Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite CrC films

Influence of Nanoeffects on the Oxidation of Cr–C/Ag Thin Films Containing Silver Nanoparticles

“…(Examples of peak fits are shown in Figure b below, however in that case for the surface region instead of the bulk region but the principle is the same.) The carbon concentration in the a‐CrC x phase was 32 to 34 at.%, which is similar to that of the crystalline carbide phase Cr 7 C 3 and also in good agreement with previous results obtained for Cr−C films . Within this a‐CrC x /a‐C matrix, there were 2 to 5 nm large metallic Ag nanoclusters embedded (according to the previous transmission electron microscopy results).…”

“…This finding corresponds to a continuous oxidation process, which was particularly pronounced for the F 9 sample, containing the relatively small Ag NPs. The rapid increase in the current at potentials more positive than about +0.8 V (Figure a), which also was seen for sample A 0 , can mainly be ascribed to the oxidation of Cr 2 O 3 and CrC x yielding soluble Cr(VI) species, which is in good agreement with our previous findings for Cr−C films . Newly exposed Ag would also be oxidized in this potential region, but its contribution to the current should be relatively small, for two reasons.…”

“…The second set of chronoamperometric experiments made use of separate regions on a D 6 sample and involved potential steps to +0.25 or +0.50 V, each with a duration of 5 or 15 minutes. Both potentials were sufficiently high to oxidize the NPs (see Figure ) and the results of these experiments should hence mainly reflect differences in the rate of the oxidation of the exposed Cr−C (which should take place at potentials above about 0 V) . In the evaluation of the results, the total oxidation charges were employed.…”

“…While carbide and nitride nanocomposites can exhibit a high corrosion resistance, primarily due to the high stability of the corresponding metal oxide, these properties may be affected by the inclusion of Ag in the coatings. Two‐phase nanocomposite Cr−C films, consisting of amorphous chromium carbide and amorphous carbon (a‐CrC x /a‐C), have been shown to have high oxidation resistances in acidic solutions due to the formation of a passive layer composed of Cr 2 O 3 and a‐C, which protects the material from further oxidation . Since Ag is a noble metal, it could be expected that a Cr−C/Ag film likewise would exhibit a high corrosion resistance.…”

Synthesis and characterization of multicomponent (CrNbTaTiW)C films for increased hardness and corrosion resistance

“…Earlier studies have shown that HEAs in general exhibit improved corrosion resistance compared to stainless steel [17] although phase separation and chemical reactivity of the principal elements make these materials susceptible to pitting corrosion. We have in a recent study shown that CrC x films have very good corrosion properties [18]. It is possible that a multicomponent carbide can have even higher corrosion resistance than the corresponding HEA.…”