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%.     

Ti-Al-Si-N涂层界面微结构研究

采用多元等离子体浸没离子注入与沉积装置制备Ti-Al-Si-N涂层,借助X射线衍射仪、X射线光电子能谱、透射电子显微镜、纳米探针和原子力显微镜等系统研究涂层界面微结构与力学性能。研究结果表明:Ti-Al-Si-N涂层具有Si3N4界面相包裹TiAlN纳米晶复合结构,Si元素掺杂诱发涂层发生明显晶粒细化效应。随涂层Si含量增加,TiAlN晶粒尺寸显著降低,界面Si3N4层厚度增加。当Si3N4界面层厚度小于1nm并与TiAlN晶粒共格外延生长时,Ti-Al-Si-N涂层表现超高硬度约40GPa,当Si3N4界面相厚度增至2nm并呈非晶态存在时,涂层硬度降至约29GPa。     

氮气气压对多弧离子镀TiSiN涂层显微结构与腐蚀行为的影响

为了研究氮气气压对Ti Si N涂层显微结构与腐蚀行为的影响,采用自制多弧离子镀设备,在抛光的单晶(100)硅片与不锈钢基底上沉积Ti Si N涂层,沉积气压0.5~2.5 Pa,利用X射线衍射仪(XRD)、X射线光电子能谱(XPS)、高分辨透射电子显微镜(HRTEM)与电化学阻抗谱(EIS)表征涂层显微结构与电化学性能。结果表明:沉积的Ti Si N涂层为纳米晶-非晶复合结构,其中纳米Ti N晶体被非晶的Si3N4包围。当氮气气压从0.5 Pa升高到2.5 Pa之后,Ti Si N涂层晶粒尺寸由19.5 nm减小到8.0 nm。电化学阻抗随着氮气气压升高先增大后逐渐下降,沉积气压为1.0 Pa时,涂层抗腐蚀性能最强。     

表面粗糙度对PS-PVD热障涂层陶瓷层沉积的影响

研究基于等离子喷涂-物理气相沉积(PS-PVD)工艺的沉积表面的粗糙度对YSZ陶瓷层结构的影响,初步阐明了表面粗糙度对陶瓷层气相沉积过程的影响和涂层结构的形成规律。采用PS-PVD工艺在预制有NiCoCrAlYTa黏结层的K417G高温合金上制备YSZ陶瓷层;采用SEM、粗糙度检测仪、3D表面形貌仪等方法分析PS-PVD YSZ陶瓷涂层的形貌和结构特征。基体表面粗糙度对PS-PVD涂层结构有很大影响。结果表明:当基体表面粗糙度分别为 R a≤2μm, 2μm< R a<6μm, R a≥6μm时,涂层粗糙度分别在3.5~5,6~10,10~15μm区间;特征表面形貌"菜花头"的直径随着基体表面粗糙度的增加而逐渐增大, d P=38.5μm, d 280S =25.5μm, d 60S =38.7μm, d 24S =102μm, d S=137μm。表面粗糙度主要通过PS-PVD气相沉积过程中的阴影效应来影响涂层生长和形成差异性结构,随着基体表面粗糙度的增加,YSZ陶瓷层受阴影效应影响增大,表面形貌"菜花头"尺寸和柱状结构间间隙增大,形成更加疏松的结构。     

表面粗糙度对PS-PVD YSZ陶瓷层性能的影响EI北大核心CSCD

采用PS-PVD工艺在预制有NiCoCrAlYTa黏结层的K417G高温合金上制备YSZ陶瓷层;采用万能拉伸试验机、粒子冲刷仪、静态氧化炉等设备测试PS-PVD YSZ陶瓷涂层的结合强度、抗粒子冲刷和抗高温氧化性能;采用SEM和EDS分析涂层表面、截面形貌和元素分布等。结果表明:表面粗糙度对YSZ陶瓷层拉伸结合强度、抗粒子冲刷和抗高温氧化性能的影响很大。随着粗糙度的增大,结合强度先增大而后减小。Ra=0.40μm表面上沉积的YSZ涂层,其结合强度最高,达到23.5 MPa。拉伸断裂发生在涂层内部,并距离黏结层40~70μm的位置。随着表面粗糙度的增大,冲刷速率先减小而后增大,Ra=0.40μm涂层的抗粒子冲刷性能最好,冲刷速率仅为2.8×10^-3 g/g,表面起伏小和孔隙率低是涂层具有良好抗粒子冲刷性能的重要原因。不同表面粗糙度制备的YSZ涂层均能生成致密连续的热生长氧化物(TGO)层。粗糙度大则生长的TGO起伏大,更容易导致局部增厚和应力集中而失效。     

