scholarly journals One-Step Sintering Process for the Production of Magnetocaloric La(Fe,Si)13-Based Composites

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 112
Author(s):  
Xi-Chun Zhong ◽  
Xu-Tao Dong ◽  
Jiao-Hong Huang ◽  
Cui-Lan Liu ◽  
Hu Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mass Fraction ◽  
Reaction Diffusion ◽  
Entropy Change ◽  
Sintering Process ◽  
Sintering Time ◽  
Free Sample ◽  
One Step ◽  
Binder Free ◽  
Thermal Conductivity Λ

A one-step sintering process was developed to produce magnetocaloric La(Fe,Si)13/Ce-Co composites. The effects of Ce2Co7 content and sintering time on the relevant phase transformations were determined. Following sintering at 1373 K/30 MPa for 1–6 h, the NaZn13-type (La,Ce)(Fe,Co,Si)13 phase formed, the mass fraction of α-Fe phase reduced and the CeFe7-type (La,Ce)(Fe,Co,Si)7 phase appeared. The mass fraction of the (La,Ce)(Fe,Co,Si)7 phase increased, and the α-Fe phase content decreased with increasing Ce2Co7 content. However, the mass fraction of the (La,Ce)(Fe,Co,Si)7 phase reduced with increasing sintering time. The EDS results showed a difference in concentration between Co and Ce at the interphase boundary between the 1:13 phase and the 1:7 phase, indicating that the diffusion mode of Ce is reaction diffusion, while that of Co is the usual vacancy mechanism. Interestingly, almost 100 % single phase (La,Ce)(Fe,Co,Si)13 was obtained by appropriate Ce2Co7 addition. After 6 h sintering at 1373 K, the Ce and Co content in the (La,Ce)(Fe,Co,Si)13 phase increased for larger Ce2Co7 content. Therefore, the Curie temperature increased from 212 K (binder-free sample) to 331 K (15 wt.% Ce2Co7 sample). The maximum magnetic entropy change (−∆SM)max decreased from 8.8 (binder-free sample) to 6.0 J/kg∙K (15 wt.% Ce2Co7 sample) under 5 T field. High values of compressive strength (σbc)max of up to 450 MPa and high thermal conductivity (λ) of up to 7.5 W/m∙K were obtained. A feasible route to produce high quality La(Fe,Si)13 based magnetocaloric composites with large MCE, good mechanical properties, attractive thermal conductivity and tunable TC by a one-step sintering process has been demonstrated.

Experimental Research on Utilization of Steel Rolling Sludge in Sintering Process

2013 ◽  
Vol 11 (1) ◽  
pp. 283-291 ◽  
Author(s):  
Haochuan Zhao ◽  
Wenqi Zhong ◽  
Guanwen Zhou ◽  
Yingjuan Shao ◽  
Tiancai Wang ◽  
...  
Keyword(s):  
Air Pollutants ◽  
Mass Fraction ◽  
Sintering Temperature ◽  
Average Concentration ◽  
Suction Pressure ◽  
Sintering Process ◽  
Gas Temperature ◽  
Steel Rolling ◽  
Sinter Quality ◽  
Sintering Time

Abstract A quantity of steel rolling sludge (SRS) produced in the rolling mill is harm to the environment and difficult to dispose. This article is devoted to study on utilization of SRS in sintering process. A sinter pot system with capacity of 75 kg was established. The sintering time, the flue gas temperature, the sintering temperature and the suction pressure in sintering process were measured. Besides the sinter quality, air pollutants discharged from the sintering process with the mass fraction of SRS ranging from 0 to 3% was investigated. The results showed that the CO2 concentration is corresponding to the sintering process, the SO2 concentration has a self-sustaining characteristic and the NOX concentration maintains stability. Increase in mass fraction of SRS leads to the decrease of sintering temperature, particle size, tumbler index and basicity of the sinter. Besides, the sintering time and the average concentration of NOX decrease first and then increase, while the suction pressure appears an opposite trend with increasing mass fraction of SRS. Moreover, the average concentration of CO2 and SO2 both decrease with increasing mass fraction of SRS, and the fuel consumption per sinter produced is the least when the mass fraction of SRS is 2%. Therefore, when the mass fraction of SRS was 2%, the sintering process had the best performance in consideration of sinter quality, emission of air pollutants and behaviors in sintering process.

