Key Engineering Materials Vols. 373-374

Abstract: Three types of nano-multilayer coatings, CrSiN, CrAlN and CrMoN, with different Si, Al and Mo contents were deposited on M42 substrates using a closed field unbalanced magnetron sputter ion plating (CFUMSIP) technique. Systematic characterization on the chemical composition, microstructure, hardness and wear properties of these multilayer coatings has been investigated using GDOES, low angle XRD, SEM, TEM, nanoindentation and wear tests. Experimental results revealed that all these three types of Cr, XN ternary coatings (X=Al, Si and Mo) are nano-multilayer structured. The CrAlN multilayer coatings showed the highest hardness and oxidation resistance among these three multilayer coatings. The CrMoN multilayer coatings exhibited the lowest friction coefficient although no appreciable improvements in wear resistance were observed as compared with the optimized CrN coatings.

Abstract: CrN coatings were deposited on cemented carbide substrates by filtered cathodic vacuum arc technique (FCVA). The effect of different deposition parameters: nitrogen partial pressure, substrate-bias voltage and preheating of the substrate, on the structural and mechanical properties of the coating was investigated. X-ray diffraction analysis was used to determine the structure and composition of the coatings. The tribological behaviour and wear properties of the coatings against Si3N4 ball at different normal loads were studied under reciprocating sliding condition. The results showed that a smooth and dense CrN coating with good properties can be obtained provided a pure Cr interlayer was pre-deposited. The optimal deposition parameters were the nitrogen partial pressure of 0.1 Pa, substrate-bias voltage of -100 V. Preheating of the substrate was no good for improving the properties of the coating. The FCVA CrN coating showed high hardness and good wear resistance, which was probably attributed to its smooth surface and dense microstructure. The wear mechanism of the CrN coating was a combination of abrasion and oxidation. However, the coating flaked off at high normal load due to the deficient adhesion strength of the coating to the substrate.

Abstract: Diamond film was deposited on spherical molybdenum substrate by DC arc plasma CVD method. Diamond film morphology, purities and orientation evolution, obtained from atomic force microscopy, scanning electron microscopy, Raman spectroscopy, X ray diffraction respectively, has showed that grains on the growth surface are compact, continuous and uniform. Characteristic diamond (111), (220), (311) peaks were found and (111) facets were predominant. It revealed that diamond film was polycrystalline texture characteristic. There is a typical diamond Raman spectrum peaks at 1332.0 cm-1, and not graphite and amorphous carbon characteristic peak. High purity diamond film was deposited. When methane concentration was increased, diamond film has more local clusters and vacancy defects such as voids, graphite inclusion, and hydrogen cluster. Therefore, some important parameters such as methane concentration and substrate temperature should be optimized in depositing diamond film.

Abstract: The magnetic filed arrangement of unbalance magnetron sputtering can be changed employed to expand the plasma region and induce more ions to bombard the films for fabricating excellent quality films. In this paper, four targets closed-filed unbalance magnetron sputtering was introduced, the effect of the different magnetic field arrangement on the titanium oxide films properties was investigated. By changing the distance from target to vacuum center, the different unbalance state of the magnetic field was formed around the substrate. The titanium oxide films were synthesized at different unbalance state of the magnetic field. The microstructure of the titanium oxide films was studied by X-Ray Diffraction (XRD), and the residual stress measurement for the films was determined by grazing incidence XRD. The results revealed that the higher unbalance of the magnetic field around the substrate, the higher ion current of the substrate. Comparing with increasing the substrate bias voltage, the ion current increased 2~4 times through changing magnetic field arrangement to induce higher unbalance of the magnetic field. Ion/atom ratio increase was in favor of rutile phase formation for titanium oxide film. The unbalance state increase resulted in more higher compressive stress in the films.

Abstract: High quality Nd:YVO4 thin films were fabricated successfully by using a pulsed laser deposition technique. The properties of the samples were characterized by using X-ray diffraction, atomic force microscopy, and prism-coupling measurements. According to above discussion, we concluded the optimal preparation conditions for Nd:YVO4 films prepared on Si/SiO2 substrates.

