Structure,hardness and tribological properties of nanolayered TiN/TaN multilayer coatings

TiN/TaN coatings, consisting of alternating nanoscaled TiN and TaN layers, were deposited using magnetron sputtering technology. The structure, hardness, tribological properties and wear mechanism were assessed using X-ray diffraction, microhardness, ball-on-disc testing and a 3-D surface profiler, respectively. The results showed that the TiN/TaN coatings exhibited a good modulation period and a sharp interface between TiN and TaN layers. In mutilayered TiN/TaN coatings, the TiN layers had a cubic structure, but a hexagonal structure emerged among the TaN layers besides the cubic structure as the modulation period went beyond 8.5 nm. The microhardness was affected by the modulation period and a maximum hardness value of 31.5 GPa appeared at a modulation period of 8.5 nm. The coefficient of friction was high and the wear resistance was improved for TiN/TaN coatings compared with a homogenous TiN coating, the wear mechanism exhibited predominantly ploughing, material transfer and local spallation.     

Influence of multi-interfacial structure on mechanical and tribological properties of TiSiN/Ag multilayer coatings

The TiSiN/Ag multilayer coatings with bilayer periods of ~50, 65, 80, 115, 150, and 410 nm have been deposited on Ti6Al4 V alloy by arc ion plating. In order to improve the adhesion of the TiSiN/Ag multilayer coatings, TiN buffer layer was first deposited on titanium alloy. The multi-interfacial TiSiN/Ag layers possess alternating TiSiN and Ag layers. The TiSiN layers display a typical nanocrystalline/amorphous microstructure, with nanocrystalline TiN and amorphous Si₃N₄. TiN nanocrystallites embed in amorphous Si₃N₄ matrix exhibiting a fine-grained crystalline structure. The Ag layers exhibit ductile nanocrystalline metallic silver. The coatings appear to be a strong TiN (200)-preferred orientation for fiber texture growth. Moreover, the grain size of TiN decreases with the decrease of the bilayer periods. Evidence concluded from transmission electron microscopy revealed that multi-interfacial structures effectively limit continuous growth of single (200)-preferred orientation coarse columnar TiN crystals. The hardness of the coatings increases with the decreasing bilayer periods. Multi-interface can act as a lubricant, effectively hinder the cracks propagation and prevent aggressive seawater from permeating to substrate through the micro-pores to some extent, reducing the friction coefficient and wear rates. It was found that the TiSiN/Ag multilayer coating with a bilayer period of 50 nm shows an excellent wear resistance due to the fine grain size, high hardness, and silver-lubricated transfer films formed during wear tests.     

基于RFPECVD方法不锈钢上沉积类金刚石薄膜的机械与摩擦特性

讨论用射频等离子体增强化学气相沉积(RFPECVD)工艺,在室温下实现在1Cr18Ni9Ti不锈钢基底上镀类金刚石(DLC)膜.为提高DLC膜的结合力,首先在不锈钢基底上沉积Ti/TiN/TiC功能梯度膜.借助所设计的界面过渡层,成功地在不锈钢基底上沉积了一定厚度的DLC膜.通过优化沉积参数,所沉积的DLC膜在与100Cr6钢球对磨时摩擦系数低于0.020.在摩擦过程中DLC膜的磨损机制借助SEM、Raman分析进行了研究.     

Correlation between structure and optical properties in low emissivity coatings for solar thermal collectors

We have investigated the relation between the structure and morphology of TiN coatings with their optical properties. Samples were deposited by magnetron sputtering and, by changing the deposition parameters, different textures and chemical compositions can be obtained as measured by X-ray diffraction and glow discharge optical emission spectroscopy respectively. The transmittance in the visible range, measured by spectroscopic ellipsometry, and the emittance, derived from reflectance in the far infrared range as measured by Fourier Transform Infrared Spectroscopy have been related to the nitrogen atomic content and the preferred crystalline orientations present in the TiN coatings. The visible transmittance of the coatings was found not to be dependent on the preferential orientation, while the emittance clearly improves with increasing the film thickness and the presence of both (111) and (200) crystal orientations.     

