scholarly journals Comparative Study of Cold Sintering Process and Autoclave Thermo-Vapor Treatment on a ZnO Sample

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 71
Author(s):  
Yurii Ivakin ◽  
Andrey Smirnov ◽  
Anastasia Kholodkova ◽  
Alexander Vasin ◽  
Mikhail Kormilicin ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Aqueous Medium ◽  
Ammonium Chloride ◽  
Zinc Acetate ◽  
Crystal Size ◽  
Solid Phase ◽  
Sintering Process ◽  
Mechanical Pressure ◽  
Average Grain Size ◽  
Phase Mobility

Analysis of scanning electron microscopy images was used to study the changes in the crystal size distribution of ZnO, which occurred during its processing in an aqueous medium at 220–255 °C and an equilibrium vapor pressure in an autoclave. The results were compared with those of ZnO placed in a die for treatment under similar conditions supplemented with mechanical pressure application in the cold sintering process. In both cases, ZnO was treated in the presence of an activating additive: either zinc acetate or ammonium chloride. During autoclaving, a powder consisting of fine ZnO monocrystals was obtained, while the cold sintering process led to ceramics formation. Under vapor pressure and mechanical pressure, the aqueous medium affected ZnO transformation by the same mechanism of solid-phase mobility activation due to the additives’ influence. The higher the content of additives in the medium, and the higher the mechanical pressure, the more pronounced activating effect was observed. Mass transfer during the cold sintering process occurred mainly by the coalescence of crystals, while without mechanical pressure, the predominance of surface spreading was revealed. In the initial ZnO powder, the average crystal size was 0.193 μm. It grew up to 0.316–0.386 μm in a fine-crystalline powder formed in the autoclave and to an average grain size of 0.244–0.799 μm in the ceramics, which relative density reached 0.82–0.96. A scheme explaining the influence of an aqueous medium on the solid-phase mobility of ZnO structure was proposed. It was found that the addition of 7.6 mol% ammonium chloride to the reaction medium causes the processes of compaction and grain growth similar to those observed in ZnO Cold Sintering Process with the addition of 0.925 mol% zinc acetate.

Synthesis of 1,2-bis(3,4-dicyanophenoxymethyl)benzene and binuclear zinc phthalocyanines of clamshell and ball types

2003 ◽  
Vol 07 (03) ◽  
pp. 162-166 ◽  
Author(s):  
Alexander Yu. Tolbin ◽  
Alexey V. Ivanov ◽  
Larisa G. Tomilova ◽  
Nikolai S. Zefirov
Keyword(s):  
Microwave Irradiation ◽  
Zinc Acetate ◽  
Solid Phase ◽  
Large Excess ◽  
Type Reaction ◽  
Zinc Phthalocyanines

A novel 1,2-bis(3,4-dicyanophenoxymethyl)benzene was synthesized from 1,2-bis-(hydroxymethyl)benzene and 4-nitrophthalodinitrile. Its condensation with 4-tert-butylphthalodinitrile results in a binuclear phthalocyanine of clamshell type. Reaction of bisphthalodinitrile with a large excess of zinc acetate gives rise to a binuclear phthalocyanine of ball type (33% yield). The successful syntheses of these binuclear phthalocyanines were carried out by microwave irradiation and solid phase methods.

Transport Properties of B-, P-Doped and Undoped 50 kHz PECVD Microcrystalline Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
M.A. Hachicha ◽  
Etienne Bustarret
Keyword(s):  
Grain Size ◽  
Hall Mobility ◽  
Solid Phase ◽  
Grazing Angle ◽  
Dc Conductivity ◽  
X Ray Diffraction ◽  
Crystalline Fraction ◽  
Average Grain Size ◽  
20 Nm ◽  
Solid Phase Density

