A new [Ti/TiAlN/TiAlCN](5) multilayer coatings were deposited onto polished substrate AISI H11 (DIN 1.2343) steel by an industrial magnetron sputtering device. The tribological performance of the coated system was investigated by a ball-on-disk tribometer against 100Cr6 steel and Al2O3 balls. The friction coefficients and specific wear rates were measured at various normal loads (2, 5, 8, and 10N) and sliding velocities (0.2, 0.4, and 0.8 m/s) in ambient air and dry conditions. The phase structure, composition, wear tracks morphologies, hardness, and film/substrate adhesion of the coatings were characterized by light-microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), 3D-surface analyzer, nanoindentation, and scratch tests. Results showed that the deposited coatings showed low wear rates in the scale of 10(-15) m(3)/N m, low friction coefficients against 100Cr6 and Al2O3 balls in the range of 0.25-0.37, and good hardness in the range of 17-20 GPa. Results also revealed that the friction coefficients and disc wear rates decrease and increase, respectively with the increase in normal load and sliding velocity for both coating/Al2O3 and coating/100Cr6 sliding system. Compared with the uncoated-H-11 substrate, the deposited coating exhibited superior tribological and mechanical properties. The dominant wear mechanism was abrasive wear for coating/Al2O3 pair, while for coating/100Cr6 pair, a combination of mild adhesive wear, severe adhesive wear, and abrasive wear (extensive plowing) were the dominant wear mechanisms at different applied normal loads. (C) 2014 Elsevier B.V. All rights reserved.

There are several manufacturing processes, in which the employment of solid lubricants is limited. In addition, ecological damage and higher production costs are further consequences of using such solid lubricants. This work aims at using the great potential of thin film technology to deposit adaptive, self-lubricating coatings as an alternative to conventional solid lubricants. Using magnetron sputtering process several titanium aluminum vanadium nitride coatings (TiAlVN) were developed in this study. These quaternary coatings possess the ability of forming lubricious oxides, known as Magnéli phases, at elevated temperatures, which significantly reduces the friction coefficient and surface wear.

The phenomenon of glass-to-mold sticking is a major problem for industrial glass forming processes. Ternary TiAlN coatings attracted considerable industrial interest because of their excellent tribological performance and high oxidation resistance at high temperatures. Recently, multicomponent CrAlSiN and TiAlSiN coatings have been developed in order to gain high hardness and good thermal stability at temperatures exceeding 800°C. In this study, CrAlSiN, TiAlSiN and AlTiN coatings were deposited on tungsten carbide substrates by using a cathodic-arc deposition system with lateral rotating arc cathodes. Titanium, chromium and AlSi (12at.% of Si) cathodes were used for the deposition of CrAlSiN and TiAlSiN coatings. All the deposited CrAlSiN, TiAlSiN and AlTiN coatings showed a B1-NaCl crystal structure. The deposited CrAlSiN and TiAlSiN coatings exhibited nanocrystalline structure and possessed hardness as high as 35–37GPa after annealing at 700°C in air. The wettability of the CrAlSiN, TiAlSiN and AlTiN coated tungsten carbides by molten glass at temperatures between 300°C and 700°C in controlled air under 1.6Pa was measured by using an improved sessile drop method. The CrAlSiN showed a low oxidation rate and a non-wetting characteristic superior to TiAlSiN and AlTiN coatings.

It has been established that hardness and density of diamond-like carbon (DLC) layers can be raised by increasing ion energy during deposition, decreasing H-content and by increasing sp3-fraction. To confirm differences in hydrogen content of hydrogen containing and hydrogen free DLC films deposited at different bias voltages, layers were etched in oxygen atmosphere in a capacitively coupled plasma device. By employing real-time ellipsometry measurements, the H-content of the hydrogen containing a-C:H layers were estimated by determining the optical constants n and k (n-real part and k-imaginary part of the refractive index). In addition, DLC layers were analyzed by X-ray photoelectron spectroscopy to estimate the ratio of sp²- and sp³-hybridization. The mechanical and tribological properties of the coatings were evaluated by means of nanoindentation and ball-on-disc-tests. Finally correlations between these properties, H-content and sp3/sp2-ratio were obtained in an effort to explain different tribological behaviors of DLC-layers.

The extension of tool life is a crucial goal for heat resistant forming tools. Therefore, the industry is interested to reduce the friction and wear for these tools. The employment of metals, polymeric composites, and ceramics as solid lubricants increases the production as well as maintenance costs. Thus, the thin film technology and especially new self-lubricating coatings will become increasingly important. Titanium aluminum vanadium nitride as a self-lubricating coating has a high potential to improve the tribological behavior of heat resisting tool surfaces and has good mechanical properties such as a high hardness (more than 40GPa). In this study, TiAlVN coatings were deposited on HS6-5-2C high speed steel substrates by using a magnetron sputtering system. After annealing at 650°C, a V2O5 (Magnéli phase) which adds self-lubricating qualities to the coatings could be detected in the TiAlVN layer. Due to the influence of adhesive and cohesive damage processes, resulting from the residual stress behavior in the layer close to the substrate area, it is critical to measure residual stresses in order to increase the wear resistance. In addition to the phase analyses, residual stress measurements were investigated by means of x-ray diffractometry as well. An experimental method, based on the traditional sin²ψ-method and utilizing a grazing-incidence diffraction geometry was used in order to enhance the irradiation volume of thin film samples. This resulted in a higher intensity for high-angle Bragg peaks than for the Bragg–Brentano geometry. Furthermore, the mechanical and tribological properties of the TiAlVN coatings were characterized at elevated temperatures. The required results were provided by a high temperature ball-on-disk device and a nanoindenter.

