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Research progress on formation and suppression of crack defects in oxide eutectic ceramics by laser additive manufacturing

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CAILIAO GONGCHENG-JOURNAL OF MATERIALS ENGINEERING 2024年第5期52卷 34-45页

作者： Yao, Jiatong Su, Haijun Jiang, Hao Chen, Qian Shen, Zhonglin Yu, Minghui Zhang, Zhuo Guo, Min Northwestern Polytech Univ State Key Lab Solidificat Proc Xian 710072 Peoples R China Northwestern Polytech Univ Shenzhen Res Inst Shenzhen 518057 Guangdong Peoples R China

Oxide eutectic ceramics have excellent high specific strength , high temperature resistance , corrosion resistance , oxidation and creep resistance , and so on , which are considered to be the promising materials to be used in ultra -high temperature oxidation , corrosion and other extreme environments. It shows great application prospects in the new generation of high thrust -to -weight ratio aero-engine for hightemperature hot -end structural components. Laser additive manufacturing technology has become one of the most promising cutting -edge technologies for the preparation of high-performance complex structural components in recent years. Crack defect is easy to occur in the process of laser rapid solidification of ceramics , which seriously affects the quality and performance of the oxide eutectic ceramics components. So , it has become a key factor restricting the engineering application. Two typical laser additive manufacturing technologies for ceramics including laser engineered net shaping and laser power bed fusion were briefly summarized. The crack morphology characteristics of different shaped components formed by the above two technologies were analyzed and compared. The formation mechanism of cracks in laser additive manufacturing of oxide ceramics was explored from the perspectives of microstructure characteristics ,stress state. Further ,a systematic summary was presented focusing on the improvement of microstructures and the reduction of thermal stress to inhibit crack formation through optimization of process parameters ,compositional design ,and outfield assistance. Finally ,it is pointed out that the future development trends and breakthrough directions of oxide eutectic ceramics by laser additive manufacturing in terms of and factors ,and research.

关键词： oxide eutectic ceramic laser additive manufacturing crack defect formation mechanism crack suppression DIRECTED ENERGY DEPOSITION mechanical-properties PROCESS OPTIMIZATION ALUMINA CERAMICS MICROSTRUCTURE COMPOSITE ZIRCONIA COMPONENTS STRENGTH

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Influence of glass-based dental ceramic type and thickness with identical shade on the light transmittance and the degree of conversion of resin cement

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International Journal of Oral Science 2018年第1期10卷 44-49页

作者： Soram Oh Su-Mi Shin Hyun-Jung Kim Janghyun Paek Sung-Joon Kim Tai Hyun Yoon Sun-Young Kim Department of Conservative Dentistry Graduate School Kyung Hee University Seoul Korea Department of Prosthodontics School of Dentistry Kyung Hee University Seoul Korea Department of Dentistry School of Medicine Jeju National University Jeju Korea Department of Physics Korea University Seoul Korea and SDepartment of Conservative Dentistry Dental Research Institute School of Dentistry Seoul National University Seoul Korea

The purpose of this study was to assess the influence of the types and thicknesses of glass ceramic plates on light transmittance and compare the degrees of conversion(DC) of resin cement under the ceramic materials. Three ceramic plates with thicknesses of 0.5, 1.0, 2.0, and 4.0 mm were fabricated from each of five commercial ceramic blocks in shade A2: high-translucency and low-translucency IPS Empress CAD(EmpHT and EmpLT); high-translucency and low-translucency IPS e.max CAD(EmxHT and EmxLT); and Vita Mark Ⅱ(Vita). The translucency parameter was obtained using a colorimeter. The light transmittance rate was measured using a photodetector attached to an optical power meter. The DC of a resin cement(Variolink N) underneath the ceramic plates was examined by Fourier transform infrared spectroscopy. The translucency parameter, light transmittance rate, and DC showed significant differences by ceramic type and thickness(P 0.05). Both type and thickness of the glass ceramics significantly influenced the light transmittance and DC of the light-cured resin cement beneath the ceramic of the same shade.

