scholarly journals Brittle Materials in Mechanical Extremes

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4610
Author(s):  
Giovanni Bruno
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
High Temperatures ◽  
3D Imaging ◽  
Construction Materials ◽  
Brittle Materials ◽  
Structural Ceramics ◽  
Special Issue ◽  
The Road ◽  
Very High

The goal of the Special Issue “Brittle Materials in Mechanical Extremes” was to spark a discussion of the analogies and the differences between different brittle materials, such as, for instance, ceramics and concrete. Indeed, the contributions to the Issue spanned from construction materials (asphalt and concrete) to structural ceramics, reaching as far as ice. The data shown in the issue were obtained by advanced microstructural techniques (microscopy, 3D imaging, etc.) and linked to mechanical properties (and their changes as a function of aging, composition, etc.). The description of the mechanical behavior of brittle materials under operational loads, for instance, concrete and ceramics under very high temperatures, offered an unconventional viewpoint on the behavior of brittle materials. This is not at all exhaustive, but a way to pave the road for intriguing and enriching comparisons.

Mechanical properties of advanced SiC fiber composites irradiated at very high temperatures

2011 ◽  
Vol 417 (1-3) ◽  
pp. 416-420 ◽  
Author(s):  
Yutai Katoh ◽  
Kazumi Ozawa ◽  
Tatsuya Hinoki ◽  
Yongbum Choi ◽  
Lance L. Snead ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperatures ◽  
Fiber Composites ◽  
Sic Fiber ◽  
Very High

An Experimental Study on Brazing of Diamonds onto Thin Steel Wires

2010 ◽  
Vol 443 ◽  
pp. 537-542 ◽  
Author(s):  
Guo Qing Zhang ◽  
Hui Huang ◽  
Xi Peng Xu
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Experimental Investigation ◽  
Cross Section ◽  
High Temperatures ◽  
Brittle Materials ◽  
The Body ◽  
Natural Stone ◽  
Steel Wires ◽  
Thin Steel

An experimental investigation was carried out to braze diamond abrasives onto thin steel wires, in which case the brazing was conducted in the vacuum and under high temperatures by using a nickel-based powder as brazing alloy. The morphologies and microstructures of the brazed wires were observed and the comprehensive mechanical properties of the brazed wires were tested. The brazed wires were also used to cut such brittle materials as ceramics, glass, and natural stone. It is shown that a typical phenomenon of brazing alloy’s climbing around the diamond grains was observed in brazing the wires. Through observing the cross-section of brazed wires, it is observed that there is a good bonding between the brazing alloy and the body of steel wires. The crystal grains of the steel wires grew significantly after brazing. Through observing the morphologies of the diamond wires and the surfaces of four workpiece materials, few diamond pull-outs were found on the wires and the kerfs on the workpiece materials were basically flat.

Investigation of the Effects of High Temperature Aging on the Mechanical Behavior of Lead Free Solders

2018 ◽  
Author(s):  
Mohammad S. Alam ◽  
K. M. Rafidh Hassan ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Mechanical Behavior ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Lead Free ◽  
Specimen Preparation ◽  
Stress Strain ◽  
Initial Modulus ◽  
Lead Free Solders

Lead free solders are renowned as interconnects in electronic packaging due to their relatively high melting point, attractive mechanical properties, thermal cycling reliability, and environment friendly chemical properties. The mechanical behavior of lead free solders is highly dependent on the operating temperature. Previous investigations on mechanical characterization of lead free solders have mainly emphasized stress-strain and creep testing at temperatures up to 125 °C. However, electronic devices, sometimes, experience harsh environment applications including well drilling, geothermal energy, automotive power electronics, and aerospace engines where solders are exposed to very high temperatures from 125–200 °C. Mechanical properties of lead free solders at elevated temperatures are limited. In this work, we have investigated the mechanical behavior SAC305 (96.5Sn-3.0Ag-0.5Cu) and SAC_Q (SAC+Bi) lead free solders at extreme high temperatures up to 200 °C. Stress-strain tests were performed on reflowed uniaxial specimens at four elevated temperatures (T = 125, 150, 175, and 200 °C). In addition, changes of the mechanical behavior of these alloys due to isothermal aging at T = 125 °C have been studied. Extreme care has been taken during specimen preparation so that the fabricated solder uniaxial test specimens accurately reflect the solder material microstructures present in actual lead free solder joints. High temperature tensile properties of the solders including initial modulus, yield stress, and ultimate tensile strength have been compared. As expected, our results show substantial degradations of the mechanical properties of lead-free solders at higher temperatures. With prior aging, these degradations become even more significant. Comparison of the results has shown that the addition of Bi to traditional SAC alloys improves their high temperature properties and significantly reduces their aging induced degradations.

Changes of Mechanical Properties of Lightweight Cement Mortar Mixed with Recycled Expanded Polystyrene and Subjected to High Temperatures

2014 ◽  
Vol 1051 ◽  
pp. 752-756 ◽  
Author(s):  
Rocío Sancho ◽  
Ángel Castillo ◽  
Ma Eugenia Maciá ◽  
Rosa Corral
Keyword(s):  
Mechanical Properties ◽  
High Temperatures ◽  
Mechanical Response ◽  
Cement Mortar ◽  
Construction Materials ◽  
Lightweight Aggregate ◽  
Expanded Polystyrene ◽  
Partial Replacement ◽  
Different Temperatures ◽  
Residual Product

The main aim of this paper is to evaluate the influence of the recycled expanded polystyrene as lightweight aggregate on the mechanical properties of lightweight cement mortar when subjected to high temperatures.Various tests have been carried out on different mixtures of mortar. The water/cement mix proportion has always been the same and only the nature of the aggregates has changed, with a partial replacement of the conventional aggregate by recycled ground EPS (EPS-G) with values ranging from 10% to 30%, achieving significant results in relation to exposure to high temperatures. In this research, the samples have been subjected to different temperatures of exposure, in order to analyze the influence of the lightweight recycled arid dosage in the mechanical properties of mortars.The results of this study show the ability of mechanical response at high temperatures with light mortars EPS-G. This study shows how this new mix can be used in different building types, optimizing construction materials and reducing mortars density while transforming a residual product into an active product.

