磁控溅射法制备TiB2涂层的研究进展

TiB2熔点高、硬度高、密度低、电阻率低、高温下化学稳定性好,是一种应用潜力巨大的涂层材料.磁控溅射法是一种重要的制备TiB2涂层的物理气相沉积方法,具有沉积温度低、基体可选择范围大的优点.分析和总结了偏压大小与极性、基体温度和气压等工艺参数对涂层沉积速率、显微结构(包括形貌、结晶度、织构和晶粒尺寸等)、性能(包括硬度、弹性模量、结合强度和摩擦学性能)和残余应力的影响,并概括了目前降低残余应力的途径.     

后处理工艺对BST薄膜残余应力的影响的分析

采用射频磁控溅射在Pt/Ti/SiO2/Si（100）衬底上制备了钛酸锶钡（BST）薄膜，利用气氛炉对薄膜进行晶化处理，晶化后薄膜的应力采用XRD表征。研究其残余应力随退火气氛、退火温度以及退火降温速率变化的趋势，通过对不同后处理工艺参数实验结果的分析，得到较优化的工艺参数，以制备较小残余应力的优质BST薄膜。     

TiB2和Ti-B-N涂层的性能对比研究

用磁控溅射法在1Cr18Ni9Ti不锈钢上沉积了TiB2和Ti-B-N涂层.用场发射电子扫描显微镜(FESEM)和小掠射角X射线衍射(GAXRD)研究了涂层的结构与形貌,并对涂层的显微硬度进行了检测分析.研究表明:通入N2后,Ti-B-N涂层变得更为光滑平整,涂层结构由纳米柱状晶转为非晶结构,显微硬度降低.在室温无润滑条件下,检测了涂层的耐磨性能,结果表明Ti-B-N涂层的摩擦系数低于TiB2涂层,但涂层的耐磨性并没有得到提高.     

喷丸处理对热障涂层中NiCrAlY结合层的影响

采用3kW射频电源在经真空电弧镀涂敷了NiCrAlY过渡层的涡轮和导向叶片上沉积ZrO2陶瓷层。对NiCrAlY涂层进行喷丸形变处理，研究了喷丸工艺对NiCrAlY涂层显微结构、相结构、残余应力和高温氧化性能的影响。结果表明：喷丸形变处理使涂层表面拉应力变为压应力；消除了NiCrAlY涂层气孔等缺陷，表面粗糙度Rz值由16．4μm减小到3．3μm；喷丸后涂层抗氧化性提高3倍．     

射频磁控溅射含氟羟基磷灰石涂层的研究

本文采用射频磁控溅射技术在钛合金(Ti6Al4V)基体上制备出含氟羟基磷灰石(FHA)生物涂层,探讨该涂层组织结构,不同氟含量和温度对涂层晶化程度的影响.利用扫描电镜(SEM)观察FHA生物涂层的表面形貌,采用X射线衍射仪(XRD)分析涂层相结构,利用能量分散谱仪(EDS)分析涂层的Ca/P比.结果表明,随着氟含量的增加可大大提高涂层的晶化程度,制备的FHA涂层致密、均匀.700℃晶化处理的涂层结晶度较高.     

偏压对磁控溅射制备Ni掺杂TiB2基涂层结构及力学性能的影响

采用双靶非反应磁控溅射,通过改变基底偏压,制备了一系列Ni掺杂TiB2基的涂层.通过X射线能谱仪确定其成分,利用X射线衍射、扫描电镜对涂层的结构进行分析,并通过纳米压痕、维氏压痕、划痕以及摩擦磨损分别对涂层的硬度、模量、断裂韧性、膜基结合力和摩擦学性能进行了表征.结果表明:此工艺下制备的TiB2-Ni涂层中均存在六方相的TiB2结构,并且生长结构非常致密,无明显的柱状生长结构,表面粗糙度低;硬度均大于40 GPa;涂层均具有较好的断裂韧性;且随着偏压增大断裂韧性和结合力都有所提高;同时所制备涂层摩擦系数均在0.5～0.6,磨损率在同一数量级.     

等离子喷涂纳米结构与传统结构热障涂层的残余应力对比研究

热障涂层的残余应力是影响其服役寿研究不多.在45钢基体上,用超音速火焰喷涂NiCocrAlY打底层,再用大气等离子喷涂ZrO2-8%(质量分数)Y2O3(8YSZ)工作层,制备了纳米结构与传统结构2种类型的热障涂层(TBC).采用SEM、XRD对这2种涂层的粉末及涂层进行了组织结构分析,用纳米压痕仪测得了2种涂层的弹性模量.用X射线衍射应力测试仪测得了2种涂层的表层残余应力.结果表明:喷涂工艺参数相同条件下,对于打底层及工作层的厚度均相同的2种涂层,纳米结构热障涂层的表层残余应力比传统结构热障涂层约低24.7%;相同打底层的纳米结构热障涂层表层残余应力随着陶瓷层厚度增加而增加,陶瓷层厚度在240 um以下时,表层为残余压应力;厚度超过300 um时,表层为残余拉应力.最后提出了相应的物理力学模型.     

