Ultrafine nano-TiO2 loaded on dendritic porous silica nanoparticles for robust transparent antifogging self-cleaning nanocoatings

Multifunctional nanocoatings with mechanical robustness, high transparence, antifogging and self-cleaning have attracted significant attention because of their wide applications in glass-related fields. However, it is still very difficult to construct this kind of multifunctional nanocoatings due to the requirement of their comprehensive structure parameters. In this work, we successfully fabricated robust transparent antifogging self-cleaning nanocoatings by employing dendritic porous silica nanoparticles (DPSNs) evenly loaded with 2–3 nm of small TiO₂ nanoparticles (NPs) as a building block. A series of DPSNs@X% TiO₂ nanocomposites with tunable weight ratios (X%) of TiO₂/DPSNs from 10% to 60% were firstly prepared by controlling the growth of TiO₂ on the heterogeneous interface of center-radial large pores of DPSNs, followed by calcination. Noteworthily, DPSNs@10% TiO₂ exhibited highest photocatalytic and antibacterial performance mainly due to uniform distribution of TiO₂ NPs, their small sizes of 2–3 nm and center-radial pore. Therefore, DPSNs@10% TiO₂ was chosen as an optimized building block and combined with acid-catalyzed silica sol (ACSS) to develop an excellent suspension for multifunctional nanocoatings. The obtained glass slide with the optimal nanocoating showed photocatalytic self-cleaning behavior, high transparence, hydrophilic (WCA = 6.2°) antifogging, and high mechanical robustness, which can withstand 4B tape adhesion test and 3H pencil scratching test. This work provides an important exploration for developing multifunctional nanocoatings.     

层状双金属氢氧化物耐蚀材料的研究进展

层状双金属氢氧化物(LDHs)因其结构和组成的可调性、阴离子交换性等优异的物化性能,被作为腐蚀抑制剂的载体广泛应用于金属材料的防腐蚀领域。归纳总结了目前LDHs最普遍的制备方法,包括共沉淀法、水热合成法、原位生长法、旋转涂膜法以及焙烧还原法等及其优缺点。同时从LDHs材料的耐蚀机制出发,阐述了LDHs薄膜与LDHs作为填料对金属基底保护的层间阴离子交换机制,以及掺杂稀土离子、羧酸盐抑制剂、石墨烯及其衍生物、环氧富锌涂层等与LDHs的复合协同增强耐蚀机制。通过表面预处理以及化学改性制备疏水性表面可以增强耐蚀性能,分析了LDHs材料在制备与工作过程中存在的问题:LDHs制备技术不够完善,LDHs薄膜与金属基底的结合力弱,LDHs薄膜的机械性能较差,LDHs与有机聚合物难以均匀混溶等。最后展望了LDHs材料在耐蚀领域的发展方向。     

MoS2/C复合薄膜多环境摩擦学行为的研究

目的 考察不同摩擦环境（真空、PAO、不同对磨副和温度）对MoS2/C复合薄膜摩擦性能的影响,并探究其摩擦磨损机理。方法 使用直流磁控溅射技术（DCMS）和高功率脉冲磁控溅射技术（HiPIMS）在高速钢和硅基底上沉积MoS2/C复合薄膜。利用多功能摩擦试验机表征薄膜在空气、PAO、不同温度条件下的摩擦学行为。利用真空摩擦试验机表征薄膜在真空及不同对磨副条件下的摩擦性能。利用场发射扫描电子显微镜（SEM）、能谱仪（EDS）及共聚焦激光拉曼光谱仪,分析摩擦测试后,薄膜和对磨副上的形貌、磨屑成分等。结果 真空下,除氧化锆外,其他对磨副均使薄膜迅速失效。MoS2含量超过50%时,薄膜可以在真空中维持较低的摩擦系数,约为0.1。PAO环境下,边界润滑阶段摩擦系数为0.08,流体润滑阶段摩擦系数最高为0.1。随着温度从25 ℃升高至450 ℃,薄膜摩擦系数由0.09降低至0.026,450 ℃下,薄膜在700 s时失效。结论 真空下,氧化锆和氧化铝作为对磨副可以降低MoS2/C复合薄膜的粘着性,且复合薄膜中MoS2含量超过50%,可以展示出更好的摩擦性能。PAO油润滑环境下,摩擦行为主要取决于PAO的性质。高温环境下,更高的石墨化程度与MoS2再结晶可以降低薄膜的摩擦系数。     