Assessment of the Dynamic Temperature Profile in Fire Loaded Sandwich Structures Based on Wood in Comparison with Conventional Structural Systems

2019 ◽  
Vol 887 ◽  
pp. 98-105
Author(s):  
Marie Rusinová ◽  
Miloš Kalousek ◽  
Jiří Šlanhof
Keyword(s):  
High Temperatures ◽  
Sandwich Structures ◽  
Construction Materials ◽  
Structural Systems ◽  
Internal Environment ◽  
Time Intervals ◽  
Load Bearing ◽  
Low Weight ◽  
In Fire ◽  
Very High

Fire safety is an important feature of healthy internal environment. If a fire breaks out, the interior of fire compartments within the building is exposed to very high temperatures and further phenomena accompanying the burning process. All of them impact the boundaries of the compartment structures, including the structures that are located inside them. Some structures serve the load bearing function hand in hand with fire barriers, some are only fire barriers. As to the dramatic increase of temperature, its impact upon the opposite surface of the fire separating structure should be considered, in particular regarding the behavior of the load bearing elements and their stability. This is topical at the present day, since the conventional construction materials are seen to give way to wooden sandwich structures that are preferred especially for their thermal insulation properties, low weight, small thickness and speediness of construction. The article uses dynamic simulation to illustrate how these modern structures react to high temperatures within specific time intervals, offering comparisons with traditional brick structures.

Sialon Ceramics Sintered with Yttria and Rare Earth Oxides

1992 ◽  
Vol 287 ◽  
Author(s):  
Thommy EkstrÖm
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
High Temperatures ◽  
Large Scale ◽  
Low Cost ◽  
Rare Earth Oxides ◽  
Boundary Phase ◽  
Scale Production ◽  
Large Scale Production ◽  
Very High

ABSTRACTDense single-phase α-, β- and O′-sialon cermics or mixed sialon ceramics without a glassy grain-boundary phase can be prepared at high temperatures and pressures, and these materials are well suited for high-temperature use, but they are usually brittle. Additional quantities of oxides of group IIIB metals in the periodic table are often added as sintering aids to achieve pressureless sintering and thereby to allow more complicated shapes to be manufactured directly and at lower costs. The most common additive is yttria, but the rare earth oxides are also of interest. All these oxides will promote the growth of elongated β crystals in the microstructure, and the fracture toughness will be improved considerably. Low-cost oxides like Nd2O3, La2O3 or CeO2 may replace Y2O3 without significantly impairing the mechanical properties at room temperature. The expensive rare-earth oxides like Sm2O3, Dy2O3 or Yb2O3 have been found to be as good additives as yttria, or even better, but improvements in mechanical properties are generally small and do not justify the use of these additives in large-scale production. The residual intergranular glassy phase usually found in the microstructure of metal-oxide-doped sialons will deteriorate the properties at very high temperatures, and this type of material is best suited for use at operation temperatures below 900-1000°C.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

MODELISATION DE L'INFLUENCE DU TRAITEMENT THERMIQUE SUR LES PROPRIETES MECANIQUES DES ALLIAGES ALUMINIUM-CUIVRE (Al-Cu)

2015 ◽  
Vol 10 (2) ◽  
pp. 2753-2761
Author(s):  
Saad El Madani ◽  
S. ELHAMZI ◽  
A. IBNLFASSI ◽  
L. ZERROUK ◽  
O. BEN LENDA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Solidification Process ◽  
Traitement Thermique ◽  
Homogenization Process ◽  
Fundamental Reason ◽  
Segregation Phenomenon ◽  
Proprietes Mecaniques ◽  
Cooling Velocity ◽  
Copper Effect

In order to master and improve the quality and properties of the final products, the major industrial challenge lies in the possibility of controlling the morphology, size of microstructures that reside within the molded pieces, as well as their defects; this is the fundamental reason according to which we are more and more interested in mastering the growth and germination of such alloys, as well as the developing structures, at the time of solidification process. The modeling reveals as a valuable aid in the mastery of the formation of such heterogeneousness: segregation cells that are incompatible with industrial requirements.   The whole work focuses upon the modeling of the segregation phenomenon of the four hypoeutectic alloys, Al1%Cu, Al2%Cu, Al3%Cu et Al4%Cu, as well as the copper effect upon certain mechanical properties of aluminum. Usually, the microstructure and mechanical behavior of such alloys as Al-Cu are directly influenced by some parameters such as composition, cooling velocity and homogenization process.

Beyond Ni-based superalloys: Development of CoRe-based alloys for gas turbine applications at very high temperatures

2011 ◽  
Vol 102 (9) ◽  
pp. 1125-1132 ◽  
Author(s):  
Debashis Mukherji ◽  
Joachim Rösler ◽  
Pavel Strunz ◽  
Ralph Gilles ◽  
Gerhard Schumacher ◽  
...  
Keyword(s):  
Gas Turbine ◽  
High Temperatures ◽  
Very High
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