The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree ...The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree of damage is different, were selected from Tongchun, Qilin, and Pingdingshan mines. Using a series of experiments in an electrostatic field, we analyzed the characteristics of gas adsorption and diffusion in tectonic coal. We found that gas adsorption in coal conforms to the Langmuir equation in an electrostatic field. Both the depth of the adsorption potential well and the coal molecular electroneg- ativity increases under the action of an electrostatic field. A Joule heating effect was caused by changing the coal-gas system conductivity in an electrostatic field. The quantity of gas adsorbed and AP result from competition between the depth of the adsorption potential well, the coal molecular electronegativ- ity, and the Joule heating effect. △P peaks when the three factors control behavior equally. Compared with anthracite, the impact of the electrostatic field on the gas diffusion capacity of middle and high rank coals is greater. Compared with the original coal, the gas adsorption quantity,△P, and the gas diffusion capacity of tectonic coal are greater in an electrostatic field. In addition, the smaller the particle size of tectonic coal, the larger the△P.展开更多
To realize numerical simulation of rolling and obtain the hot forming process parameters for X70 HD steel, the flow stress behaviors of X70 HD steel were investigated under different temperatures（820-1100 ℃ and stra...To realize numerical simulation of rolling and obtain the hot forming process parameters for X70 HD steel, the flow stress behaviors of X70 HD steel were investigated under different temperatures（820-1100 ℃ and strain rates（0.01-10 s-1） on a Gleeble-3500 thermo-simulation machine. A new flow stress model was established. The linear and exponential relationship methods were applied to the parameters with respect to temperature and deformation rates. The rise of curve ends under certain conditions was analyzed. The flow stress of X70 HD steel predicted by the proposed model agrees well with the experimental results. So, it greatly improves the precision of the metal thermoplastic processing through finite element method and practical application of engineering.展开更多
Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet ...Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD (X-ray diffraction) are formed based on mechanics effects of laser thermal stress. The mechanisms of sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD are analyzed, and the theory of photo-mechanics manufacturing and detecting technologies based on laser thermal stress is originally put forward, whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.展开更多
A modified theoretical model is proposed to predict the grain boundary segregation of impurity atoms during high temperature plastic deformation. The model is based on the supersaturated vacancy-impurity complex creat...A modified theoretical model is proposed to predict the grain boundary segregation of impurity atoms during high temperature plastic deformation. The model is based on the supersaturated vacancy-impurity complex created by plastic deformation and involves quasi-thermodynamics and kinetics. Model predictions are made for phosphorus grain boundary segregation during plastic deformation in ferrite steel. The results reveal that phosphorus segregates at grain boundaries during plastic deformation. At a given temperature, under a certain strain rate the segregation increases with increasing deformation amount until reaching a steady value, and at the same deformation amount it increases with increasing strain rate. The predicted results are compared with the available experimental values, indicating that there is a reasonable agreement between the theoretical predictions and the experimental observations.展开更多
基金the National Natural Science Foundation of China(No.41272177)the Henan Polytechnic University Doctor Foundation(No.WS2013A11)
文摘The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree of damage is different, were selected from Tongchun, Qilin, and Pingdingshan mines. Using a series of experiments in an electrostatic field, we analyzed the characteristics of gas adsorption and diffusion in tectonic coal. We found that gas adsorption in coal conforms to the Langmuir equation in an electrostatic field. Both the depth of the adsorption potential well and the coal molecular electroneg- ativity increases under the action of an electrostatic field. A Joule heating effect was caused by changing the coal-gas system conductivity in an electrostatic field. The quantity of gas adsorbed and AP result from competition between the depth of the adsorption potential well, the coal molecular electronegativ- ity, and the Joule heating effect. △P peaks when the three factors control behavior equally. Compared with anthracite, the impact of the electrostatic field on the gas diffusion capacity of middle and high rank coals is greater. Compared with the original coal, the gas adsorption quantity,△P, and the gas diffusion capacity of tectonic coal are greater in an electrostatic field. In addition, the smaller the particle size of tectonic coal, the larger the△P.
基金Project(51304171)supported by the National Natural Science Foundation of ChinaProject(E2013203248)supported by Natural Science Foundation of Hebei Province of ChinaProject(NECSR-201209)supported by Open Foundation of the National Engineering Research Center for Equipment and Technology of Cold Rolling Strip,China
文摘To realize numerical simulation of rolling and obtain the hot forming process parameters for X70 HD steel, the flow stress behaviors of X70 HD steel were investigated under different temperatures（820-1100 ℃ and strain rates（0.01-10 s-1） on a Gleeble-3500 thermo-simulation machine. A new flow stress model was established. The linear and exponential relationship methods were applied to the parameters with respect to temperature and deformation rates. The rise of curve ends under certain conditions was analyzed. The flow stress of X70 HD steel predicted by the proposed model agrees well with the experimental results. So, it greatly improves the precision of the metal thermoplastic processing through finite element method and practical application of engineering.
基金this research from the Scientific Research Fund of Jiangsu Polytechnic University(GrantNo.ZMF07020042)Fund of Jiangsu ProvincialKey Laboratory for Science and Technology of Photo-manufacroring (Grant No.GZ-1-02)the NaturalScience Foundation of the Jiangsu Higher EducationInstitutions of China( Grant No. 08KJB430002 ) is gratefully acknowledged.
文摘Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD (X-ray diffraction) are formed based on mechanics effects of laser thermal stress. The mechanisms of sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD are analyzed, and the theory of photo-mechanics manufacturing and detecting technologies based on laser thermal stress is originally put forward, whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.
基金supported by the National Natural Science Foundation of China (Grant No. 50671033)the Department of Science and Technology of Shenzhen (Grant No. SY200806260037A)
文摘A modified theoretical model is proposed to predict the grain boundary segregation of impurity atoms during high temperature plastic deformation. The model is based on the supersaturated vacancy-impurity complex created by plastic deformation and involves quasi-thermodynamics and kinetics. Model predictions are made for phosphorus grain boundary segregation during plastic deformation in ferrite steel. The results reveal that phosphorus segregates at grain boundaries during plastic deformation. At a given temperature, under a certain strain rate the segregation increases with increasing deformation amount until reaching a steady value, and at the same deformation amount it increases with increasing strain rate. The predicted results are compared with the available experimental values, indicating that there is a reasonable agreement between the theoretical predictions and the experimental observations.
