Initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments

The initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments（pH = 3.5） are studied by Scanning Electron Microscope（SEM）, optical microscope, Fourier Transform Infrared Spectroscopy（FT-IR）, X-Ray Diffraction（XRD）, potentiodynamic polarization, Electrochemical Impedance Spectroscopy（EIS）, and Scanning Kelvin Probe（SKP）. The results show that pitting corrosion occurs at the initial corrosion stage, and the potential difference between the seco...     

航天器电子产品加速试验技术现状及探讨

随着电子产品在航天器中占比越来越高,采用加速试验来进行航天器电子产品的可靠性验证与评估成为一种高效的手段。文章综述了加速试验技术在航天器各层次电子产品中的应用现状,并且根据航天器研制特点梳理了航天器电子产品加速试验类型及加速试验设计方法,给出了我国在该领域开展研究工作的建议。     

电子产品振动应力筛选试验方法应用探讨

正确的振动应力筛选试验方法在电子产品研制工程中扮演着重要的角色。文章从GJB 1032给出的筛选的目的和对象着手分析,讨论振动应力筛选的条件和方法;就工程中常见的几种"欠筛选"和"过筛选"情况进行深入探讨,分析研究了几种正确的振动应力筛选方法。根据产品实际情况选择正确的筛选条件,并采用相应的带谷控制方法,能够避免欠筛选和过筛选,完成规定的筛选任务。     

论文化产品品牌培育策略

国家“十二五”规划提出将文化产业发展成国家的支柱性产业,而文化产品是文化产业的终端,文化产品品牌的培育则能促进文化产品的发展.文章分析了文化产品品牌培育的必要性以及文化产品品牌的内涵,认为政府的政策制度、居民可支配收入以及文化产品的创新性是影响当前文化产品品牌培育的因素.基于此得出文化产品品牌培育的对策：政府制定政策法规对文化产品品牌进行扶植,培育文化产品消费群体以及推进文化产品内容创新.     

飞机结构腐蚀疲劳寿命预估工程方法研究

简要地说明了飞机结构在腐蚀环境中的破坏模式、腐蚀破坏的分析预估方法和结构服役日历年限预估方法。通过算例说明了分析过程。     

Effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings

The present work examines the effects of cerium salts on corrosion behaviors of Si–Zr hybrid sol–gel coatings. The Si–Zr hybrid sol–gel coatings on a 2A12 aluminum substrate were prepared through hydrolysis and condensation of glycidoxypropyl-trimethoxy-silane(GTMS) and zirconium(IV) n-propoxide(TPOZ). Used as inhibitors for corrosion, three types of cerium salts(Ce(NO_3)_3, CeCl_3, and Ce(CH_3COO)_3) were doped into the sol–gel coatings. Fourier transform infrared(FTIR) and scanning electron microscopy(SEM) were employed to investigate the structures and morphologies of various coatings, and the corrosion resistances of the coatings were evaluated by electrochemical methods and neutral salt spray tests. Experimental results indicate that the addition of cerium salts can hinder the process of corrosion due to their self-healing abilities. Furthermore, the sol–gel coating doped with Ce(CH_3COO)_3 has the best corrosion resistance because of the promotions of hydrolysis and condensation provided by CH_3COO.     

Wobble of a spin stabilized satellite with cross products of inertia and magnetic attitude control

Asymmetrical spin stabilized satellite dynamics in the vicinity of the required motion is considered. The principal axis of the maximum moment of inertia slightly deviates from its assumed direction in the satellite reference frame. This is formalized in the cross products of inertia. This inertial uncertainty results in a wobble, that is undesired angular velocity components perpendicular to the rotation axis, and oscillations of this axis near the required direction. The torque-free motion is investigated first. Expressions that explicitly relate satellite inertia parameters to wobble are provided. Wobble evolution under the action of magnetic damping control is analyzed next. Its amplitude approximate exponential decay behavior and residual unavoidable wobble level are derived. These expressions are compared with numerical simulation results of nonlinear equations of motion including various disturbance sources.     

Photo-alteration of hydantoins against UV light and its relevance to prebiotic chemistry

Aqueous solutions of 5-substituted hydantoins were irradiated with ultraviolet (UV) light, to investigate their structural stability against UV radiation as well as the possible photolysis products. The photolysis products were identified and the degree of photolysis was measured using reversed-phase and ion-exchange high-performance liquid chromatography. Hydantoin (2,4-imidazolidinedione) was dominantly detected as a photolysis product of 5-substituted hydantoins. With hydrolysis of UV-irradiated 5-substituted hydantoins, glycine and alanine were dominantly detected. These experimental results are important for the prebiotic photochemistry of 5-substituted hydantoins in the formation of hydantoin since they have been detected in Solar System materials.     

航空电子产品印制电路板组件中性清洗技术研究

印制电路板清洗是电子装配中的一个重要环节,它对电子产品的质量和可靠性有着极为重要的作用。通过对印制板清洗原理与影响因素分析,针对性使用优化参数的中性水基清洗剂对印制板组件进行试验,证实该类型清洗剂能够满足航空电子产品在印制板清洗方面的需求。     

模拟过载条件下燃烧室凝相颗粒形态参数试验研究

通过地面模拟过载粒子收集试验装置,完成了推进剂在3种不同压强工况下的粒子收集试验,初步获得了粒度分布特性、微观形貌特性及成分分布等形态参数。研究结果表明,粒子中径分布明显高于非过载状态,5.6~11.5 MPa范围内,d(0.5)主要分布在120~190μm之间。同时,针对某飞行试验发动机残骸故障处残留凝相粒子进行了收集与分析,并与地面同种压强状态下粒子形态参数进行了对比,两者分布较为一致,均呈双峰分布,粒子d(0.5)约为100~130μm。