Ni-Mo电沉积层的组成和结构

利用Ｘ射线光电子谱（ＸＰＳ）研究了Ｎｉ－Ｍｏ沉积层的组成元素及其价态和深度分布,用扫描电子显微镜（ＳＥＭ）、Ｘ射线衍射技术（ＸＲＤ）和电子探针显微分析技术（ＥＰＭＡ）研究了电沉积Ｎｉ－Ｍｏ合金层的形貌、结晶状态、组成元素分布情况。结果表明,电沉积Ｎｉ－Ｍｏ合金层呈现亮色,表面比较均匀。电沉积层为非晶结构,２θ在４０°～５０°间有一弥散对称峰。沉积层中的Ｎｉ和Ｍｏ为零价态,它们的结合能分别为８５２．８ｅＶ和２２８．２ｅＶ。沉积层的真实组成（相对原子百分浓度）为：Ｎｉ５０．８６％,Ｍｏ２２．６３％,Ｏ２６．５１％。     

Development of a new high-shear and low-pressure grinding wheel and its grinding characteristics for Inconel718 alloy

Nickel-based alloy has been widely used due to its outstanding mechanical properties.However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting(SLM) manufactured Inconel718 all...     

颗粒增强金属基纳米复合材料脉冲电沉积制备研究

采用脉冲电沉积,在普通碳钢表面制备了Ni-W-P／CeO2-SiO2颗粒增强金属基纳米复合材料,研究了脉冲峰值电流密度和脉冲占空比对电沉积过程的影响,采用纳米颗粒的质量百分含量、沉积速率、显微硬度和表面形貌进行表征。结果表明：增加脉冲峰值电流密度或脉冲占空比,Ni—W—P基质金属晶粒细化,CeO2和SiO2纳米颗粒的质量百分含量提高。当脉冲频率为1000Hz,脉冲峰值电流密度和脉冲占空比分别为40A／dm^2和50％时,沉积速率最快（56．24μm／h）,显微硬度最高（712Hv）。此时,Ni—W—P基质金属轮廓清晰,晶粒细小而均匀,CeO2和SiO2纳米颗粒以弥散态均匀分散在基质金属中。     

Extension of continuous scanning laser Doppler vibrometry measurement for complex structures with curved surfaces

The continuous Scanning Laser Doppler Vibrometry (SLDV) developed on the base of the galvanometer scanner system has made it possible to quickly obtain the full field vibration responses within a rectangular area of the structure. In this paper, an arbitrary continuous scanning path generating method for Continuous Scanning Laser Doppler Vibometry (CSLDV) is further put forward in order to allow the CSLDV suitable for testing structures featured by complex shapes not just for regular areas. In the first step, the relationship between position of laser spot and the driving voltages of galvanometer scanner system has been described by a mathematical modeling. Then, a novel arbitrary scanning path generating strategy based on CSLDV is presented by deforming a normalization rectangular scanning path to an arbitrary continuous scanning path. The mapping relation between the normalization rectangular scanning path and arbitrary continuous scanning path is established using the reference points. In the second step, a compressor blade with curved surface was taken as an example for modal test using the proposed method. At the same time, a validated experiment was performed in SLDV. The results show the mode shapes derived from the extended CSLDV are in agreement with those from SLDV and the Modal Assurance Criterion (MAC) between the two are all greater than 0.96. They also demonstrate the feasibility and effectiveness of the proposed method for CSLDV test and show strong potential on further practical engineering applications.     

Encounter trajectories for deep space mission ASTER to the triple near Earth asteroid 2001-SN263. The laser altimeter (ALR) point of view

