Materials Science Notes PDF

· CLASSIFY THE MATERIALS Families-based on atumicimolecular structure metals polymers elastomers ceramics glasses hybrids Properties ofMetals 1 Metallic solids are made up of atoms that share a "cloud" of valence e...

· CLASSIFY THE MATERIALS Families-based on atumicimolecular structure metals polymers elastomers ceramics glasses hybrids Properties ofMetals 1 Metallic solids are made up of atoms that share a "cloud" of valence e (metallic bonding & results in good thermal and electrical conductivity · high elastic stiffness Pure metals are quite soft and ductile (bendable) usually high fracture toughness almost all are crystalline (non-crystalline amorphous metals : + metallic glass) can be shaped joined and surface treated In dif ways ,. can be strengthened by : alloying (mixed metals) - - strain hardening (cold working > heat treating - Dure metals are seldom found in nature 3 In the form of metal usually oxides Metal from Oxide Inacting heat and / or MxOy + S > XM + COy - - electricity metal ore Coke EX : Fe from FezOz Fez8z + 28 + 0 < 2Fe + 2002 seven tonnes of raw material is needed to produce 1 ton of iron 2 tonnes Iron oxide , 1 for coke , 0. 5 ton limestone , 3. 5 tonnes gases Properties of Plastics organic solids with covalent C-c bonds cormentar · joined together by weak hydrogen bonds reak or van de Waal forces + electricity ? Poor conductors of heat i light weight/density Low stiffness (oxless than metals) Not very strong but good strength to weight ratio Low melting temperature 6 Easy to bend and surface treat at a low cost , join , Properties of Elastomers 3 Polymers I vert small ot long chains somed by · gives ability to undergo high elastic deformation wout breaking or deforming Low Stiffness (500 - 5000X less than metals) Properties of ceramics · compounds consisting of at least one non-metal constituent ⑧ i non-metallic inorganic solides made up of 2 or more elements -- & , - g · 2 H held together by covalent or lonic bonds 1 low thermal and electrical conductivity 6 high stiffness very brittle 7 crystalline watah ,  8 high strength i high melting pointss. high strength & elevated temp. difficult to make Join , shape or surface treat , Il very expensive $$ Properties of Glass an ? Mostly non Crystalline Inorganic solids · - % ↑ Often transparent i held bonds together by covalent or conic low thermal and electrical conductivity lower strength stfress melting temperature , ~ , ? i brittle * ↳ ⑳a lower melting point o less $ - Properties of Hybrids (Composite) MINA'S IDEA 1 Combination of 2 or more materials Glass fibre reinforced Polymers (GFRPs) and Carbon Fibre Reinforced Polymers(CFRPS). Almost all materials 2 found in nature are hybrds ex : wood , bone 3 often expensive to make expensive : carbon-fibre composites , Inexpensive : concrete and plywood Al 606/ ↑ - density , mechanical electrical thermal , , , optical , Materials & corrosion properties UNIVERSE FAMILY CLASS SUBCLASS MEMBER ATTRIBUTES Compression Casting ~ Rotation - Injection Molding oining - Transfer material , shape , size range, tolerance roughness , Deformation =jFinishing , a Injection Size minimum batch cost model Processes Molding - , Composta Fram - Extrusionosting Thermoforming Blow molding Gas welding Brace he section thickness material , joint geometry , size range , , Adhesives ↑ relative cost... Welding Gas - & Joining-Fasteners e-beam not gas Processes shaping not bar... /Polish Paint Anodising Finishing -Electroplate I - purpose of treatment coating thickness, surface cust material anodise , Print , powder coat hardness relative cost... Texture... , metallise because material families are based on structure and structure determines properties... , FAMILY MEMBERS HAVE SIMILAR PROPERTIES