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Surface Top Graphology,Corrosion and Microhardness of Oxygen Diffusion Hardened Pure Titanium Alloy TA4 after Laser Surface melting

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稀有金属材料与工程 2011年第S4期40卷 185-189页

作者： Chen Changjun,Zhang Min,Su Yanzhan,Zhang Shichang,Zhou Jialin Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Laser Processing Research Center,College of Materials and Metallurgy,Wuhan University of Science& Technology,Wuhan 430081,China Wuhan Univ Sci & Technol Laser Proc Res Ctr Key Lab Ferrous Met & Resources Utilizat Minist EducColl Mat & Met Wuhan 430081 Peoples R China

In the oxygen diffusion hardened condition,untreated and laser surface melted pure titanium alloy (TA4) by Nd:YAG pulsed laser,are hardened at temperatures of 650 to 700℃ with the end result being a passive,mechanically stable,abrasion resistant oxide ceramic rutile surface *** thickness of this surface layer depends on the time,temperature,and the microstructure of the Ti *** paper describes the results of x-ray diffraction analysis,scanning electron microscope (SEM),microhardness measurements,and corrosion resistance measurements of hardened pure and laser treated Ti *** oxygen diffusion hardened titanium alloy after laser surface melted samples (L-TA4) had a more pronounced grain structure and significantly higher roughness values than the untreated pure TA4 (U-TA4)*** L-TA4 samples also exhibited at least equivalent corrosion behavior and a definite increase in surface hardness compared to the U-TA4 *** results of this work suggest that laser surface melting plays a key role for effective oxygen diffusion hardening at 650-700℃ for pure and laser treated pure Ti alloys.

关键词： oxygen diffusion harden (ODH) titanium alloy laser surface melting corrosion

Characterization of In-situ Titanium Matrix Composites Prepared by Laser melting Deposition

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稀有金属材料与工程 2011年第S3期40卷 33-37页

作者： Zhang Yongzhong1, Sun Jingchao1, Huang Can1, Li Guowei2 1 General Research Institute for Non-ferrous Metals, Beijing 100088, China 2 Nantong Entry-Exit Inspection and Quarantine Bureau, Nantong 226005, China Gen Res Inst Nonferrous Met Beijing 100088 Peoples R China Nantong Entry Exit Inspect & Quarantine Bur Nantong 226005 Peoples R China

Preliminary characterization of microstructure and mechanical properties of (TiB+TiC)/TC4 and TiC/Ti60 in-situ titanium matrix composites prepared by laser melting deposition is reported in this paper. The results indicate that in-situ reaction occurred during laser melting deposition of coaxially fed mixed powders from TC4 and B4C with formation of form TiB and TiC reinforcement. For TiC/Ti60 composites, there are some un-melted TiC particles and re-solidified TiC particles appeared as discontinuous chain-like morphology. Reinforcements of TiB and TiC with fraction about 25 vol% were formed with feeding 5 wt% B4C. The morphology of TiB tended to be needle-like and prismatic, while TiC appeared as granular. Small amount of un-reacted B4C with reduced size remained within the composites. A thin skull of reaction product formed around the un-reacted B4C weakened its interface bonding with the titanium alloy matrix, thus resulting in less outstanding properties of the composites. Under 600 ℃, the ultimate tensile strength of the TiCP (5wt%)/Ti60 composites was 60 MPa higher than that of Ti60 alloy, following with decreased elongation.

关键词： titanium matrix composites in-situ reaction laser melting deposition microstructure properties

Heating and melting mechanism of stainless steelmaking dust pellet in liquid slag

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Journal of Central South University of Technology 2007年第1期14卷 32-36页

作者：彭及唐谟堂彭兵余笛 J. A. KOZINSKI 唐朝波 School of Metallurgical Science and Engineering Central South University School of Information Science and Engineering Central South University Department of Metallurgical Engineering McGill University3610 University StreetMontrealH3A 2B2Canada

The heating and melting mechanisms of the pellets immersed in liquid slag were investigated, and the effect of the pellet heating and the melting conditions were studied. The results show that the dust component in the pellet is melted from the surface and no metallic elements are melted before the dust component, the time for the pellet completely melted is reduced as the iron powder content increases since the metallic iron has high thermal conductivity. These are four stages of heating and melting of pellet in liquid slag, they are the growth and melt of solid slag shell, penetration of liquid slag, dissolving of dust component and melting of reduced metals. The lifetime of the solid slag shell is in the range of 7-16 s and increasing the pre-heating temperature of the pellet and the slag temperature can shorten the slag shell lifetime. The time for the dust component in the pellet to be melted completely is in the range of 20-45 s and increasing the pre-heating temperature, especially in the range of 600-800 ℃, can obviously reduce the melting time. A higher slag temperature can also improve the pellet melting and the melting time is reduced by 10-15 s when the slag temperature is increased from 1 450 to 1 550 ℃. The pellet with higher content of iron powder is beneficial to the melting by improving the heat conductivity.

