ceramic applications in the automotive industry

E

S

KIT – University of the State of Baden-Württemberg andNational Large-scale Research Center of the Helmholtz Association www.kit.edu

Institute for Applied Materials - Ceramics in Mechanical Engineering

Michael. J. Hoffmann

Ceramic Applications in the Automotive Industry

Institute for Applied Materials- Ceramics in Mechanical Engineering1

filter, catalyst carrierfuel injectors high pressure pump

electronic device

PTC heater

knocking sensor

Functional Ceramicsspark and glow plugs, oxygen sensor,

knocking sensor, parking distance control, PTC heaters, fuel injection systems

Ceramics components in automotive applicationsCeramics components in automotive applications


filter, catalyst carrierfuel injectors high pressure pump

electronic device

PTC heater

knocking sensorStructural Ceramics

pump components (sealings), brake discs, catalyst support, particulate filter,

Ceramics components in automotive applicationsCeramics components in automotive applications


Projection of Total Energy Demand and Energy MixProjection of Total Energy Demand and Energy Mix

• Liquid fuels will still significantly contributeto up-coming energy demands

• Combustion engines are necessaryin the next decades

• Individual transport: long range distance,trucks, hybrids


2010 2015 2020 2025 203060

70

80

90

100

110

120

130

140

150

CO

2 Em

issi

on [g

/km

]

Year

37,3 mpg

42 mpg

57,4 mpg

78,4 mpg

European Fuel-Economy Goal up to 2025European Fuel-Economy Goal up to 2025

US Goal: 100 g/km

Goal can only be obtained by more efficient combustion engines→ Downsizing concept (smaller, but more efficient engines)


Downsizing conceptDownsizing concept

Downsizing is based on the principle of a reductionin engine size in order to reduce consumptionwithout 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 CO2 emissions between 5% for diesel models and40% for gasoline models by 2020. These engines should be able to remaindominant for a long time in the car market.


Downsizing conceptDownsizing concept

Downsizing is already reality in the present US market


• 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

OutlineOutline


Piezo technology increases efficiency and reduces emission→ already used in Diesel systems, but with a high potential for gasoline systems

Piezoelectric Driven Common Rail Fuel Injection TechnologyPiezoelectric Driven Common Rail Fuel Injection Technology

fuel injectorhigh pressure pump

electronic device

courtesy: Robert Bosch GmbH



High fuel injection pressure is needed to reduce droplet size (-40%), → decrease of fuel consumption and pollutant emissions (-80%)

-40 %

ceramic partsmetal parts

Pfister et al. Cer. Trans. (2011)


Fuel evaporation in combustion chamberFuel evaporation in combustion chamber

source: Spicher, KIT-IFKM


3-Piston High Pressure Pump for Gasoline Engines3-Piston High Pressure Pump for Gasoline Engines

Cam/sliding-shoe contact is tribological highly loaded due to an insufficient lubricationof petrol with increasing pressure → ceramic components can be a solution

KIT / IFKM, Pfister, Spicher


SSiC / SSiC SiAlON / SiAlON

Friction coefficient in the cam/sliding-shoe contactFriction coefficient in the cam/sliding-shoe contact

Silicon carbide and SiAlONs indicate a similar behaviour with a verylow friction coefficients at a system pressure of 50 MPa



The texture significantly improves the performance of self-mated silicon carbide at low speed or low contact force

-75 %

Effect of surface texturing of the cam/sliding-shoe contactEffect of surface texturing of the cam/sliding-shoe contact




• Spark plugs






OutlineOutline


Gasoline direct injection systemGasoline direct injection system

An ignitable mixture for low and high loads is only formed in a very narrow spatial zone

Source: KIT / IFKM, Spicher


Future trends for spark plugs in fuel-efficient enginesFuture trends for spark plugs 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


Manufacturer

Strength distribution and typical failure mechanismsof commerical spark plugs

Strength distribution and typical failure mechanismsof commerical spark plugs

compaction defects

Strength distribution reflects also the electric breakthrough behaviour→ Most current commercial materials do not match the requirements


Challenges:• smaller diameter → higher thermal and mechanical loading→ strength must be increased by enhanced processing conditions• adjustable resistance• high voltage → increase in electrical breakthrough

Future trends for spark plugs in fuel-efficient enginesFuture trends for spark plugs in fuel-efficient engines



• Spark plugs






OutlineOutline


Metal Matrix Composites for Highly Loaded Engine PartsMetal Matrix Composites 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 bya local reinforcement with ceramics (preform concept).

after German, 1994


local reinforcement(cermic preform)

Local reinforcement of pressure die-casted Al-MMCsLocal reinforcement of pressure die-casted Al-MMCs


250 µm

Ceramic foams

Porosity: 85-95%cell size depends on polymer foam

Preparation of Porous Ceramic PreformsPreparation of Porous Ceramic Preforms

Pore filler concept

Porosity: up to 75%Pore size and shapedepend on filler

40 µm

Freeze casting

Porosity: 20-85%Ice crystals form final pores

100 µm

Different types of ceramic preforms can be manufactured byusing powder technology processes.

Mattern et al., JECS (2004).


ceramic wall

Ice lamella

Cooled plate

Preparation of freeze-casted Al-MMCsPreparation of freeze-casted Al-MMCs

Waschkies et al., JACS (2009)2 mm

S. Roy & A. Wanner, Compos. Sci. Technol. (2008)

100 µm


0,01 0 ,1 1 101E -13

1E -12

1E -11

1E -10

1E -9

perm

eabi

lity

str

engt

h [m

2 M

Pa]

e ffective m elt velocity [m /s]

.

.

