期刊文献+
共找到627篇文章
< 1 2 32 >
每页显示 20 50 100
Experimental Investigation on Fracturing Behaviors after Liquid Nitrogen Pre-Injection in High-Temperature Sandstone
1
作者 Decheng Li Yan Zhang +2 位作者 Dongdong Ma Haozhe Geng Yu Wu 《Energy Engineering》 EI 2023年第11期2503-2516,共14页
The fracturing process of sandstone is inherently complex due to its loose internal structure and deformation adaptability.Liquid nitrogen pre-injection has emerged as a promising approach to damage reservoir rocks,ef... The fracturing process of sandstone is inherently complex due to its loose internal structure and deformation adaptability.Liquid nitrogen pre-injection has emerged as a promising approach to damage reservoir rocks,effectively reducing fracture pressure and establishing intricate fracture networks,thus offering a potential solution for reservoir reconstruction.To unravel the fundamental mechanisms governing sandstone fracturing behaviors following liquid nitrogen pre-injection,sandstone fracturing experiments were conducted under varying durations of liquid nitrogen injection,rock temperature,and in-situ stress conditions.The experiments showcased the evolution of injection pressure and fracture characteristics under different testing conditions,complemented by electron microscope analysis to elucidate the factors driving the complex fracture characteristics of sandstone.The findings revealed a significant decrease in fracture pressure after liquid nitrogen pre-injection,accompanied by a notable increase in the complexity of the fracture network and the roughness of the fracture surface.Moreover,prolonging the duration of liquid nitrogen injection and elevating reservoir temperature further contributed to reducing fracture pressure,consequently enhancing fracture complexity and surface roughness.Conversely,the application of confining pressure amplified fracture pressure while intensifying the degree of fracturing.Notably,the investigation highlighted the increased presence of microcracks in sandstone resulting from liquid nitrogen preinjection,facilitating fluid diffusion during fracturing and yielding lower fracture pressures,thereby enhancing the effectiveness of sandstone reservoir reformation.The research results can provide theoretical guidance for geothermal reservoir reconstruction. 展开更多
关键词 SANDSTONE high temperature liquid nitrogen pre-injection fracturing behaviors
下载PDF
Quasi-static and low-velocity impact mechanical behaviors of entangled porous metallic wire material under different temperatures
2
作者 Yi-wan Wu Hu Cheng +3 位作者 Shang-zhou Li Yu Tang Hong-bai Bai Chun-hong Lu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第1期143-152,共10页
To improve the defense capability of military equipment under extreme conditions,impact-resistant and high-energy-consuming materials have to be developed.The damping characteristic of entangled porous metallic wire m... To improve the defense capability of military equipment under extreme conditions,impact-resistant and high-energy-consuming materials have to be developed.The damping characteristic of entangled porous metallic wire materials(EPMWM)for vibration isolation was previously investigated.In this paper,a study focusing on the impact-resistance of EPMWM with the consideration of ambient temperature is presented.The quasi-static and low-velocity impact mechanical behavior of EPMWM under different temperatures(25℃-300℃)are systematically studied.The results of the static compression test show that the damping energy dissipation of EPMWM increases with temperature while the nonlinear damping characteristics are gradually enhanced.During the impact experiments,the impact energy loss rate of EPMWM was between 65%and 85%,while the temperatures increased from 25℃to 300℃.Moreover,under the same drop impact conditions,the overall deformation of EPMWM decreases in the temperature range of 100℃-200℃.On the other hand,the impact stiffness,energy dissipation,and impact loss factor of EPMWM significantly increase with temperature.This can be attributed to an increase in temperature,which changes the thermal expansion coefficient and contact state of the internal wire helixes.Consequently,the energy dissipation mode(dry friction,air damping,and plastic deformation)of EPMWM is also altered.Therefore,the EPMWM may act as a potential candidate material for superior energy absorption applications. 展开更多