离子束倾斜入射抛光对表面粗糙度的影响

基于光学元件离子束高精度确定性抛光技术,在自行研制的离子束抛光机床上,本文研究了离子束倾斜入射抛光对光学材料熔石英表面粗糙度的影响.为了在离子束抛光中改善表面粗糙度,采用了0°～80°之间不同入射角度的离子束倾斜抛光和倾斜45°入射均匀去除两种实验方案进行研究,其中不同入射角度抛光实验研究结果表明:离子束垂直入射抛光较难改善表面粗糙度,倾斜入射抛光可以较好地改善表面粗糙度,入射角为30°～60°之间时抛光效果最佳,表面粗糙度得到明显改善;倾斜45°入射均匀去除抛光实验结果表明表面粗糙度的RMS值由抛光前(0.92±0.06)nm下降到(0.48±0.04)nm,提高了光学零件的表面质量,验证了离子束倾斜入射抛光可以较好地改善表面粗糙度,实现了离子束倾斜抛光超光滑表面的生成.     

工作气压对室温溅射柔性AZO薄膜性能的影响

采用射频磁控溅射法在PEN衬底上室温制备了AZO薄膜,并对不同工作气压下(0.05～0.4Pa)沉积薄膜的结构及光电性能进行了研究。结果表明,薄膜具有良好的c轴择优取向,随工作气压增大,薄膜(002)峰强度减弱,晶粒减小,表面粗糙度增大,电学性能下降,薄膜可见光透过率变化不大,但禁带宽度变窄。与玻璃衬底相比,PEN衬底上沉积的AZO薄膜拥有更高的品质因数,获得的最佳电阻率、载流子浓度和霍尔迁移率分别为1.11×10-3Ω.cm、4.14×1020cm-3和13.60cm2/(V.s),该薄膜可见光的绝对透射率达到95.7%。     

沉积入射角度对热障涂层形貌和性能的影响

采用真空电弧镀（ARC）技术在DZ125合金基体上制备NiCrAlYSi(HY3)金属粘结层,然后采用电子束物理气相沉积（EB-PVD）技术,分别以0°、20°、40°、60°和80°五种入射角度沉积氧化钇稳定氧化锆（6～8YSZ）陶瓷涂层,研究了入射角度对涂层形貌和性能的影响。结果表明：五种入射角度的热障涂层均能形成柱状晶结构,随着入射角度增加,孔隙率和柱状晶倾斜角度均逐渐增加,涂层厚度逐渐减小;对带涂层试样进行结合强度测试,入射角度0°～40°时涂层的结合强度均在55MPa以上,入射角度增加到80°时,结合强度降低到15.7MPa;热冲击条件下,陶瓷面层和基体之间形成TGO,由于不同入射角度下涂层孔隙率不同,TGO生长速度不一致,导致其热冲击寿命存在明显差异,入射角度为0°～40°时涂层的热冲击寿命均超过4000次,入射角度为60°时涂层的热冲击寿命为3371次,入射角度为80°时涂层的热冲击寿命最短,仅为1836次。     

基于铝热反应FeCrNiCuAlSn_(0.5)高熵合金涂层的制备

高熵合金(HEA)由于其多主元和高混合熵的特点,具有一些传统合金难以实现的优异性能,在表面技术领域具有很大的应用前景。本研究采用基于铝热反应/喷射沉积的高熵合金熔覆涂层技术,在45钢表面制备了FeCrNiCuAlSn_(0.5)高熵合金涂层,并采用XRD、SEM和EDS分析了FeCrNiCuAlSn_(0.5)高熵合金涂层的相结构、显微组织及元素分布,利用维氏硬度仪、顶断试验机和球盘式摩擦计测定了涂层的硬度、结合强度及摩擦磨损性能。结果表明,喷射涂层主要由FCC相和BCC相组成,可能含有少量的Ni_3Sn_2相。涂层组织为树枝晶,二次枝晶臂间距大约为(5.25±2.75)μm,平均冷却速度达到2.37×10~4K/s。涂层与基体交界处未出现气孔、夹杂等缺陷,实现了良好的冶金结合,涂层与基体的平均结合强度为(412.8±16) MPa。涂层的平均显微硬度值为(539±10)HV,摩擦系数为0.50,磨损率为(7.24±0.52)×10~(-6)mm~3/(N·m);而45钢基体的摩擦系数为0.75,磨损率为(1.45±0.35)×10~(-5)mm~3/(N·m),表现出比基体更为优异的耐磨性能。     