Metal cutting tools having wear resistant and chemically stable ceramic coatings are in many applications superior in performance to uncoated tools. Titanium boron carbon nitride (TiBCN) is a hard material particularly suitable as a protective coating for cutting tools due to its excellent properties, such as a high hardness and high wear and corrosion resistance, among other. TiBCN films were grown on Si (100) and high speed steel substrates by means of reactively pulsed DC magnetron sputtering technique. Two B4C- and two Ti-targets, to which a pulsed DC voltage of middle frequency was applied, were used for the deposition of TiBCN. A chromium layer was first deposited to obtain a better adhesion of TiBCN to the substrates. The mechanical properties of these coatings deposited under different N2 contents were investigated. The substrates were biased through a medium frequency power supply. The bias voltage value was -90?V for all coatings. The total film thickness was maintained at approximately 2?mu m. The hardness of the coatings increased with reduced nitrogen content, while the adhesion decreased from 40.8 to 24.2?N, and the wear rate increased from 0.154 to 0.744?X?10-16?m3/N.m, the latter probably caused by the low content of the self-lubricating amorphous matrix of our coatings. However, the sample deposited by a nitrogen gas flow of 60?sccm presented a wear rate of four orders of magnitude smaller than the uncoated sample. The deposition method presented in this work seems very promising for the manufacture of TiBCN coatings.

Hydrogenated amorphous carbon (a-C:H) films have extraordinary tribological properties under dry conditions since the C-atoms at the surface are hydratized and not available for any bonding with the opposing material. Under wet conditions water molecules are weakly absorbed by the a-C:H-coatings so the interaction between the coating surface and the tribological counterpart changes to a dipole-like interaction which is disadvantageous for the tribological performance. According to this, the hydrogen-content plays an important role in the wear and friction behavior of diamond-like carbon (DLC) coatings under different humid conditions.This work focuses on the quantification of the hydrogen content of differently bias a-C:H top layered coating systems and their influence on the tribological behavior under different humidity conditions. By means of a magnetron sputter device DLC-coating systems with an a-C:H-top layer have been deposited at bias voltages between -75 and -200 V. In order to quantify the hydrogen content of the layers Nuclear Reaction Resonance Analysis (NRRA) was used. In combination with the results of the tribological tests under different humid conditions using a ball-on-disk-tester, correlations between the hydrogen content, the bias voltage and the wear and friction performance were made. A clear relationship between the bias voltage and the hydrogen content has been observed, since the values decrease consistently from 27.2 at.% at -75 V to a minimum of 19.9 at.% at -200 V bias voltage. Furthermore the different humidity levels show a strong influence on the tribological performance, while the bias voltage effects mainly the wear and friction results of the samples tested under wet conditions. (C) 2011 Elsevier B.V. All rights reserved.

Abstract A hydrogen-free DLC (diamond-like carbon) coating was deposited with a bias voltage of 150 V on various high and low alloy tool steels to study the effect of the pre-treatment of the steel substrate on the wear behaviour of the DLC coating in sliding contact with uncoated counterparts. The morphology and mechanical properties of the DLC coating as well as the effect of plasma nitriding on the surface roughness and the hardness of the steels were studied in order to perform a correlation with the results of tribology tests. It could be concluded from the results that the plasma nitriding of the high alloy tool steel X210CrW12 leads to a significant decrease in the wear and friction coefficient of the DLC coating. Furthermore, it was found that plasma nitriding of the steel results in a decrease in the wear of uncoated counterparts as well. Finally, the wear mechanisms and failure of DLC coatings deposited on various steels were compared with each other and discussed analytically.

Hard and wear resistant thin layers provides significant improvements in tools employed in manufacturing industry and are recently of great interest to increase as well as to enhance the tools' performance and lifetime. Ceramic PVD-layers already feature a high hardness combined with a high abrasive wear resistance. However, such layers possess only a limited lifetime due to their low toughness. To increase the toughness as well as the durability of such layers multilayer systems are steadily developed. This research work presents the first results of the influence of the steel substrate pretreatments, multilayer designs and coating process parameters on the properties of two innovative PVD metal-ceramic multilayers, Ti/TiAIN and Cr/CrAlN. It was obviously that the substrate pretreatment and the multilayer design have a large influence on the layer properties and residual stresses.

