检索结果-南通市图书馆

Transactions of Nonferrous Metals Society of China 2018年第5期28卷 920-930页

作者： Vahid MALEKI hamid omidvar Mohammad-Reza RAHIMIPOUR Department of Mining and Metallurgical Engineering Amirkabir University of Technology (Tehran Polytechnic) Department of Ceramic Materials and Energy Research Center

Influences of gap size and cyclic-thermal-shock treatment on the mechanical properties of transient liquid phase（TLP） bonded IN-738 LC superalloy were investigated. For this purpose, TLP bonding of IN-738 LC superalloy was carried out in a vacuum furnace using powdered AMS 4777 as the filler metal. The results showed that isothermal solidified zone（ISZ） consisted of Ni solid-solution and the distribution of alloying elements was homogeneous. High hardness of HV 409 and high shear strength of 506 MPa were observed in 40 μm gap sample. Alloying elements formed γ′ precipitates and the solid-solution in the ISZ. Hardness and shear strength of bonds were reduced with increasing the gap size（in range of 40-120 μm）. The fractured surfaces of complete isothermal solidified bonds showed dimpled rupture, but athermal solidified bonds showed cleavage fracture surface. 10, 20, 30 and 40 thermal-shock cycles were applied to 80 μm gap samples, respectively. The shear strength of the bond was measured to be 268 MPa after the 40 th thermal-shock cycle. The sample with gap size of 80 μm was failed due to crack nucleation on faying surface at 45 th thermal-shock cycle. The amount of the produced brittleness due to quenching the samples in water bath was attributed to the number of thermal-shock cycles.

关键词： IN-738 superalloy TLP bonding mechanical properties cyclic-thermal-shock treatment shear strength

New insights into microstructural changes during transient liquid phase bonding of GTD-111 superalloy

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2021年第9期31卷 2703-2715页

作者： Javad ASADI Seyed Abdolkarim SAJJADI hamid omidvar Materials and Metallurgical Engineering Department Faculty of EngineeringFerdowsi University of MashhadMashhadIran Department of Materials and Metallurgical Engineering Amirkabir University of Technology(Tehran Polytechnic)TehranIran

The effects of joining temperature(TJ)and time(tJ)on microstructure of the transient liquid phase(TLP)bonding of GTD-111 superalloy were *** bonding process was applied using BNi-3 filler at temperatures of 1080,1120,and 1160℃ for isothermal solidification time of 195,135,and 90 min,*** heat treatment was also applied to all of the *** results show that intermetallic and eutectic compounds such as Ni-rich borides,Ni−B−Si ternary compound and eutectic-γcontinuously are formed in the joint region during *** increasing tJ,intermetallic phases are firstly reduced and eventually eliminated and isothermal solidification is completed as *** the increase of the holding time at all of the three bonding temperatures,the thickness of the athermally solidified zone(ASZ)and the volume fraction of precipitates in the bonding area decrease and the width of the diffusion affected zone(DAZ)*** results are also obtained by increasing TJ from 1080 to 1160℃ at tJ=90 ***,increasing the TJ from 1080 to 1160℃ leads to the faster elimination of intermetallic phases from the ***,these phases are again observed in the joint region at 1180℃.It is observed that by increasing the bonding temperature,the bonding width and the rate of dissolution of the base metal *** on these results,increasing the homogenization time from 180 to 300 min leads to the elimination of boride precipitates in the DAZ and a high uniformity of the concentration of alloying elements in the joint region and the base metal.

关键词： TLP bonding joint GTD-111 superalloy isothermal solidification microstructure homogenization

Effect of gap size on microstructure of transient liquid phase bonded IN-738LC superalloy

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2016年第2期26卷 437-447页

作者： Vahid MALEKI hamid omidvar Mohammad-reza RAHIMIPOUR Department of Mining and Metallurgical Engineering Amirkabir University of Technology (Tehran Polytechnic) Department of Ceramic Materials and Energy Research Center

In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.

