空间部件表面Ti/MoS_2润滑涂层性能研究

采用中频非平衡反应磁控溅射法分别在单晶硅P(111)及钛合金基材表面制备了Ti/MoS_2复合涂层。采用原子氧辐照模拟装置考察涂层在原子氧辐照环境的抗氧化性能。利用高真空摩擦试验机分析涂层在原子氧辐照前后的摩擦学性能,并探讨了Ti掺杂对涂层的结构和摩擦学性能的影响。结果表明:Ti/MoS_2复合涂层结构致密,涂层(002)的晶粒取向使其具有低的摩擦系数。Ti元素掺杂提高了涂层的抗氧化性,摩擦产物较少使其在真空环境和原子氧辐照环境下具有优异的耐磨性能。将其用在空间部件表面可显著提高部件抗氧化能力及摩擦磨损性能,从而提高部件空间使用寿命。     

原子氧对金属银和有机防护涂层的侵蚀

用光电子能谱（XPS）和扫描电镜（SEM）观测了在模拟原子氧（AO）环境中Ag及在其表面涂覆的有机防护层的表面，研究了表面的形貌和质量损失。结果表明，AO对Ag有较严重的侵蚀作用，使原来光亮的表面失去光泽，变得粗糙，采用环氧树脂，聚胺酯或醇酸树脂作为防护涂层，AO辐照后其表面形貌也发生了较大变化，表明腐蚀严重，采用有机硅作为涂层，被AO侵蚀后其表面形貌的变化甚小，质量损失较小，表明这种涂层具有较明显的防护效果。经AO辐照后有机硅涂层表面生成致密的氧化硅膜层，对抑制AO的进一步侵蚀具有关键作用。     

氨丙基倍半硅氧烷/有机硅杂化涂层抗原子氧侵蚀

为了提高航天器用有机硅涂层的抗原子氧侵蚀性能, 用氨丙基倍半硅氧烷交联固化环氧有机硅树脂, 在聚酰亚胺基材上制备出杂化涂层, 并对杂化涂层进行了地面原子氧暴露试验, 分析了试验前后杂化涂层表面形貌、 化学成分和化学结构的变化。结果表明, 氨丙基倍半硅氧烷阻止了有机硅涂层中微裂纹的产生, 避免了“淘蚀”现象, 材料质量损失明显下降。在原子氧暴露过程中, APOSS分子中的O和Si从低的结合能态慢慢向高的结合能态(氧化态)转变, 在表面生成了SiO₂保护层, 阻止了原子氧对底层材料的进一步侵蚀。      

金属表面复合保护涂层的制备与性能研究

采用溶胶-凝胶法合成了有机-无机复合溶胶.用提拉法将复合溶胶涂覆在不锈钢基板上,基板上的湿凝胶经热处理后便形成了透明保护涂层.对制备好的涂层进行了附着力和硬度等性能分析,分析结果表明:有机-无机复合溶胶易于成膜,且成膜具有很好的耐磨性、韧性和耐腐蚀性.     

FeCrBSi/FeS层真空辐照环境下的组织结构与摩擦学性能研究

采用超音速等离子喷涂+低温离子渗硫技术在45#钢基体上制备了FeCrBSi/FeS复合涂层,考察了该复合涂层在大气、真空、原子氧辐照、紫外线辐照后的表面形貌、磨痕形貌及元素组成。利用真空摩擦磨损试验机分别完成了干摩擦条件下四种环境中的摩擦磨损性能测试。结果表明:复合FeCrBSi/FeS层经过原子氧及紫外线辐照后,有部分元素被氧化及化合物分解的现象,但并没有发生明显的材料性能改变以及润滑涂层的破坏。与45#钢相比,四种环境下该复合涂层均具有良好的润滑减摩效果。此研究表明,复合FeCrBSi/FeS层具有一定的抗原子氧和紫外线辐照的能力。     

含硅有机-无机复合涂层对铝合金的保护作用

为了改善铝合金材料的耐腐蚀性能,采用正硅酸乙酯为主要原料制备溶胶,涂覆于铝合金基体表面,经过适当处理后形成了具有有机-无机复合结构的涂层.采用电化学法、扫描电镜(SEM)等手段研究了涂层性能.结果表明,该涂层兼容了有机和无机成分的特点,涂覆试样的腐蚀电流密度可达(4.26～6.58)×10-6 A/cm2,显示涂层对于铝合金基体具有与现行的含Cr(Ⅵ)传统表面处理工艺相当的保护效果.涂层有效地减缓了铝合金在含NaCl中性水溶液中的腐蚀,能够对铝合金基体提供有效的保护.本工艺不产生有害化学物质,是一项绿色环保工艺.     

