scholarly journals Fine Biocompatible Powders Synthesized from Calcium Lactate and Ammonium Sulfate

Ceramics ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 391-396
Author(s):  
Maksim Kaimonov ◽  
Tatiana Shatalova ◽  
Yaroslav Filippov ◽  
Tatiana Safronova
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Ammonium Sulfate ◽  
Calcium Oxide ◽  
Glass Ceramic ◽  
Calcium Sulfate ◽  
Calcium Lactate ◽  
Inorganic Glass ◽  
Heat Treated ◽  
Tiny Amount

Fine biocompatible powders with different phase compositions were obtained from a 0.5 M solution of ammonium sulfate (NH4)2SO4 and calcium lactate Ca(C3H5O3)2. The powder after synthesis and drying at 40 °C included calcium sulfate dehydrate CaSO4·2H2O and calcite CaCO3. The powder after heat treatment at 350 °C included β-hemihydrate calcium sulfate β-CaSO4·0.5H2O, γ-anhydrite calcium sulfate γ-CaSO4 and calcite CaCO3. The phase composition of powder heat-treated at 600 °C was presented as β-anhydrate calcium sulfate β-CaSO4 and calcite CaCO3. Increasing the temperature up to 800 °C leads to the sintering of a calcium sulfate powder consisting of β-anhydrite calcium sulfate β-CaSO4 main phase and a tiny amount of calcium oxide CaO. The obtained fine biocompatible powders of calcium sulfate both after synthesis and after heat treatment at temperature not above 600 °C can be recommended as a filler for producing unique composites with inorganic (glass, ceramic, cement) or polymer matrices.

OPTIMIZATION of DYNAMIC CH4 GAS HEAT TREATMENT OF NANOCRYSTALLINE STRONTIUM HEXAFERRITE

2012 ◽  
Vol 05 ◽  
pp. 752-759 ◽  
Author(s):  
R. DEHGHAN ◽  
S. A. SEYYED EBRAHIMI ◽  
H. R. KOOHDAR
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Strontium Hexaferrite ◽  
Gas Flows ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Size And Morphology ◽  
Magnetic Nature

In this research the influence of dynamic CH 4 heat treatment on Sr -hexaferrite has been investigated. With the gas heat treatment, the phase composition, particles size and the morphology of Sr -hexaferrite change significantly. Due to this, the hard magnetic nature of the material changes from hard to soft. The strontium hexaferrite powder was prepared by conventional route with calcination of the mixture of strontium carbonate and hematite at 1100°C for 1 hour. Then the resultant Sr -hexaferrite was isothermally heat treated in methane dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions were obtained at 950°C and 15CC/min flow for 0.5 hour. The effects of gas heat treatment on the phase composition and the particles size and morphology were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibration Sample Magnetometery (VSM) techniques. The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant iron was also measured below 50nm.

OPTIMIZATION OF Sr-HEXAFERRITE DYNAMIC GASEOUS HEAT TREATMENT BY CARBON MONOXIDE

2008 ◽  
Vol 22 (18n19) ◽  
pp. 3133-3138
Author(s):  
A. YOURDKHANI ◽  
S. A. SEYYED EBRAHIMI ◽  
H. R. KOOHDAR
Keyword(s):  
Heat Treatment ◽  
Carbon Monoxide ◽  
Phase Composition ◽  
Strontium Hexaferrite ◽  
Gas Flows ◽  
Hard Magnetic Material ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Size And Morphology ◽  
Magnetic Nature

In this research the influence of dynamic carbon monoxide heat treatment on Sr -hexaferrite has been investigated. Sr -hexaferrite is a hard magnetic material which under gaseous heat treatment, its phase composition and particles size and morphology change significantly. Due to these changings, the magnetic nature of the material changes from hard to soft. Strontium hexaferrite was prepared by conventional route with calcination of Sr -carbonat and hematite at 1100°C for 1 hour. Then Sr -hexaferrite was isothermally heat treated in carbon monoxide dynamic atmosphere at various temperatures and gas flows for different times. The rate of heating and cooling were 10°C/min. The optimum conditions was obtained at 850°C and 20cc/min flow for 0.5 hour. The effect of gaseous heat treatment on phase composition and particles size and morphology characterized by XRD and SEM. The results show the decomposition of Sr -hexaferrite and reduction of the resultant hematite mainly to iron. The crystallite size of the resultant powder was also measured below 50nm.

scholarly journals Alumina silicate glass-ceramic materials for electrical purposes

