Hybrid Physical Vapor Deposition Research Articles

Tribological behavior of duplex CrN/DLC and nano-multilayer DLC-W coatings on valve tappet under elevated temperature and varying load

In this work, the effect of increasing contact load and elevated temperature on the friction and wear rate of duplex CrN/DLC and nano-multilayer DLC-W deposited by hybrid Physical Vapor Deposition and Plasma Enhanced Chemical Vapor Deposition (PVD-PECVD) on valve tappet. The tribological behavior of the coatings were studied through reciprocating dry sliding experiments at temperatures between 25 and 250 °C, with 10 N step-increment from 5 to 50 N. The results presented revealed that the coefficient of friction of the duplex CrN/DLC coating was lowest at 150 °C and 20 N, while the nano-multilayer DLC-W coating was lowest at 25 °C and 50 N. The wear rate of the duplex CrN/DLC coating and the nano-multilayer DLC-W coating were the lowest at 25 °C. The wear rates for both coatings continued to increase with increasing temperature.

(AlCrNbSiTi)N/TiN multilayer films designed by a hybrid coating system combining high-power impulse magnetron sputtering and cathode arc deposition

We designed a hybrid physical vapor deposition coating system equipped with high-power impulse magnetron sputtering (HiPIMS) and cathode arc deposition (CAD) systems. With this technique, we fabricated (AlCrNbSiTi)N/TiN multilayer films consisting of alternating layers of (AlCrNbSiTi)N, a high-entropy alloy nitride (HEAN) with enhanced thermal stability, and TiN, a material known for its high hardness. For this hybrid coating system, a new nucleation and growth model was proposed to explain the thin film deposition phenomenon. Film growth occurred through a self-induced repeated nucleation mechanism. The effects of the modulation period on the microstructural, mechanical, and oxidation resistance properties of the coatings were investigated using scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and nanoindentation. All coatings exhibited a B1-NaCl-type face-centered cubic crystal structure. High-resolution TEM imaging revealed misfit dislocations between the HEAN and TiN layers and low-angle boundary dislocations between the subgrains. The 64-layer coating displayed outstanding mechanical, oxidation resistance, and tribological properties compared with those of previously reported multilayer coatings. The plastic deformation index, H3/E2, of the mono- and multilayer coatings increased from 0.17 to 0.37 GPa. After oxidation at 800 °C for 2 h in an ambient atmosphere, the thickness of the oxidation layer decreased from 1228 to 85 nm. Furthermore, the maximum flank wear of a coated tool after the milling test was less than that of the uncoated tool (201 vs. 528 μm), suggesting a large improvement in lifetime.

Effect of C2H2 flow rate and a Ti/TiN/TiCN interlayer on the structure, mechanical and tribological properties of a-C:H films deposited using a hybrid PVD/PECVD process with an anode-layer ion source

Diamond-like carbon (DLC) films were deposited onto 316L stainless steel using the hybrid physical vapor deposition (PVD)/plasma-enhanced chemical vapor deposition (PECVD) process with an auxiliary anode-layer ion source at C2H2 flow rates of 40–100 sccm to enhance mechanical and tribological properties of a-C:H films. The films were characterized using transmission electron microscope (TEM), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation and ball-on-disk rubbing tribometry. The hardness, tribological properties and interfacial bonding were significantly improved in the presence of the Ti/TiN/TiCN interlayer deposited by high-power impulse magnetron sputtering (HiPIMS). Results showed that a-C:H films were uniform and dense, the sp3 C content increased with an increase in the C2H2 flow rate from 40 to 80 sccm, and decreased when it was further increased to 100 sccm. The a-C:H film with the interlayer prepared at 80 sccm C2H2 exhibited the highest hardness (27.2 ± 0.5 GPa), H/E (0.137), and H3/E2 (0.510). Moreover, friction-wear tests demonstrated that the incorporation of the Ti/TiN/TiCN layer increased the wear resistance of the a-C:H film, achieving the lowest coefficient of friction (CoF, 0.148), wear rate (1.08 × 10−9 mm3 N−1 mm−1) and width of the wear track (177 μm) at 80 sccm C2H2.

