RF9 Physics of Failure Sliding contact phenomena Material related failure.
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Transcript of RF9 Physics of Failure Sliding contact phenomena Material related failure.
RF9
Physics of Failure
Sliding contact phenomenaMaterial related failure
RF9 Program Day 2
slide 2RF9 - Physics of Failure2013
9:00-9:15 Introduction
9:15-9:30 Friction related failures
9:30-10:00 Demo load capacity of sliding contacts
10:00-10:15 Break
10:30-11:30 PoF Friction
11:30-11:45 Application of gained results
11:45-12:30 PoF Wear
12:30-13:30 Lunch
13:30-14:00 Demo Dry Sliding and EP additives
14:00-15:00 PoF Material selection
15:00-15:15 Break
15:15-16:15 PoF Lubrication
16:15-16:45 Application of gained results
16:45-17:00 Summary of the day
slide 32013
Adv Eng Design Page 222
Material & Coating Selection
RF9 - Physics of Failure – Material Selection
slide 42013
Adv Eng Design Page 222
Case study Storm surge Barrier
RF9 - Physics of Failure – Material Selection
A movable storm surge barrier is constructed making dikes along the river unnecessary.
slide 52013
Adv Eng Design Page 222
Case study Storm surge Barrier
RF9 - Physics of Failure – Material Selection
F=35.000 Metric Tonnes Loadm=15.000 Metric Tonnes Load
p<150 MPaµ<0.1
Material selection ?
slide 62013
Adv Eng Design Page 222
Material & Coating Selection
RF9 - Physics of Failure – Material Selection
7.1 Materials in relative slidingMetals, polymers, technical ceramics
7.2 Coatings and surface treatmentsSurface treatments and classification
7.3 Material selectionCase study: storm surge barrier
slide 72013
Adv Eng Design Page 249
Material Selection: Metals
PF9 - Physics of Failure – Material Selection
steel, bronze, cast iron…
slide 82013
Adv Eng Design Page 249
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Why metal-metal combinations are always lubricated. Without lubrication:
Metals of relative high hardness:
+ Relative good wear resistance(class 4)
- High friction, scatter(µ=0.3...0.6)
Metals of relative low hardness:+ Relative low friction
(µ=0.08...0.14)- High wear rate
(class 6)
Without lubricationSevere adhesive friction / adhesive wear
slide 9Seminar - Physics of Failure2013
Case 1
slide 102013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
slide 112013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
0
c.max 0
/ ,
f
c
q F v Fv
q A pv A Ld
T T qR
T Tpv
RA
slide 122013
Adv Eng Design Page 209
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
Dependent on heat conduction
µ(p,v)
slide 132013
Adv Eng Design Page 309
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
Polymers• Thermoplastics
two types of thermoplastics- crystalline- amorphous
• Thermosetscannot be reshaped by heatingare stiff and strong in relation to thermoplasticsare often reinforced with glass or carbon fibers
• Elastomersrubbery polymers, can stretch easily and
instantly return to its original shape when released.
slide 142013
Adv Eng Design Page 309
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
Thermoplastics
+ Do not need to be lubricated+ Low weight+ Injection molding
- Low stiffness and strength - Mechanical properties strongly depend on temp - Poor heat conduction, large thermal expansion - Large machining tolerances
slide 152013
Adv Eng Design Page 253
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
slide 162013
Adv Eng Design Page 253
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
Amorphous plastics+ Less mold shrinkage - Susceptible to chemical attack - Lower wear resistance
Crystalline plastics+ Higher strength and rigidity+ Higher wear resistance+ Good chemical resistance to oils and grease
(silicone based oils, water, soap…)
slide 172013
Adv Eng Design Page 257
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
price
slide 182013
Adv Eng Design Page 261
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
slide 192013
Adv Eng Design Page 260
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
Self lubricating plastics are compounded with- PTFE, MoS2, Graphite, Silicone oil, Aramid fibres
Fiber reinforced plastics are reinforced with
- Glass fibers, Carbon fibers Steel counter surface
- HRc>50, Ra=0.3-0.4 μm Aramid fibers
- Improves resistance to abrasion especially against counter surfaces of lower hardness such as aluminum and plastics.
