Biomedical Engineering Material a Science ce Ceramic Materials Dr-Ing. Ewald Pfaff Lesson 1: Lesson 2: Lesson 3: Fundamentals Materials and Processing Exercise Hip Joint Laboratory visit Questions Preparation for Examination: 22. July 2011 (Proposal) V1-1 Material Groups Metals Broeckmann Ceramics Pfaff Polymeres Michaeli Composites Broeckmann, Michaeli, Pfaff V1-2
Complementary Sciences from Powder to Component 3 Si + 2 N 2 2 Si 3 N 4 Atoms Molecules Powder Microstructure Sample Component nm m mm m 100 mg Chemistry, Physics 100 g Material Science 1 kg Engineering Science V1-3 Materials Metals (metallic) Ductile (> 5 slide systems) Chemically reactive Conductive (therm. und electric) Dense sphere packing (density) 0,3 mm A B C Glas (ionic i / covalent) Direction independed properties Optical transparency Isolator Ceramics (ionic / covalent) Breaking elongation 1, strain Chemical resistant, temperature resistant, hard amorph = near regularity without distant regularity polycrystalline = near regularity and distant regularity Polymeres (covalent; Dipole-Dipole strengths, van-der-waals) Elastic and plastic deformable Chemical resistant Isolating (electr. and therm.) Temperature depending properties (brittle at T, decomposition at T ) 0 X Z 0 Si 0 0 Y V1-4
Types of Bonding Metal Bonding Undirected, not dedicated Very high coordination numbers Dense sphere packing i.e. iron, messing Ionic Bonding Undirected, dedicated High coordination numbers Sphere packing i.e. Al 2 O 3, ZrO 2 Covalent Bonding Directed and dedicated - Density - E-Modulus - Melting point - Corrosion resistance - Thermal expansion i.e. SiC, Si 3 N 4 Bonding electron belongs to to one atom a lot of atoms to two atoms V1-5 Ionic (heteropolar) Bonding Atom 1 emits one or more electrons and becomes electropositiv Atom 2 absorbs one or more electrons and becomes electronegativ Coulomb attraction bonds Ions Quelle (ZrO2): http://www.tf.uni-kiel.de/matwis/amat/mw1_ge/kap_3/exercise/s3_3_4.html ZrO 2 Example ZrO V1-6
Covalent Bonding Electrons are shared between 2 atoms similar Electronegativity Source: library.thinkquest.org/05aug/o1o87/bond.html Example: SiC Source: TU Freiberg, Institut für Werkstoffwissenschaften V1-7 Bond Strengths in Comparison ] 0 15 N/mol F [1 1,4 1,2 1 0,8 0,6 0,4 0,2 0 0,0608 1,2337 0,622 0,1852 covalent ionic metallic Van-der-Waals 0 1 2 3 r/r 0 [-] V1-8
Ion Radius Ion Radius [Å] r cat /r an Al 3+ 0,51 0,39 Si 4+ 0,42 0,32 Zr 4+ 0,79 0,59 Ti 4+ 0,68 0,52 Mg 2+ 066 0,66 050 0,50 Ni 2+ 0,69 0,52 O 2- (Anion) 1,32 V1-9 Stable and unstable Ion Configuration unstable stable unstable V1-10
Stability Areas of Coordination Polyeder in Ion Crystals 0,414 coordination number r cat /r an 6 Octa- hedron Al 3+ Fe 3+ Mn 3+ Li 3+ TiO 6 AlO 6 MgO 6 0,732 Zr 4+ 8 Cubes Na 1+ CaO 8 ZrO 8 1,00 V1-11 Definition Ceramic Ceramic are all non metal anorganic materials or: Ceramic Materials are compositions of metal or semi metal elements with non metal elements V1-12
Definition Ceramic Cearamis are: Wear resistant Bio compatible Pump components Corosion resistant HIP joint balls hard Membranes Cutting tools V1-13 Definition Ceramic Ceramics are: dense or porous TiATi SiC 50µm TiATi 200µm SiC 20µm 200µm V1-14
Functional Cavities Ceramic Membranes Filters V1-15 Ceramic Bearings in MRT Non magnetic properties V1-16