Abstract: TiN/carbon multilayer coatings were deposited on M2 and GCr15 wafers by ion beam assistant magnetron spurting deposition (IBMSD). The hardness, elastic modulus, fracture toughness, adhesion strength and tribological properties were investigated. The results show that TiN coating by means of static recoil N+ doped interface preparation and Ar+ beam assistant magnetron spurting has 2 times adhesion strength, 5 times hardness of none-beam-assistant TiN coating. The wear rate of GCr15 wafer with TiN(2h)/Carbon(4h) multilayer coating is 0.36×10-15m3/Nm,1/5 of that of GC15 wafer without coating. The wear rate of M2 wafer with TiN(2h)/Carbon(4h) multilayer coating is 2.8×10-15m3/Nm, 1/8 of that of M2 wafer without coating. The friction coefficient of GCr15 wafter with TiN(2h)/Carbon(4h) multilayer coating is lower than 0.15, and that is 0.04 for M2 wafer. These results indicate that thickness ratio of TiN to carbon is important for the tribological properties of TiN/carbon coating, thick lubricant carbon/thin load-support TiN multilayer coating has better comprehensive tribological properties.

Abstract: A silicon interlayer was introduced between the DLC films and 202 stainless steel substrate using a medium frequency magnetron sputtering. The adhesion was evaluated by the scratch tests and wear tests together. Two main parameters in the deposition process of Si interlayers, i.e. the sputtering current and pulse bias voltage, were optimized respectively, and the action mechanisms were discussed as well. Moreover, a special treatment with the purpose of forming a complete graded intermixed Si-Fe interface was designed to improve the adhesion strength further. DLC films with good adhesion strength were deposited on 202 stainless steel substrates using a silicon interlayer.

Abstract: Reactive magnetron sputtering technique was used to gain titanium nitride (TiN) films on W18Cr4V high-speed steel and GCr15 bearing steel substrates at low temperature. The Surface chemical composition of the films was analyzed using energy dispersive X-ray spectroscopy (EDXS) and the surface morphology was examined using atomic force microscopy (AFM). Moreover, a series of experiments have been conducted to study the relationship between interfacial bonding strength and some major technological parameters, that is, substrate surface roughness, negative bias voltage, intermediate transition layer, substrate hardness, and ion etching before deposition. The experimental results have indicated that the TiN film with typical ratio of chemical metric can be deposited on substrates using reactive magnetron sputtering technique below 140°C. The AFM image has showed that the TiN film using magnetron sputtering technique was composed of densely distributed nano-grains with uniform structure. Its surface was flat and smooth. The indentation testing results have showed that the increase of surface roughness and substrate hardness improves the bonding strength of TiN / substrate significantly. Furthermore, the bonding strength of TiN / substrate can also be improved through the following methods: (1) choosing a proper intermediate transition layer; (2) adopting ion etching before deposition and (3) increasing negative bias voltage before deposition.

Abstract: Composite fluorocarbon/ZnO films were deposited by R.F. sputtering using polytetrafluoroethylene (PTFE) and Zn target on polyethylene terephthalate (PET) substrate. Argon was used as the working gas and oxygen as reacting gas. The obtained films were characterized by AFM, UV-visible spectrophotometer, XPS and static contact angle measurements. The composite films are islands-structure composed of nanometer particles. Surface of the islands is not flat. The static contact angle of water is larger than 90°, possessing excellent hydrophobicity. The composite films exhibit multi-enhanced ultraviolet absorption due to π-π-conjugated molecular structure, surface morphology and nano-sized ZnO absorbing effect.

Abstract: In this experiment UDP450 was used to prepare the CrAlTiN films with different Y contents deposited on Si(100) substrates. The thickness and structure of CrAlTiN films were characterized by scanning electron microscopy (SEM). The results show that the thickness of CrAlTiN films increases with the increasing of Y contents in Al targets. Meanwhile, the structures of these films are column structures with the least changes. XPS and EDS results indicate that Al contents in the films also increased with the increasing of Y contents in Al targets. Voltages of Al targets were changed with the variation of Y contents in Al targets when CrAlTiN layers were formed. The current of Al targets was a constant during producing CrAlTiN layer. The original voltages of Al targets during forming CrAlTiN layers increased greatly with the increase of Y contents in Al targets. The results show that the collision probability between the neutral particles and positive ions increased in the vacuum chamber. This indicates that the sputtering yield of Al targets is increased at a higher voltage. Consequently, the growing speed of CrAlTiN film and the sputtering yield of Al targets are all improved with the addition of Y element.