氮化物硬质涂层中Cr、Ti和Al元素对摩擦磨损特性的影响

利用四靶闭合场非平衡磁控溅射(CFUBMS)技术在石英玻璃和抛光不锈钢片两种基底上制备含有Cr、Ti和Al元素组合的各种氮化物涂层.采用摩擦磨损仪测试涂层摩擦系数,应用金相显微镜对各个涂层磨痕形态进行分析,结果表明TiN、CrN、TiAlN、CrAlN以及CrTiAlN涂层的摩擦系数依次减小,耐磨特性依次提高;结合涂层的X射线光电子能谱分析,可以得到含有Al元素涂层中形成了AlN的结构,提高涂层的硬度,增加耐磨特性;在涂层中含有Cr元素形成了氧化物Cr2O3可以提高涂层自排屑能力,减小摩擦系数,增加耐磨特性,含Ti元素形成的氧化物TiO2则不利于涂层的摩擦磨损特性;由于CrTiAlN本身具有比三元氮化物更高的涂层硬度,且含有Al和Cr元素,因此该涂层具有最好的摩擦磨损性能.     

Preparation and characterization of r.f.-sputtered multilayered TiN---Au films

TiN---Au films with multiple intermediate layers deposited by r.f. sputtering are suggested as a solution to the problem of adhesion of gold films to TiN coatings. Their optical and mechanical properties are investigated and compared with those of conventional electroplated gold films. Various analysis techniques have been used: Auger electron spectroscopy to determine the composition profiles, the direct tensile test for adhesion characteristics, optical rub test for scratch characteristics, salt spray test for corrosion characteristics and the selected ordinate method to identify the color of resultant films. It is shown that poor adhesion of gold films of TiN coatings can be overcome. Resultant multilayered TiN---Au films show the same color as that of commercially available electroplated gold films and their reflectivity reaches 98% of that of gold films over the wavelength range studied. For further applications, electrical properties of multilayered TiN---Au have also been studied. The sheet resistance of these TiN---Au films on n-Si and p-Si is in the range 0.54ω/□–6.12ω/□. Thus these multilayered structures may be used as durable contacts for microelectronic applications.     

Wear resistant composite coatings

In the search for wear resistant coatings, nanolaminated composite films composed of alternating metallic and ceramic layers, namely, Al/Al₂O₃ and Ti/TiN were produced using radio frequency magnetron sputtering. The metal layer thickness in the as-sputtered films of Al/Al₂O₃ ranged from 70 to 500 nm, and 150 to 450 nm in Ti/TiN. The non-metals (Al₂O₃ and TiN) layer thicknesses ranged from 10 to 40 nm and total film thicknesses of 10–15 µm. All coatings were characterized and tested for their tribological properties. Friction and wear tests were performed under non-lubricated sliding conditions using a pin-on-disc type tribometer. The coefficient of friction of the composite coatings tested, against a stainless steel pin, varied with the sliding distance. At the early stages of sliding the coefficient of friction rose to a peak, followed by a decrease to a steady-state value. Wear rates and coefficients of friction were related to the hardness and to the structure refinement of the coatings.     

Producing Multilayer Coatings from the Gas Phase with the Participation of TiC and TiN Compounds on the Hard Alloy VK8

The phase and chemical compositions, structure, thickness, microhardness, operational properties of the VK8 hard alloy with multilayer coatings produced by the methods of diffusion titanizing, titanoalitizing, nitriding, nitridotitanoalitizing have been studied. The last two methods combine the nitriding at a temperature of 540°C for 20 h followed by titanizing or titanonitriding. It has been established that the composition of TiN, TiC layers formed at the nitrotitanoalitizing fulfils barrier functions at the chemically thermal treatment. The produced barrier fully slows down the penetration of aluminium and oxygen into the basis and promotes the surface of the formation on the AlCoTi₂ compound, the microhardness of which due to dissolution of nitrogen, reaches 12.6 GPa. The maximum microhardness of the TiC layers is 31.0–35.5 GPa and of TiN layers 20–21.5 GPa. The stability of the nitrotitanoalitized polyhedral disposable carbide plates VK8 during cutting U8A steel grew by 10.5 times as compared with the initial stability.     

