恒定动能Si3N4颗粒重复冲击不同厚度TiN/Ti涂层损伤特征对比分析

目的 研究砂粒冲击航空发动机压气机叶片不同厚度的TiN/Ti硬质涂层损伤特征与机理。方法 采用Si3N4硬质球恒定动能垂直重复冲击试验方法,研究厚度对TiN/Ti涂层冲击损伤的影响。通过对比涂层动力学响应、能量吸收率、冲击坑点轮廓、H3/E2值和损伤形貌,分析不同厚度涂层的冲击坑点损伤特征。利用ABAQUS软件仿真获得垂直冲击下涂层的应力分布。结果 在调制比为9∶1的两层TiN/Ti涂层中,厚度为25 μm的涂层坑点直径最大,达到382.49 μm,比坑点直径最小的涂层（20 μm）大了24.8%;厚度为25 μm的涂层坑点最深,达到8.17 μm,比坑点最浅的涂层（15 μm）大了49.9%;厚度为5 μm涂层的接触力峰值最大,为161.4 N,比接触力峰值最小的涂层（20 μm）大了26.1%。随着涂层厚度的增加,涂层的抗冲击能力先增加后减小,厚度为20 μm的涂层抗冲击能力最好。冲击坑点损伤特征有三种：中心区与过渡区的疲劳剥落与疲劳磨损,边缘区的疲劳圆周裂纹与疲劳剥落,涂层/基体变形,其中,以剥落为主。结论 硬质层内的应力梯度和重复交变拉/压应力导致硬质层内产生疲劳圆周裂纹和疲劳剥落,硬质层与结合层界面处的高应力梯度导致产生层间疲劳剥落。     

钛合金表面百微米级Ti/TiN多层复合涂层性能研究

目的提高TiN硬质涂层的厚度及各项力学性能。方法采用等离子增强PVD技术在钛合金(TC4)基体表面制备多层复合Ti/TiN涂层,对涂层进行扫描电镜(SEM)分析,采用划痕法表征涂层的结合强度,用维氏显微硬度计测试涂层的显微硬度,利用销盘式摩擦磨损试验仪评价涂层的摩擦磨损性能。结果制备的多层复合Ti/TiN涂层厚度最高可达100μm,且未发生剥落等失效,结合强度相对于单层TiN提高了近3倍。由于Ti、TiN的多层复合调制作用,制备的Ti/TiN显微硬度测试表明复合涂层的显微硬度高达2700 HV0.025,同时,涂层在原有耐磨性能优良的基础上具备自润滑减摩作用,经过近20 000 m的磨损测试,复合涂层的摩擦系数低至0.25左右,且未完全失效。结论多层复合结构能够有效提高TiN硬质涂层的厚度,制备的Ti/TiN多层复合涂层的各项力学性能显著提高。     

多层结构对Ti/TiN涂层性能的影响

以TiN、TiAlN为主的过渡族金属氮化物硬质涂层以其较高的表面硬度、良好的耐磨以及抗高温氧化性能,被广泛应用于材料表面防护涂层。然而,涂层内部积聚的高内应力却容易易引发起涂层与基体的结合力问题。利用PVD技术很难在材料表面制备出厚度超过10微米的TiN或TiAlN涂层。多层复合结构能够有效控制涂层中的应力分布,从而使得其成为获得较厚硬质涂层的一种有效方法。本文在TC4合金以及Si（100）基体上利用等离子增强离子镀技术制备了具有不同复合层数的多层Ti/TiN涂层,并研究了复合层数对涂层力学性能的影响。结果表明,随着复合层数的增加,涂层的各项力学性能得到了显著强化。涂层的显微硬度高达2750HV,厚度大于50微米,且具有较好的韧性。涂层的韧性与显微硬度成正比例关系。同时,48层复合结构的Ti/TiN涂层具有低于0.35的摩擦系数以及最佳的抗磨损性能。然而,随着复合层数的进一步增加,涂层与基体的界面显著弱化了涂层的结合强度。     