ENGINEETING DESIGN properties of eng materials judged by. a design's performance objectives : mass , cost environmental , impact constraints : Strength stiffness , , conductivity Minimizing cost cost :$ required manufacture to + deliver price : consumer pays value : Worth to customer Minimizing Environmental Impact global warming pollution control , Q: Recyclable ? Energy needed to produce ? CO2 footprint ? Identifying Materials Life u In Everyday M # Stovetop Kettle' M handle-not metal so no burn iY ↳ d$ body sport , , lid-metal , ↓$ , contains not water , on store. : & -) maintains shope melting Minimizing Mass · reduce volume M V Pc density lower density = X · Minimizing Price for finished Factors volume , short-term supply , future : , geo-political, cost material abundance/scarcity , of raw material, importance Availability of Materials. Local Global vs supply local gives governments + cartels opportunities of influence : Resource Base materials in short supply cannot sustain exponential growth : in demand (* in price) , renewable has a stable outlook Extraction of Raw Materials Environmental Endof life & Refining Labour Impact Finished Product X I processing Energy - > Manufacturing ↑ Political Influence Transportation Measures of Environmental Impact Recyclable (landfill) , energy required ? 20 Production ? (Climate changes ? ATOMIC STRUCTURE AND INTERATOMIC BONDING electrons : much smaller-lighter than nucleus, (-1 , fightly bound inner elections , loose valence electrons nucleus made up of : protons-mutions , bond btw D"and no is stronger than e + nucleus protons equal but opposite charge of et, #of pt : #of e (neutral) , Eisatomiz # = , neutrons heavier thampt , no charge, only stable when round to nucleus N neutron # : , : Atomic Bonds - 1 Metallic Bonding -metalliz elements have electro positive atoms that donate valence e to form sea around atoms net charge = 0 - - () on core held together by Mutual attraction to e- - pure metals are good electrical conductors e move in valence applied voltage > current flow - = -bonds are non directional resulting in good ductility -metals have & points melting 2 Covalent Bonding -sharing valence e bonds from specific angles - covalent bonds are very strong (hard materials ↳4 melting points - limited ductility bot they tend to be directional low electrical conductivity - 3 Ionic Bonding - donation of valence e , filling/emptying the outer shell ↳ have a charge, act as lons cation :+ anson : - 4 Van der Waals Bonds - atoms are neutral - induced or permanent dipole moment - due to electrostatic attraction to polarized molecules secondary bonds Bonding Energy and Internatomic Spacing & · positive nucleus negative nucleus · nucles of ad as electrons · equilibrium distance btw atoms is cause by repulsive/attractive forces ↳ when total interatomic of pair of atoms is at a minimum energy so when net force is to repel/attract No acting Binding minimum Energy required to break or create the bond · energy CRYSTAL STRUCTURE OF METAL a Sen. crystallic patually crysta solid StackingAtomsto Make a 1 crystalline · atoms are perfectly spaced at uniform distance · long range atomic order ORDERED almost all metals and all ceramics 2 Non- crystalline or amorphous # · atoms not uniformly spaced are - ~ nolong range atomic order DISORDERED most glasses and most polymers lattice : collection of (lattice) points repeated 3.D , a arrangement of atoms/1ohs/ molecules in a metal or crystalline solid unit cell smallest part of : a crystal lattice simple repeating unit ,. lattice = repetition of unitcells in dif. direction · there are 14 ways to arrange points In 3.D , grouped into 7 crystal Structures : cubic, tetragonal , or thorhombic, trigonal , hexagonal , , triclinic mondclinic ↳ simple