Title : Effect of the N2 and C2H2 mass flow rates on the corrosion properties of TiSiCN coatings
Abstract:
The objective of the present study was to enhance the quality of cutting tools used in wood industry, where working parts and tools are subjected to severe conditions. TiSi-based carbo-nitrides were deposited by cathodic arc evaporation using TiSi cathodes with 99.9% purity. The coatings were deposited simultaneously on 2-inch Si (100) wafer (0.8 mm thickness, 50.8 mm diameter) and three types of steel (?= 20 mm), depending on the analysis carried out. The metallic substrates were X155CrVMo12 alloy (elemental composition, at. %: 1.53 C, 0.35 Si, 0.40 Mn, 12 Cr, 1 Mo, 0.85 V), 16MnCr5 alloy (elemental composition, at. %: 0.14-0.19 C, 0.4 Si, 1-1.3 Mn, 0.025 P, 0.035 S, 0.8-1.1 Cr) and C45 alloy (elemental composition, at. %: 0.43-0.50 C, 0.60-0.90 Mn, 0.04 P, 0.050 S).
The deposition conditions were fixed: 2 x 10-3 Pa residual pressure, 6 x 10-2 Pa working pressure, -200 V substrate bias and 90 A arc current. To obtain coatings with different composition, the N2 and C2H2 mass flow rates were varied such as four sets of samples were fabricated: series-1 (20 sccm Ar, 110 sccm C2H2), series-2 (40 sccm Ar, 90 sccm C2H2), series-3 (80 sccm Ar, 50 sccm C2H2), and series-4 (110 sccm Ar, 20 sccm C2H2).
Surface morphology, elemental/phase composition and roughness were investigated before and after corrosion process evaluation. There is an increasing tendency of nitrogen concentration (ranging from ~2 to ~26 at. %) detrimental to carbon content (ranging from ~53 to ~21 at. %), in correlation with the reactive atmosphere of the deposition process. For the coatings, a gradual increase is visible for the (200) oriented peak located at ~59°. Above 26 at. % nitrogen the preferred orientation of the TiC/TiN phase was changed to (111) plane, inducing modification in crystalline growth, most probably due to the competition between surface and strain energy. The results showed that TiSiCN coatings improved the corrosion resistance of the uncoated alloys. Moreover, an increase in the nitrogen flow rate during the deposition had a positive influence on their electrochemical behaviour, regardless of the type of substrate.
This research was supported by a grant of the Ministry of Research, Innovation and Digitization, project number COFUND-M-ERANET-3-HardCoat-1 (no.311/2022), within PNCDI III and Romanian National Core Program no.PN11N-03-01-2023.
Audience Take Away:
- The service life of cutting tools used in wood industry will be improved by these coatings.
- The knowledge related to correlation between properties and functional performance.
- The proposed coatings can also be used for other applications.
