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Journal of Materials Science & Technology 2021年第8期67卷 127-134页

作者： mei-jun liu Guan-jun Yang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an fiaotong UniversityXi’anShaanxi710049PR China

Plasma spray-physical vapor deposition(PS-PVD)has exhibited the potential ability to prepare columnar structures for advanced thermal barrier coatings(TBCs).The coating structure is nominally affected by operating parameters,but it is controlled by the type of deposition unit actually and *** order to realize the columnar structure deposited by gaseous phase units,the transition behavior of gaseous phase units to clusters must be fundamentally *** work investigated the transport process of gaseous phase units in the PS-PVD near-substrate boundary layer along with the condensation *** Monte Carlo method was used to examine the transport process and condensation behavior of gaseous phase units under different scale boundary *** results show that it is easier to form more numerous larger clusters at the edge of the plasma jet than at the *** on the understanding of the changes in deposition unit caused by the condensation of gaseous phase in the near-substrate boundary layer of PS-PVD,an outlook towards TBCs with different structures is *** it is in good agreement with the experimental data.

关键词： Condensation behavior Transport process Cluster Boundary layer PS-PVD

Solid dust induced roughening and overheating of TBC-coated superalloy

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Journal of Materials Science & Technology 2024年第13期180卷 69-79页

作者： Jia-Qi Han mei-jun liu Javad Mostaghimi Guan-jun Yang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049China Department of Mechanical and Industrial Engineering University of TorontoTorontoON M5S 3G8Canada

Thermal barrier coatings(TBC)on superalloy blade/vane enable an increase in turbine inlet temperature(TIT)and aero-engine ***,the deposition of dust on TBC significantly ablates superalloys and becomes a bottleneck for advanced engine *** paper presents a comprehensive mod-eling approach,based on an experiment involving dust deposition on a TBC-coated substrate,aimed at understanding the fundamental cause of substrate *** results show that a significant increase in surface roughness is obtained experimentally with dust *** temperature field within the TBC-substrate system is disturbed by surface ***,the film cooling is seriously *** the dust accumulated on the TBC surface also contributes to heat insulation by increas-ing the effective TBC thickness,localized overheating of the substrate occurs and then leads to ablation and premature failure of the *** elucidation of the overheating mechanism could inform the development of strategies to resist dust accumulation in advanced aero engines.

关键词： Thermal barrier coating Superalloy Dust Roughness Overheating

Cytoskeleton in Pollen and Pollen Tubes of Ginkgo biloba L.

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Journal of Integrative Plant Biology 2005年第8期47卷 952-958页

作者： jun-mei liu Hong ZHANG Yan LI State Key Laboratory of Plant Physiology and Biochemistry College of Biological Sciences China Agricultural University Beijing 100094 China Department of Horticulture Hebei Agricultural University Baoding 077001 China

The distribution of F-actin and microtubules was investigated in pollen and pollen tubes of Ginkgo biloba L. using a confocal laser scanning microscope after fluorescence and immunofluorescence labeling. A dense F-actin network was found in hydrated Ginkgo pollen. When Ginkgo pollen was germinating, F-actin mesh was found under the plasma membrane from which the pollen tube would emerge. After pollen germination, F-actin bundles were distributed axially in long pollen tubes of G. biloba. Thick F-actin bundles and network were found in the tip of the Ginkgo pollen tube, which is opposite to the results reported for the pollen tubes of some angiosperms and conifers. In addition, a few circular F-actin bundles were found in Ginkgo pollen tubes. Using immunofluorescence labeling, a dense microtubule network was found in hydrated Ginkgo pollen under confocal microscope. In the Ginkgo pollen tube, the microtubules were distributed along the longitudinal axis and extended to the tip. These results suggest that the cytoskeleton may have an essential role in the germination of Ginkgo pollen and tube growth.

关键词： F-actin Ginkgo biloba microtubules pollen tube.

Interference Pattern of Density-Density Correlation for Incoherent Atoms with Vortices Released from an Optical Lattice

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Chinese Physics Letters 2011年第1期28卷 26-29页

作者： XU Zhi-jun ZHANG Dong-mei liu Xia-Yin College of Science Zhejiang University of Technology Hangzhou 310023

For a series of incoherent condensate atomic clouds with vortices （an orbital angular momentum） released from an optical lattice, the density-density correlation function of this freely expanding ultracold gases is theoretically investigated. It is shown that the nonzero angular momentum of the atoms has an important effect on the fringe pattern of density-density correlation. Particularly, for a short expansion time, even the rotation direction of the atoms could have an observable effect on the fringe pattern. Observation of this specific fringe pattern would constitute experimental evidence for the presence of a vortex in an atomic condensate.

