scholarly journals The Effect of Chelate Compounds on the Hydration Process of MgO–Al2O3 Phase System under Hydrothermal Conditions

2021 ◽  
Vol 11 (6) ◽  
pp. 2834
Author(s):  
Ryszard Prorok ◽  
Jakub Ramult ◽  
Wieslawa Nocun-Wczelik ◽  
Dominika Madej
Keyword(s):  
Dynamic Change ◽  
Xrd Analysis ◽  
Phase System ◽  
Strong Impact ◽  
Hydrothermal Conditions ◽  
Tartaric Acids ◽  
Refractory Castables ◽  
Ceramic Bond ◽  
Al2o3 Phase ◽  
Chelate Compounds

In refractory castables during heat treatment, there is a dynamic change from a hydraulic bond to a ceramic bond. During heating, the emission of water takes place; this changes the conditions inside the material to something similar to the hydrothermal ones. This influences the processes that occur during the heating of the castables, and in consequence, the properties of the final material. The aim of the work was to evaluate the influence of the chelate compounds like citric and tartaric acids, often used in castables as dispersing agents, on the properties of the MgO–Al2O3 phase system during hydrothermal treatment. The performed tests included an XRD analysis, a thermal analysis (TG–DSC–EGA), infrared spectroscopy (FTIR), and an SEM–EDS analysis. Based on the obtained results, it was found that even small amounts of chelate compounds have a strong impact on the processes under hydrothermal conditions which results in changes in the phase composition of the materials.

Investigation of Multiferroic Properties of Spinel Ferrite (ZnFe2O4) and Ferroelectric (Na0.5Bi0.5TiO3) Composites

2019 ◽  
Vol 201 (1) ◽  
pp. 163-177
Author(s):  
Tanvi Bhasin ◽  
Ashish Agarwal ◽  
Sujata Sanghi ◽  
Manisha Yadav ◽  
Meenal ◽  
...  
Keyword(s):  
Spinel Ferrite ◽  
Xrd Analysis ◽  
Rietveld Analysis ◽  
Phase System ◽  
Reaction Route ◽  
Two Phase ◽  
Low Frequencies ◽  
Thermally Activated ◽  
Universal Power Law ◽  
Constant E

The composites of ZnFe2O4 and Na0.5Bi0.5TiO3 were synthesized by solid state reaction route. XRD analysis revealed the formation of two phase system successfully. Rietveld analysis of XRD data confirm that composites having cubic and rhombohedral corresponding to ferrite and ferroelectric phase respectively. The FESEM-EDX studies disclose that average grain sizes are ranges from 0.2 to 0.4 μm. The dielectric constant (ɛ’) and tanδ both shows dispersion at low frequencies and both increases with temperature due to increase in thermally activated hopping. Conductivity curves of each sample follow the universal power law. M–H plots suggest the paramagnetic behavior of these composites.

Hydrothermal Synthesis and Characterization of LiZr2(PO4)3

2012 ◽  
Vol 512-515 ◽  
pp. 195-198
Author(s):  
Jin Ye Niu ◽  
Zhi Wei Chen ◽  
Cheng Gong Sun ◽  
Liu Feng ◽  
Zheng Min Li ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Ph Value ◽  
Solid Phase ◽  
Low Cost ◽  
Reaction System ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Hydrothermal Conditions

Lithium dizirconium phosphate (LiZr2(PO4)3) possesses good ionic conductivity owing to its unique framework structure and can be used as favorable anode material in Li-ion battery. LiZr2(PO4)3 is commonly prepared by solid phase reaction in which higher temperature is needed and pure LiZr2(PO4)3 without other phases is difficult to obtain in the final products. In this paper, low cost hydrothermal synthesis of pure (LiZr2(PO4)3) was studied. Effects of the hydrothermal conditions (molar ratios of Li+ to ZrOCl2, addition of HF, pH values of reaction system and hydrothermal temperatures) on the phase composition of the products were investigated. The results showed that pure LiZr2(PO4)3 was successfully prepared at lower temperature of 80°C for 24h with the addition of HF when the pH value was adjusted to 5.0 and the molar ratio of Li+ to ZrOCl2 was 0.5 with the concentration of ZrOCl2 as 0.6mol/L. The phases and purity of the final products were characterized by XRD analysis.

