VTT TECHNICAL RESEARCH CENTRE OF FINLAND LTD

Tribology research facilities at VTT

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Sliding contact Rotational sliding contact (pin-on-disc)Reciprocating linear sliding contact (rec-tester, piston ring tribometer) Dry or lubricated, controlled conditions (relative humidity, temperature 20 - 500 oC )

Rolling contactTwin-disc tribometer (Amsler)Dry or lubricated, temperature 20 - 70 oC

Coating properties Scratch test for coating adhesionCoating thickness (ball cratering test)

Abrasive wearRubber wheel test, micro abrasion, scratch test

Slurry erosion testBearing test rigs

Journal bearing, rolling element bearingPiston ring tribometerLubricant properties and performance

Lubricant film thickness (optical interferometer)Viscosity (viscosimeter)

Contaminants in lubricantFerrography, particle counter, particles in grease

Various characterization and analysis methods (profilometry, microscopy, SEM/EDS, AFM, micro scratch tester, instrumented indentation, hardness, …)

VTT Tribology laboratory test facilities

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A method for evaluation of friction and wear in slidingcontact between surfaces of bulk materials and/orsurface coatings.

In a test a stationary test specimen pin or ball is loaded with normal force against the surface of a rotating disc.Friction force is measured during the test.Wear of the test specimens is determined afterwards by weighing, microscopy or profilometry. Wear measurement during the test is possible with proximity measurement.Tests can be performed with or without lubrication. Sliding velocity, surface pressure, and temperature can be selected to match the application under study.

The VTTPOD2 pin-on-disc test unit, one of the four at VTT.

Pin-on-disc (1/3)

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Normal force 2 - 100 N

Rotational velocity 10 - 3000 rpm

Sliding velocity 0,02 - 12 m/s depending onrotating velocity and sliding diameter.

Temperature and relative humidity

The tests are performed in a test room where the temperature is 22 1 oCand relative humidity is adjustable between 40 and 60 %. High temperaturepin-on-disc test equipment is equipped with an oven so that temperatures ashigh as +500 °C can be reached. Also, tests in a gas atmosphere arepossible.

Lubrication Oil, water, or grease lubrication can be applied when low rotation speeds are used.

Test parameters and environment

Pin-on-disc (2/3)

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CSM Instruments Pin-on-Disk Tribometer

Rotation speed: 0.03 – 1500 rpmStandard loads: 0.10 N – 60 NDisk diameter: up to 60 mmFriction force: up to 20 N

Environmental chamber (for inert gasses)Multi cycle angular reciprocating modeLiquid cup for linear reciprocating mode

CSM POD tribometer can be used for tribocorrosion experiments

Pin-on-disc (3/3)

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Static friction tribometer

Static Friction Tribometer is designedand developed at VTT

Normal load from 10 N to 200 N

Temperature from RT to 300 °C

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Normal force 5 - 100 N

Sliding velocity 0.05 - 100 mm/s

Maximum lenght 100 mm

Maximum frequency 1 Hz

Lubrication Water or oil lubrication can be applied.

Temperature Room temperature (22 1 oC) or elevated disc temperature, max +150 oC.

Relative humidity Standard air-conditioned test room, relative humidity adjustable 40 - 60 %.

A method for evaluation of friction and wear characteristics of materials and surface coatings.

An example of test arrangement where the cylindrical test specimens are sliding

crosswise.

Test specimens

Resiprocating sliding test

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test disc in oil bath

ball holder

vibration transducer

AE-transducer

ball

AE RMS and Friction coefficient curves

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0,095

0,10,1050,11

0,1150,12

0,125

Time [h]

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0,01

0,02

0,03

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0,05

AE

[V]

FrictioncoefficientAE [V]

AE

Friction

Fric

tion

coef

ficie

nt

Lubricant performance testing e.g. by comparison of differentlubricants with respect to frictional and wear behaviour

Test in oil bath => friction and wear with time, possibility to stepwise increasing load or sliding speedTest with lubricant addition in the beginning but no addition duringtest => time to an increase in friction

Instrumentation of the equipment possible

Lubricant performance testing in POD orRectester

901/10/2015 9

Possibility for experimental research of friction and wear of different material combinations in situations where the load and rotational speed are well known.

Also lubricant properties at elevated temperatures.

The rotational speeds of the shafts are continuously and independently adjustable within the 20 - 2000 rpm range, so the slip can vary from 0 to 100 %.

The load between the test specimens can vary from 100 to 2000 Newtons.

A test method for researching different material combinations, friction and lubricant properties in rolling and/or sliding contact.

Twin-disc

1001/10/2015 10

Equipment for friction and wear measurements on piston ring and cylinder liner combinations.

