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Role of Ag microalloying on glass forming ability and crystallization kinetics of ZrcoAgAlNi amorphous alloy

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chinese Physics B 2021年第1期30卷 471-476页

作者： A Surendar K Geetha c rajan M Alaazim Department of Pharmacology Saveetha Dental College and HospitalSaveetha Institute of Medical and Technical SciencesChennaiIndia cSE Excel Engineering CollegePallakapalayamKomarapalayam637303India IT K S Rangasamy College of Technology TiruchengodeNamakkalTamil Nadu 637215India Faculty of Engineering Universitas Muhammadiyah Surakarta(UMS)Indonesia

Bulk metallic glasses(BMGs) with new chemical compositions(ZrcoAgAlNi) were fabricated and the effects of Ag minor addition on the glass forming ability(GFA) and crystallization kinetics were studied. The x-ray diffraction(XRD) test was applied to identify the amorphousness of BMGs or possible crystalline phases. Using differential scanning calorimeter(DSc), the thermal stability and crystallization kinetics under a non-isothermal condition at the different heating rates were studied. considering the heating rate dependency of glass transition and crystallization kinetics, the activation energy was evaluated and measured for the mentioned processes. It was revealed that the rise in Ag content led to the decrease in activation energy for glass transition, while the activation energy for crystallization increased. The thermal stability and GFA were also studied and it was found that the Ag addition strongly affected the inherent features of BMGs. With the increase in Ag content, the atomic mobility and structural rearrangement changed in the material and consequently, the GFA and thermal stability were significantly improved.

关键词： bulk metallic glass materials design crystallization kinetics glass forming ability

Developments in Processing of Functionally Gradient Metals and Metal–ceramic composites:A Review

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Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 825-838页

作者： T.P.D.rajan B.c.Pai Materials Science and Technology Division CSIR-National Institute for Interdisciplinary Science and TechnologyIndustrial Estate PO

Functionally gradient/graded materials （FGMs）, an emerging new class of materials, are the outcome of the recent innovative concepts in materials technology. FGMs are in their early stages of evolution and expected to have a strong impact on the design and development of new components and structures with better performance. FGMs exhibit gradual transitions in the microstructure and/or the composition in a specific direction, the presence of which leads to variation in the functional performance within a part. The presence of gradual transitions in material composition in FGMs can reduce or eliminate the deleterious stress concentrations and result in a wide gradation of physical and/or chemical properties within the material. Functionally graded metal-ceramic composites are also getting the attention of the researchers. Among the fabrication routes for FGMs such as chemical vapour deposition, physical vapour deposition, the sol-gel technique, plasma spraying, molten metal infiltration, self propagating high temperature synthesis, spray forming, centrifugal casting, etc., the ones based on solidification route are preferred for FGMs because of their economics and capability to make large size products. The present paper discusses and compares various solidification processing tech- niques available for the fabrication of functionally gradient metals and metal-ceramic composites and lists their properties and possible applications. The other processing methods are briefly described.

关键词： Functionally gradient materials Solidification Aluminium centrifugal casting Infiltration

correlation of field and experimental test data of wear in heavy commercial vehicle brake liners

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Friction 2017年第1期5卷 56-65页

作者： B.SURyA rajan M.A.SAI BALAJI c.VELMURUGAN Department of Mechanical Engineering BS Abdur Rahman University Chennai 600048 India Department of Mechanical Engineering Panimalar Institute of Technology Chennai 600048 India

The correlation between the wear behavior of a heavy commercial vehicle (HcV) brake liner tested under controlled laboratory conditions and that in actual field conditions is investigated.A brake liner study for friction and wear is performed on an inertia brake dynamometer (IBD) at different temperatures (200 ℃,250 ℃,and 300 ℃) using 6000 brake actuations in a *** total wear loss of the brake liner at three different temperatures for 6000 brake actuations in IBD is found to be 1.12 *** actual field test is conducted on four different HcVs,namely,a city bus (cB),a high speed bus (HSB),a highway truck (HWT),and a tipper lorry (TL).These HcVs run at different terrain/traffic conditions and load *** comparing the predicted life of the brake liner through the IBD test with the actual life of the brake liner in different HcVs,a vast difference is *** to the large variation of liner life observed between the actual and predicted tests,an extensive field test is *** the field test,the liner with identical formulation is fitted in the four types of *** predicted life of the liner using IBD is then correlated with the field test observation and a correlation factor is *** on this correlation factor,the predicted life of the liner and the achieved life on the HcV are found to be fairly *** study will be useful to design the friction material formulation and to predict the actual life of the brake liner for various HcVs.

