Cathodic Plating Research Articles

SURFACE CHARACTERISTICS AND WEAR RESISTANCE OF AlCrTiSiN COATINGS AT HIGH TEMPERATURES

AlCrTiSiN coatings were deposited on YT14 cemented carbide using cathodic arc ion plating (CAIP) method. The surface and cross-section morphologies, chemical composition, phases, surface roughness, and binding energies of chemical elements of obtained coatings were analyzed using a field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), respectively, and its mechanical properties were characterized using a scratch tester and nanoindentation tester. The friction-wear behaviors of AlCrTiSiN coatings at 700∘C, 800∘C and 900∘C were investigated using a high temperature wear test, the distributions of chemical elements on the worn tracks were analyzed using a plane scan analysis of EDS, and the high temperature wear mechanisms were also discussed. The results show that the chemical elements are uniformly distributed on the AlCrTiSiN coating with the surface roughness of 105[Formula: see text]nm, which is composed of faced centered cubic (FCC)–(Cr, Al)N, body-centered cubic (HCP)–AlN and Si3N4 amorphous phases. The interfacial bonding strength, microhardness and elastic modulus of AlCrTiSiN coating is 26.15[Formula: see text]N, 25.789[Formula: see text]GPa, and 251.364[Formula: see text]GPa, respectively. The average coefficient of friction (COF) of AlCrTiSiN coatings at 600∘C, 700∘C and 800∘C is 1.06, 0.73, and 0.97, respectively, of which friction performance is the best at 700∘C. The wear mechanism of AlCrTiSiN coating at 600∘C, 700∘C and 800∘C is adhesive wear [Formula: see text] fatigue wear, abrasive wear [Formula: see text] oxidation reaction, and adhesive wear [Formula: see text] fatigue wear, respectively.

Effect of N2 flow rate on structural and infrared properties of multi-layer AlCrN/Cr/AlCrN coatings deposited by cathodic arc ion plating for low emissivity applications

The effect of N2 flow rate on structural, composition, deposition rate, electrical and infrared properties of the multi-layer AlCrN/Cr/AlCrN tandem coatings have been studied. The coatings were designed and prepared by a cathodic arc ion plating system at various N2 flow rates for low emissivity applications. The results showed that the thickness of AlCrN layers decreased continuously with increasing N2 flow rate. Structure and elemental composition of the deposited coatings strongly depended on N2 flow rate. X-ray diffraction analysis showed that for 10–80 sccm, the coatings exhibited a single (fcc) phase, for 120–160 sccm, an amorphous phase was obtained. The phase formation has been confirmed by transmission electron microscopy diffraction patterns. As for electrical resistivity, the AlCrN layers turned from conductive, semiconductive, to dielectric behavior. In practice for low emissivity applications, the deposited multi-layer coatings exhibited emissivity values among 0.0748–0.1193, which rose with increased N2 flow rate. Among all the phases, the coating with an amorphous AlCrN layer (160 sccm) presented an outstanding thermal stability and had an emissivity of 0.1194 even after annealing at 800 °C for 10 h in air. It was observed that the amorphous AlCrN layer effectively controlled the inward diffusion of O and the outward diffusion of Cr, Al and Ni from substrate, which rendered this multi-layer coating a potential material for low emissivity applications at high temperature.

Salt spray corrosion and electrochemical corrosion characteristics of CAIP and LTPN fabricated AlCrN/NL composite coating

An AlCrN/nitrided layer (NL) composite coating was fabricated on H13 hot work mould steel using a cathodic arc ion plating (CAIP) and low temperature plasma nitriding (LTPN). The surface and cross–section morphologies, chemical composition and phases of obtained coating were characterized using a scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and x-ray diffractometer (XRD), respectively. The salt spray corrosion (SSC) and electrochemical corrosion properties of AlCrN/NL coating in 3.5 wt% NaCl solution were analyzed using a salt spray corrosion chamber and electrochemical workstation. The results show that the AlCrN/NL composite coating consists of AlN, Cr1.75V0.25N2, AlCrFe2 and SiC phases, the formation of ceramic phases increases its corrosion resistance. The aggressive Cl– is adhered on the corrosion products after the SSC test, the corrosive micro–cells and pitting corrosion are formed due to the differences of structure and relative potentials. The corrosion current densities of AlCrN/NL coating, NL and substrate are 3.255 × 10–6, 9.848 × 10–6, and 1.522 × 10−5 A · cm–2, respectively, indicating that the corrosion resistance of AlCrN/NL coating is higher than that of NL and substrate. The polarization resistance of 11 798 Ω · cm2 on the AlCrN/NL coating is 1.68 and 3.67 times higher than that of NL and substrate, respectively, which shows that the AlCrN/NL coating increases the corrosion resistance of substrate.

