射频磁控溅射法制备TiB2涂层及其性能分析

利用射频磁控溅射技术在硅和钢片上沉积了TiB2涂层.采用场发射电子扫描显微镜(FESEM),小掠射角x射线衍射(GAXRD)及X射线光电子能谱(XPS)分别研究了涂层的横截面形貌,晶体结构以及涂层中的元素和化学状态.同时,对涂层的显微硬度和残余应力进行了表征.结果表明, 利用射频磁控溅射法制备的TiB2涂层平整光滑,结构致密,沿[001]晶向择优生长,具有纳米晶结构,硬度显著提高,而且残余压应力较低.     

物理气相沉积TiAlN涂层的研究进展

概述了物理气相沉积TiAlN涂层的研究现状及发展趋势,详细分析了制备方法、Al含量、N2流量、基体偏压、温度以及其他元素对TiAlN涂层的涂层结构、硬度、高温抗氧化性和耐腐蚀性等性能的影响.目前制备的TiAlN涂层存在残余应力较大、表面液滴数量较多和涂层致密度差等问题.为进一步促进TiAlN涂层的应用,今后还需探索该涂层的制备方法,优化其制备工艺.多元纳米复合涂层和超点阵多层涂层是两个具有潜力的发展方向.     

MoS2软涂层刀具的基体材料优选及涂层制备

以常见的几种高速钢和硬质合金为基体材料，运用有限元软件分析了基体表面MoS2软涂层的残余热应力。结果表明：高速钢表面涂层的最大残余热应力小于硬质合金表面涂层的残余热应力；涂层与基体之间弹性模量和热膨胀系数等参数及沉积温度的差异是影响涂层残余热应力大小的主要因素。采用中频磁控溅射加离子束辅助沉积工艺制备了两种MoS2软涂层刀具并对其性能进行了测试，分析结果符合有限元计算的结论。     

黏结相含量对超音速火焰喷涂TiB_2-Ni涂层组织和性能的影响

以机械合金化工艺制备的TiB2-40Ni和TiB2-50Ni粉末为原料,利用超音速火焰喷涂沉积不同TiB2-Ni涂层,采用扫描电镜、X射线衍射仪研究了涂层的组织和相结构,运用压痕法测定了涂层的显微硬度,通过水淬法测试涂层的抗热震性能,并研究涂层的耐熔融铝硅腐蚀性能。结果表明,TiB2-40Ni和TiB2-50Ni涂层致密,孔隙率分别为1.25%和0.12%;涂层的主要物相为TiB2和Ni;显微硬度值分别为(643.5±56.8)HV0.3与(597.9±36.1)HV0.3;涂层均具有较好的抗热震性能,其中以TiB2-50Ni涂层最佳;经过120h熔融铝硅腐蚀后发现,两种涂层均具有良好的抗熔融铝硅腐蚀性能,TiB2-50Ni涂层试样具有最好的耐腐蚀性能。     

Q235钢表面热喷涂TiB2-50Ni金属陶瓷层的组织结构和性能

目前,对超音速火焰喷涂TiB2增强金属基复合涂层的耐磨性有一定研究,但对其抗热震性能和耐熔融金属腐蚀性能的报道较少.采用机械球磨制备了TiB2-50Ni金属陶瓷复合粉末,通过超音速火焰喷涂技术在Q235钢表面制备TiB2-50Ni金属陶瓷涂层.采用扫描电镜和X射线衍射技术分析了涂层的微观组织和物相,采用HVS-1000显微硬度计测试涂层的硬度值,采用水淬法测试涂层的抗热震性能,并研究了涂层的耐熔融Al-12.07％Si合金腐蚀性及耐磨损性能.结果表明:TiB2-50Ni涂层具有层状结构,组织致密;TiB2-50Ni涂层的主要物相为TiB2和Ni,与喷涂粉末的相同;涂层的硬度值为(348±37) HV3N;涂层与基体结合良好,耐蚀性良好,经60 h的熔融Al-12.07％Si腐蚀后,磨损失重量是Q235低碳钢的1/4;涂层抗热震性能良好,耐磨性较基体明显提高.     