Normal load max 500 N Reciprocating frequency 5-44 Hz (300-2640 rpm)Amplitude 40 mm, crank shaft drivenMax. mean piston ring velocity 3.2 m/sMax. piston ring velocity 5 m/sTemperature from room temperature to 250ºC.Mass force compensated measurement of the friction force, from the piston ring sample, 500 measurements per crankshaft revolution (in sets at fixed intervals).Electronically controlled lubricating oil supply (all oils allowed).

Coefficient of frictionSurface texture alterations Wear on ring and linerOil film thickness in the ring/liner contactTemperature at the sliding surface

Piston ring sample length 20 mmCylinder liner sample 30X60 mm

Piston ring tribometer

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Test equipment for sliding contacts, particularly for experimental research on journal bearings.

The geometry, speed and load bring particular requirements to the experimental research on journal bearings.

Possibility to study material combinations for journal bearings and other sliding contacts under a wide range of loads speeds and lubricants.

The friction and wear behaviour of the material couple is studied.

Other parameters that can be measured are the bearing temperature, the lubricant film thickness, vibrations, the oil film pressure and the lubricant flow rate.

Journal bearing test

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Provides a possibility to research rolling bearings under various loads, lubrication types and temperatures.

Failure progression monitoringMonitoring of lubrication conditionAccelerated wear tests with added impurities

Circulating or bath lubrication (oil)Grease lubrication also possibleRotation speed 100-2500 rpmRadial load 200-15 000 NTemperature max. 65°C.

Rolling bearing test rig

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The scratch adhesion test is a method for evaluating the adhesion of thin and thick hard coatings. Scratch tests can be exploited in development and quality control of coatings.

Suitable for a range of coated machine parts and tools with a coating thickness of 0.3 - 20 µm.

Requires a flat or cylindrical area with a size of approx. 1 cm2 which needs to be easily inspected.

The maximum size of the test specimen is 100 x 150 x 50 mm.

The scratch test can also be used as an instrument to study abrasive wear mechanism under controlled conditions the diamond stylus being the abrasive 'particle'

Coated test specimen.

Diamond stylus Diamond stylus

Scratch test

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Micro Combi Tester (MCT)

Antor Paar TriTec Micro Combi Tester combines the capabilities of Micro Indentation Tester and Micro Scratch Tester

Maximum normal load 30NSliding speed from 0.1mm/min to 600mm/minMaximum depth is 1000µmMaximum friction force is 30N

Micro Combi Tester can measure friction, acoustic emission, tip displacement andcritical surface failure loads. In addition, panoramic images of wear scars can be taken.

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An Ultra Nano Indentation Tester (UNHT) devicecan be used to investigate the mechanicalproperties of materials in micro- and nanoscalewithout worrying about thermal drift.

The device is well suited for long-termmeasurements on all types of materials, includingpolymers, very thin layers and soft tissues.

Integrated to the device there is an opticalmicroscope. Separate AFM and SEM devices canbe used to investigate the indentation marks.

Nanoindentation

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A microscopic image of a crater through a coating.

Coating thickness is

where X and Y are the dimensions determined with a microscope, and D is the diameter of the ball.

A nearly non-destructive method for evaluation of coating thickness. Suitable for allhard coatings of thickness 0.5 - 10 µm.Suitable also for microabrasion studies; diamond paste is used as abrasiveReliable measurement of the coating thickness less than 1um requires Ra-value less than 0.2 um.

DYX

Ball cratering test

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Optical interferometry is a method for measuring the filmthickness and friction coefficient of lubricants.

Contact pressure, max 1.8 GpaSpeed, max. 1.6 m/sSliding ratio 0-100 %Temperature 20-85 °C

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300

0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80

Speed [m/s]

Film

thic

knes

s [n

m]

Central film thickness hc [nm] Minimum film thickness hmin [nm]

Lubricant film thickness

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A wear particle analysis for qualitative and quantitativedetermination of contaminant particles in lubricationoil and grease.

Different contaminants and wear particlesAmount, size, shape and type

Contamination level of the lubricantCondition of the system.

Ferrography analysis

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A condition monitoring research method to define the number and size distributionof contamination in lubricant oil and grease.Suitable for all conventional mineral oils, synthetic lubrication oils and mineral oilbasis lubrication greases.

PAMAS SBSS-C analyzerStandards ISO 11171 and ISO 4402

Automatic particle counter

2001/10/2015 20

The cleanliness of lubricating grease is a measure of the lubrication ability of the grease and an indicator of the wearsituation of the lubricated components

VTT has developed an instrument for measuring the metal particle content in lubricating greases

The method is based on the change of impedance of a coil when exposed to a sample of grease, containing metalparticles

Lubricating grease metal particle analyzer

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