The Advanced Materials Show 2019 presentation

1. Metrology and Engineered Surfaces
M G Gee
National Physical Laboratory
11th July 2019
Advanced Materials Show

2. About NPL …
The UK’s national standards laboratory
• Founded in 1900
• World leading National Measurement
Institute
• ~1000 staff; 550+ specialists in Measurement
Science plus 200 visiting researchers pa
• State-of-the-art laboratory facilities
• 388 Laboratories (35,746 sq. metres)
• The heart of the UK’s National Measurement
System to support business and society
• Experts in Knowledge Transfer

3. Our Labs

4. Our Sector Focus
Digital
Life Sciences & Health Advanced Manufacturing
Environment & Energy

5. 5
Engineered Surfaces
▪ Engineering Surfaces can potentially provide major improvements
in the properties and performance of components:
⬧ Mechanical
- Wear
Decrease - most rubbing surfaces in equipment, abrasion resistant
Control - abradable seals in aero engines
Increase - when used in manufacturing (grinding, polishing)
- Friction
Increase - anti-slip surfaces
Control - brakes
Decrease - efficient engines
⬧ Chemical
- High Temperatures
Oxidation - power plant
Corrosion - power plant
Direct reaction - cutting tools
- Low temperatures
Corrosion – bridges

6. 6
Engineered Surfaces
- Physical
Electrical - lacquer on wires, generating plant
Thermal - TBCs on turbine blades
Optical - anti reflectance coatings on lenses
- Decorative
Taps
Jewelry
▪ To design effective surface engineering solutions we require good
data for design
▪ Good data is also needed to implement the conversion of
manufacturing to digital manufacturing

7. Right First Time
7
Stable process enables DFM
- Predictive outcome
- Early problem identification
- Solution when costs and impact are low

8. 8
Measurement
▪ Three approaches to measurement
▪ Assess operating conditions in application, extract key conditions, model and then measure
important parameters to achieve prediction of performance
▪ Issues: reliability of extracting key parameters, difficulty in modelling, choice of important
parameters, extrapolation is difficult, but can be much cheaper
▪ Reproduce operating conditions exactly so that good reliable simulation performance can be
achieved
▪ Issues: can we reproduce operating conditions well enough, can be very expensive
▪ Try it and see (field testing)
▪ Issues: Often doesn’t work, so repeated iterations are expensive, in many cases you cannot do
this for safety etc reasons

9. 9
Coatings Measurement
▪ Measurements needed in areas such as:
⬧ Thickness
⬧ Chemistry
⬧ Microstructure
⬧ Strength and adhesion
⬧ Hardness and elastic properties
⬧ Measuring wear and friction
⬧ Durability
⬧ Residual stress
▪ Some of these properties are surprisingly difficult to
measure, e.g. adhesion
▪ Aim is to make measurements simpler, more
relevant, cheaper, more robust
▪ Standardisation can give improved framework for
measurements

10. 10
Video
Acoustic emission
Strain gauge
Load cell
Rollers
Motor drive
Displacement Sensor
Measuring Coating Integrity by Bend Testing
Context
▪ Need to provide information
on integrity of coatings
under mechanical loading
Science
▪ Use instrumented bend
testing
▪ Acoustic emission
▪ Video to detect cracking
Future Vision
▪ Is being taken forward into
work to provide simple test
for near shop floor
environment
▪ Proposal for standardisation
in CEN

11. 11
Bend Testing - Comparison of Samples
Hydroxyapatite
Chromium Carbide: Fine Ground
Chromium Carbide: Coarse Ground
Tungsten Carbide: Fine Ground
Tungsten Carbide: Coarse Ground
Hard Chrome
Codeposited Electroplate

12. 12
Scratch Testing
acoustic
emission
tangential
force
load
optical
inspection
of failure modes
acoustic
emission
tangential
force
load
optical
inspection
of failure modes
0 20 40 60 80 100
0
10
20
30
40
FrictionForce,N
Load, N
0 20 40 60 80 100
20
30
40
50
60
70
80
AESignal,dB
Applied load, N
Lc = 21.3 NLc = 21.3 N

13. Advanced Characterisation
Miniaturised Testing – Influence of sample size
▪ Nano indention
▪ Hot Hardness
▪ Micro test specimens

14. NPL Integrated Tribometer
▪ Pin-on-disc system
▪ Loaded through lever system below machine table or actuator system
▪ Allows unrestricted access for multiple sensors
▪ Current focus on linescan camera for visual imaging and multipoint
chromatic aberration probe for real time profilometry
⬧ Multipoint probe can measure 180 point profile at 2kHz rate
Overall view Close up

15. Schematic of Layout
Chromatic
aberration
probe
Wear track
Linescan camera
Pin
Self zeroing friction
and normal
force measurement
4 images per revolution
Interval for capture selected by user
Top view of layout
Scanning through
rotation of disc
Final image
Schematic of self zeroing friction device

16. Steel Ball on Alumina Flat (Dry), 200 N
Real -
time
Height
Map
Real -
time
Optical
Image

17. Confocal Microscopy of Steel on Alumina
Confocal Intensity Height Image

18. In situ Scratching
▪ Need to get improved understanding
of mechanisms of abrasion
▪ Simulate abrasion through
experiments using microtribometer to
carry out scratches to impose damage
into hardmetals
▪ Types of experiments
⬧ Single position, multiple position
⬧ Static load, ramping load
⬧ Different radius diamond indenter
⬧ Different environments (dry and acidic)
▪ Explore damage using optical
microscopy, SEM, and FIB-SEM
▪ Ex situ and In situ
direction multi-position
load profile
NPL microtribometer
Indenter geometry

19. Experiment in progress

20. Uncoated Tool Steel 100 mN 1µm Indenter

21. DLC Coated Tool Steel 100 mN 1µm Indenter

22. Standardisation
▪ NPL is involved with 3 different international standards organisations, ASTM,
CEN and ISO
▪ Many committees relevant to Surface Technology:
⬧ ISO TC 164 Machanical Testing of Metals
- Hardness and nanoindentation
⬧ ISO TC 156 - Corrosion of metals and alloys
- Galvanising, high temperature degradation, aqueous corrosion, erosion/corrosion
⬧ ISO TC 206 – Fine ceramics
- TBC, PVD coatings, Wear standards, Scratch Testing
⬧ ISO TC 107 – Metallic and other inorganic coatings
- TBC, PVD coatings, Wear standards
⬧ ASTM G2
- Wear and friction

23. 23
To Sum Up
▪ Wide range of measurement methods available
▪ Range of accessibity
▪ Need to think about relevance of measurements to applications
▪ NPL is available to help