TiB2材料的研究现状

TiB2材料作为一种新型先进材料,由于具有强度高、硬度高、耐磨损、耐腐蚀、熔点高、蒸气压低、导电性良好等优点而被广泛研究。介绍了TiB2材料的晶体结构与性质及其制备方法,包括直接合成法、碳热法、镁热法、溶胶-凝胶法、化学气相沉积法等,并分析总结了TiB2材料的致密化、涂层、复相陶瓷、微纳米结构等应用研究热点。其中,将两种或多种方法结合起来制备TiB2,已成为降低成本、减少污染、优化性能的重要途径。     

梯度纳米硬质涂层内部应力的有限元分析

利用有限元分析法模拟计算硬质涂层Ti、TiN、TiCN和TiAlN在不同情况下所受应力状态分析。结果表明:涂层上所加载的应力越大,涂层内部残余应力越大,造成的涂层损坏也越严重;在同种基体合金情况下TiCN涂层比TiN涂层相对抗压性能较好;同一种结构硬质涂层镀在高速钢基体上较镀在硬质合金基体上耐热性较好;涂层厚度的增加导致涂层所受残余应力减小,增了基体的抗静载压力,提高了基体的抗压性;同种涂层在不同温度下工作时,温度越高,所受的残余应力越大。     

化学气相沉积技术制备TiB2涂层研究

利用TiCl4-BCl3-H2—Ar反应体系，用化学气相沉积法（CVD）在石墨基体上沉积了TiB2涂层，研究了CVD工艺如沉积温度、气体流量、滞留时间等参数对涂层的物相组成、微晶尺寸、沉积速率、沉积形貌的影响。结果表明，沉积的涂层物相由TiB2组成，随着温度的升高，微晶尺寸增大；当沉积温度为900-950℃、气体总流量...     

碳钢热喷涂镍沉积凝固过程热力耦合场的数值模拟及温度应力场的分布规律

为了进一步弄清热喷涂残余应力产生的机理、预测与控制技术,以碳钢表面热喷涂镍为例,对镍沉积凝固冷却过程进行了合理的假设和简化。利用ANSYS平台,采用热力耦合计算,模拟了涂层冷却过程,获得了温度场和应力场分布规律,分析了涂层上某些特征点的温度和应力随时间变化的情况,并探讨了基体预热温度和涂层厚度对涂层/基体界面应力的影响。结果表明,涂层温度沿中心向边缘逐渐降低,随时间延长呈降低趋势;基体温度随时间的变化呈先增加后降低趋势;涂层主要承受残余压应力作用,随基体温度升高,残余应力呈减小趋势,随涂层厚度增加,残余应力呈增大趋势。     

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.     

A novel Ti cored wire developed for wire-feed arc deposition of TiB/Ti composite coating

A novel Ti cored wire containing TiB2,Al60V40 and Ti6Al4V mixed powders was developed for wire-feed arc deposition of TiB/Ti composite coating,to enhance the hardness and wear resistance of Ti alloy.Results showed that after experiencing several chemical reactions,the wire was melted in the arc zone and turned into nonuniform droplets composed of Ti-Al-V-B melt and undecomposed TiB2 particles.With the increase of welding current,the detachment time of droplet shortened while the transfer frequency accelerated,accompanied by the improvement in coating surface quality.The spatial distribution of TiB whiskers in coating was governed by welding current.A uniform distribution could be achieved as welding current was sufficient at the expense of elevated dilution ratio,while increasing wire feeding speed could compensate the dilution loss of TiB whisker to some extent.The decomposition process of TiB2 particles and the microstructure evolution mechanism of coating was discussed in detail.The optimum coating possessed uniform microstructure,relatively low dilution ratio,and high hardness(639.1 HV0.5)as compared with Ti6Al4V substrate(326 HV0.5).Indentation morphology analysis verified the excellent performance was ascribed to the load-sharing strengthening of TiB whiskers.This study provides a high-efficiency fabrication method for the ever-developing titanium matrix composites(TMCs)coating.     

