离子镀Ti(N,C)耐磨镀层成分与性能研究

 用空心阴极离子镀技术,在常用的不锈钢(1Cr18Ni9Ti)基材上,镀制Ti(N,C)耐磨镀层。对镀层的成分进行了分析,讨论了镀层成分的耐磨性,显微硬度和附着力的影响。通过对Ti(N,C)镀层与TiN和TiC镀层性能的对比,肯定了Ti(N,C)复合化合物镀层具有更优越的耐磨性和附着力。     

汽心泵特性研究

 通过理论分析和试验,导出汽心泵稳定工作的基本方程和性能参数之间的函数关系;分析了当转速、压力、流量和负载系数变化时,汽心对泵特性所起的调节作用;提出决定相对汽心直径的特征参数p_2/n~2D_2~2;还讨论了汽心泵的极限工作状态和最大流量调节范围。     

电子束物理气相沉积LaZrCeO热障涂层微结构与热循环性能

热障涂层(thermal barrier coatings,TBCs)是一种由金属黏结层、热生长氧化物层和陶瓷面层组成的金属-陶瓷复合系统,在先进的航空发动机领域上引起了广泛的关注,但目前先进热障涂层的热循环寿命提升和失效行为研究仍然是一个难点。本研究采用电子束物理气相沉积技术(electron beam physical vapour deposition,EB-PVD)制备LaZrCeO/YSZ双陶瓷层热障涂层,研究热障涂层的相结构、显微组织和失效行为。结果表明:LaZrCeO/YSZ涂层为烧绿石与萤石结构组成的复合涂层材料,LaZrCeO/YSZ涂层的微观结构由羽毛状纳米结构和柱内孔隙组成;在1100℃热循环条件下,LaZrCeO/YSZ双陶瓷层热障涂层展现了良好的热循环寿命;热循环实验后,由于应力累积的作用裂纹在热生长氧化层(TGO)中萌生并扩展,包括水平裂纹和垂直裂纹两大类,进而引起整个涂层体系的不稳定,最终导致涂层失效。     

化学气相沉积/渗透技术综述

综述了化学气相沉积技术的最新发展，包括金属有机化合物化学气相沉积，等离子辅助化学气相沉积，激光化学气相沉积；同时介绍了三种用于制备工程材料的快速致密化化学气相渗透技术，包括强迫流动热梯度化学气相渗透，化学液相沉积，感应加热热梯度快速致密化技术。     

Comparison of satellite orbit ephemerides for use in GPS meteorology

This paper discusses GPS (Global Position System) meteorology. The research presented is based on a comparison of values of precipitable water vapour PWV, based on GPS measurements using final and predicted ephemerides of satellite orbits. We analysed recent year’s improvement in predicting ephemerides. We compared the data outputs from a radiosonde using GPS receiver measurements directly from the meteorological station from which the radiosondes were launched. The results indicate a high quality of the predicted ephemerides. This finding makes predicted ephemerides highly usable for near real-time estimations of PWV. To use PWV in meteorological forecast applications, this high speed of PWV values supply is necessary.     

Analysis of precipitable water vapour characteristics from GNSS measurements during the snow season in Liaoning Province,China

Global Navigation Satellite System (GNSS) remote sensing precipitable water vapour (PWV) data from November 2015 to March 2019 were combined with snowfall observation data and used to analyse PWV characteristics in Liaoning Province during the snow season (from November to March the following year) and their relationship with snowfall. The potential of using GNSS for PWV measurements was demonstrated using sounding data with a correlation coefficient higher than 0.9 and a mean bias error lower than 0.5 mm. According to the GNSS PWV data gathered at 30-min intervals from 68 GNSS stations in Liaoning during the snow season, the monthly PWV average was highest in November and lowest in January. Negative correlations were found between PWV and altitude. Most of the water vapour was concentrated in the low layer of the atmosphere, and the contribution of this vapour to the PWV was higher during the snow season than in summer. A total of 43 snow cases were identified using the snowfall records from 53 GNSS stations, and the characteristics of PWV during these snowfalls were analysed. An increase in PWV was observed before snowfall events. Moreover, the influence of synoptic systems and air mass origins on PWV was analysed based on National Centers for Environmental Prediction (NCEP) reanalysis data and the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results show that the water vapour condition was better when the synoptic systems or air masses came from areas south of Liaoning.     

GNSS water vapour tomography – Expected improvements by combining GPS,GLONASS and Galileo observations

The German Research Centre for Geosciences (GFZ) operates a GNSS water vapour tomography system using about 350 German GNSS stations. The GNSS data processing at the GFZ works in near real-time and provides zenith total delays, integrated water vapour and slant delay data operationally. This large data set of more than 50,000 slant delays per hour is used to reconstruct spatially resolved humidity fields by means of tomographic techniques. It can be expected that additional observations from the future Galileo system provide more information with improved quality. A simulation study covering 12 h at 14 July 2009 was therefore started to estimate the impact of GPS, Galileo and GLONASS data on the GNSS tomography. It is shown that the spatial coverage of the atmosphere with slant paths is highly improved by combining observations from two or three satellite systems. Equally important for a reliable tomographic reconstruction is the distribution of slant path intersections as they are required to locate the integrated delay information. The number of intersection points can be increased by a factor of 4 or 8 if two or three systems are combined and their distribution will cover larger regions of the atmosphere. The combined data sets can be used to increase the spatiotemporal resolution of the reconstructed humidity fields up to 30 km horizontally, 300 m vertically and 15 min. The reconstruction quality could not be improved considerably using the currently available techniques.     

大尺寸金刚石膜生长中等离子体弧源的稳定性

保持等离子体弧源稳定性对于制备大尺寸平面金刚石膜极其重要,故从理论和实验两个方面对等离子体弧源稳定性进行了分析。研究表明,为了保持弧源的稳定,必须在生长过程中,保持稳定的电子温度和均匀的活性原子及原子基团密度。金刚石膜在某些条件下长时间生长时,会发生阳极环积碳现象,导致等离子体弧源扰动失稳,从而引起生长的金刚石膜含有石墨杂质。通过预处理阳极环、控制碳源、加大氢气量等措施可保持弧源稳定。在此条件下生长金刚石膜,经SEM,Raman分析表明,其晶粒均匀、晶界清晰,仅有金刚石特征峰出现。     

Development of a micro-balance system for dust and water vapour detection in the Mars atmosphere

Quartz crystal piezoelectric sensors are suitable for deposition analyses that need very high sensitivity. Due to the wide working ranges and high performances, micro-balances can measure the mass settling in average Mars conditions during a period of months before saturation is reached. This ensures a proper use for short and long term water and dust deposition monitoring. Micro-balances have been studied, calibrated and used for the GIADA (grain impact analyser and dust accumulator) experiment for the ESA-Rosetta space mission. Experience on micro-balance performance study by dust deposition has been acquired and water vapour deposition studies are in progress in a Martian atmosphere simulation chamber. Preliminary results show that micro-balances are capable to detect up to partial pressure values corresponding to parts per billion of the typical Martian atmosphere.     

CVD金刚石薄膜表面抛光技术的研究

对CVD金刚石膜的离子束铣削、电子束加工、激光加工、化学辅助机械抛光、热化学抛光等抛光技术的加工方法与原理进行了介绍,分析了这些方法的优点和不足之处。并展望了CVD金刚石薄膜抛光技术的发展方向。