with various amounts of Na
O and sintered at a temperature of 1300 °C for 2 h. The final products were evaluated through X-ray diffraction using Rietveld analysis. The effect of the Na dopant content on the change in the crystalline structure of tricalcium aluminate was studied. It was proven that the given preparation procedure, which differed from other studies, was close to the real conditions of the formation of Portland clinker, and it was possible to prepare a mixture of different polymorphs of calcium aluminate. Fundamental changes in the crystal structure occurred in the range of 3-4% Na, when the cubic structure changes to orthorhombic. At a dosage of Na dopant above 4%, the orthorhombic structure changes to a monoclinic structure. There are no clearly defined boundaries for the existence of individual C
A phases; these phases arise at the same time and overlap each other in the areas of their formation at different Na doses.
Titanium silicides are promising candidates for use as a reinforcement in advanced light-weight composites due to their excellent mechanical properties and oxidation resistance at high temperatures, ...sufficient wear resistance, and high chemical stability in various corrosion environments. Direct in-situ synthesis of such composites from titanium-silicon (Ti-Si) powder feedstock by spark plasma sintering (SPS) was used in this study with a particular attention on the effect of the powder processing parameters (blending, co-milling, milling + blending) on the microstructure formation and mechanical properties of the sintered composites. As opposed to the previous silicide-reinforced Ti studies, this was done for high silicone content (20 wt%). It was found that, despite the powders initial identical composition, the microstructure and phase content of the compacts varied significantly with the used powder fabrication route. Taking advantage of this, composites ranging from relatively soft metal-matrix (52 vol% metallic Ti; using non-milled Ti and coarse or fine-milled Si) to hard ceramic-matrix (11 vol% metallic Ti, using fine-dispersed joint-milled mixture of Ti and Si) were obtained. Due to in-situ formation of various TiSi2, TiSi, Ti5Si4 and Ti5Si3 silicide reinforcement phases contents with high hardness and stiffness, all the sintered composites showed superior hardness and wear resistance (an increase as much as 44×) in comparison to pure Ti. Importantly, hardness and elastic modulus of intermediate compounds TiSi2, TiSi, Ti5Si4 and Ti5Si3 were measured using instrumented indentation technique for the first time and are presented in the paper.
•In-situ synthesis of Ti composites alloyed with high Si content achieved via SPS.•Feedstock powder blend processed via three PM processing routes.•SPS compacts phase composition significantly affected by the selected route.•Superior sliding wear resistance was recorded for the silicide-reinforced matrices.•Nanoindentation properties of Ti5Si3, Ti5Si4, TiSi and TiSi2 phases are disclosed.
PDF