The low friction is a result of a strongly
adhering transfer film on the counter surface
Water lubrication precludes the formation of a
dry lubricant film, resulting in high wear rate
slide 202013
Adv Eng Design Page 258, 261
Material Selection: Polymers
RF9 - Physics of Failure – Material Selection
slide 212013
Adv Eng Design Page 222
Case 2
RF9 - Physics of Failure – Material Selection
Bronze St.50 (1.0050)
Pmax=10…20 MPa
Pmax=5…10 MPa
Failure mode:
slide 222013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of non-metals or a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
slide 232013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of non-metals or a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
slide 242013
Adv Eng Design Page 250
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Difference in hardness of a factor between 3 to 5 Less tendency to adhesion (Pb, Sn) Good embed ability for abrasive particles Leveling out of stress concentrations
slide 252013
Adv Eng Design Page 222
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Main bearing
Marine bearing
slide 262013
Adv Eng Design Page 210
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Elastic supportPorous bearing
Oil circulation within the pores
slide 272013
Adv Eng Design Page 222
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Porous iron
Hardened shaft
slide 282013
Adv Eng Design Page 222
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Porous bronze (PbSn) bearings
μ=0.06-0.10, k=0.3-0.9 10-15 m2/N, PV=1.75 106 Pa·m/s
slide 292013
Adv Eng Design Page 306, 35, 221
Case 3
RF9 - Physics of Failure – Material Selection
slide 302013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of non-metals or a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
Layered molecular structure of graphite
slide 312013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion1) : Combinations of a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength
Stainless steel
Thin oxide layer
Stainless steel bolts require special purpose lubricants
slide 322013
Adv Eng Design Page 306, 35, 221
Case 3
RF9 - Physics of Failure – Material Selection
Successful application in clearance fits to prevent fretting corrosion (left) or galling (right)
Layered molecular structure of graphite
AF-Coating(MoS2, graphite)
slide 332013
Adv Eng Design Page 306
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Successful application in screw joints
Particle orientation after initial sliding
AF-Coating, P>100MPa, µ<0.1
Layered molecular structure of graphite
AF-Coating(MoS2, graphite)
slide 342013
Adv Eng Design Page 309
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
Layered molecular structure of graphite
slide 352013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion1) : Combinations of non-metals or a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength
Galvanized
High corrosion resistance
slide 362013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
Case 4
slide 372013
Adv Eng Design Page 267
Material Selection: Tech. Ceramics
RF9 - Physics of Failure – Material Selection
Al2O3 = AluminaSiC = Silicon CarbideSi3N4 = Silicon NitrideZrO2 = ZirconiaZTA = Zirconia Toughened Alumina
+ High hardness and wear resistance+ Low specific weight+ Excellent high temperature properties+ Resistance to corrosive environment - Low toughness (brittle)
slide 382013
Adv Eng Design Page 151
Material Selection: Tech. Ceramics
RF9 - Physics of Failure – Material Selection
slide 392013
Adv Eng Design Page 151
Material Selection: Tech. Ceramics
RF9 - Physics of Failure – Material Selection
+ High resistance to abrasive wear (elastic deformation)+ High resistance to adhesive wear (small γ/H ratio)
1/3~HHigh surface energy but small ratio of surface energy and hardness
slide 402013
Adv Eng Design Page 266
Material Selection: Tech. Ceramics
RF9 - Physics of Failure – Material Selection
Hydrodynamic bearing operatingin abrasive environment (Pavg= 6 MPa)
slide 412013
Adv Eng Design Page 504, 523
Material Selection: Tech. Ceramics
RF9 - Physics of Failure – Material Selection
Jewel bearings
Industrial jewels
Diamond pivots
slide 422013
Adv Eng Design Page 169
Case 5
RF9 - Physics of Failure – Material Selection
slide 432013
Adv Eng Design Page 169
Material Selection: Metals
RF9 - Physics of Failure – Material Selection
How to reduce friction and wear due to adhesion Combinations of non-metals or a non-metal against a metal Carburizing or nitriding High hardness of both surfaces Difference in hardness of a factor between 3 to 5 High roughness Strong oxide film Lubricant, liquid or solid Thin layer with low shear strength.
Case 5
slide 442013
Adv Eng Design Page 269
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Bonding strength
slide 452013
Adv Eng Design Page 270
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
slide 462013
Adv Eng Design Page 268
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Advantage of dissimilar materials(Metallurgical incompatible materials).
slide 472013
Adv Eng Design Page 273
Material Selection
RF9 - Physics of Failure – Material Selection
Introducing residual compressive stressesup to half the yield strength in order to improve the fatigue strength.
Laser peening imparts a layer of compressive stress that is four times deeper than that attainable from conventional shot peening
slide 482013
Adv Eng Design Page 268
Material Selection: Coatings & surface treatments
PF9 - Physics of Failure – Material Selection
Nickel and chromium plating
slide 492013
Adv Eng Design Page 268
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Laser cladding
Laser cladding is an effective way to refurbish and improve worn or damaged industrial components
slide 502013
Adv Eng Design Page 273
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Substrate low alloyedC-steel, Clad materialStellite 21
Pre-machining: removal of worn and with lubricant diffused material
Post-machining to required dimensions
slide 512013
Adv Eng Design Page 270
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Al2O3 TiO2
WC
HVOF Spraying
slide 522013
Adv Eng Design Page 273
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
CVD -TiN
slide 532013
Adv Eng Design Page 274
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
slide 542013
Adv Eng Design Page 268
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Adhesive wear(Galling)
DLC coatings in sheet metal forming, µ<0.1
slide 552013
Adv Eng Design Page 275, 276
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
slide 562013
Adv Eng Design Page 275, 276
Material Selection: Coatings & surface treatments
RF9 - Physics of Failure – Material Selection
Summary• The wear resistance of a machine part
is determined by the wear resistance of it’s surface.