Thermal shocking resistance of AlCrNO-based solar selective absorbing coating prepared by cathodic arc plating

Thermal shocking resistance is an important property of the solar selective absorber coating applied in solar power plant. In this paper, we reported the thermal shocking resistance of AlCrNO-based solar selective absorbing coating which was prepared by cathodic arc plating. The coating endured 100 cycles of thermal shocking test, and in each cycle, the sample was heated to 600 °C at a heating rate over 200 °C/min and then cool down to room temperature at a cooling rate over 150 °C/min. After 100 cycles, optical properties, morphologies, elements, phase structure, and surface roughness of the sample were detected by spectrophotometers, scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and atomic force microscope (AFM). According to the results, α/ε of the sample after thermal shocking test changed from 0.93/0.20 to 0.94/0.21, which expressed that the coating possessed perfect thermal shocking resistance. Similar to the sample after thermal aging test, the content of nitride of the coating increased, and threshold of reflectance shifted red. But reflectance pattern of the sample after thermal shocking test was different from it of the sample after thermal aging test because micro defects appeared on the surface of the coating after thermal shocking test.

High performance aperiodic metal-dielectric multilayer stacks for solar energy thermal conversion

A novel spectrally selective Cr/AlCrN/AlCrNO/AlCrN/AlCrNO/AlCrO multilayer coating was deposited on stainless steel substrates using cathodic arc ion plating. In this tandem absorber coating, Cr, AlCrN, AlCrNO and AlCrO act as the reflector layer, semi-absorbing layer, the main absorbing layer and the antireflection layer, respectively. The spectral properties of this multilayer coating during long-term annealing in air have been investigated with the aim of evaluating the thermal stability of this aperiodic metal-dielectric multilayer stacks. An average absorptance of 0.90 and emittance of 0.15 are achieved in this multilayer coatings fabricated with optimized parameters. More importantly, the coating exhibits an outstanding thermal stability with a selectivity of 0.94/0.11 even after annealed at 500 °C for 1000 h in air. The microstructure analysis indicate that the multilayer coating consists of aperiodic AlCrN and AlCrON layers in addition to the Cr and AlCrO layers. After the long-term annealing, small amounts of AlN, CrN and Cr2N nanocrystallites are observed to be homogeneously embedded in the AlCrN and AlCrON amorphous matrices. The nanoparticles in the AlCrN and AlCrON layers can effectively scatter the incident light into a broadband wavelength range, increasing the optical path length in the absorbing layers and thus resulting in a pronounced enhancement in the absorptivity. A handful of Cr2O3 and Al2O3 nanograins are observed to embedd in the amorphous AlCrO antireflection layer, which can efficitively reflect the solar infrared radiation and the thermal emittance from the substrate and thus result in pretty low infrared emissivity. The good thermal stability is attributed to the excellent thermal stability of the cermet-based amorphous matrices and the sluggish atomic diffusion in the nanoparticles, which could effectively slow down the inward diffusion of oxygen and avoid agglomeration of naonparticles. These results suggest that the AlCrON-based selective absorbing coating is a good candidate for photo-thermal conversion at high temperatures.

Effect Ti/AlTiN Multilayer Coating on the Crater Wear Process of Cutting Tool and Tribological Properties

Tool wear is a major problem in machining operations because the resulting material loss gradually changes of the machine tool. There many factors may leads to material loss like; friction, corrosion, and also it’s happened by rubbing during machining processes between the work piece and the tool. Dimensional accuracy of the work piece, and also the surface finish will be reducing by tool wear. It can also increase cutting force. In this study, we focused on the effect of the coating process on crater wear problems. Crater wear is caused by the flow between the chip and the rake face of the tool, whereas flank wear is caused by the contact between the tool and the work piece. In reducing crater wear, aluminum titanium nitride (AlTiN) using Al0.67 Ti0.33 in cathodic arc plating system is considered effective as a tools coating material. In reducing flank wear, AlTiN is also deemed as the best tool coating material. Experimentally, the use of Ti/AlTiN-coated tools has been proven effective in reducing crater wear. In this study, the roughness Ra values of the (Ti/AlTiN) coatings were (0.14, 0.15, 0.23, 0.02, 0.21) µm at values of layers thickness (1.138, 1.518, 1.735, 2.717, 3.0818) µm, respectively. The lowest COF appeared at thickness 2.717 µm and the high coefficient of friction of the Ti/AlTiN coating was a result of high roughness and the large contact surface area of the system coating steel ball. The two most important parameters used to measure crater wear are length and width of wear.