溶胶-凝胶法制备的SiO2涂层抗原子氧侵蚀性能研穷

以正硅酸乙酯（TEOS）为原料，在乙醇共溶剂和盐酸催化剂条件下，采用溶胶-凝胶方法制备SiO2胶体溶液，通过旋涂法在Kapton基体上制备了SiO2薄膜。采用自己研制的空间综合环境地面模拟设备对试样进行了原子氧暴露实验，测试表明溶胶-凝胶制备的SiO2涂层抗原子氧侵蚀性能优异，抗原子氧侵蚀性能比聚酰亚胺基体提高了2个数量级以上。经FTIR和XPS分析表明在原子氧暴露后涂层表面生成了一层SiO2，它阻止了原子氧对基体材料的进一步侵蚀。涂覆涂层后基体的光学性能没有受到影响。实验证明溶胶-凝胶制备抗原子氧侵蚀的防护涂层是一种行之有效的方法。     

有机硅微胶囊-有机硅树脂复合涂层对空间 K apton的原子氧防护

将采用水相分离法制备的以明胶为囊壁、有机硅为囊芯的微胶囊与有机硅树脂乳液在一定条件下混合,在聚酰亚胺薄膜(Kapton)基材表面制备出含有机硅树脂的微胶囊-有机硅复合涂层,并将所制备的涂层分别进行原子氧暴露试验。结果表明,原子氧对Kapton侵蚀严重,质量损失严重,由原来光滑平整的表面变为凹凸不平的地毯状,太阳光吸收率变化值Δα为0. 272。微胶囊2有机硅复合涂层对Kapton基体优良的保护作用,使试样的质量损失和剥蚀率明显下降,且Δα仅为 0.071。尤其是微胶囊与有机硅质量比为1∶5的涂层,质量损失为Kapton试样的2.3%。     

SiO_2对MoS_2/酚醛环氧树脂涂层原子氧辐照前后组成与性能的影响

为了有效降低低轨道原子氧辐照对黏结固体润滑涂层摩擦学性能的影响,满足航天器机械运动机构对空间润滑材料高可靠、长寿命的要求,在MoS_2/酚醛环氧树脂涂层中添加六甲基二硅胺烷修饰的SiO_2,制备了复合涂层,并用原子氧地面模拟装置进行辐照.分别采用X射线光电子能谱(XPS)、CSM摩擦磨损试验及扫描电子显微镜(SEM)分析了涂层原子氧辐照前后的化学组成、摩擦磨损性能及磨痕形貌.结果表明:添加SiO_2在一定程度上提高了MoS_2/酚醛环氧树脂涂层的抗原子氧剥蚀和摩擦磨损性能;添加2%SiO_2的涂层在原子氧辐照前后摩擦系数最低,耐磨性能最佳;当SiO_2添加量为1%时,涂层辐照前后的耐磨寿命最长.     

耐原子氧聚酰亚胺材料的研究进展

自21世纪以来,航空航天方面的快速发展为人类日常通信、观察天文气相、探索宇宙等提供了重要的技术支持手段.其中,聚酰亚胺(PI)凭借其优异的耐高低温性能、力学性能、耐辐射性、电性能、耐溶剂性等成为不可或缺的航天器材料之一,且被广泛用作航天器的太阳电池阵列的柔性基板、多层热绝缘毯和电路系统的绝缘保护层.然而,航天器长期工作于低地球轨道,这一特殊环境中的原子氧(AO)具有高通量和强氧化性,它会快速侵蚀航天器表面的主要热控材料PI,使其光学、电学、力学等重要性能退化,从而导致航天器工作效率下降、使用寿命缩短、系统目标设计失败,严重阻碍航天事业的发展.多年来,针对上述问题,研究人员提出了多种解决办法并已取得较大进展.其中,在材料表面施加防护涂层已发展成为既能保护基材不受原子氧剥蚀、又能保持基底材料原有性能的方法,其适用于多种表面制作,工艺简单,应用广泛;而在耐原子氧聚酰亚胺新型材料方面,科研人员也克服困难,开发出性能更为优异、使用寿命更长的新材料.另外,由于特殊试验条件的限制,促使耐原子氧地面模拟实验发展迅猛,目前已提出多种模拟理论,并制造模拟器以辅助研究.本文对比了目前已商业化应用的聚酰亚胺材料的耐原子氧性能,介绍了耐原子氧的地面模拟试验方法的原理和分类,总结了耐原子氧聚酰亚胺材料的类别,包括防护涂层法和新型方法制备的耐原子氧聚酰亚胺材料,并对各种不同类型防护方法的优缺点进行了合理评判,指出耐原子氧聚酰亚胺材料的未来发展方向及应用前景.     