关键词 Entangled porous metallic wire material Low-velocity impact high temperature Energy dissipation characteristics Mechanical behavior
下载PDF
High-temperature frictional wear behavior of MCrAlY-based coatings deposited by atmosphere plasma spraying 被引量:4
3
作者 Chong Tao Lei Wang Xiu Song 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2017年第2期222-228,共7页
Al2O3-r2O03/NiCoCrAIYTa coatings were prepared via atmosphere plasma spraying (APS). The microstructure and phase com- position of the coatings were analyzed by X-ray diffraction (XRD), scanning electron microsco... Al2O3-r2O03/NiCoCrAIYTa coatings were prepared via atmosphere plasma spraying (APS). The microstructure and phase com- position of the coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser confocal scanning microsco- py (LSCM), and transmission electron microscopy (TEM). The dry frictional wear behavior of the coatings at 500℃ in static air was inves- tigated and compared with that of 0Cr25Ni20 steel. The results show that the coatings comprise the slatted layers of oxide phases, unmelted particles, and pores. The hot abrasive resistance of the coatings is enhanced compared to that of 0Cr25Ni20, and their mass loss is approxi- mately one-fifteenth that of 0Cr25Ni20 steel. The main wear failure mechanisms of the coatings are abrasive wear, fatigue wear, and adhe- sive wear. 展开更多
关键词 metal matrix composites composite coatings wear behavior high temperature properties plasma spraying
下载PDF
Dynamic compressive property and failure behavior of extruded Mg-Gd-Y alloy under high temperatures and high strain rates 被引量:9
4
作者 Jin-cheng Yu Zheng Liu +1 位作者 Yang Dong Zhi Wang 《Journal of Magnesium and Alloys》 SCIE EI CAS 2015年第2期134-141,共8页
For the purpose of investigating the dynamic deformational behavior and failure mechanisms of magnesium under high strain rates,the Split Hopkinson Pressure Bar(SHPB)was used for investigating dynamic mechanical prope... For the purpose of investigating the dynamic deformational behavior and failure mechanisms of magnesium under high strain rates,the Split Hopkinson Pressure Bar(SHPB)was used for investigating dynamic mechanical properties of extruded Mg-Gd-Y Magnesium alloy at ambient temperature(300 K),200℃(473 K)and 300℃(573 K)temperature.The samples after compression were analyzed by scanning electron microscope(SEM)and metallographic microscope.Dynamic mechanical properties,crack performance and plastic deformation mechanism of extruded Mg-Gd-Y Magnesium alloy along the extrusion direction(ED)were discussed.The results show that,extruded Mg-Gd-Y Magnesium alloy has the largest dynamic compressive strength which is 535 MPa at ambient temperature(300 K)and strain rate of 2826 s^(−1).When temperature increases,dynamic compressive strength decreases,while ductility increases.The dynamic compression fracture mechanism of extruded Mg-Gd-Y Magnesium alloy is multi-crack propagation and intergranular quasi-cleavage fracture at both ambient temperature and high temperature.The dynamic compressive deformation mechanism of extruded Mg-Gd-Y Magnesium alloy is a combination of twinning,slipping and dynamic recrystallization at both ambient temperature and high temperature. 展开更多
关键词 Extruded Mg-Gd-Y magnesium alloy Split Hopkinson Pressure Bar Dynamic compressive property Failure behavior high strain rates high temperature
下载PDF
Behavior of concrete and concrete-filled circular steel tubular stub columns at constant high temperatures 被引量:8
5
作者 丁发兴 余志武 《Journal of Central South University of Technology》 EI 2006年第6期726-732,共7页
