Thermal stability of sputter deposited nanocrystalline W2N/amorphous Si3N4 coatings

Abstract

The thermal stability of nanocomposite W-Si-N coatings, which had been sputter deposited at increased silicon target currents, was studied by annealing at 800 or 900°C in vacuum by using x-ray diffraction, x-ray photoelectron spectroscopy, electron probe microanalysis, scanning electron microscopy, atomic force microscopy, and microhardness testing. The crystalline W 2 N coatings were decomposed to W with the loss of interstitial N atoms and the presence of microcracks at their surfaces after annealing at 900°C. The coating consisting of nanocrystalline ͑nc-͒ W 2 N imbedded in amorphous ͑a-͒ Si 3 N 4 matrices and the amorphous coatings underwent partial recrystallization, the loss of interstitial N atoms, and morphological changes upon annealing. The nc-W 2 N/a-Si 3 N 4 coating had the least N in grain boundaries and the lowest atomic O / N ratio, and it had no failure after annealing at 900°C, showing high thermal stability. The hardness of the coatings was decreased, but the nc-W 2 N/a-Si 3 N 4 coating maintained the highest hardness ͑46.6± 3.7 GPa͒ after annealing at 900°C.

Effects of W Content on Structural and Mechanical Properties of TaWN Films

“…The low sity of W-N bonds indicated the low affinity between W and N atoms. The binding e values of W 4f7/2 for the W-W and W-N bonds in the fabricated TaWN films were 31.44 and 32.27-33.05 eV, respectively, which were comparable to the reported 31. eV for W films and 32.1-33.1 eV for W-N bonds[49][50][51][52]. The N 1s signals compris…”