			Home About us Contact

Multilayer Coatings (multilayer + coating)

Distribution by Scientific Domains

Polymers and Materials Science	66%

Selected Abstracts

Characterizations of Magnetron Sputtered CrSiN/ZrN Multilayer Coatings,from Structure to Tribological Behaviors,

ADVANCED ENGINEERING MATERIALS, Issue 8 2009
Zhiguo Zhang
In this study, CrSiN/ZrN multilayer coatings were prepared by a reactive magnetron sputtering system. The evolution of their microstructure, mechanical, and tribological properties as a function of the multilayer modulation period was studied. The results showed that the multilayers had a good modulation structure. CrSiN and ZrN individual layer in the multilayers were "amorphous-like" and amorphous structure, respectively. [source]

Abrasive Wear of DLC/PVD Multilayer Coatings: AFM Studies

LUBRICATION SCIENCE, Issue 3 2004
C. Martini
Abstract The tribological behaviour of multilayered coatings deposited on plain carbon steel was investigated by microscale abrasion tests (MSATs). The multilayered coatings consisted of an outer diamond-like carbon (DLC) layer, a physical vapour deposition (PVD) nitride-based interlayer, and an inner electroless Ni-P layer. PVD TiN- and Ti(C,N)-coated samples with and without the DLC outer layer were studied in order to evaluate the influence of each layer on the tribological behaviour of the multilayer-coated system. The MSATs were carried out using a device based on ball-cratering geometry: a hard steel sphere was rotated against the coated specimen in the presence of an aqueous suspension of SiC particles. The wear coefficients of the multilayers were calculated from the diameter of the wear craters. The morphology of the wear scars produced by the MSATs was studied by atomic force microscopy (AFM). The wear damage was described by measuring the r.m.s. roughness (Sq) on the sides of the wear craters. Roughness values were related to the wear coefficients (kc) for the different multilayers on the basis of mathematical elaboration typical of the ,design of experiment' (DOE) statistical technique. The presence of the DLC outer layer reduced the roughness of the crater sides and significantly increased the wear resistance of the multilayer only in the case of the PVD TiN sublayer. [source]

Multifunctional FeCo/TiN Multilayer Thin Films with Combined Magnetic and Protective Properties,

ADVANCED ENGINEERING MATERIALS, Issue 12 2009
Christian Klever
Abstract Coatings with thicknesses ranging from a few nanometer up to several micrometer produced by physical vapor deposition (PVD) processes have been established in engineering technologies since the early 1980s. In particular, magnetron sputtered wear resistance coatings are industrially established and capable to enhance tool lifetimes significantly. However, in cases where optical inspection of a coating in use is not possible, an intrinsic sensor function of the film would be beneficial. Therefore, the development of wear resistant coatings with an integrated sensor functionality based on the insertion of a magnetoelastic ferromagnetic phase is suggested. In combination with appropriate read-out electronics such a film system would be ready for online monitoring of the coatings' actual state (e.g., strain, temperature, volume loss). This paper focuses on the development of wear resistance coatings which simultaneously supply beneficial mechanical properties as well as ferromagnetic properties optimized for online non-contact read-out applications. Multilayer coatings obtained through alternate stacking of magnetron sputtered TiN and FeCo layers with a nominal total thickness of 1000,nm were produced as a model system meeting the above conditions. The bilayer period was varied down to 2.6,nm while the individual layer thickness ratio tTiN/tFeCo was determined by the deposition rates and maintained constant at a value of about 3/1. The films were vacuum annealed ex situ in a static magnetic field subsequent to the deposition. The constitution of the as-deposited and annealed coatings as well as their mechanical (nanohardness, Young's modulus) and magnetic properties (magnetization hysteresis, frequency-dependent permeability) are described. Finally, the suitability of the coatings for the use in remote-interrogable wear sensor applications is briefly discussed. [source]

A method for the tribological testing of thin, hard coatings

LUBRICATION SCIENCE, Issue 2 2002
R. Michalczewski
Abstract A new method has been developed for tribological testing of thin, hard antiwear coatings, using a ball-on-disc tribosystem, under conditions of dry sliding. In this, an Al2O3 ball is pressed against a coated steel disc. Wear debris is removed from the contact zone by a stream of dry argon in this novel method. This improves the stability of the tribological properties and the repeatability of the test results. All test conditions are precisely defined, in particular: the type of motion, air relative humidity, ambient temperature, sliding speed, load, tribosystem spatial configuration, substrate material, substrate hardness and roughness, and coating thickness. The method developed has been used to test various physical vapour deposition coatings (deposited by the vacuum arc method), i. e., single-layer TiN, Ti(C,N), CrN, and Cr(C,N), and multilayer Cr(C,N)/CrN/Cr and Cr(C,N)/(CrN+Cr2N)/CrN/Cr. It is shown that CrN coatings exhibit the best antiwear properties, and Ti(C,N) the worst. Friction coefficients for CrN and Cr(C,N) coatings are much lower than for the more commonly used TiN. Multilayer coatings have better antiwear properties than single-layer ones. [source]