多层结构对Ti/TiN涂层性能的影响（英文）

以TiN、TiAlN为主的过渡族金属氮化物硬质涂层以其较高的表面硬度、良好的耐磨以及抗高温氧化性能,被广泛应用于材料表面防护涂层。然而,涂层内部积聚的高内应力却容易引发涂层与基体的结合力问题。利用PVD技术很难在材料表面制备出厚度超过10μm的TiN或TiAlN涂层。多层复合结构能够有效控制涂层中的应力分布,从而使得其成为获得较厚硬质涂层的一种有效方法。本工作在TC4合金以及Si(100)基体上利用等离子增强离子镀技术制备了具有不同复合层数的多层Ti/TiN涂层,并研究了复合层数对涂层力学性能的影响。结果表明,随着复合层数的增加,涂层的各项力学性能得到了显著强化。涂层的显微硬度HV0.25高达27500 MPa,厚度大于50μm,且具有较好的韧性。涂层的韧性与显微硬度成正比例关系。同时,48层复合结构的Ti/TiN涂层具有低于0.35的摩擦系数以及最佳的抗磨损性能。然而,随着复合层数的进一步增加,涂层与基体的界面结合强度显著弱化。     

激光冲击强化前处理对TiN/Ti涂层/基体疲劳性能的影响

采用磁过滤阴极真空弧技术在TC4钛合金表面沉积抗冲蚀多层梯度TiN/Ti涂层,沉积前对基体进行激光冲击强化前处理。采用原子力显微镜、纳米压痕和划痕仪表征了试件的表面形貌、基本力学性能等,对试件的疲劳性能进行了考核,并分析了疲劳断口形貌。结果表明,LSP前处理在TC4表面形成了厚度约为300μm,具有高硬度和残余压应力的硬化层。TC4合金基体的平均疲劳强度为373.8 MPa,制备TiN/Ti涂层后试件的疲劳强度为363.7 MPa,较基体略有降低。增加LSP前处理后试件的疲劳强度为411.9 MPa,较TiN/Ti涂层试件提高13.3%,较无涂层试件提高10.2%。TiN/Ti涂层可以抑制表面上的裂纹萌生并减缓其扩展速率,但在拉伸过程中发生破碎而与基体发生剥离,裂纹抑制效果有限,且涂层的破裂促进了裂纹扩展。采用LSP前处理后,TC4表面形成的硬化层增加裂纹萌生难度,且提高的结合强度可降低裂纹扩展速率。     

TC4钛合金表面渗碳复合TiN(Ti)膜层的抗冲蚀性能研究

硬质膜层能够显著提高飞机发动机钛合金叶片的抗固体颗粒冲蚀性能,现有的软基体/硬膜层体系由于较高的脆性及界面不匹配性很容易被冲蚀,膜基界面极易发生脆性剥落。为了改善硬质膜层的抗冲蚀性能,结合辉光离子扩渗及等离子增强电弧离子镀技术,本文在TC4合金表面制备了具有梯度渗碳及TiN(Ti)膜层的复合渗镀层,并表征了结构对于复合渗镀层性能的影响。结果表明,相对于未强化的TC4基体表面单层TiN及12周期复合Ti/TiN膜层,复合渗镀层的显微硬度及膜基结合强度均同步得到了提高。冲蚀试验结果表明,TC4基体未渗碳前,表面单层TiN膜层呈现出脆性冲蚀开裂机制,12层复合Ti/TiN膜层由于多层复合结构的增韧效应,呈现出层状剥落及“冲蚀窝”损伤形貌。渗碳后,复合渗镀层的抗冲击韧性得到提高,单层TiN膜层在冲蚀条件下的膜基界面脆性开裂明显被抑制。渗碳复合12周期复合Ti/TiN结构的复合渗镀层具有最佳的抗固体颗粒冲蚀性能,表现出明显的韧性损伤机制,冲蚀失重率降低了十余倍。抗冲蚀性能的提高可归结于复合渗镀层较高的表面硬度、界面强度和强韧性匹配。     

TiN单层和TiN/Ti(C,N)多层涂层的结构和性能研究

借助XRD、SEM、纳米压痕和划痕仪研究了采用磁控溅射在硬质合金基体上沉积的TiN单层和TiN/Ti(C,N)多层涂层的组织结构和力学性能。研究表明:TiN与TiN/Ti(C,N)多层涂层的晶粒形貌均呈柱状晶结构,而TiN/Ti(C,N)多层涂层形成了TiN、Ti(C,N)交替的调制结构。由于界面强化作用,TiN/Ti(C,N)多层涂层表现出比TiN更高的硬度及与基体更好的结合力。     