关键词： heavy commercial vehicle wear brake liner correlation factor inertia brake dynamometer friction

Physical,Mechanical,and Tribological Attributes of Stir-cast AZ91/Sic_p composite

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Acta Metallurgica Sinica(English Letters) 2014年第2期27卷 295-305页

作者： K.K.Ajith Kumar Abhilash Viswanath T.P.D.rajan U.T.S.Pillai B.c.Pai Material Science and Technology Division CSIR-National Institute for Interdisciplinary Science and Technology

In the present investigation, composites with silicon carbide particle （Sicp） as reinforcement and AZ91 magnesium alloy as matrix have been synthesized using liquid metal stir-casting technique with optimized processing conditions. The composites with good particle distribution in the matrix, and better grain refinement and good interfacial bonding between the matrix and reinforcement have been obtained. The effect of Sicp content on the physical, mechanical, and tribological properties of Mg-based metal matrix composite （MMc） is studied with respect to particle distribution, grain refinement, and particle/matrix interfacial reactions. The electrical conductivity, coefficient of thermal expansion, microas well as macro-hardness, tensile and compressive properties, and the fracture behavior of the composites along with dry sliding wear of the composites have been evaluated and compared with the base alloy.

关键词： composite AZ91D alloy casting alloy Mechanical properties Wear

Limited impacts of occasional tillage on dry aggregate size distribution and soil carbon and nitrogen fractions in semi-arid drylands

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International Soil and Water conservation Research 2024年第1期12卷 96-106页

作者： Wooiklee S.Paye Vesh R.Thapa rajan Ghimire New Mexico State University Agricultural Science CenterClovisNM88101USA New Mexico State University Department of Plant and Environmental SciencesLas CrucesNM88003USA

Tillage management that minimizes the frequency and intensity of soil disturbance can increase soil carbon(c)and nitrogen(N)sequestration and improve the resilience of dryland cropping systems,yet the impact of occasional disturbance on soil aggregate formation and the soil organic carbon(SOc)storage within aggregates has not been studied *** evaluated the effect of four tillage management practices on soil dry aggregate size distribution,aggregate-protected c and N,mineral-associated organic matter carbon(MAOM-c),particulate organic matter carbon(POM-c),and corn(Zea mays L.)and sorghum(Sorghum bicolor(L.)Moench)yields in a semi-arid dryland cropping *** included conventional tillage(cT),strip-tillage(ST),no-tillage(NT),and occasional tillage(OT)management in a corn-sorghum *** macro-aggregates were 51-54%greater under ST,NT,and OT,while small and micro-aggregates were greater in *** tillage reduced soil aggregate-associated c by 28-31%in macro-aggregates and 47-53%in small aggregates at 26 months(M)sampling compared to ST,NT,and *** clay+silt fraction,cT had 14-16%,21-26%,and 36-43%less SOc at 7,14,and 26M samplings,respectively,than ST,NT,and *** associated N was generally similar under ST,NT,and OT,which was greater on average than *** MOAM-c and POM-c under ST,NT,and OT were generally greater than respective SOc fractions under cT at 19 and 26 M after OT *** and sorghum yields were similar among tillage systems in 2020,but greater under ST,NT,and OT than cT in *** results suggest that while frequent intensive tillage can lower SOc and N storage,a single stubble mulch occasional tillage after several years of NT does not lead to soil c and N losses and soil structural instability in semi-arid drylands.

关键词： conventional tillage Occasional tillage Aggregate associated carbon Mineral associated organic matter carbon(MAOM-c) Particulate organic matter carbon(POM-c)

Free radical scavenging potential and HPTLc analysis of Indigofera tinctoria linn(Fabaceae)

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Journal of Pharmaceutical Analysis 2016年第2期6卷 125-131页

作者： Sakthivel Srinivasan Wankupar Wankhar Sheeladevi Rathinasamy Ravindran rajan Department of Physiology Dr.ALM PG Institute of Basic Medical Sciences University of Madras

The objective of this study was to evaluate the free radical scavenging potential and high performance thin layer chromatography （HPTLc） fingerprinting of Indigofem tinctoria （I. tinctoria）, Phytochemical analysis was carried out using standard methods, and free radical scavenging activity of the plant was determined using 2,2-diphenyl-l-picrylhydrazy （DPPH）, nitric oxide （NO） and superoxide anion （O2-） radical scavenging capacities. HPTLc plate was kept in cAMAG TLc Scanner 3 and the Rf values at fin- gerprint data were recorded by WlNcATS software, Aqueous extract of I. tinctoria reliably showed the total phenolics （267.2 ± 2.42 mg/g）, flavonoids （75.43 ± 3.36 mg/g） and antioxidants （349.11 ±8.04 mg/g）. The extract was found to have DPPH （52.08%）, NO （23.12%） and 02 （26.79%） scavenging activities at the concentration of 250 pg/mL and the results were statistically significant compared with ascorbic acid standard （p 〈 0.05）. HPTLc results confirmed that the extract contained several potential active com- ponents such as phenols, flavonoids, saponins and terpenoids as the slides revealed multi-colored bands of varying intensities. This study confirmed that the plant had multipotential antioxidant and free ra- dicals scavenging activities.

