Ceramic Applications in the Automotive Industry

Transcription

1 Ceramic Applications in the Automotive Industry Michael. J. Hoffmann Institute for Applied Materials - Ceramics in Mechanical Engineering S E KIT University of the State of Baden-Württemberg and National Large-scale Research Center of the Helmholtz Association

2 Ceramics components in in automotive applications fuel injectors high pressure pump filter, catalyst carrier electronic device Functional Ceramics spark and knocking glow sensor plugs, oxygen sensor, knocking sensor, parking distance control, PTC heaters, fuel injection systems PTC heater 1

3 Ceramics components in in automotive applications fuel injectors high pressure pump filter, catalyst carrier electronic device Structural Ceramics pump components knocking sensor (sealings), brake discs, catalyst support, particulate filter, PTC heater 2

4 Projection of of Total Energy Demand and Energy Mix Liquid fuels will still significantly contribute to up-coming energy demands Combustion engines are necessary in the next decades Individual transport: long range distance, trucks, hybrids 3

5 European Fuel-Economy Goal up up to to 2025 CO 2 Emission [g/km] ,3 mpg 42 mpg Year 57,4 mpg 78,4 mpg US Goal: 100 g/km Goal can only be obtained by more efficient combustion engines Downsizing concept (smaller, but more efficient engines) 4

6 Downsizing concept Downsizing is based on the principle of a reduction in engine size in order to reduce consumption without affecting power. Measures: - Reduction of number of cylinders - Supercharging (use compressed air) - Direct injection systems Challenges and Needs: - Injection control system - High pressure fuel pump - High thermal and mechanical loading Downsizing can reduce the CO 2 emissions between 5% for diesel models and 40% for gasoline models by These engines should be able to remain dominant for a long time in the car market. 5

7 Downsizing concept Downsizing is already reality in the present US market 6

8 Outline High pressure pump systems for gasoline engines Spark plugs Porous ceramics for local reinforcement of metal matrix composites Piezoelectric injection systems PTC heating elements General conclusions 7

9 Piezoelectric Driven Common Rail Fuel Injection Technology fuel injector high pressure pump electronic device courtesy: Robert Bosch GmbH Piezo technology increases efficiency and reduces emission already used in Diesel systems, but with a high potential for gasoline systems 8

10 Piezoelectric Driven Common Rail Fuel Injection Technology metal parts ceramic parts -40 % High fuel injection pressure is needed to reduce droplet size (-40%), decrease of fuel consumption and pollutant emissions (-80%) Pfister et al. Cer. Trans. (2011) 9

11 Fuel evaporation in in combustion chamber source: Spicher, KIT-IFKM 10

12 3-Piston High Pressure Pump for forgasoline Engines KIT / IFKM, Pfister, Spicher Cam/sliding-shoe contact is tribological highly loaded due to an insufficient lubrication of petrol with increasing pressure ceramic components can be a solution 11

13 Friction coefficient in in the cam/sliding-shoe contact SSiC / SSiC SiAlON / SiAlON Pfister et al. Cer. Trans. (2011) Silicon carbide and SiAlONs indicate a similar behaviour with a very low friction coefficients at a system pressure of 50 MPa 12

14 Effect of of surface texturing of of the cam/sliding-shoe contact -75 % Pfister et al. Cer. Trans. (2011) The texture significantly improves the performance of self-mated silicon carbide at low speed or low contact force 13

15 Outline High pressure pump systems for gasoline engines Spark plugs Porous ceramics for local reinforcement of metal matrix composites Piezoelectric injection systems PTC heating elements General conclusions 14

16 Gasoline direct injection system Source: KIT / IFKM, Spicher An ignitable mixture for low and high loads is only formed in a very narrow spatial zone 15

17 Future trends for forspark plugs in in fuel-efficient engines Microstructure with a glassy phase and pores 4 µm Challenges Distance between electrodes will increase Higher voltage will be applied longer spark Pressure increase in combustion chamber higher thermal and mechanical loading reduction in size 16

18 Strength distribution and typical failure mechanisms of of commerical spark plugs Manufacturer compaction defects Strength distribution reflects also the electric breakthrough behaviour Most current commercial materials do not match the requirements 17

19 Future trends for forspark plugs in in fuel-efficient engines Challenges: smaller diameter higher thermal and mechanical loading strength must be increased by enhanced processing conditions adjustable resistance high voltage increase in electrical breakthrough 18

20 Outline High pressure pump systems for gasoline engines Spark plugs Porous ceramics for local reinforcement of metal matrix composites Piezoelectric injection systems PTC heating elements General conclusions 19

21 Metal Matrix Composites for for Highly Loaded Engine Parts Engine part manufactured by pressure die casting of Al-based alloys Inhomogeneous cooling causes thermal stresses that can be minimized by a local reinforcement with ceramics (preform concept). after German,

22 Local reinforcement of of pressure die-casted Al-MMCs local reinforcement (cermic preform) 21

23 Preparation of of Porous Ceramic Preforms Pore filler concept Freeze casting Ceramic foams 40 µm 100 µm 250 µm Porosity: up to 75% Pore size and shape depend on filler Porosity: 20-85% Ice crystals form final pores Porosity: 85-95% cell size depends on polymer foam Mattern et al., JECS (2004). Different types of ceramic preforms can be manufactured by using powder technology processes. 22