cubic face- centred cubic body - Centred cubic · ⑨ ⑧ · ·- a O ① · ---- 1 atom · ⑧ 4 atom & & ① zatom Atoms per Unit Cell · each lattice point represents an atom · each unit cell has a specific of lattle points - some atoms are shared w other unit cells ↳ corners are shared by 8 cells > face ↳ are shared by cells ↳ within body cell belongs to Coordination Number number of nearest neighboring atoms for particular atom · indicates fight and efficient packing together thursday September 21st gene one 630 - 830 10 questions 49 M C.. Short answer SUMMARY FOR QUIZ 1 Physical Properties : Mechanical thermal , chemical , , electromagnetic Metals Polymers thermal conductivity good C-C monomers make up · · electroconductivity is good joined by H-bonds/van der Waal · · · ↑ elastic stiffness + fractive toughness · thermoplastics have only H-bonds · crystalline(mainly) or amorphous · thermosetting plastic have only covalent extracting metal from oxide is $ 4) cross ·. linkage -> Strength - > reduction rx. · ↓ thermo + electro. Conductivity. · alloys are stronger i better · ↓ elastic stiffness + fracture toughness mechanical properties · amorphors and crystalline Glasses ceramics · non-metalliz , Inorganic solids i covalent · non-metallic , Morganiz solids in covalent · amorphous · ↓ thermo - electro Conductivity · ↓ thermo. - Electro conductivity · a fracture ↑ elastic stiffness but toughness · ↓ elastic stiffness + fracture toughness · crystalline Elastomers Hybrids · polymers in less molecules · 2 or more materials , most in nature joined by covalent bonds · $$ large elastic deformation + shape affects properties the way of combination · · design objectives : mass , cost , environmental impact design constraints Strength stiffness , conductivity :... , Metallic Bonding covalent Bonding · metallic atoms donate valence etoformsed Share et · · net charge = o a melting point · : strong · more with applied voltage => current flow · directional bonds (d specific angles) = bad ductility a d electrical conductivity melting point · · directional bonds good ductility · = non Van Der Waal Bonding Ioni Bonding · neutral atoms · donate e' emptying/filling outer stell , · Dermanentor induced dipde moment due to · con ! cation it anion , :- electrostatic attraction btw polarized molecules equilibrium distance : caused by repulsive + attractive forces Crystalline 1 attice collection of lattice points 3 P arrangementof atoms :.... , · atoms at uniform distance unit cell : part of lattice multiple in dif ,. directions = lattice longrange atomic order · Cubic simple, face centred body. Centred : , Amorphous · corners are shared by 8 cells · not uniformly spaced · face are shared by 2 cells long range within body belongs to cell · no order · Coordination number nearest neighbouring atoms indicates fight and eficient packing of atoms : , Crystal for Metals-BCC body Centred cubic is Non close packed atomic stacking · · closed. Pack direction through the cell where atoms are touching runs diagonally in BCC # atoms/unitcell = 8(5) +1 = 2 atoms/unitcell Dimensions -- d: lateral length ofun it cell L: radius of atom · dBx = 4/5 R L=2+a =a = Ea 1 = 4R = 53 @ Density of iron at room temperature - BC) structure e room temp Rie = 0. 124 nm = 0. 124x10-9 m Afe = 56 g/mo density-mass = (Not m) (mass of me atom) = 2 atoms (weight # volume avogadros a3 (4/31)3 -g/mol 2 atoms X 90g/cm3 = 16 023x1023 aroms/mol). = 1. (4/5(0. 124x10 - 9)73 Atom ene i Packing Factor of BCC V atoms = 2(4/3TR3) 8/zTR3 = APF Volume of atoms in cell 34/53R3 = volume of cell V cell = [YGRY = = 3) 68 % of BCC is atoms 32 % is = 0. 