关键词： heating melting mechanism stainless steelmaking dust recycling

High resolution melting real-time PCR detect and identify filarial parasites in domestic cats

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Asian Pacific Journal of Tropical Medicine 2018年第12期11卷 682-687页

作者： Darawan Nonsaithong Supit Yotmek Somsri Yotmek Hathai Nochote Sirichit Wongkamcha Sittiruk Roytrakul Usa Lek-Uthai Master of Science (Public Health) Program in Infectious Diseases and Epidemiology Faculty of Graduate Studies Mahidol University Department of Parasitology and Entomology Faculty of Public Health Mahidol University Center for Disease Control Vector Borne Disease Control Center 11.3 Surat Thani Province Department of Parasitology Faculty of Medicine Siriraj Hospital Mahidol University National Center for Genetic Engineering and Biotechnology (BIOTEC) National Science and Technology Development Agency (NSTDA)

Objective: To detect and identify filarial parasites in dried blood spots(DBS) collected from domestic cats using high resolution melting real-time PCR(HRM RT-PCR). Methods: A total of 208 DBS were collected from domestic cats in a brugian filariasis endemic areas in Surat Thani Province, southern Thailand. Microfilariae were found in 9 blood slides using Giemsa-stained thick blood film. The extracted DNA from blood spot volumes of 10 and 20 μL DBS with positive filarial parasites in cats were performed using HRM RT-PCR method. The primers were designed based on the partial mitochondrial 12S rRNA gene for identifying Brugia malayi, Brugia pahangi, Dirofilaria immitis. All purified samples were then detected. Results: Using different volumes of 10 μL and 20 μL DBS could easily distinguish filarial parasites and showed similar results. PCR amplicons of Brugia malayi, Brugia pahangi and Dirofilaria immitis were determined at melting peak(temperature) of 75.70℃, 77.46 ℃, and 73.56 ℃, respectively. All 9 positive DBS samples showed positive Brugia pahangi and similar nucleotide sequences. Conclusions: This HRM RT-PCR method is able to diagnose, identify and discriminate filarial parasites collected from DBS, which is simple and inexpensive compared with other probe-based genotyping methods. Furthermore, this method is useful to survey, prevent and control filariasis.

关键词： High resolution melting analysis Dried blood spot Brugia malayi Brugia pahangi Dirofilaria immitis

UNUSUAL CRYSTALLIZATION AND melting PROCESSES OF AN OPTICALLY ACTIVE POLYOLEFIN:ISOTACTIC POLY((S)-4-METHYL-HEXENE-1)

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Chinese Journal of Polymer Science 2005年第2期23卷 165-170页

作者： Annamaria Buono JrjengRuan AnnetteThierry Peter Neuenschwander Bernard Lotz Institut Charles Sadron and Dipartimento di Chimica Universita di Napoli Federico ⅡVia Cynthia 5NapoliItalyInstitut Charles Sadron(CNRS-ULP)6Rue Boussingault67083 StrasbourgFranceInstitut Charles Sadron(CNRS-ULP)6Rue Boussingault67083 StrasbourgFranceInstitute for PolymersETH ZentrumCNB E 93.2Universitaetstrasse 6CH-8092 ZurichSwitzerlandInstitut Charles Sadron(CNRS-ULP)6Rue Boussingault67083 StrasbourgFrance

Polyolefins that bear a chiral side chain(typically an isobutyl group)experience a so-called macromolecularamplification of chirality:the chiral side-chain induces a slight preference for either tg or tg(?) main chain ***slight conformational bias is amplified cooperatively along the chain,and results in preferred chirality of the main chainhelical *** a result,these polymers display a liquid-crystal(LC)phase both in solution and,in the melt as atransient phase on the way to *** existence of two processes(melt-LC and LC-crystal transitions)results inunconventional behaviors that were first analyzed by Pino and collaborators back in *** polymers also offer a meansto test the structural consequences of recently introduced crystallization *** schemes postulate the formation of atransient liquid-crystal phase as a general scheme for polymer crystallization.

关键词： Liquid crystalline polyolefins Crystallization melting Amplification of chirality.

Inclusions in melting process of titanium and titanium alloys

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China Foundry 2019年第4期16卷 223-231页

作者： Meng-jiang Cen Yuan Liu Xiang Chen Hua-wei Zhang Yan-xiang Li Department of Materials Engineering School of Materials Science and Engineering Tsinghua University Beijing 100084 China Key Laboratory for Advanced Materials Processing Technology (MOE) Tsinghua University Beijing 100084 China

This paper summarizes melting methods of titanium and titanium alloy, such as vacuum arc melting(VAR) and electron beam cold hearth melting(EBCHM), and the related inclusions formed when using these melting methods. Low-density inclusions are resulted from contamination of air, and high-density inclusions are caused by refractory elements. The formation process of inclusions was analysed. The removal mechanism of different kinds of inclusions was specified. Low-density inclusions are removed mainly by resolving. This is a comprehensive process containing reaction diffusion. The resolving rate of high-density inclusions is so low that these inclusions are mainly removed by sedimentation. The experiments and physical models of inclusions are detailed. In various melting methods, vacuum arc melting is prominent. However, this method cannot remove inclusions effectively, which usually results in repeat melting. Electron beam cold hearth melting has the best ability of removing inclusions. These results can provide instructions to researchers of titanium and titanium alloys.