Electrochemical Polishing of Lithium Metal Surface for Highly Demanding Solid‐Electrolyte Interphase

AbstractLithium metal has shown great promise as an anode material for high‐energy rechargeable batteries. However, interfacial instability caused by an unstable solid‐electrolyte interphase (SEI) and dendrite growth has impeded the realization of Li anodes for practical applications. Recently, we reported a potentiostatic stripping−galvanostatic plating electrochemical polishing method to simultaneously create atomically flat Li and a molecularly smooth SEI, leading to a near‐perfect Li anodes that exhibit much enhanced electrochemical performance. In this paper, key factors including anodic stripping potentials, cathodic plating current densities, and types of salt and solvent systems are further investigated in detail based on the understanding of electrode reactions taking place during polishing. In particular, the importance of considerations on the mutual constrains between electropolishing and SEI formation and, thus, the necessity of fine control of potential and/or current is elucidated, which serves as a general rule for the successful application of electrochemical polishing of Li as well as other metals that involve the formation of SEIs.

Spectral properties of AlCrNO-based multi-layer solar selective absorbing coating during the initial stage of thermal aging upon exposure to air

A spectrally selective Cr/AlCrN/AlCrNO/AlCrO multi-layer absorber coating has been designed and deposited on stainless steel substrates by the cathodic arc ion plating technique. The spectral properties of the multi-layer coating during the initial stage of thermal aging in air were investigated with the aim of achieving a basic understanding of its relation to microstructure. The composition, structure and surface morphology of the coatings were characterized using XRD, SEM, XPS, TEM and AFM, while the optical properties of the coatings were measured by spectrophotometers. The experimental results indicate that the multi-layer coating with a high solar absorptance of 0.90 and a relatively low emittance of 0.15 are obtained through parameter optimization. The structure analysis suggests that the as-deposited AlCrN and AlCrNO layers, acting as the main absorbers, are consisted of the AlN, Cr2N and AlN, CrN, Cr2N nanocrystallites embedding in amorphous matrix, respectively. While the AlCrO layer, acting as the anti-reflection layer, is consisted of mainly amorphous. After annealing at 500 °C for 2 h in air, a solar selectivity of 0.94/0.12 was achieved while the thermal emittance attained 0.25 at 500 °C. Based on the microstructural analysis, the enhancement in absorptance of the multi-layer AlCrNO-based coating during the initial stage of thermal aging could be attributed to the decomposition of Cr2N nanocrystallites and the recrystallization of the AlCrN and AlCrNO layers. While the enhanced emittance after annealing can be ascribed to the decomposition of the macro-droplets and the decrease of surface roughness. These results could provide new insights into rational use of the muti-layer coatings and spectral properties tuning of solar-selective functional multi-layer coatings and thus promote the development of coatings for photo-thermal conversion at high temperatures.

Effect of bilayer period on microstructure and mechanical properties of TiSiN/TiN coatings

A potentially enhanced mechanical properties of TiSiN based multilayered coatings, as a consequence of e high density interface, has attracted much attention both to understand the strengthen mechanism and to develop them for the wear protection of cutting tools. Here, the effects of bilayer period on microstructural and mechanical properties of TiSiN/TiN nano-composite multilayers produced by cathodic arc ion plating using 2-fold rotation technique on Si(100) and cemented carbide substrate were investigated. Cross-sectional morphologies revealed that the bilayer period in these samples were in range of 16–60 nm as the SRS decreased from 6 to 2 rpm (rotation per minute). As shown by EDS results, the contents of Ti and Si were similar in all samples. The hardness first increased with the increase of SRS and then decreased. Maximum hardness was obtained in TiSiN/TiN coatings deposited with a bilayer period of 22.5 nm, which also revealed the lowest average friction coefficient.

