Erosion performance and characterization of nanolayer (Ti,Cr)N hard coatings for gas turbine engine compressor blade applications

(Ti,Cr)N nanolayer coatings were deposited on Ti–6Al–4V, 17-4PH and Inconel 718 substrates using cathodic arc physical vapor deposition for improved erosion and corrosion resistance. Coating corrosion performance was highly dependent on the coating thickness and packing factors and correlated with increased chromium content within the (Ti,Cr)N nanolayer coatings. The change in cathode current predominantly affected coating thickness and the bias affected the packing factor. Erosion tests of the coated and uncoated substrates at both 30° and 90° erodent impingement angles were conducted using angular aluminum oxide media at particle velocities up to 145 m/s. Chromium evaporator current and substrate bias were varied to change film stoichiometry and microstructure for erosion performance evaluation. When chromium evaporator current was varied, the increase in chromium content led to an increase in binary CrN phase volume and a decrease in TiN phase volume. The increase in CrN phase volume decreased both hardness and erosion performance at both impingement angles. Lower bias values resulted in better erosion performance. At 30° erodent impingement, all coated samples outperformed the uncoated substrate; whereas, for 90° impingement, only coatings deposited at low bias values (? 25 V, ? 50 V, and ? 100 V) and high Ti:Cr ratios (> 2.4) outperformed the uncoated substrate. The primary coating failure mechanism was microchipping.     

High-Temperature Oxidation Behavior of (Ti,Cr)N Coating Deposited on 4Cr13 Stainless Steel by Multi-arc Ion Plating

在4Cr13不锈钢表面进行多弧离子镀沉积(Ti,Cr)N涂层,研究不同Cr含量的(Ti1-xCrx)N(x=0.28,0.56,0.73)复合薄膜在700℃的高温氧化行为。考察了薄膜氧化后的表面形貌、成分等。用热重法(TG)与差示扫描量热分析法(DSC)分析(Ti,Cr)N薄膜的加热氧化情况,并与TiN薄膜进行对比。结果表明:随着铬靶弧电流(ICr)的提高,(Ti1-xCrx)N薄膜中的Cr含量增加,Cr含量与ICr/ITi存在着线性关系;Cr含量越高,(Ti1-xCrx)N薄膜的高温抗氧化性能越好;(Ti1-xCrx)N薄膜的氧化热力学温度均高于TiN薄膜,表明Cr的加入明显提高了薄膜的氧化热力学温度。     

Wear, erosion and corrosion resistance of CrTiAlN coating deposited by magnetron sputtering

A nanolayered CrTiAlN coating, which was deposited on Ti6Al4V substrate using unbalanced magnetron sputtering technique, was tested to evaluate its performances against wear, erosion and corrosion. The coating, with a higher hardness compared to CrN, demonstrates significantly higher dry sliding wear resistance than CrN and TiN coatings. Different from the brittle TiN coating, the CrTiAlN coating has a maximum erosion rate at an impingement angle of 45° and shows better erosion resistance than TiN coating at 90°. The CrTiAlN coated Ti6Al4V, when tested in 3.5% NaCl aqueous solution, shows a markedly more noble corrosion potential in comparison with the uncoated Ti6Al4V substrate. Furthermore, it demonstrates a wide passive region with a low current density. All these properties make the CrTiAlN coating a good candidate for a variety of industrial applications.     

Microstructural characterization of binary and ternary hard coating systems for wear protection. Part I: PVD coatings

Different wear-resistant coatings produced by physical vapour deposition (PVD) were characterized with the aid of cross-sectional transmission electron microscopy (XTEM). All coating systems were optimized by the producers and exhibited good properties with respect to their special applications. The microstructure, texture and chemical composition of binary and ternary systems produced by the arc process [TiN, CrN, Cr₂N (Ti, Cr)N on steel substrates] and magnetron sputtering process [TiN, CrN on steel substrates, (Ti, Al)N on Si-substrate] were investigated. All coatings had a more or less columnar microstructure, which was interrupted by interlayers in some cases. Whereas arc coatings always did show some kind of substrate modification, the latter was not observed after magnetron sputtering. Electron diffraction normally revealed a mono-phase fcc structure, except at sites very near to the interface. Only for the systems Cr–N and (Ti, Cr)–N were different additional phases observed at low nitrogen partial pressures.     

