Scratch testing is a technique used to characterize interfacial adhesion and wear resistance of coatings and thin films. Scratch testing is an invaluable tool in many industries – from automotive for its ability to quantify interfacial adhesion of paints to manufacturing for measuring the wear resistance which hard coatings impart onto critical components. A scratch test is performed by dragging a diamond tipped probe across a sample under a constant or increasing load. Parameters such as tangential force, penetration depth, and acoustic emission are recorded during a test, and significant fluctuations in their behavior indicate a failure event has occurred. Failure events can be categorized by correlating parameter data with optical microscopy images (i.e. cohesive or adhesive failure), giving key insights into the root cause of potential coating failures.

The Revetest Macro Scratch Tester, manufactured by Anton-Paar (formerly by CSM Instruments), is a high load scratch tester ideally designed to test hard coatings such as TiN, TiC, and DLC. The Revetest Macro Scratch Tester can apply a maximum load of 200 N during a scratch or indentation test which makes it ideal for studying the failure mechanisms of hard coatings or surfaces of bulk materials. Utilizing the Revetest’s ability to synchronize optical microscopy images with sensor data along the entire scratch track, this instrument can quantify different failure events within the same sample accurately and precisely. This matching of optical microscopy data with these unique failure events can lead to a better understanding of the interfacial adhesion and wear properties of a coating/substrate system.

Typical Experimental Results

Scratch parameter curves of a TiN coating on steel undergoing a scratch measurement. The vertical gray line indicates the critical force of interfacial adhesion failure.
Optical image of a TiN coating on steel sample post scratch test. The chipping in the coating is indicative of interfacial adhesion failure taking place.
Optical image of a TiN coated steel sample at the end of a scratch track. The gross spallation and exposure of the steel substrate indicate that severe interfacial adhesion failure has occurred.
Optical image of a diamond like carbon (DLC) coated steel sample after a scratch test. The cracking along the edges of the scratch track and exposure of steel substrate indicate continous adhesion failiure has begun within the coating.
Panoramic picture of a scratch on TiN using a 20x objective lens.

Applications

Adhesion
Testing 		Alloys Bonding Ceramics
Coatings Delamination Failure Analysis Films
Interfaces Materials Metals Polymers
Scratch Testing Surface Free
Energy 		Tribology Wear

For more information please read our application notes:

Scratch Interfacial Adhesion Failure of TiN Coatings on a Steel Substrate

Instrument: Anton Parr Revetest
(Formerly Known as CSM Instruments) Macro Scratch Tester

Key Specifications

Maximum Load 200 N
Load Resolution 100 µN
Loading Rate 0.4 to 300 N/min
Depth Range 1000 µm
Depth Resolution 0.05 nm
Data Acquisition Rate 192 kHz
Scratch Speed 0.4 to 600 mm/min
ASTM Number Title Website Link
C1624-05(2005) Standard Test Method for
Adhesion Strength and
Mechanical Failure Modes of
Ceramic Coatings by Quantitative
Single Point Scratch Testing		 Link
D7027-13 Standard Test Method for
Evaluation of Scratch Resistance
of Polymeric Coatings and Plastics
Using an Instrumented Scratch
Machine		 Link
D7187-15 Standard Test Method for
Measuring Mechanistic Aspects
of Scratch/Mar Behavior of Paint
Coatings by Nanoscratching		 Link
F2496-05(2011)e1 Standard Practice for Determining
the Scratch Hardness and Scrape
Adhesion of Prints and Coatings		 Link
F548 – 09(2014) Standard Test Method for Intensity
of Scratches on Aerospace
Transparent Plastics		 Link
G171 – 03(2017) Standard Test Method for Scratch
Hardness of Materials Using a
Diamond Stylus		 Link
ISO Number Title Website Link
1518-1:2011 Paints and varnishes — Determination of
scratch resistance — Part 1:
Constant-loading method		 Link
1518-2:2011 Paints and varnishes — Determination of
scratch resistance — Part 2:
Variable-loading method		 Link
15695:2000 Vitreous and porcelain enamels —
Determination of scratch resistance
of enamel finishes		 Link
17541:2014 Plastics — Quantitative evaluation of
scratch-induced damage and
scratch visibility		 Link
18922:2003 Imaging materials — Processed
photographic films — Methods for
determining scratch resistance		 Link
19252:2008 Plastics — Determination of scratch
properties		 Link
20502:2005 Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Determination of adhesion of ceramic
coatings by scratch testing		 Link
27307:2015 Thermal spraying — Evaluation of
adhesion/cohesion of thermal sprayed
ceramic coatings by transverse
scratch testing		 Link