退火工艺对H62黄铜显微组织与力学性能的影响

采用不同的加热温度和冷却方法对H62黄铜进行退火工艺试验,对退火处理后H62黄铜的显微组织、硬度及抗拉强度进行了分析。结果表明:在600~750℃退火温度范围内,H62黄铜出炉后直接空冷得到的显微组织均为α+β相,且随着退火加热温度的升高,显微组织中的β相逐渐增多,材料的硬度和抗拉强度逐渐升高,且抗拉强度均高于技术要求;H62黄铜经650℃退火保温后先随炉缓冷至500℃再出炉空冷,可得到单一均匀的α相组织,材料的硬度和抗拉强度均最低,且抗拉强度满足技术要求。     

铝合金异形波导管的热挤压

论述了Ｐ４Ａ１４８３－４型铝合金异形波导管的挤压模设计和挤压工艺选择；提出了采用分流组合模挤压工艺制造复杂形状的异形波导管。     

H68黄铜弹壳开裂原因分析

通过化学成分分析、裂纹宏观和微观检验、显微硬度测试与微区成分能谱分析等方法,分析了H68黄铜弹壳开裂失效的原因。结果表明：材料本身存在冶金缺陷β相偏析与零件收口处退火不良是造成弹壳开裂失效的原因。     

液化石油气输送用黄铜管开裂原因分析

H62黄铜管用作液化石油气输送管使用不久后,在靠近烧嘴附近产生了开裂.采用等离子光谱、金相、扫描电镜和能谱等方法对黄铜管开裂原因进行了分析.结果表明,黄铜管发生了明显的脱锌现象,基体强度明显降低.黄铜管中有害杂质元素铅含量略微偏高,且分布在晶界,容易引起黄铜管的热脆性.在内应力存在的条件下,黄铜管发生破裂.最后提出了相应的改进的建议.     

铜合金垫片表面类金刚石薄膜的制备及其摩擦学性能研究

采用物理气相沉积工艺在黄铜H62垫片上制备了DLC薄膜,对DLC薄膜进行了拉曼光谱分析和截面形貌观察,测试了薄膜厚度、纳米硬度和结合力,进行了磨擦磨损试验,分析了薄膜的减摩耐磨性能.结果 表明,在H62铜合金垫片制备碳膜为DLC薄膜,薄膜总厚约2.31 μm,底层厚约0.49 μm.薄膜纳米硬度22.1GPa,薄膜与基...     

盘荷波导结构高频特性分析及其在高功率速调管中的应用

以周期边界法、谐振法以及微扰法分别对盘荷波导结构色散特性、耦合阻抗进行分析,研究了不同结构参数下盘荷波导结构高频特性的变化规律.设计了C波段π/2模速调管盘荷波导输出结构,对其注-波互作用开展了PIC粒子模拟.计算结果表明,相对于传统单间隙圆柱输出腔,盘荷波导输出结构可以在获得高效率的同时显著降低输出间隙场强.     

离子注入在1.3μm面发射激光器结构中的应用

研究了H 离子注入对InP材料和1.3μm面发射激光器结构的电学、光学性能的影响.当离子注入后InP表面电学特性退化,在300℃以上退火后,材料表面回复较好,H 离子注入区电阻率约为InP体材料的104倍.接着,将离子注入工艺应用于1.3μm面发射激光器结构电流限制孔径的制作,通过比较电学特性得出450℃的最佳退火温度,并发现高温退火后电致发光强度增强.     

滚齿加工精度和效率的研究分析

滚齿是一种常用的齿轮加工工艺,在高精度滚齿机上,采用精密滚刀,可以加工出5到6级精度的齿轮。本文结合多年对齿轮制造理论的研究,对保证滚齿精度的前提下,对提高齿轮滚齿加工效率的方法及途径进行了研究分析。     

高精度矩形弯铜波导管加工研究

高精度矩形弯铜波导管一直采用制造周期长的电铸加工而成,为了寻求快速的制造方法,进行了系列的模具压制成形实验,改变了凸模结构,改进了成形工艺,快速地制造出合格的产品。     

新型低损耗级联式1×4光分路器的优化设计

为改进传统Y分支光分路器损耗较大的缺陷,我们采用激模波导结构设计新型Y分支波导和由三个分支级联的新型Y分支波导构成低损耗1×4光分路器.设计中利用辐射模和本征基模的叠加来修正光波场,通过改善模匹配来降低分支耦合损耗,同时在1×4光分路器中加入直波导来改善和优化分路器的输出均匀性,并用有限差分光束传播法对该Y分支波导和1×4光分路器进行数值模拟.模拟结果表明,该结构具有均匀性好、损耗小和结构简单等优点,有利于器件的进一步集成和大批量生产.     

The defect mode in a low-dimensional waveguide microwave photonic crystal

It is shown that the violation of periodicity in a low-dimensional waveguide microwave photonic crystal, in which the periodic structure is formed by dielectric layers and adjacent metal plates partly overlapping the waveguide cross section and forming capacitive gaps between the plate edge and wide wall of the waveguide, leads to the appearance of a defect (impurity) mode. It is established that the defect mode position on the frequency scale significantly depends on both the thickness of “disturbed” dielectric layer and the capacitive gap width of diaphragms.

