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Novelty phase synthesis mechanism and morphology in resin-bonded Al–Al2O3–TiO2 composites at high temperatures under flowing N2

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1177-1185页

作者： yang Sun Yong Li Li-xin Zhang Shi-ming Li ming-wei yan Jia-lin Sun School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Sinosteel Refractory Co. Ltd. Henan 471039China Beijing Cisri-nmt Environmental Science and Technology Co. Ltd. Beijing 100083China

An Al–AlN core–shell structure is beneficial to the performance of Al–Al2O3 composites. In this paper, the phase evolution and microstructure of Al–Al2O3–TiO2 composites at high temperatures in flowing N2 were investigated after the Al–AlN core–shell structure was created at 853 K for 8 h. The results show that TiO2 can convert Al into Al3Ti(~1685 K), which reduces the content of metal Al and rearranges the structure of the composite. Under N2 conditions, Al3Ti is further transformed into a novelty non-oxide phase, TiCN. The transformation process can be expressed as follows: Al3Ti reacts with C and other carbides(Al4C3 and Al4O4C) to form TiCx(x < 1). As the firing temperature increases, Al3Ti transforms into a liquid phase and produces Ti(g) and TiO(g). Finally, Ti(g) and TiO(g) are nitrided and solid-dissolved into the TiCx crystals to form a TiCN solid solution.

关键词： aluminum titanium oxide alloys titanium carbonitride

Formation mechanism of calcium hexaluminate

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International Journal of Minerals,Metallurgy and Materials 2016年第10期23卷 1225-1230页

作者： Jun-hong Chen Hai-yang Chen ming-wei yan Zheng Cao Wen-jun Mi School of Materials Science and Engineering University of Science and Technology Beijing

To investigate the formation mechanism of calcium hexaluminate（CaAl_（12）O_（19）, CA_6）, the analytically pure alumina and calcia used as raw materials were mixed in CaO/Al_2O_3 ratio of 12.57：137.43 by mass. The raw materials were ball-milled and shaped into green specimens, and fired at 1300-1600°C. Then, the phase composition and microstructure evolution of the fired specimen were studied, and a first principle calculation was performed. The results show that in the reaction system of CaO and Al_2O_3, a small amount of CA_6 forms at 1300°C, and greater amounts are formed at 1400°C and higher temperatures. The reaction is as follows： CaO ·2Al_2O_3（CA_2）＋ 4Al_2O_3 → CA_6. The diffusions of Ca^（2＋） in CA_2 towards Al_2O_3 and Al^（3＋） in Al_2O_3 towards CA_2 change the structures in different degrees of difficulty. Compared with the difficulty of structural change and the corresponding lattice energy change, it is deduced that the main formation mechanism is the diffusion of Ca^（2＋） in CA_2 towards Al_2O_3.

关键词： calcium hexaluminate microstructural evolution first principle formation mechanisms

Reaction behavior of trace oxygen during combustion of falling FeSi75 powder in a nitrogen flow

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 959-965页

作者： Bin Li Jun-hong Chen Peng Jiang ming-wei yan Jia-lin Sun Yong Li School of Materials Science and Engineering University of Science and Technology Beijing

To explore the reaction behavior of trace oxygen during the flash combustion process of falling FeSi75 powder in a nitrogen flow, a flash-combustion-synthesized Fe-Si;N;sample was heat-treated to remove SiO;. The samples before and after the treatment were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and the formation mechanism of SiO;was investigated. The results show that SiO;in the Fe-Si;N;is mainly located on the surface or around the Si;N;particles in dense areas, existing in both crystalline and amorphous states; when the FeSi75 particles, which are less than 0.074 mm in size, fell in up-flowing hot N;stream, trace oxygen in the N;stream did not significantly hinder the nitridation of FeSi75 particles as it was consumed by the surface oxidation of the generated Si;N;particles to form SiO;. At the reaction zone, the oxidation of Si;N;particles decreased the oxygen partial pressure in the N;stream and greatly reduced the opportunity for FeSi75 particles to be oxidized into SiO;; by virtue of the SiO;film developed on the surface, the Si;N;particles adhered to each other and formed dense areas in the material.