scholarly journals Effect of Phenolic Resin on Micropores Development in Carbon Foam with High Performance

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1213 ◽  
Author(s):  
Alei Dang ◽  
Zhao Zhao ◽  
Chen Tang ◽  
Chenglin Fang ◽  
Siyuan Kong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Mass Fraction ◽  
High Performance ◽  
Phenolic Resin ◽  
Strong Dependence ◽  
Coal Tar ◽  
Carbon Foam ◽  
Coal Tar Pitch ◽  
Thermal Conductivity Λ

A novel high-performance carbon foam (CF) was fabricated through the addition of phenolic resin (PR) into a coal tar pitch (CTP) based precursor. The effects of mass fraction of a PR additive on the crystalline structures, morphologies, compressive strength (σ) and thermal conductivity (λ) of resultant CF material were investigated systematically. Characterization showed a strong dependence of CF’s performance from the composition and optical texture of the precursor, which were mainly depending on the polycondensation and polymerization reactions between PR and raw CTP. Comparing with the strength of pristine CF at 6.5 MPa, the σ of mCF-9 (13.1 MPa) was remarkably enhanced by 100.1%. However, the λ of mCF-9 substantially reduced to 0.9 m−1K−1 compared with 18.2 W m−1K−1 of pristine CF. Thus, this modification strategy to produce microporous CF materials from raw CTP provides a new protocol for the fabrication of high-performance carbon based materials.

Effects of Concentrations of NaCl on the Sintering and Thermal Conductivity of Forsterite

2016 ◽  
Vol 697 ◽  
pp. 437-440 ◽  
Author(s):  
Jun Ding ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng ◽  
Ding Guo ◽  
Heng Shang
Keyword(s):  
Thermal Conductivity ◽  
Liquid Phase ◽  
Diffusion Mechanism ◽  
Salt Content ◽  
Liquid Phase Sintering ◽  
Sintering Process ◽  
Sintering Time ◽  
Two Samples ◽  
Insulation Effect ◽  
Better Than

This paper aims to study the effects of NaCl on the sintering of forsterite as well as the thermal conductivity of the sintering products. In the sintering process, NaCl played a role in the system by mainly providing a liquid phase sintering environment in order to promote grain growth and forsterite sintering. Moreover, the model of liquid phase sintering was established in this paper. In the initial sintering stage, the phenomenon of particle re-arrangement was not significant, and dissolution-precipitation was regarded as the dominant sintering mechanism. With the extension of the sintering time, the middle and later stages of the sintering process were mainly controlled by the diffusion mechanism. A test of the thermal conductivity of samples with 40% and 50% NaCl was carried out, which indicated that the thermal conductivity of the two samples ranged from 0.3 to 0.4 W·m-1·k-1. At the same temperatures, the thermal conductivity of the sample with a salt content of 50% was lower than that of the sample with a salt concentration of 40%. Also, the heat insulation effect of the sample with a salt content of 50% was better than that of the sample of 40% . Hence, it can be concluded that the higher the salt content in the sample, the lower the thermal conductivity of the sample.

scholarly journals Microwave Sintering and Microwave Dielectric Properties of (1–x)Ca0.61La0.26TiO3-xNd(Mg0.5Ti0.5)O3 Ceramics

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 438
Author(s):  
Shuwei Yang ◽  
Bingliang Liang ◽  
Changhong Liu ◽  
Jin Liu ◽  
Caisheng Fang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Mobile Communications ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Microwave Dielectric Properties ◽  
Conventional Heating ◽  
Sintering Process ◽  
Microwave Dielectric ◽  
Sintering Time ◽  
Frequency Temperature

The (1–x)Ca0.61La0.26TiO3-xNd(Mg0.5Ti0.5)O3 [(1–x)CLT-xNMT, x = 0.35~0.60] ceramics were prepared via microwave sintering. The effects of sintering temperature and composition on the phase formation, microstructure, and microwave dielectric properties were investigated. The results show that the microwave sintering process requires a lower sintering temperature and shorter sintering time of (1–x)CLT-xNMT ceramics than conventional heating methods. All of the (1–x)CLT-xNMT ceramics possess a single perovskite structure. With the increase of x, the dielectric constant (ε) shows a downward trend; the quality factor (Qf) drops first and then rises significantly; the resonance frequency temperature coefficient (τf) keeps decreasing. With excellent microwave dielectric properties (ε = 51.3, Qf = 13,852 GHz, τf = −1.9 × 10−6/°C), the 0.65CLT-0.35NMT ceramic can be applied to the field of mobile communications.