Characterization and friction–wear behaviors of cathodic arc ion plated AlCrTiN coating on HVOF sprayed WC–12Co coating at elevated temperatures

An AlCrTiN coating was deposited on high velocity oxygen fuel (HVOF) sprayed WC–12Co coating using a cathodic arc ion plating (CAIP). The surface and cross–section morphologies, chemical elements, and phases of obtained AlCrTiN coating were analyzed using a scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and x–ray diffractometry (XRD), respectively, and its surface roughness and chemical valences were analyzed using a atomic force microscopy (AFM) and x–ray photoelectron spectroscopy (XPS), respectively. The mechanical properties such as nanohardness and modulus of elasticity and bonding strength of AlCrTiN coating was measured using nanoindentation and scratch tests, respectively. The friction–wear behaviors were evaluated at 600, 700 and 800 °C using a high temperature pin–on–disc tribometer. The results show that the AlCrTiN coating presents a (111) preferred orientation, its nanohardness and modulus of elasticity is 22.09 and 347.52 GPa, respectively, and its bonding strength is 32.9 N. The average coefficient of friction (COF) at 600, 700 and 800 °C is 1.40, 1.24, and 0.76, respectively, and the corresponding wear rate is 5.13 × 10–6, 5.71 × 10–6 and 14.16 × 10–6 mm3 · N–1 · s–1, exhibiting the reducing friction and decreasing wear at high temperatures, the wear mechanism is primary abrasive wear and oxidation wear.

The high temperature and varying temperature tribological performance of TiC coatings

TiC coatings were deposited on the AISI304 sheets by cathodic arc ion plating using pure Ti target in Ar/CH4 atmosphere. The surface morphology, hardness and tribological properties were investigated by scanning electron microscope(SEM), micro-hardness tester and ball-on-disc rotating tribometer. The results show that the thickness of the coatings was about 6μm. The hardness was 2000Hv0.05. The tribological tests were carried out at RT, 200°C, 400°C and RT-400°C against alumina balls. The friction coefficient was stable at 0.57 at RT, while the coefficient fluctuated largely at 200°C and RT-400°C due to the lower relative humidity.

Microstructure and friction-wear performances of cathodic arc ion plated TiAlSiCN coatings on YT14 cemented carbide cutting tools

PurposeThe purpose of this study was to develop a TiAlSiCN coating with high bonding and hardness, ultra-low friction and good lubrication characteristics, which provided an experimental basis for the surface modification of YT14 cemented carbide cutting tools.Design/methodology/approachIn this work, a TiAlSiCN coating was deposited on YT14 cemented carbide cutting tool through cathodic arc ion plating. The surface-interface morphologies, distributions of chemical elements, phases, bonding energy and surface roughness were analyzed using field emission scanning electron microscopy, energy-dispersive spectroscopy (EDS), X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy, respectively, and the coating the bonding strength were quantitatively characterized with a scratch.FindingsThe average COFs of the TiAlSiCN coating at 700°C, 800°C and 900°C were 0.68, 0.57 and 0.38, respectively, showing that the TiAlSiCN coating was an effective lubricant at a high temperature, and the wear rate of the coating increases with wear temperature. After wearing at 700°C, 800°C and 900°C, the Ti, Si and N elements form atom-poor regions, while Al forms an atom-rich region, showing that the oxides of Ti, Al and Si are formed to improve the wear resistance of the coating. The wear mechanism of TiAlSiCN coating at high temperatures was composed of abrasive wear and oxidation wear.Originality/valueThe friction-wear behaviors of TiAlSiN coating were investigated using an HT-1000-type high-temperature friction wear tester, and the worn tracks on the coatings were analyzed using an EDS plane scan, thus obtaining the wear mechanism of TiAlSiN coating.

Hole conduction characteristics of cubic Ti1−xAlxN

Cubic Ti1−xAlxN (x = 0.5, 0.6) films were deposited using RF (radio frequency) magnetron sputtering and cathodic arc ion plating methods on a thermally oxidized Si substrate to evaluate the temperature dependence of their electrical characteristics by Hall measurements from 10 K to 295 K. The temperature dependence of the hole concentration and the electrical conductivity above about 200 K shows that cubic TiAlN in this study had semiconductor characteristics, indicating that the hole conduction in the valence band is dominant in a high temperature range above about 200 K. In contrast, the variable range hopping conduction is dominant in a low temperature range below about 100 K. In addition, the hole mobility of Ti0.4Al0.6N deposited by RF sputtering increased with increasing temperature above 220 K, even though the phonon scattering increases. This result shows that a disordered grain boundary between polycrystalline TiAlN acts as a barrier layer for the hole conduction.