Comparative Analysis over Tribology Characterization of TiAlN and TiAlSiN PVD Coating on Plasma Nitride Alloy 20

The nickel–iron–chromium (alloy 20) is enriching by hybrid surface treatment through plasma nitride (PN) and physical vapor deposition (PVD) process. The plasma nitriding process takes 12 h at 500 °C. Potentiodynamic testing is used to characterize the corrosion performance of the treated material, followed by morphological analysis of the exposed surface; XRD, EDX, SEM, hardness, and tensile testing are used to investigate appropriate coating properties. Plasma nitride and hybrid PVD nickel–iron–chromium alloys exhibit perlite (γ + α′) phases and martensite (γ + α) phases, respectively. The martensite microstructure ensures superior tensile strength and hardness. The pin-on-disc tribometer test proposes to analyze friction and hard-faced behavior in the dry sliding position. The inclusion of Si improves the adherent oxide film, resulting in a low wear rate in TiAlSiN alloy 20. Due to the presence of the passive film, TiAlSiN alloy 20 exposes the most passive region to attain better corrosion resistance.Graphical Abstract

Effect of nitriding pre‐treatment on the tribocorrosion behavior of physical vapor deposition‐coated tool steel

AbstractCr‐Al‐Ti‐B‐N hard coating is deposited onto the AISI D2 cold‐worked tool steel by means of a hybrid physical vapor deposition (PVD) technique. The effect of plasma nitriding pre‐treatment on the tribocorrosion behavior of the hard‐coated tool steel is investigated using a ball‐on‐disc sliding wear tribometer equipped with an electrochemical testing set up. Tribocorrosive characteristics are analyzed by optical and scanning electron microscopy, 3D surface profilometry, and open circuit potential (OCP) measurement. The coefficient of friction and OCP varies depending on the degree of damage to the hard coating, such that the point at which the substrate is first exposed can be identified by these measurements. The plasma nitriding pretreatment increases the surface hardness significantly and, therefore, the adhesion of the PVD hard coating to the substrate material. As a consequence, the material's wear resistance is enhanced and its durability against tribocorrosion is improved.

Structure, wear and corrosion behaviours of Cr–Al–C and multilayer [Cr–Al–C/a-C]n coatings fabricated by physical vapour deposition and plasma-assisted chemical vapour deposition techniques

The structures, wear resistances, and corrosion behaviours of Cr–Al–C and multilayer [Cr–Al–C/a-C]n coatings, fabricated by physical vapour deposition (PVD), plasma-assisted chemical vapour deposition (PACVD), or their combination, were studied. A CrAl target served as a source of chromium and aluminium, while a graphite target or acetylene served as sources of carbon. Depending on the type of carbon source, Cr–Al–C or Cr–Al–C(H) coatings were obtained. Multilayer [Cr–Al–C/a-C]20 and [Cr–Al–C(H)/a-C:H]20 coatings were fabricated by alternating pair layers of [Cr–Al–C (PVD)/a-C (PVD)] and [Cr–Al–C(H) (PVD–PACVD)/a-C:H (PACVD)], respectively. a-C and a-C:H are hydrogen-free and hydrogenated diamond-like carbons. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy were employed to investigate the coating structures. Along with the amorphous matrix, chromium carbide, and CrxAl1-xC nanograins, clusters of nanocrystalline graphite as spherical inclusions and plates, probably of several graphene layers, were observed in Cr–Al–C. This structure provided high hardness and corrosion resistance. Along with the amorphous matrix, Cr2AlC and chromium carbide nanoclusters and clusters of nanoscale CVD diamond with wide boundaries of sp2-bonded carbon were observed in Cr–Al–C(H), whose hardness did not exceed 8.9 GPa. The multilayer structures significantly increased the wear resistances. The specific coefficient of wear rate (SCWR) of [Cr–Al–C/a-C]20 was five times lower than that of Cr–Al–C. Hybrid PVD–PACVD technology provided favourable conditions for the formation of wear-resistant coatings. The SCWR of [Cr–Al–C(H)/a-C:H]20 was 47 times lower than that of [Cr–Al–C/a-C]20. The high wear resistance of the multilayer coatings was associated with the structure, low friction coefficient, high crack resistance, and strengthened interface boundaries.