2020 ◽  
Vol 120 ◽  
pp. 174-185
Author(s):  
O. V. Savvova ◽  
G. K. Voronov ◽  
S. A. Ryabinin ◽  
E. Yu. Fedorenko ◽  
V. D. Timofeev
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Electrical Properties ◽  
Silicate Glass ◽  
Glass Ceramic ◽  
Breakdown Strength ◽  
Chemical Properties ◽  
Ceramic Materials ◽  
Silicate System ◽  
Glass Ceramic Materials

The prospects for use of glass-ceramic materials as electrical products were analyzed. The priority of a self-organized macro- and nanostructure formation of the glass-ceramic materials under conditions of low-temperature heat treatment to ensure their high physical and chemical properties was shown. The choice of an alumina silicate system of materials for obtaining high-strength glass-ceramic materials with improved electrical properties was substantiated, taking into account the aspects of energy saving. The technological modes of cooking, forming and heat treatment of glass-ceramic materials were determined. Resistance, dielectric constant and dielectric loss tangent at 106 Hz were measured using an E6-13A teraometer on a trielectrode system at a temperature of +29 °C and a DE-5000 RLC meter. Electric strength (Em) and cold crushing strength were determined according to GOST 24409-80. Tensile strength according to GOST 32281.1-2013 (EN 1288-1: 2000). The decisive influence on the electrical properties of glass-ceramic materials the crystalline phases of α-cordierite, β-spodumene or lithium disilicate, as well as the residual glass phase composition has been established. The structure influence of the alumina silicate glass-ceramic materials on the provision of their electrical (tgδ∙104 = 70 ÷ 80; ε = 8.0 ÷ 9.3 (at f = 106 Hz); lg ρv = 12.9 ÷ 15.0 (ρv, Ohm·cm at Т = 20 °C) and mechanical (K1C = 3.15 ÷ 4.3 МPа∙м1/2; σ comp = 630 ÷ 700 МPа, σbend = 300 ÷ 350 МPа; KCU = 4.8 ÷ 5.9 kJ/m2) properties. It was found that, the defining condition for the developed glass-ceramic materials use as insulating materials under repeated exposure to high-temperature operations is their high breakdown strength Em = 37 ÷ 42 MV/m and thermal shock resistance due to low TCLE (α∙107 = 21.5 ÷ 31.8 deg-1). The influence of phase composition and structure of the alumina silicate glass-ceramic materials on their electrical and mechanical properties was analyzed. A comparative assessment of the known ceramic and glass-ceramic materials for electrical purposes has made it possible to establish the feasibility of using the developed materials as substrates in the design of a hybrid integrated circuit, vacuum-tight shell and capacitor dielectrics.

Microstructure and Phase Composition of (Ce, Mg)-PSZ Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1194-1196
Author(s):  
Zhi Ping Shen ◽  
Shu Cai ◽  
Zhen Dong
Keyword(s):  
Heat Treatment ◽  
Phase Composition ◽  
Monoclinic Phase ◽  
Processing Method ◽  
Nanoporous Structure ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
X Ray ◽  
Heat Treated

Magnesia, ceria partially stabilized zirconia (Ce,Mg)-PSZ ceramics with net shape microstructure are prepared using a processing method similar to that of conventional Mg-PSZ ceramics, then heat-treated at 1500°C for different time. Microstructure and phase composition of (Ce, Mg)-PSZ samples with different amount of CeO2 doped were investigated using SEM and X-ray diffraction. The addition of CeO2 could impede the formation of monoclinic phase and inhibit the growth of cubic grains. A microstructure with net-shape cubic grains, in which tetragonal precipitates interweave to a nanoporous structure is obtained by adding 4∼8 mol% CeO2 in 10mol% MgO doped zirconia matrix and then heat treatment at 1500°C for different time. The precipitate morophology might be related with the addition of CeO2 and the heat treatment temperatures.

scholarly journals Tailoring the Glass Composition to Increase the Thermal Stability without Impacting the Crystallization Behavior of Oxyfluorophosphate Glass

Ceramics ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 148-159
Author(s):  
Nirajan Ojha ◽  
Iuliia Dmitrieva ◽  
Wilfried Blanc ◽  
Laeticia Petit
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Glass Ceramic ◽  
Glass Composition ◽  
Glass Ceramics ◽  
Glass Network ◽  
Thermally Stable ◽  
Heat Treated ◽  
The Impact ◽  
Thermal Stability Of

