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Experimental rigs for testing components of advanced industrial applications

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Friction 2019年第1期7卷 59-73页

作者： Enrico CIULLI Department of Civil and Industrial Engineering University of Pisa

This paper presents experimental rigs of the Research Centre for the Mechanics of Turbomachinery of the Department of Civil and Industrial Engineering of the University of Pisa. Most of them were designed and constructed to allow investigations of real machine components and to furnish more realistic results than basic tribological test rigs. Tilting pad journal bearings, as well as gears and complete gearboxes for advanced industrial applications, can be tested using the rigs described in the paper. A novel test rig with a power rating of approximately 1 MW allows investigations of the static and dynamic characteristics of high-performance tilting pad journal bearings for turbomachinery. A twin disc machine and closed loop gear test rig are used to investigate the different kinds of wear mechanisms occurring in gears. Functional and durability tests on planetary gearboxes for new turbo-fan engines could be performed using another novel large test rig. A circulating power configuration was adopted for most of the rigs so that only the power needed to cover the friction losses has to be supplied, while the circulating power can be more than 20 times higher. All the test rigs include very complex load applications and lubrication plants, as well as dedicated control and data acquisition systems. The rigs and related plants were designed and constructed through strong and fruitful collaborations between the university and some large and small–medium companies. Despite some limitations in the publication of the results as a result of the industrial sensitivity of the data, the synergy among these different actors was stimulating and fundamental for the realization of new advanced industrial applications.

关键词： experimental rigs tilting pad journal bearings twin disc machine gears gearboxes

Microstructural evolution and defect formation in a powder metallurgy nickel-based superalloy processed by selective laser melting

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Journal of Materials Science & Technology 2020年第1期36卷 7-17页

作者： Hongyu Wu Dong Zhang Biaobiao Yang Chao Chen Yunping Li Kechao Zhou Liang Jiang Ruiping Liu State Key Laboratory for Powder Metallurgy Powder Metallurgy Research InstituteCentral South UniversityChangsha 410083China State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization Jinchang 737100China Yuanmeng Precision Technology(Shenzhen)Institute Shenzhen 518063China

In this study,the selective laser melting(SLM)technology has been employed to manufacture a nickelbased superalloy which was conventionally prepared through powder metallurgy(PM)*** microstructural features and defects were systematically investigated both prior to and after heat treatment and compared with the PM *** solidification cracking and liquation cracking were observed in the SLM specimen in which the grain misorientation and low melting point(γ+γ')eutectic played a vital role in their formation *** grains oriented along building direction were ubiquitous,corresponding to strongfiber *** cell structures and melt pools are pervasive and noγ'precipitates were detected at about 10 nm scale before heat *** supersolvus solution and two-step aging treatments,high volume fractionγ'precipitates emerged and their sizes and morphologies were comparable to those in PM alloy.texture is relieved and columnar grains tend to become more equiaxed due to static recrystallization process and grain boundary migration *** annealing twins formed in SLM alloy and are clarified as a consequence of *** results provide fundamental understandings for the SLM PM nickel-based superalloy both before and after heat treatment and demonstrate the potential to fabricate this group of alloys using SLM technology.

关键词： Nickel-based superalloy Selective laser melting Microstructure Defects Annealing twin

Influences of residual stress and micro-deformation on microstructures and mechanical properties for Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy produced by laser powder bed fusion

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Journal of Materials Science & Technology 2021年第16期75卷 174-183页

作者： C.C.Zhang H.L.Wei T.T.Liu L.Y.Jiang T.Yang W.H.Liao National Joint Engineering Research Center of NC Forming Technology and Equipment School of Mechanical EngineeringNanjing University of Science and TechnologyNanjing 210094China

