检索结果-南通市图书馆

thermal cycling behavior of nanostructured and conventional yttria-stabilized zirconia thermal barrier coatings via air plasma spray

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2023年第11期42卷 3859-3869页

作者： Cheng-Yang Jiang Min Feng Chun-Tang Yu Ze-Bin Bao Sheng-Long Zhu Fu-Hui Wang Shenyang National Laboratory for Materials Science Northeastern UniversityShenyang110819China Institute of Metal Research Chinese Academy of SciencesShenyang110016China

Two thermal barrier coating(TBC)systems comprising NiCoCrAlY bond coat onto a second-generation Ni-based single crystal superalloy and nano structured4 mol%Y_(2)O_(3)-stabilized ZrO_(2)(4YSZ)and conventional yttria-stabilized zirconia(YSZ)top coats upwardly were deposited by approaches of arc ion plating(AIP)and air plasma spray(APS).As indicted by the experimental results,the 4YSZ TBCs exhibited superior thermal cycling resistance compared with conventional YSZ TBCs at 1100℃.The 4YSZ top coat exhibited higher toughness due to its intrinsic property of nanocrystalline structure,homogeneously distributed and diverse directions of pores and preexisted *** cracks and spallation in 4YSZ TBCs occurred at the interface of top coat and thermally grown oxide(TGO)***,the crack initiation and propagation started along the lamellar interface in the top coat of conventional YSZ TBCs,leading to the rapid crack bridging and subsequent spalling of top ***,before and after oxidation,the 4YSZ top coat showed higher hardness compared to conventional YSZ top *** mechanism and distribution of residual stress in TGO for the 4YSZ TBCs were investigated in the current study.

关键词： TBC Nanocrystalline TGO thermal cycling Toughness

thermal cycling performance of La_(2)Ce_(2)O_(7)/YSZ TBCs with Pt/Dy co-doped NiAl bond coat on single crystal superalloy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第9期40卷 2568-2578页

作者： Zi-Min Zhou Hui Peng Lei Zheng Hong-Bo Guo Sheng-Kai Gong School of Materials Science and Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology Beihang UniversityBeijing 100191China Key Laboratory of Aerospace Materials and Performance(Ministry of Education) Beihang UniversityBeijing 100191China

thermal barrier coatings(TBCs) consisting ofLa_(2)Ce_(2)O_(7)(LCO) and Y_(2)O_(3)-stabilized-ZrO_(2)(YSZ) doubleceramic layer and Dy/Pt co-doped NiAl bond coat were produced by electron beam physical vapor deposition(EBPVD). thermal cyclic performance of the TBCs was evaluated by flame shock testing at 1300 ℃. For comparison, the TBCs with a undoped NiAl bond coat were also studied. The microstructural evolution and failure mechanisms of the above TBCs during thermal cycling were investigated. Spallation failure of the TBCs with the undoped bond coat occurs after around 500 cycles by cracking at the interface between YSZ ceramic layer and thermally grown oxides(TGO) layer. The TBCs with Pt/Dy modified bond coat reveal improved interface bonding even after 1200 thermal cycles, whereas some delamination cracks are presented in the LCO layer. On the other hand,the Pt/Dy modified bond coat effectively suppresses the formation of the needle-like topologically closed packed phases(TCP) in the single crystal superalloy.

关键词： thermal barrier coatings NiAl bond coat Pt/Dy co-doping Electron beam physical vapor deposition thermal cycling Interdiffusion

Microstructural Evolution and Cracking of Pb-free Ball Grid Array Assemblies under thermal cycling

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2007年第1期23卷 85-91页

作者： Wei WANG Zhongguang WANG Aiping XIAN Jianku SHANG Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

Two kinds of CBGA （ceramic ball grid array） assemblies were made by reflow soldering process using two different Pb-free solders. Microstructural evolution and cracks induced by thermal cycling in CBGA assemblies were examined by scanning electron microscopy （SEM） and finite element method （FEM）. Before thermal cycling, intermetallic compounds （IMCs） Cu6Sn5 and Ag3Sn were observed at the solder interface between Cu and Ag metallizations, respectively. After thermal cycling, another IMC Cu3Sn was observed near the Cu pad in both two assemblies and the layers of Cu6Sn5 and Ag3Sn became thicker. As a result of thermal cycling, cyclic stress and strain were accumulated in the solder joint leading to fatigue cracking. Both experiments and FEM revealed that cracks preferred to initiate at the corner of each solder joint. Multi-modes of the crack propagation were found in the two assemblies. Based on Coffin-Manson equation, the thermal fatigue life was calculated and the predicted life showed good agreement with the experimental results.