TiN/TiAIN涂层的断裂韧性研究

采用多弧离子镀技术在Ti(C,N)基和WC基金属陶瓷基体上沉积了TiN/TiAlN涂层,利用维氏硬度计对涂层进行压痕试验;通过测试压痕周围的裂纹长度和数目,用裂纹密度β来评价涂层的断裂韧性.结果表明,Ti(C,N)基金属陶瓷基体上TiN/TiAlN涂层的裂纹密度为4558,比WC基金属陶瓷基体上涂层的裂纹密度低.TiN/TiAlN涂层的压痕形貌中,涂层没有剥落,只有沿压痕应力角径向显微裂纹和压痕四周的侧向显微裂纹,不同基体其压痕裂纹特点也不同.Ti(C,N)基金属陶瓷基体上涂层的径向裂纹非常短,并有裂纹偏转现象,侧向裂纹很长.WC基金属陶瓷基体上涂层的径向裂纹很长,非常平直,侧向裂纹很短.     

真空退火对TC4钛合金表面Ti/TiN多层复合涂层性能的影响

金属基体材料表面硬质膜层在服役过程中,残余应力在膜基界面以及膜层内部界面之间的积聚会导致膜层发生界面剥落失效。以TC4钛合金基体表面Ti/TiN多层复合膜层为研究对象,探讨真空退火对复合膜层结构及性能的影响,并表征退火前后复合膜层的界面划痕失效以及抗粒子冲蚀性能。结果表明,真空退火促进了膜层内部以及膜基界面两侧原子的热扩散,使得界面结构特征明显弱化。界面状态的改变使得复合膜层的表面显微硬度降低以及膜基结合强度提高。在划痕载荷作用下,复合膜层抵抗裂纹沿界面扩展的能力得到增强。真空退火有助于提高膜层的强韧性匹配,可有效抵抗小角度冲蚀粒子的犁削以及大角度粒子冲蚀下的疲劳,因此Ti/TiN多层复合膜层表现出较好的抗冲蚀性能。     

Ti/TiN/Zr/ZrN多层膜对1Cr17Ni2不锈钢疲劳性能的影响

采用真空阴极电弧沉积技术在1Cr17Ni2马氏体型不锈钢表面沉积Ti/TiN/Zr/ZrN多层膜。研究对比了在室温下膜层试样与基体试样的旋转弯曲疲劳强度、疲劳寿命和疲劳断裂机理。结果表明:在不锈钢基体上沉积厚度为11.7μm,硬度为3 220HV0.025,膜/基结合力为56N的Ti/TiN/Zr/ZrN多层膜后,其疲劳性能显著提高,膜层试样较基体试样的疲劳极限提高了约11.2%,当应力水平在540～650 MPa变化时,疲劳寿命增量变化范围为108%～246%;裂纹均起源于表面,在低应力水平下只有一个裂纹源,而高应力水平下有多个裂纹源;疲劳性能的提高主要是由于膜层能够弥补基体表面一定的缺陷,同时软硬交替的膜层结构有较强的抗裂纹扩展能力。     

航空发动机叶片 TiN / Ti 涂层基体冲蚀响应数值模拟

目的研究Ti N/Ti涂层结构变化对TC4钛合金基体冲击塑性应变的影响。方法采用有限元分析软件ABAQUS建立球形Al2O3颗粒冲击覆有Ti N/Ti涂层TC4基体的二维轴对称模型,分析涂层硬质层厚度、硬质层层数对基体在冲击过程中的等效塑性应变的影响规律。结果对于无涂层的基体,其冲击塑性应变仅发生在冲击的加载阶段,冲击塑性应变分为加载及卸载两个阶段,加载阶段基体的塑性应变由球形颗粒的冲击产生,卸载阶段基体的塑性应变由涂层硬质层的回弹产生。对于单层结构涂层,当硬质层厚度低于12μm时,随着硬质层厚度的增加,基体的塑性应变较大且呈振荡变化;当硬质层厚度超过12μm时,随着硬质层厚度的增加,基体的塑性应变减小。对于多层结构涂层,当硬质层的厚度不变,增加涂层硬质层层数使得基体的塑性应变减小。结论有限元可以模拟分析Ti N/Ti涂层结构对TC4钛合金冲蚀性能影响规律,优化Ti N/Ti抗冲蚀涂层的结构设计参数,对抗冲蚀涂层的结构设计及其进一步研究具有指导意义。     