钛金属熔融Na_2B_4O_7硼化:热力学和动力学过程

以无水硼砂为硼化剂在金属钛表面进行硼化,通过XRD分析样品表面的物相组成。结果表明,当温度为900℃时,钛金属表面主要生成Na0.23TiO,基本没有硼化物生成;当温度升高到950℃时,钛金属表面只生成少量的硼化物;而当温度高于950℃时,钛金属表面有明显的硼化物生成。随着温度的升高,硼化物种TiB2的量增多,而TiB量减少。热力学分析表明,随着温度的升高,生成TiB2和TiB的趋势应该降低,这与实验结果相矛盾。根据Sar-ma的B原子在金属钛中的扩散动力学,由于低温时B原子在TiB中的扩散速度大于其在TiB2和Ti中的扩散速度,故能同时生成TiB2和TiB;而高温时由于B在Ti中的扩散速度大于其在TiB中的扩散速度,主要生成TiB2,而TiB的生成受到抑制。     

TiB_2-ZrB_2沉积层铜电极点焊镀锌钢的失效过程

为了探讨TiB_2-ZrB_2沉积层铜电极点焊镀锌钢时的失效机理,采用自制电火花设备在铜表面沉积了TiB_2-ZrB_2层。通过扫描电镜(SEM)、X射线衍射仪(XRD)和显微硬度测试等表征方法,对比分析了无沉积层电极与TiB_2-ZrB_2沉积层电极点焊镀锌钢时的失效机理。结果表明:TiB_2-ZrB_2沉积层大致可提高电极寿命4倍左右;TiB_2-ZrB_2沉积层电极点焊过程中在力和热的作用下,沉积层内部首先产生裂纹,随后脱落,随着焊接的持续,镀锌钢中的Zn元素会填充进来,为与Cu的合金化反应创造了条件;在沉积层完整性受到破坏后,TiB_2-ZrB_2沉积层电极无论是塑性变形速度,还是Cu与Zn间的合金化程度都会加剧,进而加速了失效。     

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.     

SiCW对TiB2／25SiCW陶瓷材料高温增韧效果的影响

采用热压工艺制备了ＴｉＢ２／ＳｉＣＷ陶瓷复合材料，结果表明：在ＴｉＢ２基体中添加体积分率为２５％的ＳｉＣ晶须，可显著的提高材料的断裂韧性和抗弯强度，实验表明，ＴｉＢ２／２５ＳｉＣＷ陶瓷材料的断理解韧在１０００℃内随温度的升高而增大，其原因是由于的升高使晶须径向残余压应力松驰，晶须拔出所需要的力ＦＰ减小，温度越高，晶须拔出越容易，能够被拔出的晶须量增多，拔出功增大，在低落曙下晶须以脆性断裂为主，在高     

Morphology,microstructure, and residual stress in EBPVD erbia coatings

The electron-beam physical vapor deposition of erbium-oxide coatings onto sapphire wafers is investigated to evaluate processing effects on the residual stress state and microstructure. The erbium-oxide coatings are found to be in a compressive stress state. The crystallographic texture of the erbium-oxide coating is evaluated using X-ray diffraction along with an assessment of forming the cubic erbia phase as a function of substrate temperature. In addition to the cubic erbia phase, an orthorhombic phase is found at the lower deposition temperatures. A transition is found from a two-phase erbium-oxide coating to a single phase at deposition temperatures above 948 K. The variation in morphology with deposition temperature observed in fracture cross-sections is consistent with features of the classic zone growth models for vapor-deposited oxide coatings. For high-temperature applications, a deposition process temperature above 948 K is seen to produce a stoichiometric, fully dense, and equiaxed-polycrystalline coating of cubic erbia.     

