XPS study of reactively sputtered Ti-B-N hard coatings

Abstract

Thin films (500 nm) of Ti–B–N have been produced by d.c. magnetron sputtering from a TiB2 target in various Ar+N2 gas mixtures. The atomic concentration of nitrogen in the films varies between 0 and 38 at.%. The ratio of boron to titanium in the films is fixed by the relative concentration of these two elements in the TiB2 sputtering target. Bonds of B–N, B–Ti, Ti–N and Ti–B are observed in the B 1s and the Ti 2p spectra. The change of shape observed in the N 1s spectra led to the conclusion that at low nitrogen concentration the nitrogen atoms are preferentially bonded with titanium atoms, in good agreement with thermodynamical data. By using quantitative information from the B 1s, Ti 2p and N 1s curve fittings, the formation of a film containing three separate phases (TiN, BN and TiB2) is discussed. Copyright © 2000 John Wiley & Sons, Ltd.

Characterization of nanostructured Ti–B–(N) coatings produced by direct current magnetron sputtering

“…It can be inferred from this comparative diagram that the target configuration and the gas flow mixture control the stoichiometry of the coatings, the former being predominant. In our case, a single type of Ti-B source (TiB 2 ) yields coatings richer in those elements, as has been reported previously [16].…”

“…Some attempts have been made by introducing nitrogen into the composition of the coatings. Early contributions of Novotny [7], in which the phase diagram of the Ti-B-(N) was well characterized, and more-recently published papers about film depositions using this ternary system [8][9][10][11][12][13][14][15][16], show the interest in investigating Ti-B-(N) coatings. This ternary system includes hard phases such as TiN, TiB 2 , B, and c-BN (cubic BN), and soft phases such as h-BN (hexagonal BN) and a-BN (amorphous-BN).…”

“…The sample prepared at the highest N 2 flow (F25-H1300) is near the TiN + BN binary system, which coincides with the XRD and EELS results, where almost no evidence of TiB 2 can be detected. The composition and trend presented by our samples as nitrogen increases are similar to those reported by Ruby et al [16] using an analogous route of synthesis. Moreover, the preferential formation of N-containing phases (BN and TiN) can explain well the observed reduction of crystal size when N 2 is added.…”

“…Furthermore, a random orientation of the crystalline phase is inferred from the corresponding XRD spectra. The broadening of the (100) diffraction peak shows the crystallite size is reduced from 10-20 nm for the coatings prepared using pure Ar flow to 5 nm for the coatings prepared with Ar/N 2 mixtures (see Table 1), as also reported by Ruby et al [16] for similar synthesis conditions. When N 2 is introduced into the chamber, the number of charged species in the plasma (ions and electrons) decreases due to the energy "wasted" in the excitation of vibrational modes of N 2 species.…”

Influence of pulse frequency and bias on microstructure and mechanical properties of TiB2 coatings deposited by high power impulse magnetron sputtering

“…6 are therefore considered representative for all coatings. The main peak at 187.9 eV is attributed to B in the TiB2 phase [27,28]. The TEM analysis implied the existence of a B-rich tissue phase in the TiB2 grain boundaries and a contribution from B-B bonds is therefore expected in the B1s spectra.…”