Extremely hard,damage-tolerant ceramic coatings with functionally graded,periodically varying architecture

Functionally graded, multilayer coatings consisting of alternating TiN/TiSiN layers were synthesized in an attempt to overcome the innate brittleness of TiSiN nanocomposite coatings, whilst maintaining high hardness. These coatings exhibited key structural characteristics that are known to render many naturally occurring materials extremely hard and robust. Transmission electron microscopy revealed that shear sliding of columnar TiN grains played a vital role in controlling the inelastic deformation of these coatings, conferring a greater resistance to contact damage. Moreover, nanoindentation experiments showed that the multilayer coatings exhibited high hardness, attributed to the strong shear resistance offered by the hard TiSiN layers. A dependence of coating hardness upon indentation penetration depth (h_t) was found to be proportional to 1/√h_t, according to a mechanistically based model, from which the shear stress was determined. The energy dissipation during indentation was also quantified to show the critical role of the shear stress, regulated by the thickness of TiSiN layers, in resisting contact damage in the coatings. Finite-element models were constructed and the presence of transgranular cracks in the monolithic TiSiN coating was clarified based upon experimental observations. Furthermore, the simulations revealed that the transition of the dominant deformation mechanism from brittle transgranular cracking to intergranular shear sliding was controlled by the microstructural characteristics of the coatings. Enabled by the shear sliding, as well as periodic changes in elastic modulus, such a functionally graded multilayer structure was effective in lowering the magnitude and extent of stress concentrations, thereby extending the damage tolerance accessible to a ceramic coating.     

调制周期对TiN/Ti多层膜组织结构和结合力的影响

为了阐明调制周期对薄膜微观组织及薄膜与基体结合力的影响,采用反应磁控溅射在Ti6Al4V基板上交替沉积了Ti层及TiN层制备了TiN/Ti多层膜。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度仪和划痕仪测量分析了薄膜的晶体结构、微观组织、硬度以及薄膜与基体之间的结合力。研究结果表明:TiN/Ti多层膜中均存在TiN,Ti和Ti2N 3种相。TiN/Ti多层膜均以柱状晶方式生长,在调制周期较大(5层)时,TiN和Ti层的界面清晰;随着调制周期的减小(层数增加),TiN和Ti层的界面逐渐消失。与单层TiN薄膜相比,多层TiN/Ti薄膜的硬度显著提高;但随着薄膜层数的增加,多层TiN/Ti薄膜硬度略微降低。当调制周期为80nm(30层)时,薄膜与基体的结合力明显提高,达到73N。     

低模量Ti6Al4V表面Ti(Al/Pt)N薄膜强化改性

为解决硬质薄膜因与软基体硬度和模量差较大导致的薄膜失效问题,提高硬质薄膜在Ti6Al4V(TC4)钛合金基体上的适应性,使用掺杂氮化钛（TiN）陶瓷薄膜对低模量Ti6Al4V合金表面强化。采用热丝增强等离子体磁控溅射技术在Ti6Al4V合金表面制备Ti(Al/Pt)N薄膜：包括本征TiN、Al&Pt掺杂TiAlN和TiAl(Pt)N薄膜。采用扫描电子显微镜、X-射线衍射仪、纳米压痕仪、洛氏硬度计和摩擦磨损测试仪分别表征三种薄膜组织形貌、能谱分析、相结构和内应力、纳米硬度和模量及耐磨性。结果表明：Al元素掺杂使TiN薄膜柱状晶细化,截面形貌柱状晶更致密;同时微量Pt掺杂后,截面断口呈韧性撕裂。本征TiN和TiAlN薄膜衍射峰图谱呈现TiN(111)取向,TiAl(Pt)N薄膜的衍射峰呈TiN(200)主峰位。Al元素掺杂使TiN薄膜晶格畸变增多,内应力从-13 MPa增大到-115 MPa,导致膜-基结合力恶化,洛氏压痕和摩擦磨损实验中均出现薄膜剥落。Pt掺杂后薄膜内应力降低到-66 MPa,在洛氏压痕试验中TiAl(Pt)N薄膜与基体结合良好,仅有少许环形裂纹。摩擦磨损试验中本...     