The effect of nanolayer thickness on the structure and properties of multilayer TiN/MoN coatings

The effect of nanolayer thickness on the structure and properties of nanocomposite multilayer TiN/MoN coatings is revealed. The multilayer (alternating) TiN/MoN coatings are prepared by the Arc-PVD method. The selected thickness of the nanolayers is 2, 10, 20, and 40 nm. The formation of two phases—TiN (fcc) and γ-Mo₂N—is found. The ratio of Ti and Mo concentrations varies with varying layer thickness. The maximum hardness value obtained for different thicknesses of the layers does not exceed 28–31 GPa. The stability of TiN/MoN during cutting and tribological tests is significantly higher than that of products with TiN coatings. The nanostructured multilayer coatings with layer thicknesses of 10 and 20 nm exhibit the lowest friction coefficient of 0.09–0.12.     

Tribological behavior at elevated temperature of multilayer TiCN/TiC/TiN hard coatings produced by chemical vapor deposition

Multilayer hard coatings of TiCN/TiC/TiN on high speed steel substrates were deposited using a chemical vapor deposition system. Evaluations of microstructure, wear morphology of coatings were characterized by scanning electron microscopy, and optical microscopy. Friction coefficient and wear rates of coatings were investigated using ball-on-disk tester sliding against a WC ball at a constant load of 20 N. Tribological behavior of the coatings at room and elevated temperature were discussed. Different changing tendency of friction coefficient were observed from ball-on-disc experiments. Results showed that the friction coefficient of coatings increased gradually to a highest value, then to a relatively constant value at room temperature dry sliding wear. The friction coefficient exhibited a reverse variation tendency at temperature of 550 °C. It got a higher value at the first sliding friction cycles. Then the value of friction coefficient decreased, suffered irregular oscillations and kept a relatively lower value with increasing sliding time. Reasons of the variation of friction coefficient with sliding time and wear mechanism were analyzed and discussed at room and elevated temperatures, respectively.     

X射线测量高速钢上不同厚度氮化钛涂层残余应力

采用多弧离子镀在AISIM2高速钢(HSS)上沉积了TiN硬涂层,试样中基体厚度为1mm,涂层厚度分别为3.0、5.0、7.0、9.0和11.0μm.应用X射线衍射(XRD)分析了TiN涂层中残余应力,测量了TiN(220)衍射晶面在五种不同倾斜角(Ψ=0°,20.7°,30°,37.8°和45°)下的X射线衍射峰.结果表明:在3～11μm涂层厚度范围内,TiN涂层中均表现出残余压应力且残余压应力值较大.TiN涂层中残余应力大致分布在-3.22～-2.04GPa之间,本征应力分布在-1.32～-0.14GPa,热应力约为-1.86～-1.75GPa.TiN涂层中残余应力值随涂层厚度变化是非线性增加的,随厚度增加表现出先增大后减小的变化趋势,多项式拟合后发现约在8.5μm厚时残余应力达到最大值.     

