scholarly journals Microwave Heating Behavior in SiC Fiber-MO2 Mixtures (M = Ce, Zr)—Selective Heating of Micrometer-Sized Fibers Facilitated by ZrO2 Powder

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 47 ◽  
Author(s):  
Keiichiro Kashimura ◽  
Jun Fukushima ◽  
Tomoaki Namioka ◽  
Takashi Fujii ◽  
Hirotsugu Takizawa ◽  
...  
Keyword(s):  
High Temperature ◽  
Hot Spots ◽  
Weight Ratio ◽  
Temperature Gradients ◽  
Maximum Temperature ◽  
Selective Heating ◽  
Sic Fiber ◽  
Maximum Value ◽  
Rate Maximum ◽  
Heating Behavior

SiC fiber-MO2 (M = Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters continued to increase as the weight ratio of the SiC fiber increased; in contrast, for the SiC fiber-ZrO2 mixture, these parameters reached a maximum value at a certain composition. A thermal gradient of 500 °C was observed at a microlevel in the SiC fiber-ZrO2 mixture, and hot spots were located in regions with a certain composition. This result not only contributes to designing a novel good microwave absorber but also presents new aspects with regard to high-temperature microwave processing, including the mechanism behind the high-temperature gradients on the order of micrometers as well as engineering applications that utilize these high-temperature gradients.

Experimental Investigation on the Minichannel Cold Plate for High Temperature Uniformity Based on a Compact Thermal Model

2013 ◽  
Author(s):  
Xiaobing Luo ◽  
Zhangming Mao
Keyword(s):  
High Temperature ◽  
Working Conditions ◽  
Thermal Model ◽  
Maximum Temperature ◽  
Large Temperature ◽  
Heat Sources ◽  
Cold Plate ◽  
Temperature Uniformity ◽  
Maximum Temperature Difference ◽  
Maximum Value

A compact thermal model for multiple heat sources mounted on minichannel cold plate to achieve high temperature uniformity was presented in the authors’ previous work. In this paper, based on this compact thermal model, a fractal tree-like minichannel cold plate was designed and fabricated to obtain high temperature uniformity, and its thermal performance was tested under different working conditions by experiments. The comparison reveals that the measured temperatures are close to the ones predicted by the compact thermal model. The cold plate designed based on the compact thermal model can help multiple heat sources achieve high temperature uniformity, and the maximum temperature difference among the heat sources is 1.3 °C. Moreover, a straight minichannel cold plate was designed and tested under the same conditions. The measured results show that there exists relatively large temperature gap among the heat sources, and the maximum value is 6.7°C, which is much higher than 1.3 °C in the fractal tree-like minichannel. Therefore, the fractal tree-like microchannel or minichannel cold plate has an advantage over the straight one in obtaining temperature uniformity for multiple heat sources.

scholarly journals A Study of Films Incorporating Magnetite Nanoparticles as Susceptors for Induction Welding of Carbon Fiber Reinforced Thermoplastic

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 318 ◽  
Author(s):  
Inseok Baek ◽  
Seoksoon Lee
Keyword(s):  
Carbon Fiber ◽  
Induction Heating ◽  
Weight Ratio ◽  
Thermoplastic Composites ◽  
Maximum Temperature ◽  
Thermoplastic Resin ◽  
Metal Mesh ◽  
Manufacturing Method ◽  
Lap Shear ◽  
Heating Behavior

Induction welding is a fast, clean, noncontact process that often uses a metal-mesh susceptor to facilitate localized controlled heating; however, the metal mesh presents various problems. In this study, the induction heating behavior of a 450 μ m thick thin-film susceptor, fabricated by mixing magnetite (Fe 3 O 4 ) nanoparticles (NPs) and PA6/carbon fiber (CF) (30%) thermoplastic resin, was examined with respect to the weight ratio of Fe 3 O 4 (50, 67, 75, and 80 wt%). The useful induction heating behavior of the 75 wt% Fe 3 O 4 susceptor suggested its suitability for additional heat treatment experiments, carried out at 3.4 kW at a frequency of 100 kHz. This susceptor attained the same maximum temperature during 10 cycles of repeated induction heating and cooling. It was then used to weld two thermoplastic composites, with 60 s of induction heating followed by 120 s of simultaneous cooling and pressing. The resulting welded joints had lap shear strength values of 36.8, 34.0, and 36.4 MPa under tensile test loads of 884, 817, and 874 N, respectively. Scanning electron microscopy images confirmed a uniform weld quality. Thus, the proposed manufacturing method, involving the incorporation of Fe 3 O 4 NPs into thermoplastic resin, should help expand the range of applications for thermoplastic composites.