AbstractUndoped 500 nm-thick silicon layers with a crystalline fraction around 95% and an average grain size of 20 nm have been deposited at 350°C by 50 kHz triode PECVD in a H2/SiH4 mixture, in the presence of a magnetic field. Their room temperature (rt) dc conductivity μrt is 0.03 Δ−1cm−1 for a Hall mobility of 0.8 cm 2V−1s−1.The study by SIMS, infrared absorption, grazing angle x-ray diffraction and Raman scattering spectroscopies of the doped samples shows how the crystalline fraction and the grain size drop as the B2H6/SiH4 and PH3/SiH4 volumic ratios increase from 10 ppm to 1%.The rt dc conductivity reaches 2 Δ−1 cm−1 (Hall mobility: 15 cm2V−ls−1) for a solid phase density of 1019 cm−3 boron atoms, and 30 Δ−1cm−1 (Hall mobility: 55 cm2V−ls−1) at the maximum P incorporation of 8 × 1020cm−3.

scholarly journals Synthesis and Sintering of Nanostructured ZrB2-SiC Composite

2021 ◽  
Vol 59 (7) ◽  
pp. 439-444
Author(s):  
In-Jin Shon
Keyword(s):  
Fracture Toughness ◽  
Melting Point ◽  
Coefficient Of Thermal Expansion ◽  
High Melting ◽  
High Melting Point ◽  
Mechanical Pressure ◽  
Simultaneous Application ◽  
Brittle Ductile Transition ◽  
Average Grain Size ◽  
Improve Fracture Toughness

ZrB2 is considered a candidate material for ultra-high temperature ceramics because of its high thermal conductivity, high melting point, and low coefficient of thermal expansion. Despite these attractive properties, applications of ZrB2 are limited by its low fracture toughness below the brittle-ductile transition temperature. To improve its ductile properties, the approach universally utilized has been to add a second material to form composites and fabricate nanostructured materials. One example of this is the adding of SiC to ZrB2 to improve fracture toughness. SiC has low density, excellent resistance to oxidation in air, and a high melting point. Therefore, SiC may be a promising additive as a reinforcing material for ZrB2-based composites. A dense nanostructured ZrB2-SiC composite was rapidly synthesized and sintered by high-frequency induction heating (HFIH) within 4 min in one step, from mechanically activated powders of ZrC, 2B and Si. Simultaneous combustion synthesis and consolidation were accomplished using the combination of current and mechanical pressure. A highly dense ZrB2-SiC composite with a relative density of up to 98.4% was fabricated using the simultaneous application of 70 MPa pressure and an induced current. The mechanical properties (toughness and hardness) and the average grain size of the composite were investigated.

scholarly journals Microstructure features of the BST/(Mg, Ln)-ceramic

2021 ◽  
pp. 2160005
Author(s):  
K. P. Andryushin ◽  
A. V. Nagaenko ◽  
S. V. Khasbulatov ◽  
L. A. Shilkina ◽  
E. V. Glazunova ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Functional Materials ◽  
Ceramic Technology ◽  
Phase Synthesis ◽  
Fine Grained ◽  
Average Grain Size ◽  
Crystallite Sizes ◽  
Fine Grained Structure

Solid solutions of the composition Ba[Formula: see text](Mg, Ln)[Formula: see text]Sr[Formula: see text]TiO3 ([Formula: see text] = 0.01; 0.025; 0.04; [Formula: see text] = 0.20; 0.50; 0.80; Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tu, Yb) were prepared by two-stage solid-phase synthesis followed by sintering using conventional ceramic technology. The influence of rare-earth elements on the microstructure of the prepared ceramic samples was investigated. It was found that regardless of the type of modifiers introduced, the grain landscape of the studied solid solutions with different amounts of SrTiO3 is refined (in the initial system, the average grain size, [Formula: see text], at [Formula: see text] = 0.20 is 6 [Formula: see text]m; at [Formula: see text] = 0.50 is 4 [Formula: see text]m; at [Formula: see text] = 0.80 is 18 [Formula: see text]m) to crystallite sizes not exceeding (2–3) [Formula: see text]m, and compacted. The using of mechanical activation procedures leads to an even greater decrease in the size and an increase in the density of ceramics. The increasing in the concentration of modifiers in each group (within the considered range of dopant variation) against the background of such a fine-grained structure has little effect on the dynamics of changes in [Formula: see text]. It is concluded that it is advisable to use the data obtained in the development of functional materials based on BST/(Mg, Ln) and devices with the participation of these compositions.