热喷涂制备 TiO2 光催化涂层研究进展

TiO2光催化剂因其利用可持续的太阳光进行光催化反应,在环境保护、医疗卫生等领域具有潜在的应用价值,近年来引起了研究者的广泛关注。目前,颗粒状TiO2催化剂获得了一定的实际应用,但在液相中使用后需要回收,不仅增加了工艺的复杂性,而且提高了设备等成本的投入。负载型催化剂和涂层技术是将TiO2固定在载体上,可有效避免颗粒状催化剂难回收的问题。在众多涂层制备技术中,热喷涂技术可快速高效大面积地制备TiO2光催化涂层,且涂层机械性能优异,喷涂成本低廉,因而使TiO2的工业化制备和应用更具前景。综述了近年来国内外制备TiO2涂层常用的传统热喷涂技术、改进后的液相热喷涂技术和冷喷涂技术,并论述了影响TiO2光催化性能的材料相组分、涂层结构和元素掺杂等因素,总结了相应的性能改进措施,指出了目前TiO2光催化涂层的应用研究存在的问题和研究方向。     

Computer simulation of spinodal decomposition in ternary systems

The non-linear spinodal decomposition kinetics of a quenched homogeneous ternary alloy within three- or two-phase fields is modeled using a computer simulation technique formulated in the reciprocal lattice. Based on two-dimensional computer simulations, it is shown that, similar to binary alloys, spinodal decomposition in a ternary system usually produces interconnected morphologies at the very early stages of decomposition. For most of the compositions investigated, a decomposition of a homogeneous phase into three phases takes place in two stages. For some compositions, the two stages are the phase separation of an homogeneous phase into two phases, followed by further phase separation of one of the two phases into another two phases, resulting in a three-phase mixture. For other compositions, the first stage is a phase separation of an initially homogeneous phase into a two-phase mixture followed by a second stage, the appearance of a third phase along the existing interphase boundaries. This sequential phase separation in a ternary alloy can be justified from a thermodynamic stability analysis combined with the knowledge of the thermodynamic driving force for phase separation. It is also demonstrated that a third minor component strongly segregates to interphase boundaries during spinodal decomposition and subsequent coarsening of a homogeneous ternary alloy into two phases.     

铜合金垫片表面类金刚石薄膜的制备及其摩擦学性能研究

采用物理气相沉积工艺在黄铜H62垫片上制备了DLC薄膜,对DLC薄膜进行了拉曼光谱分析和截面形貌观察,测试了薄膜厚度、纳米硬度和结合力,进行了磨擦磨损试验,分析了薄膜的减摩耐磨性能.结果 表明,在H62铜合金垫片制备碳膜为DLC薄膜,薄膜总厚约2.31 μm,底层厚约0.49 μm.薄膜纳米硬度22.1GPa,薄膜与基...     

Progress in modelling of solutions

Thermodynamic modelling of solutions is reviewed based on a recent workshop at Schloss Ringberg. Although many recommendations were made, many subjects for future efforts are identified.     

Adaptive calibration and control of 2D monocular visual servo systems

For most visual servo systems, accurate camera/robot calibration is essential for precision tasks, such as tracking time-varying end-effector trajectories in the image plane of a remote (or fixed) camera. This paper presents details of control-theoretic approaches to the calibration and control of monocular visual servo systems in the case of a planar robot with a workspace perpendicular to the optical axis of the imaging system. An on-line adaptive calibration and control scheme is developed, along with an associated stability and convergence theorem. A redundancy-based refinement of this scheme is proposed and demonstrated via simulation.     

Raman scattering analysis of disorder in heterogeneous (GaAs)1−x(SiC2:H)x films grown by metal-organic chemical vapour deposition

A chemical and structural analysis of (GaAs)_1−x(SiC₂:H)_x films is performed by using the Raman scattering probe. A multizone structural model is evidenced in accordance with previous X-ray and electron diffraction experiments. The ability of a spatial correlation model to account for the lineshape evolution of the spectra of the GaAs phase is discussed for the first time for both longitudinal optical and transverse optical modes. The values of the “Raman size” of the GaAs crystallites lie well below those deduced from diffraction experiments, revealing the presence of many internal defects which greatly influence the electron-phonon interactions.     

Carbon nanotubes based high temperature vulcanized silicone rubber nanocomposite with excellent elasticity and electrical properties

In the present study, we have fabricated a series of high temperature vulcanized silicone rubber (HTVSR)/carbon nanotubes (CNTs) nanocomposites with different CNT contents. The CNTs were pretreated by the chitosan salt before being incorporated into the HTVSR. The nanocomposites were then characterized in terms of morphological, thermal, mechanical and electrical properties. It was found that the chitosan salt pretreated CNTs dispersed uniformly within the HTVSR matrix, improving the thermal and mechanical properties of the HTVSR. The nanocomposites could remain conductive without losing inherent properties after 100 times of repeated stretching/release cycles by 100%, 200%, and even 300%. Moreover, the nanocomposites had good response to the compressed pressures. The results obtained from this study indicate that the fabricated nanocomposites are potential to be used in many electrical fields such as the conductive elastomer or the pressure sensor.