Enhancement of piezoelectric and ferroelectric performances in (Na0.85K0.15)0.5Bi0.5TiO3 films with BaTiO3 interlayers

In this work, in order to optimize the electrical performance of (Na_0.85K_0.15)_0.5Bi_0.5TiO₃ (NKBT) thin films, 20 nm-thick BaTiO₃ (BTO) layer was utilized by deliberately coating in the NKBT film-substrate interface or in the NKBT film, i.e., BTO layers coated in sequence with NBKT layers. The BTO layer, especial coated in the NKBT film, was beneficial for crystallization process and more preferable to form a denser film morphology. The BTO-coated NKBT composite films exhibited much enhancement in electrical properties compared to the films without BTO layer. Accordingly, a high effective piezoelectric coefficient d₃₃^* of 75 pm/V and remnant polarization P_r of 22.1 μC/cm², as well as a low leakage current density of 1.2 × 10^?5 A/cm² were obtained in the 460 nm-thick composite film with BTO layers coated in the NBKT film. It meant that this kind of BTO-coated NKBT composite film could perform as a potential candidate for the lead-free piezoelectric applications. The observed enhancement in the electrical properties with the introduction of BTO layer could be mainly explained by the weakened influence of domain pinning in the film-electrode interface and grain boundaries due to the decreased strain in the film-electrode interface and better crystallinity in the highly (110)-oriented NKBT films, thereby enhancing motion of domain-walls.     

Ti6Al4V钛合金表面蓝色微弧氧化膜的制备及性能

利用微弧氧化技术在Ti6Al4V钛合金表面制备出蓝色微弧氧化膜。对微弧氧化膜的微观形貌和元素组成进行了分析,并对微弧氧化膜的显微硬度进行了测试。结果表明:微弧氧化膜表面光整,呈均匀深蓝色,其主要由Ti、Mn、O和C四种元素组成,还含有少量的V、Al和Si元素;微弧氧化膜的表面粗糙度约为0.159μm,与钛合金的表面粗糙度相近;微弧氧化膜的显微硬度为5 437.4 MPa,显著高于钛合金的显微硬度。     

Enhancing General Corrosion Resistance of Biomedical High Nitrogen Nickel-Free Stainless Steel by Nitric Acid Passivation

A systematic study of nitric acid passivation was investigated to enhance the general corrosion resistance of biomedical high-nitrogen nickel-free stainless steels(HNSs).After passivation,the corrosion rate of HNS could dramatically reduce to 1/20 of the untreated in 37℃0.9 wt% NaCl solutions.Then,the passive film on HNS was analyzed by X-ray photoelectron spectroscopy.It was found that chromium enrichment in the passive film and nitrogen enrichment in the film/metal interface contributed to the improvement in general corrosion resistance of HNS.     

Bi@Bi4Ti3O12/TiO2 films on glass with photocatalytic and self-cleaning performance

A stable and translucent Bi@Bi₄Ti₃O₁₂/TiO₂ film was fabricated on conventional glass substrates for the first time. The film exhibited a good photocatalytic performance and efficient self-cleaning capability against organic dyes under full spectral irradiation and visible light irradiation. Bi₄Ti₃O₁₂/TiO₂ film was first prepared on a glass substrate with colloidal silica as a high temperature binder, followed by implantation of nanoscale Bi in it by an in-situ partially reduction of Bi₄Ti₃O₁₂ to generate Bi@Bi₄Ti₃O₁₂/TiO₂ films. The improved photocatalytic ability is probably attributed to the surface plasmon resonance of Bi atom as well as the enhanced electron transfer efficiency and synergistic effect of Bi₄Ti₃O₁₂ and TiO₂. According to trapping experiments, hydroxyl radicals (OH) were active species in the photocatalytic degradation of dyes under full spectral light irradiation and possible photocatalytic mechanism was proposed. The film prepared in this work may well have potential practical applications in many aspects, such as cleansing treatments for high building external decorative panels and also systematic characterization of the film suggests that the in-situ reduction is an effective and simple way to produce nanoscale Bi@Bi₄Ti₃O₁₂.     

冷喷涂固态颗粒沉积中颗粒间结合形成机制研究进展

就目前主流的冷喷涂颗粒结合形成机理进行了系统总结和评述,为冷喷涂沉积体性能的调控和后续研究提供借鉴。分别就经典的颗粒界面绝热剪切失稳结合机理,颗粒界面应力波释放诱导材料射流形成结合机理,以及高速碰撞诱导颗粒表面氧化膜破碎、新鲜金属接触结合机理的基本概念、原理、特点进行了概括总结。通过大量系统文献的调研,指出现有理论目前存在的相悖和不足之处,并简要分析了现有颗粒间结合形成理论对冷喷涂沉积体质量调控方面的指导意义。最后基于现有研究的不足,对冷喷涂颗粒界面结合机制方面的研究进行了展望。     

