Entwicklung von Hartstoffschichten auf Chrom-Basis mit Hilfe der Pulsed Laser Deposition
Research output: Thesis › Diploma Thesis
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Abstract
Oxygen is usually found as a contaminating species in chromium (Cr) and chromium nitride (CrNx) coatings grown by various physical vapour deposition (PVD) techniques (e.g. sputtering, arc evaporation). The current work shows that the high energetic pulsed plasma conditions in the Pulsed Laser Deposition (PLD) technique intensify the oxygen trapping in Cr and CrNx coatings and strongly influence their microstructure. Cr-based coatings were deposited by an industrially designed 4-beam PLD evaporation system at room temperature (25 °C) by using Nd:YAG laser radiation (wavelength: 1064 nm) for Cr target ablation in N2/Ar gas mixtures. Due to the decrease of the oxygen content in films of higher thickness the source of O2 was found to be the rest gas atmosphere after evacuation to pressures lower than 0.002 Pa. Coatings deposited from the pure metallic Cr targets in Ar rich atmospheres possess a very fine-grained alpha-Cr phase structure with strongly increased lattice parameters resulting from the exchange of Cr by O atoms on bcc lattice sites. In contrast, high N2 contents in the deposition atmosphere result in the predominant formation of face-centered cubic CrN mixed with rhombohedral Cr2O3.
Details
Translated title of the contribution | Development of hard coatings based on chromium by employing pulsed laser deposition |
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Original language | German |
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Award date | 7 Apr 2006 |
Publication status | Published - 2006 |