Even though the (75 NaPO3-25 CaF2) (in mol%) glass can be heat-treated into transparent glass-ceramic with Er3+ doped CaF2 crystals precipitating in the volume of the glass during heat-treatment, this glass was found to be a poor glass former, limiting its use as upconverter under 975 nm pumping. In this study, the impact of the glass composition on the thermal, optical and structural properties of the glass was investigated in order to understand how the glass composition can be tailored for the development of thermally stable upconverter glass-based material. The addition of MgO, Fe2O3 and Al2O3 in the NaPO3-CaF2 glass system increases the thermal stability of glass due to the depolymerization of the glass network. However, the changes in the glass composition also impacted on the nucleation and growth process. Indeed, CaF2 and other crystals were found in the newly developed glasses after heat-treatment leading to glass-ceramics with lower intensity of upconversion than the (75 NaPO3-25 CaF2) glass-ceramic used as a reference. Glasses were also prepared with different concentrations of Er2O3 and ErF3. These glasses were found to be promising as not only are they thermally stable, but they also exhibit green and red emission with high intensity under 975 nm pumping due to Er3+ clustering.

SYNTHESIS OF NANOSIZE SILICON CARBIDE POWDER BY CARBOTHERMAL REDUCTION OF SiO2

2012 ◽  
Vol 05 ◽  
pp. 263-269 ◽  
Author(s):  
M. DEHGHANZADEH ◽  
A. ATAIE ◽  
S. HESHMATI-MANESH
Keyword(s):  
Heat Treatment ◽  
Silicon Carbide ◽  
Phase Composition ◽  
Crystalline Silicon ◽  
High Energy ◽  
Nano Particles ◽  
Process Conditions ◽  
Sample Heat ◽  
State Reduction ◽  
Heat Treated

A mixture of silicon carbide nano-particles and nano-whiskers has been synthesized through solid state reduction of silica by graphite employing high energy planetary ball milling for 25 h and subsequent heat treatment at 1300-1700°C in dynamic argon atmosphere. Effects of process conditions on the thermal behavior, phase composition and morphology of the samples were investigated using DTA/TGA, XRD and SEM, technique, respectively. DTA/TGA analysis shows that silicon carbide starts to form at ~ 1250°C. Analysis of the XRD patterns indicates that the phase composition of the sample heat treated at 1300°C for 2 h mainly consists of SiO 2 together with small amount of β- SiC . Nano-crystalline silicon carbide phase with a mean crystallite size of 38 nm was found to be dominate phase on heat treatment temperature at ~ 1500°C. Substantial SiO 2 was still remained in the above sample. SEM studies reveal that the sample heat treated at 1500°C for 2 h contains nano-particles and nano-whisker of β- SiC with a mean diameter of almost ~ 85 nm. The results obtained were also showed that the characteristics of the synthesized SiC particles strongly depend on the mechanical activation and heat treatment conditions.

Preparation and Characterization of Superionic Conductive Li2O-Al2O3-La2O3-TiO2-P2O5 Glass-Ceramics

2012 ◽  
Vol 509 ◽  
pp. 314-320 ◽  
Author(s):  
Hong Ping Chen ◽  
Hai Zheng Tao ◽  
Qi De Wu ◽  
Xiu Jian Zhao
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Ion ◽  
Treatment Temperature ◽  
Total Conductivity ◽  
Scanning Calorimetry ◽  
Structural Morphology ◽  
Heat Treated ◽  
Different Temperatures

Li2O-Al2O3(La2O3)-TiO2-P2O5 glass-ceramics were fabricated through heat-treatment of the original glass. The differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical workstation were employed to study the structural, morphology and electrical properties of the samples heat-treated at different temperatures. The results showed that: the glass-ceramics consist of the dominating LiTi2(PO4)3 phases, trifle AlPO4, TiO2 and unknown phases. With the heat-treatment temperature increasing from 700 °C to 1100 °C, the structure of glass-ceramic become denser and grain grew, lithium ion conductivity increased quickly and subsequent cut down gradually. While the specimen was obtained by crystallization at 900 °C for 12 h, the total conductivity of glass-ceramic material come up to the maximum (5.85 ×10-4 S•cm-1) at 25 °C. This inorganic solid electrolyte has a potential application in lithium batteries or other devices.

scholarly journals Preparation of chemical waste germanium concentrates for disposal

2020 ◽  
Vol 63 (8) ◽  
pp. 73-79
Author(s):  
Igor N. Tanutrov ◽  
◽  
Marina N. Sviridova ◽  
Keyword(s):  
Heat Treatment ◽  
Calcium Sulfate ◽  
Water Molecules ◽  
Chemical Processing ◽  
Strengthening Effect ◽  
Chemical Waste ◽  
Calcium Hypochlorite ◽  
Calcium Sulfate Dihydrate ◽  
Heat Treated ◽  
Free Moisture

