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Rare Metals 2017年第11期36卷 872-877页

作者： Hui-Bin Xu Song Tang Hai-Feng Xi Peng-Yu Gao Mo-Yang Li School of Materials Science and Engineering Chongqing University of Technology State Key Laboratory of Advance Welding and Joining Harbin Institute of Technology

In this study, 5052 steel were joined by a new way aluminum alloy and Q235 of arc milling brazing, with the Zn15%A1 filler metal and no use of flux. Effect of rotation speed on mechanical properties and microstructure of joint interface was investigated. The results show that increasing rotation speed is in favor of formation of weld and spread of filler metal on substrate. The fine grain with homogeneous composition in brazed seam can be realized by the stronger stirring in pool induced by milling at more higher rotation speed. And, a composite joint reinforced with needle-like or block-like Fe-A1-Zn intermetallic compounds （IMCs） particle can be obtained by arc milling brazing, which comes from the reaction between steel scrape and Zn-A1 filler alloy. The test on strength of joint interface shows that with the increase in rotation speed, there is a peak value in variation ranges of strength of joint interface. This is to say, when rotation speed is 2720 ***-~, the strength of joint has maximum value （182.01 MPa）. Moreover, a thin and discontinuous IMCs layer at joint interface can be obtained by increasing rotation speed. But at a low or high rotation speed, there also is a crack at joint interface, which weakens the strength of joint interface. Only at 2720 ***-1, a good joint interface without an obvious crack can be realized.

关键词： Dissimilar materials Intermetallic compounds rotation speed Arc brazing Milling

Distribution of oxide inclusions in H13 castings under super-gravity field with multi-stage rotation speeds

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Journal of Iron and Steel Research International 2024年第1期31卷 121-133页

作者： Shao-ying Li Xiao-jun Xi Xing-ming Zhao Han-jie Guo Jing Guo School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing100083China Beijing Key Laboratory of Special Melting and Preparation of High-End Metal Materials Beijing100083China Beijing Beiye Functional Materials Corporation Beijing100192China Shandong Tianwu Forming Technology Co. Ltd.Liaocheng252024ShandongChina

The 42 kg industrial H13 castings were prepared by different super-gravity fields with multi-rotation speeds,and the distribution of oxide inclusions in the castings was *** addition,the inward movement Reynolds number and inward movement time of oxide inclusions as well as the solidification time of molten steel at different positions in the castings were calculated to clarify the removal mechanism of oxide inclusions in super-gravity *** results show that the large size(i.e.,greater than 10μm)oxide inclusions are mainly concentrated in the inner and outer parts of the super-gravity castings with constant rotation speed(500 r min^(-1))and five-stage rotation speeds(500,600,750,850,and 950 r min^(-1)),respectively,while there are no large oxide inclusions in the super-gravity castings with three-stage rotation speeds(500,600,and 750 r min^(-1)).Although an increase in the particle size of inclusion and the rotation speed in super-gravity field is conducive to the increase in the inward movement Reynolds number of oxide inclusions and reduction in the inward movement time of oxide inclusions,it will reduce the local solidification time of molten *** the range of the rotation speed studied,the super-gravity field with three-stage rotation speeds has the best effect on the removal of inclusions in H13 molten steel.

关键词： Distribution Oxide inclusion H13 casting Super-gravity field rotation speed

Optimum traveling and rotation speeds in friction stir welding for dissimilar Al alloys

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Transactions of Nonferrous Metals Society of China 2011年第7期21卷 1486-1490页

作者： Jae-Cheul PARK Min-Su HAN Seok-Ki JANG Seong-Jong KIM Division of Marine System Engineering Mokpo Maritime UniversityMokpo CityJeonnam530-729Korea

Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding of 5052-O and 6061-T6 Al alloys were *** optimum traveling and rotation speeds were identified to be 61mm/min and 1600r/min using various mechanical characteristic evaluation methods.

关键词： Al alloy friction stir welding (FSW) traveling speed rotation speed mechanical property

Experimental Study of Cavitation Phenomenon in a Centrifugal Blood Pump Induced by the Failure of Inlet Cannula

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Chinese Journal of Mechanical Engineering 2014年第1期27卷 165-170页

作者： LIN Zhe RUAN Xiaodong ZOU Jun FU Xin The State Key Lab of Fluid Power Transmission and Control Zhejiang University

Cavitation of centrifugal blood pump is a serious problem accompany with the blocking failure of short inlet cannula. However, hardly any work has been seen in published literature on this complex cavitation phenomenon caused by the coupling effect of inlet cannula blocking and pumps suction. Even for cavitation studies on ordinary centrifugal pumps, similar researches on this issue are rare. In this paper, the roles of throttling, rotation speed and fluid viscosity on bubble inception and intensity in a centrifugal blood pump are studied, on the basis of experimental observations. An adjustable throttle valve installed just upstream blood pump inlet is used to simulate the throttling effect of the narrowed inlet cannula. The rotation speed is adjusted from 2 600 r/rain to 3 200 r/min. Glycerin water solutions are used to investigate the influences of kinetic viscosity. Bubbles are recorded with a high-speed video camera. Direct observation shows that different from cavitation in industrial centrifugal pumps, gas nuclei appears at the nearby of vane leading edges while throttling is light, then moves upstream to the joint position of inlet pipe and pump with the closing of the valve. It＇s found that the critical inlet pressure, obtained when bubbles are first observed, decreases linearly with viscosity and the slope is independent with rotation speeds; the critical inlet pressure and the inlet extreme pressure which is obtained when the throttle valve is nearly closed, fall linearly with rotation speed respectively and the relative pressure between them is independent with rotation speed and fluid viscosity. This paper studies experimentally on cavitation in centrifugal blood pump that caused by the failure of assembled short inlet cannula, which mav beneficial the desima of centrifugal blood Dumo with inlet cannula.