Based on reanalyzing test results of uniaxial compressive behavior of concrete at constant high temperatures in China, with the compressive cube strength of concrete from 20 to 80 MPa, unified formulas for uniaxial co... Based on reanalyzing test results of uniaxial compressive behavior of concrete at constant high temperatures in China, with the compressive cube strength of concrete from 20 to 80 MPa, unified formulas for uniaxial compressive strength, elastic modulus, strain at peak uniaxial compression and mathematical expression for unaxial compressive stress-strain relations for the concrete at constant high temperatures were studied. Furthermore, the axial stress-axial strain relations between laterally confined concrete under axial compression and multiaxial stress-strain relations for steel at constant high temperatures were studied. Finally, based on continuum mechanics, the mechanics model for concentric cylinders of circular steel tube with concrete core of entire section loaded at constant high temperatures was established. Applying elasto-plastic analysis method, a FORTRAN program was developed, and the concrete-filled circular steel tubular (CFST) stub colunms at constant high temperatures were analyzed. The analysis results are in agreement with the experiment ones from references. 展开更多
关键词 CONCRETE concrete-filled steel tubular colunm behavior high temperature
下载PDF
Microstructure and abrasion wear behavior of Ni-based laser cladding alloy layer at high temperature 被引量:3
6
作者 刘勇 刘素芹 王顺兴 《Journal of Central South University of Technology》 EI 2005年第4期403-405,共3页
Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high t... Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+ 0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature. 展开更多
关键词 Ni-based laser cladding layer MICROSTRUCTURE abrasion wear behavior high temperature
下载PDF
Effect of the precipitation state on high temperature tensile and creep behaviors of Mg-15Gd alloy 被引量:2
7
作者 Shuxia Ouyang Guangyu Yang +3 位作者 He Qin Chunhui Wang Shifeng Luo Wanqi Jie 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2022年第12期3459-3469,共11页
Due to the effective precipitation strengthening effect of the β phase, Mg-Gd alloys exhibit excellent room temperature mechanical behaviors. However, when served at high temperatures, the metastable β phase will tr... Due to the effective precipitation strengthening effect of the β phase, Mg-Gd alloys exhibit excellent room temperature mechanical behaviors. However, when served at high temperatures, the metastable β phase will transform to other phases, resulting in severe performance degradation. In this study, we investigated the effect of precipitation state achieved by different heat treatments on high temperature tensile and creep behaviors of the Mg-15Gd alloy by comparing the properties of the as-cast, solid-solutioned(T4) and peak-aged(T6) alloys. The results showed that the tensile mechanical properties of the T6 alloy were always highest from room temperature to 300 ℃, in spite of an abnormal strength increase with temperature existed in the T4 alloy. For tensile creep properties, the T6 alloy exhibited the lowest steady creep rate below 235 ℃ while the T4 alloy possessed the best properties above 260 ℃. Microstructure characterization revealed that the transition was caused by the stress-promoted precipitation of β phase in the T4 alloy and rapid phase transformation in the T6 alloy at high temperatures. At 260 ℃, the calculated stress exponent n was 3.1 and 2.8 for the T4 and T6 alloys, respectively, suggesting the creep deformation mechanism was dislocation slip, which was further confirmed by the microstructure after creeping. Our findings can provide new insights into the heat treatment process of Mg-Gd alloys served at high temperatures. 展开更多
关键词 Mg-Gd alloys Precipitation state high temperature tensile properties Tensile creep behaviors Stress-promoted precipitation
下载PDF
High-temperature oxidation behavior of CeO_2-SiO_2/Ni-W-P composites 被引量:3
8
作者 徐瑞东 王军丽 +1 位作者 郭忠诚 王华 《中国有色金属学会会刊:英文版》 EI CSCD 2009年第5期1190-1195,共6页
