A glass frit containing Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa_(2)O_(6)ceramics in this stud...A glass frit containing Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa_(2)O_(6)ceramics in this study.The good low-firing effects are presented due to the high matching relevance between Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass and MgTa_(2)O_(6)ceramics.The pure tri-rutile MgTa_(2)O_(6)structure remains unchanged,and high sintering compactness can also be achieved at 1150℃.We found that the Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass not only greatly improves the low-temperature sintering characteristics of MgTa_(2)O_(6)ceramics but also maintains a high(quality factor(Q)×resonance frequency(f))value while still improving the temperature stability.Typically,great microwave dielectric characteristics when added with 2wt%Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass can be achieved at 1150℃:dielectric constant,ε_(r)=26.1;Q×f=34267 GHz;temperature coefficient of resonance frequency,τ_(f)=-8.7×10^(-6)/℃.展开更多
This study considered the role of coal as China’s basic energy source and examines the development of the coal industry.We focused on the intelligent development of coal mines,and introduced the“Chinese mode”of int...This study considered the role of coal as China’s basic energy source and examines the development of the coal industry.We focused on the intelligent development of coal mines,and introduced the“Chinese mode”of intelligent mining in underground coal mines,which uses complete sets of technical equipment to propose classifcation and grading standards.In view of the basic characteristics and technical requirements of intelligent coal mine systems,we established a digital logic model and propose an information entity and knowledge map construction method.This involves an active information push strategy based on a knowledge demand model and an intelligent portfolio modeling and distribution method for collaborative control of coal mines.The top-level architecture of 5G+intelligent coal mine systems combines intelligent applications such as autonomous intelligent mining,human–machine collaborative rapid tunneling,unmanned auxiliary transportation,closed-loop safety control,lean collaborative operation,and intelligent ecology.Progress in intelligent mining technology was described in terms of a dynamic modifed geological model,underground 5G network and positioning technology,intelligent control of the mining height and straightness of the longwall working face,and intelligent mining equipment.The development of intelligent coal mines was analyzed in terms of its imbalances,bottlenecks,and the compatibility of large-scale systems.Implementation ideas for promoting the development of intelligent coal mines were proposed,such as establishing construction standards and technical specifcations,implementing classifcation and grading standards according to mining policy,accelerating key technology research,and building a new management and control model.展开更多
A plasma jet ignition technology was studied for aeroengine combustor.The advantages of compact stnucture and advanced performance of air-cooled plasma jet igniter had been tested and verified in the opening test.The ...A plasma jet ignition technology was studied for aeroengine combustor.The advantages of compact stnucture and advanced performance of air-cooled plasma jet igniter had been tested and verified in the opening test.The plasma jet igniter could produce a continuous plasma jet,stable and reliable ignition.The influence factors of plasma jet ignition aerodynamic and structure were studied in the opening test.Continuous plasma jet was closely related to inlet pressure and flow,simultaneously to the igniter nozzle geometry and throat size.Based on the stable continuous plasma jet,some methods were explored in order to reduce plasma output power,optimize the structure design,and improve the thermal protective.The plasma jet igniter applied to aeroengine combustor was identified initially.For combustion chamber with the igniter,altitude ignition performance were experimented for the inlet pressure of plasma ignition from 10 kPa to 50 kPa,the flow of plasma jet not more than 0.20 g/s,and energy output of ignition from 800 W to 1500 W.The test results were compared with that of conventional aeroengine high energy ignition system.The results show that the plasma jet igniter is better than the conventional one.展开更多
Polycrystalline Cr2AlC coatings were prepared on M38G superalloy using a two-step method consisting of magnetron sputtering from Cr-Al-C composite targets at room temperature and subsequent annealing at 620 ℃. Partic...Polycrystalline Cr2AlC coatings were prepared on M38G superalloy using a two-step method consisting of magnetron sputtering from Cr-Al-C composite targets at room temperature and subsequent annealing at 620 ℃. Particularly, various targets synthesized by hot pressing mixture of Cr, Al, and C powders at 650-1000 ℃ were used. It was found that regardless of the phase compositions and density of the com- posite targets, when the molar ratio of Cr:Al:C in the starting materials was 2:1:1, phase-pure crystalline Cr2AlC coatings were prepared by magnetron sputtering and post crystallization. The Cr2AIC coatings were dense and crack-free and had a duplex structure. The adhesion strength of the coating deposited on M38G superalloy from the 800 ℃ hot-pressed target and then annealed at 620 ℃ for 20 h in Ar exceeded 82 ± 6 MPa, while its hardness was 12 ± 3 GPa.展开更多
基金This study is supported by the National Key Research and Development Program of China(No.2022YFB2807405)the Qinchuangyuan Citing High-level Innovation and Entrepreneurship Talent Projects(No.QCYRCXM-2022-40)+2 种基金the National Natural Science Foundation of China(Nos.U2341263 and 62371366)Open project of Yunnan Precious Metals Laboratory Co.,Ltd(No.YPML-2023050246)Innovation Capability Support Program of Shaanxi,China(Nos.2023-CX-PT-30 and 2022TD-28).
