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Preparation and properties of C/C-SiC brake composites fabricated by warm compacted-in situ reaction

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International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 500-505页

作者： zhuan li Peng Xiao Xiang Xiong State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

Carbon fibre reinforced carbon and silicon carbide dual matrix composites（C/C-SiC） were fabricated by the warm compacted-in situ *** microstructure,mechanical properties,tribological properties,and wear mechanism of C/C-SiC composites at different brake speeds were *** results indicate that the composites are composed of 58wt%C,37wt%SiC,and 5wt%*** density and open porosity are 2.0 ***^（-3） and 10%,*** C/C-SiC brake composites exhibit good mechanical *** flexural strength can reach up to 160 MPa,and the impact strength can reach 2.5 kJ.m^（-2）.The C/C-SiC brake composites show excellent tribological *** friction coefficient is between 0.57 and 0.67 at the brake speeds from 8 to 24 m·s^（-1）.The brake is stable,and the wear rate is less than 2.02×10^（-6） cm^3·J^（-1）.These results show that the C/C-SiC brake composites are the promising candidates for advanced brake and clutch systems.

关键词： C/C-SiC ceramic matrix composites tribological properties microstructure

Preparation,Properties and Application of C/C-SiC Composites Fabricated by Warm Compacted-in situ Reaction

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Journal of Materials Science & Technology 2010年第3期26卷 283-288页

作者： Peng Xiao zhuan li Zibing Zhu Xiang Xiong State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China China Aviation Power Plant Research Institute Zhuzhou 412002 China

Carbon fibre reinforced carbon and SiC dual matrices composites （C/C-SiC） show superior tribological properties,high thermal shock resistance and good abrasive resistance,and they are promising candidates for advanced brake and clutch *** microstructure,mechanical properties,friction and wear properties,and application of the C/C-SiC composites fabricated by warm compacted-in situ reaction were *** results indicated that the composites were composed of 50-60 wt pct carbon,2-10 wt pct residual silicon and 30-40 wt pct silicon *** C/C-SiC brake composites exhibited good mechanical *** value of flexural strength and compressive strength could reach 160 and 112 MPa,*** impact strength was about 2.5 kJ·*** C/C-SiC brake composites showed excellent tribological performance,including high coefficient of friction （0.38）,good abrasive resistance （1.10 μm/cycle） and brake steadily on dry *** tribological properties on wet condition could be mostly *** silicon carbide matrix in C/C-SiC brake composites improved the wear resistance,and the graphite played the lubrication function,and right volume content of graphite was helpful to forming friction film to reduce the wear *** results showed that C/C-SiC composites fabricated by warm compacted-in situ reaction had excellent properties for use as brake materials.

关键词： C/C-SiC Ceramic-matrix composites Tribology Warm compacted-in situ reaction

Chemiluminescence determination of 20 amino acids and the mechanism study

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Chinese Chemical Letters 2010年第7期21卷 856-859页

作者： Yan Ming liu zhuan li liu College of Chemistry and Chemical Engineering Xinyang Normal UniversityXinyang 464000China

It was found that 20 amino acids could inhibit the intensity of the luminol-H_2O_2-CuSO_4 chemiluminescence *** this character,a rapid and sensitive method for the determination of 20 amino acids was developed with flow injection coupled with chemiluminescence *** the optimal conditions,the detection limits of 20 amino acids were in the range of 4.5×10^（-7）- 4.3×10^（-10） mol/L,and the relative standard deviations were less than 3.2%.The proposed method was successfully applied to drug *** possible mechanism was also discussed.

关键词： Chemiluminescence Flow injection Amino acid Mechanism study

Microstructures and mechanical behaviors of CVI-based C/C composites containing h-BN powdered additives

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Journal of Materials Science & Technology 2019年第12期35卷 2824-2831页

作者： Peng Xiao Zhichao li Zeyan liu zhuan li Bengu Zhang Jinwei li Yang li National Key Laboratory of Science and Technology for National Defence on High-strength Structural Materials Central South UniversityChangsha 410083China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China

Hexagonal boron nitride(h-BN) powders were introduced into carbon fiber preform by powder addition and subsequent combined with chemical vapor infiltration(CVI) for densification to prepare carbon fiber reinforced/carbon and boron nitride dual matrix composites(C/C-BN). Microstructures and mechanical properties of C/C composites with three different volume contents of h-BN powders were investigated in comparison to pure C/C composites. Results indicated that the introduction of h-BN powders into C/C composites significantly reduced the size of Py C and the anisotropy of thermal contraction in matrix,leading to a gradual disappearance of ring defects as the h-BN content increased. In addition, an enhanced interfacial bonding between fiber and matrix obtained due to higher-textured Py C and rougher fiber surface. Thereby, the flexural strengths and modulus of as-prepared composites decreased firstly and then increased, while the impact toughness presented a decreasing tendency as the content of BN powders increased. Furthermore, with the increasing of h-BN content, anisotropies of compressive properties were weakened, and the compressive strength of C/C-BN composites were always higher than that of pure C/C composit. However, when C/C composites modified by 13.5 vol% content of h-BN, excessive loose BN aggregates appeared in C/C-BN composites, leading to a relatively slight reduction of compressive strength.

