Rock is generally complex and heterogeneous,therefore the heterogeneity effects of effective stress and temperature on permeability should be taken into account.In this study,two-part Hooke’s model（TPHM） is introdu...Rock is generally complex and heterogeneous,therefore the heterogeneity effects of effective stress and temperature on permeability should be taken into account.In this study,two-part Hooke’s model（TPHM） is introduced to understand the influences of effective stress and temperature on permeability of soft and hard parts（two parts） of rock based on coupling thermo-hydro-mechanical tests.Under a fixed temperature level（25 ℃.35 ℃.50 ℃.65 ℃.80 ℃.90 ℃ and 95 ℃）.the tests were carried out in a conventional triaxial system whereas the confining pressure was remained at 50 MPa.and the pore pressure was increased to the specified levels step by step.i.e.8 MPa,18 MPa.28 MPa.38 MPa.41 MPa,44 MPa.46 MPa and 48 MPa.The temperature-dependent relationships for two parts permeabilities are proposed on the basis of the initial test results.We point out that temperature of 65 ℃-90 ℃ is the threshold for the development of CO2-plume geothermal（CPC） reservoir sandstone cracking under low effective stress（2-9 MPa） based on the relationship between temperature and soft part permeability.Furthermore,we discuss the effect of temperature on the two parts in the rock.The results indicate that as the temperature increases from 25 ℃ to 65 ℃.the flow channel in the hard part has a stronger response to temperature than that in the soft part at a fixed effective stress level,which is opposite to the situation of effective stress.Considering that natural rock is generally heterogeneous with non-uniform pore structure,we suggest a physical interpretation of the phenomenon that before the thermal cracking threshold the two parts have different responses to temperature.展开更多
Nanolaminated structures composed of low-angle grain boundaries(LAGBs) possess high thermal stability. In this paper, a gradient nanolaminated(GNL) surface layer with smooth finish was fabricated on an interstitial-fr...Nanolaminated structures composed of low-angle grain boundaries(LAGBs) possess high thermal stability. In this paper, a gradient nanolaminated(GNL) surface layer with smooth finish was fabricated on an interstitial-free steel by means of surface mechanical rolling treatment. Microstructural observations demonstrated that the average lamellar thickness is about 80 nm in the topmost surface layer and increases with increasing depth. High thermal stability was confirmed in the GNL surface layer after annealing at 500℃. Diffusion measurements showed that effective diffusivity of Cr in GNL layer is 4–6 orders of magnitude higher than lattice diffusivity within the temperature range from 400 to 500℃. This might be attributed to numerous LAGBs or dislocation structures with a higher energy state in the GNL surface layer. This work demonstrates the possibility to advanced chromizing(or other surface alloying)processes of steels with formation of GNL surface layer, so that a thicker alloyed surface layer with a stable nanostructure is achieved.展开更多
Relaxor ferroelectrics have different properties from that of the normal ferroelectrics,such as dielectric properties with diffuse phase transition and frequency dispersion,specific heat,birefringence,elastic constan...Relaxor ferroelectrics have different properties from that of the normal ferroelectrics,such as dielectric properties with diffuse phase transition and frequency dispersion,specific heat,birefringence,elastic constants and Raman scattering,etc.It is considered that the different properties are related with the polar nanoregions in relaxors.In this work we briefly introduce how we use the high spatial resolution analytical electron microscopy and high resolution electron microscopy methods to investigate the polar nanoregion in Pb(Mg_(1/3)Nb_(2/3))O_(3)(PMN),Pb(Mg_(1/3)Nb_(2/3))O_(3)PbTiO_(3)(PMNPT)and Ba(Ti_(1-x)Sn_(x))O_(3)(BTSn).The main experimental results110 are as mentioned in next three parts.展开更多
基金financially supported by the International Science&Technology Cooperation Program of China(Grant No.2012DFA60760)
文摘Rock is generally complex and heterogeneous,therefore the heterogeneity effects of effective stress and temperature on permeability should be taken into account.In this study,two-part Hooke’s model（TPHM） is introduced to understand the influences of effective stress and temperature on permeability of soft and hard parts（two parts） of rock based on coupling thermo-hydro-mechanical tests.Under a fixed temperature level（25 ℃.35 ℃.50 ℃.65 ℃.80 ℃.90 ℃ and 95 ℃）.the tests were carried out in a conventional triaxial system whereas the confining pressure was remained at 50 MPa.and the pore pressure was increased to the specified levels step by step.i.e.8 MPa,18 MPa.28 MPa.38 MPa.41 MPa,44 MPa.46 MPa and 48 MPa.The temperature-dependent relationships for two parts permeabilities are proposed on the basis of the initial test results.We point out that temperature of 65 ℃-90 ℃ is the threshold for the development of CO2-plume geothermal（CPC） reservoir sandstone cracking under low effective stress（2-9 MPa） based on the relationship between temperature and soft part permeability.Furthermore,we discuss the effect of temperature on the two parts in the rock.The results indicate that as the temperature increases from 25 ℃ to 65 ℃.the flow channel in the hard part has a stronger response to temperature than that in the soft part at a fixed effective stress level,which is opposite to the situation of effective stress.Considering that natural rock is generally heterogeneous with non-uniform pore structure,we suggest a physical interpretation of the phenomenon that before the thermal cracking threshold the two parts have different responses to temperature.
基金Financial supports from the National Key Research and Development Program of China (No. 2017YFA0204401)Shenyang National Laboratory for Materials Science (No. 2015RP04)
文摘Nanolaminated structures composed of low-angle grain boundaries(LAGBs) possess high thermal stability. In this paper, a gradient nanolaminated(GNL) surface layer with smooth finish was fabricated on an interstitial-free steel by means of surface mechanical rolling treatment. Microstructural observations demonstrated that the average lamellar thickness is about 80 nm in the topmost surface layer and increases with increasing depth. High thermal stability was confirmed in the GNL surface layer after annealing at 500℃. Diffusion measurements showed that effective diffusivity of Cr in GNL layer is 4–6 orders of magnitude higher than lattice diffusivity within the temperature range from 400 to 500℃. This might be attributed to numerous LAGBs or dislocation structures with a higher energy state in the GNL surface layer. This work demonstrates the possibility to advanced chromizing(or other surface alloying)processes of steels with formation of GNL surface layer, so that a thicker alloyed surface layer with a stable nanostructure is achieved.
文摘Relaxor ferroelectrics have different properties from that of the normal ferroelectrics,such as dielectric properties with diffuse phase transition and frequency dispersion,specific heat,birefringence,elastic constants and Raman scattering,etc.It is considered that the different properties are related with the polar nanoregions in relaxors.In this work we briefly introduce how we use the high spatial resolution analytical electron microscopy and high resolution electron microscopy methods to investigate the polar nanoregion in Pb(Mg_(1/3)Nb_(2/3))O_(3)(PMN),Pb(Mg_(1/3)Nb_(2/3))O_(3)PbTiO_(3)(PMNPT)and Ba(Ti_(1-x)Sn_(x))O_(3)(BTSn).The main experimental results110 are as mentioned in next three parts.