Investigation on oxidation behaviors of Ti-Si-N coating at high temperature

PurposeTi-Si-N coating with nanocomposite structure is a promising protective coating for cutting tools which will be subject to high temperature oxidation during service. This study aims to investigate the thermal stability of Ti-Si-N coatings and lays the foundation for its application in high speed dry cutting.Design/methodology/approachNanocomposite Ti-Si-N coating was deposited on stainless substrate and silicon wafer (100) by Ti90Si10 alloy target by using cathodic arc ion plating. The microstructure of Ti-Si-N coating had been detected by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).FindingsThe results suggested that the coating was TiN nanocrystals with a diameter of 6.3 nm surrounded by amorphous Si3N4. The oxidation test was conducted under 550, 650, 750, 800, 850, 900 and 950°C for 2 h. The structure evolution was observed by Scanning electron microscope (SEM), energy dispersive spectrum (EDS), XRD and XPS. The results indicated that rutile has been formed at 650°C, while Si3N4 began to oxidized at 800°C. The grain size of TiN increased from 6.3 to 13 nm as the samples oxidized from 550 to 800. Micro-crack also formed in samples oxidized over 900°C.Originality/valueTi-Si-N coating, in this study, was deposited by cathodic arc ion plating using alloy target at high-bias voltage. The oxidation temperature ranged from 500 to 950°C with TiN coating as reference.

Microstructure and Tribological Properties of Cathodic Arc Ion Plated TiAlN and TiSiN Coatings at High Temperatures

TiAlN and TiSiN coatings were deposited on YT15 cemented carbide using a cathodic arc ion plating (CAIP). The surface-cross section morphologies, chemical elements, surface roughness, phases, and chemical valences of as-obtained coatings were analyzed using a scanning electron microscopy (SEM), energy dispersive spectroscopy, atomic force microscopy (AFM), X-ray diffractometer (XRD), and X-ray photoelectron spectroscopy (XPS), respectively, and the bonding strength, hardness and Young's modulus of TiAlN and TiSiN coatings were measured using a scratch tester and nano-indentation, respectively, and the wear mechanism at high temperatures was also discussed. The results show that the surface roughness of TiAlN and TiSiN coatings is 69.1 and 58.0 nm, respectively, and the corresponding average particle size is 998.8 and 817.2 nm, respectively. The TiAlN coating is composed of TiAlN and AlN, while the TiSiN coating is composed of TiN and Si3N4. The bonding strength of TiAlN and TiSiN coatings is 84.3 and 72.6 N, respectively, the hardness and Young's modulus of TiAlN coating is 23.67 and 415.80 GPa, respectively, while that of TiSiN coating is 20.46 and 350.40 GPa, respectively. The average coefficients of friction (COFs) of TiAlN and TiSiN coatings are 0.4516 and 0.4807, respectively; the corresponding wear rate is 589.7 × 10−6 and 4142.2 × 10−6 mm3 N−1 s−1, respectively; the wear mechanism of TiAlN and TiSiN coatings is oxidation wear and abrasive wear.

Atomic force microscopy analysis of cathodic arc ion-plated CrN and CrC coatings

Coatings of CrN and CrC were deposited on a YT14 cemented carbide cutting tool using cathodic arc ion plating (CAIP). The surface and interface morphologies of the as-obtained CrN and CrC coatings were analyzed using a field emission scanning electron microscope. The heights, particle diameters and power spectral densities of CrN and CrC coatings were analyzed using atomic force microscopy and the correlated parameters of roughness were obtained. The results show that the roughness of the CrN and CrC coatings is 81.7 × 10−3 and 70.2 × 10−3 nm, respectively, and CAIP has little effect on the CrN and CrC coating roughness. The height of the peak values of CrN and CrC coatings is 0.498 and 0.502 nm, respectively, and the reduction friction of the CrN coating was slightly better than that of the CrC coating. The average particle diameter of the CrN and CrC coatings is 6.575 × 102 and 7.678 × 102 nm, respectively, and the particles are uniformly distributed with no large-scale fluctuations. The power between the cursors of the CrN and CrC coatings is 1.44 × 10−2 and 9 × 10−3 nm2, respectively, with the power spectral density of the CrN coating being the dominant frequency.

