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Influence of bimodal grain size distribution on the corrosion behavior of friction stir processed biodegradable AZ31 magnesium alloy

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Journal of Magnesium and Alloys 2016年第1期4卷 68-76页

作者： N.Saikrishna g.pradeep kumar reddy Balakrishnan Munirathinam B.Ratna Sunil Department of Mechanical Engineering Rajiv Gandhi University of Knowledge Technologies(AP-IIIT)Nuzvid 521202India Department of Mechanical Engineering Vignana Bharathi Institute of TechnologyHyderabad 501301India Department of Metallurgical and Materials Engineering Indian Institute of Technology MadrasChennai 600036India

In the present study,AZ31 magnesium alloy sheets were processed by friction stir processing(FSP)to investigate the effect of the grain refinement and grain size distribution on the corrosion *** refinement from a starting size of 16.4±6.8µm to 3.2±1.2µm was attained after ***,bimodal grain size distribution was observed in the nugget zone with a combination of coarse(11.62±8.4µm)and fine grains(3.2±1.2µm).Due to the grain refinement,a slight improvement in the hardness was found in the nugget zone of FSPed *** bimodal grain size distribution in the stir zone showed pronounced influence on the corrosion rate of FSPed AZ31 as observed from the immersion and electrochemical *** the X-ray diffraction analysis,more amount of Mg(OH)_(2) was observed on FSPed AZ31 compared with the unprocessed *** measurements demonstrated the higher corrosion current density for FSPed AZ31(8.92×10^(−5)A/cm^(2))compared with the unprocessed condition(2.90×10^(−5)A/cm^(2))that can be attributed to the texture effect and large variations in the grain size which led to non-uniform galvanic intensities.

关键词： AZ31 Mg alloy Biodegradable implants grain size distribution Corrosion Friction stir processing,texture

An investigation on the hardness and corrosion behavior of MWCNT/Mg composites and grain refined Mg

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Journal of Magnesium and Alloys 2018年第1期6卷 83-89页

作者： N.Saikrishna g.pradeep kumar reddy Balakrishnan Munirathinam Ravikumar Dumpala M.Jagannatham B.Ratna Sunil Department of Mechanical Engineering Rajiv Gandhi University of Knowledge Technologies(AP-IIIT)Nuzvid 520201India Department of Mechanical Engineering Vignana Bharathi Institute of TechnologyHyderabad 501301India Department of Metallurgical and Materials Engineering Indian Institute of Technology MadrasChennai 600036India Department of Mechanical Engineering Visvesvaraya National Institute of Technology(VNIT)Nagpur 440010India Reactor Engineering Division Bhabha Atomic Research CentreMumbai-400085India Department of Materials Science and Engineering Department Delft University of TechnologyDelftNetherlands

In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical *** observations showed that the thickness of the produced composite layer was in the range of 2500μ*** resulted uniform distribution of CNT near the surface while agglomerated layers in the *** refinement of Mg achieved by FSP improved the hardness but significant enhancement in the hardness value was observed for FSPed MWCNT/Mg *** polarization studies revealed that the increase in corrosion current density was observed for MWCNT/Mg composite compared with grain refined Mg and pure Mg,implying the significance of secondary phase(MWCNT)in decreasing the corrosion resistance of the composite.

关键词： Friction stir processing MWCNT/Mg composite Hardness Basal texture Corrosion resistance

Effect of aluminum content on machining characteristics of AZ31 and AZ91 magnesium alloys during drilling

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Journal of Magnesium and Alloys 2016年第1期4卷 15-21页

作者： B.Ratna Sunil K.V.ganesh P.Pavan g.Vadapalli Ch Swarnalatha P.Swapna P.Bindukumar g.pradeep kumar reddy Department of Mechanical Engineering Rajiv Gandhi University of Knowledge Technologies(AP-IIIT)Nuzvid 521202India Department of Mechanical Engineering Vignana Bharathi Institute of TechnologyHyderabad 501301India