关键词： MICROTENSILE BOND STRENGTH mechanical-properties LUTING AGENT CURING MODE POLYMERIZATION TRANSMISSION TRANSLUCENCY COMPOSITE PORCELAIN HARDNESS

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Anomalous crystal structure of γ" phase in the Mg-RE-Zn(Ag) series alloys:Causality clarified by ab initio study

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Journal of Materials Science & Technology 2020年第1期36卷 167-175页

作者： Junyuan Bai Xueyong Pang Xiangying Meng Hongbo Xie Hucheng Pan Yuping Ren Min Jiang Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Research Center for Metallic Wires Northeastern UniversityShenyang 110819China

The crystal structure of the single-unit-cell thickness γ " phase,as a key strengthening phase in Mg-REZn(Ag) series alloys,has been extensively studied,and several structural models have been proposed in the past two decades.However,these reported models,and even the lattice constants at the same proposed structure,are scattered severely,which has led to considerable confusion and not available for further mechanical property simulation and prediction of Mg alloys containing this phase.In this study,by using first-principles calculations,the crystal structure of y" phase is clarified,resolving the discrepancies among different experiments,and its intrinsic mechanical properties have also been studied for the first time.It is verified that the γ " phase contains quasi-five atomic layers,instead of the previously reported tri-layer,and surprisingly,its crystal structure has many variants,which would change with the alloy composition.Besides,with the help of the simulated selected area electron diffraction(SAED) patterns,it is found that the atoms in the central layer remain partially ordered distribution,and this ordered extent primarily depends on the atomic ratio of RE:Zn(Ag) and the solute content in an alloy.That is,the ordered extent increases with decreasing the atomic ratio of RE:Zn(Ag) and/or increasing solute content of alloy,and vice versa.Ag and Zn dissolved in the γ" phase would produce almost opposed mechanical anisotropy for the γ " phase under the identical crystal structure,and the addition of Ag shows more efficient on increasing the shear modulus of γ" phase.

关键词： First-principles γ"phase Mg-RE-based series alloys Crystal structure mechanical-properties

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Optimization of Energy Scope for Titanium Nitride Films Grown by Ion Beam-Assisted Deposition

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Chinese Physics Letters 2006年第1期23卷 178-181页

作者：李伟马忠权王烨王德明 Department of Physics Shanghai University Shanghai 200444

The deposited energy during film growth with ion bombardment, correlated to the atomic displacement on the surface monolayer and the underlying bulk, has been calculated by a simplified ion-solid interaction model under binary collision approximation. The separated damage energies caused by Ar ion, different for the surface and the bulk, have been determined under the standard collision cross section and a well-defined surface and bulk atom displacement threshold energy of titanium nitride （TIN）. The optimum energy scope shows that the incident energy of At＋ around 110eV for TiN （111） and 80eV for TiN （200） effectively enhances the mobility of adatom on surface but excludes the damage in underlying bulk. The theoretical prediction and the experimental result are in good agreement in low energy ion beam-assisted deposition.

关键词： THIN-FILMS mechanical-properties SCATTERING MICROSTRUCTURE SURFACES PLASMA

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Effects of Raw Material Content on Efficiency of TiN Synthesized by Reactive Ball Milling Ti and Urea

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Chinese Physics Letters 2009年第7期26卷 355-358页

作者：孙金峰李晓普梁宝岩赵玉成王明智 State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004

Ti and urea mixed according to the molar ratios of 2：1, 3：1 and 4：1 axe milled under the same condition. The structures of the as-synthesized powders are analyzed by an x-ray diffractometer （XRD）. The decomposed temperature of the urea and the products decomposed are characterized by differential scanning calorimetry （DSC） and thermogravimetry analysis-Fourier transform infrared （TG-FTIR） spectrometry. The results show that the reaction progress is a diffusion reaction. The efficiency of TiN synthesized by reactive ball milling can be increased by increasing the content of Ti. The reactive ball milling time decreases from more than 90 h to 40 h correspond- ing to the content ratio between Ti and urea increasing from 2：1 to 4：1. Ammonia gas （NH3） and cyanic acid （HNCO）, the decomposed products of urea, react with the refined Ti to form TiN. The grain refinement of Ti has a significant effect on the efficiency of reactive ball milling.

关键词： mechanical-properties MICROSTRUCTURE TITANIUM CERMETS COMPOSITE NITRIDES

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Effects of Processing Parameters on Microstructure and properties of Nanoscale ZrC/ZrB2 Multilayered Coatings

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Chinese Physics Letters 2006年第10期23卷 2838-2840页

作者：杨瑾张学华曹猛王明霞梁金岭李德军 College of Physics and Electronic Information Science Tianjin Normal University Tianjin 300074

ZrC/ZrB2 multilayered coatings with bilayer periods of 3.5-40nm are synthesized by rf magnetron sputtering. Analyses of x-ray diffraction, scanning electron microscopy and nanoindentation indicate that multilayered coatings possess much higher hardness and greater fracture resistance than monolithic ZrC and ZrB2 coatings. A maximum hardness （41.TCPa） and a critical fracture load （73.7mN） are observed in the multilayer with A = 32 nm deposited at the substrate bias -40 V. Higher residual stress built in the ZrC layer can be released by periodic insertion of ZrB2 into the ZrC layer. A clear multilayered structure with mixed ZrB2（001）, ZrB2 （002） and ZrC （111） orientations should be responsible for the enhanced mechanical properties.

