scholarly journals Room temperature crack-healing in an atomically layered ternary carbide

2021 ◽  
Vol 7 (33) ◽  
pp. eabg2549
Author(s):  
Hemant J. Rathod ◽  
Thierry Ouisse ◽  
Miladin Radovic ◽  
Ankit Srivastava
Keyword(s):  
Room Temperature ◽  
Ceramic Materials ◽  
Crack Healing ◽  
Ternary Carbide ◽  
Catastrophic Fracture ◽  
Crystallographic Planes ◽  
Traditional Approaches ◽  
Hostile Environments ◽  
Layered Ceramic ◽  
Temperature Crack

Ceramic materials provide outstanding chemical and structural stability at high temperatures and in hostile environments but are susceptible to catastrophic fracture that severely limits their applicability. Traditional approaches to partially overcome this limitation rely on activating toughening mechanisms during crack growth to postpone fracture. Here, we demonstrate a more potent toughening mechanism that involves an intriguing possibility of healing the cracks as they form, even at room temperature, in an atomically layered ternary carbide. Crystals of this class of ceramic materials readily fracture along weakly bonded crystallographic planes. However, the onset of an abstruse mode of deformation, referred to as kinking in these materials, induces large crystallographic rotations and plastic deformation that physically heal the cracks. This implies that the toughness of numerous other layered ceramic materials, whose broader applications have been limited by their susceptibility to catastrophic fracture, can also be enhanced by microstructural engineering to promote kinking and crack-healing.

scholarly journals Electrochemically assisted room‐temperature crack healing of ceramic‐based composites

2019 ◽  
Vol 102 (7) ◽  
pp. 4236-4246 ◽  
Author(s):  
Shengfang Shi ◽  
Tomoyo Goto ◽  
Sunghun Cho ◽  
Tohru Sekino
Keyword(s):  
Room Temperature ◽  
Crack Healing ◽  
Temperature Crack

Development of Ti dispersed ZrO2 composites and their room-temperature crack-healing behaviors

2021 ◽  
Vol 851 ◽  
pp. 156895
Author(s):  
Shengfang Shi ◽  
Tomoyo Goto ◽  
Sunghun Cho ◽  
Tohru Sekino
Keyword(s):  
Room Temperature ◽  
Crack Healing ◽  
Temperature Crack

scholarly journals Effect of LiNbO3 on the Electrocaloric Performance of 0.94BNT-0.06BT Ceramic Materials

2021 ◽  
Author(s):  
Jing Chen ◽  
lei Wu ◽  
Luanfan Duan ◽  
Dongren Liu
Keyword(s):  
Ceramic Material ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Adiabatic Temperature ◽  
Cooling Effect ◽  
Material System ◽  
Temperature Changes ◽  
Cooling Temperature ◽  
Temperature Range

Abstract Considering that the electric refrigeration temperature range of 0.94BNT-0.06BT ceramic materials is 100 ~ 140℃, the electric refrigeration performance of the 0.94BNT-0.06BT ceramic material system was modified by LiNbO3 doping to reduce the cooling temperature. As a result, the refrigeration temperature range of the 0.94BNT-0.06BT ceramic material system was lowered to 25 ~ 80℃, achieving its cooling effect near room temperature, and in this temperature range, the adiabatic temperature changes ∆T > 0.6K.

Temperature Dependence of Thermal Conductivity of Electronic Ceramics by an Improved Flash Diffusivity Technique

1989 ◽  
Vol 167 ◽  
Author(s):  
R. C. Enck ◽  
R. D. Harris
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Laser Flash ◽  
Flow Measurements ◽  
Electronic Ceramics ◽  
Temperature Dependences ◽  
Commercial Sources ◽  
Materials Used ◽  
Flash Diffusivity

