溶胶浸渗处理对EB-PVD 制备的YSZ电解质涂层的影响

为探索溶胶浸渗处理对电子束物理气相沉积(EB-PVD)制备8%摩尔比的氧化钇稳定氧化锆(8YSZ)涂层微观结构及性能的影响,采用EB-PVD工艺在沉积速率1μm/min的条件下制备了8YSZ电解质涂层.制备态涂层的断面表现为疏松的柱状晶结构,导致涂层的气密性差,因此对涂层进行了溶胶浸渗处理,即首先在负压下将涂层浸渗在钇锆的溶胶内,再进行550℃保温2 h的热处理.SEM分析表明,溶胶分解产物可以堵塞柱状晶间的孔隙,其渗入涂层的深度可达3μm.浸渗处理后,涂层的气体扩散系数由未处理态的6.78×10-5cm4/(N.s)降低至8次浸渗处理后的6.54×10-6cm4/(N.s).8次溶胶浸渗处理后涂层的电导率相比处理前提高不超过10%.     

EB-PVD在热障涂层中的研究及应用

EB-PVD是以高能电子束为热源的一种蒸发镀膜技术.在真空的环境下,高能离子束轰击靶材(金属,陶瓷等),使其融化、升华、蒸发,最后沉积在基片上.由于EB-PVD技术具有蒸发和沉积速率高,涂层致密,化学成分易于精确控制,可得到柱状晶组织,无污染,热效率高,基片与薄膜之间有较强的结合力等诸多优点,已被广泛应用于国防和民用领域.本文介绍了EB-PVD技术在制备热障涂层时优势、不足与改进措施.     

EB-PVD及其制备功能涂层的研究进展

介绍了电子束物理气相沉积(EB-PVD)设备的结构、工艺技术特点等,重点介绍了EB-PVD技术在制备各种防护涂层方面所取得的成果及研究进展.     

热处理对EB-PVD制备的TiAl/Nb复合材料微观组织的影响

对利用EB-PVD技术制备的TiAl/Nb微层板进行了热处理,分析了沉积态材料与热处理态材料的组织结构和物相的变化。热处理TiAl/Nb中态富Ti的TiAl层中成分沿沉积方向呈有规律的梯度变化但未形成周期,界面处的反应扩散区由B2相组成;TiAl层、扩散区和Nb层的显微组织形貌依次为含月牙形亚晶的柱状晶、细小等轴晶和粗大等轴晶;经1000℃/16h的真空退火处理后,Nb层和扩散区会因完全扩散而消失。     

层板复合型TiAl基合金微层板的制备及组织性能研究

详细介绍了箔片热加工和电子束物理气相沉积(EB-PVD)在制备TiAl基合金微层板方面的特点及研究现状.重点讨论了EB-PVD制备TiAl基合金微层板的组织与性能,结果表明:TiA1基合金薄板的显微组织结构为非平直的柱状晶,亚结构为月牙形形貌;TiAl/Nb微层板中Nb层的显微组织形貌为粗大的等轴晶;TiAl/NiCoCrAl微层板中NiCo-CrA1层则主要由平直柱状晶结构的γ-Ni相组成.TiA1基合金微层板具有比TiAl基合金薄板更好的常高温力学性能,尤其是在750℃左右的高温环境中,TiAl/NiCoCrAl微层板的增韧效果最佳,伸长率高达72.2％;而TiAl/Nb微层板则表现出最好的高温综合性能,其高温抗拉强度高达443.1MPa,几乎与其室温时的抗拉强度持平.     

合金化组元(Al,Cr,Si,Ti)含量对激光沉积(FeNiCo)-(AlCrSiTi)非等原子比多组元合金涂层组织与力学性能的影响

采用激光沉积制备不同含量合金化组元(Al,Cr,Si,Ti)的(FeNiCo)-(AlCrSiTi)多组元合金涂层,研究合金化组元含量对涂层组织与力学性能的影响.结果表明:随着合金化组元(Al,Cr,Si,Ti)含量的增加,涂层中面心立方(FCC)相含量逐渐降低,由FCC相+体心立方(BCC)相的双相结构转变为以BCC相为主的结构,且BCC相内纳米析出相颗粒密度显著增加,颗粒平均尺寸由97 nm降低至36 nm;同时,随着合金化组元含量的增加,涂层中等轴晶组织区域面积增大,等轴晶显著细化,平均晶粒尺寸最小仅为10.8μm;涂层截面平均显微硬度由271HV0.1上升至718HV0.1,但涂层抗弯强度由2208 MPa降低至1374 MPa,所能承受的最大弯曲应变也由7.3％降低至0.47％.     