Since diamond like carbon layers feature excellent mechanical and tribological behavior under defined environmental circumstances, they are well established in a wide field of industrial and automotive applications in the last decade. However, the pretreatment of the substrate plays also an important role in supporting and enforcing the excellent properties of the coatings. This work analyses the effect of the plasma nitrided cold working steel substrate (80CrV2) on the adhesion, friction and wear resistance of DLC-coatings and compares it to the performance of DLC-coatings applied on a non-hardened substrate material. Therefore the grinded and polished specimens were nitrogen-hardened in an Arc-PVD (Physical Vapor Deposition)-device before the DLC-coating was applied in a Magnetron Sputter-PVD-process. In order to measure the hardness of the thin film coating, a nanoindenter was used. The adhesion was tested with a scratch tester and the wear resistance was measured by using a Ball-on-disc-tester. A 3D-profilometer and a SEM (Scanning Electron Microscope) were utilized to analyze the scratches and wear tracks on the samples. With these results correlations between the substrate nitriding and the mechanical and tribological performance of the DLC-coating were made.

Für die verarbeitende Industrie werden zunehmend harte und verschleißfeste Beschichtungen mit hoher Lebensdauer entwickelt. Keramische PVD‐Schichten besitzen bereits eine hohe Härte und Verschleißfestigkeit. Allerdings weisen derartige Schichten eine begrenzte Lebensdauer durch eine niedrige Duktilität auf. Zur Erhöhung ihrer Lebensdauer beim industriellen Einsatz werden zunehmend Multilayer weiterentwickelt. Dieser Beitrag stellt die ersten Untersuchungsergebnisse zum Einfluss der Substratvorbehandlung, des Schichtdesigns und der Prozessparameter von mehrlagigen metall‐keramischen PVD‐Schichten auf die Eigenschaften eines innovativen Gesamtverbundes, Ti/TiAlN und Cr/CrAlN auf Stahl vor. Sie belegen, dass die Vorbehandlung des Substrats und das Schichtdesign einen deutlichen Einfluss auf die Schichtmerkmale und den Eigenspannungszustand ausüben.

Excellent wear and friction properties are important factors in almost all branches of industry. They increase the tool life just as affecting the power consumption, the surface finish of the workpiece and the production rate in a positive way. To facilitate higher productivity at lower operating cost, it is of particular importance to use tools with enhanced wear and friction attributes. Novel amorphous diamond-like-carbon (DLC) coated tools provide these properties in dry and even in humid environment which offers application possibilities in the wood machining industry.The forestry, timber-, and paper-industry in Europe have a production value of approximately 400 billion Euros per year. For this reason, the supplying industry is very conscious to develop highly efficient tools. Especially wear and high friction of cutting tools are limiting factors in the processing of bulk wood.This work is focused on the development of a DLC-system with high wear and friction resistance also under humid conditions which especially exist during the processing of bulk wood. Using the Physical Vapor Deposition (PVD)-process different DLC-coating systems have been deposited, in which the layer properties have been designed related to the humidity conditions. The layer properties and coating parameters have been systematically analyzed with special emphasis on tribological attributes. Tungsten carbide counterparts were used during wear and friction tests to analyse the tribological behaviour of the coatings. Furthermore Raman spectroscopy was applied to characterize the layers microstructure. Correlations between layer structure and corresponding wear and friction properties have been scrutinized. (C) 2009 Elsevier B.V. All rights reserved.

Due to the high forming velocities during electromagnetic sheet metal forming processes, a high impact force acts between workpiece and die. Here, the die surface sustains high damages shown by high wear and galling of the workpiece on the die surface. To enhance the die lifetime, a novel coating concept based on the PVD (physical vapour deposition) process was developed. In doing so, the hardness and the toughness of the designed layers were varied and adjusted to the demands of AlMg-sheet forming process.

Even though amorphous diamond-like carbon (DLC) coated tools with their low friction and high wear resistance are well established in a wide field of industrial applications, their employment into humid environments is limited. In humid environments hydrogenated DLC-layers show high friction coefficients and low wear resistance.This work is focused on the development of DLC-coating systems with high wear resistance and low frictional coefficients in the humid environment. Using the Physical Vapor Deposition (PVD)-process, different DLC-coating systems have been deposited, in which the layer properties have been designed related to the humidity conditions. Coating parameters, layer microstructure and layer properties have been systematically analyzed with special emphasis on tribological properties. Correlations between layer structure and corresponding wear as well as friction properties have been scrutinized. The results showed that the coatings with a hydrogen-free top layer have the highest wear resistance and best frictional behavior under humid conditions compared to hydrogenated a-C:H-layers. (C) 2007 Elsevier B.V. All rights reserved.

Two different kinds of Time Temperature Transformation (TTT) diagrams are known. The first one are Isothermal Transformation (IT) diagrams and the second one Continuous Cooling Transformation (CCT) diagrams. These diagrams are important for the correct heat treatment of aluminium alloys, because they provide information about the required quenching rate, which is necessary to obtain a supersaturated solid solution during age hardening. Furthermore, it is possible to determine the lowest quenching rate, which permits both a high strength and a small distortion of the component after age hardening. In the literature IT diagrams for different aluminium alloys are available. To determine these diagrams, a solution annealing followed by quenching to defined temperatures is necessary. At these temperatures the alloy is kept isothermally until a transformation has started. These diagrams are not directly portable on continuous cooling, because of the different cooling paths.