Friction and wear performances of cathodic arc ion plated TiAlSiN coating under oil lubricated condition

TiAlSiN coating was deposited on H13 hot work mould steel using cathodic arc ion plating (CAIP). The surface-interface morphologies and phases of the obtained coating were analyzed using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively, and the morphologies, distributions of chemical elements and profiles of worn tracks were also researched using scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), and optical microscope (OM), respectively. The friction-wear performances of TiAlSiN coating under oil lubricated and dry fiction conditions were investigated, and the wear mechanisms of TiAlSiN coating were discussed. The experimental results show that the coating is primarily composed of (Ti, Al)N, AlTiN, and TiN hard phases, Si3N4 exists between the (Ti, Al)N crystal grains, increasing the coating microhardness to 3200HV. The TiAlSiN coating has excellent performances of reducing friction and wear resistance, the average coefficient of friction (COF) of TiAlSiN coating under oil lubricated condition is only 0.05, lowered than the average COF of 0.211 under dry friction condition, the wear rate decreases by about 81.2% compared with that under dry friction condition. The wear mechanism of TiAlSiN coating under oil lubricated and dry friction conditions is composed of abrasive wear, fatigue wear, and abrasive wear, respectively. The internal friction of oil lubrication is a main factor of decreasing fatigue wear.

EFFECTS OF LOADS ON HIGH-TEMPERATURE FRICTION-WEAR PROPERTIES OF CATHODIC ARC ION PLATED TiALSiN COATINGS

A TiAlSiN coating was deposited on H13 hot work mould steel using a cathodic arc ion plating (CAIP). The friction-wear performances of the obtained coating under different loads were characterized on an HT-1000 type high temperature tribological tester at 800[Formula: see text]C. The morphologies and chemical compositions of the worn tracks were analyzed using a scanning electronic microscope (SEM) and its configured energy dispersive spectrometer (EDS), respectively, and the corresponding wear mechanisms were discussed. The results show that the average coefficient of friction (COF) of the TiAlSiN coating at the loads of 2, 4 and 6[Formula: see text]N is 0.3072, 0.3040, and 0.4114, respectively, the COFs of the coating are stable at the loads of 2 and 4[Formula: see text]N, while those at the load of 6[Formula: see text]N are obviously increased. Under the load of 2[Formula: see text]N, a small amount of large and scattered white debris disperses on the worn track, the wear mechanism is adhesive wear. While the white wear debris appears on the worn track under the load of 4[Formula: see text]N, the COFs are relatively stable, due to the effects of oxide layer on the worn track, and the wear mechanism is abrasive wear and oxidation wear. Under the load of 6[Formula: see text]N, a number of shallow grooves and cracks appear on the worn tracks, showing that the coating is basically worn out, the wear mechanism is abrasive wear and oxidation wear.

Microstructures and Friction–Wear Behaviors of Cathodic Arc Ion Plated Chromium Nitride Coatings at High Temperatures

A chromium nitride (CrN) coating was deposited on YT14 cemented carbide using a cathodic arc ion plating (CAIP). The high temperature friction and wear of the obtained coating were investigated using a wear test. The results show that the Cr and N form the atom-rich zones in the coating. The average coefficient of friction (COF) of CrN coatings at 300 °C, 400 °C, and 500 °C is 0.50, 0.62, and 0.43, respectively. The wear mechanism of CrN coating at 300 °C and 400 °C is abrasive wear, and that at 500 °C is abrasive wear, accompanied by slight oxidation wear.

Effect of frequency on fretting wear behavior of Ti/TiN multilayer film on depleted uranium.

The Ti/TiN multi-layer film was prepared on the depleted uranium (DU) substrate by cathodic arc ion plating equipment. The character of multi-layer film was studied by SEM, XRD and AES, revealed that the surface was composed of small compact particle and the cross-section had a multi-layer structure. The fretting wear performance under different frequencies was performed by a MFT-6000 machine with a ball-on-plate configuration. The wear morphology was analyzed by white light interferometer, OM and SEM with an EDX. The result shows the Ti/TiN multi-layer film could greatly improve the fretting wear performance compared to the DU substrate. The fretting wear running and damaged behavior are strongly dependent on the film and test frequency. The fretting region of DU substrate and Ti/TiN multi-layer under low test frequency is gross slip. With the increase of test frequency, the fretting region of Ti/TiN multi-layer change from gross slip to mixed fretting, then to partial slip.