24 Preparation of of freeze-casted Al-MMCs 100 µm ceramic wall Ice lamella Cooled plate Waschkies et al., JACS (2009) 2 mm S. Roy & A. Wanner, Compos. Sci. Technol. (2008) 23

25 Estimation of of failure probability for for different perform types permeability strength [m 2 MPa].. 1E-9 1E-10 1E-11 1E-12 foams freeze casting Survival region with pore fillers Failure region squeeze casting 1E-13 0,01 0, effective melt velocity [m/s] pressure casting Mattern et al., JECS (2004). Freeze casted preforms can be used for pressure casting, while preforms with pore fillers and bottle neck pores will break 24

26 Outline High pressure pump systems for gasoline engines Spark plugs Porous ceramics for local reinforcement of metal matrix composites Piezoelectric injection systems PTC heating elements General conclusions 25

27 Mechanisms of of high field strain in in ferroelectric ceramics Piezoelectric effect (intrinsic) Strain behaviour S dhkl dhkl E-Feld E Domain switchung (extrinsic) L E-Feld High strain materials rely on both intrinsic and extrinsic effect 26

28 Strain behaviour of of a ferroelectric ceramic at at kv/cm High field strain [%] 0,20 P Z T 0,16 0,12 0,08 0,04 0,00 0,0 0,5 1,0 1,5 2,0 2,5 Electric field [kv/mm] Volt µm strain at 20 kv/cm 80 Volt cm 0,16 µm strain at 20 kv/cm 80 µm Typical strain of a donor-doped Pb(Zr,Ti)O 3 ceramic (PZT): % at kv/cm Multilayer device 27

29 Piezoelectric Driven Common Rail Fuel Injection Technology electronic PZT-layers courtesy: Robert Bosch GmbH typical driving voltage: 100 V, total strain µm termination internal electrodes (AgPd) 28

30 Requirements for forpiezoelectric actuators for forfuel injection systems cofiring with internal electrodes (multilayer device) high strain operating temperatures from -40 to 150 C small temperature dependence of strain high reproducibility (mass production) lowcost challenge: replacement of PZT by lead free ferroelectrics 29

31 Comparison of of Pb(Zr,Ti)O 33 and a lead-free ceramic E = 2 kv / mm RB KNN PSU reference samples 20 kv/cm E = 2 kv / mm LFL493 ( ref) ML172 ( 61 mu) ML503 ( 144 mu) d 33 * (pm/v) La-PZT 53/ / Temperature ( C) 33% d 33 * (pm/v) d33*, pm/v % (Li,Sb)-doped KNN Temperature, C Temperature ( C) Lead-free ceramics show a lower strain for a similar electric field strength and exhibit a much stronger temperature dependence of strain 30

32 Outline High pressure pump systems for gasoline engines Spark plugs Porous ceramics for local reinforcement of metal matrix composites Piezoelectric injection systems PTC heating elements General conclusions 31

33 Heat deficiency for forcar heating systems with efficient engines source: eberspächer catem, Germany The increasing efficiency of fuel saving cars requires a supplementary heat system based on functional ceramics showing a positive temperature coefficient resistance (PTCR) effect. 32

34 PTC effect in in donor-doped BaTiO 33 -based ceamics Specific Resistance [Ω/cm] T C Temperature [ C] Curie Temperature T C [ C] 250 (Bi 0,5 K 0,5 ) (Bi 0,5 Na 0,5 ) Pb Ca Zr x [mol %] PTC-effect is based on the temperature depended potential barrier at the grain boundary high electrical resistance above T C The ferroelectric phase equals the charge of the potential barrier below T C low electrical resistance 33

35 BaTiO 33 -based PTC heating elements 1 Vaporizer 2 Car Heater 3 PTC auxiliary heater source: eberspächer catem, Germany Highly efficient cars do not produce enough waste energy for heating 34

36 PTC effect in in donor-doped BaTiO 33 -based ceamics Seat heater for convertibles OEMs favour different local heating elements to reduce total energy consumption 35

37 Outline High pressure pump systems for gasoline engines Spark plugs Porous ceramics for local reinforcement of metal matrix composites Piezoelectric injection systems PTC heating elements General conclusions 36

38 Requirements and Challenges for formaterials Research Complexity of requirement profiles for the system Complexity in materials preparation Composites Structural Properties Multimaterial Composites Functional Properties Reliability Quality Costs Weight Multifunctional Properties Powder Thermomechanical Treatment Technology RTC 06/23/ Robert Bosch LLC and affiliates. All rights reserved.

39 Requirements and Challenges for forproduct Development Return + Prototype SOP Reduction of product development time Support through modeling and simulation and better coordination Time Reduction of product life cycle Reduction of product development time due to shorter product life cycles 38

40 Modeling and simulation across the whole length scale length scale m m m courtesy: P.F. Becher Ab-initio calculations MD- simulation New materals Phase field or vertex dynamic simulation Microstrutural design FE-methods for calculation of coupled loading conditions Design optimization 39

41 Conclusion Fixed first idea from the first idea to the product Raw project Board project Product in the market Accepted products Economically successful products source: Kienbaum, Bullinger 40