Laser powder bed fusion(LPBF)yields unique advantages during the fabrication of titanium *** the present work,Ti-6.5 Al-3.5 Mo-1.5 Zr-0.3 Si alloy specimens with excellent mechanical performances were fabricated by *** as-built specimens displayed relatively high strength and ductility under modest volume energy densities(VEDs),whereas they manifested high strength with low ductility under high *** investigate the key reason of this phenomenon,the specimens were designed with two VEDs ranges of 60 J/mm^(3) and 85 J/mm^(3).Special attention was paid to the influences of residual stress and micro-deformation on microstructures and mechanical properties for the first *** results indicated that the residual stresses and relative density of the 60 J/mm^(3) range specimens were higher than that of the 85 J/mm3 range *** multiplication and dislocation movement promoted by the residual stress were hindered by the initialα’phase grain boundary(prior-α’GB),leading to the formation ofα’metastable *** mean tensile strength and elongation of the 60 J/mm^(3) range specimens were 1248.1 MPa and 12.3%,respectively,whereas the corresponding values for the 85 J/mm^(3) range specimens were 1405.3 MPa,5.0%,*** deformation,the strength and ductility of the specimens were first improved by lamellar structures generated from prior-α’phases,and then effectively enhanced by the interaction between the{10–12}twins and ***,pores significantly reduced the ductility;hence,high VED specimens with large twins and numerous large pores increased the strength and reduce the ductility.

关键词： Laser powder bed fusion Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy Residual stress twin Mechanical properties

Microstructure of stress-induced martensite in nanocrystalline NiTi shape memory alloy

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Rare Metals 2014年第4期33卷 379-382页

作者： Xiao-Bin Shi Li-Shan Cui Zhen-Yang Liu Da-Qiang Jiang Xiao-Dong Han State Key Laboratory of Heavy Oil Processing China University of Petroleum Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology

The microstructure of stress-induced martensite （SIM） in the nanocrystalline NiTi alloy was investigated by means of transmission electron microscopy （TEM）. The result shows that the multi-variant structure of the martensite is suppressed and only single-variant martensitic twins form after tensile deformation when the grain size is smaller than 80 nm. The normal directions of the （001）B19, twin planes are all. within the range of 45° from the axial direction of the wire. The angle between twin crystals （111）M and （111）x of the SIM is also found to be smaller than that of thermally induced martensite in nanocrystalline NiTi.

关键词： Martensitic transformation Microstructure Shape memory alloys twin

Microstructure and mechanical properties of Zr_(3)Al_(3)C_(5)-based ceramics synthesized by Al-Si melt infiltration

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Journal of Advanced Ceramics 2021年第3期10卷 529-536页

作者： Xiaomeng FAN Yuzhao MA Yangfang DENG Jinxue DING Laifei CHENG Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China College of Materials Science and Engineering Xi’an University of Architecture and TechnologyXi’an 710055China AECC Sichuan Gas Turbine Establishment Chengdu 610500China

In this work,bulk Zr_(3)Al_(3)C_(5)-based ceramics were synthesized by the infiltration of A1-Si melt into zirconium carbide (ZrC) *** phase composition,microstructure,and mechanical properties of as-fabricated ceramics were *** results demonstrate that Si is more effective to reduce the twin boundary energy of ZrC than A1,and thus promotes the decrease of formation temperature of Zr_(3)Al_(3)C_(5).With the infiltration temperatures increasing from 1200 to 1500 ℃,the Zr_(3)Al_(3)C_(5) content increases from 10 to 49 vol%,which is contributed to the increase of flexural strength from 62±9 to 222±10 MPa,and fracture toughness (KIC) from 2.8+0.2 to 4.1±0.3 MPa.m^(1/2).The decrease of mechanical properties for the samples fabricated at 1600 ℃ is ascribed to the abnormal growth of Zr_(3)Al_(3)C_(5) grains.

关键词： Zr_(3)Al_(3)C_(5) ultra-high-temperature ceramics(UHTCs) twin carbide Al-Si alloy

Understanding Solid–Solid(fcc→ω + bcc) Transition at Atomic Scale

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 663-670页

作者： De-Hai Ping National Institute for Materials Science

An atomic transition model of a face-centered cubic （fcc） crystal to a primitive hexagonal co and body-centered cubic （bcc） structures has been crystallographically built. The fcc structure can transform into the co structure through a local shuffling or displacement of atoms about 0.4014 А in iron for aecc iron = 3.59 ,А The bcc structure can form either after the co formation or concurrently by the similar mechanism, or the co structure can be treated as an intermediate stage during the transition of fcc - bcc. Such a transition （fcc- ω ＋ co ＋ bcc transition） can be confirmed by Widmanstitten pattern formed in an iron meteorite, pearlitic structure and martensite composed of bcc-ferrite and ultra-fine co particles in iron--carbon steels. The present fcc-bcc orientation relationship matches with Pitsch＇s one.

