Papers by Keyword: Surface Treatment

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Authors: Zoltán Balogh-Michels, Alexander Faeht, Simon Kleiner, Patrick Margraf, Alex Dommann, Antonia Neels
Abstract: In this work we show our result of in-situ nitrocarburizing and nitriding treatments AISI316L specimens. Part of the samples have been depassivated ex-situ and coated with a Ni layer, while other specimens received in-situ depassivation. Processing was carried out in a custom built reaction chamber attached to a Bruker D8 Advance diffractometer. We monitored the 111 peak of both the base material and expanded austenite. From the shrinkage of the base material peak the total thickness of the expanded austenite can be determined. Applying both N and C resulted in a more than 10 times faster growth of the expanded austenite than with N only. The growth is thermally activated. The activation energy for nitrocarburizing is 164 kJ/mol. This is in agreement with the activation energy of the diffusion of interstitials. Detailed analysis of the expanded austenite peak allowed the derivation of a “master curve” for the composition depth profile. This suggest that two interacting process controls the evolution. The width of the reaction zone is limited by the diffusion at low concentration side. The total concentration is determined by the reaction at the interface.
Authors: Yu Bai, Fang Li Yu, Jun Du, Wen Xian Wang, Ze Qin Cui, Zhi Hai Han, Jian Feng Yang
Abstract: Due to the low density and high specific strength, magnesium and its alloys have been extensively used in the automobile and aerospace applications, where the weight reduction is critical. However, they are highly prone to corrosion, which has greatly limited their application in the automotive and aerospace industries. This paper briefly reviews the technologies for improving the corrosion and wear resistance of magnesium alloys and finds that the widespread application of magnesium alloys is still limited by the lack of proper protective coatings. Therefore, there is still a need to explore new materials and methods for the effective protection of magnesium and its alloys.
Authors: Byeoung Ku Kim, Young Seak Lee, Seung Kon Ryu, Byung Joo Kim, Soo Jin Park
Abstract: In this work, to introduce polar functional groups on carbon surfaces, activated carbon fibers (ACFs) were treated by nitric acid in order to enhance the adsorption capacity of propylamine which was one of toxic gases in cigarette smoke. It was found that the polar functional groups were predominantly increased up to 2.0 M of nitric acid, resulting in the increase of total surface acidity. It was found that the adsorption amount of propylamine of the modified ACFs was increased around 17% after a nitric acid treatment. From the XPS results, it was observed that propylamine was reacted with strong or weak polar (acidic) groups, such as COOH, -COO or OH existed on the ACF surfaces.
Authors: M.H. Kim, Kyong Yop Rhee, Young Nam Paik, S.H. Ryu
Abstract: For a present study, the surfaces of graphite/epoxy prepregs were modified using plasma treatment to improve the delamination resistance behavior of graphite/epoxy laminated composites. The optimal treatment time was determined by measuring the change of contact angle with treatment time. Unidirectional DCB (double cantilever beam) specimens were used in the mode I delamination fracture tests. The delamination resistance curve of regular (untreated) specimen was compared with that of plasma-treated specimen in order to determine the effect of prepreg treatment on the resistance behavior. It was found that contact angle was changed from ~64° to ~47° depending on the treatment time. The contact angle was a minimum for a 30 min treatment time. It was also found that delamination resistance behavior of graphite/epoxy composites was improved about 20%.
Authors: Je Wook Chae, Sung Bae Lee, Chan Lee, Hyun Jun Kim, Young Shin Lee
Abstract: This paper includes a study on the surface treatments of the barrel of small arms with an aim at improving resistance of corrosion and wear. The inner surface of the barrel is Cr plated or nitrided to improve the performance under the firing. The endurance test was conducted to compare the wear resistance of standard barrel (the non surface treatment barrel), the Cr plating barrel and the nitriding barrel. The wear resistance is evaluated by inner diameter of the barrel, muzzle velocity and dispersion during the firing. And the salt water immersion test was conducted to estimate the corrosion resistance. As the results of the tests, the Cr plating barrel is superior to the NST barrel and the nitriding barrel in a view of corrosion and wear.