Ni-W-P matrix composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by means of pulse electrodeposition,and the high-temperature oxidation behavior was investigated.The result... Ni-W-P matrix composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by means of pulse electrodeposition,and the high-temperature oxidation behavior was investigated.The results show that when the oxidation time is controlled in 1 h,oxidation kinetics curve between oxidation mass gain rate and oxidation temperature of CeO2-SiO2/Ni-W-P composites accords with the index increasing law.When the oxidation temperature is controlled at 300℃,the kinetics curve between oxidation mass gain rate and oxidation time accords with the linear increasing law.The composites as-deposited are in the amorphous state and turn into the crystal state at 400℃.The microstructures of oxidation film on the composites will change from the compact state to the loose state with increasing oxidation temperature to 800℃.They are still continuous and compact,and there are no crackle,strip and falling-out.CeO2 and SiO2 nano-particles co-deposited into Ni-W-P alloy can improve the high-temperature oxidation resistance. 展开更多
关键词 高温氧化行为 纳米复合材料 SIO2纳米粒子 高温抗氧化性能 脉冲电沉积 CeO2 氧化时间 温度控制
下载PDF
CREEP BEHAVIORS OF Pt-RE ALLOYS AT HIGH TEMPERATURES 被引量:1
9
作者 Hu,Changyi Chen,Fusheng He,Huachun Institute of Precious Metals,Kunming 650221,China 《中国有色金属学会会刊:英文版》 CSCD 1993年第2期80-83,共4页
The creep behaviors of Pt-RE alloys have been studied at 1200℃ and 1400℃.The results show that asmall amount of RE elements improves the creep behaviors of platinum greatly.The creep behaviors of PtGd0.5,PtLa0.5 and... The creep behaviors of Pt-RE alloys have been studied at 1200℃ and 1400℃.The results show that asmall amount of RE elements improves the creep behaviors of platinum greatly.The creep behaviors of PtGd0.5,PtLa0.5 and PtLa0.3 Gd0.2,are best among all the alloys studied.As far as the creep behaviors are concerned,the traditional heat-resistance alloy PtGd10 can be replaced by PtGd0.5.Particularly,the properities of PtGd0.5are near to those of PtRb10.For most of the Pt-RE alloys,long-time,static,super high-temperature treatment inair is of no advantage to the creep rupture life.The mechanisms of the effects of rare-earths on high-temperaturecreep properties of platinum are discussed. 展开更多
关键词 Pt-RE ALLOYS high-temperature CREEP behaviorS
下载PDF
EFFECTS OF HIGH TEMPERATURE PRETREATMENTS ON HIGH TEMPERATURE FRACTURE BEHAVIOR OF SiC-C/SiC
10
作者 X.G.Luan L.F.Cheng +1 位作者 S.R.Qiao J.Zhang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第4期482-486,共5页
The samples made from a SiC-C/SiC composite were pretreated in AT under creep, fatigue, creep and fatigue interaction, as well as in dry oxygen and wet oxygen under fatigue at 1300℃for 15 hours. The fracture behavior... The samples made from a SiC-C/SiC composite were pretreated in AT under creep, fatigue, creep and fatigue interaction, as well as in dry oxygen and wet oxygen under fatigue at 1300℃for 15 hours. The fracture behaviors of the pretreated samples were investigated at 1300℃. The loading-strain curves and the microstructures of the sample were compared with each other. The various of high temperature tensile behaviors was attributed to the different microstructures resulted from different high temperature pretreatments. 展开更多
关键词 C/SIC high temperature tensile behavior FATIGUE CREEP
下载PDF
Effects of temperature on fracture behavior of Al-based in-situ composites reinforced with Mg_2Si and Si particles fabricated by centrifugal casting 被引量:5
11
作者 李波 王开 +3 位作者 刘明翔 薛寒松 朱子宗 刘昌明 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第4期923-930,共8页
An aluminum-based in-situ composites reinforced with Mg2Si and Si particles were produced by centrifugal casting A1-20Si-5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on ... An aluminum-based in-situ composites reinforced with Mg2Si and Si particles were produced by centrifugal casting A1-20Si-5Mg alloy. The microstructure of the composites was examined, and the effects of temperature on fracture behavior of the composite were investigated. The results show that the average fraction of primary Si and Mg2Si particles in the composites is as high as 38%, and ultimate tensile strengths (UTS) of the composites first increase then decrease with the increase of test temperature. Microstructures of broken specimens show that both the particle fracture and the interface debonding affect the fracture behavior of the composites, and the interface debonding becomes the dominant fracture mechanism with increasing test temperature. Comparative results indicate that rich particles in the composites and excellent interface strength play great roles in enhancing tensile property by preventing the movement of dislocations. 展开更多