关键词： Solid-solid transition ω Transition Martensitic steel Modeling Crystallography twin Phase transformation

Molecular dynamics simulation on the rotation mechanical mechanism of the twinned nanowires

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Molecular dynamics simulation on the rotation mechanical mec...

Microstructure and Properties of M40 Carbon Fibre Reinforced Mg-Re-Zr Alloy Composites

中国计算力学大会2014暨第三届钱令希计算力学奖颁奖大会

作者： Ying Wang Zishun Liu Int.Center for Applied Mechanics State Key Laboratory for Strength and Vibration of Mechanical StructuresXi’an Jiaotong University

There have been a few studies on mechanical mechanism of the periodic twinned nanowires in recent *** purpose of this work is to investigate the behavior of twinned Au nanowires under the torsion *** this study,the Molecular Dynamics(MD)software LAMMPS is adopted to carry out simulation of the twinned nanowires *** parameter of Common Neighbor Analysis is used to mark the different atoms which have different local crystal structures around *** results show that the Common Neighbor Analysis of some atoms on three main regions have been changed a lot in the rotation process of twinned *** local crystal structures of some atoms on the two regions near the ends of nanowires have been altered,but have gradually recovered during the rotation *** found that some fcc planes of the middle area have become the hcp planes with the deformation increasing,and the hcp lattice represents twin *** middle plane of the nanowire is also a plane of the middle area,which has changed from twin plane into grain boundary,then fcc plane.

关键词： molecular dynamics twin rotation mechanical mechanism nanowire

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Journal of Materials Science & Technology 2009年第3期25卷 423-426页

作者： Gaohui Wu Meihui Song Ziyang Xiu Ning Wang Wenshu Yang School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

M40 carbon fibre reinforced rare earth magnesium alloy ZM6 composites with fibre volume fraction about 60% were fabricated by pressure infiltration method. The microstructure, interracial morphology, and precipitation were studied by scanning electron microscopy, transmission electron microscopy, and energy dispersive X- ray spectrometer. It was shown that the interfaces between Mg alloy and fibres were well bonded and free from cracks. The Mg12Nd phase was preferentially precipitated at the fibre/matrix interfaces, leading to the segregation of Nd at the interfaces and the dramatic decrease of Mg12Nd precipitation in the matrix far from interfaces. Crystal defects such as high-density dislocations and twins were observed in the matrix near the fibre/matrix interface. A high bending strength （1393 MPa） and elastic modulus （190 GPa） were achieved in M40/ZM6 composite.

关键词： Magnesium matrix composites Microstructure Dislocations twin

Recrystallization Texture and Microstructure of Metal Substrate for Y123 Coated Superconductor

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Journal of Rare Earths 2003年第4期21卷 450-452页

作者：刘慧舟史锴杨坚袁冠森 Superconductivity Research Center

The cube textured pure Ni and non magnetic Cu Ni tapes were obtained by rolling and recrystallization, and these tapes are suitable as substrates of the second generation high temperature superconducting tape. The texture of tapes was studied using Orientation Distribution Function (ODF) and φ scans. The results indicate that sharp cube texture of Cu 0 70 Ni 0.30 and pure Ni was formed at 1000 ℃ and that of Cu 0 85 Ni 0.15 was formed at 900 ℃. The intensities of cube texture differ from each other. Uniform equiaxial crystallites are formed in all the tapes and the size of Cu 0.85 Ni 0.15 is larger than that of Cu 0.70 Ni 0.30 and pure Ni. Annealing twin is formed in Cu 0.85 Ni 0.15 and Cu 0.70 Ni 0.30 .

关键词： metal materials high temperature superconductor cube texture substrate twin rare earths