关键词： Quantum gases, liquids and solids Optics, quantum optics and lasers Statistical physics and nonlinear systems

Heterogeneous layered structure in thermal barrier coatings by plasma spray-physical vapor deposition

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Journal of Advanced Ceramics 2023年第2期12卷 386-398页

作者： Yan-Hong LU Lu HUANG mei-jun liu Guan-jun YANG Chang-Jiu LI State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China

The unique columnar structure endows thermal barrier coatings(TBCs)prepared by plasma spray-physical vapor deposition(PS-PVD)with high thermal insulation and long ***,the coating delamination failure resulting from an intra-column fracture(within a column rather than between columns)is a bottleneck in the solid dust particle impact environment for *** clarify the intra-column fracture mechanism,a basic layer deposition model is developed to explore a heterogeneous weak-to-strong layered structure formed by a local transient in-situ deposit *** the PS-PVD,an in-situ deposit surface is continuously updated due to constantly being covered by vapor condensation,showing a transient temperature,which means that the in-situ deposit surface temperature rises sharply in short period of 0.2 s of depositing a thin layer during a single ***,the increasing temperature of the in-situ deposit surface results in an experimentally observed heterogeneous weak-to-strong structure,showing a continuous transition from a porous weak structure at the bottom region to a dense strong structure at the top *** structure easily makes the intra-column fracture at the porous weak *** results shed light on improving TBC lifetime by restraining the intra-column fracture.

关键词： transient temperature in-situ deposit surface heterogeneous layered structure fracture mechanism plasma spray-physical vapor deposition(PS-PVD)

Lightweight epoxy-based abradable seal coating with high bonding strength

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Journal of Materials Science & Technology 2021年第10期69卷 129-137页

作者： Yun-Qi Tong Qiu-Sheng Shi mei-jun liu Guang-Rong Li Chang-Jiu Li Guan-jun Yang State Key Laboratory for Mechanical Behavior o f Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an710049China

To gain high efficiency and low fuel consumption, aluminum-based abradable seal coatings had been widely used in the compressor casing of aero engines or gas turbines owing to the low elastic modulus. However, the adhesive transfer phenomenon frequently occurs when the radial rubbing generates between titanium alloy blade tips and aluminum-based coating. It tends to increase scratch force and results in blades vibration and even engine jam. To eliminate this problem, a new lightweight epoxy-based abradable seal coating with high bonding strength was developed by an effective and porosity controllable mixing process that distributes spherical pores uniformly in the continuous matrix. A lightweight coating of 63% porosity with a hardness of 33.1(HR15 Y) can be reached when the content of hollow microspheres is 31 wt.%. The coating density is 0.5 g/cm3 and the bonding strength is as high as 18 *** performance of the epoxy-based coating is comprehensively better than aluminum-based coatings in five essential indices. This study is expected to provide a new technical path for obtaining high-quality abradable seal coatings to guarantee the efficient and safe operation of compressors.

关键词： Epoxy-based seal coating Porosity HR15Y Lightweight High bonding strength

Pressure infiltration of molten aluminum for densification of environmental barrier coatings

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Journal of Advanced Ceramics 2022年第1期11卷 145-157页

作者： Lin DONG mei-jun liu Xiao-Feng ZHANG Xue-Shi ZHUO Jia-Feng FAN Guan-jun YANG Ke-Song ZHOU State Key Laboratory for Mechanical Behavior ofMaterials School ofMaterials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China National Engineering Laboratory for Modern Materials Surface Engineering Technology Institute of New MaterialsGuangdong Academy of ScienceGuangzhou 510650China

Environmental barrier coatings(EBCs)effectively protect the ceramic matrix composites(CMCs)from harsh engine environments,especially steam and molten ***,open pores inevitably formed during the deposition process provide the transport channels for oxidants and corrosives,and lead to premature failure of *** research work proposed a method of pressure infiltration densification which blocked these open pores in the *** results showed that it was difficult for aluminum to infiltrate spontaneously,but with the increase of external gas pressure and internal vacuum simultaneously,the molten aluminum obviously moved forward,and finally stopped infiltrating at a depth of a specific *** on the wrinkled zigzag pore model,a mathematical relationship between the critical pressure with the infiltration depth and the pore intrinsic geometry was *** infiltration results confirmed this relationship,indicating that for a given coating,a dense thick film can be obtained by adjusting the internal and external gas pressures to drive a melt infiltration.

