answers on magnetism.docx
- 1. 1. WhichElementsgive MagneticProperties? Ans. The Elementswhichgive MagneticPropertiesOtherthanIronare: 1. Cobalt 2. Nickel 3. Gandolisum 4. Samarium 5. Neodymium 6. Dysposium 7. Erbium 8. Holmium substance Curie temperature(degCentigrade) 1. Iron(fe) 770 2. Cobalt(Co) 1130 3. Nickel(Ni) 358 4. Gandolium 19 5. Dysprosium -185.15 The elmentsthatbestgive magneticpropertiesare Cobalt,Iron,Nickel fromBETH-SLATER MODEL : The factor’s that mainlycontribute towardsMagnetismare: 1. Net-ElectronSpinatthe AtomicLevel 2. Crystal Structure
- 2. Applications : 1. Cobalt(Soft&Hard Magnets,HardDisks,WindTurbines,MRIMachines,Motors,Actuators, Sensors) 2.Samarium-Cobalt(Turbo-Machinery,HighandElectricMotors) 2. HOW TO MAKE ELECTRICAL STEELS FROM PURE IRON OR STEEL ? Ans. 1. Melt the Pure Iron or Scrap Structural Steel,Remove all the elementsIncluding Carbon(Decarbonising) 2. Add AlloyingElement(Siliconinthe requisite Amount) tothe HotMelt 3. PourHot Melt into the Ingotsand Allow itto Solidify toformSlabs 4. Roll the Electrical Steel SlabsintoSheets 5. Pickle the Steel Sheets inAcidssoas to remove the Impurities(any) 6. Anneal andColdRoll the Electrical Steel 7. TensionLeveling–PLAIN STRAIN CONDITIONS –The Sheetsare Pulledand Stretched for perfectflatness. 8. Stamping,LaserorPlasmaCutting – Sheetsare cut intorequiredshapes. Electrical Steel: Electrical Steel is the special kind of steel used in magnetic cores for transformers, generators, and motors. Electrical steel has less carbon content and high silica content. By increasing silic increase resistivity and reduce the potential for eddy currents. Eddy currents in the magnetic field cause loss of energy through heat. Electrical Steel is typically made of recycled steel in an electric arc furnace. HO 3. WhichMicro-Structure givesbestMagneticProperties? Ans.1. the microstructural characteristicsandthe magneticpropertiesof non-orientedelectrical steel gradesduringtheirproductionprocess,The electronmicrographsrevealedthatthe grains in the hot rolledand annealedspecimens,aswell as the elongatedgrains and shear bands in the coldrolledspecimens,all increasedin size as the siliconcontentincreased. 2. Usingthe EBSD technique,the existence ofsub-grainsandsub-grainboundariesin the hot rolledsampleswas observed,indicatingthe occurrence of dynamicrecoveryinsteadof dynamic recrystallizationinthese sites.The sub-grainsalsocoarsenedas the siliconcontentincreased. 3. the highercoercivityandlowerinductioninall of the coldrolledspecimenscanbe attributedto the numerous,fine grains in theirmicrostructure and to theirresidual stresses.The lower
- 3. coercivityandhigherinductionof the annealedspecimenscanbe attributedto theircoarser grain size,the minimizationof residualstressesandthe possibledevelopmentof magnetically favorable texture duringthe final annealing. Ref:Developmentof the microtexture andmagneticpropertiesinnon-oriented electrical steels Ι. Skordilis1*,S.Deligiannis1,A.Alexandratou1,N.I.Makris1,A.Kaldellis1,M.Pissas2,P. Tsakiridis1,G.Fourlaris1 1. How to developmagneticpropertiesof pure iron? Ans.We findthatthe grains ORIENTalong<100> directionshashighmagneticproperties.By preferablyorientingthe grains(Texturing)alongthe <100> ratherthan <110>,<111> magneticpropertiescanbe increased.