Depositions of decorative and wear resistant single layer coatings like TiN, Ti(B,N), CrN, NbN, NbON, (Ti,Mg)N and multilayer coatings like Cr/CrN, Nb/NbN, CrN/NbN and NbN/Nb-C:H were performed using reactive magnetron sputtering. The corrosion behaviour of the coated high speed steel substrates was studied in sodium chloride containing media by open-circuit-potential measurements, potentiodynamic corrosion tests and salt spray tests. Up to now, the best improvements with respect to the corrosion resistance in salt spray tests could be obtained for the system (Ti,Mg)N/high speed steel. 相似文献
Nitride TiN, TiAlN and CrN films exhibit a high performance with respect to steel corrosion protection in supercritical water. However, for practical applications their corrosion resistance in water solutions is more important. Wet corrosion of nitride PVD films in neutral, acid and alkaline supercritical solutions was studied. The highest stability of the films was revealed in neutral sodium chloride and alkaline CH3NH2 solutions. In the latter case regular cubic spinel crystals were formed on the surface of TiAlN films. Acidic solutions destroy nitride films due to growth of corrosion products beneath the coating layer. 相似文献
In this research, Cr(N)/C(DLC) multilayered coatings were deposited on M2 steel substrates by an unbalanced magnetron sputtering technique. By varying the substrate rotation speed, four multilayered coatings with different bilayer thickness were produced. The bilayer thickness and structure of multilayered coatings were characterized by low-angle XRD, XPS depth profile, and cross-section TEM observation. The tribological investigation focused on the effect of layer thickness and tribological media on tribological property of the multilayer coatings against Al counterface. A pin-on-disc tribometer with a tribological medium container was used to investigate the wear behaviours of the four multilayered coatings under dry and wet (distilled water and S500 coolant) sliding. A stylus surface profilometer was used to measure wear rate. The investigation of wear tracks and wear mechanism was performed using Scanning Electron Microscopy (SEM). The research results showed that coatings with different bilayer period performed different tribological behaviour. The proper tribological media applied in the wear tests could improve the wear properties of multilayer coatings. 相似文献
This paper reports on the structural, mechanical and tribological properties of molybdenum–copper nanocomposite films ‘doped’ with small amounts of nitrogen, which contain either no nitride phase (i.e. the nitrogen is held in interstitial solid solution, mainly in molybdenum) or small amounts of lower nitrides (i.e. Mo2N). All films were deposited on Si wafers, AISI M2 high speed steel and AISI 316 stainless steel by reactive sputtering using a hot-filament-enhanced dc unbalanced magnetron system. A systematic approach was adopted to investigate the evolution of metal/metal and ceramic/metal phase combinations with increasing nitrogen content (up to 40 at.% N) in the film. Coating composition and microstructure were determined by cross-sectional TEM, SEM and XPS. XRD was used to identify (where possible) metallic and metal-nitride phases. Mechanical properties such as hardness and elastic modulus were determined by low load Knoop and instrumented Vickers indentation measurements. Reciprocating sliding, micro-abrasion and impact tests were performed to assess tribological performance.
It was found that increasing the nitrogen gas flow rate from 0 to 15 sccm (and therefore nitrogen content in the film from 0 to 24 at.% N), refined significantly the coating microstructure from columnar to a dense and more equiaxed morphology, increasing the hardness whilst maintaining (almost constant) elastic modulus values, close to that of molybdenum metal. Further increases in the nitrogen gas flow rate resulted in films that appeared to contain significant fractions of the Mo2N ceramic phase. SEM and cross-sectional TEM analyses of the film deposited at a nitrogen flow rate of 20 sccm (containing 36 at.% N) demonstrated a microstructure consisting of 50–100 nm wide columns, which contain small regions of contrast in dark-field images, of the order of 3–5 nm wide. A maximum hardness of 32 GPa and the highest hardness/modulus ratio was however found in the (predominantly metallic) film deposited at a nitrogen gas flow rate of 15 sccm. This film also performed best in both micro-abrasion and impact wear tests; in contrast, the ‘ceramic’ film (deposited at 20 sccm nitrogen flow rate) performed better in reciprocating sliding wear. 相似文献
The performance of cemented carbide inserts coated with various PVD-films in milling Inconel 718 is evaluated by innovative analytical and experimental methods. Three PVD films with different micro and macro structures were applied. The coatings’ strength properties were detected by nanoindentations and by impact tests at various temperatures. These results were considered in FEM calculations of the material removal process to determine the mechanical and thermal loadings of the cutting wedge. Employing this innovative methodology, it is possible to capture proactively the effect of the cutting conditions on tool wear, thus reducing the effort dedicated in traditional sequential cutting experimentation. 相似文献
During the Physical Vapour Deposition of coatings, the orientation of cemented carbides insert surfaces to the plasma flux direction affects the occurring film thickness distribution on the rake and flank, which in turn might influence the wear propagation in cutting processes. In the present paper the cutting performance in milling of PVD coated cemented carbides inserts with variable film thickness on the rake and flank is introduced and with the aid of FEM-supported calculations explained. The investigation results revealed that a thicker film on the tool rake in comparison to the existing one on the flank and moreover a thick and uniformly deposited film in the cutting wedge region significantly enhances the cutting performance in milling. 相似文献