Authors: Da Song He, Cun Ping Liu, Sheng Guo, Xiu Ying Li
Abstract: The enhancement effect of using PAN-based carbon fibers surface modified by ammonium nitrate for removing SO2 and H2S in moist air at room temperature was characterized and investigated. The pore structure of the samples so prepared was examined by adsorption measurement. Surface groups introduced by treatment with ammonium nitrate was assessed by xray photoelectron spectroscopy. The results show that the amount of sulfur dioxide and hydrogen sulfide adsorbed with the treated carbon fibers are increased by 112% and 93% and ammonium nitrate treatment improved original carbon fibers adsorption performance, not only by introducing nitrogen surface groups, but also by extending the surface area.
Authors: N.S. Zhu, S.N. Ma, C.H. Hu
Abstract: Low temperature ammonia plasma surface treatment on asphalt base carbon fiber is reported with 150°C for 60min, 200°C for 60min and without treatment. The surface topography, chemical composition and structural changes were followed by Atomic force microscope(AFM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, of which indicate the treatment could improve the density of carbonyl and amino functional group on the surface of carbon fiber, which can also changed carbon crystalline structure. The density of carbonyl and amino functional group was shown higher for the fibers treated at 150°C than for the fibers treated at 200°C which could be attributed to the temperature and introduced Si element factors.
Authors: Fabíola Ottoboni Yamane, Mara Lucy Aparecida da Silva, Dener Israel França, Murilo Vichietti Mantuvanelli, Daniel Thomazini, Maria Virgínia Gelfuso
Abstract: The coconut fibers are an abundant source of natural materials, renewable, high-availability, accessibility and biodegradable. This great interest in developing and using materials made from renewable sources occurred mainly in response to the global attention for the use of natural products and the preservation of the environment. In this paper, coconut fibers received different surface treatments, environmentally friendly, based on high values of temperature and pressure. The coconut fibers were characterized by FTIR, SEM, water absorption, weight loss and wetting angle. The results indicated that the methods were effective, changing the chemical composition of the fiber as well as their surface morphology and raising the hydrophobic character. Thus, the compatibility between the fiber and the polymeric matrix should be increased, providing the application of these new fibers in the development of composite materials.
Authors: Feng Jie Yan, Xin Geng Li, Zeng Wu Yue, Xue Gang Wang, Kai Guo
Abstract: Galvanized steel, a general grounding material, has a short service life due to high corrosion rate in alkaline soil environment. An Al-4.5Cu-Re alloy was developed to overcome the shortcoming of galvanized steel. The properties of Al-4.5Cu-Re alloy were studied by accelerated corrosion test, grounding resistance test, electrochemical test and comprehensive electrical performance test in alkaline soil. The results show that the Al-Cu alloy with shot blasting and pre-oxidation exhibited low grounding resistance, high corrosion resistance, good comprehensive electrical performance and environment friendly feature. Al-Cu alloy with shot blasting and pre-oxidation can be used as grounding material.
Authors: Woo Tai Jung, Moon Seoung Keum, Jae Yoon Kang, Jong Sup Park
Abstract: This study evaluates the bond performance of the CFRP tendon through pull-out test and investigates experimentally the strengthening performance according to the eventual surface treatment of the tendon on concrete beams strengthened by near-surface mounted (NSM) tendon. The pull-out test revealed that the bond strength was improved by 3 times when surface treatment was applied to the tendon. In addition, similar improvement of the bond performances was observed regardless of the execution time of the surface treatment being manually on site or at the factory during the production of the tendon. The flexural test showed that the surface treatment of the CFRP tendon improved the strengthening performance by 13%. Consequently, when using the CFRP tendon featured by low bond strength, it appears that structural reinforcement can be improved by executing beforehand surface treatment of the tendon on site.
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