scholarly journals Improvement in Slag Resistance of No-Cement Refractory Castables by Matrix Design

Ceramics ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 31-39 ◽  
Author(s):  
Hong Peng ◽  
Jun Liu ◽  
Qinghu Wang ◽  
Yawei Li
Keyword(s):  
Corrosion Resistance ◽  
Strong Impact ◽  
Slag Resistance ◽  
X Ray Diffraction ◽  
Mineral Phases ◽  
Refractory Castables ◽  
Thermodynamic Simulations ◽  
Corrosion Mechanisms ◽  
Matrix Design

The corrosion resistance of spinel containing cement bonded castables has been extensively investigated in the past. However, corrosion of no-cement refractory castables (NCC) has not been widely studied since the use of NCC has been relatively limited up till now. This paper focuses on the slag resistance of NCCs, and the often-used spinel containing low cement castable (LCC) is used as the reference. Three different NCC binders were designed: (i) Al2O3 + MgO (alumina bond), in situ spinel formation; (ii) Al2O3 + SiO2 (microsilica-gel bond), mullite formation; and (iii) Al2O3 + MgO + SiO2 (MgO-SiO2 bond). Slag resistance tests were conducted using the static crucible method with ladle slag. The corrosion mechanisms were studied by means of Scanning Electron Microscopy (SEM/EDS), X-ray Diffraction (XRD), and thermodynamic simulations. The results confirmed that the mineral phases, microstructure, and liquid formation at a high temperature of the refractory materials had a strong impact on the corrosion resistance. The slag resistance was significantly improved when the cement was replaced by the cement-free binders.

Effect of Copper Oxide on the Sintering of Alumina Ceramics

2008 ◽  
Vol 47-50 ◽  
pp. 801-804 ◽  
Author(s):  
Ramesh Singh ◽  
K.L. Aw ◽  
C.H. Ting ◽  
Chou Yong Tan ◽  
Iis Sopyan ◽  
...  
Keyword(s):  
Grain Size ◽  
Copper Oxide ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Alumina Ceramics ◽  
Maximum Hardness ◽  
Air Atmosphere ◽  
Al2o3 Phase ◽  
Α Al2o3 ◽  
Effect Of Copper

The effect of adding small amounts of copper oxide (CuO) on the sintering and mechanical properties of alumina ceramic was studied. Samples were prepared and fired in air atmosphere at temperatures ranging from 1400oC to 1600oC. Sintered samples were characterized to determine phase present, bulk density, hardness and grain size. The results indicated that all the doped samples could be sintered to high density > 3.85 Mgm−3 when compared to the undoped alumina. According to the XRD analysis, the α-Al2O3 phase was not disrupted by the dopant addition. Although the hardness of the CuO-doped material was higher when sintered below 1550°C, the maximum hardness of 21 GPa was measured for the undoped ceramics when sintered at 1600°C. The lower hardness of the doped samples could be attributed to the increased in grain size with increasing sintering temperature.

scholarly journals In Situ Spinel Formation in a Smart Nano-Structured Matrix for No-Cement Refractory Castables

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1403 ◽  
Author(s):  
Dominika Madej ◽  
Karina Tyrała
Keyword(s):  
High Performance ◽  
Interlayer Spacing ◽  
Water Molecules ◽  
Coordination Polyhedra ◽  
Structured Matrix ◽  
Oxygen Coordination ◽  
Refractory Castables ◽  
Ceramic Bond ◽  
Spinel Mgal2o4

