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101.
This article deals with the modeling and simulation of the vibration behavior of piezoelectric micro‐cantilever (MC) based on the Timoshenko theory and using multi‐scale (MTS) method in the air environment. In this regard, the results are compared with the previous literature, such as the finite element method and the MTS method. The analysis of the piezoelectric MC vibrating behavior is investigated in a dynamical mode including non‐contact and tapping modes. The dynamics of this system is affected by interferential forces between probe tip and sample surface, such as van der Waals, capillary, and contact forces. According to the results, the forces applied to the probe tip reduce the amplitude and the resonance frequency. The simulation of surface topography in non‐contact mode and tapping for rectangular and wedge‐shaped roughness in the air environment are presented. Various experiments have been conducted in Ara research Company using the atomic force microscopy device in the amplitude mode. In the NSC15 Cantilever, the first natural frequency is derived from the results of the MC simulation based on Timoshenko beam theory, the practical results are 295.85 and 296.12 kHz, and the error rate is 0.09; at higher natural frequencies, the error rate has been increased. The γ f coefficient is a measure of the nonlinear effects on the system; the effect of the piezoelectric length and width on γ f coefficient is also investigated. 相似文献
102.
Effect of chitosan–oil coating on qualitative properties of sweet pepper (Capsicum annuum L.) stored at 8 °C for 35 days was investigated. The chitosan–oil coating treatment exhibited the best control effect on decay (below 5%). At the end of storage, samples treated with chitosan-oil coatings maintained good sensory acceptability, whereas the sensory quality of control samples became unacceptable. The higher activities of scavenger antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), in treated peppers at the 35th day should be contributed to the chitosan–oil coating. Malondialdehyde (MDA) and electrolyte leakage contents in chitosan–oil-coated peppers were increased but were still lower than in control samples. Atomic force microscopy images showed that the surface of sweet pepper without coating treatment was rougher than that of peppers treated with chitosan–oil coating. Our study suggests that chitosan–oil coating might be a promising candidate for enhancing the keeping quality of sweet peppers. 相似文献
103.
《Journal of Adhesion Science and Technology》2013,27(10-11):1591-1609
Abstract Atomic force miscroscopy (AFM) scratching at constant applied forces was used to quantify the adhesion of polymer coatings to cold rolled steel (CRS) and to study the effectiveness of a pretreatment for improving the adhesion. The pretreatment was a phosphate-free zirconia-based coating. Thin layers of commercially available epoxy, acrylic and polyester-based polymer coatings, were applied to polished or pretreated cold rolled steel substrates and the surface was scratched at the edge of the polymer coatings with the AFM tip at increasing values of normal loads until the coating was removed. Adhesion strengths were determined from the minimum tip-sample interaction force and number of cycles (scans) at a particular applied force. The pretreatment significantly improved adhesion of the epoxy and acrylic-based coatings on CRS. Adhesion of the acrylic-based coating was found to be better than the epoxy coatings on the bare as well as pretreated steel. Adhesive strength of the polyester-based coating was inconclusive because it was very easily removed on application of small forces using the AFM tip. The AFM scratching technique was found to provide a quick, easy and effective way to make quantifiable comparisons in relative adhesive strengths of polymer coatings and the effect of pretreatments. 相似文献
104.
以次亚磷酸钠为还原剂的塑料直接镀铜 总被引:6,自引:2,他引:4
以次亚磷酸钠为还原剂在ABS塑料表面进行化学镀铜,镀液的组成为:0.04mol/L的硫酸铜,0.28mol/L的次亚磷酸钠,0.051mol/L的柠檬酸钠,0.485mol/L的硼酸,以及5mg/L的2-2’联吡啶。化学镀5min后在该化学镀铜溶液中直接进行电镀铜。用原子力显微镜(AFM)、循环伏安法和X射线荧光光谱(XRF)分别研究了电镀层的形貌和次亚磷酸钠在该电镀液中的作用。15℃时,次亚磷酸钠在电镀液中不发生任何反应,镀层中只有Cu元素;50℃时,次亚磷酸钠发生电还原和歧化反应,镀层中不仅有Cu还有P,其中w(P)=6.56%:70℃时,次亚磷酸钠在溶液中仍有上述反应,只是还原峰向负方向发生了偏移,得到镀层中w(P)=14.36%:低温下可以获得较为致密、粗糙度小的镀层。因此,在电镀过程中,可以通过控制温度来调整铜镀层形貌及其磷元素含量。 相似文献
105.
High‐Strength and High‐Toughness Double‐Cross‐Linked Cellulose Hydrogels: A New Strategy Using Sequential Chemical and Physical Cross‐Linking
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Dan Zhao Junchao Huang Yi Zhong Kai Li Lina Zhang Jie Cai 《Advanced functional materials》2016,26(34):6279-6287
Polysaccharide‐based hydrogels have multiple advantages because of their inherent biocompatibility, biodegradability, and non‐toxicic properties. The feasibility of using polysaccharide‐based hydrogels could be improved if they could simultaneously fulfill the mechanical property and cell compatibility requirements for practical applications. Herein, the construction of double‐cross‐linked (DC) cellulose hydrogels is described using sequential chemical and physical cross‐linking, resulting in DC cellulose hydrogels that are mechanically superior to single‐cross‐linked cellulose hydrogels. The formation and spatial distribution of chemically cross‐linked domains and physically cross‐linked domains within the DC cellulose hydrogels are demonstrated. The molar ratio of epichlorohydrin to anhydroglucose units of cellulose and the concentration of the aqueous ethanol solution are two critical parameters for obtaining mechanically strong and tough DC cellulose hydrogels. The mechanical properties of the DC cellulose hydrogels under loading‐unloading cycles are described using compression and tension models. The possible toughening mechanism of double‐cross‐linking is discussed. 相似文献
106.
107.
退火工艺对钛酸锶钡薄膜结构的影响 总被引:4,自引:0,他引:4
采用射频磁控溅射在Pt/Ti/SiO2/Si(100)衬底上制备Ba0.6Sr0.4TiO3(BST)铁电薄膜,在500~750℃之间对薄膜快速退火。XRD分析表明:500℃时BST薄膜开始晶化为ABO3型钙钛矿结构,温度越高结晶越完整,晶粒越大。理论计算表明,薄膜在低温退火后无择优取向,高温退火后在(111)、(210)晶面有择优取向。退火气氛、保温时间、循环次数等因素对薄膜晶粒大小无明显影响,但对表面粗糙度和结晶程度影响较大。 相似文献
108.
109.
Inductively coupled plasma (ICP) processing has become the industrial processing standard for HgCdTe and its related II–VI
compounds. In this study ICP processes were developed that allow several microns of HgCdTe to be plasma etched while maintaining
a low root-mean-square (RMS) roughness, and even improving the surface roughness in the case of HgCdTe-on-Si. These ICP processes
are superior to older electron cyclotron resonance (ECR) plasma etches. The resulting ICP plasma processed surfaces are oxygen
and carbon free, have a good reflection high-energy electron diffraction (RHEED) pattern, and have only a small amount of
mercury depletion, x = 0.22 to 0.47 (where x is the ratio of Cd to␣Hg), in the first 25 ? to 30 ? of the HgCdTe. Nanofeatures of the as-grown HgCdTe are retained during
the process and are believed to be indicative of the fundamental defect mechanisms in the different HgCdTe etched surfaces.
Results from these experiments strongly suggest that ICP plasma processes can be used to delineate pixels, etch vias, clean
surfaces, and even produce epi-ready surfaces that would allow HgCdTe to become much more manufacturable, and perhaps allow
the replacement of wet processing in HgCdTe. 相似文献
110.