再制造热喷涂层的残余应力与显微特征的对应关系

利用高效能超音速等离子喷涂(HEPS)、爆炸喷涂(DGS)和高速电孤喷涂(HVAS)三种热喷涂技术制备了不同厚度的Fe-Cr-B-Si和Fe-Cr-B-Si-Mo涂层,利用X射线应力测定仪测定了涂层表面残余应力,并得出表面残余应力与涂层厚度的关系曲线,进一步采用电解剥层法+X射线应力测定法研究了涂层应力沿厚度方向的分布...     

不同热喷涂技术制备铁基涂层摩擦学性能研究

采用高速电弧喷涂(HVAS)、超音速等离子喷涂(HEPJ)、爆炸喷涂(DGS)三种工艺喷涂技术,制备了铁基涂层.借助X射线应力测定仪、CETR摩擦磨损试验机、纳米测试仪等工具,考察了三种涂层表面残余应力场与(211)晶面半高宽,研究涂层在室温下的摩擦磨损性能.结果表明:爆炸喷涂(DGS)制备的铁基涂层相对于另外两种涂层具有更好的耐磨性,主要原因为爆炸喷涂(DGS)制备的同种材料的涂层表面表现为残余压应力,纳米硬度较大,晶粒较小,涂层致密.涂层表面的残余应力与涂层的摩擦性能有很好的对应关系,晶粒细化与涂层表面晶格畸变的增加可以有效地提高涂层的耐磨性能.     

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.     

纯钛表面激光硼化及其摩擦学性能

利用激光合金化技术在纯钛表面制备了TiB2合金化层。用XRD和SEM分析了合金化层的组成和组织结构。在CSM栓-盘摩擦磨损试验机上对钛及合金化层的摩擦磨损性能进行测试。结果表明:合金化层的主要成份是TiB2,合金化层表层的组织结构主要为柱状晶,合金化层的显微硬度达到1600HV0.1,TiB2合金化层的耐磨性能优于纯钛。     

含TiB2陶瓷相热喷涂涂层的研究进展

TiB2具有高耐磨、高耐腐蚀、耐高温、抗氧化等优异性能,但由于高脆性和材料制备的困难性,使其用作结构材料还很难.通过各种工艺制备含有TiB2陶瓷相的涂层既可充分发挥材料的优异特性,满足工件所需的耐磨耐高温耐腐蚀等性能,又节省了材料节约了成本.本研究介绍了先进陶瓷材料TiB2的主要结构性能以及目前制备TiB2涂层的主要方法,着重介绍了有关国内外热喷涂法制备含TiB2陶瓷相涂层的研究进展和成果,并对不同热喷涂工艺的特点与发展趋势做了分析和讨论,最后阐述了TiB2涂层的成功应用情况及其广阔的发展前景.     

电弧喷涂含TiB2金属陶瓷复合涂层的性能

为了减少磨损给生产所带来的经济损失,利用电弧喷涂含TiB2的粉芯线材来制备含TiB2陶瓷的涂层,并对涂层的结合强度、硬度、抗热震性和耐磨粒磨损性能等进行了测试,利用金相显微镜、X-射线衍射仪、扫描电子显微镜等对涂层进行测试分析,研究涂层磨损机理.研究结果表明,涂层结合强度达到49MPa,显微硬度达887HV,具有良好的抗热震性能,耐磨粒磨损性能比基体Q235钢提高了4.5倍.研制的涂层具有极大的实际应用和推广价值.     

Residual stress, Young''s modulus and fracture stress of hot flame deposited diamond

Chemical vapour deposition (CVD) diamond coatings deposited on various substrates usually contain residual stresses. Since the residual stress affects the adhesion of the coating to the substrate, as well as the performance of the coating/substrate composite in many technical applications it is of importance to study the magnitude of these stresses.

In the present study the hot flame method was used to deposit diamond coatings on cemented carbide inserts by scanning the surface with a nine flame nozzle. By varying the oxygen to acetylene flow ratio and the deposition time coatings of different qualities and thicknesses were obtained. The residual strain/stress of the coatings was measured by three different methods: X-ray diffraction using the sin² (Ψ) method, Raman spectroscopy and disc deflection measurements. To extract the residual stress from the strain data the Young's modulus was obtained from bending tests of diamond cantilever beams manufactured from free standing diamond films. The latter technique was also used to determine the fracture stress of the diamond films.