关键词： IN-738LC superalloy transient liquid phase (TLP) bonding gap size complete isothermal solidification

用机械涂层技术在Ti-6Al-4V基体表面沉积HA/Ti复合涂层与功能梯度涂层的表征、磨损行为和生物相容性

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2024年第2期34卷 547-559页

作者： Mahmood JALALI BIDAKHAVIDI hamid omidvar Ali ZAMANIAN Jamshid AGHAZADEH MOHANDESI hamid JALALI Department of Materials and Metallurgical Engineering Amirkabir University of Technology(Tehran Polytechnic)Hafez AveP.O.Box 15875-4413TehranIran Department of Nanotechnology and Advanced Materials Materials and Energy Research CenterKarajIran School of Dentistry Tehran University of Medical SciencesTehranIran

采用机械涂层技术在Ti-6Al-4V基体表面沉积HA/Ti复合涂层与功能梯度涂层(FGC),对涂层进行表征,对比其磨损行为和生物相容性。制备复合涂层所用初始粉末为50%Ti(质量分数)和50%HA(质量分数)的混合粉末,而FGC分为两层,分别为75%Ti+25%HA和... 详细信息

采用机械涂层技术在Ti-6Al-4V基体表面沉积HA/Ti复合涂层与功能梯度涂层(FGC),对涂层进行表征,对比其磨损行为和生物相容性。制备复合涂层所用初始粉末为50%Ti(质量分数)和50%HA(质量分数)的混合粉末,而FGC分为两层,分别为75%Ti+25%HA和25%Ti+75%HA(质量分数)。XRD结果表明在沉积过程中没有发生相变。此外,由于原始混合粉末中存在Ti颗粒,在涂层和基体之间形成了结合良好的连续界面,特别是在功能梯度涂层样品中。磨损实验结果显示,非梯度复合涂层的摩擦因数约为0.37,在界面处发生突变,而功能梯度涂层的摩擦因数从0.32增加到0.5,在界面处发生平缓变化。磨损表面的SEM像表明涂层的主要磨损机制为磨粒磨损。生物相容性评价结果显示,FGC样品具有更好的细胞黏附和增殖能力。

关键词：机械涂层技术羟基磷灰石 Ti-6Al-4V基体功能梯度涂层摩擦因数

Characterization， wear behavior and biocompatibility of HA/Ti composite and functionally graded coatings deposited on a Ti-6Al-4V substrate by a mechanical coating technique

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2023年

作者： Mahmood JALALI BIDAKHAVIDI hamid omidvar Ali ZAMANIAN Jamshid AGHAZADEH MOHANDESI hamid JALALI Department of Materials and Metallurgical Engineering，Amirkabir University of Technology (Tehran Polytechnic) Department of Nanotechnology and Advanced Materials，Materials and Energy Research Center School of Dentistry，Tehran University of Medical Sciences

In this study， characterization， wear behavior， and biocompatibility of HA/Ti composite and functionally graded coatings (FGCs) deposited on a Ti-6Al-4V substrate by a mechanical coating technique were compared. The composite coating was produced using the initial powder mixture of 50Wt% Ti/50Wt% HA， while the FGC was deposited by two separate layers containing 75Wt%Ti/25Wt% HA and 25Wt% Ti/75Wt% HA， respectively. The XRD results exhibited no phase changes during the deposition process. Moreover， due to the presence of Ti particles in the primary powder mixtures， a continuous interface with a superior bond was formed between the coating and the substrate， especially in the samples coated by the FGCs. The wear test results of the non-graded composite coating showed a coefficient of friction (COF) of about 0.37 with an abrupt change at the interface， while the COF of the FGCs increased from 0.32 to 0.5 with a gentle change at the interface. The SEM images of the worn surfaces indicated the dominance of the abrasive wear mechanism. The biocompatibility evaluations revealed better cell attachment and proliferation of the FGC-coated samples.