关键词： silicon nitride combustion synthesis oxygen atmosphere

A new synthetic route to MgO–MgAl2O4–ZrO2 highly dispersed composite material through formation of Mg5Al2.4Zr1.7O12 metastable phase: synthesis and physical properties

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International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 332-341页

作者： Peng Jiang Guo-xiang Yin ming-wei yan Jia-lin Sun Bin Li Yong Li School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing Beijing 100083 China

Mg_5Al_(2.4)Zr_(1.7)O_(12) metastable phase was successfully synthesized from analytical-grade Mg O,α-Al_2O_3,MgAl_2O_4,and ZrO_2 under an N_2 *** sintering temperature was varied from 1650 to 1780°C,and the highest amount of Mg_5Al_(2.4)Zr_(1.7)O_(12) appeared in the composite material when the sintering temperature was 1760°*** to our research of the formation mechanism of Mg_5Al_(2.4)Zr_(1.7)O_(12),the formation and growth of MgAl_2O_4 dominated when the temperature was not higher than 1650°*** the temperature was higher than 1650°C,MgO and ZrO_2 tended to diffuse into MgAl_2O_4 and the Mg_5Al_(2.4)Zr_(1.7)O_(12) solid solution was *** the temperature reached 1760°C,the formation of Mg_5Al_(2.4)Zr_(1.7)O_(12) was *** effect of Mg Al_2O_4 spinel crystals was also studied,and their introduction into the composite material promoted the formation and growth of Mg_5Al_(2.4)Zr_(1.7)O_(12).A highly dispersed MgO–Mg Al_2O_4–ZrO_2 composite material was prepared through the decomposition of the Mg_5Al_(2.4)Zr_(1.7)O_(12) metastable *** as-prepared composite material showed improved overall physical properties because of the good dispersion of MgO,MgAl_2O_4,and ZrO_2 phases.

关键词： metastable phases formation mechanisms composite materials refractory materials synthesis physical properties

Morphology characterization of periclase–hercynite refractories by reaction sintering

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International Journal of Minerals,Metallurgy and Materials 2015年第11期22卷 1219-1224页

作者： Peng Jiang Jun-hong Chen ming-wei yan Bin Li Jin-dong Su Xin-mei Hou School of Materials Science and Engineering University of Science and Technology Beijing Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing

A periclase？hercynite brick was prepared via reaction sintering at 1600℃for 6 h in air using magnesia and reaction-sintered hercynite as raw materials. The microstructure development of the periclase-hercynite brick during sintering was investigated using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. The results show that during sintering, Fe^2＋, Fe^3＋ and Al^3＋ ions in hercynite crystals migrate and react with periclase to form（Mg1-xFex）（Fe2-yAly）O4 spinel with a high Fe/Al ratio. Meanwhile, Mg^2＋ in periclase crystals migrates into hercynite crystals and occupies the oxygen tetrahedron vacancies. This Mg^2＋ migration leads to the formation of（Mg1-uFeu）（Fe2-vAlv）O4 spinel with a lower Fe/Al ratio and results in Al3＋ remaining in hercynite crystals. Cation diffusion between periclase and hercynite crystals promotes the sintering process and results in the formation of a microporous structure.