• This means that for the surface other demands can be made than for the bulk material
• There are plenty of options to improve the surface quality• Treatments in the surface / on the surface
+ hard surface + tough core
Adv Eng Design Page 275, 276
Case study Storm surge BarrierHalf of the Netherlands is below sea level. To prevent flooding dikes along the coast line are raised to delta level.
Raising the dikes along the river are unwanted and would be very expensive. A dam isn’t possible while the seaport of Rotterdam must remain accessible.
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
Adv Eng Design Page 275, 276
slide 682013 RF9 - Physics of Failure – Material Selection
F=35.000 tonnesm=15.000 tonnes
p<150 MPaµ<0.1
Material selection ?
Case study Storm surge Barrier
slide 692013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
The allowable pressure in sliding contacts between metals is limited by seizure
Steel – cast iron 5…10 MPa, μ=0.12…0.18 Steel - CuSn or CuAl alloys 10…20 MPa, μ=0.12…0.18
In screw joints contact pressures up to 100 MPa are common, but the sliding motion is limited to one single move and μ=0.12…0.18 Zinc plated to prevent
corrosion and seizure.
slide 702013
Adv Eng Design Page 306
Solid lubricants
RF9 - Physics of Failure – Material Selection
Successful application in screw joints
Particle orientation after initial sliding
AF-Coating, P>100MPa, µ<0.1
Layered molecular structure of graphite
AF-Coating(MoS2, graphite)
slide 712013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
Adv Eng Design Page 309
Solid lubricants are used for conditions where conventional lubricants are inadequate
Reciprocating motion, fretting Improvement of running in conditions Extreme contact pressures Shock loading High temperatures Ceramics
slide 722013 PF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
Adv Eng Design Page 307
P<150MPa, µ<0.1
slide 732013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
Adhesive wear between casting steel parts
High maintenance costs
What to do?
How to prevent failure µ>0.1?
slide 742013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
The problem:High maintenance costs (wear by seizure)
The challenge: Find a tribo system (material combination)that sustains high contact pressures in sliding motion andshow minimal friction and minimal wear.
The solution: ?
slide 752013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
The solution: ?Only limited possibilities to modify the realized construction.
Alternative lubricant or coating system? Boundary Lubricated metal - metal contacts p<20MPa, µ>0.1 Thermoset – metal contacts p<150 MPa, µ>0.1 Polymer – metal contacts p<10 MPa, µ<0.1
slide 762013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
Polymer – metal contacts only for limited contact pressure?
Coulombs law: If the load is doubled the friction is doubled.Not for polymers!
slide 772013 RF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
PE against epoxy resin, p>150 MPa, µ=0.02…0.06F > 7000 kN (700 tonnes).
Cast steel
UHMWPE
Carbon fiber
Cast steel with epoxy coating
slide 782013 PF9 - Physics of Failure – Material Selection
Case study Storm surge Barrier
Testing of a special engineered turning cutter
slide 792013 RF9 - Physics of Failure – Material Selection
slide 802013 RF9 - Physics of Failure – Material Selection
500 holes in each ball joint
slide 812013 PF9 - Physics of Failure – Material Selection
slide 822013 RF9 - Physics of Failure – Material Selection
SummaryThe problem:
High maintenance costs (wear by seizure)The solution: Polymer discs, expansion blocked by
carbon fiber rings, sliding against epoxy coated steel surface.Performance: Contact pressures up to 150 MPa,
coefficient of friction μ < 0.05, lifetime > 5 km sliding distance, maintenance limited to overhauling of the epoxy coatingafter a large number of moves.
Case study Storm surge Barrier
slide 832013 RF9 - Physics of Failure – Material Selection
Material Selection
Summary• Several different material combinations have been
discussed with respect to their applications.• Metals, metal alloys, thermoplastics, thermosets,
ceramics and many coatings or surface treatments.• There is not an ideal material combination for
sliding contacts in general.• In machine design metal-metal combinations are
common and it is demonstrated that these combinationsneed to be lubricated.
RF9 Program Day 2
slide 84RF9 - Physics of Failure2013
9:00-9:15 Introduction
9:15-9:30 Friction related failures
9:30-10:00 Demo load capacity of sliding contacts
10:00-10:15 Break
10:30-11:30 PoF Friction
11:30-11:45 Application of gained results
11:45-12:30 PoF Wear
12:30-13:30 Lunch
13:30-14:00 Demo Dry Sliding and EP additives
14:00-15:00 PoF Material selection
15:00-15:15 Break
15:15-16:15 PoF Lubrication
16:15-16:45 Application of gained results
16:45-17:00 Summary of the day