有机硅改性聚酰亚胺复合膜的抗原子氧性能研究

由端氨丙基聚二甲基硅氧烷（PDMS）、均苯四甲酸二酐（PMDA）和4,4’-二氨基二苯醚（ODA）在N,N’-二甲基乙酰胺（DMAc）中共聚,热亚胺化法制备有机硅改性聚酰亚胺复合膜。通过傅立叶变换红外吸收光谱仪（FTIR）、X射线光电子能谱（XPS）分析材料的化学结构,采用扫描电子显微镜（SEM）观察材料的表观形貌,利用地面原子氧（AO）模拟设备研究了该复合膜的抗原子氧性能。结果表明有机硅改性聚酰亚胺复合膜在AO累积通量达到2.06?020atom/cm2时,复合膜的AO剥蚀率可以达到6.69?0-25 cm3/atom,约是纯聚酰亚胺薄膜抗原子氧性能的4.5倍。     

正交试验法优化聚酰亚胺表面喷涂有机硅涂层的工艺参数

为了实现太阳能电池基板对原子氧的防护功能,以涂层表观形貌、最低厚度和厚度一致性作为质量评价指标,通过正交试验考察了几个主要的喷涂工艺参数对在聚酰亚胺表面制备有机硅涂层的影响。结果表明,喷嘴运行速率越快,涂层越薄;行间距越小,涂层厚度越均匀;空气压力越高,涂层表观形貌越好,但厚度一致性越差。经过第二次正交试验验证,得出优化的工艺参数为:喷嘴运行速率70～130 mm/s,雾化压力0.36～0.54 MPa,空气压力0.24～0.33 MPa,喷涂距离140～200 mm,行间距18～21 mm。在上述条件下可制得厚度为40～140μm的合格涂层。     

有机硅改性聚酰亚胺复合膜的抗原子氧性能

由端氨丙基聚二甲基硅氧烷(PDMS)、均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)在N,N′-二甲基乙酰胺(DMAc)中共聚,热亚胺化法制备一系列有机硅改性聚酰亚胺复合材料。通过傅里叶变换红外吸收光谱仪(FTIR)、X射线光电子能谱(XPS)分析材料的化学结构,采用扫描电子显微镜(SEM)观察材料的表观形貌,利用地面原子氧(AO)模拟设备研究了该复合膜的抗原子氧性能。结果表明,有机硅改性聚酰亚胺复合膜在AO累积通量达到2.06×1020atom/cm2时,复合膜的AO剥蚀率可以达到6.69×10-25cm3/atom,约是纯聚酰亚胺薄膜抗原子氧性能的4.5倍。     

柱段结构产品自动喷涂有机硅涂层的影响因素分析

通过立式喷涂生产线考察了航空用柱段结构产品自动喷涂有机硅涂层时的工艺参数。结果表明,喷涂压力为0.4～0.6 MPa,涂料流量为500～600 mL/min,喷涂距离为200～220 mm,喷枪摆动角度为45°～50°时,所得涂层厚度均匀,外观质量较好。     

影响有机硅热防护涂层的热导率的因素

以硅树脂为基料,配合中空玻璃微球等填料,制备了有机硅热防护涂层;研究了填料的组合、添加量、规格以及溶剂体系等对有机硅热防护涂层热导率的影响。结果表明,采用表面经过处理的中空玻璃微球和气相法白炭黑A380的组合填料、中空玻璃微球的用量选择60份、并使用酮类溶剂和芳香类溶剂的混合溶剂制成的热防护涂层,其热导率≤0·1W/(m·K),密度≤0·55g/cm3,拉伸强度≥2·0MPa。     