DLC and DLC-WS2 Coatings for Machining of Aluminium Alloys

Machine-tool life is one limiting factor affecting productivity. The requirement for wear-resistant materials for cutting tools to increase their longevity is therefore critical. Titanium diboride (TiB2) coated cutting tools have been successfully employed for machining of AlSi alloys widely used in the automotive industry. This paper presents a methodological approach to improving the self-lubricating properties within the cutting zone of a tungsten carbide milling insert precoated with TiB2, thereby increasing the operational life of the tool. A unique hybrid Physical Vapor Deposition (PVD) system was used in this study, allowing diamond-like carbon (DLC) to be deposited by filtered cathodic vacuum arc (FCVA) while PVD magnetron sputtering was employed to deposit WS2. A series of ~100-nm monolayer DLC coatings were prepared at a negative bias voltage ranging between −50 and −200 V, along with multilayered DLC-WS2 coatings (total thickness ~500 nm) with varying number of layers (two to 24 in total). The wear rate of the coated milling inserts was investigated by measuring the flank wear during face milling of an Al-10Si. It was ascertained that employing monolayer DLC coating reduced the coated tool wear rate by ~85% compared to a TiB2 benchmark. Combining DLC with WS2 as a multilayered coating further improved tool life. The best tribological properties were found for a two-layer DLC-WS2 coating which decreased wear rate by ~75% compared to TiB2, with a measured coefficient of friction of 0.05.

Tribological studies on self-lubricating (Cr,Al)N+Mo:S coatings at elevated temperature

Due to the high material utilization and the associated resource and energy efficiency, production processes from the field of cold forging of steel are of great importance. At present, environmentally harmful lubricants have to be used to ensure process stability as well as low wear and friction. Due to environmental, economic and legislative aspects, there is an increased research potential to reduce or to completely substitute lubricants. To achieve the goal of lubricant free dry cold forging of steel, physical vapor deposition (PVD) coatings with self-lubricating properties are applied on forming tools. Promising for this application are PVD coatings on the basis of a (Cr,Al)N hard phase with embedded molybdenum and sulfur which simultaneously meet the requirements of high wear resistance and friction reduction. In the presented work, three self-lubricating coatings (Cr,Al)N+Mo:S deposited with varying bias voltage were investigated. The hybrid PVD technology, consisting of direct current and high power pulse magnetron sputtering dcMS/HPPMS, was used for the coating deposition in an industrial coating unit. Two different steels AISI D2 (DIN 1.2379) and AISI M2 (DIN 1.3343) were used as substrate materials. The influences of substrate material and heat treatments at T=250°C were investigated. The samples were analyzed with respect to the universal hardness HU and modulus of indentation EIT using nanoindentation. To determine the interfacial adhesion of the compound coating/substrate, Rockwell indentation and scratch tests were carried out. For the analysis of the tribological behavior, unhardened AISI 5115 (DIN 1.7131) was used as counterpart material. The influence of the elevated temperature on the friction and wear behavior was investigated by Pin-on Disk (PoD) at T=250°C and T=23°C. The wear of the basic bodies as well as the counterparts were analyzed by confocal laserscanning microscopy. The investigations have shown that the high temperature has a significant influence on the friction and wear behavior. The wear rate of the counterparts decreases by up to a factor greater than x=100 compared to the test at T=23°C. Furthermore, the wear rates of the basic body of the uncoated reference specimen increase rapidly at tribological stress at high temperatures. The examined coatings exhibit high wear resistance at elevated temperatures. The contact surface was studied by Raman spectroscopy after the tribological tests. PoD tests have shown, that the applied coatings led to a significantly reduction in friction most likely due to the tribo-chemically induced formation of self-lubricating MoS2 reaction layers.