The hydration of an equimolar mixture of MgO and Al2O3 nano-powders has been proven to be an effective way to synthesize Mg6Al2CO3(OH)16∙4H2O as a component of a nano-structured matrix and magnesia-alumina spinel precursor for high-performance cement-free corundum-spinel refractory castables. (Mg3)–OH–brucite sites (417 °C) formed initially within the magnesia–alumina hydrating blended paste were replaced with (Mg2Al)–OH and (Mg3)–OH hydrotalcite sites, which were dehydroxylated at 420 °C and 322 °C, respectively. This reorganization was connected with the incorporation of anions and water molecules in the interlayer spacing of hydrotalcite, which was dehydrated at 234 °C. Hence, the thermal decomposition of a nano-structured matrix system containing mainly Mg6Al2CO3(OH)16∙4H2O consists of a complex sequence of dehydration, dehydroxylation and decarbonization, and this finally leads to the formation of inverse spinel MgAl2O4 and periclase MgO through many intermediate stages containing the mixed tetrahedral-octahedral Al phase and MgO-like structure. Hence, the hydraulic bond that primarily existed was replaced by a ceramic bond at a relatively low temperature, i.e., 700 °C, where a spinel was formed. Important changes in oxygen coordination polyhedra around Al3+ in the dehydrated-dehydroxylated hydrotalcite occurred between 600 and 1100 °C.

scholarly journals Effect of an Aluminosilicate Disperse Additive on Behaviors of Autoclave Silicate Materials

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 239
Author(s):  
Viktoriya Nelubova ◽  
Valeria Strokova ◽  
Roman Fediuk ◽  
Mugahed Amran ◽  
Nikolai Vatin ◽  
...  
Keyword(s):  
Gas Adsorption ◽  
Pore Space ◽  
Xrd Analysis ◽  
Mineral Formation ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Maximum Increase ◽  
X Ray ◽  
Binding System ◽  
Full Profile

In this research, a phase formation in CaO–SiO2–Al2O3–H2O binding system under hydrothermal conditions was studied. The novelty of this article lies in the quantitative full-profile X-ray diffraction (XRD) analysis used to determine kinetics of mineral formation in the binder system “lime–granite mineral modifier (GMM)”. The formation of a polymineral system is described in detail, as well as quantitative relationships between mineral composition of newly formed phases and the binding mixture ratios were determined. Phenomenological model of mineral formation in a “lime–GMM” system under hydrothermal conditions was proposed. The results obtained allow the demonstration of this binding system as a binder that is characterized by superposition of hydration and geopolymerization. The properties (strength, density, water absorption, porosity) of compressed autoclave-hardened materials with the addition of a granite modifier introduced instead of part of the sand as an aggregate have been studied. The maximum increase in strength (more than 50%) is observed at a modifier content of 15%. This is due to the formation of a rational composition of neoplasms, the compaction of the structure of the pressed products and the optimization of their pore space, which is confirmed by the data of X-ray diffraction analysis, scanning electron microscopy and the method of gas adsorption.

scholarly journals Coloration and Multi-Functionalization of Polypropylene Fabrics with Selenium Nanoparticles

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2483
Author(s):  
Tarek AbouElmaaty ◽  
Shereen A. Abdeldayem ◽  
Shaimaa M. Ramadan ◽  
Khaled Sayed-Ahmed ◽  
Maria Rosaria Plutino
Keyword(s):  
Antibacterial Activity ◽  
Antibacterial Properties ◽  
Xrd Analysis ◽  
Industrial Applications ◽  
Uv Protection ◽  
Selenium Nanoparticles ◽  
Hydrothermal Conditions ◽  
Color Strength ◽  
Protection Factor ◽  
Tem Analysis

In this study, we developed a new approach for depositing selenium nanoparticles (SeNPs) into polypropylene (PP) fabrics via a one-step process under hydrothermal conditions by using an IR-dyeing machine to incorporate several functionalities, mainly coloration, antibacterial activity and ultraviolet (UV) protection. The formation, size distribution, and dispersion of the SeNPs were determined using X-ray diffraction (XRD), ultraviolet-visible (UV/Vis), transmission electron microscopy (TEM) and the color strength, fastness, antibacterial properties, and UV protection of the treated fabrics were also explored. The UV-Vis spectra and TEM analysis confirmed the synthesis of spherical well-dispersed SeNPs and the XRD analysis showed the successful deposition of SeNPs into PP fabrics. The obtained results demonstrate that the SeNPs-PP fabrics is accompanied by a noticeable enhancement in measurements of color strength, fastness, and UV-protection factor (UPF), as well as excellent antibacterial activity. Viability studies showed that SeNPs-PP fabrics are non-toxic against wi-38cell line. In addition, the treated SeNPs-PP fabrics showed an increase in conductivity. The obtained multifunctional fabrics are promising for many industrial applications such as the new generation of curtains, medical fabrics, and even automotive interior parts.