关键词：

Interfacial microstructure and mechanical properties of tungsten carbide brazed joints using Ag-Cu-Zn + Ni/Mn filler alloy

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2017年第12期27卷 2638-2646页

作者： Mahyar HASANABADI Ali SHAMSIPUR Hasan NAJAFI SANI hamid omidvar Sima SAKHAEI Department of Mining and Metallurgical Engineering Amirkabir University of Technology Tehran 15875-4413 Iran

WC-Co hard metal was furnace brazed by Ag-Cu-Zn+Ni/Mn filler alloy using a tube furnace under high-purity argon at730°*** influence of brazing time and gap size of joints was *** results revealed the maximum shear strength of(156±7)MPa for samples with150μm gap size at a holding *** characterization and microstructure of the brazed joints were characterized by SEM,EDS and *** results showed that increasing the time from5to15min could provide a better chance for the liquid interlayer to flow towards the base ***,the formation of some metallic phases such as Mn3W3C at brazing time longer than15min resulted in decreased shear strength of the joint.

关键词： brazing tungsten carbide Ag alloy filler alloy microstructure wetting properties shear strength

Complementary Inequalities to Improved AM-GM Inequality

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2017年第12期33卷 1609-1616页

作者： hamid Reza MORADI Mohsen Erfanian omidvar Department of Mathematics Mashhad Branch Islamic Azad University Mashhad Iran

Following an idea of Lin, we prove that if A and B are two positive operators such that 0 〈 mI 〈 A 〈 m＇I ≤ M＇I ≤B 〈 MI, then Ф^2（A＋B/2）≤K^2（h）/（1＋（logM＇/m＇）^2/8）^2Ф^2（A#B）,and Ф^2（A＋B/2）≤K^2（h）/（1＋（logM＇/m＇）^2/8）^2（Ф（A）#Ф（B））^2,where K（h） = （h＋1）2 /4h and h = M and Ф is a positive unital linear map.

关键词： Operator inequalities positive linear maps operator norm Kantorovich inequality Wielandt inequality

Whole-exome sequencing identified a novel mutation of MLH1 in an extended family with lynch syndrome

在线全文

学校读者我要写书评

暂无评论

Genes & Diseases 2020年第4期7卷 614-619页

作者： hamid Ghaedi Samira Molaei Ramsheh Maryam Erfanian omidvar Afsaneh Labbaf Elham Alehabib Sanaz Akbari Fatemeh Pourfatemi Hossein Darvish Department of Medical Genetics School of MedicineShahid Beheshti University of Medical SciencesTehranIran Department of Medical Laboratory Technology School of Allied Medical SciencesShahid Beheshti University of Medical SciencesTehranIran Student Research Committee Department of Medical GeneticsSchool of MedicineShahid Beheshti University of Medical SciencesTehranIran Nourdanesh Institute MeymehIsfahanIran Deputy for Prevention Affairs of State Welfare Organization of Mazandaran SariIran Cancer Research Center Semnan University of Medical SciencesSemnanIran Department of Medical Genetics School of MedicineSemnan University of Medical SciencesSemnanIran

Hereditary nonpolyposis colorectal cancer or Lynch syndrome is autosomal dominant cancer predisposition syndrome characterized by early onset of colorectal cancer and neoplasia in other *** condition typically caused by germline mutations in the mismatch repair genes MLH1,MSH2,MSH6,and *** date,a considerable number of MLH1 gene mutations have been found to be associated with Lynch *** were aimed at identifying a genetic mutation in an extended Iranian family affected by Lynch syndromerelated ***,we applied whole-exome sequencing to identifying mutation in the ***,we applied Sanger sequencing to validate the candidate *** found a heterozygous novel single nucleotide deletion(c.206delG)in the exon two of the MLH1 gene in the ***,Sanger sequencing analysis showed that this mutation has segregated in all affected family *** mutation(c.206delG:p.R69fs)may create a premature stop codon followed by the formation of a truncated(p.R69fs)Mlh1 *** findings expand the mutational spectra of MLH1 gene related Lynch syndrome which is vital for screening and genetic diagnosis of the disease.

关键词： Colorectal cancer Lung cancer Mismatch repair MLH1