溅射靶材对TiAlN涂层形貌、结构和力学性能的影响

采用粉末冶金和真空熔炼方法制备了原子比为Ti50Al50的合金靶材,利用磁控溅射工艺在同一工艺参数下制备了TiAlN涂层,借助扫描电镜、原子力显微镜、X射线衍射仪、纳米压痕和结合强度实验,研究了溅射靶材对TiAlN涂层的形貌、结构和力学性能的影响。结果表明:粉末靶材中Ti和Al以单质相存在,Ti镶嵌于Al基体周围,熔炼靶材中形成了TiAl和Ti3Al合金化片层组织;由于两种靶材在组织结构和导热性能上的不同导致其溅射产额、靶材温度和溅射金属离子能量等都出现了明显的差异;对涂层的影响表现为,相比于熔炼靶材涂层,粉末靶材涂层的沉积速率高44%,表面粗糙度低24%,涂层表面熔滴数目和尺寸较小;粉末靶材涂层呈现Ti2AlN相等轴晶生长方式,熔炼靶材涂层由于沉积温度较高表现为Ti2AlN相和TiN相,以等轴晶和柱状晶混合生长;相结构的不同导致涂层的硬度和结合强度出现差异,粉末靶材涂层硬度为25.69 GPa,结合强度属于HF-3,熔炼靶材涂层的硬度为28.22 GPa,结合强度属于HF-5。     

等离子喷涂-物理气相沉积7YSZ热障涂层高温氧化过程中的阻抗谱分析

采用等离子喷涂-物理气相沉积(PS-PVD)在预处理的粘结层表面制备了柱状结构的7YSZ热障涂层,并在大气环境下测试了该涂层在950℃的静态高温氧化性能。利用透射电镜(TEM)、扫描电子显微镜(SEM)及能谱仪(EDS)等对热障涂层进行了表征,并采用阻抗谱分析研究了该涂层在高温氧化过程中的结构演变过程。结果表明,7YSZ热障涂层是由二次柱状晶及其纳米间隙、柱状枝晶间孔隙和分布在枝晶上的微纳米固态颗粒组合形成。阻抗分析表明,热生长氧化物(TGO)层在高温氧化150 h后氧空位含量减少,致密度增加。在高温氧化过程中,二次柱状晶的内部结构没有发生明显改变。此外,氧化过程中YSZ层内形成的烧结收缩裂纹是导致YSZ晶界电容值减小、电阻值增加的主要原因。     

EB-PVD锆酸镧热障涂层抗高温氧化性能研究EI北大核心

在高温合金基体上采用EB-PVD技术制备了锆酸镧(La2Zr2O7,LZ)热障涂层,研究了涂层的抗高温氧化性能;采用XRD分析了经历不同氧化时间后涂层的相结构,分别采用SEM和EDS观察和分析了氧化前后涂层的显微形貌和成分,并对可能导致涂层失效的原因进行了分析。结果表明,在相同的试验条件下,LZ的氧化增重速率低于8%Y2O3稳定氧化锆(质量分数);氧化试验后LZ涂层保持了沉积态完整的细小柱状晶结构,表面的显微形貌也基本保持了沉积态的状况;XRD分析结果显示,涂层没有发生可观察到的相变和烧结现象;循环氧化后,LZ涂层局部区域的柱状晶头部发生了断裂脱落失效,LZ的热膨胀系数较低、弹性模量较大以及断裂韧度较低,是造成这种现象的主要原因。     

