Structure and Tribological Properties of CrTiAlN Coatings Deposited by Multi-Arc Ion Plating

CrTiAlN coatings were prepared by using a home-made industrial scale multi-arc ion plating system. The coatings were found to be composites of face-center-cubic CrN and TiN. The surface roughness, microhardness, and tribological properties of the films were significantly affected by the nitrogen pressure and dc-pulsed bias voltage applied to the substrate. The CrTiAlN coatings with the smoothest surfaces were obtained at optimum conditions of nitrogen pressure of 5.0 Pa and bias voltage of -200 V. The samples were found to exhibit a hardness of 2900 HV0.05 with an average friction coefficient of 0.16 and wear rate of 1.5×10-16 m3/N?m against cemented carbide.     

Investigation of structure and mechanical properties of plasma vapor deposited nanocomposite TiBN films

TiBN coatings have huge potential applications as they have excellent properties with increasing modern industrial requirements.Nanocomposite TiBN coatings were synthesized on cemented carbide,high speed steel and Si substrates by using cathodic arc plasma ion plating from pure TiB_2 ceramic targets.The structure and mechanical properties of the TiBN coatings were significantly influenced by the nitrogen partial pressure.Rutherford backscattering spectrometry demonstrates that the nitrogen content of the coating varied from 2.8%to 34.5%and highresolution electron microscopy images reveal that all coatings have the characteristic of nanocrystals embedded in an amorphous matrix.The root-mean-square roughness of the coatings increases from 3.73 to 14.64 nm and the coefficients of friction of the coatings at room temperature vary from 0.54 to 0.73 with increasing nitrogen partial pressure.The microhardness of the coating increases up to 35.7 GPa at 10 seem N_2 flow rate.The smallest wear rate is2.65×10~(-15)m~3 N~(-1)m~(-1)which indicates that TiBN coatings have excellent wear resistance.The adhesion test revealed that the TiBN coatings have good adhesion at low nitrogen partial pressure.     

D.C.Plasma—Sprayed Coatings of Nanostructured Alumina—Titania—Silica

Nanocrystalline powders of w(Al2O3)=95%,w(TiO2)=3%,and w(SiO2)=2%,were reprocessed into agglomerated particles for plasma spraying,by using consecutive steps of ball milling,slurry forming,spray drying,and heat treatent,D.C.Plasma was used to spray the agglomerated nanocrystalline powders,and resultant coatings were depostied on the substrate of stainless steel,Scanning electron microscopy(SEM) was used to examine the morphology of the agglomerated powders and the cross section of the alumina-titania-silica coatings.Experimental results show that the agglomerated nanocrystalline particles are spherical,with a size from(10-90)um,The flow ability of the nanocrystalline powders is greatly improved after the reprocessing.The coatings deposited by the plasma spraying are mainly of nanostructure.Unlike conventional plasma-sprayed coatings,no laminar layer could be found in the nanostructured coatings.Although the nanostructured coatings have a lower microhardness than conventional microstructured coatings,the toughness of the nanostructured ceramic coatings is significantly improved.     

Low Friction-Coefficient TiBCN Nanocomposite Coatings Prepared by Cathode Arc Plasma Deposition

TiBCN nanocomposite coatings were deposited on cemented carbide and Si（100）by a cathode arc plasma system,in which TiB₂ cathodes were used in mixture gases of N₂ and C₂H₂.X-ray diffraction shows that TiB₂ and Ti₂B₅ peaks enhance at low flow rates of C₂H₂,but they shrink when the flow rate is over 200 seem.An increase of deposition rate was obtained from different TiBCN thicknesses for the same deposition time measured by scanning electron microscopy.Atomic force microscopy shows that the surface roughnesses are ¹0 nm and ²0 nm at C₂H₂ flow rates of 0-100 sccm and of 150-300 sccm,respectively.High resolution transmission electron microscopy and X-ray photoelectron spectroscopy show that the coatings consist of nanocrystal phases Ti₂B₅,TiB₂ and TiN,and amorphous phase carbon and BN.The average crystal sizes embedded in the amorphous matrices are 200 nm and 10 nm at C₂H₂ flow rates of200 sccm and 300 sccm,respectively.In Raman spectra,the D- and G-bands increase with C₂H₂flows at low flow rates,but weaken at high flow rates.The microhardness of the coatings decreases from 28.6 GPa to 20 GPa as the C₂H₂ increases from 0 sccm to 300 sccm,and the ball-on-disk measurement shows a dramatic decrease of the friction coefficient from 0.84 to 0.13.The reason for the reduced hardness and friction coefficient with the change of C₂H₂ flow rates is discussed.     