关键词 aluminum based in-situ composites fracture behavior centrifugal casting high temperature
下载PDF
High temperature deformation behavior and optimization of hot compression process parameters in TC11 titanium alloy with coarse lamellar original microstructure 被引量:4
12
作者 鲁世强 李鑫 +2 位作者 王克鲁 董显娟 傅铭旺 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第2期353-360,共8页
The high temperature deformation behaviors of α+β type titanium alloy TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) with coarse lamellar starting microstructure were investigated based on the hot compression tests in the tem... The high temperature deformation behaviors of α+β type titanium alloy TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) with coarse lamellar starting microstructure were investigated based on the hot compression tests in the temperature range of 950-1100 ℃ and the strain rate range of 0.001-10 s-1. The processing maps at different strains were then constructed based on the dynamic materials model, and the hot compression process parameters and deformation mechanism were optimized and analyzed, respectively. The results show that the processing maps exhibit two domains with a high efficiency of power dissipation and a flow instability domain with a less efficiency of power dissipation. The types of domains were characterized by convergence and divergence of the efficiency of power dissipation, respectively. The convergent domain in a+fl phase field is at the temperature of 950-990 ℃ and the strain rate of 0.001-0.01 s^-1, which correspond to a better hot compression process window of α+β phase field. The peak of efficiency of power dissipation in α+β phase field is at 950 ℃ and 0.001 s 1, which correspond to the best hot compression process parameters of α+β phase field. The convergent domain in β phase field is at the temperature of 1020-1080 ℃ and the strain rate of 0.001-0.1 s^-l, which correspond to a better hot compression process window of β phase field. The peak of efficiency of power dissipation in ℃ phase field occurs at 1050 ℃ over the strain rates from 0.001 s^-1 to 0.01 s^-1, which correspond to the best hot compression process parameters of ,8 phase field. The divergence domain occurs at the strain rates above 0.5 s^-1 and in all the tested temperature range, which correspond to flow instability that is manifested as flow localization and indicated by the flow softening phenomenon in stress-- strain curves. The deformation mechanisms of the optimized hot compression process windows in a+β and β phase fields are identified to be spheroidizing and dynamic recrystallizing controlled by self-diffusion mechanism, respectively. The microstructure observation of the deformed specimens in different domains matches very well with the optimized results. 展开更多
关键词 titanium alloy coarse lamellar microstructure high temperature deformation behavior processing map hot compression process parameter optimization
下载PDF
High Temperature Tensile Property and Fracture Behavior of Directionally Solidified Fe-Al-Ta Eutectic Composites
13
作者 CUI Chunjuan DENG Li +5 位作者 LIU Wei WANG Yan LIU Yue LAI Yuanyuan SU Haijun LIU Yingying 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2022年第1期110-116,共7页
Fe-Al-Ta eutectic composites with solidification rates of 6,20,30,80 and 200μm/s were obtained by a modified Bridgman directional solidification technique and alloying.Moreover,tensile property and fracture behavior ... Fe-Al-Ta eutectic composites with solidification rates of 6,20,30,80 and 200μm/s were obtained by a modified Bridgman directional solidification technique and alloying.Moreover,tensile property and fracture behavior of Fe-Al-Ta eutectic composites were studied at 600℃.The relationship between mechanical property and microstructure at high temperature was studied.Microstructure of Fe-Al-Ta eutectic is composed of Fe_(2)Ta(Al)Laves phase and Fe(Al,Ta)matrix phase.In addition,the tensile strength at high temperatures is higher than that at room temperature.The tensile strength is increased with the increase of solidification rate.Moreover,fracture morphology transforms from cleavage fracture to dimple fracture as the solidification rate is increased at high temperatures. 展开更多
