Reduced thermal resistance of the silicon-synthetic diamond composite substrates at elevated temperatures

2010 ◽  
Vol 97 (3) ◽  
pp. 031904 ◽  
Author(s):  
V. Goyal ◽  
S. Subrina ◽  
D. L. Nika ◽  
A. A. Balandin
Keyword(s):  
Thermal Resistance ◽  
Elevated Temperatures ◽  
Synthetic Diamond ◽  
Diamond Composite ◽  
Composite Substrates

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

Phonon conduction in GaN-diamond composite substrates

2017 ◽  
Vol 121 (5) ◽  
pp. 055105 ◽  
Author(s):  
Jungwan Cho ◽  
Daniel Francis ◽  
David H. Altman ◽  
Mehdi Asheghi ◽  
Kenneth E. Goodson
Keyword(s):  
Diamond Composite ◽  
Phonon Conduction ◽  
Composite Substrates

scholarly journals Water activity change at elevated temperatures and thermal resistance of Salmonella in all purpose wheat flour and peanut butter

2016 ◽  
Vol 81 ◽  
pp. 163-170 ◽  
Author(s):  
Roopesh M. Syamaladevi ◽  
Ravi Kiran Tadapaneni ◽  
Jie Xu ◽  
Rossana Villa-Rojas ◽  
Juming Tang ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Water Activity ◽  
Wheat Flour ◽  
Elevated Temperatures ◽  
Peanut Butter ◽  
Activity Change

scholarly journals Thermal analysis of postcured aramid fiber/epoxy composites

2021 ◽  
Vol 60 (1) ◽  
pp. 479-489
Author(s):  
Konstantinos Karvanis ◽  
Soňa Rusnáková ◽  
Ondřej Krejčí ◽  
Alena Kalendová
Keyword(s):  
Thermal Resistance ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Thermomechanical Analysis ◽  
Mechanical Analysis ◽  
Aramid Fiber ◽  
Point Of View ◽  
Creep Recovery ◽  
Aramid Fibers ◽  
Scanning Calorimetry

Abstract In this study, aramid fiber-reinforced polymer (AFRP) composites were prepared and then postcured under specific heating/cooling rates. By dynamic mechanical analysis, the viscoelastic properties of the AFRP composites at elevated temperatures and under various frequencies were determined. Thermomechanical analysis (TMA), in the modes of creep-recovery and stress–relaxation tests, was also performed. Furthermore, differential scanning calorimetry was also used, and the decomposition of the AFRP composites, aramid fibers, and pure postcured epoxy, in two different atmospheres, namely, air atmosphere and nitrogen (N2) atmosphere, was explored by the thermogravimetric analysis (TGA). From this point of view, the aramid fibers showed remarkably thermal resistance, in N2 atmosphere, and the volume fraction of fibers (Φf) was calculated to be Φf = 51%. In the TGA experiments, the postcured AFRP composites showed very good thermal resistance, both in air and N2 atmosphere, and this characteristic in conjunction with their relatively high T g, which is in the range of 85–95°C, depending on the frequency and the determination method, classifies these composites as potential materials in applications where the resistance in high temperatures is a required characteristic.

scholarly journals Experimental Study of Surface Etching in Synthetic Diamond Microcrystals due to Presence of Cu and Fe at High Pressure

2020 ◽  
pp. 18-21
Author(s):  
I.A. Ishutin ◽  
A.A. Chepurov ◽  
E.I. Zhimulev
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Synthetic Diamond ◽  
Close Contact ◽  
High Pressure Cell ◽  
Diamond Composite ◽  
Refractory Oxides ◽  
Diamond Crystals ◽  
Composite Diamond ◽  
High Pressure Apparatus

In the present work, microcrystals of synthetic diamond extracted from a metal-diamond composite were investigated. A composite based on Cu and Fe was obtained by sintering at a pressure of 4 GPa and a temperature of1300 °C. The experiments were carried out using a split-sphere high-pressure apparatus BARS. The high-pressure cell was made of refractory oxides ZrO2, CaO, and MgO using a tubular graphite heater. In the composite, diamond grains were in close contact with neighboring diamonds, and the metal phase filled the interstices. The study of the diamond crystals demonstrated the appearance of newly formed micromorphological structures on the surfaces in the form of numerous cavities of irregular shape on the faces of octahedron, as well as pyramids on the faces of cube, the morphological elements of which follow the contours of the cube face of the diamond. Thus, the results of the work evidence for the processes of etching of the diamond crystals during the experiments, which is associated with the presence of metallic iron in the composite. This type of etching forms a roughly cavernous surface on the diamond crystals, which can be considered as an additional factor for improving the metal-diamond bond in copper-based composites.

Thermal Resistance of Listeria monocytogenes, Salmonella Heidelberg, and Escherichia coli O157:H7 at Elevated Temperatures†

2004 ◽  
Vol 67 (8) ◽  
pp. 1666-1670 ◽  
Author(s):  
LIHAN HUANG
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Continuous Flow ◽  
Elevated Temperatures ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Flow Apparatus ◽  
D Values ◽  
Salmonella Heidelberg

A continuous-flow apparatus was developed to measure thermal resistance (D- and z-values) of microorganisms at temperatures above 65°C. This apparatus was designed to test whether vegetative microorganisms exhibited unusually high thermal resistance that prevented them from being completely eliminated at temperatures applicable to vacuum-steam-vacuum processes (116 to 157°C). The apparatus was composed of a high-pressure liquid chromatography pump, a heating unit, and a cooling unit. It was designed to measure small D-values (<1 s). Three randomly selected organisms, Listeria monocytogenes, Salmonella Heidelberg, and Escherichia coli O157:H7 suspended in deionized water were tested in the continuous-flow apparatus at temperatures ranging from 60 to 80°C. Studies showed that the D-values of these organisms ranged from 0.05 to 20 s. Heating at 80°C was found to be basically the physical limit of the system. Experimental results showed that L. monocytogenes, Salmonella Heidelberg, and E. coli O157:H7 did not exhibit unusual heat resistance. The conditions used in the vacuum-steam-vacuum processes should have completely inactivated organisms such as L. monocytogenes, Salmonella Heidelberg, and E. coli O157:H7 if present on food surfaces. The complete destruction of bacteria during vacuum-steam-vacuum processes might not occur because the surface temperatures never reached those of the steam temperatures and because bacteria might be hidden beneath the surface and was thus never exposed to the destructive effects of the steam.

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