68 means , nothing closed packed Atomic stacking ABABAB Sequence in layers of atoms => Hexagonal Close Packed (HCP). ABCABLAB2 Sequence in layers of atums => Face. Centred Cubic (FCC) FCC direction diagonally across theface is #atoms/unit cell 8 (5) 6(E) 4 atoms/unit cell = + = Ertaa] Dimensions um Ac = 2 Atomic packing Factor - vol atoms in unit cell. = (13) = E R3 APF = LBTR3 3(1652) R3 vol Unit cell. = a = (2R)" = 16ER3 = 0. 74 CDH - 6 atoms 12 atoms onthe corners on " volume inside APF ↑ 3 atoms in 100/ volume inside = 0. 74 2 atoms on the face in 2 of volume inside average APF of amorpous materials 15 0. 24 E Iron BCC to FC2 when heated above 912 C changes from BCC state the density :. % In , IS PB2Ife = 1. 87 gicm3. Whatis the densityin the FCC state ? Rie = 0 124 hm. mass of 1 FCC unit cell - volume of - unit cell Are = 55 85. glmo [atomkell) (MofFe) = a = (2( vre)3 p = m/v Avogadro's constant = (252 (0. 124x10 - 9))3 455 85) 31 x10- 2am3 =. = 4. 6. 023x1023 = 3 71. x10-22 g/unit cell P = 8 61 g/cm3 Mi. 2 61x103 8 glms/900cm/m> =. Density of Dure crystalline metal n : atems in one unit cell #atoms/unit cell (mass of an atum) density : A : M, gimol volume ofunit cell Vc volume of unit cell (cm3) : Na arogadros constant (6 023x1023atoms(moll A :. CRYSTAL STRUCTURE OF CERAMICS · - ·Mo O X de Structure - - anions are oxygen larger than metal cations (size effect) - close packed oxygen in lattice (usually + (c) - cations fit into interstitial sites among oxygen lons Factors that Determine Crystal Structure 1 Relative Con size ~ formation of stable structures maximize # of oppositely charged on neighbours 2 Maintenance of charge reflected In chemical formula Neutrally ~ netchange should be o , AX-type Structures · either FCC or BCC · same # of A atoms as X atoms different sizes though · smaller atom sits in interstitial locations , larger atoms its in regular atomic sites ex : Sodium chloride(rock sait), zinc blende, cesium chloride NaCl > - ci(larger) , Nat (smaller) Ins > - s(largers , In (smallers CS21 > - BCC , 2S + (larger) , 21 (smallers n' (An [Ax) + n' # of formula : units (molecules) p = & An : Sum of atomic weights Of all A atoms VN 2 Ax : Sum of atomic weights of all X atoms V : volume N: Avogadro's constant Density of salt [Awn = 22 99. g/mol v = a3 = [2(VNa + + c, )) 0 = 4(22. 99 + 35. 45) (1 813 x 10 28)(6 023x1023) 181x10-9]3 - 2Aci 35 45 glma (2(0 102x10. = = -". 0.. +. V Nat = 0 102 nm 813x10- 28m3 2 14 106 g/me. = = 1. x 181. 0 nm rc -. n' = 4 = 2 14. g/km3 Coordination Number and Ionic Radil rcation coordination shape on - Predicting for E number Vanion 20 155 2 linear Coordination # 6. 0. 5502- 0. 155-0 225. 3 triangular = 0 225 0. -. 414 4 tetrahedral 0 414. - 0 732. 6 octahedral 0 732-1 8.. g Cubic AXz ~ Huorite ~ cations in cubic site ~ anti fluorite structure position of cations + anions - reversed ABX3 - Perovskite Structure ~ complex oxide (BaTIOg) Glass Materials Quartz-crystalline strong but buttle , , a melting temp. Window glass-non-crystalline weak but brittle& temp. d , room , melting temp , ductive & high temp. POLYMERS · If C = C bondis broken the molecule becomes, a free radical saturated hydrocarbons : a each bonded 4 to other atoms sition · double + triple bonds are somewhat unstable - common hydrocarbon monomers : alcohols, ethers acids, aldehydes aromatic hydrocarbons , , isomerism - - 2 compounds with same chemical formula Microstructure we linear , branched , cross-linked, network & increasing strength mers-random P , alternating , blocked , grafted ex : synthetic rubbers Molecular weight of polymer degree of polymerization = Molecular weight of one repeat unit - Crystalline Polymers · folds back on itself easily · small side groups · no branching degree of Crystallinity : depends on processing conditions + chain configuration cooling rate during crystallization : upon cooling through melting point, polymers become highly