关键词 Fe-Al-Ta eutectic directional solidification high temperature tensile property fracture behavior
下载PDF
High-temperature oxidation behavior of a cast Ti-47.5Al-2.5V-1.0Cr-0.2Zr alloy
14
作者 Xue-jian Lin Hong-jun Huang +4 位作者 Xiao-guang Yuan Yin-xiao Wang Bo-wen Zheng Xiao-jiao Zuo Ge Zhou 《China Foundry》 SCIE CAS 2022年第5期443-454,共12页
The oxidation behavior of the Ti-47.5Al-2.5V-1.0Cr-0.2Zr alloy at 900℃ was investigated at different oxidation times(5,20,60 and 100 h).The results show that the total weight gain of the alloy after 100 h at 900℃ ox... The oxidation behavior of the Ti-47.5Al-2.5V-1.0Cr-0.2Zr alloy at 900℃ was investigated at different oxidation times(5,20,60 and 100 h).The results show that the total weight gain of the alloy after 100 h at 900℃ oxidation is 9.1 g·m^(-2),and the oxidation rate decreases with oxidation time.The oxides on the alloy surface are mainly TiO_(2) and Al_(2)O_(3).At the beginning of oxidation(5 h),the oxide film is relatively complete,thin,and the interface between the oxide layer and the matrix is virtually flat.At the end of oxidation(100 h),the thickness of the oxide film is expanded,cracking and spalling occur,and the spalling form is intra-film spalling.At the same time,oxygen is mainly distributed in the oxide film and the oxygen content in the alloy substrate is reduced,confirming that the TiAl alloy has a certain oxidation stability at 900℃.From the outer surface of the oxide layer to the matrix,the TiO_(2) content increases and the Al_(2)O_(3) content decreases.Oxidation proceeds to completion in this system via the dissolution and diffusion of O atom. 展开更多
关键词 cast TiAl alloy high temperature oxidation oxidation film oxidation behavior
下载PDF
High temperature mechanical behavior of alumina dispersion strengthened copper alloy with high content of alumina 被引量:6
15
作者 向紫琪 李周 +2 位作者 雷前 肖柱 庞咏 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期444-450,共7页
The microstructure and its effects on the high temperature mechanical behavior of Cu-2.7%Al_2O_3 (volume fraction) dispersion strengthened copper (ADSC) alloy were investigated. The results indicate that fine alum... The microstructure and its effects on the high temperature mechanical behavior of Cu-2.7%Al_2O_3 (volume fraction) dispersion strengthened copper (ADSC) alloy were investigated. The results indicate that fine alumina particles are uniformly distributed in the copper matrix, while a few coarse ones are distributed on the grain boundaries. Tensile tests results show that Hall-Petch mechanism is the main contribution to the yield strength of ADSC alloy at room temperature. Its high temperature strength is attributed to the strong pinning effects of alumina particles on the grain and sub-grain boundaries with dislocations. The ultimate tensile strength can reach 237 MPa and the corresponding yield strength reaches 226 MPa at 700℃. Tensile fracture morphology indicates that the ADSC alloy shows brittleness at elevated temperatures. Creep tests results demonstrate that the steady state creep rates at 400 ℃ are lower than those at 700 ℃. The stress exponents at 400 ℃ and 700℃ are 7 and 5, respectively, and the creep strain rates of the ADSC alloy are controlled by dislocation core diffusion and lattice diffusion. 展开更多
关键词 copper alloys alumina dispersion strengthened alloy high temperature mechanical behavior creep behavior FRACTURE strengthening mechanism
下载PDF
High temperature and high pressure rheological properties of high-density water-based drilling fluids for deep wells 被引量:10
16
作者 Wang Fuhua Tan Xuechao +3 位作者 Wang Ruihe Sun Mingbo Wang Li Liu Jianghua 《Petroleum Science》 SCIE CAS CSCD 2012年第3期354-362,共9页
