Unnamed Corundum Crystal

2009 ◽  
pp. 891-891
Keyword(s):  
Corundum Crystal

The thermal conductivities of some dielectric solids at low temperatures (Experimental)

1951 ◽  
Vol 208 (1092) ◽  
pp. 90-108 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Specific Heat ◽  
Temperature Variation ◽  
Temperature Region ◽  
Low Temperatures ◽  
Quartz Crystal ◽  
Corundum Crystal ◽  
Before And After ◽  
Dielectric Solids

An apparatus is described in which the thermal conductivity of solids can be determined at any temperature between 2 and 90°K. Several glasses and dielectric crystals have been measured. It had previously been found that at high temperatures the conductivity of glasses is proportional to the specific heat, but at low temperatures it falls off more slowly than the specific heat. The present experiments show that there is a temperature region in which the conductivity is nearly independent of temperature. A similar variation of conductivity is found for the thermo-plastic Perspex. The effect of lattice defects in crystals was studied by measuring the thermal conductivity of a quartz crystal before and after successive periods of neutron irradiation. After prolonged irradiation the conductivity approached, in both magnitude and temperature variation, that of quartz glass. Subsequent heating produced a substantial recovery in the conductivity. The results on both glasses and on crystals can be explained by the theory developed by Klemens (1951). Further measurements made on a corundum crystal confirm the importance of the ‘Umklapp’ processes, postulated by Peierls, in causing thermal resistance.

Quantum-chemical simulations of free and bound hole polarons in corundum crystal

1997 ◽  
Vol 7 (3) ◽  
pp. 285-294 ◽  
Author(s):  
Yu.F. Zhukovskii ◽  
E.A. Kotomin ◽  
R.M. Nieminen ◽  
A. Stashans
Keyword(s):  
Quantum Chemical ◽  
Corundum Crystal

V4+ in Corundum: Crystal Growth and Spectroscopy

1987 ◽  
Author(s):  
H. Verdun ◽  
U. Brauch ◽  
G. de la Fuente ◽  
L. Thomas ◽  
E. Behrens ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Corundum Crystal

Phenomenology of corundum crystal formation in supercritical water fluid

2004 ◽  
Vol 16 (14) ◽  
pp. S1215-S1221 ◽  
Author(s):  
G P Panasyuk ◽  
M N Danchevskaya ◽  
V N Belan ◽  
I L Voroshilov ◽  
Yu D Ivakin
Keyword(s):  
Supercritical Water ◽  
Crystal Formation ◽  
Corundum Crystal ◽  
Supercritical Water Fluid

scholarly journals Morphology and Chemical Composition of Silicon Carbide Surface in Interaction with Titanium Alloy under Micro-Scratching Conditions

2020 ◽  
Vol 329 ◽  
pp. 02010
Author(s):  
Vladimir Nosenko ◽  
Aleksandr Fetisov ◽  
Sergey Nosenko ◽  
Valeria Puzyrkova
Keyword(s):  
Silicon Carbide ◽  
Titanium Alloy ◽  
Chemical Composition ◽  
Path Length ◽  
Chemical Elements ◽  
Cooling Process ◽  
Corundum Crystal ◽  
Initial Shape ◽  
X Ray ◽  
Cutting Path

The article describes features of the wear site morphology formation during micro-scratching of a titanium alloy by a silicon carbide crystal in comparison with a corundum crystal. The initial shape of the crystal top and the rate of micro-scratching were assumed to be constant. No lubricating or cooling process media were used. External factors: micro-scratch depth and cutting path length. The chemical composition of wear sites was studied using micro-x-ray spectral analysis. The content of chemical elements in the surface layer of silicon carbide and adhered metal was studied at separate points and by area scanning. The accelerating voltage of the excitation electrons was changed in the range from 5 to 20 kV. The concentration of chemical elements on the surface of the wear site was determined immediately after micro-scratching and after removing the adhered metal by etching. The regularities of changes in the concentration of chemical elements depending on the accelerating voltage of the excitation electrons were determined.

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