关键词： CBGA thermal cycling FEM Assembly Cracking

Microstructure,wetting property of Sn-Ag-Cu-Bi-xCe solder and IMC growth at solder/Cu interface during thermal cycling

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第3期40卷 714-719页

作者： Yuan Wang Xiu-Chen Zhao Ying Liu Yong Wang Dong-Mei Li School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Center of Packaging and Testing Beijing Microelectronics Technology InstituteBeijing 100076China

The effects of adding small amounts of cerium(Ce) to Sn-3.3 Ag-0.2 Cu-4.7 Bi solder on microstructure,wettability characteristic,interfacial morphology and the growth of interfacial intermetallic compound(IMC) during thermal cycling were investigated by optical microscopy(OM),scanning electron microscopy(SEM) and solderability *** is found that the p-Sn phase,Ag_(3)Sn phase and Cu6 Sn5 phase in the solder are refined and the wetting force *** is an active element;it more easily accumulates at the solder/flux interface in the molten state,which decreases the interfacial surface energy and reduces the driving force for IMC formation on Cu substrate;therefore,the thickness of IMC at the solder/Cu interface decreases when appropriate Ce was added into the ***,the Ce-containing solders have lower growth rate of interfacial IMC than solders without Ce during the thermal cycling between-55 and 125℃.When the Ce content is 0.03 wt% in the Sn-3.3 Ag-0.2 Cu-4.7 Bi solder,the solder has the best wettability and the minimum growth rate of interfacial IMC layer.

关键词： Lead-free solder Rare earth element Microstructure Wettability Intermetallic compound thermal cycling

Revealing the oxidation growth mechanism and crack evolution law of novel Si-HfO_(2)/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5)environmental barrier coatings during thermal cycling

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第10期13卷 1677-1696页

作者： Ruixiang Liu Wenping Liang Qiang Miao Hui Zhao Xiaofeng Zhang Meng Zhang Rongxue Yan Brindha Ramasubramanian Seeram Ramakrishna College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Mechanical Engineering National University of SingaporeSingapore 117575Singapore National Engineering Laboratory for Modern Materials Surface Engineering Technology Institute of New MaterialsGuangdong Academy of SciencesGuangzhou 510651China

The development of Si-HfO_(2)/Yb_(2)Si_(2)O_(7)/Yb_(2)SiO_(5)environmental barrier coatings(EBCs)aims to improve the operational temperature and longevity of ceramic matrix composites(CMCs)in turbine ***,several critical questions remain unanswered,including the oxidation mechanism of Si-HfO_(2)bond coating,the compatibility of its mixed thermally grown oxide(m-TGO)with adjacent layers during thermal cycling,and the evolution pattern of vertical mud-cracks that impact the overall performance in *** plasma spraying physical vapor deposition(PS-PVD),we fabricated these EBCs on a CMC substrate,and thermal cycling tests at 1400,1450,and 1500℃ revealed that their durability reached 200 h.m-TGO growth followed a parabolic model,with the oxygen diffusion activation energy being 133.69 kJ/mol between 1400 and 1450℃ and 101.47 kJ/mol from 1450 to 1500℃,emphasizing that the transport of molecular oxygen is key to controlling the oxidation of m-TGO in this EBC *** residual stresses and stored elastic strain energy build up between m-TGO and adjacent layers,especially around the cristobalite phase transition temperature,causing interlaminar crack formation in later thermal cycles,the stored elastic strain energy remains lower than that of the silicon oxide-thermally grown oxide(SiO_(2)-TGO)formed in Si bond coating *** addition to[110]dislocations,(001)twinning and interaction zones between twinning and dislocations were discovered for the first time,driving the bifurcation of mud ***,controlling the mud-crack density is vital for protection of Yb_(2)SiO_(5)layer,as bifurcated mud-crack tips may converge with adjacent mud-cracks.

关键词： environmental barrier coatings(EBCs) thermal cycling oxidation crack propagation defects

Composition optimization, high-temperature stability, and thermal cycling performance of Sc-doped Gd_(2)Zr_(2)O_(7) thermal barrier coatings: Theoretical and experimental studies

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2022年第3期11卷 454-469页

作者： Lei GUO Bowen LI Yuxian CHENG Lu WANG School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced Joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China AECC Shenyang Liming Aero-Engine Co. Ltd.Shenyang 110043China

Sc was doped into Gd_(2)Zr_(2)O_(7) for expanding the potential for thermal barrier coating (TBC) applications. The solid solution mechanism of Sc in the Gd_(2)Zr_(2)O_(7) lattice, and the mechanical and thermophysical properties of the doped Gd_(2)Zr_(2)O_(7) were systematically studied by the first-principles method, based on which the Sc doping content was optimized. Additionally, Sc-doped Gd_(2)Zr_(2)O_(7) TBCs with the optimized composition were prepared by air plasma spraying using YSZ as a bottom ceramic coating (Gd-Sc/YSZ TBCs), and their sintering behavior and thermal cycling performance were examined. Results revealed that at low Sc doping levels, Sc has a large tendency to occupy the lattice interstitial sites, and when the doping content is above 11.11 at%, Sc substituting for Gd in the lattice becomes dominant. Among the doped Gd_(2)Zr_(2)O_(7), the composition with 16.67 at% Sc content has the lowest Pugh’s indicator (G/B) and the highest Poisson ratio (σ) indicative of the highest toughness, and the decreasing trends of Debye temperature and thermal conductivity slow down at this composition. By considering the mechanical and thermophysical properties comprehensively, the Sc doping content was optimized to be 16.67 at%. The fabricated Gd-Sc coatings remain phase and structural stability after sintering at 1400 ℃ for 100 h. Gd-Sc/YSZ TBCs exhibit excellent thermal shock resistance, which is related to the good thermal match between Gd-Sc and YSZ coatings, and the buffering effect of the YSZ coating during thermal cycling. These results revealed that Sc-doped Gd_(2)Zr_(2)O_(7) has a high potential for TBC applications, especially for the composition with 16.67 at% Sc content.