Suppression of Premature Fracture of Silicon under Three-Point Bending: Role of Nanoscale Localized Deformation of Metallic Multilayered Coating,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2009
Yuan-Ping Li
Brittle single crystal Si with and without Au/Cu multilayer coating was investigated via three-point bending test. Load-bearing capacity of the Si coated with the Au/Cu multilayer is improved evidently compared with the bare Si. Especially the nanoscale plastic deformation of the multilayer was observed to be effective in delaying instable crack propagation within the Si. That would shed significant light in toughening methods of brittle materials. [source]

Impeding corrosion of sintered NdFeB magnets with titanium nitride coating

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2010
A. Ali
Abstract Sintered NdFeB magnets have poor corrosion resistance that renders them susceptible to corrosion in industrial and marine environments. This paper evaluates the properties of cathodic arc physical vapour deposited (CAPVD) titanium nitride coating for corrosion protection of sintered NdFeB permanent magnets. The performance of titanium nitride coating has been compared to the electrodeposited nickel,copper,nickel multilayer coating. The rates of coatings degradation in simulated marine environment were estimated with electrochemical impedance spectroscopy (EIS). Cyclic polarization was carried out to assess the pitting potential. The surface chemistry and coating morphologies were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for qualitative phase analyses of coatings and the substrate. It was figured out that the charge transfer resistance of CAPVD titanium nitride coating increased with exposure time. The negative rate of Rp-degradation for titanium nitride coating compared to the nickel,copper,nickel multilayer for equivalent exposure time is a unique and valuable result. Polarization results showed that ,pits re-passivation' of titanium nitride coating could be responsible for the extended corrosion protection of the NdFeB substrate. The magnetic properties remained comparable for both types of coatings. [source]

Achiral and chiral separations using MEKC, polyelectrolyte multilayer coatings, and mixed mode separation techniques with molecular micelles

ELECTROPHORESIS, Issue 6 2010
Candace A. Luces
Abstract Mixed mode (MM) separation using a combination of MEKC and polyelectrolyte multilayer (PEM) coatings is herein reported for the separation of achiral and chiral analytes. Many analytes are difficult to separate by MEKC and PEM coatings alone. Therefore, the implementation of a MM separation provides several advantages for overcoming the limitations of these well-established methods. In this study, it was observed that achiral separations using MEKC and PEM coatings individually resulted in partial resolution of eight very similar aryl ketones when the molecular micelle (sodium poly(N -undecanoyl- L -glycinate)) concentration was varied from 0.25 to 1.00%,w/v and the bilayer number varied from 2 to 4. However, when MM separation was introduced, baseline resolution was achieved for all eight analytes. In the case of chiral separations, temazepam, aminoglutethimide, benzoin, benzoin methyl ether, and coumachlor were separated using the three separation techniques. For chiral separations, the chiral molecular micelle, sodium poly(N -undecanoyl- L -leucylvalinate), was employed at concentrations of 0.25,1.50%,w/v for both MEKC and PEM coatings. Overall, the results revealed partial separation with MEKC and PEM coatings individually. However, MM separation enabled baseline separation of each chiral mixture. The separation of achiral and chiral compounds from different compound classes demonstrates the versatility of this MM approach. [source]

Protein separations using polyelectrolyte multilayer coatings with molecular micelles in open tubular capillary electrochromatography

ELECTROPHORESIS, Issue 4 2008
Candace A. Luces
Abstract Novel polyelectrolyte multilayer (PEM) coatings for enhanced protein separations in open tubular CEC (OT-CEC) are reported. Use of four cationic polymers (poly- L -lysine, poly- L -ornithine, poly- L -lysine-serine, and poly- L -glutamic acid-lysine), and three anionic molecular micelles, sodium poly(N -undecanoyl- L -leucyl-alaninate) (poly- L -SULA), sodium poly(N -undecanoyl- L -leucyl-valinate) (poly- L -SULV), and sodium poly(undecylenic sulfate) (poly-SUS) were investigated in PEM coatings for protein separations. The simultaneous effects of cationic polymer concentration, number of bilayers, temperature, applied voltage, and pH of the BGE on the separation of four basic proteins (,-chymotrypsinogen A, lysozyme, ribonuclease A, and cytochrome c) were analyzed using a Box Behnken experimental design. The influence of NaCl on the run-to-run reproducibility was investigated for PEM coatings containing each cationic polymer. All coatings exhibited excellent reproducibilities with a %RSD of the EOF less than 1% in the presence of NaCl. Optimal conditions were dependent on both the cationic and anionic polymers used in the PEM coatings. Poly- L -glutamic acid-lysine produced the highest resolution and longest migration time. The use of molecular micelles to form PEM coatings resulted in better separations than single cationic coatings. Chiral poly- L -SULA and poly- L -SULV resulted in higher protein resolutions as compared to the achiral, poly-SUS. Furthermore, the use of poly- L -SULV reversed the elution order of lysozyme and cytochrome c when compared to poly- L -SULA and poly-SUS. [source]