织物用有机硅涂层剂研究新进展

简要介绍了有机硅涂层剂的特性,着重阐述了近年来新研发的织物用有机硅涂层剂的制备方法及应用,指出了今后有机硅涂层剂的研究方向。     

喷涂聚脲与聚氨酯防护涂层的自然环境老化性能研究

采用海洋大气环境户外自然曝晒的方法,研究了喷涂聚脲涂层(QF-162涂层)和喷涂聚氨酯涂层(QF-178涂层)的力学性能、分子内部结构的变化。结果表明:经过自然曝晒2 493 d后,QF-162涂层颜色变化明显,失光率为86.84%,拉伸强度下降29.37%,断裂伸长率下降14.38%; QF-178涂层颜色变化十分显著,失光率达89.63%,拉伸强度下降90.71%,断裂伸长率下降98.75%。FT-IR微观测试结果表明:在经过2 493 d的户外自然曝晒后,QF-162涂层只有涂层表面分子的化学键出现了断键,分子内部结构变化不大;而QF-178涂层分子内部结构发生显著的变化,分子的化学键几乎全部断裂,涂层完全失去了使用价值。     

电弧喷涂与粉末涂料喷涂复合涂层防护技术

研究了热固性粉末涂料用作金属热喷涂涂层的封闭层及面层的防护技术,比较了分别喷涂环氧锌基重防腐粉末涂料、纯聚酯粉末涂料,喷涂环氧锌基重防腐粉末涂料后再喷涂纯聚酯粉末涂料以及热浸镀锌后喷涂纯聚酯粉末涂料等试样在不同盐雾和人工加速老化时间下的附着力.结果发现,只有熔融黏度偏低的环氧类粉末涂料适合用作封闭层.该复合涂层技术已应用于高速公路护栏上.     

航天材料的抗原子氧防护技术研究进展

在低地球轨道环境中,航天器表面材料受到侵蚀最为严重.介绍了原子氧对航天用材料的侵蚀情况,并且阐述了近些年来研究人员对原子氧侵蚀的多种防护措施及效果,包括涂层型抗原子氧侵蚀材料、本征型抗原子氧侵蚀材料、添加型抗原子氧侵蚀材料、界面自组装等.     

粉末静电喷涂涂层产生针孔的原因和排除

介绍了涂层表面针孔出现的几种原因，包括粉末、底部锈蚀、磷化和酸洗、磷化残液、深度划伤等，说明针孔是由涂层内部或底部产生的气体造成的，图示了这些气体产生的部位；根据针孔产生的不同原因，给出各自的解决办法，同时图示了一种工件边缘针孔的综合解决方案。     

有机硅硬质涂料的涂装工艺与效果

分析了有机硅硬质涂料作聚甲基丙烯酸甲酯(PMMA)树脂光学镜片的表面增硬剂时，涂装工艺对PMMA树脂光学镜片各项性能的影响。给出了适宜的涂装工艺：涂装室的室温18～22℃、相对湿度45％～55％；PMMA树脂光学镜片浸渍涂覆的提升速度25cm／min；涂覆后预固化温度30-50℃、预固化时间10～20min，固化温度80～90℃、固化时间2～3h。采用该涂装工艺涂装有机硅硬质涂料后，PMMA树脂光学镜片上涂膜的厚度为3～4μm，镜片表面的铅笔硬度由2H提高到6H，且其耐热、耐温水、耐溶剂等性能得到改善。     

甲基氯硅烷生产过程中的污染防治对策

简述了国内有机硅市场状况，系统分析了甲基氯硅烷生产过程中污染物的产生环节、污染物的种类和数量，并据此提出了相应的污染防治措施。     

High performance reaction-induced quasi-ceramic silicone conversion coating for corrosion protection of aluminium alloys

Regulations posed by the Environmental Protection Agency on the use of chromate conversion coatings have triggered the need to find alternative materials for the corrosion protection of aluminium and its alloys. A simple four-step process of creating a quasi-ceramic coating has been developed. The coating, which is made of environmentally safe chemicals, should be easily and safely manufactured for bulk production. Here, we describe the synthesis, characterization and evaluation of a silicone conversion coating for aluminium metal and its alloys. The spectroscopic techniques utilised in this study have shown the mode of the bonding mechanism between the metal and the coating. Thermal analysis of the material was conducted to evaluate its stability, while nano-mechanical properties were determined and correlated with the surface morphology of the coating. Results obtained from FTIR and XPS spectroscopic techniques suggested that the coating adhered to the metal substrates through active surface functionalities, and thermal analysis showed that the coatings contained volatile solvents including water that evaporated at lower temperatures. Nano-mechanical tests suggested that the coating had elastic properties. Accelerated corrosion and immersion tests were also performed on coated and uncoated aluminium alloys. Coated and uncoated aluminium alloys were also exposed to soil containing sulphate-reducing bacteria. Coated coupons showed excellent corrosion protection and antifouling characteristics indicating that the coatings were impervious and of high integrity.     