Effect of Surface Wear on Corrosion Protection of Steel by CrN Coatings Sealed with Atomic Layer Deposition.

Corrosion protection of steel obtained with physical vapor deposition (PVD) coatings can be further improved by sealing the intrinsic pinholes with atomic layer deposition (ALD) coatings. In this work, the effect of surface wear on corrosion protection obtained by a hybrid PVD CrN/ALD Al2O3/TiO2 nanolaminate coating was studied. The samples were investigated by alternating surface wear steps and exposure to salt solution and consecutively the progression of corrosion after each wear and each corrosion step was evaluated. Optical microscopy, scanning electron microscopy (SEM), and energy-dispersive spectroscopy showed that the rust spots were almost exclusively located on positions at which the wear steps had removed the top surface of the PVD CrN coating. Nevertheless, even after complete removal of the ALD nanolaminate from the top of the CrN surface by sandpaper grinding, the corrosion current density was less than half compared to the PVD CrN coating alone without surface wear. Cross-sectional SEM images obtained with focused ion beam milling showed not only the presence of the ALD coating at the CrN defects but also the opening of new pathways for the corrosion to attack the substrate. A mechanism for the effect of wear on the structure and corrosion protection of hybrid PVD/ALD coatings is proposed on the basis of this investigation.

Triboactive CrAlN+X hybrid dcMS/HPPMS PVD nitride hard coatings for friction and wear reduction on components

Increasing environmental awareness and energy costs are major driving forces behind the development of energy efficient machines. Simultaneously, increased energy efficiency often leads to higher power densities. Besides diamond-like carbon (DLC) coatings, nitride hard coatings deposited by physical vapor deposition (PVD) show a high potential for wear reduction on machine components. However, regarding friction reduction in lubricated tribological contacts, nitride hard coatings still exhibit a high demand for research since state-of-the art lubricants are tailored to interact with steel surfaces in order to form friction reducing tribolayers. Therefore, the addition of triboactive elements (X) into nitride hard coatings is a promising approach to enhance tribological interactions with lubricants and to reduce friction. The aim of the paper is the analysis of the tribological interaction between the nitride hard coating (Cr,Al)N+X and lubricants. Therefore, a mineral oil based reference and a mineral oil doped with a sulphur additive were investigated regarding interactions with the coatings under tribological conditions. The coatings were deposited in a low temperature T≤200°C hybrid PVD coating process on case hardened steel AISI5115 (16MnCr5E). The coating and compound properties were investigated. The tribological behavior of the coatings was tested in a pin on disc (PoD) tribometer against inert ceramic Si3N4 counter bodies. The tests were conducted at temperatures T=90°C and T=130°C at Hertzian contact pressures p0≈1,600MPa and p0≈1,900MPa. Under the given tribological conditions a friction reduction was achieved by adding the triboactive element Mo into the coatings. Raman spectroscopy revealed that MoS2 was formed in-situ during the tribological tests. The investigated (Cr,Al)N+Mo coatings are therefore a promising approach for friction reduction in highly loaded tribological systems.

Hybrid Physical Chemical Vapor Deposition of Magnesium Diboride Inside 3.9 GHz Mock Cavities