Mechanical Properties and Uniformity of Nanocrystalline Diamond Coating Deposited Around a Sphere by MPCVD

Nanocrystalline diamond coatings were deposited by MPCVD on the spheres used for a ball bearing.The nanocrystalline coatings with a grain size of 50 nm were confirmed by the surface morphology and composition analysis.The hardness of the coating is 20-40 GPa tested by nanoindentation,which is higher than that of tungsten carbide and silicon nitride substrates.The coating around the sphere observed from the Micro CT images is uniform with a thickness of12 μm.     

Effects of heat treatment and cooling rate on microstructural and mechanical characteristics of aluminide coatings on MANET steel

R & D studies concerning Pb-17Li blankets for DEMO suggest the use of coatings either as tritium permeation barriers for the water cooled blanket or as electrical insulators for the self cooled blanket. The production of coatings resistant to the thermal and mechanical stresses typical of the blanket operating conditions is the target. The present work describes the results of an experimental programme aimed at evaluating the effects of heat treatment and cooling rate on the microstructural and mechanical characteristics of aluminide coatings deposited on MANET steel (DIN 1.4914) by the hot-dipping process. The temperature of the post-deposition heat treatment that allows obtaining structures like FeAl and -Fe(Al), instead of the more brittle Fe_xAl_y intermetallics, has been identified. The coatings have been characterized by optical metallography, microhardness measurements, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and X-ray diffraction on the surface.     

Structure and tribological properties of Ti-containing amorphous carbon coatings prepared by cathode arc-enhanced middle-frequency magnetron sputtering

Ti-containing amorphous carbon （Ti-aC） coatings were deposited on cemented carbide and Si substratcs by cathode-arc-enhanced closed field middle-frequency unbalanced magnetron sputtering. The coatings were studied by using atomic force microscopy, Raman scattering, nanoindentation, and pin-on-disk testing. The measurements showed that the hardness of the coatings increased from 12 GPa at a Ti content of 1 at.% to 27 GPa at 31 at.%. The coatings exhibited different friction behaviors when facing different mating materials and changed with increasing Ti content, The coating with 4 at.% Ti exhibited excellent tribological performance with a low friction coefficient of 0.07 when facing the cemented carbide.     

CrN活塞环涂层的工艺制备与摩擦学性能研究

论文采用多弧离子镀技术在活塞环表面制备了CrN涂层,系统地研究了不同N2含量对CrN涂层的相结构和纳米硬度的影响规律.并采用CETR微动摩擦磨损试验机比较研究了Cr电镀层与CrN涂层的高温微动摩擦磨损性能,研究结果表明:随着N2含量的增加,薄膜由Cr2N(211)相过渡到CrN(220)相;膜层的纳米硬度随N2含量的增加而增大,并出现两个峰值;与Cr电镀层相比,CrN涂层主要以磨粒磨损为主,犁沟较窄且平滑,抗高温粘着磨损性能明显增强,而且摩擦系数较小,具有较好的摩擦匹配性能,更适合用于活塞环服役的高温磨损环境.     

Silicon carbide coating on molybdenum by chemical vapor deposition and its stability under thermal cycle conditions

Silicon carbide film (as thick as 25 μm) was chemically vapor deposited on molybdenum in the temperature range of 1050–1300°C by reaction of hydrogen and ethyltrichlorosilane as an application of a low-Z material to fusion reactor protective plates. The films were characterized by using scanning electron microscopy, X-ray diffraction, electron microprobe analysis, and infrared absorption spectroscopy. The deposits consisted of α and β-SiC and a small amount of SiO₂. Underlayer coatings were also attempted to improve the thermal cycling behavior. The coating with a boron underlayer was successfully cycled 2100 times between 800 and 1000°C, and then 560 times between 600 and 1200°C in air under thermal cycling conditions with a heating rate of 20°C/min. Problems in applying SiC-coated molybdenum to the first wall protective plates in a fusion reactor are discussed.     