Failure region

squeezecasting

pressurecasting

Freeze casted preforms can be used for pressure casting,while preforms with pore fillers and bottle neck pores will break

Estimation of failure probability for different perform typesEstimation of failure probability for different perform types

Survival region

freeze casting

foams

with pore fillers

Mattern et al., JECS (2004).



• Spark plugs






OutlineOutline


dhkl dhkl E-Feld

Piezoelectric effect (intrinsic)

E-Feld

∆L

Domain switchung (extrinsic)

→ High strain materials rely on both intrinsic and extrinsic effect

Mechanisms of high field strain in ferroelectric ceramicsMechanisms of high field strain in ferroelectric ceramics

E

S

Strain behaviour


+

-80 Volt

80 µm

0,16 µm strain at 20 kV/cm

Typical strain of a donor-doped Pb(Zr,Ti)O3 ceramic (PZT): 0.15 - 0.2 % at 20-30 kV/cm→ Multilayer device

+

-

1 cm

20.000 Volt

20 µm strain at 20 kV/cm

Strain behaviour of a ferroelectric ceramic at 20 kV/cmStrain behaviour of a ferroelectric ceramic at 20 kV/cm

0,0 0,5 1,0 1,5 2,0 2,50,00

0,04

0,08

0,12

0,16

0,20 P Z T

Hig

h fie

ld s

train

[%]

Electric field [kV/mm]



electronic

internal electrodes (AgPd)

PZT-layers

termination→ typical driving voltage: 100 V, total strain 20-30 µm

courtesy: Robert Bosch GmbH


Requirements for piezoelectric actuators for fuel injection systemsRequirements for piezoelectric actuators for fuel 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)

• “low cost“

• challenge: replacement of PZT by lead free ferroelectrics


RB KNN‐PSU reference samples

0

100

200

300

400

500

600

0 50 100 150Temperature, °C

d33*, pm/V

LFL493 ( ‐ ref)ML172 ( ‐ 61 mu)ML503 ( ‐ 144 mu)

20 kV/cm

d 33*

(pm

/V)

0

100

200

300

400

500

600

d 3

3* (p

m/V

)0 50 100 150

0

200

400

600

800

1000

La-PZT 53/47 53.5/46.5

Temperature (°C)

0 50 100 150

Temperature (°C)

(Li,Sb)-doped KNN

33%

160%

Comparison of Pb(Zr,Ti)O3 and a lead-free ceramicComparison of Pb(Zr,Ti)O3 and a lead-free ceramic

Lead-free ceramics show a lower strain for a similar electric field strengthand exhibit a much stronger temperature dependence of strain

E = 2 kV / mm E = 2 kV / mm



• Spark plugs






OutlineOutline


The increasing efficiency of fuel saving cars requires a supplementary heat system basedon functional ceramics showing a positive temperature coefficient resistance (PTCR) effect.

Heat deficiency for car heating systems with efficient enginesHeat deficiency for car heating systems with efficient engines

source: eberspächer catem, Germany


0 50 100 150 200 250 300 350 400103

104

105

106

107

Spe

cific

Res

ista

nce

[Ω/c

m]

Temperature [°C]

TC

• PTC-effect is based on the temperature depended potential barrier at the grain boundary high electrical resistance above TC

• The ferroelectric phase equals the charge of the potential barrier below TClow electrical resistance

PTC effect in donor-doped BaTiO3-based ceamicsPTC effect in donor-doped BaTiO3-based ceamics

0 5 10 15 20 25 30 35

0

50

100

150

200

250 (Bi0,5K0,5)

Zr

Ca

(Bi0,5Na0,5)Pb

Cur

ie T

empe

ratu

re T

C [°

C]

x [mol %]


1 Vaporizer2 Car Heater3 PTC auxiliary heater

Highly efficient cars do not produce enough „waste energy“ for heating

BaTiO3-based PTC heating elementsBaTiO3-based PTC heating elements

source: eberspächer catem, Germany


Seat heater for convertibles

PTC effect in donor-doped BaTiO3-based ceamicsPTC effect in donor-doped BaTiO3-based ceamics

OEMs favour different local heating elements to reduce total energy consumption



• Spark plugs






OutlineOutline

Institute for Applied Materials- Ceramics in Mechanical Engineering3737 RTC | 06/23/2007 | © 2007 Robert Bosch LLC and affiliates. All rights reserved.

StructuralProperties

FunctionalProperties

MultifunctionalProperties

Composites

MultimaterialComposites

PowderTechnology

Complexity of requirement profiles for the system

Com

plex

ity in

mat

eria

ls p

repa

ratio

n ReliabilityQualityCostsWeight…

ThermomechanicalTreatment

Requirements and Challenges for Materials ResearchRequirements and Challenges for Materials Research


+

-

06

Return

Time

Prototype

07 08 09 10 11 12 13 14 15

Reduction ofproduct life cycle

SOP

Requirements and Challenges for Product DevelopmentRequirements and Challenges for Product Development

→ Reduction of product development time due to shorter product life cycles

Reduction of productdevelopment time

Support through modelingand simulation and bettercoordination


Modeling and simulation across the whole length scaleModeling and simulation across the whole length scale

length scale

10-10 - 10-9 m 10-7 - 10-5 m 10-2 - 10-1 m

FE-methods for calculationof coupled loading conditions→ Design optimization

Phase field or vertex dynamicsimulation

→ Microstrutural design

Ab-initio calculationsMD- simulation

→ New materals

courtesy: P.F. Becher


from the first idea to the product

Fixed first idea

Raw projectBoard project

Product in the marketAccepted products

Economically successful products

source: Kienbaum, Bullinger

ConclusionConclusion

ceramic applications in the automotive industry

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