In cooperation with Russia, the Brazilian deep space mission ASTER plans to send a small spacecraft to investigate the triple asteroid 2001-SN263. The nearest launch opportunities for this project include June 2022 and June 2025. One main exploration campaign is being planned with focus on the largest asteroid (Alpha). Among the instruments under development, a laser altimeter (named ALR) was preliminarily designed and presented in 2010–2011. Many studies to define mission and instruments requirements were performed aiming at the characterization of important issues for the successful realization of the mission. Among them, the identification of a suitable trajectory that could be followed by the ASTER spacecraft in the encounter phase, when the main campaign will take place. This paper describes the effort undertaken with focus on the laser altimeter operation. Possible encounter trajectories were modelled and simulated to identify suitable approach parameters and conditions allowing the accomplishment of the intended investigation. The simulation also involves the instrument operation, considering approach geometry, attitude, relative motion, time/date, and the dynamics of the main asteroid. From the laser altimeter point of view, keeping in mind the desired coverage results (50% minimum surface coverage of asteroid Alpha, complying with horizontal and vertical resolution requirements), results point out crucial features for the encounter trajectory, like the need for a small inclination (10^-6 degrees; with respect to the asteroid's orbit), the most favourable spacecraft positioning (between the Sun and the asteroid) and pointing condition (back to the Sun), the minimum amount of achievable surface coverage (58%, focused on central areas), and the most proper time to conduct the main campaign (January 2025). Concerning the instrument, results offer refined values for divergence angle (500 to 650 μrad, half-cone), pulse repetition frequencies (from 1/20 to 1 Hz), and consequent data generation rates. A simulation tool that can use any 3D generated trajectories as input data was created for the analyses presented here. Although created for the ALR in this mission, this simple analysis tool can be adapted to other instruments in this or other missions.     

激光3D打印铁基块体非晶复合材料

Fe基非晶合金因强度高、硬度高、软磁性能优异等优势,得到人们极大关注。然而,目前实验室和工业领域利用铜模铸造法所能制备的Fe基非晶合金尺寸仍然较小,这严重制约了Fe基非晶合金作为结构材料在工业领域的实际应用。激光3D打印技术的出现为解决上述问题提供了难得的契机。然而,目前国内外的研究中,利用激光3D打印技术制备Fe基非晶合金存在较为严重的裂纹,所以无法利用该技术成型大尺寸的样品。在Fe基非晶合金中引入塑性较好的第二相来吸收热应力,防止在激光3D打印过程中发生开裂,能成功打印出大尺寸的Fe基非晶合金复合材料。通过上述方法成型的大尺寸Fe基非晶合金复合材料,宏观上没有裂纹发生且成型性良好,但微观上仍在局域发现微小裂纹。由于Cu将Fe基非晶合金包裹在中间,所以这些局域的微裂纹没有扩展,也没有贯穿整个材料,打印的Fe基非晶合金复合材料成型性没有受到较大影响。     

原子层沉积纳米钝化层薄膜厚度测量技术研究

原子层沉积无机纳米薄膜技术广泛应用于军民领域。本文通过在原子层沉积系统加装原位石英晶体微天平测量系统，通过原位石英晶体微天平研究原子层沉积无机薄膜生长过程并进行薄膜厚度的在线测量。通过研究原子层沉积反应条件，实现原子层沉积无机薄膜厚度的石英晶体微天平在线测量结果替代薄膜厚度线下光学测量结果，解决各类复杂腔体内壁原子层沉积薄膜厚度无法精确测量的问题。     

磁力研磨法去除燃油喷嘴积碳的试验研究

针对燃油喷嘴大修再制造中积碳难去除的问题。利用扫描电子显微镜（SEM）分析喷嘴表面积碳的微观形貌和成分组成，为磁力研磨技术去除积碳方法的确定和工艺研究奠定基础。从旋转磁场的产生原理、磁针在磁场中受力和磁针在磁场中运动三方面综合分析了磁力研磨法的材料去除机理。采用电磁研磨装置对喷嘴进行积碳去除试验，运用响应面分析法分析旋转磁场转速、磁针的型号尺寸和研磨时间的交互作用对材料去除量和表面粗糙度的影响规律，确定试验的最佳工艺参数。最优的工艺参数为：磁针型号尺寸Ø0.8 mm×5 mm，旋转磁场转速1 000 r/min，研磨时间40 min。通过微观形貌的观测以及表面应力检测分析，综合评价研磨后的喷嘴表面质量。结果表明，研磨后的喷嘴表面积碳基本去除，表面光滑，残余应力明显下降，金相组织完好。经过专业测试，研磨后的残余积碳小于技术要求规定值。采用磁力研磨技术，可以有效去除燃油喷嘴表面积碳，去除效率高，技术环保，满足绿色再制造的要求。     

Successes and challenges in non-destructive testing of aircraft composite structures

Composite materials are increasingly used in the aerospace industry. To fully realise the weight saving potential along with superior mechanical properties that composites offer in safety critical applications, reliable Non-Destructive Testing (NDT) methods are required to prevent catastrophic failures. This paper will review the state of the art in the field and point to highlight the success and challenges that different NDT methods are faced to evaluate the integrity of critical aerospace composites. The focus will be on advanced certificated NDT methods for damage detection and characterization in composite laminates for use in the aircraft primary and secondary structures.