To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines... To maintain tight control over rheological properties of high-density water-based drilling fluids, it is essential to understand the factors influencing the theology of water-based drilling fluids. This paper examines temperature effects on the rheological properties of two types of high-density water-based drilling fluids (fresh water-based and brine-based) under high temperature and high pressure (HTHP) with a Fann 50SL rheometer. On the basis of the water-based drilling fluid systems formulated in laboratory, this paper mainly describes the influences of different types and concentration of clay, the content of a colloid stabilizer named GHJ-1 and fluid density on the rheological parameters such as viscosity and shear stress. In addition, the effects of aging temperature and aging time of the drilling fluid on these parameters were also examined. Clay content and proportions for different densities of brine-based fluids were recommended to effectively regulate the rheological properties. Four theological models, the Bingham, power law, Casson and H-B models, were employed to fit the rheological parameters. It turns out that the H-B model was the best one to describe the rheological properties of the high-density drilling fluid under HTHP conditions and power law model produced the worst fit. In addition, a new mathematical model that describes the apparent viscosity as a function of temperature and pressure was established and has been applied on site. 展开更多
关键词 high-density water-based drilling fluid rheological behavior CLAY high temperature high pressure linear fitting rheological model mathematical model
下载PDF
Effects of high temperature on the microstructure and mechanical behavior of hard coal 被引量:12
17
作者 Chengdong Su Jiadong Qiu +1 位作者 Qiuhong Wu Lei Weng 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2020年第5期643-650,共8页
Coal is a common porous sedimentary rock whose microstructure and mechanical behavior are often affected by high temperature.In order to deeply investigate the effect of high temperature on the structure and mechanica... Coal is a common porous sedimentary rock whose microstructure and mechanical behavior are often affected by high temperature.In order to deeply investigate the effect of high temperature on the structure and mechanical properties of coal,six groups of coal samples with different heating temperatures were prepared.Various testing methods,including ultrasonic test,scanning electron microscopy,nuclear magnetic resonance and uniaxial compression test,were used in this study.The results showed that the physical and chemical change processes of coal samples under high temperature can be divided into two stages:the stage of drying and degassing and the stage of pyrolysis of the coal matrix.With the increase of heating temperature,the total porosity of coal samples increases,while the integrity and the deformation resistance of coal samples decrease.In addition,the elastic modulus and uniaxial compressive strength of the coal sample decrease with the increase of heating temperature.The Poisson’s ratio decreases firstly and then increases with the increase of heating temperature. 展开更多
关键词 high temperature COAL MICROSTRUCTURE Mechanical behavior Nuclear magnetic resonance
下载PDF
Future Changes in Extreme High Temperature over China at 1.5℃-5℃ Global Warming Based on CMIP6 Simulations 被引量:12
18
作者 Guwei ZHANG Gang ZENG +1 位作者 Xiaoye YANG Zhihong JIANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第2期253-267,共15页
Extreme high temperature(EHT)events are among the most impact-related consequences related to climate change,especially for China,a nation with a large population that is vulnerable to the climate warming.Based on the... Extreme high temperature(EHT)events are among the most impact-related consequences related to climate change,especially for China,a nation with a large population that is vulnerable to the climate warming.Based on the latest Coupled Model Intercomparison Project Phase 6(CMIP6),this study assesses future EHT changes across China at five specific global warming thresholds(1.5℃-5℃).The results indicate that global mean temperature will increase by 1.5℃/2℃ before 2030/2050 relative to pre-industrial levels(1861-1900)under three future scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5),and warming will occur faster under SSP5-8.5 compared to SSP1-2.6 and SSP2-4.5.Under SSP5-8.5,global warming will eventually exceed 