An optimized biaxial stress temperature measurement for TiAlN based hard coatings

Research output: ThesisDiploma Thesis

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Abstract

The aim of this thesis was to determine the temperature dependence of the residual stresses in sputtered and arc evaporated titanium aluminium nitride based hard coatings deposited on single crystalline silicon substrates. The sputtered coatings were deposited with different bias voltages, whereas the arc evaporated coatings were deposited with two different Ti/Al ratios. Additionally, one arc evaporated coating for each Ti/Al ratio was doped with tantalum. The stress temperature behaviour was evaluated, using biaxial stress temperature measurements in high vacuum. As the experimental error during such measurements is comparatively high, it is necessary to achieve homogenous and reproducible temperature conditions. Therefore, an improved ceramic heating plate was installed and calibrated at the existing system. Thermographic measurements were used to determine the temperature conditions; a large temperature difference between heating plate and samples of up to several hundred degrees was observed. Tests at ambient pressure proposed that the temperature difference is 50 °C lower than in vacuum. By comparison with the melting points of indium, tin and lead reference materials, the exact temperatures of the samples were obtained. The coating samples showed uncommon disproportionate deformation during measurement at temperatures above 500°C. To calculate the maximum stress in the substrate, and to compare the value to the yield strength of silicon, a mechanical force and momentum equilibrium was established. Although the maximum stress was remarkably lower than the strength of silicon, plastic deformation could not be excluded.
Translated title of the contributionOptimierte Spannungs-Temperatur-Messung an harten Schichten basierend auf TiAlN
Original languageEnglish
QualificationDipl.-Ing.
Supervisors/Advisors
  • Mitterer, Christian, Supervisor (internal)
Award date4 Apr 2014
Publication statusPublished - 2014

Bibliographical note

embargoed until 17-02-2019

Keywords

  • TiAlN
  • biaxial stress temperature measurement
  • sputter deposition
  • arc evaporation
  • thermography
  • substrate plastification

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