热激励谐振式硅微结构压力传感器温度场研究

针对一种以方形硅膜片为一次敏感元件、硅梁谐振子为二次敏感元件 ;采用电阻热激励、压敏电阻拾振的压力微传感器 ,分析了其工作机理 ;依幅值、相位条件讨论了该谐振式微传感器的闭环自激系统 ;建立了微传感器的温度场模型和热应力模型 ,并进行了仿真计算与分析     

大型薄壁铸件铆接裂纹原因分析

某飞机上的一大型薄壁铸件在与蒙皮铆接时多次发生开裂,造成严重的安全隐患.通过对故障件进行的断口宏、微观检查,金相组织分析以及相关工艺试验,经综合分析讨论,明确了铸件铆接时出现裂纹的原因.结果表明:该零件铸造时变质处理不充分,材质塑性差,降低铆接时承受冲击的能力是导致开裂的主要原因,零件装配存在应力也是导致开裂的重要因素.     

利用电化学方法制备有序多孔硅阵列

采用电化学刻蚀的方法，在自制的电解槽中制备n型〈100〉晶向多孔硅条状阵列。通过扫描电子显微镜对生成的多孔硅进行形貌观察，并对多孔硅条状阵列的生长速率与形貌进行了初步的理论分析和实验研究。实验结果表明，多孔硅的生长速率主要由临界电流密度决定，多孔硅生成初始阶段产生锥形刻痕的原因是初始电流密度比较小，加大电流密度可以消除刻痕。多孔硅分又是由孔间距远远大于自由电荷区而产生的，而深槽中出现分立小孔的原因是反应产生的氢气阻碍了阳极氧化的进行。本实验结果对开展多孔硅进一步的研究工作具有指导意义。     

碳纤维表面CVD硅涂层对其性能的影响

 分析了碳纤维表面化学气相沉积Ｓｉ涂层的相结构,研究了Ｓｉ涂层对碳纤维抗氧化性能及强度的影响。结果表明：涂层中Ｓｉ元素呈非晶态分布；Ｓｉ涂层可提高碳纤维的抗氧化性能；氧化温度不同,Ｓｉ涂层碳纤维的氧化失重或增重规律也不相同。同时,Ｓｉ涂层降低了碳纤维拉伸强度,而适度空气氧化又可使Ｓｉ涂层碳纤维强度得到大幅度提高；Ｓｉ涂层碳纤维的强度随氧化温度、氧化时间的变化而改变。     

Advanced Technologies Demonstrated by the Miniature Integrated Camera and Spectrometer (MICAS) Aboard Deep Space 1

MICAS is an integrated multi-channel instrument that includes an ultraviolet imaging spectrometer (80–185 nm), two high-resolution visible imagers (10–20 μrad/pixel, 400–900 nm), and a short-wavelength infrared imaging spectrometer (1250–2600 nm). The wavelength ranges were chosen to maximize the science data that could be collected using existing semiconductor technologies and avoiding the need for multi-octave spectrometers. It was flown on DS1 to validate technologies derived from the development of PICS (Planetary Imaging Camera Spectrometer). These technologies provided a novel systems approach enabling the miniaturization and integration of four instruments into one entity, spanning a wavelength range from the UV to IR, and from ambient to cryogenic temperatures with optical performance at a fraction of a wavelength. The specific technologies incorporated were: a built-in fly-by sequence; lightweight and ultra-stable, monolithic silicon-carbide construction, which enabled room-temperature alignment for cryogenic (85–140 K) performance, and provided superb optical performance and immunity to thermal distortion; diffraction-limited, shared optics operating from 80 to 2600 nm; advanced detector technologies for the UV, visible and short-wavelength IR; high-performance thermal radiators coupled directly to the short-wave infrared (SWIR) detector optical bench, providing an instrument with a mass less than 10 kg, instrument power less than 10 W, and total instrument cost of less than ten million dollars. The design allows the wavelength range to be extended by at least an octave at the short wavelength end and to ∼50 microns at the long wavelength end. Testing of the completed instrument demonstrated excellent optical performance down to 77 K, which would enable a greatly reduced background for longer wavelength detectors. During the Deep Space 1 Mission, MICAS successfully collected images and spectra for asteroid 9969 Braille, Mars, and comet 19/P Borrelly. The Borrelly encounter was a scientific hallmark providing the first clear, high resolution images and excellent, short-wavelength infrared spectra of the surface of an active comet’s nucleus.     

先驱体转化法制备致密SiC／Si3N4复相陶瓷异形件—烧结工艺研究

研究了以陶瓷先驱体为粘合剂成型并转化制备致密ＳｉＣ／Ｓｉ３Ｎ４复相陶瓷异形件的烧结工艺及其对烧结体的结构和性能的影响。     

X射线数字成像系统传递函数模型

基于非晶硅面阵探测器的工业X射线数字成像系统是目前最先进的射线检测技术,其系统传递函数PSF(Point Spread-Function)由非点源形成的系统几何弥散、闪烁体膜层弥散、探测器像元孔径采样3部分组成.通过分析各环节射线透照场强的分布特性,以高斯函数近似各环节相应PSF的数学表达式,建立了整个数字成像系统的PSF及其MTF(Modulation Transfer Function)理论模型,并由系统PSF的半波宽得到系统的近似有效带宽.以PaxScan2520面阵探测器组成的X射线数字成像系统为例,通过实验验证了该模型的合理性,利用此模型可快速估计数字成像系统可分辨被检试件的最小细节,为工业射线检测提供理论基础.     

碳化物和硼化物陶瓷强韧化

从相复合、晶粒细化、裂纹改向和相变韧化角度论述了有关碳化物和硼化物的强韧化问题。     

大尺寸轻型SiC光学反射镜研究进展

本文比较了光学玻璃、硅、铍，碳化硅等太空反向镜片材料的物理性能和机械性能，着重介绍了新型光学反向镜片材料碳化硅的种类、制造和应用，并讨论了碳化硅作为太空反向镜片材料目前存在的问题及发展方向。     

聚碳硅烷/纳米钛粉的热裂解

运用ＩＲ、ＸＲＤ和ＴＧ等分析手段研究了掺混纳米钛粉的聚碳硅烷的热裂解过程。发现热解过程可分为有机硅聚合物转化为无机无定形态和无定形态生长为微晶成。裂解产物中钛的存在形态随保护气氛不同而不同,保护气氛为氮气或氨气时钛的裂解产物为ＴｉＮ,氩气时为ＴｉＣ。