关键词： Medicinal plants Indigofera tinctoria Antioxidants HPTLc

Self-lubricating bidirectional carbon fiber reinforced smart aluminum composites by squeeze infiltration process

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Journal of Materials Science & Technology 2019年第11期35卷 2559-2569页

作者： K.M.Sree Manu L.Ajay Raag T.P.D.rajan B.c.Pai Vijay Petley Shweta Namdeo Verma cSIR-National Institute for Interdisciplinary Science and Technology TrivandrumIndia Gas Turbine Research Establishment(GTRE) BangaloreIndia

Self-lubrication is one of the smart material properties required for producing components with enhanced wear resistance and low coefficient of ***(BD)satin weave polyacrylonitrile(PAN)based carbon fiber(cf)fabric preform was successfully infiltrated with Al 6061 alloy by squeeze infiltration *** infiltrated composite shows uniform distribution of carbon fibers in the matrix with the elimination of porosities,fiber damage and close control on the formation of deleterious aluminum carbide(Al4c3)***/Al composite exhibits remarkable wear resistance compared to unreinforced alloy due to the formation of self-lubricating tribolayer on the pin surface,which intercepts the contact of matrix metal to counter *** BD carbon fiber enhanced the hardness and compressive strength of the composite by restraining the plastic flow behavior of *** resolution transmission electron microscopy shows the presence of Al2O3 and MgAl2O4 spinel,confirmed by EDS and SAD pattern,at the composite *** composite shows a lower density of 2.16 g/cm^3 which is a major ad vantage for weight reduction compared to the monolithic alloy(2.7 g/cm^3).

关键词： Metal matrix composites Squeeze infiltration Aluminum carbon fiber fabric Tribology Microstructure

Anemia in cirrhosis:An underestimated entity

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World Journal of clinical cases 2022年第3期10卷 777-789页

作者： Manish Manrai Saurabh Dawra rajan Kapoor Sharad Srivastava Anupam Singh Department of Internal Medicine Armed Forces Medical CollegePune 411040India Department of Medicine and Gastroenterology Command HospitalPune 411040India Department of Medicine Command HospitalKolkata 70027India Department of Gastroenterology Post Graduate Institute of Medical Education and ResearchChandigarh 160012India

Anemia in a patient with cirrhosis is a clinically pertinent but often overlooked clinical *** guidelines highlight the algorithmic approach of managing a patient of cirrhosis presenting with acute variceal hemorrhage but day-to-day management in hospital and out-patient raises multiple dilemmas:Whether anemia is a disease complication or a part of the disease spectrum?Should iron,folic acid,and vitamin B complex supplementation and nutritional advice,suffice in those who can perform tasks of daily living but have persistently low *** does one investigate and manage anemia due to multifactorial etiologies in the same patient:Acute or chronic blood loss because of portal hypertension and bone marrow aplasia secondary to hepatitis B or c viremia?To add to the clinician’s woes the prevalence of anemia increases with increasing disease *** thus aim to critically analyze the various pathophysiological mechanisms complicating anemia in a patient with cirrhosis with an emphasis on the diagnostic flowchart in such patients and proposed management protocols thereafter.

关键词： Anemia cirrhosis Iron deficiency anemia Macrocytic anemia Normocytic anemia

Direct Pointwise comparison of FE Predictions to StereoDIc Measurements:Developments and Validation Using Double Edge-Notched Tensile Specimen

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computer Modeling in Engineering & Sciences 2024年第8期140卷 1263-1298页

作者： Troy Myers Michael A.Sutton Hubert Schreier Alistair Tofts Sreehari rajan Kattil Department of Mechanical Engineering University of South CarolinaColumbiaSC29208USA correlated Solutions Incorporated 121 Dutchman BlvdColumbiaSC29063USA

To compare finite element analysis(FEA)predictions and stereovision digital image correlation(StereoDIc)strain measurements at the same spatial positions throughout a region of interest,a field comparison procedure is *** procedure includes(a)conversion of the finite element data into a triangular mesh,(b)selection of a common coordinate system,(c)determination of the rigid body transformation to place both measurements and FEA data in the same system and(d)interpolation of the FEA nodal information to the same spatial locations as the StereoDIc measurements using barycentric *** an aluminum Al-6061 double edge notched tensile specimen,FEA results are obtained using both the von Mises isotropic yield criterion and Hill’s quadratic anisotropic yield criterion,with the unknown Hill model parameters determined using full-field specimen strain measurements for the nominally plane stress *** Hill’s quadratic anisotropic yield criterion,the point-by-point comparison of experimentally based full-field strains and stresses to finite element predictions are shown to be in excellent agreement,confirming the effectiveness of the field comparison process.

关键词： StereoDIc spatial co-registration data transformation finite element simulations point-wise comparison of measurements and FEA predictions double edge notch specimen model validation