激光沉积制备Nb3Al基难熔金属间化合物研究

通过控制激光功率使Nb-12Ti-22Al(at%)和Nb-22Al(at%)两种成分配比的混合元素粉末在Ti-6Al-4V基体上激光沉积合成了Nb3Al基难熔金属间化合物,并达到了预期设定的成分配比,其显微组织均匀细小,在δ-Nb3Al基体上分布着不同形态的β-Nbss.在合适的激光功率下,无裂纹的沉积层厚度有一定的限制,随着沉积厚度的增加,沉积层中残余拉应力增大,沉积薄壁件容易在底部发生断裂.由于Ti的添加使Nb-12Ti-22Al的的裂纹倾向性小于Nb-22Al.     

HFCVD系统热丝参数遗传优化

在热丝化学气相沉积金刚石系统中，衬底温度是影响金刚石成膜质量的关键因素之一。为了沉积大面积优质金刚石膜，必须对衬底表面温度的大小及均匀性实施有效控制。中通过应用遗传算法对热丝参数进行优化设计，保证了衬底在半径为Rs＝10cm的范围内具有较均匀的温度场，从而为大面积生长优质金刚石膜提供了可能。     

Potentials of manufacture and repair of nickel base turbine components used in aero engines and power plants by laser metal deposition and laser drilling

IntroductionExpensive turbine parts like HPT(HighPressure Turine)blades or vanes are replaced bynew parts in case of damage.For example theburn through of the inner side of a blade or vane(Figure 1)is a frequently appearing damage,which cannot be repaired…     

Influence of welding parameters on microstructure and mechanical properties of electron beam welded Ti60 to GH3128 joint with a Cu interlayer

Effects of welding parameters on the microstructure and mechanical properties of Ti/Cu/Ni joint welded by electron beam were investigated. High welding heat input increased the melting quantity of Ti60 titanium alloy and promoted the formation of Ti–Cu intermetallic compounds (IMC) such as Ti₂Cu and Ti₃Cu₄, increasing the brittleness of the joints. Low welding heat input was not conducive to the complete melting of the copper interlayer, and the unmelted copper reduced the performance of the joints. Under the optimal welding parameters, Ti–Ni IMCs in the weld would be replaced by (Cu, Ni) solid solutions ((Cu, Ni)_ss). However, Ti–Cu IMC layers cannot be eliminated entirely by changing the welding parameters. The maximum tensile strength of the joints was 201 MPa. The fracture of the joints occurred at the Ti–Cu IMC layer, which was a typical brittle fracture.     

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。     

Statistical study of energetic electrons in Jupiter’s inner magnetosphere by Juno/JEDI

The Juno spacecraft made the first in-situ observations of energetic particles in the polar region of Jupiter’s magnetosphere. After Jupiter Orbit Insertion (JOI) in July 2016, data from ~20 Juno perijoves (PJs) obtained by Juno/JEDI are accumulated, providing an excellent opportunity to study the long term spatio-temporal distribution of energetic particles in Jupiter’s radiation belt. We transform Juno’s position from a Cartesian to a magnetic coordinate system by tracing magnetic field lines based on a fourth order Runge-Kutta method. Then the fluxes of energetic electrons from PJ1 to PJ14 sorted by different locations in magnetic coordinate space and the data are well organized by the L-shell parameter. The variation of electron flux increases with L-shell. The deviation (the ratio of the 75th percentile to the 25th percentile) of 0.51 MeV electron flux varies from a factor of 1.23 near L = 9.5 to 27.57 near L = 15.5. However, the mean flux decreases by about one order of magnitude in the same region. The electron spectra at larger L-shells are softer than that at smaller L-shells. On the other hand, the electron flux decreases more rapidly with increased L-shell when the location is off the equator. Along an L-shell, the electron flux decrease at first and then increase again from equator to mid-latitude region. In addition, we compare the statistical results with the widely used GIRE2 model. JEDI data correspond well with the GIRE2 model when the L-shell is > 14.75. GIRE2 underestimate the electron flux for L-shell smaller than 13.25. These results of this analysis are applicable to estimate the effects of the radiation environment in Jupiter’s magnetosphere.     

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。     

Detection of the ionospheric disturbances on GPS-TEC using Differential Rate Of TEC (DROT) algorithm

The solar, geomagnetic, gravitational and seismic activities can cause spatial and temporal (hourly, diurnal, seasonal and annual) variabilities of the ionosphere. Main observable ionospheric parameters such as Total Electron Content (TEC) can be used to quantify these. TEC is the total number of electrons on a ray path crossing the atmosphere. The network of world-wide Global Positioning System (GPS) receivers provide a cost-effective solution in estimating TEC over a significant proportion of global land mass. This study is focused on the analysis of the variations of ionosphere over a midlatitude region using GPS-TEC estimates for three Sun Spot Numbers (SSN) periods. The investigation is based on a fast and automatic variability detection algorithm, Differential Rate Of TEC (DROT). The algorithm is tested using literature data on disturbances generated by a geomagnetic activity, a Solar Flare, a Medium Scale Travelling Ionospheric Disturbance (MSTID), a Large Scale TID (LSTID) and an earthquake. Very good agreement with the results in the literature is found. DROT is applied to IONOLAB-TEC estimates from nine Turkish National Permanent GPS Network (TNPGN Active) stations over Turkey to detect the any wave-like oscillations, sudden disturbances and other irregularities during December, March, June, September months for 2010, 2011, 2012 years. It is observed that DROT algorithm is capable of detecting both small and large scale variability due to climatic, gravitational, geomagnetic and solar activities in all layers of ionosphere. The highest DROT values are observed in 2010 during winter months. In higher solar activity years of 2011 and 2012, DROT is able to indicate both seasonal variability and severe changes in ionosphere due to increased number of geomagnetic storms and local seismic activities.     

10 cm ECR中和器性能优化实验研究

针对电子回旋共振(ECR)中和器性能无法满足实际应用需求的问题，开展了10 cm ECR中和器的性能优化实验研究，在分析现有ECR中和器内部结构的基础上，提出新的结构改进方案。通过改进ECR中和器的电子束流引出对比实验，得到了中和器结构对束流引出性能的影响规律。优化后的ECR中和器性能实验表明：相同条件下ECR中和器束流引出大小与气体流量大小不成正相关，但随着微波功率的增加而增加。性能实验得到的中和器最佳工作和性能参数为：微波功率为10 W、氙气流量为0.5 sccm，收集板间距为5 mm时，在50 V引出电压条件下能够引出127 mA的电子束流。     

SAMI2 model results for the quiet time low latitude ionosphere over India

Efficacy of SAMI2 model for the Indian low latitude region around 75°E longitudes has been tested for different levels of solar flux. With a slight modification of the plasma drift velocity the SAMI2 model has been successful in reproducing quiet time ionospheric low latitude features like Equatorial Ionization Anomaly. We have also showed the formation of electron hole in the topside equatorial ionosphere in the Indian sector. Simulation results show the formation of electron hole in the altitude range 800–2500?km over the magnetic equator. Indian zone results reveal marked differences with regard to the time of occurrence, seasonal appearances and strength of the electron hole vis-a-vis those reported for the American equatorial region.