Biomedical Engineering. Ceramic Materials. Dr-Ing. Ewald Pfaff. Materials and Processing. Laboratory visit

Transcription

1 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

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

3 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): ZrO 2 Example ZrO V1-6

4 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 r/r 0 [-] V1-8

5 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 , ,50 Ni 2+ 0,69 0,52 O 2- (Anion) 1,32 V1-9 Stable and unstable Ion Configuration unstable stable unstable V1-10

6 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

7 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

8 Functional Cavities Ceramic Membranes Filters V1-15 Ceramic Bearings in MRT Non magnetic properties V1-16

9 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 σ t High-temp. steel σ t Cast iron < < Aluminum alloys Plastics , Structural ral < ceramics Porcelain Glass < V1-18

10 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 (0,03 0,1) 10-4 Plastics , ,2 4,6 Structural ,9 1, ceramic Porcelain > ,5 ε r [ - ] Glass > 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 []* K -1 W/mK J/gK Hightemperature 800 > 6 > 30 > 10-5 steel Cast iron (0,5 1,7) 10-4 Open porosity Shrinkage Electr. conductive Al 2 O 3 (99%) 3, , , ,90 ZrO 2 (MgO) 5, , ,1 10,7 2,5 0,40 ZrO 2 (Y ) 5, , ,5 10,9 2,5 0,40 Al 2 TiO 5 3, , ,5 1,4 0,70 yes CORDIERIT 2, ,0 3 0,73 yes SiSiC 3, , , , ,70 no SSiC 3, , ,8 4, ,60 HPSiC 3, , ,5 5,0 110 HlPSiC 3, , ,5 5,0 110 B 4 C 2, , ,5 5,0 50 0,95 RBSN 2, , , ,0 10 yes no SSN 3, , ,0 3,2 30 HPSN 3, , , HIPSN 3, , ,0-43,5 73 3,2 3, ,70 BN 210 2, , ,78 AIN 3, ,25 5, ,80 at high temp. yes *: A in units for v [m/s] und K l [M Pa m]; v = A K n l **: RT K ***: bulk density: open and closed porosity included V1-20

11 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

12 Stress-Strain-Curves MNm -2 ootnote 2) otnote 1) Stress (fo Stress (foo Bending Tensile S Fibre reinforced Ceramic (Fest Load Capacity) 2 Monolithic Ceramic 2 Steel Polypropylene py 1 0,1 % 0, Strain V1-23 Development of new Ceramic blades for cataract surgery (Eyes) Movie of an operation at a Berlin hospital AVT GmbH Bleichstraße Mülheim an der Ruhr V1-24