醇硅比对太阳能玻璃用多孔SiO2减反膜性能的影响

采用溶胶-凝胶工艺在碱催化条件下制备了多孔结构的纳米SiO2薄膜,研究了不同醇硅比对溶胶体系的粒度分布、薄膜折射率以及透过率的影响。用纳米粒度分析仪测试了溶胶的颗粒分布,用紫外-可见-近红外分光光度计、椭偏仪、原子力显微镜(AFM)、扫描电子显微镜(SEM)测试了薄膜的光学性能、折射率、膜厚和显微形貌等。结果表明:随着醇硅比的增大,溶胶体系粘度下降,凝胶时间延长,颗粒度下降,折射率有升高的趋势;制备的增透玻璃膜层折射率为1.24,可见光透过率达到98.22%。     

Perhydropolysilazane derived silica coating protecting Kapton from atomic oxygen attack

By using surface sol-gel method with perhydropolysilazane (PHPS) as a precursor, a silica coating was prepared on a Kapton substrate as an atomic oxygen (AO) protective coating. The AO exposure tests were conducted in a ground-based simulator. It is found that the erosion yield of Kapton decreases by about three orders of magnitude after the superficial application of the coating. After AO exposure, the surface of the coating is smooth and uniform, no surface shrinkage induced cracks or undercutting erosion are observed. This is because that during AO exposure the PHPS is oxidized directly to form SiO₂ without through intermediate reaction processes, the surface shrinkage and cracking tendency are prohibited. Meanwhile, this PHPS derived silica coating also presents self-healing effect due to the oxidation of free Si. Compared with other kinds of silica or organic polymer coatings, this PHPS derived silica coating exhibits a superior AO erosion resistance.     

Biological characterization of a new silicon based coating developed for dental implants

Taking into account the influence of Si in osteoblast cell proliferation, a series of sol–gel derived silicon based coating was prepared by controlling the process parameters and varying the different Si-alkoxide precursors molar rate in order to obtain materials able to release Si compounds. For this purpose, methyltrimethoxysilane (MTMOS) and tetraethyl orthosilicate (TEOS) were hydrolysed together and the sol obtained was used to dip-coat the different substrates. The silicon release ability of the coatings was tested finding that it was dependent on the TEOS precursor content, reaching a Si amount value around ninefolds higher for coatings with TEOS than for the pure MTMOS material. To test the effect of this released Si, the in vitro performance of developed coatings was tested with human adipose mesenchymal stem cells finding a significantly higher proliferation and mineralization on the coating with the higher TEOS content. For in vivo evaluation of the biocompatibility, coated implants were placed in the tibia of the rabbit and a histological analysis was performed. The evaluation of parameters such as the bone marrow state, the presence of giant cells and the fibrous capsule proved the biocompatibility of the developed coatings. Furthermore, coated implants seemed to produce a qualitatively higher osteoblastic activity and a higher number of bone spicules than the control (uncoated commercial SLA titanium dental implant).     