电弧离子镀CrTiN涂层的结构及耐腐蚀性能

采用电弧离子镀技术在模具钢H13表面沉积Cr_xTi_1-xN涂层,系统研究了不同Cr/Ti原子比对CrTiN合金化涂层结构、力学性能以及耐腐蚀性能的影响。结果表明:通过改变分离靶弧流实现CrTiN涂层中Cr/Ti原子比的有效调控,所制备的CrTiN涂层主要由面心立方结构(Cr, Ti)N和CrN组成,随着Cr/Ti原子比从1.1增加至1.8,涂层相结构由随机取向向(111)晶面优先生长转变。CrTiN合金化涂层显微硬度较CrN涂层得到明显提升,并随着固溶引起的晶格畸变程度变化而具有一个极大值。通过电化学阻抗谱和动电位极化曲线分析,当Cr/Ti原子比为1.4时,致密的Cr_0.59Ti_0.41N涂层具有最佳的耐腐蚀性能。     

多弧离子镀Ti-Al-Zr-Cr-N系双层膜的结构与力学性能

采用多弧离子镀技术和Ti-Al-Zr合金靶及Cr单质靶,在WC-8%Co硬质合金基体上制备了(Ti,Al,Zr)N/(Ti,Al,Zr,Cr)N和Cr N/(Ti,Al,Zr,Cr)N 2种四元双层氮化物膜。利用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析2种双层膜的微观组织、成分和结构;利用划痕仪和显微硬度计对比2种双层膜的力学性能。结果表明,获得的2种双层膜均具有B1-NaCl型的TiN面心立方结构;双层膜的组织均是典型的柱状晶结构;沉积偏压为–50~–200 V时,双层膜的力学性能均优于(Ti,Al,Zr,Cr)N单层膜,并与Ti-Al-Zr-Cr-N系梯度膜的力学性能相当,同时(Ti,Al,Zr)N/(Ti,Al,Zr,Cr)N双层膜可获得更高的硬度(HV_(0.01)最高值为41 GPa),而CrN/(Ti,Al,Zr,Cr)N双层膜可获得更强的膜层与基体间结合力(所有值均大于200 N)。     

Erosion wear of CrN,TiN, CrAlN,and TiAlN PVD nitride coatings

Four nitride coatings (CrN, ZrN, CrAlN, and TiAlN) were deposited on YT15 cemented carbide by cathode arc-evaporation technique. Microstructural and fundamental properties of these nitride coatings were examined. Erosion wear tests were carried out, the erosion wear of these nitride coatings caused by abrasive particle impact was compared by determining the wear depth and the erosion rates of the coatings. The wear surface features were examined by scanning electron microscopy. Results showed that the coatings with Al (CrAlN and TiAlN) exhibited higher erosion wear resistance over those without Al (CrN and TiN). The H³/E² of the coating seemed to play an important role with respect to its erosion wear in erosion tests. AlTiN and CrAlN coatings being with high H³/E² exhibited lower erosion rates, while CrN coating with low H³/E² showed higher erosion rates under the same test conditions. Analysis of eroded surface of the coatings demonstrated that the TiN and CrN coatings exhibited a typical brittle fracture induced removal process, while AlTiN and CrAlN coatings showed mainly micro cutting and cycle fatigue fracture of material removal mode.     

离子注入对TC4钛合金TiN/Ti涂层结合力和抗砂尘冲蚀性能的影响

目的通过离子注入提高TiN/Ti涂层的结合力和抗冲蚀性能。方法先采用金属蒸气真空弧(MEVVA)离子源在TC4基体上分别注入四种离子(Mo、Ti、Nb、Co),再用磁过滤真空阴极弧(FCVA)技术制备TiN/Ti涂层。采用非球面测量仪、AFM、XRD和纳米压痕仪,对四种离子注入的TC4基体表面粗糙度、表面形貌、物相结构、纳米硬度和弹性模量进行表征,采用划痕仪测量涂层的结合力,采用涂层冲蚀考核平台对不同试样进行砂尘冲蚀性能试验。结果经过Mo、Ti、Nb离子注入的TiN/Ti涂层的结合力和抗冲蚀性能都有提高,其中Mo离子注入的TiN/Ti涂层的结合力达71 N、耐冲蚀时间为80 min,与未离子注入涂层相比,分别增加31.5%和77.8%,而平均冲蚀率降低39.5%,仅为0.0078mg/g。Co离子注入的TiN/Ti涂层的结合力仅为40 N,平均冲蚀率增大了19.0%,达0.0433 mg/g,其抗砂尘冲蚀性能明显下降。结论离子注入涂层的抗砂尘冲蚀性能与结合力密切相关,随着结合力的增大,TiN/Ti涂层的平均冲蚀率减小,其耐冲蚀时间增加,选择合适的离子注入可提高TiN/Ti涂层的抗冲蚀性能。     