AbstractThe thermal conductivity of ceramic materials used for IC substrates and packages has increased in importance as chip sizes have decreased and heat loads have risen. AIN which has a room temperature (RT) thermal conductivity (λ) greater than 200 W/m·K and BeO with λ(RT) ∼260 W/m·K are the major candidates for applications demanding high conductivity. Conflicting reports of the temperature dependences of λ for these materials over the range of interest for packaging use (≤200°C) have been published, with some reports suggesting a crossover in λ. These reported differences may be due to the reported problems in measuring λ in AIN using the flash diffusivity method. For the present experiments, we have used a new long wavelength laser flash diffusivity system which has been shown to determine thermal diffusivity to better than ± 3% for AIN with sample thicknesses ranging from 0.3 mm to 5 mm. No absorbinq coatings are required and no correction factors are needed to fit the data to theory. We report λ from room temperature to 400°C for AIN from a number of commercial sources, and for BeO and SiC. At room temperature, BeO has the highest thermal conductivity, but as the temperature is raised, the values for BeO and AIN approach one another, with crossover observed at about 350°C for the highest conductivity AIN sample studied. Recent steady state heat flow measurements agree with our thermal conductivity values rather than with previous literature values.

Polaronic conduction in lanthanum strontium chromite

1977 ◽  
Vol 55 (19) ◽  
pp. 1725-1731 ◽  
Author(s):  
J. B. Webb ◽  
M. Sayer ◽  
A. Mansingh
Keyword(s):  
Transport Properties ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Localized States ◽  
Defect Band ◽  
Barrier Effects ◽  
Lanthanum Strontium ◽  
Dc And Ac Conductivity ◽  
Polycrystalline Ceramic ◽  
Polaron Radius

In many polycrystalline ceramic materials the transport properties are strongly affected by internal barrier effects or by the presence of contact barriers. The transport properties of La1−xSrxCrO3, 0 ≤ x ≤ 0.2 have been investigated and the degree to which these barriers affect the measured transport properties has been established. Measurements of the dc and ac conductivity in the range 77 K ≤ T ≤ 1300 K are consistent with the hopping of polarons in a defect band of localized states at the Fermi energy with the thermopower essentially independent of temperature. A polaron radius of 3.5 Å has been determined with room temperature mobility of 5 × 10−4 cm2 V−1 s−1.

Compressive Properties of Quartzite Microcrystallite Glass Ceramics

2007 ◽  
Vol 353-358 ◽  
pp. 469-472
Author(s):  
Qiu Ming Zhang ◽  
Xiao Dong He ◽  
Yao Li
Keyword(s):  
Room Temperature ◽  
Ageing Time ◽  
Glass Ceramics ◽  
Ceramic Materials ◽  
Compressive Property ◽  
Compressive Properties ◽  
Smooth Curves ◽  
Elastic Module ◽  
Machinable Ceramic ◽  
Higher Temperature

Quartzite microcrystallite glass ceramics is one of the most promising machinable ceramic materials due to its many outstanding properties. The density of quartzite microcrystallite glass ceramics is smaller than the aluminum alloy and its thermal conductivity approaches to the zirconia and its elastic module is also very small; All these advantages meet the requirements for structural components to work at higher temperature; Compressive properties of quartzite microcrystallite glass ceramics had been studied at room temperature and 500°C in this paper; The specimens had been aged at 1000°C for 5, 10, 20, 30 hours, respectively. Through SEM observations of the fracture surface of the specimens, the microstructural changes had been determined; The tests showed: the compressive property of the machinable glass ceramic declined as the ageing time increasing; but the compressive property of the specimen aged for 10 hours was inferior to that aged for 20 hours; Then compressive property declined as the ageing time increasing. The SEM observation indicated that with the extend of ageing time, the grains grew bigger and microporous and microcracks increased in the specimens; Comparing the compressive property at room temperature with that at 500°C, one found that the change of compressive property was very small when the ageing time was the same; With the extend of ageing time, the curve of the compressive property changed from smooth curves to broken lines.

A reinterpretation of monalbite

1967 ◽  
Vol 36 (277) ◽  
pp. 80-82 ◽  
Author(s):  
William L. Brown
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Room Temperature ◽  
Ceramic Materials

SummaryA neutron activation analysis of one of the crystals of ‘monalbite’, which was monoclinic at room temperature, shows that it contains a large proportion of potassium. It is thus not a polymorph of pure NaAlSi3O8. The contamination occurred by transfer of K through the atmosphere of the furnace from potassium-bearing ceramic materials.

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