关键词： refractories periclase hercynite sintering morphology diffusion

Morphology of α-Si_3N_4 in Fe–Si_3N_4 prepared via flash combustion

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International Journal of Minerals,Metallurgy and Materials 2015年第12期22卷 1322-1327页

作者： Bin Li Jun-hong Chen Jin-dong Su ming-wei yan Jia-lin Sun Yong Li School of Materials Science and Engineering University of Science and Technology Beijing

The state and formation mechanism of α-Si3N4 in Fe-Si3N4 prepared by flash combustion were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that α-SiaN4 crystals exist only in the Fe-Si3N4 dense areas. When FeSi75 particles react with N2, which generates substantial heat, a large number of Si solid particles evaporate. The product between Si gas and N2 is a mixture of α-Si3N4 and β-Si3N4. At the later stage of the flash combustion process, α-Si3N4 crystals dissolve and reprecipitate as α-Si3N4 and the β-Si3N4 crystals grow outward from the dense areas in the product pool. As the temperature decreases, the α-SiaN4 crystals cool before transforming into β-SiaN4 crystals in the dense areas of Fe-Si3N4. The phase composition of flash-combustion-synthesized Fe-SiaN4 is controllable through manipulation of the gas-phase reaction in the early stage and the α→β transformation in the later stage.

关键词： silicon nitride combustion synthesis morphology crystal growth

In situ reaction mechanism of MgAlON in Al–Al2O3–MgO composites at 1700°C under flowing N2

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 1061-1066页

作者： Shang-hao Tong Yong Li ming-wei yan Peng Jiang Jia-jia Ma Dan-dan Yue School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

The Al–AlO–MgO composites with added aluminum contents of approximately 0wt%, 5wt%, and 10wt%, named as M, M, and M, respectively, were prepared at 1700°C for 5 h under a flowing Natmosphere using the reaction sintering method. After sintering, the Al–AlO–MgO composites were characterized and analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results show that specimen Mwas composed of MgO and MgAlO. Compared with specimen M, specimens Mand Mpossessed MgAlON, and its production increased with increasing aluminum addition. Under an Natmosphere, MgO, AlO, and Al in the matrix of specimens Mand Mreacted to form MgAlON and AlN-polytypoids, which combined the particles and the matrix together and imparted the Al–AlO–MgO composites with a dense structure. The mechanism of MgAlON synthesis is described as follows. Under an Natmosphere, the partial pressure of oxygen is quite low; thus, when the Al–AlO–MgO composites were soaked at 580°C for an extended period, aluminum metal was transformed into AlN. With increasing temperature, AlOdiffused into AlN crystal lattices and formed AlN-polytypoids; however, MgO reacted with AlOto form MgAlO. When the temperature was greater than(1640 ± 10)°C, AlN diffused into AlOand formed spinel-structured AlON. In situ MgAlON was acquired through a solid-solution reaction between AlON and Mg AlOat high temperatures because of their similar spinel structures.

关键词： composites metal aluminum nitrogen atmosphere magnesium aluminum oxynitride reaction mechanism

Retinal neovascularization induced by mutant Vldlr gene inhibited in an inherited retinitis pigmentosa mouse model:an in-vivo study

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International Journal of Ophthalmology(English edition) 2021年第7期14卷 990-997页

作者： wei-ming yan Pan Long Mei-Zhu Chen Dong-Yu wei Jian-Cong Wang Zuo-ming Zhang Lei Zhang Tao Chen Department of Ophthalmology the 900^(th)Hospital of Joint Logistic Support Forceo of PLA(Clinical Medical College of Fujian Medical UniversityDongfang Hopsital Affiliated to Xiamen University)Fuzhou 350025Fujian ProvinceChina Center of Clinical Aerospace Medicine Air Force Medical UniversityXi’an 710032Shaanxi ProvinceChina Department of Ophthalmology the West General Hospital of Chinese PLAChengdu 610083Sichuan ProvinceChina BeiJing HealthOLight Technology Co. Ltd.Beijing 10010China Shaanxi Eye Hospital Xi’an People’s Hospital(Xi’an Fourth Hospital)Affiliated Guangren HospitalSchool of MedicineXi’an Jiaotong UniversityXi’an 710004Shaanxi ProvinceChina