Antiadhesion elastomer seal coatings for UV and atomic oxygen protection

Radiation blocking sunscreen coatings have been developed for the protection of elastomer seals used in low‐Earth‐orbit (LEO). The coatings protect the seals from ultraviolet (UV) radiation and atomic oxygen (AO) damage. The coatings were developed for use on NASA docking seals. Docking seal damage from the UV and AO present in LEO can constrain mission time‐line, flight mode options, and increases risk. A low level of adhesion is also required for docking seals so undocking push‐off forces can be low. The coatings presented also mitigate this unwanted adhesion. Greases with low collected volatile condensable materials (CVCM) and low total mass loss (TML) were mixed with slippery and/or UV blocking powders to create the protective coatings. Coatings were applied at rates up to 2 mg/cm². Coated seals were exposed to AO and UV in the NUV (near‐UV) and UV‐C wavelength ranges (300 to 400 nm and 254 nm, respectively). Ground based ashers were used to simulate the AO of space. The Sun's UV energy was mimicked assuming a nose forward flight mode, resulting in an exposure rate of 2.5 MJ/m² day. Exposures between 0 and 147 MJ/m² (UV‐C) and 245 MJ/m² (NUV) were accomplished. The protective coatings were durable, providing protection from UV after a simulated docking and undocking cycle. The level of protection begins to decline at coverage rates less than 0.9 mg/cm². The leakage of seals coated with Braycote + 20%Z‐cote ZnO sunscreen increased by a factor of 40 after moderate AO exposure; indicating that this coating might not be suitable due to AO intolerance. Seals coated with DC‐7–16.4%Z‐cote ZnO sunscreen were not significantly affected by combined doses of 2 × 10²¹ atoms/cm² AO with 73 MJ/m² UV‐C. Unprotected seals were significantly damaged at UV‐C exposures of 0.3 MJ/m² and DC‐7–16.4%Z‐cote coated seals were undamaged at all exposures up to the limits tested thus far which were 147 MJ/m² UV‐C and 245 MJ/m² NUV. The coatings decreased adhesion sufficiently for docking seals at temperatures equal to or greater than ?8°C thus offer a simple and inexpensive way to mitigate adhesion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41662.     

Influences of silicone emulsion on fire protection of waterborne intumescent fire-resistive coating

The combination of self-crosslinking polyacrylate emulsion and silicone emulsion was used as a binder for the preparation of waterborne intumescent fire-resistive coatings. The influences of silicone emulsion on fire protection and char formation of the coatings were investigated in detail by means of TGA, SEM, energy dispersive spectroscopy analysis, rheological measurement, and fire protection tests. The results showed that using silicone emulsion improved thermal stability and antioxidation ability of the coating and increased the residue weights of the char layer at high temperature. Furthermore, an appropriate amount of silicone emulsion could improve the rheological property of the mixed binders and be conducive to the increase of the intumescent factor of the coatings, thus improving the fire protection of the coating significantly. However, an excess amount of silicone emulsion can lead to uneven dispersion of silicone emulsion in the mixed binder and cause an uneven distribution of cell size of the char layer.     

