Thermal stress induced failure of (0001) sapphire using CO2 laser heating

Author(s):  
O. Esquivel ◽  
J. Barie ◽  
P. Chaffee ◽  
D. Platus
2012 ◽  
Vol 44 (2) ◽  
pp. 463-470 ◽  
Author(s):  
O. Momin ◽  
S.Z. Shuja ◽  
B.S. Yilbas

Author(s):  
Mingsheng Luo ◽  
Yongxiang Hu ◽  
Dong Qian ◽  
Zhenqiang Yao

Laser-assisted laser peen forming (LALPF) is proposed as a hybrid process to combine laser heating and laser peening to improve the bending capability of laser peen forming (LPF) effectively. To predict LALPF-induced bending deformation and mechanism of bending capability improvement, a sequentially coupled modeling approach is established by integrating three models, i.e., a thermoelastic-plastic model to predict the temperature, a dynamic model to obtain the eigenstrain of laser shock, and an eigenstrain model to predict the bending deformation. The effects of temperature, thermal stress, and thermal plastic strain of laser heating and the coupling effects on the bending deformation were investigated. The results show that the interaction of temperature and thermal stress are the dominant factors contributing to the improvement of bending capability.


2015 ◽  
Vol 86 (6) ◽  
pp. 063905 ◽  
Author(s):  
Jin S. Zhang ◽  
Jay D. Bass ◽  
Gaohua Zhu

Author(s):  
Joseph P. Abrahamson ◽  
Ramakrishnan Rajagopalan ◽  
Randy L. Vander Wal

Porous graphite was prepared without the use of template by rapidly heating the carbonization products from mixtures of anthracene, flourene, and pyrene with a CO2 laser. Rapid CO2 laser heating at a rate of 1.8 × 10 6 °C/s vaporizes out the fluorene-pyrene derived pitch while annealing the anthracene coke. The resulting structure is that of graphite with 100 nm spherical pores. The graphitizablity of the porous material is the same as pure anthracene coke. Transmission electron microscopy revealed that the interface between graphitic layers and the pore walls are unimpeded. Traditional furnace annealing does not result in the porous structure as the heating rates are too slow to vaporize out the pitch, thereby illustrating the advantage of fast thermal processing. The resultant porous graphite was prelithiated and used as an anode in lithium ion capacitors. The porous graphite when lithiated had a specific capacity of 200 mAh/g at 100 mA/g. The assembled lithium ion capacitor demonstrated an energy density as high as 75 Wh/kg when cycled between 2.2 V to 4.2 V.


Sign in / Sign up

Export Citation Format

Share Document