Microstructure and defect characterization at interfaces in TiN/CrN multilayer coatings

Microstructures of TiN/CrN multilayer coatings deposited on austenite steel (Cr Ni 18 8) by pulsed laser deposition (PLD) are characterized using transmission electron microscopy while their mechanical properties were assessed in a ball-on-disk test. All coatings have the same total thickness of about 1 μm. The individual layers show a highly defective columnar structure, which is characterized by conventional electron microscopy (TEM) as well as by high resolution TEM. These techniques, combined with measurements of the local chemical composition through EDS prove that PLD allows to produce fully separated CrN and TiN layers. The friction, and consequently the wear, are lowered by increasing the total number of layers in the coating.     

Ti靶电流对CrTiAlN镀层组织结构及硬度的影响

利用磁控溅射技术在高速钢和单晶硅基体上沉积CrTiAlN梯度镀层,研究Ti靶电流对CrTiAlN镀层组织、相结构及硬度的影响.利用EDS、XRD和SEM分析镀层的成分、相结构及形貌,采用显微硬度计测量镀层的硬度.结果表明:随着Ti靶电流的增大,镀层中的Ti原子逐渐置换CrN中的Cr原子形成Cr-Ti-N体系,同时出现少量的TiN相;镀层生长的择优取向由(111)晶面逐渐转变为(200)晶面;镀层柱状晶的结构更为致密,其表面形貌由三棱锥结构逐步变为胞状结构;随Ti靶电流的增大,镀层硬度逐渐由1267HV升至1876HV.     

Evaluation of the protective properties of multilayer coatings for steam turbine blades

The results of investigation of the protective properties of multilayer ion-plasma coatings relative to the conditions of their exploitation on steam turbines are described. It was established that the protection properties of coatings on 20X13 steel in an aggressive NaCl environment of various concentrations increase according to the sequence [Cr + (Cr,Ti)N]₁₀ < (Ti + TiN)₁₀ < (Cr + CrN)₁₀. It was also found that a breach in the coating integrity can lead to the appearance of macrogalvanic couples. Their activity considerably increases (by 4–5 times) during the mechanical passivation of the surface under the conditions of drop-collision erosive wear. The greatest values of the EMF in stationary conditions are generated between the 20X13 steel and Ti + TiN coating.     

Pulsed DC plasma enhanced chemical vapor deposited TiN/Ti(C,N) multilayer coatings

1　ＩＮＴＲＯＤＵＣＴＩＯＮＶａｒｉｏｕｓｃｏａｔｉｎｇｓｄｅｐｏｓｉｔｉｏｎｔｅｃｈｎｉｑｕｅｓ ,ｓｕｃｈａｓＰＶＤ ,ＣＶＤ ,ＰＣＶＤ ,ＩＢＥＤａｎｄＰＳＩＩｈａｖｅｂｅｅｎｕｓｅｄｔｏｉｍｐｒｏｖｅｔｈｅｗｅａｒ ｒｅｓｉｓｔａｎｃｅ ,ｃｏｒｒｏｓｉｏｎ ｒｅｓｉｓｔａｎｃｅａｓｗｅｌｌａｓｅｌｅｖａｔｅｄａｎｔｉ ｏｘｉｄａｔｉｏｎｂｅｈａｖｉｏｒｏｆｓｕｒｆａｃｅｏｆｓｔｅｅｌｓ ,ｆｏｒｉｎｓｔａｎｃｅ ,ｃｕｔｔｉｎｇｔｏｏｌｏｒｄｉｅｓｔｅｅｌｓａｎｄｎｏｎ ｆｅｒｒｏｕｓｍｅｔａｌｓｉｎ…     