Magnesium diboride (MgB 2 ) is considered a candidate for the next generation superconducting radio frequency (SRF) cavities due to its higher critical temperature T c (40 K) and increased superheating field (H sh ) compared to other conventional superconductors. These properties can lead to reduced BCS surface resistance (R BCS S ) and residual resistance (R res ), according to theoretical studies, and enhanced accelerating field (E acc ) values. We have investigated the possibility of coating the inner surface of a 3.9 GHz SRF cavity with MgB 2 by using a hybrid physical-vapor deposition (HPCVD) system designed for this purpose. To simulate the actual 3.9 GHz SRF cavity, we employed a stainless steel mock cavity for the study. The film qualities were characterized on small substrates that were placed at the selected positions within the cavity. MgB 2 films on stainless steel foils, niobium pieces, and SiC substrates showed transition temperatures in the range of 30-38 K with a c-axis-oriented crystallinity observed for films grown on SiC substrates. Dielectric resonator measurements at 18 GHz resulted in a quality factor of over 30 000 for the MgB 2 film grown on a SiC substrate. By employing the HPCVD technique, a uniform film was achieved across the cavity interior, demonstrating the feasibility of HPCVD for MgB 2 coatings for SRF cavities.

Ti-doped hydrogenated diamond like carbon coating deposited by hybrid physical vapor deposition and plasma enhanced chemical vapor deposition

Diamond-like carbon films containing titanium and hydrogen (Ti-doped DLC:H) were synthesized using a hybrid technique based on physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD). The film was deposited under a mixture of argon (Ar) and acetylene gas (C2H2). The amount of Ti in the Ti-doped DLC:H film was controlled by varying the DC power of the Ti sputtering target ranging from 0 to 240 W. The composition, microstructure, mechanical and chemical properties of Ti-doped DLC:H films with varying Ti concentrations, were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nano indentation, a ball-on-disk tribometer, a four-point probe system and dynamic anodic testing. As a result, the optimum composition of Ti in Ti-doped DLC:H film using our hybrid method was found to be a Ti content of 18 at. %, having superior electrical conductivity and high corrosion resistance, suitable for bipolar plates. Its hardness value was measured to be 25.6 GPa with a low friction factor.

Cr-Si-Al-N 코팅의 상형성 및 표면 물성에 미치는 Si 함량의 영향

Cr-Si-Al-N coating with different Si content were deposited by hybrid physical vapor deposition (PVD) method consisting of unbalanced magnetron (UBM) sputtering and arc ion plating (AIP). The deposition temperature was <TEX>$300^{\circ}C$</TEX>, and the gas ratio of <TEX>$Ar/N_2$</TEX> were 9:1. The CrSi alloy and aluminum targets used for arc ion plating and sputtering process, respectively. Si content of the CrSi alloy targets were varied with 1 at%, 5 at%, and 10 at%. The phase analysis, composition and microstructural analysis performed using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) including energy dispersive spectroscopy (EDS), respectively. All of the coatings grown with textured CrN phase (200) plane. The thickness of the Cr-Si-Al-N films were measured about <TEX>$2{\mu}m$</TEX>. The friction coefficient and removal rate of films were measured by a ball-on-disk test under 20N load. The friction coefficient of all samples were 0.6 ~ 0.8. Among all of the samples, the removal rate of CrSiAlN (10 at% Si) film shows the lowest values, <TEX>$4.827{\times}10^{-12}mm^3/Nm$</TEX>. As increasing of Si contents of the CrSiAlN coatings, the hardness and elastic modulus of CrSiAlN coatings were increased. The morphology and composition of wear track of the films was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy, respectively. The surface energy of the films were obtained by measuring of contact angle of water drop. Among all of the samples, the CrSiAlN (10 at% Si) films shows the highest value of the surface energy, 41 N/m.

Deposition and characterization of TiAlSiN coatings prepared by hybrid PVD coating system