Preparation of sol–gel-based nanostructured hybrid coatings; part 1: morphological and mechanical studies

Attempts have been made using sol–gel-based precursors to produce hybrid organic–inorganic clearcoats. To this end, a typical automotive acrylic/melamine clearcoat with tetramethyl ortosilicate (TEOS) and methacryoloxy propyltrimethoxysilane (MEMO) were used to obtain nanostructured silica clusters produced in situ embedded in the polymeric matrix. Microscopic techniques including scanning electron microscope (SEM), atomic force microscope (AFM), and transmission electron microscope (TEM) were utilized to investigate the morphology of coatings. The effect of each precursor on coating mechanical properties was also studied using dynamic mechanical thermal analysis (DMTA) as well as micro and nanoindentation techniques. It was found that using TEOS and MEMO (in non-hydrolyzed state), the mechanical properties of the resulting films were negatively influenced. The decreased hardness, lower T _g and cross-linking density, and reduced elastic modulus were observed with non-hydrolyzed precursors. In addition, the phase separation of organic and inorganic domains occurred in the presence of pristine sol–gel precursors. However, using hydrolyzed precursors (HTEOS and HMEMO), the mechanical properties were notably improved. While HTEOS resulted in an increase in coating T _g, and cross-linking density as well as improved elastic modulus and hardness, HMEMO caused an increase in coating hardness but lowered coating T _g and cross-linking density.     

Investigations into sol-gel silica and silica hybrid coatings for dielectromagnetic soft magnetic composite applications

A series of inorganic and organic–inorganic hybrid silica coatings were synthesised by a sol-gel process from tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) precursors, and used to investigate their effectiveness as insulation materials in dielectromagnetic soft magnetic composites. The coating materials and coated iron powders were analysed by FTIR, electron and atomic force microscopy. Results showed that introduction of the organic phase imparted desirable hydrophobicity and flexibility to the coating, whilst still providing effective electrical insulation at temperatures up to 500 °C. The hybrid coatings covered the iron particle surface very effectively and formed continuous coatings that could remain intact even after compaction at pressures up to 900 MPa, depending on the coating amount. Initial magnetic characterisations are also encouraging. As a result, such hybrid-coated iron powders can be considered suitable candidates as heat-treatable high-performance dielectromagnetics.     

Effects of Vacuum Ultraviolet Radiation on Atomic Oxygen Erosion of Polysiloxane/SiO2 Hybrid Coatings

Polysiloxane/SiO2 hybrid coatings have been prepared on Kapton films by a sol-gel process.The erosion resistance of polysiloxane/SiO2(20 wt pct) coating was evaluated by exposure tests of vacuum ultraviolet radiation(VUV) and atomic oxygen beam(AO) in a ground-based simulation facility.The experimental results indicate that this coating exhibits better AO resistance than pure polysiloxane coating.The erosion yield(Ey) of the polysiloxane/SiO2(20 wt pct) hybrid coating is about 10-27 cm3/atom,being one or tw...     

具有自洁和耐磨功能SiO2/TiO2减反膜的制备与研究

以正硅酸乙酯(TEOS)和钛酸正丁酯(TBOT)为原料,采用溶胶-凝胶法制备了SiO2溶胶和TiO2溶胶,利用浸渍提拉法制备了SiO2/TiO2双层减反膜.用紫外-可见分光光度计(UV-Vis)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、原子力显微镜(AFM)、椭圆偏振光谱仪和接触角测量仪等分析表征了薄膜的特性,以光催化降解甲基橙溶液实验来评价薄膜的自洁功能,考察了SiO2/TiO2双层减反膜的耐磨擦性.结果表明,SiO2/TiO2双层减反膜在400~800nm可见光波段的透光率最高可达97.2%,薄膜表面平整,结构致密且粗糙度小,经紫外灯照射后薄膜的水接触角接近0°,光催化2h后可将5mg/L的甲基橙溶液降解43.6%.SiO2/TiO2减反膜还具有优良的耐磨擦性能.     

正硅酸乙酯为无机组分前驱体的聚碳酸酯耐磨涂层

以正硅酸乙酯(TEOS)作为无机组分的前驱体,甲基三甲氧基硅烷(MTMS)水解聚合产物作为有机组分,通过溶胶-凝胶法在聚碳酸酯(PC)表面形成耐磨涂层。红外光谱分析表明该涂层具有Si—O—Si的交联网络结构。研究了MTMS和TEOS的摩尔比对涂层的光学性能、硬度、附着力和耐磨性能的影响。结果表明,当MTMS和TEOS的摩尔比为2∶1时,涂层的综合性能达到最优,该涂层在经历500次耐磨试验后的雾度为12.69%,而纯PC的雾度增至42.38%。采用SEM和TEM分析了MTMS/TEOS具有优异耐磨性能的原因在于该涂层具有纳米SiO2粒子分散于有机基体的微观结构。