关键词： C/C composites h-BN Pyrolytic carbon Interfacial bonding Mechanical properties

Combined Toxicity of an Environmental Remediation Residue,Magnetite Fe3O4 Nanoparticles/Cr(Ⅵ)Adduct

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Biomedical and Environmental Sciences 2017年第11期30卷 783-791页

作者： li zhuan liU Miao CHEN li Ke li Guang Zhu College of Environment and Resource Jilin UniversityChangchun 130012JilinChina Environmental Monitoring Center of Jilin Province Changchun 130011JilinChina College of Water Conservancy and Environmental Engineering Changchun Institute of TechnologyChangchun 130011JilinChina

Objective This paper aims to elucidate the combined toxicity of magnetite nanoparticles/Chromium [MNPs/Cr（Ⅵ）] adducts. Methods The HEK293 cell was exposed to either Cr（Ⅵ） or MNPs, or their adducts MNPs/Cr（Ⅵ）. The cytotoxicity was evaluated by assessing the cell viability, apoptosis, oxidative stress induction, and cellular uptake. Results The toxicity of formed adducts is significantly reduced when compared to Cr（Ⅵ） anions. We found that the cellular uptake of MNPs/Cr（Ⅵ） adduct was rare, only few particles were endocytosed from the extracellular fluid and not accumulated in the cell nucleus. On the other hand, the Cr（Ⅵ） anions entered cells, generated oxidative stress, induced cell apoptosis, and caused cytotoxicity. Conclusion The results showed minor effects of the nanoadducts on the tested cells and supported that magnetite nanoparticles could be implemented in the wastewater treatment process in which advantageous properties outweigh the risks.

关键词： Magnetite Fe3O4 Chromium Adduct Toxicity

A Comparative Toxicity Study of TiO2 Nanoparticles in Suspension and Adherent Culture Under the Dark Condition

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Chemical Research in Chinese Universities 2018年第1期34卷 44-50页

作者： CHEN like liU Miao LENG Su li zhuan College of Environment and Resources Jilin University Changchun 130012 P. R. China College of Resources and Environment Jilin Agricultural University Changchun 130118 P. R. China

The present study focused on the different acute toxicity of TiO2 nanoparticles（TiO2 NPs） towards the bacteria in suspension culture and adherent culture under the dark conditions. The study investigated the bacteria toxicity with TiO2 NPs at different concentrations（1-2000 mg/L）, sizes（10 nm, 35 nm） and specific surface areas in unit volume solution（0-224 m^2/L） characterized by the cell viability, extracellular polymeric substances（EPS） release and biofilm formation. The bacteria in adherent culture was found to be more resistant against the toxicity of TiO2 NPs compared to that in suspension culture. An NP dose and surface area dependent（rather than the size） bacterial viability was observed in suspension culture, specifically the surface area positively correlated with the toxicity of TiO2 NPs. The size of TiO2 NPs, however, played a more critical role in toxicity of TiO2 NPs in adherent culture. Therefore, the surface area dependent toxicity of TiO2 NPs is a comprehensive parameter describing the dose and size dependent toxicity of TiO2 NPs. The electron microscopic（SEM, TEM, EDX） observations suggested the EPS release and biofilm formation, during aggregation of TiO2 NPs on the bacteria after 12 h cultivation in adherent culture under the dark condition. A possible toxic mechanism could be that ＂effective surface areas＂ that directly contact with the bacterial membrane greatly contributed to the toxicity of TiO2 NPs in both suspension culture and adherent culture. Therefore, as for the possible resistance mechanism, EPS secretion and subsequent biofilm formation may protect the bacteria against the toxicity of TiO2 NPs.

关键词： Toxicity of TiO2 nanoparticle Suspension culture Adherent culture Toxic mechanism

Water vapor corrosion behavior and failure mechanism of air sprayed bi-layer Yb_(2)Si_(2)O_(7)/SiC and tri-layer Yb_(2)Si_(2)O_(7)/(SiCw-Mullite)/SiC environmental barrier coating

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Advanced Powder Materials

Advanced Powder Materials 2023年第1期2卷 15-24页

作者： Pengju Chen Peng Xiao zhuan li Yichen Wang Xian Tang Yang li School of Nuclear Science and Technology University of South ChinaHengyang 421001China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China National Key Laboratory of Science and Technology on High-strength Structural Materials Central South UniversityChangsha 410083China School of Engineering and Materials Science Queen Mary University of LondonLondon E14NSUK