TiAlSiN coatings with different Si contents were deposited on silicon and high-temperature alloy by using a hybrid physical vapor deposition coating system, where the cathodic arc ion plating was combined with a twin target mid-frequency magnetron sputtering. The chemical composition, microstructure, cross-sectional structure and morphology were carried out by X-ray photoelectron spectroscope (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM), respectively. NanoTest 600 nanomechanical system and ball-on-disc friction tester were used to investigate the mechanical and friction properties of TiAlSiN coatings. The worn surface of the TiAlSiN coatings and counterballs were investigated by means of surface profilometer and optical microscope. The wear rates were also measured by surface profilometer. The results showed that the Si addition did not change the coatings growth orientation, and the coating transfered into amorphous phase when the Si content reached about 13.9 at.%. The tribological properties and the hardness were improved by solid solution of Si atoms and grain boundary strengthening of SiNx amorphous phase with moderate Si content addition. In addition, the SiNx amorphous phase improved oxidation resistance of TiAlN coating, but with a high Si content (more than 8.3 at.% in this work) the agglomeration of SiNx amorphous phase would reduce the mechanical properties and oxidation resistance of the coating. Copyright © 2014 John Wiley & Sons, Ltd.

Microstructure and phase forming behaviour of chrome based multi-composition nitride coatings with nanolayer structures

Nanoscale multilayer Cr–Nb–N hard coatings were fabricated by reactive hybrid physical vapour deposition (PVD), which was combined with arc ion plating (AIP) for depositing chromium (Cr) and an unbalanced magnetron (UBM) DC sputter for depositing niobium (Nb) on a steel substrate under a controlled gas mixture of Ar and N2. The phase evolution and microstructure of the coatings were analysed by X-ray diffractometer (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The formation behaviour of the multilayer structure of the coatings was changed using different rotation conditions for the substrate. The Cr–Nb–N coatings, which formed at a substrate rotation of 5 or 6rpm, exhibited modulation of the peaks approximately 36°, (111) plane, which indicated the formation of a superlattice in the XRD results. The superlattice structured Cr–Nb–N coating formed under the 5rpm rotation condition exhibits a large layer period (~25nm) and improved hardness (~35GPa) compared to other multilayer Cr–Nb–N or monolithic CrN coatings.

Effect of interlayers on the structure and properties of TiAlN based coatings on WC-Co cemented carbide substrate

Two interlayers (Ti and Cr) have been evaluated with respect to their influence on the structure and growth of TiAlN based coatings on WC-Co cemented carbide by a non-commercial hybrid PVD (physical vapor deposition) coater by Sichuan University in China. The structure and the growth morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The diffusion of interlayer was tested by Energy Diffraction Spectrum (EDS). Nanoindentation techniques and Rockwell HRC indentations were carried out to investigate the mechanical properties. The results show that the structure and the growth style change in the coatings on Cr interlayer, and this can be explained by thermodynamic theories. Cr interlayer exhibits a better diffusion compared with Ti interlayer, partly resulting in the transition from columnar crystal to equiaxed crystal. Columnar crystals disappear with the addition of Si, too. Due to the diffusion of Cr interlayer and the growth style changes in the coating, a transition zone is formed, and it is estimated to improve the adhesion. Good adhesion occurs in the coating with Cr interlayer. The hardness of TiAlN on Cr interlayer increases, and the Ti/(Ti,Si,Al)N coating shows the hardness as high as 40.0Gpa.

Simple method of hybrid PVD/PECVD to prepare well-dispersed cobalt–plasma polymerized hexamethyldisilazane nanocomposites

A simple and easy method to prepare well-dispersed cobalt–plasma polymerized hexamethyldisilazane (Co–pp HMDSN) nanocomposites is presented. A hybrid physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD) technique was used to prepare finely dispersed Co–pp HMDSN nanocomposites. The metal filling factor could be varied from 4% to 34%. Structural investigations were performed using transmission electron microscopy (TEM) and X-ray diffractometry (XRD). They revealed the presence of amorphous cobalt nanoparticles of size ~2–3nm at lower filling factor, whereas crystalline CoO nanoparticles of size ~6nm were observed at higher filling factor. Energy dispersive X-ray spectroscopy (EDX) and profilometry were employed to determine the filling factor. Compositional analysis using Fourier transform infrared (FTIR) spectroscopy indicated the presence of SiO and SiC bonds in the polymer matrix. The influence of oxygen was observed in all nanocomposites. With the increase in filling factor the polymer matrix was significantly modified. A set of well-dispersed Co–pp HMDSN nanocomposites with varying metal filling factors was prepared which is suitable as precursor for calcination. As the functional properties of the calcinated nanocomposites are dependent on the properties of the precursors, the importance of a detailed study of the precursors for calcination is emphasized. A simple and generalized procedure to introduce well-dispersed metal nanoparticles into a polymer matrix is demonstrated.