All deposited coatings displayed a residual compressive strain/stress state. The residual strain in the diamond coatings did not vary with coating thickness (1.5 μm to 20 μm) but was found to increase from −1.8 × 10⁻³ to −2.2 × 10⁻³ with decreasing diamond quality. The compressive residual stress was found to decrease from −2 GPa to −1.3 GPa with decreasing diamond quality. This is mainly due to a decrease in Young's modulus (from 1.1 TPa to 0.6 TPa) with decreasing diamond quality. Also the fracture stress was found to decrease (from 1.8 GPa to 0.8 GPa) with decreasing diamond quality. The three methods used for measuring the stress state in the coatings, X-ray diffraction, Raman spectroscopy and deflection measurement, all give the same result. The deflection technique has the advantage that no information about the elastic properties of the coating is needed, whereas Raman spectroscopy has the best lateral resolution (≈5 μm) and is the fastest method (≈5 min).     

Deposition of silicon carbide coatings on titanium alloy with a low pressure R.F. plasma

A low pressure r.f. plasma was applied to deposit SiC coatings onto Ti6A14V substrates. The coatings were deposited onto substrates at temperatures of 140–390°C from a gas mixture of tetramethylsilane (TMS), argon and hydrogen. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy were employed to identify and to characterize the coatings obtained. It was found that the coatings were hexagonal α-SiC of type III. The coating thickness approximately follows a parabolic time law. A maximum rate of deposition was observed in the pressure range 5–6 mbar. The rate of deposition increases with concentration of TMS up to 0.05% and remains approximately constant up to 0.12%     

The effects of drying, aging and curing on an organic - inorganic coating

The effects of drying, aging and curing on an organic - inorganic coating deposited on float glass substrates were analyzed. Methyltrimethoxysilane was used to immobilize parts of the network connections and silica particles were used as seeds for the nucleation of the gel structure. The coating was produced under acidic conditions to enhance the hydrolysis reaction. The coatings were deposited using a spin-coating technique. The dependence of the elastic modulus, hardness, fracture toughness and residual stress obtained by indentation on the preparation conditions is reported. In addition results obtained by X-ray diffraction (XRD), Atomic Force Microscopy (AFM), X-ray Photon Spectroscopy (XPS) and Infrared-Spectroscopy are analyzed.     

Prediction of residual stresses in thermally sprayed steel coatings considering the phase transformation effect

The present study is aimed to propose an elastoplastic bilayer model for prediction of residual stresses in thermally sprayed coatings, in which the effect caused by martensite phase transformation for steel coating materials was taken into account. Closed-form solutions of the curvature and stresses within the substrate and coating are obtained for the plastically deformed structures. Applications of the model for prediction of the twin-wire electric arc sprayed high carbon steel coatings were investigated subsequently. In the application case that a thin coating layer deposited with varying temperatures, the martensite phase transformation has a significant effect on the residual stress, e.g. a lower deposition temperature leads to more amount of martensite transformation and then to a lower level of final stress. The model was also used to predict the stress distribution of high carbon steel coating after quenching heat treatment, and the calculation results were compared with the X-ray residual stress measurements. It is found that the residual stresses on the coating surface obtained from the analytical model are closed to that obtained from the experiments.     

Determination of residual stresses in cathodic arc coatings by means of the parallel beam glancing X-ray diffraction technique

A method based on the parallel beam glancing X-ray diffraction geometry has been applied to the measurement of the residual stresses present in cathodic arc plasma (Al_0.66Ti_0.34)N coatings deposited on hardmetal substrates. This procedure avoids the problems associated to the strong overlapping between the diffraction peaks of the coating and the substrate. The method has been validated by comparison with the results obtained with sin²ψ technique on other combinations of coatings and substrates in which no important overlapping occurs (i.e. (Al_0.66Ti_0.34)N on steel and TiN either on steel or on hardmetal substrates). The elastic moduli of the different coatings, required for the calculation of the residual stresses, have been obtained from nanoindentation experiments.     

A comparative study of the mechanical strength of chemical vapor-deposited diamond and physical vapor-deposited hard coatings

Four mechanical parameters of physical vapor-deposited (PVD) hard coatings were obtained, which were the residual strain, Young's modulus, film toughness, and interface toughness, concerning titanium aluminum nitride (TiAlN) and titanium nitride (TiN) coatings deposited on WC-Co substrates. The results were quantitatively compared with the author's previous trials for the case of chemical vapor-deposited (CVD) diamond coatings. Due to the significant difference in the mechanical properties between PVD hard coatings and CVD diamond coatings, it was necessary to develop new experimental techniques, which could properly evaluate those parameters for the case of PVD hard coatings. As a conclusion, film toughness of PVD hard coatings was surprisingly brittle. It was an order of magnitude smaller than that of CVD diamond coatings. In contrast, no significant difference was found in interface toughness between these different kinds of coatings. Concerning the residual strain, TiN had far larger level than the other two. These differences in mechanical properties were further discussed in relation to the difference in their wear behavior.