The composition of waste from chemical processing of germanium concentrates (WCGC) is characterized by the presence of germanium compounds insoluble in acids, as well as significant amounts of toxic impurities. The main phase components are calcium sulfate dihydrate and four-water calcium hypochlorite. Thermographic research on heating samples of WCGC at 200 оС in the air found that their heat treatment is accompanied by two endothermic effects corresponding to two successive stages of dehydration at exposure from the beginning of heat treatment to 30 minutes with the removal of free moisture and from 30 to 90 minutes with the removal of 1.5 water molecules from gypsum and 4 water molecules – from calcium hypochlorite. X-ray phase analysis revealed that the heat-treated samples form calcium sulfate hemihydrate and dehydrated calcium hypochlorite. The presence of these compounds gives a strengthening effect when moistened due to the re-formation of crystallohydpates. In laboratory conditions, options for pelletizing pre-crushed mixtures of heat-treated WCGC and coke using pelletizing and briquetting methods have been tested. The humidity, density, bulk weight and strength of pellets and briquettes for compression and impact were determined immediately after pelletizing, seven-hour exposure and drying at 105 оС. The research results confirm the possibility of obtaining a material suitable for effective utilization of waste from chemical processing of germanium concentrates.

scholarly journals Effect of Heat Treatment on the Phase Composition, Microstructure and Mechanical Properties of Al0.6CrFeCoNi and Al0.6CrFeCoNiSi0.3 High-Entropy Alloys

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 974 ◽  
Author(s):  
Lijia Chen ◽  
Kirsten Bobzin ◽  
Zheng Zhou ◽  
Lidong Zhao ◽  
Mehmet Öte ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Transition ◽  
Heat Treatment ◽  
Phase Composition ◽  
Elevated Temperatures ◽  
Intermetallic Phase ◽  
Phase Changes ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Heat Treated

High-entropy alloys exhibit some interesting mechanical properties including an excellent resistance against softening at elevated temperatures. This gives high-entropy alloys (HEAs) great potential as new structural materials for high-temperature applications. In a previous study of the authors, oxidation behavior of Al0.6CrFeCoNi and Al0.6CrFeCoNiSi0.3 high-entropy alloys at T = 800 °C, 900 °C and 1000 °C was investigated. Si-alloying was found to increase the oxidation resistance by promoting the formation of a continuous Al2O3 layer, avoiding the formation of AlN at T = 800 °C. Obvious phase changes were identified in the surface areas of both alloys after the oxidation experiments. However, the effects of heat treatment and Si-alloying on the phase transition in the bulk were not investigated yet. In this study, Al0.6CrFeCoNi and Al0.6CrFeCoNiSi0.3 high-entropy alloys were heat-treated at T = 800 °C and T = 1000 °C to investigate the effect of heat treatment on microstructure, phase composition and mechanical properties of both alloys. The results show that alloying Al0.6CrFeCoNi with Si caused a phase transition from dual phases consisting of BCC and FCC to a single BCC phase in an as-cast condition. Furthermore, increased hardness for as-cast and heat-treated samples compared with the Al0.6CrFeCoNi alloy was observed. In addition, the heat treatment facilitated the phase transition and the precipitation of the intermetallic phase, which resulted in the change of the mechanical properties of the alloys.

Effects of Ingredients and Post-Heat Treatment on Phase Transformation and Structure of Bioactive Composite Coatings

2007 ◽  
Vol 280-283 ◽  
pp. 1619-1622
Author(s):  
Mu Qin Li ◽  
Da Shan Shang ◽  
Chen Ma ◽  
Shi Qin Yang
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Phase Composition ◽  
Composite Coatings ◽  
Thermal Spraying ◽  
Post Heat Treatment ◽  
Working Layer ◽  
Structure Changes ◽  
Heat Treated ◽  
Tio2 Rutile

Bioactive composite coatings containing sub-layer and working-layer with different ingredients were prepared using subsonic thermal spraying technology and then heat-treated at 700°C for 1h. Two types of bioglasses, named BG1 and BG2, and Y2O3 were used as additives of the sublayer and working layer respectively. Phase transformation and structure changes of the coatings were investigated with XRD, DSC and SEM. Results showed that the phases of as-sprayed Ti/BG1 sub-layer were TiN, TiO2 (rutile and anatase), etc. Post-heat treatment changed the phase composition. TiN and anatase transformed into rutile and some new phases generated, which often enriched at pores and cracks. In the working-layer, part of nano-hydroxyapatite powders decomposed during coating preparation. Y2O3 impaired the decomposition to some extent and BG2 enhanced greatly. Post-heat treatment increased the crystallinity of all coatings effectively. The analysis of TG-DSC showed that BG2 added in working-layer crystallized at 700°

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