N_2流量对HIPIMS/DCMS共沉积制备TiAlCrN涂层结构及性能的影响

利用高功率磁控溅射与直流反应磁控溅射共沉积技术制备了不同N_2流量下的TiAlCrN复合硬质涂层。采用X射线衍射仪(XRD)、薄膜综合性能测试仪以及大气球盘摩擦磨损试验机分析测试了涂层的微观组织结构、力学性能及摩擦学性能。结果显示:随N_2流量的提高,涂层沉积速率先上升后下降;XRD测试表明增加N_2流量可有效抑制h-Al N相的生成,并且改善了涂层的结晶性能;同时,表面粗糙度先下降后升高,最小值可达45.7 nm;涂层硬度逐渐上升,而弹性模量在取得最大值后呈下降趋势,最大值分别为31.2和423.8 GPa;划痕临界载荷在N_2流量为250 m L/min时获得最优值5.5 N。摩擦学性能方面,随N_2流量的提高,涂层磨损率先下降后上升,最小值为2.6×10~(-17)m~3/N·m。由此可见,在一定范围内调节N_2流量可显著改善涂层的强度及耐磨损性能。     

Hydrothermal-electrochemical codeposited hydoxyapatite/yttria-stabilized zirconia composite coating

Hydroxyapatite(HA)/yttria-stabilized zirconia(YSZ) composite coatings were deposited on titanium substrates using a hydrothermal electrochemical method in an electrolyte containing calcium, phosphate ions and YSZ particles. HA/YSZ composite coatings were prepared in different conditions with different electrolyte temperatures(100 ∼ 200°C), current densities(0.1 ∼ 10.0 mA/cm²), and particles content in bath(0 ∼ 100 g/L). The effect of YSZ additions on the phase composition, microstructure, thermal stability, corrosion behavior and the bonding strength of HA/YSZ composite coatings were studied. The results show that crystallinity of HA in HA/YSZ composite coatings increase continuously with the electrolyte temperature and close to stoichiometric HA. The n(Ca)/n(P) ratio at 200°C is about 1.67 according with stoichiometric HA. YSZ particles are imbedded uniformly between the HA crystals. The average HA crystal size are reduced owing to the additions of YSZ particles. After annealing at 1200°C, tetragonal phase YSZ tend to react with the released CaO to form cubic phase YSZ and CaZrO₃, which cause destabilization of HA to decompose into more α-TCP phase. The bonding strength between HA/YSZ composite coatings and titanium substrates increase with increasing volume content of YSZ in the composite coatings (V %). HA/YSZ composite coatings exhibit a better electrochemical behavior than pure HA coatings and uncoated Ti metals.     

Preparation of YSZ/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composite coatings via electrophoretic deposition of nanopowders

Using electrophoretic deposition (EPD), we have produced YSZ individual ceramic coatings and YSZ/Al₂O₃ composite coatings for a wide range of applications in modern materials research. YSZ and Al₂O₃ nanopowders were prepared by high-energy physical dispersion techniques, namely, by a laser evaporation–condensation process and electroexplosion of wire, respectively. Stable nonaqueous suspensions for the EPD process have been prepared using YSZ and Al₂O₃ nanopowders with an average particle size of 11 and 22 nm, respectively. The YSZ/Al₂O₃ composite coating produced by sintering at 1200°C has been shown to have higher density in comparison with the YSZ individual coating produced at the same temperature. X-ray diffraction characterization showed that the YSZ/Al₂O₃ composite coating consisted of two crystalline phases: α-Al₂O₃ (corundum) (42 wt %) and cubic ZrO₂〈Y₂O₃〉 (58 wt %). Quantitative analysis of electron micrographs of the surface of the films showed that the YSZ individual coating produced by sintering at 1200°C had a loose structure and contained pores (9%), as distinct from the composite coating, which had a dense, porefree grain structure.     

