Using Nanomechanical Testing to Optimise Hard Coatings on Machine Tooling

By AZoNano Editors

Table of Contents

Introduction

It is possible to optimize coatings using rapid, rigorous testing. Machining at high speeds causes a high level of stress on tools used for the cutting process. The coating microstructure is optimized in such a way as to obtain the right combination of hardness and toughness to make sure the materials continue performing. Yet the broad range of conditions under which they will function makes this a highly complicated requirement.

Tests for Hard Coatings

Based on the functions that hard coatings need to fulfill, performance factors such as oxidation resistance, thermal stability and hot hardness need to be built in. The next step would be to test coatings against factors such as wear, friction, oxidation, thermal cycling and adhesive interaction. It is impossible to have a test for all these factors and conditions in a macro-scale test environment. But it is made possible with the NanoTest Vantage.

NanoTest Vantage

The NanoTest Vantage system from Micro Materials combines several nanomechanical testing techniques into a single instrument. It can also operate at temperatures up to 750°C which means that it is being used increasingly to characterize high temperature and high performance materials and components such as airframes and avionics across the aerospace industry.

The NanoTest Vantage from Micro Materials

Nanomechanical Testing

Nanomechanical testing is possible with the NanoTest Vantage and enables the assessment of all important factors especially the three major interlinked factors such as hot hardness, plasticity and fatigue fracture resistance. Savings in time and materials are enormous, enabling engineers to design and manufacture new tools quickly and competitively.

Carbide Tool Life

It is important to have both toughness and hardness for severe mechanical contact applications. Even very slight changes to the percentage binder and carbide grain size in cemented carbides can have a drastic influence on tool life. Fatigue performance is controlled by sub-surface mechanical properties under highly loaded applications, such as high performance stamping. Hence microindentation is used to determine the mechanical characteristics of different cemented carbides.

The figure shows how the plasticity index, which is the ratio of plastic energy to total energy in indentation, changes with indentation load. There is an excellent correlation between the microindentation data and the wear rate. Lower plasticity results in chipping in wear tests and higher wear rate.

Plasticity index

Conclusion

The optimization of hard coatings is possible using comprehensive nanomechanical tests with the NanoTest Vantage.

About Micro Materials

Established in 1988 Micro Materials has continually been at the forefront of innovation, with our pioneering approach leading to three world firsts:

• The first commercial nanoscale impact tester, for erosive wear, toughness and contact fatigue.
• The first commercial high temperature nanoindentation stage, capable of reaching temperatures up to 750°C.
• The first liquid cell, allowing the testing of samples which are fully immersed in a fluid.

Micro Materials provide innovative, versatile nanomechanical test instrumentation, and respond to developments in applications in response to customer and market requirements. The integrity, reliability and accuracy of our equipment is paramount, as is our relationship with our users.

This information has been sourced, reviewed and adapted from materials provided by Micro Materials.

For more information on this source, please visit Micro Materials