Precipitate coarsening during hot-compression testing of NiAl + 2 at.% Nb

1986 ◽  
Vol 44 ◽  
pp. 598-599
Author(s):  
W. M. Sherman ◽  
K. M. Vedula
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Weight Ratio ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Testing ◽  
Second Phase ◽  
Precipitate Coarsening ◽  
High Temperature Mechanical Properties ◽  
Ordered Intermetallic

The strength to weight ratio and oxidation resistance of NiAl make this ordered intermetallic, with some modifications, an attractive candidate to compete with many superalloys for high temperature applications. Recent studies have shown that the inherent brittleness of many polycrystalline intermetallics can be overcome by micro and macroalloying. It has also been found that the high temperature mechanical properties of NiAl can be enhanced through the addition of Nb by powder metallurgical techniques forming a dispersed second phase through interdiffusion in a polycrystalline matrix. A drop in the flow stress is observed however in a NiAl-2 at.% Nb alloy after 0.2 % strain during constant strain rate hot compression testing at 1025°C. The object of this investigation was to identify the second phase and to determine the cause of the flow stress drop.

G-E ALLOY J-1300

Alloy Digest ◽  
1959 ◽  
Vol 8 (1) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Precipitation Hardening ◽  
Base Alloy ◽  
Weight Ratio ◽  
Heat Treating ◽  
General Electric Company ◽  
Iron Base Alloy ◽  
Electric Company ◽  
Temperature Performance

Abstract G-E ALLOY J-1300 is a precipitation hardening iron-base alloy with an excellent strength to weight ratio. It is recommended for applications in the 1350 F. range. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: SS-83. Producer or source: General Electric Company.

scholarly journals Study on the Stability of the Electrical Connection of High-Temperature Pressure Sensor Based on the Piezoresistive Effect of P-Type SiC

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 216
Author(s):  
Yongwei Li ◽  
Ting Liang ◽  
Cheng Lei ◽  
Qiang Li ◽  
Zhiqiang Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Sensor ◽  
Pressure Sensors ◽  
Extreme Environment ◽  
Maximum Temperature ◽  
Piezoresistive Effect ◽  
Electrical Connection ◽  
Contact Stability ◽  
The Stability ◽  
P Type

In this study, a preparation method for the high-temperature pressure sensor based on the piezoresistive effect of p-type SiC is presented. The varistor with a positive trapezoidal shape was designed and etched innovatively to improve the contact stability between the metal and SiC varistor. Additionally, the excellent ohmic contact was formed by annealing at 950 °C between Ni/Al/Ni/Au and p-type SiC with a doping concentration of 1018cm−3. The aging sensor was tested for varistors in the air of 25 °C–600 °C. The resistance value of the varistors initially decreased and then increased with the increase of temperature and reached the minimum at ~450 °C. It could be calculated that the varistors at ~100 °C exhibited the maximum temperature coefficient of resistance (TCR) of ~−0.35%/°C. The above results indicated that the sensor had a stable electrical connection in the air environment of ≤600 °C. Finally, the encapsulated sensor was subjected to pressure/depressure tests at room temperature. The test results revealed that the sensor output sensitivity was approximately 1.09 mV/V/bar, which is better than other SiC pressure sensors. This study has a great significance for the test of mechanical parameters under the extreme environment of 600 °C.

Study on the Thermo-Hydrodynamic of a Dry Gas Seal in Helium Circulator for High Temperature Gas-Cooled Reactor

2011 ◽  
Author(s):  
Jianshu Lin ◽  
Hong Wang
Keyword(s):  
High Temperature ◽  
Film Flow ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Analysis Method ◽  
Dry Gas Seal ◽  
Safety Requirements ◽  
Simulation Results ◽  
Gas Seals ◽  
High Temperature Gas

A comprehensive analysis method is proposed to resolve the problem of simulating a complex thermo-flow with two kinds of distinct characteristic length in the dry gas seal, and a conjugated simulation of the complicated heat transfer and the gas film flow is carried out by using the commercial CFD software CFX. By using the proposed method, a three dimensional of velocity and pressure field in the gas film flow and the temperature distribution within the sealing rings are investigated for three kinds of film thickness, respectively. A comparison of thermo-hydrodynamics of the dry gas seals is conducted between the sealed gas of air and helium. The latter one is used in a helium circulator for High Temperature Gas-cooled Reactor (HTGR). From comparisons and discussions of a series of simulation results, it will be found that the comprehensive proposal is effective and simulation results are reasonable, and the maximum temperature rise in the dry gas seal is within the acceptable range of HTGR safety requirements.