Dielectric properties of YSZ high-k thin films fabricated at low temperature by pulsed laser deposition

Yttria-stabilized zirconia (YSZ) films were deposited on Pt-coated silicon substrates and directly on n-type Si substrates, respectively, by pulsed laser deposition (PLD) technique using a YSZ (5 mol% Y₂O₃-stabilized ZrO₂) ceramic target. The YSZ films were deposited in 1.5×10⁻² Pa O₂ ambient at 300 °C and in situ post-annealed at 400 °C. X-ray diffraction (XRD) and differential thermal analysis measurements demonstrated that YSZ remained amorphous. The dielectric constant of amorphous YSZ was determined to be about 26.4 by measuring Pt/YSZ/Pt capacitor structure. The 6-nm-thick amorphous YSZ films with an equivalent oxide thickness (EOT) of 1.46 nm and a low leakage current of 7.58×10⁻⁵ A/cm² at 1 V gate voltage exhibit good electrical properties. YSZ thin films fabricated at low temperature 300 °C have satisfactory dielectric properties and could be a candidate of high-k gate dielectrics.     

Effects of different acetylene/nitrogen ratios on characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition

The effects of C₂H₂/(C₂H₂ + N₂) ratios on the characteristics of carbon coatings on optical fibers prepared by thermal chemical vapor deposition are investigated. The C₂H₂/(C₂H₂ + N₂) ratios are set to 60, 70, 80, 90, and 100%. Additionally, the deposition temperature, working pressure, and mass flow rate are 1003 K, 133 kPa, and 40 sccm, respectively. The deposition rate, microstructure, and electrical resistivity of carbon coatings are measured. The low-temperature surface morphology of carbon-coated optical fibers is elucidated. Experimental results indicate that the deposition rate increases with increasing the C₂H₂/(C₂H₂ + N₂) ratio, and the deposition process is located at a surface controlled regime. As the deposition rate increases, the electrical resistivity of carbon coatings increases, while the ordered degree, nano-crystallite size, and sp² carbon atoms of the carbon coatings decrease. Additionally, the low-temperature surface morphology of the carbon coatings shows that if the carbon coating thickness is not smaller than 289 nm, decreasing the deposition rate is good for producing hermetic optical fiber coatings.     

Atomic layer deposition of BN thin films

Boron nitride has for the first time been deposited from gaseous BBr₃ and NH₃ by means of atomic layer deposition. The deposition temperatures were 400 and 750 °C, and the total pressure was 10 torr. The BN films, deposited on silica substrates, showed a turbostratic structure with a c-axis of 0.70 nm at a deposition temperature of 750 °C as determined by X-ray diffraction. The films deposited at 400 °C were significantly less ordered. The film density was obtained by means of X-ray reflectivity, and it was found to be 1.65–1.70 and 1.90–1.95 g cm⁻³ for the films deposited at 400 and 750 °C, respectively. Furthermore, the films were, regardless of deposition temperature, fully transparent and very smooth. The surface roughness was 0.3–0.5 nm as measured by optical interferometry.     

Effect of annealing temperature on the structural-microstructural and electrical characteristics of thallium bearing HTSC films prepared by chemical spray pyrolysis technique

In order to get good quality reproducible films of Tl : HTSC system, we have studied the different annealing conditions to finally achieve the optimized annealing condition. In the present investigation, Tl-Ca-Ba-Cu-O superconducting films have been prepared on YSZ (100) and MgO (100) single crystal substrates via precursor route followed by thallination. The post deposition heat treatments of the precursor films were carried out for various annealing temperatures (870°C, 890°C) and durations (1 and 2 min). The optimized thallination procedure occurred at 870°C for 2 min into good quality films withT _c (R = 0) ∼ 103 K for YSZ andT _c (R = 0) ∼ 98 K for MgO substrates, respectively. Further we have correlated the structural/microstructural characteristics of the films.     

Thermal and crystallization behavior of zirconia precursor used in the solution precursor plasma spray process

Yttria stabilized zirconia (7YSZ) solution precursor has been successfully used in the deposition of high durability thermal barrier coatings. In this paper, the thermal and crystallization behaviors of 7YSZ precursor were investigated by TG-DTA, FTIR and XRD. The results show that the precursor decomposition and crystallization temperatures greatly depend on heating rate e. g. 74°C for the crystallization temperature when tripping the heating rate. With a 10 °C/min heating rate, the weight loss due to precursor pyrolysis occurs predominantly at temperatures below 500 °C. A small weight loss due to the oxidation of residual carbon is detected from 800 °C to 950 °C. The complete crystallization of the tetragonal phase was determined to be around 500 °C by DTA and XRD analyses with a 10 °C/min heating rate. The crystallization kinetics and the activation energy of amorphous 7YSZ precursor were investigated by variable heating rate DTA. The calculated activation energy is 66.2 kJ/mol. The Avrami parameter value was determined to be 2.68, which indicates that crystallization nucleation and growth is diffusion-controlled. The crystalline phase of 7YSZ coatings deposited by the Solution Precursor Plasma Spray process was identified by XRD and Raman spectrum. The average YSZ grain size in the SPPS coating was determined to be 61 nm.     