AIM:To explore whether the retinal neovascularization(NV)in a genetic mutant mice model could be ameliorated in an inherited retinitis pigmentosa(RP)mouse,which would help to elucidate the possible mechanism and prevention of retinal NV diseases in ***:The Vldlr^(-/-)mice,the genetic mutant mouse model of retinal NV caused by the homozygous mutation of Vldlr gene,with the rd1 mice,the inherited RP mouse caused by homozygous mutation of Pde6b gene were *** of the above two mice led to the birth of the F1 hybrids,further inbreeding of which gave birth to the F2 *** ocular genotypes and phenotypes of the mice from all generations were examined,with the F2 offspring grouped according to the ***:The rd1 mice exhibited the RP phenotype of outer retinal degeneration and loss of retinal *** Vldlr^(-/-)mice exhibited the phenotype of retinal NV obviously shown by the fundus fluorescein *** F1 hydrides,with the heterozygote genotype,exhibited no phenotypes of RP or retinal *** F2 offspring with homozygous genotypes were grouped into four *** were the F2-Ⅰmice with the wild-type Pde6b and Vldlr genes(Pde6b~(+/+)-Vldlr~(+/+)),which had normal ocular phenotypes;the F2-Ⅱmice with homozygous mutant Vldlr gene(Pde6b~(+/+)-Vldlr^(-/-)),which exhibited the retinal NV phenotype;the F2-Ⅲmice with homozygous mutant Pde6b gene(Pde6b^(-/-)-Vldlr~(+/+)),which exhibited the RP ***,the F2-Ⅳmice with homozygous mutant Vldlr and Pde6b gene(Pde6b^(-/-)-Vldlr^(-/-))showed only the RP phenotype,without the signs of retinal ***:The retinal NV can be inhibited by the RP phenotype,which implies the role of a hyperoxic state in treating retinal NV diseases.

关键词： retinitis pigmentosa retinal neovascularization Pde6b gene Vldlr gene photoreceptor

γδ T Cells Contribute to the Outcome of Murine Fulminant Viral Hepatitis via Effector Cytokines TNF-α and IFN-γ

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Current Medical Science 2018年第4期38卷 648-655页

作者： Di WU wei-ming yan Hong-wu WANG Da HUANG Xiao-ping LUO Qin NING Department of Infectious Disease Institute of Infectious Disease Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China Department of Pediatrics Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China

The mechanisms involved in virus-induced severe hepatitis have not been fully elucidated. In this study, we investigated the role of gamma delta T cell receptors （γδ） T cells in the pathogenesis of fulminant viral hepatitis （FVH） induced by murine hepatitis virus strain 3 （MHV-3）. The model of FVH was established by intraperitoneal injection of MHV-3 into Balb/cJ mice. The survival days of mice, and the serum levels of alanine aminotransferase （ALT） and aspartate aminotransferase （AST） were examined. The proportions of γδ T cells in blood, spleen and liver, and cytokines secreted by hepatic γδ T cells were analyzed by flow cytometry. The function of hepatic γδ T cells was examined by cytotoxicity assay. Balb/cJ mice died in 3 to 6 days post MHV-3 infection, with severe hepatic necrosis and significant augmentation of serum ALT and AST levels. The proportions of γδ T cells in blood, spleen and liver were significantly increased post MHV-3 infection, while those of the early activating molecule CD69-expressing γδ T cells and productions of cytokines tumor necrosis factor-alpha （TNF-α） and interferon-y （IFN-3,） increased remarkably in the liver. These highly activated liver γδ T cells were cytotoxic to MHV-3-infected hepatocytes in vitro and this effect of liver γδ T cells against hepatocytes might involve the TNF-α and IFN-γ pathway. These results demonstrated that γδ T cells might contribute to the pathogenesis of MHV-3-induced FVH through the effector cytokines TNF-α and IFN-γ. Key words： fulminant viral hepatitis; murine hepatitis virus strain 3; gamma delta T cell receptors T cells; tumor necrosis factor-a; interferon-α

关键词： fulminant viral hepatitis murin-e hepatitis virus strain 3 gamma delta Tcellreceptors T cells tumor necrosis factor-α interferon-γ