Excellence in Nanomechanical Test Instrumentation

Nano-Impact and Fatigue Measurements

The patented nano-impact technique from MML is an accelerated ultra-low load fatigue wear test capable of revealing differences in performance that can be used to optimise the design of new thin films and coatings for improved durability. Instead of simply "characterizing" new coatings and thin films, their actual tribological performance under "in service" conditions can be assessed.

Traditional nano-indentation and mechanical property measurements use static loads, even though materials fail by fatigue at lower loads than predicted by these static tests. By offering the nano-Impact technology, MML have allowed the reproduction of 'in-service' conditions. This technique allows films that show similar hardness and modulus to be clearly differentiated in terms of wear resistance in service if adhesion-promoting interlayers are used.

High and low cycle fatigue tests over a wide range of contact stresses, frequencies, test durations and strain rates are all possible in the nano-impact test. Single impacts with the pendulum impulse set-up can be used to measure dynamic hardness. For multiple impact tests, the time to failure, mechanism of failure, energy to failure, and probability of failure at a given load can all be studied.

MML offer two unique methods of nano-impact measurement

1. Sample Oscillation
The sample is oscillated by means of a piezoelectric oscillator.

nano-impact

Experimental variables include:

Applied Load

Oscillation frequency

Oscillation Amplitude

Sample scanning

Probe geometryImpact Angle

The high frequency oscillation available with this method allows high cycle fatigue investigations to be made, and is useful for the investigation of the fatigue properties of metals, ceramics, tool coatings and polymers. In addition, time-to-failure, adhesion failure and fracture behaviour can be assessed.

2. Pendulum Impulse Impact
Using this method, the pendulum is pulled back and released to allow a controlled impact.

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Experimental variables include:

Static Force

Impact Angle

Acceleration distance

Impact Frequency

                                                                            Test probe geometry

This impulse method is very useful for low cycle fatigue and allows the durability (toughness) of the material to be assessed as well as its mode of failure.

In addition dynamic hardness testing is possible. This method allows the quantification of adhesion energy, determination of total energy delivered to contact point, and high strain rate (dynamic) hardness measurements.

Further Reading
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