Electrochemical property of multi-layer anode supported solid oxide fuel cell fabricated through sequential tape-casting and co-firing

In this work, a multi-layer anode supported solid oxide fuel cell (SOFC) is designed and successfully prepared through sequential tape casting and co-firing. The single cell is consisted of NiO-3YSZ (3YSZ: 3 mol.% yttria doped zirconia) anode support, NiO-8YSZ (8YSZ: 8 mol.% yttria stabilized zirconia) anode functional layer, dense 8YSZ electrolyte layer, and porous 3YSZ cathode scaffold layer with infiltrated La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ cathode. The clear interfaces and good contacts between each layer, without element inter-diffusion being observed, suggest that this sequential tape casting and co-firing is a feasible and successful route for anode supported single cell fabrication. This cell exhibits remarkable high open circuit voltage of 1.097 V at 800°C under room temperature humidified hydrogen, with highly dense and gastight electrolyte layer. It provides a power density of 360 mW/cm² under operation voltage of 0.75 V at 800°C and a stable operation of ～110 h at 750°C under current density of ?300 mA/cm². Furthermore, this cell also presents encouraging electrochemical responses under various anode hydrogen partial pressures and maintains high power output at low fuel concentrations.     

Direct nanocrystalline hydroxyapatite formation on titanium from ultrasonated electrochemical bath at physiological pH

An electrochemical method of producing nanocrystalline hydroxyapatite coatings on titanium surface is reported. The bath contained Ca(NO₃)₂ and NH₄H₂PO₄ in the molar ratio 1.67:1. The electrolyte was maintained at physiological pH and was ultrasonically agitated throughout the time of electrolysis. Coatings were deposited for 30 min at 10 and 15 mA/cm² and contained mono hydroxyapatite phase whose crystal sizes were lower than 30 nm. These sizes are comparable to the size of the bone hydroxyapatite crystals. Small globules of hydroxyapatite covered the coating surface completely. Fourier transformed infra-red spectroscopy (FT-IR) studies showed that the coatings contained large amounts of hydroxide and phosphate groups to enable the formation of hydroxyapatite. The coatings had a roughness (R_a) of about 0.3 μm and water contact angles of about 49°. Ultrasonic agitation promoted the formation of nanocrystalline structure which will help in better attachment of bone tissues to the implant surface.     

Optical properties of the Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings

Investigations of bilayer and trilayer Al₂O₃/SiO₂ and Al₂O₃/HfO₂/SiO₂ antireflective coatings are presented in this paper. The oxide films were deposited on a heated quartz glass by e-gun evaporation in a vacuum of 5 × 10^?3 [Pa] in the presence of oxygen. Depositions were performed at three different temperatures of the substrates: 100 °C, 200 °C and 300 °C. The coatings were deposited onto optical quartz glass (Corning HPFS). The thickness and deposition rate were controlled with Inficon XTC/2 thickness measuring system. Deposition rate was equal to 0.6 nm/s for Al₂O₃, 0.6 nm ? 0.8 nm/s for HfO₂ and 0.6 nm/s for SiO₂. Simulations leading to optimization of the thin film thickness and the experimental results of optical measurements, which were carried out during and after the deposition process, have been presented. The optical thickness values, obtained from the measurements performed during the deposition process were as follows: 78 nm/78 nm for Al₂O₃/SiO₂ and 78 nm/156 nm/78 nm for Al₂O₃/HfO₂/SiO₂. The results were then checked by ellipsometric technique. Reflectance of the films depended on the substrate temperature during the deposition process. Starting from 240 nm to the beginning of visible region, the average reflectance of the trilayer system was below 1 % and for the bilayer, minima of the reflectance were equal to 1.6 %, 1.15 % and 0.8 % for deposition temperatures of 100 °C, 200 °C and 300 °C, respectively.