关键词： titanium inclusions vacuum arc melting electron beam cold hearth melting

Thermal Analysis of melting Occurring Inside a Finned Rectangular Enclosure Equipped with Discrete Pulsed Protruding Heat Sources

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Fluid Dynamics & Materials Processing 2022年第5期18卷 1539-1549页

作者： Brahim Amahan Hamid El Qarnia Ali El Afif Faculty of Sciences Department of PhysicsLaboratory of Innovation in Sciences Technology and ModelingChouaib Doukkali UniversityEl JadidaMorocco Faculty of Sciences Semlalia Fluid Mechanics and Energetic LaboratoryDepartment of PhysicsCadi Ayyad UniversityMarrakeshMorocco

This paper numerically investigates the effect of the location of a horizontal fin on the melting of a phase change material(PCM)inside a rectangular enclosure heated by multiple discrete pulsed protruding heat *** fin and the phase change material filling the enclosure store the thermal energy extracted from the heat sources,in sensible and latent *** heat sources are assumed to simulate electronic components undergoing a superheating technical *** extracting heat from the electronics,the PCM plays the role of a heat *** analyze the thermal behavior and predict the cooling performance of the proposed cooling system,we derive a nonlinear mathematical model based on mass,momentum and energy conservation *** numerical investigations are conducted to quantify the influence of the fin position on the thermal behavior and the cooling performance of the heat *** include the transient maximum temperature occurring inside the heat sources and the liquid volume.A comparison between our numerical results and experimental data selected from the literature shows a good *** main conclusion is that the presence of the fin leads to a slight increase in the melting time.

关键词： Phase change material melting heat transfer pulsed heating electronics cooling heat storage fin

Corneal graft melting: a systematic review

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International Journal of Ophthalmology(English edition) 2020年第3期13卷 493-502页

作者： Bin-Bin Zhu Jie Zhou Jiao Zheng Yue Zhang Ting Wan Xiao-Dan Huang Lin Lin Xiu-Ming Jin Eye Center the Affiliated Second HospitalSchool of MedicineZhejiang UniversityHangzhou 310009Zhejiang ProvinceChina

Corneal graft melting is a severe complication of *** review is to summarize the incidence,the pathogenesis,the risk factors,the prognosis and the prevention of corneal graft melting after *** systematically searched PubMed,Web of Science and WanFang database to retrieve potentially eligible articles about relevant clinical reports and animal *** read the full texts to identify eligible *** selection of studies and data extraction were performed independently by two *** conclusion,the pathogenesis of corneal graft melting is complicated,and many risk factors are closely related to corneal graft *** of pathogenesis and risk factors of corneal graft melting can facilitate the development of targeted therapies to better guide clinical practice.

关键词： corneal graft melting keratoplasty incidence complication

A Quantum Mechanical Analysis of the melting Points of Transition Metals——A Novel Hypothesis of Metallic Bond

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Science China Chemistry 1994年第7期37卷 769-777页

作者：胡志彬胡贤君 Department of Chemistry Beijing Normal University Physicochemical Institute of Nuclear Engineering

From a quantum mechanical analysis of the melting points of the transition elements the authors put forward a hypothesis that the valence electrons are moving between the occupied orbitals and the empty orbitals as well as they are playing a role as "free electrons" moving in the crystal space. Both of these processes constitute a mixed type of metallic bonding. By means of this hypothesis a relation (2/1)m_p/(n_en_o+n_er_a) has been recognised and these values must be crowded in a narrow numerical field. By calculation they are found to be 1.006士0.103 in *** have also been made on m_p/(n_en_o+n_er_e) and it is found that the ratios of the average values of the three transition periods are 1:1.155:*** are in lmost exact accord with the ratios of the momentum of these periods,i.e.(n+(2/1l(l+1))).By assuming that "free electrons" are responsible essentially for the electro-and thermo-conductions, the average values of (2/1)m_pQ’(or Q") re found to be 1.66士0.26 and 1.65士0.29 for these conductions respectively. Howev-er, there exist regularities in their deviations,implying that the two metallic constitutions must play a coop-erative role in these transfers, and under the ordinary temperatures (between ambient and m. p.)"free elec-trons" play an essential role. At last, the authors have inferred the probable mechanism of superconduc-tivity.

关键词： metallic bond melting points of metals metallic conduction thermal conduction supercon-ductivity