The effects of pre-implantation of steel substrates on the structural properties of TiN coatings

We have studied the effects of nitrogen pre-implantation of AISI C1045 steel substrates on the microstructure and microhardness of deposited TiN coatings. The substrates were implanted at 40 keV, to the fluences from 5 × 10¹⁶ to 5 × 10¹⁷ ions/cm², which was followed by deposition of 1.3-μm thick TiN coatings by reactive sputtering. Structural characterization of the samples was performed by standard and grazing incidence X-ray diffraction analysis, Rutherford backscattering spectroscopy and transmission electron microscopy. Microhardness was measured by the Vicker’s method. Nitrogen implantation up to 2 × 10¹⁷ ions/cm² induces the formation of Fe₂N phase in the near surface region of the substrates, which becomes more pronounced for higher fluences. Microstructure of the deposited TiN coatings shows a strong dependence on ion beam pre-treatment of the substrates. The layers grown on non-implanted substrates have a (200) TiN preferential orientation, and those grown on implanted substrates have (111) TiN preferential orientation. The change in preferred orientation of the layers is assigned to a developed surface topography of the substrates induced by ion implantation, and possible effects of distorted and altered crystalline structure at the surface. Ion implantation and deposition of TiN coatings induce an increase of microhardness of this low performance steel for more than eight times.     

界面梯度对TiN／不锈钢涂层应力的影响

气相沉积表面涂层在科学技术各领域得到广泛应用，然而，由于涂层与基体在化学和物理性质上的差异，使得涂层与基体在界面两侧产生结构和性能上的突变，影响了涂层功能的充分发挥。为此，采用多靶磁控溅射技术制备了具有梯度过渡层的ＴｉＮ／不多靶磁控溅射技术制备了具有梯度过渡层的ＴｉＮ／不锈钢涂层，并研究了梯度层对涂层内应力的影响。研究结果表明：采用多靶磁控溅射技术，分别控制各靶的功率，能够精确控制梯度层的成份变化     

Pulsed laser deposited alumino-silicate thin films and amorphous chalcogenide/alumino-silicate structures

Alumino-silicate coatings and structures formed from alumino-silicate and amorphous chalcogenide submicrometer layers were prepared by pulsed laser deposition. Fabricated thin films were characterized in terms of their structure, morphology, topography, chemical composition, optical properties, and basic anticorrosive functionality. Prepared coatings are amorphous, smooth, without micrometer-sized droplets, with chemical composition close to parent targets. Spectral dependencies of refractive indices and extinction coefficients were derived from variable angle spectroscopic ellipsometry data. Amorphous chalcogenide/alumino-silicate structures present large refractive index differences of individual layers (Δn ~ 1.2 at 1550 nm) which could be useful for optical systems working at infrared telecommunication band wavelengths. Basic anticorrosion data of alumino-silicate layers show promising anticorrosion behavior.     

Formation mechanisms of zinc,molybdenum, sulfur and phosphorus containing reaction layers on a diamond-like carbon (DLC) coating

Diamond-like carbon (DLC) coatings are nowadays successfully applied on industrial components like pistons, piston rings and bearings in lubricated tribological contacts due to friction and wear reducing effects. In contradiction thereto, todays lubricants and additives are designed for tribological steel/steel contacts, whereby the knowledge on tribochemical layer formation on steel surfaces is comprehensive in contrast to the physical-chemical interactions between diamond-like carbon coatings, lubricants and additives. Therefore the formation mechanisms of zinc, molybdenum, sulfur and phosphorus containing reaction layers on a zirconium modified diamond-like carbon coating a-C : H : Zr (ZrC_g) in lubricated tribological contacts were analyzed by means of pin-on-disc (PoD) tribometer by varying the distances from s = 200 m–3,000 m under boundary and mixed friction conditions at T = 90 °C and a contact pressure p = 1,300 MPa regarding the application of diamond-like carbon coatings on gears. The base lubricant poly-alpha-olefin (PAO) was formulated using the anti-wear (AW) and extreme pressure (EP) additive zinc dialkyldithiophosphate (ZnDTP) and the friction modifier (FM) additive molybdenum dialkyldithiophosphate (MoDTP). The chemical composition of the tribochemical reaction layers by means of and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) as well as for the thickness differ significantly by varying the additivation.     

