检索结果-南通市图书馆

Fe:ZnSe laser pumped by a 2.93-μm cr, Er:YAG laser

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第6期28卷 195-198页

作者： Ying-Yi Li Tong-Yu Dai Xiao-Ming Duan Chun-Fa Guo Li-Wei Xu You-Lun Ju National Key Laboratory of Tunable Laser Technology Harbin Institute of TechnologyHarbin 150001China

We demonstrated an Fe:ZnSe laser pumped by a 2.93-μm cr, Er:YAG laser at liquid nitrogen and room temperature in single-shot free-running operation for the first time. The xenon flash lamp pumped cr, Er:YAG laser had a maximum single pulse energy of 1.414 J, and the threshold and slope efficiency were 141.70 J and 0.70% which were respectively reduced by 29.3% and increased by 52.2% compared with the Er:YAG laser. At liquid nitrogen temperature of 77 K, the maximum single pulse energy of the Fe:ZnSe laser was 197.6 m J, corresponding to a slope efficiency of 13.4%. The central wavelength and full width at half maximum(FWHM) linewidth were 4037.4 nm and 122.0 nm, respectively. At room temperature, the laser generated a maximum single pulse energy of 3.5 mJ at the central wavelength of 4509.6 nm with an FWHM linewidth of 171.5 nm.

关键词： Fe:ZnSe cr Er:YAG free-running

Effect of cr content and cooling rate on the primary phase of Al-2.5Mn alloy

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2019年第12期26卷 1551-1558页

作者： Hang-qi Feng Zhi-bo Yang Ye-tong Bai Li Zhang Yu-lin Liu School of Materials Science and Engineering Shenyang Aerospace University

The effect of cr content and cooling rate on the microstructure of Al-Mn alloy was studied using well resistance furnace melting,and the alloy was analyzed using scanning electron microscopy(SEM)and X-ray diffraction(XRD).The experimental results showed that adding cr could significantly improve the morphology of the primary phase in the Al-2.5Mn *** cr,the primary phase in the alloy was thick,needle-like,and strip-like *** adding 0.2wt%-0.5wt%cr,the primary phase in the upper part of the alloy was gradually fined and reached the best effect at 0.35wt%*** the content of cr was 0.5wt%,the microstructure of the primary phase in the upper part began to *** bottom of the alloy was a large bulk phase,but still much finer than that without adding *** and SEM analysis showed that the precipitation phase at the bottom was mainly Al85Mn7cr8,while the fine microstructure at the top was Al6Mn and *** results of the cooling rate experiments showed that the primary phase of Al-2.5Mn-0.35cr was further refined,and the eutectic microstructure was partly achieved,under air-cooling *** when the cooling method was iron die-cooling,the microstructure of the Al-2.5Mn-0.35cr alloy was changed into a eutectic microstructure.

关键词： Al-2.5Mn alloy cr content primary phase cooling rate

Spectroscopic investigations of Gd_3Sc_2Ga_3O_(12) garnet doped with cr^(3+) and Nd^(3+) ions

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2009年第4期27卷 560-563页

作者： K.Lemański P.J.Dereń A.Gagor W.Strek Institute of Low Temperatures and Structure Research Polish Academy of Sciences

Absorption, excitation and emission spectra as well as decay time measurements at 10, 77, and 300 K were perfumed for Gd3Sc2Ga3O12 garnet single-crystal doped with cr^3＋ and Nd^3＋ ions. Strong reabsorption of cr3＋ emission by Nd3＋ absorption lines was ob- served. The assignments of f-f and d-d transitions were proposed. The broad emission band of chromium ions is an indication that weak/intermediate crystal field strength is present at the cr3＋ site.

关键词： Gd3Sc2Ga3O12 crystal reabsorption cr Nd rare earths

Shape Memory Effect of As-aged Fe-14Mn-5Si-8cr-4Ni-0.2C Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2000年第4期16卷 424-426页

作者： Yuhua WEN, Ning LI and Mingjing TU (Department of Materials Shaping and Controlling Engineering, Sichuan University, Chengdu 610065, China) Department of Materials Shaping and Controlling Engineering Sichuan University Chengdu 610065 China

The effects of aging temperature on shape memory effect, mechanical properties and microstruc-ture of Fe-14Mn-5Si-8cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.

关键词： Mn Shape Memory Effect of As-aged Fe-14Mn-5Si-8cr-4Ni-0.2C Alloy As Fe cr Ni Si

Forming Mechanism of Gaseous Defect in Ti-48Al-2cr-2Nb Exhaust Valves Formed with Permanent Mold Centrifugal Casting Method

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2001年第5期17卷 569-571页

作者： Research Notes Wenbin SHENG, Jingjie GUO, Yanqing SU, Hongsheng DING and Jun JIA School of Materials Science and Engineering, Harbin Institute of Technology. Harbin 150001, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

A method combining theoretical analysis with experiment is adopted and the flowing process of Ti-48A1-2cr-2Nb alloy melt poured in a permanent mould during the centrifugal casting process has been analyzed. A mathematical model of the filling process is established and the forming mechanism of internal gaseous defect is summarized. The results of calculation show that the melt fills the mould with varying cross-section area and inclined angle. The filling speed of the cross-section is a function of filling time. The cross-section area is directly proportional to the filling speed and the inclined angle is inversely proportional to the filling speed at a given rotating speed of the platform. Both of them changes more obvious near the mould entrance. The gaseous defect can be formed in several ways and the centrifugal field has an important influence on the formation of the defect. In addition, the filling process in centrifugal field has been verified by wax experiments and the theoretical analysis are consistent with experimental results.