viscous. requires sufficient time for random + entangled chains to become ordered in viscous liquid properties n · linear Polymers-crystallization is more easily accomplished be/chain alignment is not prevented · not favored for polymers that have chemically complex monomer structures linear polyvinyl chloride is more likely - · alternating so Polymer are more likely than random boy chains can algn easier MATERIALS AND ENERGY · most processes require a certain amount of work to be done · Heat often provides most of the energy required to do that work Att Heat ~ energy required for a phase change - associated in change in entropy Heat-vibration of Able a toms - at absolute zero (ok/-273c) , atoms cease to oscillate - average vibrational energy of each atom is equal to 3 KBT KB : Bolton's constant relate , av. Kinetic energy to thermodynamic temp. 1. 38x18-23 2 atom /. How is thermal energy stored in materials ? - - think about solids' atoms connected by a spring atomic vibration stretches one and compresses the other Ad max = energy max Ad = 0 = energy min - heat is the motion of atoms - insolids, motion is limited by bonds is neighbouring atoms - vibrations form standing waves i various wavelengths each atom has 3 distinct wavelengths (specific heat) mincapacity ~ amount of energy ↑ temp required to of a given mass Cp = /g. K for gases , commonly at constant volume, Cr & denotes a measurement at constant pressure av amplitude of each vibration results in energy RBT - - If volume is 1 , then the energyper Unit is 3KBT/e by atomic volumes don't called VOLUMETRIC HEAT CAPACITY vary much, 3) Cp = 3RB EX: Estimate the energy required to raise one cubic meter of aluminum from 20 to 660. Au = C PAT energy/volume= AUXP = (2600/Rg 1) (600 2017 = (1 7 x 100 >/kg) x(2710k9/m3) -.. = 1 7 x. 106 > /19 = 4. 6 X10")/m3 mmmperature varying properties properties vary with temp many material. - SUMMARY FOR QUIZ 2 Crystal Structure of Metal BCC - non-close packed atomic stacking Vatom = 2 (4/34R3) - close. packed direction diagonally through cell - 2 atoms/unit cell Vcell = (4/3R)3 - dimensions : a Bcc 4/3 R = FCC - close packed direction diagonally across face Vatom = 4(4/3πR3) - 4 atom/cell - dimensions : aFc = ZER V cell = (2ER)3 ABCAB2 Sequence - density of pure crystalline metal HCP-6 atoms/cell # atoms in cell) (atomic weight ~ 12 in corners in 16 volume inside & = (volume of cell) (Avogadro's #) ~ 3 in 100% volume inside ~ 2 on face in 12 volume inside - ABABAB Sequence average APF of amorphous materials : 0 64. Crystal Structure ofCeramic Oxide-oxygen anions are larger than metal cations AX - FC2 or BCC - close. packed oxygen in lattice (FCC) - same # of A and X atoms dif sizes , - cations fit into interstitial space around anions - small atom interstitial spaces in , large in regular atomic sites Factors formation of Stable structure - # of Helgborring cons AXc-fivorite net charge should be zero sites of anions/cations reversed - - #of Molecules) (atomic weights of Adtoms + A W of X atoms). ABX2. p = - Perovskite structure (volumes (Avogadro's constant) complex oxide - 6) ass quartz-crystalline strong but brittle, , & melting temp atn! coordination. shape window-amorphous , weak but brittle & room temp. , d melting temp., number ductile & high temp. 20 155. 2 linear 0 155-0 225 3 triangular Polymers.. 