5℃ by 2100,while under SSP1-2.6,it will stabilize around 2℃ after 2050.In China,most of the areas where warming exceeds global average levels will be located in Tibet and northern China(Northwest China,North China and Northeast China),covering 50%-70%of the country.Furthermore,about 0.19-0.44 billion people(accounting for 16%-41%of the national population)will experience warming above the global average.Compared to present-day(1995-2014),the warmest day(TXx)will increase most notably in northern China,while the number of warm days(TX90p)and warm spell duration indicator(WSDI)will increase most profoundly in southern China.For example,relative to the present-day,TXx will increase by 1℃-5℃ in northern China,and TX90p(WSDI)will increase by 25-150(10-80)days in southern China at 1.5℃-5℃ global warming.Compared to 2℃-5℃,limiting global warming to 1.5℃ will help avoid about 36%-87%of the EHT increases in China. 展开更多
关键词 extreme high temperature China CMIP6 1.5℃-5℃global warming
下载PDF
High temperature tribological behaviors of aluminum matrix composites reinforced with solid lubricant particles 被引量:5
19
作者 V.V.MONIKANDAN P.K.RAJENDRAKUMAR M.A.JOSEPH 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第5期1195-1210,共16页
The AA6061-10 wt.%B4 C mono composite, AA6061-10 wt.%B4 C-Gr(Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10 wt.%B4 C-Mo S2 hybrid composites containing 2.5, 5, and 7.5 wt.%... The AA6061-10 wt.%B4 C mono composite, AA6061-10 wt.%B4 C-Gr(Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10 wt.%B4 C-Mo S2 hybrid composites containing 2.5, 5, and 7.5 wt.% Mo S2 particles were fabricated through stir casting. The dry sliding tribological behaviors of the mono composite and hybrid composites were studied as a function of temperature on high temperature pin-on-disc tribotester against EN 31 counterface. The wear rate and friction coefficient of the Gr-reinforced and Mo S2-reinforced hybrid composites decreased in the temperature range of 30-100 ℃ due to the combined lubrication offered by the wear protective layer and its solid lubricant phase. Scanning electron microscopy(SEM) observation of the worn pin surface revealed severe adhesion, delamination, and abrasion wear mechanisms at temperatures of 150, 200, and 250 ℃, respectively. At 150 ℃, transmission electron microscopy(TEM) observation of the hybrid composites revealed the formation of deformation bands due to severe plastic deformation and fine crystalline structure due to dynamic recrystallization. 展开更多
关键词 aluminum hybrid composites high temperature tribological behavior solid lubrication deformation band dynamic recrystallization
下载PDF
Interfacial Behavior of Sulfur and Yttrium in Yttrium Modified Ni _3Al Based Alloy IC6 during High Temperature Oxidation Process 被引量:2
20
作者 肖程波 韩雅芳 《Journal of Rare Earths》 SCIE EI CAS CSCD 2000年第2期124-127,共4页
The interfacial behavior of sulfur and yttrium in the yttrium modified Ni 3Al based alloy IC6 during oxidation at 1100 ℃ was analyzed by X ray line scan of electron probe microstructural analysis(EPMA). The resul... The interfacial behavior of sulfur and yttrium in the yttrium modified Ni 3Al based alloy IC6 during oxidation at 1100 ℃ was analyzed by X ray line scan of electron probe microstructural analysis(EPMA). The results show that the migration and segregation of sulfur to the interface between oxide scale and the substrate at high temperature is retarded owing to the presence of yttrium. This is attributed to the desulfurization by yttrium in the melt and the trapping of sulfur by yttrium rich phases during oxidation, which leads to improving the coherence between oxide scale and substrate. Another reason of increasing the high temperature oxidation resistance of alloy IC6 by the addition of yttrium is that yttrium migrates to the grain boundaries of oxides during oxidation and hence improve their strength. This results in the transformation of the oxide scale spallation cracks from intergranular cracks for alloy without yttrium to transgranular ones for yttrium modified alloy. 展开更多
关键词 rare earths SULFUR YTTRIUM Ni 3Al high temperature oxidation interfacial behavior
下载PDF
上一页 1 2 32 下一页 到第
使用帮助 返回顶部