A wear-resistant coating—Oxidized graded multilayer TiN/W coating

Combining sputtering technology using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™) with post heat treatment, a graded multilayer TiN/W coating, consisting of five layers, was synthesized and its outmost W layer was transformed to lubricious WO₃ successfully. The coatings were characterized by using GDOES, GXRD, a Rockwell C indentation tester, a nanoindentation tester, and a scratching tester. Wear behavior of coatings was evaluated by using a pin-on-disc tribometer. Through proper post heat treatment, the multilayer TiN/W coating, in spite of having a lower nano-hardness, showed good adhesion, much better wear performance and lower friction coefficient compared with the reference monolayer TiN coating.     

Silicon coating treatment to improve high temperature corrosion resistance of 9%Cr steels

Abstract

A silicon coating process is described which confers good protection on 9% Cr steels and alloys in CO₂ based atmospheres at high temperatures and pressures. The coatings are formed by decomposition of silane at temperatures above 720 K. Protective layers are typically up to 1 μm thick. The optimum coating conditions are discussed. The chemical state of the coatings has been investigated by X-ray photoelectron spectroscopy and has demonstrated the importance of avoiding silicon oxide formation during processing. Corrosion testing has been carried out for extended periods, up to 20 000 h, at temperatures between 753 and 853 K, in a simulated advanced gas cooled reactor gas at 4 MPa pressure. Benefit factors of up to 60 times have been measured for 9% Cr steels. Even higher values have been measured for 9Cr–Fe binary alloy on which a 1 μm coating was sufficient to eliminate significant oxidation over 19 000 h except at the specimen edges. The mechanism of protection is discussed. It is suggested that a silicon surface coating for protecting steels from high temperature corrosion has some advantages over adding silicon to the bulk metal.

MST/1090     

TiN/Ti多层膜调制比对摩擦磨损行为影响的研究

考察了TiN/Ti多层膜调制比对其摩擦磨损行为的影响. 采用磁过滤阴极弧沉积的方法制备了具有不同调制比的TiN/Ti多层膜, 用扫描电镜和透射电镜对其层状结构及子层结构进行了观察和分析. 用纳米压痕和SRV摩擦磨损试验的方法, 对多层膜进行了纳米硬度和弹性模量测试以及摩擦磨损实验. 结果表明, 所制备的TiN/Ti多层膜层状结构清晰, 与基底结合良好, 调制比对多层膜的硬度和磨损特性影响较大, 而对摩擦系数的影响却不明显. 结合实验结果, 讨论了硬度与弹性模量的比值(H/E值)对TiN/Ti多层膜耐磨性的影响.     

反应等离子喷涂TiN陶瓷涂层

采用气道型反应等离子喷涂技术,制备了TiN陶瓷涂层,通过XRD、SEM等手段对陶瓷涂层进行了相分析和横断面形貌分析。结果表明,陶瓷涂层主要由TiN相组成,并含有微量复杂成分的氧化物;TiN陶瓷涂层具有典型的层状组织结构,且层与层之间结合较好;显微压痕和断口显示TiN涂层的韧性较Al2O3涂层有明显提高。     

Hybrid plasma CVD of diamond-like carbon (DLC) at low temperatures

Diamond-like carbon coatings have been deposited onto various substrates at 100–150°C using a hybrid plasma assisted chemical vapour deposition technique activated by radio frequency at 13.56 MHz. The coatings have been characterized using a number of techniques including scanning electron microscopy, Raman spectroscopy, thermoanalysis and pin-on-disc wear testing. Results show the films to be diamond like, with the addition of nitrogen (prior to deposition) promoting the formation of crystallites. In addition the condition and type of substrate have been found to have a strong influence on the structural characteristics of the deposited diamond-like films. SEM analysis of diamond-like carbon coatings deposited onto metal matrix composite materials such as Si-Al MMC is reported. The hybrid CVD technology enabled films to be deposited evenly onto the porous MMC structure. Commercially manufactured drills, coated with DLC and titanium nitride (TiN), have been compared to examine their cutting wear resistance characteristics. This revised version was published online in November 2006 with corrections to the Cover Date.