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

Investigation on thermal conductivity and mechanical properties of Si3N4 ceramics via one-step sintering

2021 ◽  
Author(s):  
Chaochao Ye ◽  
Yongsheng Liu ◽  
Changchun Wang ◽  
Wenqing Wei ◽  
Hongsheng Jia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
One Step ◽  
Si3n4 Ceramics

One-Step Multilevel Microfabrication by Reaction−Diffusion

Langmuir ◽  
2005 ◽  
Vol 21 (1) ◽  
pp. 418-423 ◽  
Author(s):  
Christopher J. Campbell ◽  
Rafal Klajn ◽  
Marcin Fialkowski ◽  
Bartosz A. Grzybowski
Keyword(s):  
Reaction Diffusion ◽  
One Step

Clathrate and other solid phases in the tetrahydrofuran–water system: thermal conductivity and heat capacity under pressure

1982 ◽  
Vol 60 (7) ◽  
pp. 881-892 ◽  
Author(s):  
Russell G. Ross ◽  
Per Andersson
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Water System ◽  
Clathrate Hydrate ◽  
Transient Hot Wire ◽  
Guest Molecules ◽  
Hydrate Phase ◽  
Wire Method ◽  
Solid Phases ◽  
Thermal Conductivity Λ

Solid phases in the tetrahydrofuran–water (THF–H2O) system were investigated in the temperature range 100–260 K and at pressures up to 1.5 GPa. Thermal conductivity, λ, and heat capacity per unit volume, ρcp, were measured, using the transient hot-wire method. We made measurements on solid phases having nominal compositions THF•17H2O, THF•7•1H2O, and THF•4•6H2O, which we refer to as phases α, β, and γ, respectively. Phase α is known to be a structure II clathrate hydrate, and λ for this phase was found to be similar to other crystalline solids which are glass-like in relation to their thermal properties. Low-energy excitations are known to be relevant to the properties of glass-like solids, and, in the case of phase α, were probably rotational vibrations of the THF guest molecules. Phase β was similar, and we inferred that it was probably a structure I clathrate hydrate. Phase γ behaved nearly like a normal crystal phase at low temperatures, but λ became almost independent of temperature near melting. At 1.1 GPa and 130 K, we found evidence that phase α transformed, on pressurization, to a metastable modification which may be a new high-density form of clathrate hydrate. The astrophysical implications of our results were mentioned briefly.

scholarly journals Influence of prolonged sintering time on density and electrical properties of isothermally sintered cordierite-based ceramics

2013 ◽  
Vol 45 (2) ◽  
pp. 157-164 ◽  
Author(s):  
A. Peles ◽  
N. Djordjevic ◽  
N. Obradovic ◽  
N. Tadic ◽  
V.B. Pavlovic
Keyword(s):  
Electrical Properties ◽  
Mechanical Activation ◽  
Compaction Pressure ◽  
High Energy ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Air Atmosphere ◽  
Atomic Force ◽  
Sintering Time ◽  
High Energy Ball Mill

Mechanical activation is a commonly used and relatively fast and inexpensive procedure for sample preparation before the sintering process. Cordierite, a stoichiometric mixture of three different oxides (2MgO?2Al2O3?5SiO2) is a very attractive, widely used high-temperature ceramic material. The mechanical activation of the starting mixtures with 5.00 mass% TiO2 was performed in a high energy ball mill during 10-80 min. The applied compaction pressure before the sintering process was 2t/cm2, based on our recent investigation. The sintering process was performed at 1350oC for 2h and 4h in air atmosphere. X-ray diffraction was used to analyze the phase composition of non-activated and 80 min activated samples, sintered for 2 and 4h, respectively. Scanning electron microscopy was performed to analyze the microstructure of both compacted and sintered samples. Atomic force microscope was used to investigate the surface of the sintered samples. This paper investigates the influence of prolonged sintering time on the densities of the sintered samples, along with electrical properties.

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