Magnesium(Mg)and its alloys are now becoming the promising choice for various structural applications due to their low density and high specific strength compared with other light metals such as aluminum and its *** all Mg alloys,AZ(aluminum and zinc)series is the most widely used alloy system for various structural ***,machining of magnesium and its alloys involves certain issues due to their brittle nature and risk of inflammability unlike other nonferrous ***,alloys with considerable amount of secondary phase may exhibit different machining characteristics during metal cutting *** the present study,two AZ series alloys AZ31 and AZ91 were selected and drilling operation was performed to assess the effect of the secondary phase amount and distribution on machining *** operation was carried out at different sets of process parameters and cutting forces were obtained and the chips which have been produced during drilling were *** the results,it can be clearly understood that the presence of secondary phase(Mg_(17)Al_(12))has a significant influence on cutting *** in cutting speed has reduced the required cutting force and load fluctuations in all the cases.

关键词： Light metals Magnesium Drilling AZ series Cutting force Compounds

Joining of AZ91 Mg alloy and Al6063 alloy sheets by friction stir welding

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Journal of Magnesium and Alloys 2018年第1期6卷 71-76页

作者： B.Lakshmana Prasad g.Neelaiah M.gopi Krishna S.V.V.Ramana K.Sai Prakash g.Sarika g.pradeep kumar reddy Ravikumar Dumpala B.Ratna Sunil Department of Mechanical Engineering Rajiv Gandhi University of Knowledge Technologies(AP-IIIT)Nuzvid 520201India Department of Mechanical Engineering Vignana Bharathi Institute of TechnologyHyderabad 501301India Department of Mechanical Engineering Visvesvaraya National Institute of TechnologyNagpur 440010India

In the present work,the effect of process parameters on joining of AZ91 Mg alloy and Al6063 aluminum alloy sheets during friction stir welding(FSP)was studied.A successful joint was achieved at 1100 *** rotational speed and 25 mm/min tool travel *** of tool rotational speed and tool travel speed has observed a profound effect on the material flow mechanisms at the nugget *** the microstructural studies,the joint formation was observed as mainly due to mechanical mixing of the *** level of metallurgical continuity at the nugget zone was observed as poor and a sharp interface at the joint was *** microhardness measurements across the weld joint also revealed the lack of establishment of a perfect metallurgical bonding.X-ray diffraction analysis of weld zone showed presence of both magnesium and *** from the preliminary observations,it can be understood that the joining of AZ91 Mg alloy and Al6063 alloy can be achieved by FSP;however,complex issues in material mixing still need further investigations.

关键词： Friction stir welding Dissimilar joints Magnesium Aluminum Nugget zone

Joining of AZ31 and AZ91 Mg alloys by friction stir welding

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Journal of Magnesium and Alloys 2015年第4期3卷 330-334页

作者： B.Ratna Sunil g.pradeep kumar reddy A.S.N.Mounika P.Navya Sree P.Rama Pinneswari I.Ambica R.Ajay Babu P.Amarnadh Department of Mechanical Engineering Rajiv Gandhi University of Knowledge Technologies(AP-IIIT)Nuzvid 521202India Department of Mechanical Engineering Vignana Bharathi Institute of TechnologyHyderabad 501301India

Two dissimilar magnesium(Mg)alloy sheets,one with low aluminium(AZ31)and another with high aluminium(AZ91)content,were successfully joined by friction stir welding(FSW).The effect of process parameters on the formation of hot cracks was investigated.A sound metallurgical joint was obtained at optimized process parameters(1400 rpm with 25 mm/min feed)which contained fine grains and distributed β(Mg_(17)Al_(12))phase within the nugget *** increasing trend in the hardness measurements has also confirmed more amount of dissolution of aluminium within the nugget zone.A sharp interface between nugget zone and thermo mechanical affected zone(TMAZ)was clearly noticed at the AZ31 Mg alloy side(advancing)but not on the AZ91 Mg alloy side(retreating).From the results it can be concluded that FSW can be effectively used to join dissimilar metals,particularly difficult to process metals such as Mg alloys,and hot cracking can be completely eliminated by choosing appropriate process parameters to achieve sound joint.