工艺参数对EB-PVD制备YSZ涂层的影响

为探讨电子束物理气相沉积(EB-PVD)制备8 mol.%氧化钇稳定氧化锆(8YSZ)涂层过程中工艺参数对涂层致密性、表面粗糙度和晶粒择优取向生长的影响,利用扫描电镜、原子力显微镜和X射线衍射技术对涂层的上述性能进行了分析.分析结果表明,随沉积速率由750 nm/min下降至20 nm/min,YSZ涂层的晶粒逐渐聚合长大,晶粒之间的孔隙减少,涂层的气体扩散系数相应地由2.41×10-4cm4/(N·s)下降至6.56×10-5cm4/(N·s).YSZ涂层的表面粗糙度随靶基距的提高逐渐降低,涂层的晶体学取向随蒸汽粒子入射角的改变而改变,入射角为30°时(111)晶面具有平行于涂层表面排列的趋势,入射角为45°时(311)和(420)晶面具有平行于表面排列的趋势,而入射角为60°时(220)和(331)晶面具有平行于表面排列的趋势.     

Improved oxidation resistance and diffusion barrier behaviors of gradient oxide dispersed NiCoCrAlY coatings on superalloy

NiCoCrAlY has been used as the bond coat material in thermal barrier coating (TBC) to protect the superalloy substrate from oxidation and hot-corrosion. Inter-diffusion of elements between the coating and substrate could degrade the oxidation resistance of the coating and the mechanical properties of the superalloy. In this work, a gradient oxide dispersed (OD) NiCoCrAlY coating was produced onto DZ125 superalloy using electron beam-physical vapor deposition (EB-PVD). For comparison, conventional NiCoCrAlY (OD free) coated specimens were also produced by EB-PVD. The oxidation and inter-diffusion behaviors of the coated specimens at 1373 K were investigated. As compared to OD free coating, the OD coating exhibits not only a lower oxidation rate but also an improved oxide scale adherence because outward diffusion of the elements such as Ta, W and Hf from the superalloy was effectively blocked by the OD zone. Meanwhile, the presence of minor Hf in the OD coating contributes to the improved oxide scale adherence by reactive element mechanism.     

EB-PVD热障涂层对高温合金基体断裂特征影响的研究

采用EB－PVD方法在K3合金上（包括铸态和经标准热处理两种状态）沉积了由NiCoCrAlY金属粘结层和YSZ涂层顶层组成的双层结构的热障涂层,对未涂层和涂层试样的拉伸性能进行了评估,并分析了涂层的制备和中间处理过程中的基体的微观结构的变化。结果表明,在热障涂层的沉积以及中间处理过程中（真空前处理及后处理）,基体的铸态组织得到改善,产生了析出强化,使得在铸态K3合金基体上沉积热障兴层后基体的拉伸强度由800MPa提高到1050MPa,而在经过标准热处理的合金基体上沉积热障涂层对基体的力学性能几乎没有影响。     

Microstructural evolution of titanium nitride (TiN) coatings produced by reactive ion beam-assisted, electron beam physical vapor deposition (RIBA, EB-PVD)

Titanium nitride (TiN) coatings have been successfully deposited on 304 stainless steel substrates by reactive ion beam-assisted, electron beam-physical vapor deposition (RIBA, EB-PVD). The hardness values of the TiN coatings varied from 800 to 2500 VHN depending on the processing condition. The lattice parameter and hardness variation were correlated with processing parameters such as: deposition rate, bias, ion source energies, process gas, substrate temperature, and coating composition. The hardness of the TiN coatings increased with increasing ion energy. The ion energies combined with the deposition rate were the limiting factors controlling the degree of surface texturing. Surface texturing was only observed for those coatings deposited >8 Å/s.     

Numerical study on modification of ceramic coatings by high-intensity pulsed ion beam

ZrO₂ ceramic coatings, which often call thermal barrier coatings (TBCs), fabricated by electron beam physical vapor deposition (EB-PVD), are widely used in high-temperature environment of aircraft and industry gas-turbine engines, because of the excellent strain tolerance imparted by the columnar structure. However, channels separating the columnar grains in EB-PVD TBCs provide paths for oxygen or other aggressive species from ambient atmosphere into the bond coat, resulting in the premature spallation-failure during high-temperature service. In our previous study, high-intensity pulsed ion beam (HIPIB) technique has been proposed to modify the EB-PVD TBCs, where a melted, densified top layer can be produced as a result of extremely thermal effect induced by the HIPIB irradiation. In this paper, HIPIB melting process is investigated numerically using a physical model based on experimental data, taking into account the surface morphology of HIPIB-melted TBCs to explore the mechanism of interaction between HIPIB and the coatings. Deposition process of the beam energy in TBCs was simulated by Monte Carlo method, and the non-linear equations describing the thermal conducting process were solved numerically based on the deposited energy to obtain the evolution of the temperature field of TBCs. The calculated melting depth of irradiated EB-PVD TBCs is consistent with results obtained in the HIPIB irradiation experiments.     