Composites, schematic Fibre compound Particle compound Penetration compound C-fibres in SiC for car breaks Layer compound ZrO 2 in Al 2 O 3 Si in SiC Ceramic-Metal in multilayer capacitors Glass with polymer films in bullet-proof glass V1-17 Material Density ρ [g/cm 3 ] Bending Strength σ h [MPa] Material data in comparison (1) Tensile Strength σ z [MPa] Critical stress intensity factor K Ic [MPa m 1/2 ] Impact toughness - [J/m 2 ] Ultimate strain [%] Youngmodulus Hardness GPa - [HV] Steel 78 7.8 - σ t 360 140 10 5 10 6 10 20 200 200 400 700 High-temp. steel 7.8 - σ t 500 1000 Cast iron 7.3 300 600 150 400 50 154 200 < 900 15 25 10 4 < 2 70-130 150 250 Aluminum 2.8 150-300 350 45 10 5 5 20 70 30 140 alloys Plastics 0.9 2.2 10 150 10 705 0,3 4 10 4 2 1200 10 Structural ral 225 2.25 30 28 2.8 10.5 10 6 10 8 <01 0.1 30 450 1200 ceramics 5.98 1200 3200 Porcelain 2.4 50 70 50 100 1 2.5 Glass 2.2 2.5 70 70 100 < 1 10 2.5 200 800 V1-18
Material data in comparison (2) thermal electric Material Max. working cte Heat Spec. Electr. Relative temperature conductivity Resistivity Permittivity T max [ C] α(rt-1000 C) [10-6 K -1 ] λ [W/mK] ξ [Ωcm] Steel 400 >10 >30 >10-5 Aluminum alloys 250 20-26 70-130 (0,03 0,1) 10-4 Plastics 200 20-180 0,14-025 10 15-10 18 2,2 4,6 Structural 1000-2000 1 10,9 1,4-155 10-2 -10 14 8-10 ceramic Porcelain 1000 2 6 1-6 > 10 13 5 6,5 ε r [ - ] Glass 200-1200 3-10 1-2 >10 13 3-19 V1-19 Material data of ceramics Material Properties (short- and longtime reliability ) * * * E b4 m 0V K IC log A n * * c p g/cm 3 GPa - MPa - MPa MPa m []* - 10-6 K -1 W/mK J/gK Hightemperature 800 > 6 > 30 > 10-5 steel Cast iron 400 5-18 13-60 (0,5 1,7) 10-4 Open porosity Shrinkage Electr. conductive Al 2 O 3 (99%) 3,99 410 0,25 330 10 456 4,9-40 60 8 30 0,90 ZrO 2 (MgO) 5,65 210 0,30 520 25 572 8,1 10,7 2,5 0,40 ZrO 2 (Y 2 0 3 ) 5,90 210 0,30 950 20 1082 10,5 10,9 2,5 0,40 Al 2 TiO 5 3,10 30 0,22 30 20 34 1,5 1,4 0,70 yes CORDIERIT 2,10 80 105 10 145 2,0 3 0,73 yes SiSiC 3,06 360 0,19 330 13 416 4,0-95 160 4,5 140 0,70 no SSiC 3,10 400 0,17 430 10 595 4,8 4,7 100 0,60 HPSiC 3,18 440 0,16 610 12 789 5,5 5,0 110 HlPSiC 3,20 440 0,16 610 12 789 5,5 5,0 110 B 4 C 2,51 450 0,18 400 3,5 5,0 50 0,95 RBSN 2,40 150 0,20 220 15 267 2,8-43 80 3,0 10 yes no SSN 3,25 290 0,26 600 15 727 6,0 3,2 30 HPSN 3,30 300 0,26 660 20 752 7,0-95 130 HIPSN 3,30 300 0,26 800 20 911 7,0-43,5 73 3,2 3,2 35 35 0,70 BN 210 2,10 75 80 40 4,0 50 078 0,78 AIN 3,25 350 335 3,25 5,7 155 0,80 at high temp. yes *: A in units for v [m/s] und K l [M Pa m]; v = A K n l **: RT - 1275K ***: bulk density: open and closed porosity included V1-20
c, B 20 to 40 (10 to 20) Basic Equations (1) 1 1 t, B B (1) σ t,b tensil stress at breakage σ c,b B compressive stress at breakage shear stress Stress-Strain-Curve σ t tensile stress t t EE Fracture Mechanics K IC t (2) strain E E E-modulus A J R sharp t c A, R J (3) a Y 2 a σ t,c K IC a Y σ A σ R σ J critical tensil stress critical stress intensity factor length of crack dimansional factor application stress residual stress joining stress V1-21 Basic Equations (2) Size Effect F const t1 ( ) B t2 V V Z 2 Z1 1 mv ln lnv (5) σ t1, σ t2 V Z1,V Z2 peak stresses of two distributions volumes Subcritical Crack Growth da v AK I dt n ln v a length of crack t time n K I stress intensity n1 factor (6) A K A1 IC critical stress intensity factor K I K IC ln K I V1-22
Stress-Strain-Curves MNm -2 ootnote 2) otnote 1) Stress (fo Stress (foo Bending Tensile S 600 500 400 300 200 Fibre reinforced Ceramic (Fest Load Capacity) 2 Monolithic Ceramic 2 Steel 1 100 Polypropylene py 1 0,1 % 0,2 5 10 15 20 200 400 600 Strain V1-23 Development of new Ceramic blades for cataract surgery (Eyes) Movie of an operation at a Berlin hospital AVT GmbH Bleichstraße 12 45468 Mülheim an der Ruhr V1-24