scholarly journals Thermomechanical properties of mullitic materials

2017 ◽  
Vol 11 (4) ◽  
pp. 322-328 ◽  
Author(s):  
Jan Urbánek ◽  
Jiří Hamácek ◽  
Jan Machácek ◽  
Jaroslav Kutzendörfer ◽  
Jana Hubálková
Keyword(s):  
Flexural Strength ◽  
High Temperatures ◽  
Maximum Level ◽  
Ceramic Materials ◽  
Mechanical Tests ◽  
Thermomechanical Properties ◽  
Refractory Materials

Mechanical tests provide important information about the properties and behaviour of materials. Basic tests include the measurement of flexural strength and in case of refractory materials, the measurement of flexural strength at high temperatures as well. The dependence of flexural strength on the temperature of ceramic materials usually exhibits a constant progression up to a certain temperature, where the material starts to melt and so the curve begins to decline. However, it was discovered that ceramic mullitic material with a 63 wt.% of Al2O3 exhibits a relatively significant maximum level of flexural strength at about 1000?C and refractory mullitic material with a 60 wt.% of Al2O3 also exhibits a similar maximum level at about 1100?C. The mentioned maximum is easily reproducible, but it has no connection with the usual changes in structure of material during heating. The maximum was also identified by another measurement, for example from the progression of the dynamic Young?s modulus or from deflection curves. The aim of this work was to analyse and explain the reason for the flexural strength maximum of mullitic materials at high temperatures.

Mechanical properties and toughening mechanisms of epoxy/graphene nanocomposites

2015 ◽  
Vol 35 (3) ◽  
pp. 257-266 ◽  
Author(s):  
Rahim Eqra ◽  
Kamal Janghorban ◽  
Habib Daneshmanesh
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Flexural Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Graphene Nanosheets ◽  
Flexural Modulus ◽  
Mechanical Tests ◽  
Toughening Mechanism ◽  
Graphene Nanocomposites

Abstract Because of extraordinary physical, chemical and mechanical properties, graphene nanosheets (GNS) are suitable fillers for optimizing the properties of different polymers. In this research, the effect of GNS content (up to 1 wt.%) on tensile and flexural properties, morphology of fracture surface, and toughening mechanism of epoxy were investigated. Results of mechanical tests showed a peak for tensile and flexural strength of samples with 0.1 wt.% GNS such that the tensile and flexural strength improved by 13% and 3.3%, respectively. The Young’s modulus and flexural modulus increased linearly with GNS content, although the behavior of the Young’s modulus was more remarkable. Morphological investigations confirmed this behavior because the GNS dispersion in the epoxy matrix was uniform at lower contents and agglomerated at higher contents. Finally, microscopical observation showed that the major toughening mechanism of graphene-epoxy nanocomposites was crack path deflection, which changed the mirror fracture surface of the pure epoxy to rough surface.

Large-volume cubic press produces high temperatures above 4000 Kelvin for study of the refractory materials at pressures

2020 ◽  
Vol 91 (1) ◽  
pp. 015118 ◽  
Author(s):  
Xuefeng Zhou ◽  
Dejiang Ma ◽  
Lingfei Wang ◽  
Yusheng Zhao ◽  
Shanmin Wang
Keyword(s):  
High Temperatures ◽  
Large Volume ◽  
Refractory Materials

The Quality of Brazed Ceramic and Cemented Carbide Joints - A Mechanical and Metallurgical Assessment

2010 ◽  
Vol 64 ◽  
pp. 108-114 ◽  
Author(s):  
Wolfgang Tillmann ◽  
Lukas Wojarski ◽  
Benjamin Lehmert
Keyword(s):  
Thermal Stresses ◽  
Mechanical Performance ◽  
Ceramic Materials ◽  
Mechanical Tests ◽  
Point Of View ◽  
Cemented Carbides ◽  
Full Potential ◽  
Ceramic Surface ◽  
Reaction Products

The availability of adequate joining technologies is of major importance in order to exploit the full potential of ceramic materials. The same is true for joints between cemented carbides and their counterparts. Such joints are not easy to manufacture due to wetting and bonding problems as well as induced thermal stresses. Currently, active brazing is a potential approach for fabricating such joints. The filler alloy contains reactive agents such as Titanium or Hafnium etc. that interact by forming wettable reaction layers on the ceramic surface. It is self-evident that they function very well on cemented carbides as well. The paper describes potential wetting and bonding reactions from a metallurgical point of view. Ceramics, superabrasive and cemented carbides are investigated with respect to interfacial reactions. The quality of the reaction products is of crucial importance regarding the mechanical performance of the joints, as their immanent brittleness can lead to a significant weakening. Apart from metallurgical assessments, mechanical tests are conducted in order to deliver data for their integration in hybrid structures. FE methods can be applied to assess the stress situation in the final joint. Thus it is possible to adjust the design accordingly.

John Hugh Chesters, O.B.E. 6 October 1906 – 14 December 1994

2000 ◽  
Vol 46 ◽  
pp. 37-48
Author(s):  
G.W. Greenwood
Keyword(s):  
Heat Flow ◽  
Thermal Shock ◽  
High Temperatures ◽  
Refractory Materials ◽  
Steel Melting ◽  
Structure And Properties ◽  
Corrosive Environments ◽  
Efficiency And Reliability

John Hugh Chesters, fulfilling his ambitions as a schoolboy, had a lifelong involvement in the application of science to solve practical and industrially important problems. His major contributions relate mainly to the efficiency and reliability of furnaces for steel melting. These were accomplished through research on refractory materials for furnace linings and on heat flow. His work led to great improvements in the processing and use of ceramics in bulk and in the characterization of the structure and properties of these materials. As a result, the capability of appropriate refractory materials to withstand stresses, sudden thermal shock, and corrosive environments for the long periods at high temperatures that arise in iron and steelmaking processes was substantially increased.

Verrucarin A and roridin E produced on rocket by Myrothecium roridum under different temperatures and CO2 levels

2017 ◽  
Vol 10 (3) ◽  
pp. 229-236 ◽  
Author(s):  
P. Bosio ◽  
I. Siciliano ◽  
G. Gilardi ◽  
M.L. Gullino ◽  
A. Garibaldi
Keyword(s):  
Disease Severity ◽  
High Temperatures ◽  
Maximum Level ◽  
Temperature Influence ◽  
Eruca Sativa ◽  
Mycotoxin Production ◽  
Co2 Levels ◽  
The Future ◽  
Different Temperatures ◽  
Myrothecium Roridum

The behaviour of Myrothecium roridum, artificially inoculated on cultivated rocket (Eruca sativa), has been evaluated under eight different temperature and CO2 concentration combinations (from 14-18 °C to 26-30 °C and with 400-450 or 800-850 ppm of CO2). The pathogen isolate used for this study was inoculated on rocket and disease severity increased with high temperatures for both CO2 levels. Verrucarin A and roridin E mycotoxins were produced under all the tested temperatures at high CO2 conditions. The maximum level of verrucarin A was found at 14-18 °C and 800-850 ppm of CO2, and the maximum roridin E production was detected at 26-30 °C with 800-850 ppm of CO2. The results obtained in this study show that both the CO2 concentration and the temperature influence disease severity and mycotoxin production in different ways. An increase in temperature, which is favourable for attacks of the pathogen, could induce the spread of M. roridum in temperate regions, and this pathogen could take on even greater importance in the future, considering its ability to produce mycotoxins.

Sign in / Sign up

Export Citation Format

Share Document