4 tetrahedral 0 225 0 414 becomes free radical network - If C C bond is broken , M.. · = 0 414 0 732 6 octahedral hydrocarbons in rustable double triple bonds - - +.. t cross-linked 0 732-1 8 g Cubic (molecular weight.. warn · polymerization = (M W one.. repeat unit) branched u - Crystalline folds on itself : , side groups, no branching linear linear polymers easy crystalline formation ~ ~ alternating polymers less likely u complex structures rare Materials and Energy 231 1 38x10 - latent heat is energy required for phase change Centropy. - atom K - a. , - sensible heat is vibration In atoms , at OK atoms cease to oscillate av. = 3kBT - vibrations btw atoms form various wavelengths 3ki pCp = = -volume of atom CONDUCTING HEAT Thermal Expansion - ↓ ) - units : (k x = - most materials expand when heated - thermal strain caused by a change in temp is characterized by Linear Coefficientof Thermal Expansion EX : A bar has a length of 100 0 mm when measured. at 20 2.. If the material has a thermal expansio Coefficient of 10. 2x10-6/ , what's the expected change in length of the bar at 293 C ?. 10 2x10-3k = + dL. * 100mm (293 + 273)k 120+273)k - al = 0 27846mm. - the amplitude of atomic vibrations increase with heat the "springs" btw atoms are not linear - Stiffer In compression than in tension - ↑ temp. = vibrate about an increasing mean spacing stronger Steeper force Spacing curve + deeper energy well less expansion - bonds => = lower coefficient, a Young's modulus ↑ temp , melting. 10-3 for E = E In GPa X = for Think conductivity mal ~ rate at which heatis conducted through a solid under Steady state conditions - x(T Tu) Fornier's Law X - q= Wim -. = q heat flux per unit : : area , X Heat is transmitted through solids 3 in ways : 1 The motion of Free Electrons (metals) 2 Radiation (transparent materials 3 Thermal Vibrations (all materials) ~ phonons ~ elastic waves that travel at the speed of sound speed of sound in a solid : Co ~ heat is not conducted at the same speed due to phonons scattered lattice imperfectly in mean free path : Im , average distance btw scattering events , approx. 0 01 mm. - net flux of photons across a distance : a = PCpColm dX in Former's Law : x= p2pcolm  for transient conditions (temp changing) heatflor is governed by Thermal Diffusivity - - , a = =my pCp = pp = measured by subjecting one end of a material to a heat pulse and measuring the time it takes the other end to sense the heat Thermal Property Charts Manipulating ~ Thermal Properties Thermal Expansion : depends on bond strength + stiffness , hard to manipulate CTE Heat Capacity : essentially constant for all materials , reducing density is only approach Mnermal depends on heat capacity /constant), Conductivity : speed of sound(You d stiffness density) , and mean free path (lattice defects) ~ same lattice defects that impede dislocation motion ( = ) ↑ yield strength) also scatters phonons and free electrons ( =C ↓ thermal conductivity) MECHANICAL PROPERTIES OF MATERIALS applied force Stress : o = area supporting force = Pa 1 MPa 104 Pa = 1 GPa = 1000 Pa amount object stretches Strain : = ~ dimensionless, expressed as percent length of object mmmmal Stress + Strain ~ when applied force acting normal to the are a - can detensile or compressive O = F/A E= (L-20)/Lo Jensile elastic strain from : fully recoverable strain resulting an applied stress 8 : E3 E = Young's modulus  Stress-strain wapplied force is parallel to the area ~ stress :I = Fs/A Strain : Y W/Lo = T = 6) Shear Madrlos rostatic Stress Dilation ~ + ~uniform pressure Initial volume , Vo applied in all directions to a body of volume Strai (dilation) : - = (V-Vol/o P = /A Bulk modulus Modes of Loading - i uniaxial tension unlaxial compression tension compression and shear/from , bending) shear (from torsion) Diaxial tension (from internal pressure Poisson's Ratio , y - - when stretched elastically in # , the material will contract in transverse direction maintains volume 2 E transverse V: Ey L Ex WWo = = = most = " - Ey Eaxial Wo EX: Determine the lateral (transverse) strain in an aluminum specimen (E = 15 GPa , v= 0 3). subjected to an axal tensile stress of Fompa. Ex = - vXEy 50 = - 0. 3 X-