关键词： mechanical-properties THERMAL-STABILITY FILMS

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Elastic Modulus and Hardness of Cr-Nb Nano-Multilayers

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Chinese Physics Letters 2007年第9期24卷 2635-2638页

作者：杨孟锦赖文生潘峰 Laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua University Beijing 100084

Cr-Nb nano-multilayered films with various modulation wavelengths A are prepared by e-gun evaporation and their mechanical properties are investigated. Cr and Nb both have bcc structures with large differences in lattice constants and Young＇s modulus, which are supposed to favour modulus enhancement. Nevertheless, nano-indention measurements show no enhancement for the modulus and a slight decrease for the hardness with decreasing A down to 5 nm. This is mainly due to counter-contribution to modulus from adjacent layers subjected to reverse strains, in agreement with recent theoretical study, while the decrease of hardness arises from grain boundary sliding. Interestingly, at A = 3 nm, the hardness of the film has an increase of 44% relative to the value of a rule of mixture, owing to the emergence of a new phase for reconciling the structure difference at the interfaces.

关键词： NI THIN-FILMS mechanical-properties SUPERLATTICES NICKEL FOILS CU NANOINDENTATION INDENTATION PALLADIUM STRESS

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Effects of Alloy Elements (C, B, Fe, Si) on the Ti-Al Binary Phase Diagram

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Journal of Materials Science & Technology 1999年第1期15卷 58-62页

作者： Li, JT Zong, YP Hao, SM Northeastern Univ Dept Mat Sci & Engn Shenyang 110006 Peoples R China

The alpha(alpha(2))/gamma phase equilibria in Ti-Al-X(X=C,B,Fe,Si in at, pct) ternary systems were studied by equilibrium heat-treatment and EPMA. The results show that the addition of B to the Ti-Al binary system leads to a shift of both alpha(alpha(2))/[alpha(alpha(2))+gamma] and [(alpha(alpha(2))+gamma]/gamma phase boundaries to Al-rich side and 0.1 B addition decreases T-alpha by 18 degrees C. The addition of C leads to a shift of [alpha(alpha(2))+gamma]/gamma phase boundary to Al-rich side but the effect of 0.2 at, pet C addition on T-alpha is very slight. The addition of Fe results in alpha(alpha(2))/[alpha(alpha(2))+gamma] and [alpha(alpha(2))+gamma]/gamma phase boundaries shifting to Ti-rich side and 1.0 Fe addition increases T-alpha by 90 similar to 110 degrees C. The addition of Si leads to a shift of alpha(alpha(2))/[alpha(alpha(2))/[alpha(alpha(2))+gamma] phase boundary to Ti-rich side and the 0.3 Si addition increases T-alpha by 80 similar to 110 degrees C. The solubilities for C, B and Si in alpha(alpha(2)) phase are higher than those in the gamma phase but the solubility for Fe in alpha(alpha(2)) phase is lower than that in gamma phase.

关键词： mechanical-properties TITANIUM ALUMINIDE

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On Structure and Thermodynamics of Coherent Nanocrystals

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Journal of Materials Science & Technology 1995年第3期11卷 157-164页

作者： LUCK, R LU, K ACAD SINICA INST MET RESNATL KEY LAB RAPIDLY SOLIDIFIED NONEQUILIBRIUM ALSHENYANG 110015PEOPLES R CHINA ACAD SINICA INST MET RESINT CTR MAT PHYSSHENYANG 110015PEOPLES R CHINA MAX PLANCK INST MET RES INST WERKSTOFFWISSENSCHD-70174 STUTTGARTGERMANY

Several classifications for the nanocrystalline morphologies are introduced. It is: demonstrated that coherency and coherence strain are important physical quantities, which influence the stability, the morphology and... 详细信息

关键词： mechanical-properties ELECTRON-MICROSCOPY AMORPHOUS NIZR2 STATE TRANSITION CRYSTALLIZATION PARTICLES ALLOYS

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