关键词： thermal barrier coating(TBC) first-principles calculation solid solution mechanism high-temperature stability thermal cycling

Mechanical property and structural changes by thermal cycling in phase-separated metallic glasses

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第19期78卷 144-154页

作者： Y.Tang H.B.Xiao X.D.Wang Q.P.Cao D.X.Zhang J.Z.Jiang International Center for New-Structured Materials(ICNSM) Laboratory of New-Structured MaterialsState Key Laboratory of Silicon Materialsand School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China State Key Laboratory of Modem Optical Instrumentation Zhejiang UniversityHangzhou.310027China

Nondestructive cryogenically thermal cycling has been a simple but effective treatment to enhance mechanical properties of glassy ***,how the structural heterogeneities on nanometer scales are affected by thermal cycling is still an ***,we report the response of spatial heterogeneities in three selected Ti_(41)Zr_(25)Be_(28)Fe_(6),Zr_(56)Co_(14)Cu_(14)Al_(16)and Zr_(42)Y_(14)Co_(22)Al_(22)(at.%)metallic glasses(MGs)with different compositions to the thermal cycling,which show significantly different structure and properties after the same treatments and could be ascribed to the joint contribution of relaxation and rejuvenation induced by thermal *** rejuvenation is initially prevailed in a Zr-Y-containing MG,whereas the relaxation is dominant in a Cu-Co-containing MG,both eventually entering into a dynamic equilibrium *** employing nanometer-scale structural models,the intrinsic correlation between the spatial heterogeneity and thermal cycling is *** discovery could provide the fundamental understanding of the role of spatial heterogeneity in influencing the macroscopic properties of MGs via thermal cycling and help design high-performance glassy materials by tailoring their atomic structures with suitable thermal treatments.

关键词： thermal cycling Metallic glass Spatial heterogeneity Relaxation Rejuvenation

Effect of thermal cycling on Properties and Microstructure of SnAgCuCe Soldered Joints in QFP Devices

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2011年第4期24卷 561-566页

作者： ZHANG Liang XUE Songbai GAO Lili ZENG Guang YU Shenglin SHENG Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China School of Mechanical ＆ Electrical Engineering Xuzhou Normal University Xuzhou 221116 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

Increasing global concern about the environment is bringing regulatory （European directives） and consumer （＂green products＂） pressure on the electronics industry in Europe and Japan to reduce or completely eliminate the use of lead （Pb） in products. Among all lead-free solder alloys, SnAgCu solder system, which has better thermo-mechanical properties compared with those of SnPb solder, is proven to be one of the promising candidates for electronic assembly. Previous work also revealed that adding a small amount of rare earth Ce into SnAgCu solder can visibly improve the properties and inhibit the excessive growth of the intermetallic compound layer. thermal fatigue properties of SnAgCuCe soldered joints in QFP devices under thermal conditions have been investigated by finite element method and experiments. Based on creep model of low stress and high stress, corresponding creep subroutine was established for simulating the stress and strain response of SnAgCuCe soldered joint from -55 ℃ to 125 ℃, and fatigue life was calculated using creep fatigue life prediction equation. Moreover, thermal cycling experiments were conducted, the experimental results were found to be close to the simulated results. In addition, the tensile force of SnAgCuCe soldered joints decreased with increasing number of thermal cycles, and the fracture mechanism transformed from toughness fracture to brittle intergranular fracture. Moreover the tensile force changes and fracture microstructure evolution could benefit the quantitative evaluations of the mechanical performances of lead-free soldered joints under thermal cycling loadings.

关键词： finite element method creep equation thermal cycling fatigue life

Life Prediction of Ball Grid Array Soldered Joints under thermal cycling Loading by Fracture Mechanics 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1期17卷 165-166页

作者： Hongyuan FANG Li WANG Yiyu QIAN National Key Laboratory of Advanced Welding Production Technology Harbin Institute of TechnologyHarbin 150001China

Fatigue crack propagation life of ball grid array (BGA) soldered joints during thermal cycling loading was investigated by fracture mechanics approach using finite element analysis. The relationships between the strain energy release rate (G) and crack size (a), thermal cycle numbers (N) can be derived.' Based on the relationships, fatigue life of the soldered joints was determined. The results showed that crack propagation life was higher than crack initiation life. Therefore, it appears that it is more appropriate to predict the fatigue life of soldered joints using the fracture mechanics method.

关键词： Fracture Mechanics thermal cycling Soldered Joints soldered joints fracture mechanics crack propagation strain energy release rate fatigue life finite element analysis crack initiation thermal cycling ball grid array