To improve the corrosion resistance of Cf/SiC composites in a water vapor oxygen coupled environment,the bilayer Yb_(2)Si_(2)O_(7)/SiC and tri-layer Yb2Si2O7/(SiCw-Mullite,SM)/SiC environment barrier coatings were designed and prepared on the surface of Cf/SiC composites by chemical vapor deposition and sol-gel method united with air *** show that the mass loss of bi-layer Yb_(2)Si_(2)O_(7)/SiC coating coated samples was 17.24×10^(-3) g cm^(-2) after 200 h oxidation at 1673 K,and the average compression strength retention rate was only 79.44% due to the formation of wide penetrating ***,SiC whiskers in SM middle coating can not only increase the crack propagation resistance of mullite middle coating,but also alleviate the difference of coefficient of thermal expansion between Yb_(2)Si_(2)O_(7) outer coating and mullite middle ***,the mass loss of trilayer Yb_(2)Si_(2)O_(7)/SM/SiC coating coated samples was only 2.93×10^(-3) g cm^(-2) after 200 h oxidation at 1673 K,and the average compression strength retention rate was up to 98.79%.

关键词： Yb_(2)Si_(2)O_(7)/SM/SiC EBCs Water Corrosion Mechanism

Expressions of Poly(ADP-ribose) Glycohydrolase(PARG) and Membrane Type 1 Matrix Metalloproteinase(MT1-MMP) in Colorectal Carcinoma

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Chinese Journal of Cancer Research 2010年第3期22卷 186-193页

作者： Xian li Guang-jie Duan Ya-lan Wang N. Jasmine Fauzee Qiao-zhuan li Department of Pathology Molecular Medicine and Cancer Research Center Chongqing MedicalUniversity Chongqing 400016 China Institute of Pathology Southwest Hospital Third Military Medical University Chongqing400038 China

Objective：To investigate the significance of Poly（ADP-ribose） glycolhydrolase（PARG） and membrane type 1 matrix metalloproteinase（MT1-MMP） expressions in human colorectal ***：Immunohistochemical staining for PARG and MT1-MMP was carried out on colorectal adenoma-carcinoma tissue microarrays containing normal colorectal mucosae,adenoma,adenoma with malignant transformation and adenocarcinoma（total 130 specimens）.The expressions of PARG and MT1-MMP in the GLTN [Gallotannin]-treated and GLTN-untreated lovo cells were detected by Western ***：PARG expression in adenocarcinoma（83.1%） and adenoma with malignant transformation（66.7%） was significantly higher than that in normal colorectal mucosa（10%） and adenoma（10.5%）.Expression of MT1-MMp in normal colorectal mucosa and adenoma was negative,while the expression in adenocarcinoma（80.3%） and adenoma with malignant transformation（72.2%） was *** expressions of PARG and MT1-MMP in adenocarcinoma with metastasis and in late tumor stages were significantly higher than those in adenocarcinoma with no metastasis and in early tumor ***,PARG expression shows a positive correlation with the expression of *** expressions of PARG and MT1-MMP in GLTN-treated lovo cells were weaker than that in GLTN-untreated lovo ***：The expression of PARG was probably related to the development of colorectal *** may play an important role for the regulation of MT1-MMP expression in colorectal carcinoma.

关键词： PARG MT1-MMP Colorectal carcinoma Tissue microarray Immunohistochemistry

Sepiolite:A new component suitable for 380 km/h high-speed rail brake pads

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Advanced Powder Materials

Advanced Powder Materials 2024年第4期3卷 36-46页

作者： Jiaqi Wu zhuan li Guoyuan Wen Zonglong Gao Ye li Yang li Peng Xiao Powder Metallurgy Research Institute Central South UniversityChangsha 410083China

To enhance the high-temperature adaptability of copper-based composite materials and C–C/SiC discs,this article innovatively introduces a method of replacing graphite with sepiolite,resulting in the successful fabrication of samples with exceptional mechanical and friction *** results reveal that moderate incorporation(less 6%)of sepiolite provides a particle reinforcement effect,resulting in an improvement of mechanical ***,the addition of sepiolite causes a change in the traditional saddle-shaped friction curve due to high temperature ***,the primary advantage of sepiolite lies in its superior abrasion resistance,evident in the increased friction coefficient and altered wear mechanisms with higher sepiolite *** wear resistance is optimal at 200 Km/h(400℃).Particularly,the unique composition of the friction layer(outermost layer:a composite film consisting of B2O3,sepiolite,graphite,and metal oxide films;intermediate layer:metal oxide films)plays a pivotal role in improving friction ***,there are significant optimizations in the GA algorithm,especially GA-GB model has the best prediction effect on the maximum friction temperature.

关键词： Lubrication-wear Sepiolite-graphite High-speed rail brake pads Mechanisms Friction layer Prediction of temperature