TC4钛合金表面涂层改性:CrN素多层

目的 提高TC4钛合金的硬度和耐磨损性,改善CrN硬质涂层与TC4钛合金的适应性.方法 采用等离子体增强磁控溅射系统,通过调节热丝放电电流,在TC4钛合金基体表面沉积疏密CrN单层和素多层涂层.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、纳米压痕仪、洛氏压痕仪、摩擦磨损仪以及台阶仪,表征涂层形貌、成分、物相及性能.采用动电位极化法表征涂层的耐腐蚀性.结果 当热丝放电电流为较低的4 A×4时,沉积的CrN单层涂层为具有针孔、孔洞等缺陷的疏松结构,8 A×4沉积的CrN单层涂层具有致密结构,周期性调节热丝放电电流则获得疏密交替的CrN素多层涂层.CrN涂层均由单一面心立方结构的CrN相组成,疏松CrN单层涂层的衍射晶面为(111)、(200)、(220)及(222),致密CrN单层涂层沿(111)晶面择优生长,随着疏密子层调制比的增大,CrN素多层涂层的(111)衍射峰不断增强.疏松CrN单层涂层的最小H和最大E分别为13.0 GPa和207.5 GPa,调制比为1:4的疏密CrN素多层涂层的最小H和最大E分别为17.0 GPa和257.4 GP.在1470 N载荷下洛式压痕法表明,致密CrN单层涂层的结合强度最低,等级为HF5,其余涂层均为HF1—HF4.CrN涂层的自腐蚀电位较TC4钛合金均发生了正移.结论 CrN硬质涂层可以有效提高TC4钛合金的硬度和耐磨损性,表面得到明显强化.周期性调节等离子体密度所沉积的疏密CrN素多层涂层与单层相比,涂层性能明显改善.     

Thermal stability behaviors of Cr(N,O)/CrN double-layered coatings by TGA/DTA analysis

In this study, Cr(N,O)/CrN double-layered coatings were synthesized using the cathodic arc deposition (CAD) process. CrN film was first deposited onto a substrate as an interlayer to ensure better adhesion, and Cr(N,O) film was subsequently deposited on top of the CrN layer as the surface layer. Variation in the Cr(N,O) coating composition was achieved through changing the O₂/N₂ flow ratio during the last stage of processing. Phase structure, chemical composition, and morphology of the resulting coatings were analyzed and observed using the X-ray diffractometer, Auger electron spectrometer and SEM. In addition, oxidation behavior of the coatings was investigated using TGA/DTA methods. The tests were carried out by increasing temperature up to 1000 °C in ambient air. With the introduction of oxygen gas during the CAD process, a superficial layer was produced in the Cr(N,O) constituent containing CrN and Cr₂O₃ phases. The formation of the oxide phase attributed to the reaction of chromium and oxygen was more favorable than that of chromium and nitrogen. The results also showed that Cr(N,O)/CrN double-layered coatings exhibited superior oxidation resistance at elevated temperature than that of CrN single-layer coated specimen (870 °C vs. 750 °C).     

Triode plasma nitriding and PVD coating: A successful pre-treatment combination to improve the wear resistance of DLC coatings on Ti6Al4V alloy

Diamond-like carbon (DLC) coatings have found great applicability in the automotive industry because of their low friction coefficient and high wear resistance. Nevertheless, their tribological performance can be greatly reduced on soft substrates such as titanium alloys. The hard DLC coating cannot usually follow elastic and plastic deformation of the substrate without failing. In order to overcome this property mismatch between hard coating and soft substrate, triode plasma nitriding was applied as a pre-treatment to improve the mechanical properties of the Ti6Al4V alloy and further enhance the load support for the DLC coating. DLC and multilayered TiN/DLC, CrN/DLC CrAlN/DLC coatings were deposited onto “standard” and plasma nitrided Ti6Al4V substrates. Triode plasma nitriding increased the load-bearing capacity of the coating/substrate system, as higher critical adhesion loads were recorded for DLC coatings on plasma nitrided Ti6Al4V substrates. This treatment also reduced the wear rate of the DLC coating/substrate. Further load support and lower wear rates were achieved by using TiN, CrN and CrAlN as intermediate layers on plasma nitrided Ti6Al4V substrates.     

Cr基及其化合物过渡层对TiCN涂层性能的影响

为研究过渡层材料及结构对TiCN涂层性能的影响,设计3种Cr基及其化合物过渡层,利用多弧离子镀技术制备TiCN涂层。膜系分别为Cr/TiCN、Cr/CrN/TiCN和Cr/CrN/CrCN/TiCN。利用SEM、XRD、纳米压痕仪、划痕仪、摩擦磨损试验机和球磨仪对涂层的微观结构和性能进行表征。结果表明:随着过渡层由单层Cr依次加入CrN和CrCN,涂层原有的柱状晶生长被抑制并最终消除。与具有Ti过渡层的TiCN相比,涂层不再具有明显择优取向,(111)峰强度大大减弱而(200)峰发生宽化。具有CrN和CrCN过渡层的样品硬度和附着力明显高于以单层Cr为过渡层的样品,Cr/CrN/CrCN/TiCN膜系硬度和附着力最高,分别为(30.11±0.34)GPa和(37.21±0.46)N。摩擦磨损试验结果表明:CrCN过渡层的引入显著提升了涂层耐磨性,其对应样品摩擦因数最低,达到0.111,并在球磨测试中表现稳定,而其它膜系均出现不同程度的磨损形貌。     

