采用特殊的钻头和底部钻具组合对井眼的保径至关重要

本文叙述了采用特殊的钻头和底部钻具组合对井眼的保径的重要性。指出如果采用特殊的钻头和扩孔器钻井,尽管投资较大,但所增加的投资可由增大钻速、减小扭矩和加大进尺等补偿回来。并通过钻头类型的选择;适用钻头的选择;特殊钻头的加工;底部钻具组合的说明进一步阐述各种保径齿钻头的特性及其效能。     

LASER CLADDED TiCN COATINGS ON THE SURFACE OF TTTANIUM

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs （OM）. The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm/s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm^-2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2 and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80μm, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

硅压力传感器的应力隔离封装

<正> 当封装压力传感器时,由于传感器芯片和管壳材料之间热膨胀系数的差别,在封接部位引入应力。这一封装应力引起传感器芯片硅膜     

磁流体静力分选机的发展现状

磁流体静力分选机用于分选高比重物料已有15年之久。首先试用于非磁性的废汽车碎片、预选贵金属以及金刚石的分选。分选比重可达12,000公斤/米~3。绐料粒度介于0.1～100毫米之间。在百分之百解离率条件下,完全分选是可能的。处理能力可达3.5吨/时,但其分选成绩取决于入选物料粒度和比重差。     

意大利圣·朱斯蒂纳坝实时洪水预报

介绍了用于意大利圣.朱斯蒂纳坝的实时洪水预报方法。根据10 a的小时库水位资料进行流量反演算,并重新构造了洪水系列。采用年最大流量与降雨深资料对简单的水文模型进行调整。考虑相应的洪水事件(11 a一遇洪峰流量),利用蒙特卡罗模拟法为洪峰流量预报制定了统计上可靠的方案。