Phase-Selective Synthesis of a Silicoaluminophosphate Molecular Sieve with 3-Aminopropyltriethoxysilane as the Silica Source

2014 ◽  
Vol 1061-1062 ◽  
pp. 109-111
Author(s):  
Ya Dong Bai ◽  
Hai Rong Zhang ◽  
Pei Wan Bai ◽  
Hong Yan Liu ◽  
Shen Hua Han ◽  
...  
Keyword(s):  
Amorphous Phase ◽  
Molecular Sieves ◽  
Molecular Sieve ◽  
Xrd Analysis ◽  
Similar Reaction ◽  
Selective Synthesis ◽  
Hydrothermal Conditions ◽  
Silicon Source ◽  
Silica Source ◽  
Phase Selectivity

Silicoaluminophosphate (SAPO) molecular sieves with CHA and AFI structures have been synthesized under hydrothermal conditions from similar reaction mixtures using 3-Aminopropyl-triethoxysilane as silicon source. The XRD analysis indicated that the phase selectivity could follow the sequence of SAPO-34→SAPO-34+ SAPO-5→SAPO-5 →amorphous phase with increasing the amount of the silicon source. The phase selectivity can be explained by the increasing alkalinity of the medium with the 3-Aminopropyltriethoxysilane concentration.

Trends in Periprosthetic Knee Infection and Associated Costs: A Population-Based Study Using National Data

2020 ◽  
Author(s):  
Robert Brochin ◽  
Jashvant Poeran ◽  
Khushdeep S. Vig ◽  
Aakash Keswani ◽  
Nicole Zubizarreta ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Length Of Stay ◽  
Knee Arthroplasty ◽  
Trend Test ◽  
Strong Impact ◽  
Hospitalization Costs ◽  
Teaching Status ◽  
Increasing Trend ◽  
Total Knee ◽  
Increasing Trends

AbstractGiven increasing demand for primary knee arthroplasties, revision surgery is also expected to increase, with periprosthetic joint infection (PJI) a main driver of costs. Recent data on national trends is lacking. We aimed to assess trends in PJI in total knee arthroplasty revisions and hospitalization costs. From the National Inpatient Sample (2003–2016), we extracted data on total knee arthroplasty revisions (n = 782,449). We assessed trends in PJI prevalence and (inflation-adjusted) hospitalization costs (total as well as per-day costs) for all revisions and stratified by hospital teaching status (rural/urban by teaching status), hospital bed size (≤299, 300–499, and ≥500 beds), and hospital region (Northeast, Midwest, South, and West). The Cochran–Armitage trend test (PJI prevalence) and linear regression determined significance of trends. PJI prevalence overall was 25.5% (n = 199,818) with a minor increasing trend: 25.3% (n = 7,828) in 2003 to 28.9% (n = 19,275) in 2016; p < 0.0001. Median total hospitalization costs for PJI decreased slightly ($23,247 in 2003–$20,273 in 2016; p < 0.0001) while median per-day costs slightly increased ($3,452 in 2003–$3,727 in 2016; p < 0.0001), likely as a function of decreasing length of stay. With small differences between hospitals, the lowest and highest PJI prevalences were seen in small (≤299 beds; 22.9%) and urban teaching hospitals (27.3%), respectively. In stratification analyses, an increasing trend in PJI prevalence was particularly seen in larger (≥500 beds) hospitals (24.4% in 2003–30.7% in 2016; p < 0.0001), while a decreasing trend was seen in small-sized hospitals. Overall, PJI in knee arthroplasty revisions appears to be slightly increasing. Moreover, increasing trends in large hospitals and decreasing trends in small-sized hospitals suggest a shift in patients from small to large volume hospitals. Decreasing trends in total costs, alongside increasing trends in per-day costs, suggest a strong impact of length of stay trends and a more efficient approach to PJI over the years (in terms of shorter length of stay).

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