중간층 조건에 따른 Cr-Mo-N 막의 상형성 및 마찰마모 거동 연구

Phase evolution and tribological behavior of Cr-Mo-N multi compositional films with different interlayer were investigated. The films were deposited by hybrid PVD (Physical Vapor Deposition) system consisted of dc unbalanced magnetron (UBM) sputtering and arc ion plating (AIP) sources. A pure molybdenum (Mo) was used as sputtering target and also a pure Cr was used as AIP target to form the Cr-Mo-N films. Various growth planes were found, no textured surface, in all of the multi composition films. Maximum value of microhardness was measured in Cr-Mo-N film with Mo interlayer as 29 GPa. Composition film was mainly showed the aspect of the adhesive wear than CrN film. The friction coefficient was decreased from 0.6 for pure CrN coating to 0.35 for Cr-Mo-N film with Mo interlayer. This result may come from the formation of metal oxide tribo-layer which is known as solid lubricant during the wear test.

Hybrid PVD로 제조된 Ti-Me-N (Me=V, Si 및 Nb) 나노 박막의 미세구조와 마모특성

Ti based nanocomposite films including V, Si and Nb (Ti-Me-N, Me=V, Si and Nb) were fabricated by hybrid physical vapor deposition (PVD) method consisting of unbalanced magnetron (UBM) sputtering and arc ion plating (AIP). The pure Ti target was used for arc ion plating and other metal targets (V, Si and Nb) were used for sputtering process at a gas mixture of Ar/<TEX>$N_2$</TEX> atmosphere. Mostly all of the films were grown with textured TiN (111) plane except the Si doped Ti-Si-N film which has strong (200) peak. The microhardness of each film was measured using the nanoindentation method. The minimum value of removal rate (<TEX>$0.5{\times}10^{-15}\;m^2/N$</TEX>) was found at Nb doped Ti-Nb-N film which was composed of Ti-N and Nb-N nanoparticles with small amount of amorphous phases.

Investigation of electronic and atomic structure of tribofilms on the surface of cutting tools with TiAlCrSiYN and multilayer TiAlCrSiYN/TiAlCrN coatings during machining of hardened steels

AbstractNanostructured single‐layer TiAlCrSiYN and multilayer TiAlCrSiYN/TiAlCrN coatings were deposited by a hybrid physical vapor deposition (PVD) coater with a plasma‐enhanced type arc source. Yttrium was added as a surfactant element to stabilize the nanostructure of the coating. The paper reports on the X‐ray photoelectron spectroscopy(XPS) and analysis of the extended energy loss fine structure(EELFS) spectroscopy studies of the electronic and atomic structure of tribofilms formed on the surface of cutting tools during high‐speed machining of hardened tool steels. It was shown by electron spectroscopy investigations that two types of tribofilms form on the surface of cutting tools. The first type is sapphire‐like (AlO) and mullite‐like (AlSiO) films with high protective ability. The second type has an amorphous‐like structure and a high density of dangling bonds enhancing their lubrication properties at elevated temperatures. This unique combination of thermal‐barrier and frictional characteristics of these tribofilms allows the cutting tool to stand high‐speed cutting conditions and achieve reliable tool life. A more intensive generation of mullite‐like tribofilms was observed in the single‐layer coating in contrast to the multilayer one, where generation of the sapphire‐like component prevailed. Most probably, the nanostructuring of the coating increases the interface and grain boundary diffusion and activates the formation of a high‐temperature tribo‐oxide. Copyright © 2010 John Wiley &amp; Sons, Ltd.