Semi-quantitative chemical analysis of hard coatings by Raman micro-spectroscopy: the aluminium chromium nitride system as an example

• Published in: Analytical and bioanalytical chemistry Vol. 389; no. 5; pp. 1569 - 1576
• Main Authors: Kaindl, R, Sartory, B, Neidhardt, J, Franz, R, Reiter, A, Polcik, P, Tessadri, R, Mitterer, C
• Format: Journal Article
• Language: English
• Published: Germany Berlin/Heidelberg : Springer-Verlag 01.11.2007
• Subjects: Chemometrics/Statistics; Electron/ion microprobe; Inorganic compounds/Trace inorganic compounds; instrumentation; IR spectroscopy/Raman spectroscopy; Metals/Heavy metals; Thin films
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-007-1540-4

A new method for chemical analyses of nitride-based hard coatings is presented. Raman band shifts in the spectra of Al x Cr₁-x N coatings, deposited by physical vapour deposition from Al x Cr₁-x targets with x T,Al = 0, 0.25, 0.50, 0.70 and 0.85, are calibrated using compositional data of the coatings derived by elastic recoil detection analysis (ERDA) and electron probe micro-analysis (EPMA). Inserting the composition-dependent Raman shift of a combinatorial acoustic-optic lattice mode into an empirically derived equation allows the determination of Al/Cr ratios of the coating with an accuracy of about ±2%. Spot, line and area analyses of coated cemented carbide and cold work steel samples by using a computer-controlled, motorized x,y-stage are demonstrated and the most important errors influencing precision and accuracy are discussed. [graphic removed]