离子束辅助沉积制备TiN/Si3N4纳米超硬膜的工艺研究

采用离子束辅助沉积法(Ion beam assisted deposition,IBAD)在单晶硅片上进行沉积制备了TiN/Si3N4纳米复合超硬薄膜;研究了辅助束流、轰击能量和Ti:Si靶面积比等工艺参数对TiN/Si3N4超硬纳米复合薄膜性能的影响.此外采用纳米硬度计、光电子能谱(X-ray photoelectron spectrum,XPS)和x射线衍射分析(X-raydiffraction,XRD)方法研究了纳米复合薄膜的性能、成分与组织结构;采用原子力显微镜(Atomic forcemicroscopy,AFM)分析了薄膜的表面形貌,并初步探讨了TiN/Si3N4纳米复合超硬薄膜的生长机理.     

Ion-beam irradiation effects on reactively sputtered CrN thin films

The present study deals with CrN/Si bilayers irradiated at room temperature (RT) with 120 keV Ar ions. The CrN layers were deposited by d.c. reactive sputtering on Si(1 0 0) wafers, at different nitrogen partial pressures (2 × 10⁻⁴, 3.5 × 10⁻⁴ and 5 × 10⁻⁴ mbar), to a total thickness of 240-280 nm. The substrates were held at room temperature (RT) or 150 °C during deposition. After deposition the CrN/Si bilayers were irradiated up to fluences of 1 × 10¹⁵ and 1 × 10¹⁶ ions/cm². Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and grazing angle X-ray diffraction (XRD). For the highest nitrogen pressure (5 × 10⁻⁴ mbar) a pure stoichiometric CrN phase was achieved. The results showed that Ar ion irradiation resulted in the variation of the lattice constants, micro-strain and mean grain size of the CrN layers. The observed microstructural changes are due to the formation of the high density damage region in the CrN thin film structure.     

活塞环N^＋离子注入的耐磨性对比试验

将Ｎ＾＋离子复合注入一组活塞环并与镀以氮化硅的一组活环以及厂家的一组成品环在同样的条件下进行快磨试验。试验结果表明，注入Ｎ＾＋离子的一组活平均磨损量及弹力变化均为最小。可见Ｎ＾＋离子注入对提高活塞环的耐磨性能是一种比较理想的方法。     

Increasing of Hardness of Titanium Using Energetic Nitrogen Ions from Sahand as a Filippov Type Plasma Focus Facility

In this paper a 90 kJ plasma focus facility was used to the bombardment of the titanium substrate using nitrogen ion beams. From x-ray diffraction patterns, we investigated the structure properties of titanium nitride layer has been successfully deposited on the titanium substrate such as grain size microstrain and dislocation density. In this work we observed the growth of in grain size with increasing a number of deposition shots. Decrease in dislocation density and microstrain at higher deposition is the another results we observed in this work. The topography and morphology of TiN samples was studied by scanning electron microscopy (SEM) and optical microscopy images. From SEM micrograph, damage of surface and creation of pits and cracks was reported. The goniometric test indicate increasing in contact angle of water drop for irradiated samples in respect to the unirradiated samples. The Knoop microhardness of the samples is increased about 500%. With increasing of nitrogen ion flux, the microhardness increases.     

Cr/CrN Compound Films Prepared by Ion Beam Assisted Deposition for Improving the Performance of Bearing Steel

With the development of industry, much attention has been paid to lengthening the life span of bearings. As reported in this paper, we investigated the Cr/CrN compound films formed on the specimens of W9Cr4V2Mo bearing steel by ion beam assisted deposition for improving the performance of bearing steels. The Vicker＇s microhardness, pin-on-disc, electrochemical measurement, XRD and SEM tests were used to characterize and analyze the treated samples. All results indicated that the mechanical properties of the treated samples were good, with the microhardness greater than that of the uncoated specimen, and the wear resistance, the passivity and pitting corrosion resistance increased considerably, the films possessed alternate Cr and CrN compound phases and produced different effects on the improvement of the performance of W9Cr4V2Mo bearing steels with different composing phases.     

Vacuum annealing enhances the properties of a tungsten coating deposited on copper by atmospheric plasma spray

A tungsten (W) coating (～900 μm) was deposited on a copper (Cu) substrate via the atmospheric plasma spray (APS) technique, and then annealed in vacuum. Measurements of microstructure, density, oxygen content, microhardness and thermal conductivity show that an appropriate thermal annealing treatment can dramatically improve the quality of the coating. The oxygen content was found to drop from 0.48 wt.% before annealing to 0.06 wt.% after; microhardness increased by about 50%; and thermal conductivity nearly doubled. These results indicate that a vacuum-annealed APS-W coating can match or even surpass the quality of W coatings deposited by vacuum plasma spray (VPS). Compared with VPS, annealed APS is a more convenient and cheaper method to obtain W coatings suitable for fusion applications.     