Microstructure of Semi-Solid Extruded Copper Alloy after Heat Treatment

2019 ◽  
Vol 285 ◽  
pp. 146-152
Author(s):  
Nai Yong Li ◽  
Han Xiao ◽  
Chi Xiong ◽  
De Hong Lu ◽  
Rong Feng Zhou
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Copper Alloy ◽  
Treatment Time ◽  
Solid Phase ◽  
Treatment Temperature ◽  
Primary Phase ◽  
Holding Time ◽  
Average Grain Size ◽  
Semi Solid

The semi-solid extruded ZCuSn10P1 copper alloy were annealed at different temperatures and time. The influences of heat treatment temperature and holding time on the microstructure of semi-solid ZCuSn10P1 copper alloy were investigated. The results show that with the increase of heat treatment temperature, the morphology of the semi-solid microstructure was improved, the sharp angle around the primary phase α-Cu and the liquid droplets were reduced. With the increase of heat treatment time, the solid-liquid segregation of the semi-solid structure was improved. The average grain size of the solid phase increased with the increasing of the holding time. After heat treatment, the solid solubility of the primary phase α-Cu increased, and the Sn and P elements in the liquid phase continued to diffuse to the primary phase α-Cu. The microstructure of semi-solid copper alloy was the most uniform after heat treatment at 350°C for 120 min.

Simultaneous Synthesis and Consolidation of Nanostructured ZrB2–ZrO2 Composite

2020 ◽  
Vol 20 (7) ◽  
pp. 4349-4352
Author(s):  
Seong-Eun Kim ◽  
Jin-Kook Yoon ◽  
In-Jin Shon
Keyword(s):  
Mechanical Properties ◽  
Combustion Synthesis ◽  
High Frequency ◽  
Combined Effects ◽  
Induced Current ◽  
Mechanical Pressure ◽  
Simultaneous Application ◽  
Average Grain Size ◽  
One Step ◽  
Simultaneous Synthesis

A dense nanostructured 2ZrB2–ZrO2 composite was synthesized by the high-frequency inductionheated combustion synthesis (HFIHCS) method within 2 min in one step from mechanically activated powders of 2B2O3 and 3Zr. Simultaneous combustion synthesis and densification were accomplished under the combined effects of the induced current and mechanical pressure. A highly dense 2ZrB2–ZrO2 composite with relative density of up to 95.5% was produced under the simultaneous application of a pressure of 80 MPa and the induced current. The average grain size and mechanical properties (hardness and fracture toughness) of the composite were investigated.

scholarly journals Mechanical Properties and Microstructure of W-6Ni-4Co Alloy by a Two-Step Sintering Process

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 680 ◽  
Author(s):  
Hongfeng Dong ◽  
Peiyou Li ◽  
Taotao Ai ◽  
Wenhu Li
Keyword(s):  
Mechanical Properties ◽  
Mechanical Alloying ◽  
Solid Phase ◽  
Particle Sizes ◽  
Sintering Process ◽  
Dwelling Time ◽  
Milled Powders

The mechanical properties and microstructure of W-6Ni-4Co alloy through solid phase sintering and two-step sintering process were investigated. The results demonstrated that the particle sizes of W-6Ni-4Co alloy milled powders increased firstly and decreased later during a mechanical alloying process. The shape of alloy milled powders affected that of grains in alloy by solid phase sintering. The shape of W-rich particles in the alloys changed from stripes to network, to polygonal and to subsphaeroidal finally during two-step sintering process. The mechanical properties could be attributed to the densification and microstructure of alloys, and increased during two-step sintering with short dwelling time.

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