热障陶瓷涂层的最新发展

综述了现代航空发动机用热障陶瓷涂层的最新发展，着重介绍了双陶瓷层，电子束物理气相沉积（EB－PVD）和溶液等离子喷涂（SPS）纳米热障陶瓷涂层的性能和特点。     

Tailored microstructure of zirconia and hafnia-based thermal barrier coatings with low thermal conductivity and high hemispherical reflectance by EB-PVD

Zirconia and hafnia based thermal barrier coating materials were produced by industrial prototype electron beam-physical vapor deposition (EB-PVD). Columnar microstructure of the thermal barrier coatings were modified with controlled microporosity and diffuse sub-interfaces resulting in lower thermal conductivity (20–30% depending up on microporosity volume fraction), higher thermal reflectance (15–20%) and more strain tolerance as compared with standard thermal barrier coatings (TBC). The novel processed coating systems were examined by various techniques including scanning electron microscopy (SEM), X-ray diffraction, thermal conductivity by laser technique, and hemispherical reflectance.     

Overview on the Development of Nanostructured Thermal Barrier Coatings

Thermal barrier coatings （TBCs） have successfully been used in gas turbine engines for increasing operation temperature and improving engine efficiency. Over the past thirty years, a variety of TBC materials and TBC deposition techniques have been developed. Recently, nanostructured TBCs emerge with the potential of commercial applications in various industries. In this paper, TBC materials and TBC deposition techniques such as air plasma spray （APS）, electron beam physical vapor deposition （EB-PVD）, laser assisted chemical vapor deposition （LACVD） are briefly reviewed. Nanostructured 7-8 wt pct yttria stabilized zirconia （7-8YSZ）TBC by air plasma spraying of powder and new TBC with novel structure deposited by solution precursor plasma spray （SPPS） are compared. Plasma spray conditions, coating forming mechanisms, microstructures,phase compositions, thermal conductivities, and thermal cycling lives of the APS nanostructured TBC and the SPPS nanostructured TBC are discussed. Research opportunities and challenges of nanostructured TBCs deposited by air plasma spray are prospected.     

Thermocyclic Behavior of Differently Stabilized and structured EB-PVD thermal barrier coatings

The electron-beam physical vapor deposition (EB-PVD) process provides distinctive coatings of a unique columnar microstructure for gas turbine components. Main advantage of this structure is superior tolerance against straining, erosion and thermoshock, thus giving it a major edge in lifetime. This paper outlines the interaction between chemical composition and microstructural evolution EB-PVD zirconia-based thermal barrier coatings (TBCs) and their respective lifetimes in cyclic burner rig and furnace tests. Customizing TBC microstructure by adjusting EB-PVD processing parameters is emphasized. A structural zone diagram for PVD is modified by interconnecting the influence of substrate rotation with microstructural evolutions. Finally, some basic aspects of single source and dual source evaporation are compared.     

Distribution and structures of nanopores in YSZ-TBC deposited by EB-PVD

Distribution and arrangement of nanopores in an YSZ (7 wt% Y₂O₃–ZrO₂)-thermal barrier coating (TBC) deposited by an electron beam-physical vapor deposition (EB-PVD) have been investigated by means of transmission electron microscopy. The YSZ-TBC deposited by the EB-PVD showed a typical columnar structure normal to the bond coat surface on the substrate. It has been generally believed that one column is a single crystal and grows continuously from the substrate. In the present study, however, it was found that each column consisted of a number of subcolumns with different misorientations and contained nanopores at the subcolumn boundaries. In addition to the nanopores at the subcolumn boundaries, nanopores with smaller size were observed within subcolumns, and were arranged periodically perpendicular to the growth direction of the subcolumns. Such arrangement and distribution of nanopores may be due to the misorientation of YSZ plate-like grains in the formation and coalescence processes of the YSZ subcolumns.