Microstructure and thermal behaviour of plasma sprayed zirconia/alumina composite coating

In thermal barrier coatings (TBC), failure occurs near or at the interface between the metallic bondcoat and topcoat. On high temperature conditions, an oxide scale which is named thermally grown oxide (TGO) occurs along the bond/topcoat interface. For diminishing the creation of TGO, a dense coating with low residual stress and thermal stress buffer layer was preferable. High hardness ceramic coatings could be obtained by gas tunnel type plasma spraying, and the deposited coating had superior property in comparison with those deposited by conventional type plasma spray method. In this study, the gas tunnel type plasma spraying system was utilized to produce a zirconia/alumina functionally graded thermal barrier coating and discussed its physical and mechanical properties, thermal behavior and high temperature oxidation resistance of the coating are discussed. Consequently, the proposed system exhibited superior mechanical properties and oxidation resistance at the expenses of a slightly lower thermal insulating effect. This interlayer is preferred in order to minimize the detrimental effect of the phase transformation of gamma-Al2O3 to alpha-Al2O3.     

Multilayer DLC coatings via alternating bias during magnetron sputtering

To combat the high residual stress problem in monolayer diamond-like carbon coatings, this paper fabricated multilayer diamond-like carbon coatings with alternate soft and hard layers via alternating bias during magnetron sputtering. The surface, cross sectional morphology, bonding structures and mechanical properties are investigated. The atomic force microscopy images indicate low bias results in rougher surface with large graphite clusters and voids suggesting low coating density. The multilayered coatings demonstrate relatively smooth surface stemming from higher bias. The cross sectional images from field emission scanning electron microscopy indicate coating thickness decreases as substrate bias increases and confirm that higher bias results in denser coating. Delamination is observed in monolayer coatings due to high residual stress. The trend of sp³/sp² fraction estimated by X-ray photoelectron spectroscopy is consistent with that of I_D/I_G ratios from Raman spectra, indicating the change of bonding structure with change of substrate bias. Hardness of multilayer diamond-like carbon coating is comparable to the coatings deposited at low constant bias but the adhesion strength and toughness are significantly improved. Alternately biased sputtering deposition provides an alternative when combination of hardness, toughness and adhesion strength is needed in an all diamond-like carbon coating.     

电子束沉积SiC/ZrO2热防护层的结构优化及其抗热震性能

高性能辐射热防护层是高超声速飞行器金属热防护系统的重要组成部分。为获得高性能的热防护层,利用L5 EB-PVD电子束物理气相沉积设备在Haynes 214镍基合金表面沉积了SiC/ZrO2防护层,测试了其在热循环条件下的抗热震性能;通过分析其沉积温度及厚度对残余热应力的影响,确定了热防护层的沉积工艺参数。结果表明:热防护层在800℃和900℃循环80次后未出现明显的宏观裂纹;1000℃循环60次后,SiC表面层应力集中区出现裂纹,在交变热应力作用下,裂纹不断扩展形成网状龟裂纹,最终导致热防护层剥落;热膨胀系数不匹配导致热防护层在急冷急热热震过程中产生热应力是导致其失效的主要原因。     

热喷涂构件中残余应力的理论分析

本文发展了一种新的分析涂层结构(平板、梁)热残余应力的模型,可以研究骤冷过程(Quenching)和冷却过程(Cooling)在涂层结构内引发的残余应力分布。与以往模型相比,其优势在于:它可以考虑源于喷涂过程的涂层孔隙率、温度梯度等因素对于涂层和基底内残余应力的影响。其中孔隙率和温度分布由计算机模拟涂层沉积过程得到。另外,当基底的材料和几何参数被固定时,我们分析了诸如涂层的理想模量、厚度、热膨胀系数等参数,对于涂层结构中最终残余应力分布的改变机理。