Highly branched phenolic resin-grafted silicone rubber copolymer for high efficiency ablation thermal protection coating

Highly branched phenolic resin-grafted silicone rubber (PGS) was synthesized by grafting allyl ether phenolic resin onto silicone rubber with Si─H groups via hydrosilylation. The chemical structure of the copolymer was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and gel permeation chromatography, and its microphase morphology was observed via scanning electron microscopy (SEM). The mechanical properties and thermal stability of the material were also characterized. Thereafter, an ablation thermal protection coating (ATPC) based on PGS as the polymer matrix was prepared. In comparison with silicone rubber-based ATPC, the PGS-based ATPC showed better thermal stability and a stronger char layer. After oxygen–acetylene testing, the micromorphology and chemical composition of the PGS-based ATPC were characterized via SEM, energy-dispersive spectrometry, and X-ray diffraction. Finally, the PGS- and silicone rubber-based ATPCs were subjected to a heat flow of 370 kW m⁻² for 70 s, the background temperature of the PGS-based ATPC was only 70 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48353.     

Evaluation of two new white silicone thermal control paints under atomic oxygen

The exterior optical surfaces of satellites are directly exposed to the harsh space environment. Thermal control paints are resistant to the conditions encountered at low earth orbit (LEO): vacuum, atomic oxygen, thermal cycling, and ultraviolet radiation. In this paper two white paints were prepared by ultrasonic dispersing method for application to space structures. The white paints include zinc-oxide-pigmented silicone elastomer SilGel 612 (U1) and a zinc-oxide-pigmented silicone elastomer RT604 (U2). These coatings are electrically non-conductive. We present the behavior of thermal control paints under atomic oxygen (AO). The effects of AO exposure were studied by the mass loss of paint specimens and complementary techniques including scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also the optical degradation in the reflectance spectra, solar absorptance and thermal emittance for U1 and U2 samples before and after AO exposure were investigated. The paints have promising AO resistance properties that could be suitable for space applications.     

有机硅硬质涂料的制备

以甲基三乙氧基硅烷和正硅酸乙酯为主要原料，经水解缩合，制得低n(R)／n(Si)值的硅树脂；添加适当的溶剂、固化剂和改性剂等助剂，制得有机硅硬质涂料。讨论了原料配比、溶剂及各种助剂对有机硅硬质涂料性能的影响。结果表明，硅树脂的n(R)／n(Si)值选择0、85，以甲醇／乙醇／异丙醇／乙二醇甲醚为复合溶剂、氨基树脂为耐碱改性剂、三乙酰丙酮铝为固化剂时，制成的有机硅硬质涂料贮存期超过6个月，固化速度快，涂膜硬度高达6H，对有机玻璃的附着力为1级，透光度93．6％，耐碱性良好。     

Scaling-up of the electrodeposition process of nano-composite coating for corrosion and wear protection

The codeposition of hard nanoparticles into metal matrix electrodeposits usually leads to the increase of the coating hardness and abrasion resistance and causes a change to the microstructure of the deposits leading to more compact, nanostructured coatings with an increased corrosion resistance. Very often the laboratory scale results are not easily transferable to an industrial scale due to the introduction of new process variables such as the geometry and the dimensions of the component to coat.The aim of the present work was the study, in laboratory scale, of nano-composite nickel matrix coatings containing SiC nanoparticles and the transfer of this technology in industrial scale. The deposits have been produced using a Watts type bath containing 20 g/l of nanoparticles, under galvanostatic conditions using a current density of 2 A/dm². The deposits have been studied regarding their microstructure, abrasion and corrosion resistance. Based on the satisfactory results of the laboratory tests, the second part of this work contains the scaling-up and the industrialization of the process and the electrodeposition of the composite coating on ship propeller models and profiles as well as on train axles. The prototype parts were tested under actual working conditions.     

有机硅绝热涂料的研制

用RTV585硅橡胶、填料及固化剂60R制成了绝热涂料；考察了填料种类及用量对绝热涂料绝热性能、力学性能和粘接性能的影响及金属表面处理方式对金属与涂料的粘接性能的影响。结果表明，当RTV585用量为100g、固化剂60R用量为2g、软木粉用量为20g时，可制得绝热性能良好的涂料；采用喷砂 清洗 偶联剂的表面处理模式，可大大提高涂料与金属的粘接性能。