Thermal Evolution of WC/C Nanostructured Coatings by Raman and In Situ XRD Analysis

In this work, a series of WC/C nanostructured films were deposited on silicon substrates by changing the ratio of sputtering power applied to graphite and WC magnetron sources (PC/PWC: 0, 0.1, 0.5, 1). The thermal stability of WC/C coatings was followed in situ by means of X‐ray diffraction measurem...

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Bibliographic Details
Published in:Plasma processes and polymers 2009-06, Vol.6 (S1), p.S444-S449
Main Authors: Mrabet, Said El, Abad, Manuel David, López-Cartes, Carlos, Martínez-Martínez, Diego, Sánchez-López, Juan Carlos
Format: Article
Language:English
Subjects:
annealing
Carbides
Carbon
Coatings
Deposition
Fittings
nanocomposite coatings
Nanostructure
Phases
Polycarbonates
Raman spectroscopy
Thermal stability
Tungsten carbide
X-ray diffraction
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Summary:In this work, a series of WC/C nanostructured films were deposited on silicon substrates by changing the ratio of sputtering power applied to graphite and WC magnetron sources (PC/PWC: 0, 0.1, 0.5, 1). The thermal stability of WC/C coatings was followed in situ by means of X‐ray diffraction measurements up to 1 100 °C in vacuum (10−1 Pa). Initially, the film microstructure is composed of nanocrystalline WC1−x and W2C phases. As the PC/PWC ratio increases the crystallinity decreases, and WC1−x becomes the predominant phase from PC/PWC = 0.1. The results show that the structural evolution with temperature of all studied layers depends essentially on their initial phase and chemical composition (determined by the synthesis conditions: ratio PC/PWC). The coating deposited at PC/PWC = 0 reveals a transformation of W2C phase into W and W3C phases at 400 °C. However, the samples with PC/PWC greater than 0 exhibits an improved thermal stability up to 600–700 °C where the WC1−x begins to transform into W2C and WC phases. At 900 °C, WC is the predominant phase, especially for those coatings prepared with higher ratios. Further annealing above 1 000 °C yields W as the foremost phase. The thermal behaviour was later studied by means of Raman spectroscopy measurements at certain temperatures where the main changes in phase composition were observed. Particularly, a fitting analysis was carried out on the D and G bands typical of disordered and amorphous carbon. The changes induced during heating are discussed in terms of the positions of D and G lines, and full width at half maximum (FWHM).
ISSN:1612-8850
1612-8869
DOI:10.1002/ppap.200931004