Characteristics and machining applications of Ti(Y)N coatings

The Ti(Y)N coatings were successfully deposited onto 18-8 stainless steel substrates by the hollow cathode discharge ion-plating method. The influence of the rare-earth element yttrium on the TiN coating properties was studied. The results show that the adhesion of the coating to the substrate were evidently enhanced by adding a small amount (0.2 wt.%) of the rare-earth element yttrium, showing a critical load of about 390 g which is much higher than that (230 g) of the TiN coating/substrate. Investigation on the corrosion resistance of the Ti(Y)N coating and the TiN coating was performed in 0.5 N Na₂SO₄ + 0.1 N H₂SO₄ + 0.1 N NaCl corrosion media by means of an electrochemical potentiodynamic polarization. The Ti(Y)N coating exhibited much better corrosion resistance than the TiN coating, whose passivity maintaining current is about one order in magnitude smaller than that of the TiN coating.The Ti(Y)N coatings deposited on some HSS-based tools were presented and compared with the TiN coating. The service lifetime of Ti(Y)N coated tools is approximately 36% higher (on the pinion shape cutters) and about 50% higher (on punch side pin) compared to that of TiN coated. The Ti(Y)N coatings showed such excellent performance. It is attributed to that the transition area of Ti(Y)N/substrate consisted of three sublayers which revealed a gradual change of phase structure and composition, so that the adhesion of the coating/substrate was evidently enhanced. Moreover, Ti(Y)N coating showed a preferred orientation with (111) plane which is favorable to improve wear resistance and corrosion resistance of the coating.     

Effects of nitrogen pressure and pulse bias voltage on the properties of Cr-N coatings deposited by arc ion plating

Cr-N coatings were deposited on 1Cr18Ni9Ti stainless steel in the pure N₂ atmosphere by arc ion plating (AIP). The relationships between deposition parameters and coating properties were investigated. X-ray diffraction showed a phase transformation from CrN + Cr₂N + Cr → CrN + Cr → CrN and the CrN preferred orientation changed from (200) to (220) as N₂ pressure increased. Increasing bias voltage led to CrN preferred orientation changed from (200) to (220) and the formation of Cr₂N. XPS results indicated that chemical composition of the coatings changed as N₂ pressure increased but it changed little with bias voltage. The lower melting point of chromium nitride formed on target surface induced the increase of macroparticles and deposition rate with increasing N₂ pressure; and bias voltage had an obvious effect on reducing macroparticles of the Cr-N coatings. Residual stresses were measured by substrate curvature technique, and the changing tendency coincided with the microhardness of the coatings.     

Influence of interlayers on corrosion resistance of diamond-like carbon coating on magnesium alloy

Diamond-like carbon coating (DLC) was deposited on AZ31 magnesium alloy by ion beam deposition technique in this study. A columnar Cr layer with a (110) preferred texture and a columnar CrN layer with a (111) preferred texture were applied as interlayers in the DLC coating/AZ31 substrate systems. The addition of these interlayers improved the adhesion between coating and substrate effectively, but did not enhance the corrosion resistance of the DLC/AZ31 systems due to the formation of galvanic cell between substrate and interlayer in the region of through-thickness defects in 3.5 wt.% NaCl solution. In addition, the effect of bias voltage on the corrosion resistance of CrN/Cr coatings on magnesium alloys was investigated. Although the application of bias voltage induced the coating denser, it was still difficult for CrN/Cr coating to reduce the corrosion current density of AZ31 due to the large difference between coating and substrate in galvanic series.     

TiN, TiN gradient and Ti/TiN multi-layer protective coatings on Uranium

Single-layer TiN, gradient TiN and multi-layer Ti/TiN coating were deposited on silicon and uranium substrates by means of arc ion plating technique. The main phase in the single-layer TiN coating was TiN with a (111) preferred orientation. Ti and TiN were observed in the TiN gradient coating and Ti/TiN multi-layer coatings. The single-layer TiN coating has demonstrated the best wear resistance among the three coatings. Compared with the bare U substrate, the corrosion potential E_corr of the multi-layer Ti/TiN coatings is increased by 580 mV, and the corrosion current density I_corr is decreased at least by two orders of magnitude. The multi-layer Ti/TiN coatings possessed the highest corrosion resistance among the three coating in a 0.5 μg/g Cl⁻ solution.