关键词： Forming Mechanism of Gaseous Defect in Ti-48Al-2cr-2Nb Exhaust Valves Formed with Permanent Mold Centrifugal Casting Method Mold Ti Al cr

Behavior of Zr-Rich Phase in a Cast NiAl-33.5cr-0.5Zr Alloy during Heat Treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2001年第6期17卷 629-632页

作者： Hui LI, sJianting GUQ, Wanhui LAI and Shuhe WANG Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China [Manuscript received July 7, 2000, in revised form October 11, 2000] Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

There are many Zr particles in as-cast NiAl-33.5cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic of beta -NiAl and cx-cr. After air and furnace cooling solution treatments, far 1400 degreesC, 2 h and 1450 degreesC, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. During solution treatment at 1450 degreesC, bulk and 'fish bone' shape Zr-rich phases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2AlZr phase forms after 1450 C for 1h F.C. and 850 degreesC for 12 h, F.C.. The alloy has less pure Zr and Ni2AlZr phase after 1400 degreesC with both air and furnace cooling followed by 850 C and 950 C for 12 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAlZr and a phase enriched Zr and cr forms at the edge of the eutectic of beta -NiAl and alpha -cr in the alloy treated at 1400 degreesC, 2 h, F.C. and 950 degreesC, 12 h, F.C.

关键词： NiAl Zr Behavior of Zr-Rich Phase in a Cast NiAl-33.5cr-0.5Zr Alloy during Heat Treatment cr Cast

Factors Affecting Transformation Temperatures in Fe-Mn-Si-cr-Ni Shape Memory Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2000年第5期16卷 537-539页

作者： Yuhua WEN+, ding LI and Mingjing TU (Department of Materials Shaping and Controlling Engineering, Sichuan University, Chengdu 610065, China) Department of Materials Shaping and Controlling Engineering Sichuan University Chengdu 610065 China

The effects of prestrain and annealing temperature on phase transformation temperatures in Fel4Mn5Si8cr4Ni shape memory alloy have been studied. The results showed that when the annealing temperature was 673 K, both the At and the Ms temperatures increased appreciably as the prestrain increased, the As temperature increased slightly with increasing prestrain; the resistivity difference at 303 K between the heating and cooling curve also increased with increasing prestrain, which agreed with the recovery strain. The shape memory effect in Fe-Mn-Si-cr-Ni shape memory alloy is caused by the stress-induced γ→ε martensite transformation and its reverse transformation. When the prestrain was 10%, the Ms temperature decreased remarkably as the annealing temperature increased.

关键词： Factors Affecting Transformation Temperatures in Fe-Mn-Si-cr-Ni Shape Memory Alloy Fe Mn cr Ni Si

Wear and corrosion resistance of laser remelted and plasma sprayed Ni and cr coatings on copper

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2004年第5期14卷 885-889页

作者：梁工英黄俊达安耿 Department of Materials Physics Science School Xi'an Jiaotong University Xi'an 710049 China Department of Mechanical Engineering The Hong Kong Polytechnic University Hong Kong China

Nickel and chromium coatings were produced on the copper sheet using plasma spraying and laser remelting. The sliding wear test was achieved on a block-on-ring tester and the corrosion test was carried out in an acidic atmosphere. The corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. The experimental results show that the nickel and chromium coatings display better wear resistance and corrosion resistance relative to the original pure copper sample. The wear resistance of the coatings is 812 times as large as original samples, and the wear resistance of laser remelted samples is better than that of plasma sprayed ones. The corrosion resistance of laser remelted nickel and chromium samples is better than that of plasma sprayed samples respectively. The corrosion rate of chromium coatings is less than that of nickel coatings, and the laser remelted cr coating exhibits the least corrosion rate.

关键词：等离子喷涂工艺激光技术铜涂层 cr Ni 耐腐蚀性

Radiation Losses in the Microwave X Band in Al-cr Substituted Y-Type Hexaferrites

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2017年第4期34卷 35-38页

作者： D.Basandrai R.K.Bedi A.Dhami J.Sharma S.B.Narang K.Pubby A.K.Srivastava Research Scholar Department of Physics I. K. Gujral Punjab Technical University Jalandhar India Department of Physics Lovely Professional University Phagwara India principal Satyam Institute of Engineering & Technology Amritsar India Department of Electronic Technology Guru Nanak Dev University Amritsar India

We present a study on radiation losses in the microwave X band in Al-cr substituted Y-type hexaferrites, namely Ba2Mg2Alx/2crx/2Fe12-xO22 （x = 0, 0.5 and 1.0）. The study is performed by means of a vector network analyzer, Fourier transform infrared spectroscopy, a vibrating sample magnetometer and x-ray powder diffraction. Ba2Mg2Fe12O22 hexaferrite shows radiation loss of -37.25dB （99.999% loss） at frequency 9.81 GHz, which can be attributed to its high value of saturation magnetization, i.e., 22.08emu/g. Moreover, we obtain that magnetic properties have strong influence on the radiation losses.

关键词： Ba Al Radiation Losses in the Microwave X Band in Al-cr Substituted Y-Type Hexaferrites cr