Improving the high temperature tribology of polyimide by molecular structure design and grafting POSS

2021 ◽  
Author(s):  
Yuhang Yin ◽  
Jingfu Song ◽  
Gai Zhao ◽  
Qingjun Ding
Keyword(s):  
Molecular Structure ◽  
High Temperature ◽  
Structure Design ◽  
High Temperature Tribology

scholarly journals Simple Algebraic Expressions for the Prediction and Control of High-Temperature Annealed Structures by Linear Perturbation Analysis

2021 ◽  
Vol 26 (2) ◽  
pp. 43
Author(s):  
Constantino Grau Grau Turuelo ◽  
Cornelia Breitkopf
Keyword(s):  
High Temperature ◽  
Surface Diffusion ◽  
Perturbation Analysis ◽  
Algebraic Model ◽  
Structure Design ◽  
Linear Perturbation ◽  
Prediction And Control ◽  
Void Shape ◽  
Void Structure ◽  
And Control

The prediction and control of the transformation of void structures with high-temperature processing is a critical area in many engineering applications. In this work, focused on the void shape evolution of silicon, a novel algebraic model for the calculation of final equilibrium structures from initial void cylindrical trenches, driven by surface diffusion, is introduced. This algebraic model provides a simple and fast way to calculate expressions to predict the final geometrical characteristics, based on linear perturbation analysis. The obtained results are similar to most compared literature data, especially, to those in which a final transformation is reached. Additionally, the model can be applied in any materials affected by the surface diffusion. With such a model, the calculation of void structure design points is greatly simplified not only in the semiconductors field but in other engineering fields where surface diffusion phenomenon is studied.

Recent development of heavy atom-free triplet photosensitizers: molecular structure design, photophysics and application

2021 ◽  
Author(s):  
Xue Zhang ◽  
Zhijia Wang ◽  
Yuqi Hou ◽  
Yuxin Yan ◽  
Jianzhang Zhao ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Heavy Atom ◽  
Structure Design

Triplet photosensitizers (PSs) have attracted much attention in recent years, due to the significance of this kind of compounds in fundamental photochemistry study, as well as of applications in photocatalysis,...

Conceptual Structure Design of High Temperature Isolation Valve for High Temperature Gas Cooled Reactor

2010 ◽  
Author(s):  
Shoji Takada ◽  
Kenji Abe ◽  
Yoshiyuki Inagaki
Keyword(s):  
High Temperature ◽  
Hydrogen Production ◽  
Production System ◽  
Conceptual Structure ◽  
Structure Design ◽  
Radioactive Material ◽  
Normal Operation ◽  
Temperature History ◽  
Allowable Limit ◽  
High Temperature Gas

The high temperature isolation valve (HTIV) is a key component to assure the safety of a high temperature gas cooled reactor (HTGR) connected with a hydrogen production system, that is, protection of radioactive material release from the reactor to the hydrogen production system and combustible gas ingress to the reactor at the accident of fracture of an intermediate heat exchanger and the chemical reactor. The HTIV used in the helium condition over 900 °C, however, has not been made for practical use yet. The conceptual structure design of an angle type HTIV was carried out. A seat made of Hasteloy-XR is welded inside a valve box. Internal thermal insulation is employed around the seat and a liner because high temperature helium gas over 900 °C flows inside the valve. Inner diameter of the top of seat was set 445 mm based on fabrication experiences of valve makers. A draft overall structure was proposed based on the diameter of seat. The numerical analysis was carried out to estimate temperature distribution and stress of metallic components by using a three-dimensional finite element method code. Numerical results showed that the temperature of the seat was simply decreased from the top around 900 °C to the root, and the thermal stress locally increased at the root of the seat which was connected with the valve box. The stress was lowered below the allowable limit 120 MPa by decreasing thickness of the connecting part and increasing the temperature of valve box to around 350 °C. The stress also increased at the top of the seat. Creep analysis was also carried out to estimate a creep-fatigue damage based on the temperature history of the normal operation and the depressurization accident.

An Experimental Study on Insulating Property of Helium in High Temperature Gas Cooled Reactor

2014 ◽  
Author(s):  
Shan Yue ◽  
Xingnan Liu ◽  
Zhengang Shi
Keyword(s):  
High Temperature ◽  
Electrical Equipment ◽  
Structure Design ◽  
Nuclear Industry ◽  
Parallel Plane ◽  
Primary Coolant ◽  
Experimental Platform ◽  
Insulating Properties ◽  
High Temperature Gas ◽  
Better Than

HTGR, short for high temperature gas cooled reactor, has gained a lot of attention in nuclear industry. Gas helium, 7MPa in pressure, is used as primary coolant of HTR-PM in where there are a lot of electrical equipment. Insulating property of helium is worse than that of air according to Paschen curves and there are very few articles or related standards about insulating property of high pressure gas helium, which makes the electrical equipment structure design lack of basis. In this study, an experimental platform for testing insulating performance is designed, based on which the experiments of testing the withstanding voltages of penetration assemblies and the breakdown voltages of parallel plane electrodes at different pressures are carried out. The results show that for both the penetration assemblies and the parallel plane, their breakdown voltages in helium are far lower than in air under the same condition of 15°C /0.1MPa. For the penetration assemblies, their insulating properties in helium at 150°C/7MPa are better than those in air at 15°C/0.1MPa.

scholarly journals Tunable Narrowband Silicon-Based Thermal Emitter with Excellent High-Temperature Stability Fabricated by Lithography-Free Methods

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1814
Author(s):  
Guozhi Hou ◽  
Qingyuan Wang ◽  
Yu Zhu ◽  
Zhangbo Lu ◽  
Jun Xu ◽  
...  
Keyword(s):  
High Temperature ◽  
Absorption Spectra ◽  
Fdtd Method ◽  
Temperature Stability ◽  
High Energy ◽  
Structure Design ◽  
Bragg Reflector ◽  
High Temperature Stability ◽  
Absorption Performance ◽  
Thermal Emitter

Thermal emitters with properties of wavelength-selective and narrowband have been highly sought after for a variety of potential applications due to their high energy efficiency in the mid-infrared spectral range. In this study, we theoretically and experimentally demonstrate the tunable narrowband thermal emitter based on fully planar Si-W-SiN/SiNO multilayer, which is realized by the excitation of Tamm plasmon polaritons between a W layer and a SiN/SiNO-distributed Bragg reflector. In conjunction with electromagnetic simulations by the FDTD method, the optimum structure design of the emitter is implemented by 2.5 periods of DBR structure, and the corresponding emitter exhibits the nearly perfect narrowband absorption performance at the resonance wavelength and suppressed absorption performance in long wave range. Additionally, the narrowband absorption peak is insensitive to polarization mode and has a considerable angular tolerance of incident light. Furthermore, the actual high-quality Si-W-SiN/SiNO emitters are fabricated through lithography-free methods including magnetron sputtering and PECVD technology. The experimental absorption spectra of optimized emitters are found to be in good agreement with the simulated absorption spectra, showing the tunable narrowband absorption with all peak values of over 95%. Remarkably, the fabricated Si-W-SiN/SiNO emitter presents excellent high-temperature stability for several heating/cooling cycles confirmed up to 1200 K in Ar ambient. This easy-to-fabricate and tunable narrowband refractory emitter paves the way for practical designs in various photonic and thermal applications, such as thermophotovoltaic and IR radiative heaters.

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