关键词： centrifugal blood pump cavitation viscosity cannula diameter rotation speed

Calculation method for the formation time of dynamic filter cake in slurry shield tunneling

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Frontiers of Structural and Civil Engineering 2024年第9期18卷 1337-1349页

作者： Yinzun YANG Dajun YUAN Changyan DU Dalong JIN Jun HAO Key Laboratory of the Ministry of Education for Urban Underground Engineering Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China China Railway 14th Bureau Group Mega Shield Engineering Co. Ltd.Nanjing 211800China

In slurry shield tunneling,the stability of tunnel face is closely related to the filter *** cutting of the cutterhead has negative impact on the formation of filter *** study focuses on the formation time of dynamic filter cake considering the filtration effect and rotation of *** effect is the key factor for slurry infiltration.A multilayer slurry infiltration experiment system is designed to investigate the variation of filtrate rheological property in infiltration *** mass concentration C_(L),soil permeability coefficient k,the particle diameter ratio between soil equivalent grain size and representative diameter of slurry particles d_(10)/D_(85) are selected as independent design variables to fit the computational formula of filtration *** on the relative relation between the mass of deposited particles in soil pores and infiltration time,a mathematical model for calculating the formation time of dynamic filter cake is proposed by combining the formation criteria and formation rate of external filter *** accuracy of the proposed model is verified through existing experiment *** results show that filtration coefficient is positively correlated with slurry mass concentration,while negatively correlated with the soil permeability coefficient and the particle diameter ratio between soil and *** infiltration distance increases,the adsorption capacity of soil skeleton to slurry particles gradually *** formation time of external filter cake is significantly lower than internal filter cake and the ratio is approximately *** the dynamic cutting of the cutterhead,the formation time is positively associated with the rotation speed of cutter head,while negatively with the phase angle difference between adjacent cutter *** formation rate of external filter cake is greater than 98%when d_(10)/D_(85)≤*** increasing the content or decreasing the diameter size of solid-phase

关键词： slurry infiltration filtration coefficient dynamic filter cake formation time rotation speed phase angle

Pitting Corrosion Behavior of Stainless Steel 304 in Carbon Dioxide Environments

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Journal of Iron and Steel Research International 2004年第4期11卷 47-51页

作者： LI Guo-min GUO Xing-peng ZHENG Jia-shen Huazhong University of Science and Technology

With a rotating cylinder electrode apparatus, the polarization behaviors of the mild steel and the stainless steel 0Cr18Ni9 in NaHCO 3 (0.5 M)+Na 2CO 3 (0.5 M) solution with and without erodent particles were investigated and compared. The results show that the rotation speed of cylinder hardly affects the polarization behavior of sample in solution without particles but exerts a great influence on that with particles. Increasing rotation speed, the free corrosion potential shifts to positive direction and the oxygen limiting current density increases. Both the mild steel and stainless steel 0Cr18Ni9 experience a significant increase of the mass loss by increasing erosion, and erosive wear was dominated by severe micro-plowing. The insufficient mechanical strength of both materials leads to a low resistance to particle removal. Increasing peripheral velocities of the rotating cylinder enhances the corrosion rate of the mild steel. The stainless steel 0Cr18Ni9, due to a high erosive wear, also suffers from similar erosion-corrosion damage, despite that its corrosion resistance is much higher than that of the mild steel.

关键词： steel erosion corrosion polarization behavior rotation speed

Erosion and Corrosion of Mild Steel and Stainless Steel in Sodium Carbonate/Bicarbonate Solution Bearing Alumina Particle

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Journal of Iron and Steel Research International 2004年第4期11卷 52-55页

作者： YUAN Qing-long LIANG Hong-da Taiyuan University of Technology

With a rotating cylinder electrode apparatus,the polarization behaviors of the mild steel and the stainless steel 0Cr18Ni9 in NaHCO3(0.5M)+Na2CO3(0.5M)solution with and without erodent particles were investigated and *** results show that the rotation speed of cylinder hardly affects the polarization behavior of sample in solution without particles but exerts a great influence on that with *** rotation speed,the free corrosion potential shifts to positive direction and the oxygen limiting current density *** the mild steel and stainless steel 0Cr18Ni9 experience a significant increase of the mass loss by increasing erosion,and erosive wear was dominated by severe *** insufficient mechanical strength of both materials leads to a low resistance to particle *** peripheral velocities of the rotating cylinder enhances the corrosion rate of the mild *** stainless steel 0Cr18Ni9,due to a high erosive wear,also suffers from similar erosion-corrosion damage,despite that its corrosion resistance is much higher than that of the mild steel.

关键词： steel erosion corrosion polarization behavior rotation speed

Design of Tracking Loop for Single Antenna Satellite Navigation Receivers under the Situation of rotation

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Design of Tracking Loop for Single Antenna Satellite Navigat...