关键词： Dissimilar metal joining Magnesium alloys Friction stir welding AZ31 AZ91

Unlocking new potential of clinical diagnosis with artificial intelligence:Finding new patterns of clinical and lab data

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World Journal of Diabetes 2024年第3期15卷 308-310页

作者： pradeep kumar Dabla Department of Biochemistry Govind Ballabh Pant Institute of Postgraduate Medical Education and ResearchDelhi 110002India

Recent advancements in science and technology,coupled with the proliferation of data,have also urged laboratory medicine to integrate with the era of artificial intelligence(AI)and machine learning(ML).In the current practices of evidencebased medicine,the laboratory tests analysing disease patterns through the association rule mining(ARM)have emerged as a modern tool for the risk assessment and the disease stratification,with the potential to reduce cardiovascular disease(CVD)*** are the well recognised leading global cause of mortality with the higher fatality rates in the Indian population due to associated factors like hypertension,diabetes,and lifestyle ***-driven algorithms have offered deep insights in this field while addressing various challenges such as healthcare systems grappling with the physician *** medicine,well driven by the big data necessitates the integration of ML techniques and high-quality electronic health records to direct the meaningful *** technological advancements enhance the computational analyses for both research and clinical *** plays a pivotal role by uncovering meaningful relationships within databases,aiding in patient survival prediction and risk factor *** potential in laboratory medicine is vast and it must be cautiously integrated while considering potential ethical,legal,and privacy ***,an AI ethics framework is essential to guide its responsible *** AI algorithms with existing lab practices,promoting education among healthcare professionals,and fostering careful integration into clinical settings are imperative for harnessing the benefits of this transformative technology.

关键词： Laboratory medicine Artificial intelligence Machine learning Association rule mining Cardiovascular diseases

A comprehensive review on pharmacognosy, phytochemistry and pharmacological activities of 8 potent Prunus species of southeast Asia

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Journal of Traditional Chinese Medicine 2024年第3期44卷 620-628页

作者： Shikha Agrawal Adarsh kumar Ankit kumar Singh Harshwardhan Singh Suresh Thareja pradeep kumar Department of Pharmaceutical Sciences and Natural Products Central University of PunjabBathinda 151401India

genus Prunus comprising around 430 species is a vast important genus of family Rosaceae, subfamily amygdalaoidae. Among all 430 species, around 19 important species are commonly found in Indian subcontinent due to their broad nutritional and economic importance. Some most common species of genus Prunus are Prunus amygdalus, Prunus persica, Prunus armeniaca, Prunus avium, Prunus cerasus, Prunus cerasoides, Prunus domestica, Prunus mahaleb, etc. A newly introduced species of Prunus i.e Prunus sunhangii is recently discovered which is morphologically very similar to Prunus cerasoides. Plants of Prunus species are short to medium-sized deciduous trees mainly found in the northern hemisphere. In India and its subcontinent,it extends from the Himalayas to Sikkim, Meghalaya,Bhutan, Myanmar etc. Different Prunus species have been extensively studied for their morphological,microscopic, pharmacological and phytoconstituents characteristics. Total phenolic content of Prunus species explains the presence of phenols in high quantity and pharmacological activity due to phenols. Phytochemical screening of species of genus Prunus shows the presence of wide phytoconstituents which contributes in their pharmacological significance and reveals the therapeutic potential and traditional medicinal significance of this genus. genus Prunus showed a potent antioxidant activity analyzed by 1,1-diphenyl-2-picryl-hydrazyl radical assay. Plant species belonging to the genus Prunus is widely used traditionally for the treatment of various disorders. Some specific Prunus species possess potent anticancer, anti-inflammatory,hypoglycemic etc. activity which makes the genus more interesting for further research and findings. This review is an attempt to summarize the comprehensive study of Prunus species from its distribution, morphological characters to phytoconstituents, and pharmacological activity.