文摘A glass frit containing Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa_(2)O_(6)ceramics in this study.The good low-firing effects are presented due to the high matching relevance between Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass and MgTa_(2)O_(6)ceramics.The pure tri-rutile MgTa_(2)O_(6)structure remains unchanged,and high sintering compactness can also be achieved at 1150℃.We found that the Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass not only greatly improves the low-temperature sintering characteristics of MgTa_(2)O_(6)ceramics but also maintains a high(quality factor(Q)×resonance frequency(f))value while still improving the temperature stability.Typically,great microwave dielectric characteristics when added with 2wt%Li_(2)O-MgO-ZnO-B_(2)O_(3)-SiO_(2)glass can be achieved at 1150℃:dielectric constant,ε_(r)=26.1;Q×f=34267 GHz;temperature coefficient of resonance frequency,τ_(f)=-8.7×10^(-6)/℃.
基金supported by the National Natural Science Foundation of China(Grant Numbers 51834006 and 51874174).
文摘This study considered the role of coal as China’s basic energy source and examines the development of the coal industry.We focused on the intelligent development of coal mines,and introduced the“Chinese mode”of intelligent mining in underground coal mines,which uses complete sets of technical equipment to propose classifcation and grading standards.In view of the basic characteristics and technical requirements of intelligent coal mine systems,we established a digital logic model and propose an information entity and knowledge map construction method.This involves an active information push strategy based on a knowledge demand model and an intelligent portfolio modeling and distribution method for collaborative control of coal mines.The top-level architecture of 5G+intelligent coal mine systems combines intelligent applications such as autonomous intelligent mining,human–machine collaborative rapid tunneling,unmanned auxiliary transportation,closed-loop safety control,lean collaborative operation,and intelligent ecology.Progress in intelligent mining technology was described in terms of a dynamic modifed geological model,underground 5G network and positioning technology,intelligent control of the mining height and straightness of the longwall working face,and intelligent mining equipment.The development of intelligent coal mines was analyzed in terms of its imbalances,bottlenecks,and the compatibility of large-scale systems.Implementation ideas for promoting the development of intelligent coal mines were proposed,such as establishing construction standards and technical specifcations,implementing classifcation and grading standards according to mining policy,accelerating key technology research,and building a new management and control model.
基金The study is all supported by Aviation Science Foundation of Aviation Industry Corporation of Chinathe authors are grateful to the participants of Shenyang Engine Research Institute of China for their help.
文摘A plasma jet ignition technology was studied for aeroengine combustor.The advantages of compact stnucture and advanced performance of air-cooled plasma jet igniter had been tested and verified in the opening test.The plasma jet igniter could produce a continuous plasma jet,stable and reliable ignition.The influence factors of plasma jet ignition aerodynamic and structure were studied in the opening test.Continuous plasma jet was closely related to inlet pressure and flow,simultaneously to the igniter nozzle geometry and throat size.Based on the stable continuous plasma jet,some methods were explored in order to reduce plasma output power,optimize the structure design,and improve the thermal protective.The plasma jet igniter applied to aeroengine combustor was identified initially.For combustion chamber with the igniter,altitude ignition performance were experimented for the inlet pressure of plasma ignition from 10 kPa to 50 kPa,the flow of plasma jet not more than 0.20 g/s,and energy output of ignition from 800 W to 1500 W.The test results were compared with that of conventional aeroengine high energy ignition system.The results show that the plasma jet igniter is better than the conventional one.
基金supported by the National Natural Science Foundation of China under Grant Nos.51271191,51571205 and 51401209
文摘Polycrystalline Cr2AlC coatings were prepared on M38G superalloy using a two-step method consisting of magnetron sputtering from Cr-Al-C composite targets at room temperature and subsequent annealing at 620 ℃. Particularly, various targets synthesized by hot pressing mixture of Cr, Al, and C powders at 650-1000 ℃ were used. It was found that regardless of the phase compositions and density of the com- posite targets, when the molar ratio of Cr:Al:C in the starting materials was 2:1:1, phase-pure crystalline Cr2AlC coatings were prepared by magnetron sputtering and post crystallization. The Cr2AIC coatings were dense and crack-free and had a duplex structure. The adhesion strength of the coating deposited on M38G superalloy from the 800 ℃ hot-pressed target and then annealed at 620 ℃ for 20 h in Ar exceeded 82 ± 6 MPa, while its hardness was 12 ± 3 GPa.