Residual stresses and thermal fatigue in CrN hard coatings characterized by high-temperature synchrotron X-ray diffraction
| Autor: | Christoph Kirchlechner, Manuela Klaus, Ch. Genzel, Klaus J. Martinschitz, Jozef Keckes, Christian Mitterer, Rostislav Daniel |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Hard metal
Materials science Scanning electron microscope business.industry Metals and Alloys Surfaces and Interfaces engineering.material Atmospheric temperature range Focused ion beam Surfaces Coatings and Films Electronic Optical and Magnetic Materials Optics Coating Sputtering Residual stress Materials Chemistry engineering Stress relaxation Composite material business |
| Zdroj: | Thin Solid Films. 518:2090-2096 |
| ISSN: | 0040-6090 |
| DOI: | 10.1016/j.tsf.2009.08.011 |
| Popis: | The aim of this work is to analyze thermal fatigue in hard coatings/substrate composites (i) during slow heating and cooling and (ii) after local cyclic thermal laser pulse experiments. As a model system, CrN coatings with a thickness of 3 µm deposited on steel, hard metal and Si(100) substrates using reactive magnetron sputtering at a temperature of 350 °C are used. The coatings are at first characterized by means of in-situ high-temperature X-ray diffraction (XRD) using a commercially available temperature attachment and by applying heating and cooling rates of less than 0.3 °C/s. The treatment results in the expected reduction of intrinsic stresses which are independent of substrate material but strongly influenced by substrate roughness. To simulate local thermal fatigue, selected coating/substrate composites are thermally cycled using a laser beam of 6 mm in diameter in a temperature range of 50–850 °C applying up to 10 4 cycles and using heating and cooling rates of about 10 3 °C/s. Subsequently, laser cycled samples are analyzed using synchrotron XRD, scanning electron microscopy and focused ion beam technique. Laser pulses cause a reduction of compressive stresses in the coatings and a development of tensile stresses in the substrates accompanied by formation of cracks and ripples. The results show that the changes of the local macro- and micro-strains/stresses in the coatings and in the underlying substrates are strongly interlinked. The stress relaxation in the coatings is caused by recovery effects, by micro-cracks formed in the tensely-stressed coating and by plastic deformation of the metallic substrates. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect