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101.
102.
将MoS2粉末与铜粉、镍粉、铁粉、铅粉均匀混合后冷压并经880℃烧结,制备了Cu-10%MoS2和Cu-20%MoS22种销试样。以铬青铜QCr0.5为盘试样,采用自制的载流摩擦磨损试验机,研究了铜-二硫化钼粉末冶金材料的载流摩擦磨损性能。研究结果表明:在有电流条件下,加入MoS2可显著降低铜基粉末冶金/铬青铜配副的摩擦因数和铜基粉末冶金材料磨损率,10%和20%MoS2含量的粉末冶金试样的磨损率相差不显著,20%MoS2含量的摩擦因数在高速时有所增加。 相似文献
103.
以石墨/铜复合材料和QCr0.5铜合金为摩擦副,在自制的销盘摩擦磨损试验机上进行不同电流密度下的摩擦磨损试验,考察石墨含量对石墨/铜复合材料载流摩擦磨损性能的影响。结果表明:随着石墨含量的增加,石墨/铜复合材料的摩擦因数下降,载流效率和磨损率先下降后升高,石墨质量分数为10%时,载流效率最高,为12.5%时磨损率最低;随着电流密度的增加,石墨/铜复合材料的摩擦因数和载流效率下降,磨损率逐渐增加;石墨/铜复合材料在载流摩擦过程中存在黏着磨损、磨粒磨损和电弧烧蚀,电流密度较大时,电弧烧蚀比较严重。 相似文献
104.
105.
关于火工品延期机理和边界值的讨论 总被引:1,自引:0,他引:1
依据热爆炸理论,分析了火工品的延期机理,给出了延期火工品作用过程的燃速-时间、能量-时间物理模型。剖析了影响延期精度的诸因素,并推导出影响精度诸因素的时间值之和Δt(不稳态燃烧时间)与稳态燃烧时间t之比α(α=Δt/t)、Δt与延期技术指标中间值T之比β(β=Δt/T)分别存在边界值。 相似文献
106.
通过钢材碳当量与焊接性能相关性分析,探讨了溪洛渡水电站深孔不锈钢复合钢衬的可焊性.在实际焊接过程中,通过改变焊缝坡口型式和严格控制焊接工艺参数,解决了异种钢材之间焊接性能差的难题.研究结果表明,采用双V形坡口,调节焊接工艺参数,分别对钢衬基层、过渡层和复层焊接,焊后消缺处理,改善和保证了不锈钢复合钢衬的焊接质量. 相似文献
107.
On the friction and wear behavior of PTFE composite filled with rare earths treated carbon fibers under oil-lubricated condition 总被引:3,自引:0,他引:3
Carbon fibers (CF) were surface treated with air-oxidation, air-oxidation followed by rare earths (RE) treatment and RE treatment, respectively. The friction and wear properties of the polytetrafluoroethylene (PTFE) composites filled with differently surface treated carbon fibers, sliding against GCr15 steel under oil lubrication, were investigated on a reciprocating ball-on-disk UMT-2MT tribometer. The worn surfaces of the PTFE composites were examined using a scanning electron microscopy (SEM). Experimental results revealed that surface treatment of carbon fibers reduced the wear of CF-reinforced PTFE composites. Among all the treatments to carbon fibers, RE treatment was the most effective and lowest friction and wear rate of CF-reinforced PTFE composite was exhibited, owing to the effective improvement of the interfacial adhesion between the carbon fibers and PTFE matrix. 相似文献
108.
小流域治理中蓄水池工程设计探讨 总被引:1,自引:0,他引:1
蓄水池是较为常见的小型水利水保工程,在小流域治理中具有重要意义。针对江西省的水土流失特点,以国家水土保持重点建设工程江西省莲花县神路项目区神泉小流域为典型实例,根据“技术先进、经济合理、安全可靠”的原则,以《水土保持工程设计规范》(GB 51018-2014)为基础,从蓄水池工程布置、容量计算、组成与工程设计、安全稳定性计算等方面探讨了适宜江西省小流域治理中蓄水池工程的设计标准,对江西省以及南方红壤区的水土流失防治与水土保持规划设计具有一定的技术指导意义。 相似文献
109.
Hong Shangguan Yi Liu Xueying Cui Yunjiao Bai Quan Zhang Zhiguo Gui 《International journal of imaging systems and technology》2016,26(1):3-14
It is a significant challenge to accurately reconstruct medical computed tomography (CT) images with important details and features. Reconstructed images always suffer from noise and artifact pollution because the acquired projection data may be insufficient or undersampled. In reality, some “isolated noise points” (similar to impulse noise) always exist in low‐dose CT projection measurements. Statistical iterative reconstruction (SIR) methods have shown greater potential to significantly reduce quantum noise but still maintain the image quality of reconstructions than the conventional filtered back‐projection (FBP) reconstruction algorithm. Although the typical total variation‐based SIR algorithms can obtain reconstructed images of relatively good quality, noticeable patchy artifacts are still unavoidable. To address such problems as impulse‐noise pollution and patchy‐artifact pollution, this work, for the first time, proposes a joint regularization constrained SIR algorithm for sparse‐view CT image reconstruction, named “SIR‐JR” for simplicity. The new joint regularization consists of two components: total generalized variation, which could process images with many directional features and yield high‐order smoothness, and the neighborhood median prior, which is a powerful filtering tool for impulse noise. Subsequently, a new alternating iterative algorithm is utilized to solve the objective function. Experiments on different head phantoms show that the obtained reconstruction images are of superior quality and that the presented method is feasible and effective. 相似文献
110.
Shihong Xu Wenfeng Shangguan Jian Yuan Mingxia Chen Jianwei Shi 《Applied catalysis. B, Environmental》2007,71(3-4):177-184
A magnetically separable nitrogen-doped photocatalyst TiO2−xNx/SiO2/NiFe2O4 (TSN) with a typical ferromagnetic hysteresis was prepared by a simple process: the magnetic SiO2/NiFe2O4 (SN) dispersion prepared by a liquid catalytic phase transformation method and the visible-light-active photocatalyst TiO2−xNx were mixed, sonificated, dried, and calcined at 400 °C. The prepared photocatalyst is photoactive under visible light irradiation and easy to be separated from a slurry-type photoreactor under the application of an external magnetic field, being one of promising photocatalysts for wastewater treatment. Transmission electron microscope (TEM) and X-ray diffractometer (XRD) were used to characterize the structure of the TSN photocatalyst. The results indicate that the magnetic SiO2/NiFe2O4 (SN) nanoparticles adhere to the surface of TiO2−xNx congeries. The magnetic photocatalyst TSN shows high catalytic activity for the degradation of methyl orange in water under UV and visible light irradiation (λ > 400 nm). SiO2 coating round the surface of NiFe2O4 nanoparticles prevents effectively the injection of charges from TiO2 particles to NiFe2O4, which gives rise to the increase in photocatalytic activity. Moreover, the recycled TSN exhibits a good repeatability of the photocatalytic activity. 相似文献