关键词： Rosaceae Prunus antineoplastic agents hypoglycemic agents distribution phytochemistry review

Aerodynamics of a Tandem-Bladed Axial Compressor Rotor under Circumferential Distortion at Different Rotational Speeds

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Journal of Thermal Science 2024年第4期33卷 1340-1356页

作者： Amit kumar Jerry T.JOHN A.M.pradeep R.A.DAKKERMANS Dragan KOZULOVIC Department of Aerospace Engineering Indian Institute of Technology BombayMumbai400076India Department of Automotive and Aeronautical Engineering Hamburg University of Applied Sciences20099HamburgGermany Institute of Jet Propulsion Bundeswehr University Munich85577NeubibergGermany

For most aircraft engines,inflow distortion is *** distortion is known to degrade the aerodynamic performance and stable operating limits of a *** rotor configuration is an arrangement that effectively controls the growth of the boundary layer over the suction surface of the ***,a higher total pressure rise can be achieved through this unconventional design approach involving the splitting of the blade into forward and aft *** is expected that the effect of inlet flow distortion would be more severe for a tandem-rotor design due to the greater flow turning inherent in such ***,this aspect needs to be thoroughly *** present study discusses the effect of circumferential distortion on the tandem-rotor at different rotational ***-annulus RANS simulations using ANSYS CFX are used in the present *** performance of the rotor at a particular flow coefficient and different rotational speeds is *** total pressure and efficiency are observed to drop at lower mass flow rates under the influence of circumferential *** loss region in each blade passage is mainly associated with the blade wake,tip leakage vortex,secondary flow,and boundary ***,their contribution varies from passage to passage,particularly in the distorted *** the lower span,the wake width is found to be higher than that at a higher *** to the redistribution of the mass flow,the circumferential extent reduces at a higher *** the undistorted sector,the strength of the tip leakage vortex is significantly higher at the design rotational speed than at lower *** distortion near the tip region promotes an early vortex breakdown even at the design operating *** adversely affects the total pressure,efficiency,and stall *** clean flow conditions,this phenomenon is only observed near the stall *** the design operating condition,the breakdown of the forward rotor tip l

关键词： tandem rotor circumferential distortion loss tip leakage vortex vortex breakdown diffusion factor aerodynamics of compressor blade

Identification of optimal composition with superior electrochemical properties along the zero Mn^(3+)line in Na_(0.75)(Mn-Al-Ni)O_(2)pseudo ternary system

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Journal of Energy Chemistry 2024年第9期96卷 206-216页

作者： Hari Narayanan Vasavan Manish Badole Samriddhi Saxena Velaga Srihari Asish kumar Das Pratiksha gami Neha Dagar Sonia Deswal pradeep kumar Himanshu kumar Poswal Sunil kumar Department of Metallurgical Engineering and Materials Science Indian Institute of Technology IndoreSimrol 453552India High Pressure&Synchrotron Radiation Physics Division Bhabha Atomic Research Centre400085 MumbaiIndia School of Physical Sciences Indian Institute of Technology MandiHimachal Pradesh 175005India Center for Electric Vehicle and Intelligent Transport Systems Indian Institute of Technology IndoreSimrol 453552India

Biphasic layered oxide cathodes,known for their superior electrochemical performance,are prime candidates for commercializing in Na-ion ***,we unveil a series of P3/P2 monophasic and biphasic Al-substituted Na_(3/4)Mn_(5-x/8)Al_(2x/8)Ni_(3-x/8)O_(2)layered oxide cathodes that lie along the‘zero Mn^(3+)line’in the Na_(3/4)(Mn-Al-Ni)O_(2)pseudo-ternary *** structural analysis showed a larger Na^(+)conduction bottleneck area in both P3 and P2 structures with a higher Al3+content,which enhanced their rate *** each composition,the P3/P2 biphasic compound with nearly equal fractions of P3 and P2 phases outperformed their monophasic counterparts in almost all electrochemical performance *** synchrotron XRD measurements obtained for the monophasic P3 and biphasic P2/P3 samples revealed the absence of the O3 phase during *** high structure stability and faster Na^(+)transport kinetics in the biphasic samples underpins the enhancement of electrochemical properties in the Al-substituted P3/P2 *** results highlight fixed oxidation state lines as a novel tool to identify and design layered oxide cathodes for Na-ion batteries in pseudo-ternary diagrams involving Jahn-Teller active cations.

关键词： Layered oxides Biphasic cathode Operando Synchrotron XRD Electrochemical behavior Cyclic performance