含磷极压抗磨剂抗微点蚀性能评价和机理分析

目的 评价三种含磷极压抗磨剂的抗微点性能并分析其作用机理。方法 使用MPR模拟微点蚀试验机考察三种含磷极压抗磨剂（磷型P-1、硫磷型P-2、分散型P-3）的抗微点蚀性能。使用四球试验机、铜片腐蚀试验仪、烘箱、油膜厚度测试仪等，评价添加剂的摩擦、抗腐蚀、抗氧化性能及油膜形成能力，分析添加剂抗微点蚀性能与上述性能之间的关系。借助SEM测试分析不同添加剂的抗微点蚀机理。结果 添加P-3的润滑油GO-3的综合性能最好，GO-3具有良好的抗微点蚀性能，9 h MPR试验的辊子轨道宽度变化率为35.87%。GO-3具有良好的极压抗磨减摩性能，四球机试验测得其最大无卡咬负荷为1441.6 N，磨斑直径为0.38 mm，在试验载荷大于294 N时，其摩擦系数最低。GO-3的抗腐蚀性能良好，铜片腐蚀试验级别为1b。GO-3的氧化腐蚀性低，烘箱氧化试验中钢片评分为1分，且无油泥产生。GO-3的油膜形成能力强，60~120 ℃时弹性流体润滑油膜的厚度为371.2~153.6 nm。结论 分散型磷氮极压抗磨剂P-3化学活性适中，可以避免在摩擦表面发生严重腐蚀或剧烈摩擦化学反应，具有良好的承载、减摩、抗磨和抗微点蚀性能。     

CVD金刚石表面增透膜的研究进展

CVD金刚石膜因特有的物理化学性质，具有发展成为新一代光学材料的前景。但由于CVD金刚石膜自身局限性导致其理论透过率不到71%，在金刚石膜表面镀制增透膜，通过改变增透膜组成成分、显微组织和晶体结构，可有效地改善CVD金刚石膜自身理论透过率的问题。首先，介绍了CVD金刚石表面镀制单层增透膜增透原理，并总结了物理和化学气相沉积技术制备增透膜的优缺点。然后，重点综述了近年来CVD金刚石表面氮化物、金属氧化物和稀土金属氧化物等增透膜材料的研究进展，详细分析了增透膜制备参数、热处理工艺、衬底表面改性和掺杂工艺对增透膜整体组织和性能影响的规律。其中优化增透膜沉积温度、氧分压和热处理等工艺参数，是通过改变增透膜微观组织形貌以及晶体结构来提高其光学透过性能，而改变衬底表面结构能够通过改变增透膜与基体之间的成键方式来提升界面结合能力，而稀土元素掺杂方式是通过改变增透膜化学组成成分来改善增透膜的光学透过性能，并指出掺杂元素成型机理和影响机制。最后，展望了未来CVD金刚石表面增透膜的发展方向。     

喷丸处理对GH3535合金900℃恒温氧化行为的影响

采用不连续增重法,对喷丸状态与非喷丸状态GH3535合金900℃恒温氧化行为进行了对比研究。结果表明,900℃下,喷丸强度0.45Nmm样品与未喷丸样品相比,氧化增重降低了79.7%。未喷丸GH3535合金表面氧化产物为NiCr2O4，MoO2，NiMoO4，喷丸状态下氧化膜主要由NiO、NiFe2O4、Cr2O3和NiCr2O4组成。喷丸处理后GH3535合金表面产生塑性变形使晶粒细化,位错密度增加,在合金表层塑性变形区域的位错及晶界充当了Cr原子的快速扩散路径,增加了Cr原子扩散通量,促进Cr向表面扩散形成富Cr氧化物,使得Cr2O3层的更快形成,减少了瞬态氧化期。     

Impact of texturing on the phase transitions in sol–gel-processed Bi(Sm)FeO3 thin films on LaNiO3-buffered silicon

The orientation modulation of ferroelectric materials is a suitable method to optimize material performance. Textured Bi_1-xSm_xFeO₃ thin films (near the rhombohedral-orthorhombic (R-O) phase boundary, that is, x = 0, 0.1, 0.12, 0.14, and 0.16) were fabricated using the sol-gel process by introducing a LaNiO₃ (LNO) seed layer. Structural and ferroelectric characterizations were used to investigate the effect of texturing on the Sm doping-induced R-O phase transition of the BiFeO₃ thin films. It was found that a phase transition occurred from the rhombohedral to the orthorhombic structure with increasing Sm content in the nontextured polycrystalline films, resulting in an R-O phase boundary at x = 0.12. In contrast, the R-O phase boundary in the textured films was more diffuse, indicating a two-phase coexistence in a boarder range of Sm doping levels (x = 0.12-0.16). This discrepancy was attributed to the complexity of the stress status in thin films. The dielectric and electrical properties of the nontextured and textured samples were investigated. The current study shows that the phase boundary in ferroelectric thin films can be altered by diverse means, thus providing insights into potential applications.     

Deposition and characterization of earth abundant CuZnS ternary thin films by vacuum spray pyrolysis and fabrication of p-CZS/n-AZO heterojunction solar cells

We report fabrication of solar cell device <ITO/AZO/i-ZnO/CZS/Al> with Copper Zinc Sulfide (CZS) thin films as absorber layer. CZS thin films prepared using chemical spray pyrolysis technique at a pressure of 10⁻³ mbar at different substrate temperatures. Structural, morphological, optical, compositional and electrical properties of as prepared films are investigated. Structural analysis shows crystalline nature with mixed phase containing CuS-ZnS binary composite. Atomic Force Microscopy analysis shows the average particle size of 88 nm. Value of work function obtained from ultraviolet photoelectron spectroscopy is 4.58 eV. The band gap of the as-prepared films varies from 1.62 to 2.06 eV. Hall effect measurement proves the p-type nature for all the deposited films. Samples deposited at 350°C shows carrier concentration of 10²¹ cm⁻³ and electrical conductivity of 526 S cm⁻¹. Solar cell device structure of <ITO/AZO/i-ZnO/CZS/Al> has been fabricated using the CZS sample deposited at 350°C. The cell parameters obtained are V_oc = 0.505 V, I_sc = 4.97 mA/cm², FF = 64.28% and η = 1.6 ± 0.05%.