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.     

Effect of micro-blasting on the tribological properties of TiN/MT-TiCN/Al2O3/TiCNO coatings deposited by CVD

The effect of micro-blasting on the tribological properties of TiN/MT-TiCN/Al₂O₃/TiCNO coatings was studied. The multilayer coatings were deposited on cemented carbides by chemical vapor deposition. The microstructure, mechanical and tribological properties were investigated using X-ray diffraction, scanning electron microscopy (SEM), nano-mechanical testing system, scratch tester and reciprocating tribometer. The results show that micro-blasting significantly reduces the surface roughness and converts the residual tensile stress of Ti(C,N,O) top-layer and Al₂O₃ layer into compressive stress. Affected by the residual compressive stress, the hardness and adhesion strength are increased. More importantly, the friction coefficient is decreased attributed to the decreased surface roughness and improved hardness. Also, the wear resistance of micro-blasted TiN/MT-TiCN/Al₂O₃/TiCNO is superior due to higher hardness of Ti(C,N,O) top-layer, Al₂O₃ layer and adhesion strength of coatings. Especially for the total sliding time of 2 h, the wear volume and wear rate of micro-blasted coatings are 69.4% of as-deposited coatings, because micro-blasting helps to increase the adhesion strength and micro-cracking resistance, which play important roles in the improvement of wear resistance. Micro-blasting has a positive effect on the friction and wear properties of TiN/MT-TiCN/Al₂O₃/TiCNO multilayer coatings since the adverse impact of top-layer thinning is offset.     

Finite element modelling of the thermo-mechanical behavior of coatings under extreme contact loading in dry machining

During metal cutting processes, intensive friction and high temperature generated at the tool chip interface affect the cutting zone of the tool, by inducing damage and wear. To improve the cutting tool's life, thin hard coatings, synthesized by physical or chemical vapor deposition (PVD or CVD) techniques, are often used as protective layers. In this work, numerical/theoretical analysis of dry machining has been performed to study the impact of different coating layers on the machining process. Four cases are considered: an uncoated tool made of tungsten carbide (WC-Co) and coated tungsten carbides in three different configurations. The first one is made of one layer namely TiN, the second one (hypothetical carbide insert) is composed of two layers (Al₂O₃ and TiN), and the last one has three layers (TiCN, Al₂O₃ and TiN). The workpiece material is an AISI 316L stainless steel. All cutting conditions are fixed in order to highlight the effect of coatings independently from others influencing parameters. The analysis has shown the impact of the different configurations of coatings on the temperature level inside the tool and on its surface, on the pressure and also on the cutting and feed forces.     

Tribological behavior and wear mechanisms of TiN/TiCN/TiN multilayer coatings

This work employs the PVD process to deposit coatings of single layer TiN, binary layer TiN/TiCN, multilayer TiN⇔⇔N, and sequenced TiN⇔CN⇔N multilayer coatings with variable individual TiN-layer and TiCN-layer thicknesses on tungsten carbide disks and inserts. Also investigated are the fracture mechanisms and the influence of sequence and thickness of these coatings on cylinder-on-disk, line-contact wear mode and ball-on-disk, point-contact wear mode through SRV reciprocating wear tests. Actual milling tests identify wear performance. Experimental results indicate that the coating with a total thickness of 7 Μm and layer sequence TiN/TiCN/TiN exhibits good wear resistance on SRV wear test and milling test. The thickest multilayer TiN/Ti/TiN coating, although having the highest hardness, has the worst wear resistance for all tests. No-tably zero-wear performance was observed for all coating disks under cutting fluid lubricated condition due to the transferred layers formed between the contact interface.