关键词： infiltration process channel pore densification pressure assistant environmental barrier coating(EBC)

Improving WC-Co coating adhesive strength on rough substrate:Finite element modeling and experiment

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Journal of Materials Science & Technology 2020年第2期37卷 1-8页

作者： Adnan Tahir Guang-Rong Li mei-jun liu Guan-jun Yang Cheng-Xin Li Yu-Yue Wang Chang-Jiu Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an710049China

The adhesive strength in a coating-substrate system is of primary importance for the coating lifetime in ***,the underlying mechanism is not fully understood due to the complex internal structure of composite *** this study,the effect of substrate roughness on the adhesive strength of WCCo coatings was investigated by experiment and *** show that the adhesive strength is significantly affected by the *** the case of the Ra<2μm,the adhesive strength is approximately 35–46 *** the Ra is 4μm,the adhesive strength increases to nearly 60 MPa.A finite element model was developed to correlate the roughness with adhesive *** is found that the predicted values are well consistent with the experimental *** addition,with the increase of the roughness,the residual stress would be changed from concentrated state to widespread state,which decreases the critical stress to result in crack ***’s why a larger roughness can cause a higher adhesive *** study gives understanding on the mechanism of adhesive strength affected by roughness,which contributes to the parameter optimization with better performance.

关键词： Adhesive strength Roughness Lifetime Simulation XFEM Residual stress

Plasma spray-physical vapor deposition toward advanced thermal barrier coatings:a review

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Rare Metals 2020年第5期39卷 479-497页

作者： mei-jun liu Gao Zhang Yan-Hong Lu Jia-Qi Han Guang-Rong Li Cheng-Xin Li Chang-Jiu Li Guan-jun Yang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi'an 710049China

Plasma spray–physical vapor deposition(PS–PVD)is a unique technology that enables highly tailorable functional films and coatings with various rare metal elements to be *** technology bridges the gap between conventional thermal spray and vapor deposition and provides a variety of coating microstructures composed of vapor,liquid,and solid deposition *** PS–PVD technique serves a broad range of applications in the fields of thermal barrier coatings(TBCs),environmental barrier coatings(EBCs),oxygen permeable films,and electrode *** also represents the development direction of high-performance TBC/EBC preparation *** the PS–PVD technique,the composition of the deposition unit determines the microstructure of the coating and its *** coating materials are injected into a nozzle and transported into the plasma jet,the deposition unit generated by a coating material is affected by the plasma jet ***,there is no direct in situ measurement method of material transfer and deposition processes in the PS–PVD plasma jet,because of the extreme conditions of PS–PVD such as a low operating pressure of*100 Pa,temperatures of thousands of degrees,and a thin and high-velocity *** the difficulties,the transport and transformation behaviors of the deposition units were also researched by optical emission spectroscopy,observation of the coating microstructure and other *** paper reviews the progress of PS–PVD technologies considering the preparation of advanced thermal barrier coatings from the perspective of the transport and transformation behaviors of the deposition *** development prospects of new high-performance TBCs using the PS–PVD technique are also discussed.

关键词： Plasma spray–physical vapor deposition (PSPVD) Deposition unit Cross-domain behavior Deposition mechanism Thermal barrier coatings (TBCs)

Contamination of Aflatoxins in Different Kinds of Foods in China

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Biomedical and Environmental Sciences 2007年第6期20卷 483-487页

作者： jun WANG XIU-mei liu Institute of Nutrition and Food Safety Chinese Center for Disease Control and Prevention Beijing 100050 China

Objective To study the contamination of total aflatoxins （AFs） in different kinds of foods including corn, peanut, rice, walnut, and pine nut in six provinces and two municipalities in China. Methods A total of 283 samples of corn, peanut, rice, walnut and pine nut were randomly collected from local markets in Fujian, Guangdong, Guangxi, Hubei, Jiangsu, and Zhejiang provinces, as well as in Shanghai and Chongqing municipalities. The samples were ground to which acetonitrile/water solution was added. After filtering, the extract was transferred into a MycoSepTM purifying column and was pressed slowly. Then the purified liquid was derivatized with trifluoroacetic acid （TFA） and assayed using high performance liquid chromatography （HPLC）. Results AFs were detected in 70.27% of corn samples, with a mean level of 27.44 μg/kg and the highest level of 1098.36 μg/kg. In peanut, the AFs detection rate was 23.08%, with a mean level of 0.82 μg/kg and the highest level of 28.39 μg/kg. Very few rice samples with AFs were detected. The AFs levels were very low in walnut and pine nut. Conclusion Corn is the food most seriously contaminated with AFs in China. AFBI is the main aflatoxin which is found as a contaminant in foods.

关键词： Aflatoxins Contamination Foods