Shock initiation of explosives: High temperature hot spots explained

2017 ◽  
Vol 111 (6) ◽  
pp. 061902 ◽  
Author(s):  
Will P. Bassett ◽  
Belinda P. Johnson ◽  
Nitin K. Neelakantan ◽  
Kenneth S. Suslick ◽  
Dana D. Dlott
Keyword(s):  
High Temperature ◽  
Hot Spots ◽  
Shock Initiation

scholarly journals OPTIMIZATION OF INORGANIC COMPONENTS OF FIRE PROTECTIVE VARNISH FOR WOOD

2021 ◽  
pp. 123-132
Author(s):  
Yu. Tsapko ◽  
◽  
А. Tsapko ◽  
O. Bondarenko ◽  
V. Lomaha ◽  
...  
Keyword(s):  
High Temperature ◽  
Fire Retardant ◽  
Protective Layer ◽  
Combustion Products ◽  
Wood Products ◽  
Maximum Temperature ◽  
Protective Film ◽  
Insulating Layer ◽  
Combustible Gases ◽  
Material Studies

Abstract. The processes of creation of fire-retardant varnish for wood consisting of a mixture of inorganic and polymeric substances are investigated in the work. It is established that the optimization of the inorganic component leads to a directional ratio of mineral acids and urea capable of effective fire protection of the material. Studies have shown that at the initial temperature of gaseous combustion products T = 68 °C, when exposed to the radiation panel, the untreated sample ignited after 146 s, the flame spread over the entire surface, instead, the sample fire-protected varnish did not ignite, the maximum temperature was 105 °C. In this case, as evidenced by the results of heat resistance, there is a change in the structure of the protective film of the coating. The thickness of the protective layer increases due to the decomposition of the composition, which leads to inhibition of oxidation in the gas and condensed phase, change the direction of decomposition towards the formation of non-combustible gases and combustible coke residue, reduce material combustion and increase flammability index. The coating under the influence of high temperature promotes the formation of a heat-insulating layer of coke, which prevents burning and the passage of high temperature to the material, which is confirmed by the absence of the process of ignition of fire-retardant wood. Features of braking of process of ignition and distribution of a flame of the wood processed by a varnish which consist in several aspects are established. This is the formation of a heat-insulating layer of coke, which prevents burning and the passage of high temperatures to the material, which is confirmed by the absence of the process of ignition of fire-retardant reeds. This indicates the possibility of targeted control of high temperature transfer processes to organic material through the use of special coatings for wood products.

scholarly journals OVEN OR FIREPLACE? (EXPERIMENTAL FIRINGS OF THE VESSELS)

2015 ◽  
Vol 4 (3) ◽  
pp. 37-55
Author(s):  
Yelena Vitalievna Volkova
Keyword(s):  
High Temperature ◽  
Basic Knowledge ◽  
Maximum Temperature ◽  
Firing Process ◽  
Cow Dung ◽  
Natural Clay ◽  
Analytical Studies

The paper contains the results of the field experimental firings in fireplaces and in ovens made on the basis of Samara pottery experimental expedition (Dr N.P. Salugina is the leader of the expedition) in 2013. The author put forward two goals: one is to discover the basic knowledge on firing process with various kinds of fuel, and second is to find out the specific features to discern the vessels fired in fireplaces from the vessels fired in ovens. 20 vessels were prepared to the experiment. The first 10 pots were made of natural clay and the second 10 vessels were made of pottery paste (clay + grog + cow dung). Five simultaneous firings with various kinds of fuel were organized in fireplace and in oven. The author describes in detail the program, main steps, and maximum temperature of firings, the photos of the vessels, and the results of their analytical studies. After the experiments the author came to the next conclusions: firstly - there are absent the reliable features to distinguish the vessels fired in fireplace and in oven, secondly - there is one dependence between a kind pottery paste and a color of fired vessels and another relation between pottery paste and a degree of high-temperature baking of vessels.

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