Superconductivity in MgB2 films synthesized by ablation from high-power ion beam

MgB₂ thin films with T_c = 19 K were fabricated by the ion ablation technique utilizing a high-energy pulsed ion beam. A target remains pure MgB₂ after ablation, proving the excellent capability of ablation by the high-power ion beam. Chemical compositions of the deposited material, however, may vary with positions of the substrates from the beam axis. X-ray diffraction patterns exhibit only (0 0 1) and (0 0 2) peaks, which indicate a c-axis orientation of the films. Scanning electron microscopy images show a possible growth of single crystals with hexagonal shape and 1 μm size.     

Characterization of Fe-based alloy coating deposited by supersonic plasma spraying

The objective of the present study is to characterize the Fe-based alloy coating deposited by the supersonic plasma spraying process. The condition of the melting particles was in situ monitored. The microstructure of the coating was examined by scanning electron microscope and high resolution transmission electron microscope. The phase composition was examined by X-ray diffraction. The microhardness and porosity were also measured, respectively. Results show the prepared coatings have excellent properties, such as few oxides, high microhardness and a low porosity amount. At the same time, a mass of amorphous/nanocrystalline phases was found in the coating. The mechanism of the formation of amorphous/nanocrystalline phases was investigated. The appropriate material composition of spraying material and flash set process of plasma spraying are the key factors. Moreover, the mechanism for oxidation resistance is also investigated, where the separation between melting metal and oxygen by the formation of SiO₂ films is the key factor.     

Effect of heat-treatment at different temperatures on the phase and morphology of the surface of W-coated C/C composites

W-coated carbon/carbon composites have been considered as an attractive plasma facing material for ITER. W coatings were prepared on carbon/carbon substrates by double glow plasma. W-coated carbon/carbon substrates were heat-treated in a vacuum furnace at 1000, 1100, 1200, 1300 and 1400 °C for 1 h. The coatings were examined by X-ray diffraction for phase identification. The microstructure was observed by scanning electron microscopy. The chemical composition was analyzed by energy dispersive X-ray spectroscopy. The Vickers hardness was measured with a microhardness tester. The results indicated that the critical temperature for generating WC was 1200 °C. When the coatings were heat-treated below 1200 °C, the diffusion of W and C played a dominant role. W grains in 1100 and 1200 °C heat-treated samples presented a diffusion-induced rearrangement around the carbon fibers or the pores on the surface of C/C substrate. The amount of W and the hardness of the heat-treated coatings were reduced as the temperature increased. However, the reaction of W and C played a dominant role above 1200 °C. The amount of WC and the hardness of the heat-treated coatings were greatly increased as the temperature increased.     

CrTiAlN复合涂层硬质合金刀具的制备与切削性能研究

利用多弧离子镀技术在YT14硬质合金刀具上制备了CrTiAIN复合涂层,对不同偏压条件下CrTiAIN复合膜的表面形貌、硬度、结合性能进行了系统研究,采用X射线衍射分析技术(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)等现代材料分析技术对CrTiAIN复合涂层的微观组织结构进行了分析表征,结果表明:CrTiAIN复合涂层的主要成分为Cr、Ti、Al、N、O,相组成为Cr、CrN、Cr2N和TuN晶体相与AIN非晶相.在干式切削条件下,不同涂层刀具的切削寿命的排序依次为:CrrnAlNTiAINTiN未涂层,同时对不同涂层刀具的耐磨损特性进行了讨论分析.     

Regular surface patterns by local swelling induced by He implantation into silicon through nanosphere lithography masks

Nanopatterning of silicon surfaces by means of He⁺ ion implantation through self-organized colloidal masks is reported for the first time. Nanosphere lithography (NSL) masks with mask openings of 46–230 nm width were deposited on Si(1 0 0) wafers. He⁺ ions were implanted through these masks in order to induce a local cavity formation and Si surface swelling. The surface morphology and the subsurface structure were studied using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM), respectively, as a function of mask and implantation parameters. It is demonstrated that regular arrays of both individual hillocks and trough-like circular rings can be generated.