Characterizations of Magnetron Sputtered CrSiN/ZrN Multilayer Coatings,from Structure to Tribological Behaviors,

Ablation Resistance of Different Coating Structures for C/ZrB2,SiC Composites Under Oxyacetylene Torch Flame

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2009
Houbu Li
C/ZrB2,SiC composites were fabricated by polymer infiltration and pyrolysis combined with slurry impregnation method. Three kinds of coating structures for these composites were applied in order to improve their ablation resistance: pure silicon carbide coatings, ZrB2,SiC mixture coatings, and ZrC,SiC alternating multilayer coatings. The ablation experiments were carried out on an oxyacetylene torch flame with a temperature of about 3000°C. The ZrC,SiC alternating multilayer showed the best ablation resistance. The linear erosion rate for ZrC,SiC alternating multilayer coatings is half of that for ZrB2,SiC mixture and pure SiC coatings. A model was put forward to account for such a result. [source]

Thermal Barrier Coatings Design with Increased Reflectivity and Lower Thermal Conductivity for High-Temperature Turbine Applications

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2006
Matthew J. Kelly
High reflectance thermal barrier coatings consisting of 7% Yittria-Stabilized Zirconia (7YSZ) and Al2O3 were deposited by co-evaporation using electron beam physical vapor deposition (EB-PVD). Multilayer 7YSZ and Al2O3 coatings with fixed layer spacing showed a 73% infrared reflectance maxima at 1.85 ,m wavelength. The variable 7YSZ and Al2O3 multilayer coatings showed an increase in reflection spectrum from 1 to 2.75 ,m. Preliminary results suggest that coating reflectance can be tailored to achieve increased reflectance over a desired wavelength range by controlling the thickness of the individual layers. In addition, microstructural enhancements were also used to produce low thermal conductive and high hemispherical reflective thermal barrier coatings (TBCs) in which the coating flux was periodically interrupted creating modulated strain fields within the TBC. TBC showed no macrostructural differences in the grain size or faceted surface morphology at low magnification as compared with standard TBC. The residual stress state was determined to be compressive in all of the TBC samples, and was found to decrease with increasing number of modulations. The average thermal conductivity was shown to decrease approximately 30% from 1.8 to 1.2 W/m-K for the 20-layer monolithic TBC after 2 h of testing at 1316°C. Monolithic modulated TBC also resulted in a 28% increase in the hemispherical reflectance, and increased with increasing total number of modulations. [source]

Bio-hybrid nanocomposite coatings from sonicated chitosan and nanoclay

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010
Jari Vartiainen
Abstract Nanocomposite films and coatings with improved properties were produced from ultrasonic dispersed chitosan and hydrophilic bentonite nanoclay. Bio-hybrid coatings were applied onto argon,plasma-activated LDPE coated paper. The intercalation of chitosan in the silicate layers was confirmed by the decrease of diffraction angles as the chitosan/nanoclay ratio increased. Nanocomposite films and multilayer coatings had improved barrier properties against oxygen, water vapor, grease, and UV-light transmission. Oxygen transmission was significantly reduced under all humidity conditions. In dry conditions, over 99% reduction and at 80% relative humidity almost 75% reduction in oxygen transmission rates was obtained. Hydrophilic chitosan was lacking the capability of preventing water vapor transmission, thus total barrier effect of nanoclay containing films was not more than 15% as compared with pure chitosan. Because to very thin coatings (,1 ,m), nanoclay containing chitosan did not have antimicrobial activity against test strains. All coating raw materials were "generally recognized as safe" (GRAS) and the calculated total migration was in all cases ,6 mg/dm2, thus the coatings met the requirements set by the packaging legislation. Processing of the developed bio-hybrid nanocomposite coated materials was safe as the amounts of released particles under rubbing conditions were comparable with the particle concentrations in a normal office environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]