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931.
Lucas J. Brickweg Bryce R. Floryancic Erik D. Sapper Raymond H. Fernando 《Journal of Coatings Technology and Research》2007,4(1):107-110
Atomic Force Microscopy and Scanning Electron Microscopy were used to study shear-induced alignment of alumina and silica
nanoparticles in two-component polyurethane clear coatings. 1-D strings of nanoparticles, formed in an extended pearl-necklace
fashion were observed near the surfaces of cured films at nanoparticle volume fractions less than 0.05. This alignment is
affected by the shear conditions of the application method. When applied by spraying, linear particle strings as long as 5 cm
were observed in the direction of shear. Nanoparticle strings were also found, to a lesser extent, when coatings were applied
by a drawdown method. The phenomenon was not observed in coatings applied with minimal shear. These particle string formations,
in addition to affecting the performance of coatings, may have broader implications in the field of nanomaterials. Our literature
searches so far have not uncovered reports of stable, 1-D nanoparticle arrangements with same degree of linearity produced
under simple shear with compositions having very low particle loadings.
Presented at the 2006 FutureCoat! conference, sponsored by the Federation of Societies for Coatings Technology, in New Orleans,
LA, on November 1–3, 2006. 相似文献
932.
掺杂萘并吡喃的涂料光致变色性能研究 总被引:1,自引:0,他引:1
制备了一种能用太阳光(或紫外光)控制色彩变换的涂料。研究表明,通过光调控开关,将有机光功能材料的信息存储与显示功能在高分子载体(涂料)中得到充分展示。光调控的、智能化的新材料,使色彩变化多样,能丰富人们的生活。 相似文献
933.
The scanning electrochemical microscope (SECM) is a non-optical scanning microscopic instrument capable of imaging highly localized electrical currents associated with charge transfer reactions occurring in the vicinity of the surface of coated metals. The SECM tip operates as working microelectrode in an electrochemical cell under potentiostatic control. Microelectrode current and position is recorded as the tip is scanned very near a coated sample at a constant Z height, and variations in the faradaical current measured at selected tip potential values can be related to changes in the local concentration of electroactive species involved in corrosion reactions occurring at the substrate. Carbon steel samples coated with polyurethane in which a holiday was produced prior to immersion in different aqueous electrolytes were investigated with this technique. The release of Fe(II) ionic species into the solution phase from local anodic sites, as well as the consumption of dissolved oxygen at the corresponding cathodic locations was successfully monitored. 相似文献
935.
Powder coatings formed by flame spraying are being used in industrial applications. The resistance of plastics and their composite materials to chemicals, solvents, and atmospheric conditions and their high impact strength even at low service temperatures increase the importance of plastic and plastic‐based coatings. In this study, an ethylene vinyl alcohol copolymer powder was coated via flame spraying with gases of oxygen and acetylene. The bond strengths and microstructures of the coatings were determined with tensile testing, scanning electron microscopy, and Fourier transform infrared. The bond strengths of the coatings were determined according to ASTM C 633. Oxidizing, carburizing, and neutral flames were used. The bond strengths were lower for the oxidizing and carburizing coatings than for the neutral flame coatings. The results indicated that during the flame‐spraying process, the composition, gas, spraying distance, and coating thickness were important factors in the coating bond strength. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1357–1364, 2004 相似文献
936.
937.
938.
以锆盐和钇盐水溶液为原料,采用溶液前驱体等离子喷涂(SPPS)技术制备了氧化钇部分稳定氧化锆(7YSZ)热障涂层,利用X射线衍射仪(XRD)、拉曼光谱(Raman)和扫描电镜(SEM)研究了SPPS涂层在1 200~1 400℃下的相结构和微观结构稳定性。结果表明:沉积态SPPS涂层为亚稳四方相(t′),在1 200℃和1 300℃时未发生亚稳四方相(t′)向单斜相(m)的转变,在1 400℃热处理100h后出现了少量单斜相。在1 200~1 400℃下,SPPS涂层发生了不同程度的烧结现象;随热处理温度升高,SPPS涂层晶粒长大速率增加,在1 200、1 300和1 400℃热处理100h后,最大晶粒尺寸分别约为350、700和1 100nm。同时,在1 400℃下热处理100h后,涂层中仍然存在大量1μm的微孔,表明其具有较好的微孔保持能力。 相似文献
939.
热障涂层被广泛应用于航空发动机和燃气轮机等高温部件,其破坏机理和无损检测手段是研究中急需解决的问题。采用EB-PVD方法制备了陶瓷层厚度分别为180、120和90μm的3组热障涂层试样,经1 000℃高温氧化0、1、10、50和100h后,用HR800激光显微拉曼光谱仪测得试样表面的拉曼光谱特性,利用扫描电镜(SEM)观测了试样内部裂纹及氧化层(TGO)厚度的演变。研究表明,EB-PVD热障涂层裂纹主要发生在陶瓷层内部及陶瓷层与粘结层的界面处,粘结层和基体界面处产生裂纹的概率相对较小;同等条件下,增大陶瓷层的喷涂厚度,可以减缓氧化层的生长速度,但是会增大陶瓷层表面应力;热障涂层表面残余应力会随着热氧化时间的增加而增大,当表面残余应力减小时表明陶瓷层中有明显的裂纹或脱落产生。 相似文献
940.
为了提高药品包装用聚乙烯(PE)薄膜的阻隔性能,利用射频等离子体增强化学气相沉积技术,以氧气(O2)和六甲基二硅氧烷(HMDSO)作为氧化性气体和硅源单体,在PE薄膜表面沉积一层纳米厚度的柔性SiOx涂层。采用傅里叶变换红外吸收光谱、原子力显微镜和气体透过率测试仪对SiOx涂层的化学结构成分、表面微观形貌和气体阻隔性能进行表征。结果表明:SiOx涂层的化学结构和表面形貌对其阻隔性能有显著的影响。沉积工艺参数对SiOx涂层的阻隔性能起到了至关重要的作用。经过参数优化后制备的SiOx涂层可以有效地提高PE薄膜对氧气的阻隔性能,当射频功率为50 W,氧气和六甲基二硅氧烷的比例为2∶1,沉积气压为20Pa时制备的SiOx涂层的透氧值可从原膜的3 000mL/(m2·d)降低到30mL/(m2·d),对氧气的阻隔率可以提高100倍。 相似文献