     

Dynamics and stability of flow down a flexible incline

The flow of a thin liquid film down a flexible inclined wall is examined. Two configurations are studied: constant flux (CF) and constant volume (CV). The former configuration involves constant feeding of the film from an infinite reservoir of liquid. The latter involves the spreading of a drop of constant volume down the wall. Lubrication theory is used to derive a pair of coupled two-dimensional nonlinear evolution equations for the film thickness and wall deflection. The contact-line singularity is relieved by assuming that the underlying wall is pre-wetted with a precursor layer of uniform thickness. Solution of the one-dimensional evolution equations demonstrates the existence of travelling-wave solutions in the CF case and self-similar solutions in the CV case. The effect of varying the wall tension and damping coefficient on the structure of these solutions is elucidated. The linear stability of the flow to transverse perturbations is also examined in the CF case only. The results indicate that the flow, which is already unstable in the rigid-wall limit, is further destabilized as a result of the coupling between the fluid and underlying flexible wall.     

Increasing the Accuracy of Measurements of Air Flow Velocity with an Acoustic Anemometer

The physical principles of the operation of an acoustic anemometer are considered. An improved model of the anemometer channel, which takes into account the thickness of the waveguide-air duct walls is described. The results of a calculation of the reflection coefficient of the open end of a waveguide with rectangular flanges for one of the normal modes when there is an air flow are presented. The acoustic pressure field on the wall of the anemometer channel is calculated and the effect of the wall thickness on the choice of the optimum acoustic anemometer parameters is estimated.     

直齿圆柱齿轮三种齿厚参数的微量关系及应用

固定弦齿厚、公法线长度与跨棒距是描述齿轮齿厚的三种参数,本文就这三种齿厚参数的特点及适用范围进行了讨论,通过分析三种参数的微量关系,推导出它们之间相互转换的计算列式,得出了三个常见压力角条件下三种齿厚参数的微量关系图,并给出了微量关系图的具体应用示例。基于三种齿厚参数微量转换关系列式及微量关系图,可在已知一种齿厚参数微量的条件下,非常高效地得到另外两种齿厚参数的微量值,为工程应用提供了便利。     

新型环保纸蜂窝夹芯复合材料研究

目的依据包装缓冲设计及动力学理论分析新型环保纸蜂窝夹芯板的最佳厚度。方法通过平压实验、弯曲实验、抗冲击实验和单点吊挂实验分析蜂窝纸板的各项力学性能。结果平压实验时,压溃过程呈先后顺序,其压力-位移曲线呈双峰形态。在复合材料中间部位施加压力时,压力可达板自重的0.75倍以上,70~110 mm厚的板均能承受30 kg的大软体冲击(冲击高度为500 mm),满足墙体抗冲击性能标准;厚度小于90 mm的墙板,其损坏情况为孔洞周围石膏板被压溃,表现为轻微损伤;厚度大于90 mm的墙板,其力学性能良好。结论墙板的最佳厚度为90 mm。     

内外齿形件旋压成形时圆角成形质量研究

目的研究离合器毂旋压成形时不同参数对过渡圆角处填充效果的影响规律。方法使用DEFORM-3D软件对内外齿旋压成形过程进行数值模拟,采用正交实验分析了预制坯壁厚、预制坯内径、芯模与预制坯之间的摩擦因数和旋轮与预制坯之间的摩擦因数对旋压成形时材料流动的影响,以轴截面的内齿过渡圆角饱和度Sr作为评定指标,获得最优工艺参数组合。结果 4个成形参数对材料流动的影响程度为:预制坯壁厚影响最大,其次是预制坯内径,摩擦因数对轴截面的内齿过渡圆角饱和度影响不明显。由正交试验结果获得最优工艺方案为:预制坯壁厚为2.4 mm,预制坯内径为153.2 mm,芯模与预制坯间的摩擦因数为0.06,旋轮与预制坯间的摩擦因数为0.06,可获得最好的圆角填充效果。结论通过改变预制坯壁厚和预制坯内径,可以有效提高旋压成形内外齿形件过渡圆角处的填充效果。     

Optical properties of small-bore hollow glass waveguides

Hollow glass waveguides with a 250-μm i.d. have been fabricated with a liquid-phase deposition technique that uses silica tubing as a base material. The losses of the 250-μm-bore guide measured at CO(2) laser wavelengths are as low as 2.0 dB/m. The straight losses for the hollow guides are in good agreement with theoretically predicted losses as a result of the nearly ideal structure of the guides. It is also shown that the guides have low bending losses, a nearly pure-mode delivery, and good high-power laser transmission. By proper design of the dielectric thickness, the guide is also able to deliver Er:YAG laser energy with a low loss of 1.2 dB/m for the 320-μm-bore waveguide. Because the hollow glass waveguide is very flexible and robust, it is quite suitable for medical applications.     

动静轴结构旋翼轴载荷分离仿真分析与试验研究

动静轴结构旋翼轴是一种具有抗弹击能力的新型直升机旋翼轴构型,拟对自主设计的鼓形花键动静轴结构旋翼轴和柔性联轴节动静轴结构旋翼轴进行载荷分离特性研究。利用有限元软件对这2种动静轴结构旋翼轴的载荷分离系数进行仿真分析,并开展多通道加载试验加以验证。结果表明采用7 mm壁厚静轴时动静轴结构旋翼轴的载荷分离系数相比采用4 mm壁厚静轴时明显提高;柔性联轴节动静轴结构旋翼轴的综合载荷分离系数为77.37%,略高于鼓形花键动静轴结构旋翼轴的76.33%。研究结果可为直升机动静轴结构旋翼轴的设计提供指导。     

A slab optical waveguide with negative effective thickness

Two new asymmetric slab optical waveguides with a left-handed media (LHM) cover or substrate are studied. The effective thickness is derived by using normalized waveguide parameters. An analytical method is then proposed to calculate the universal effective thickness. We show that negative effective thickness exists in the waveguide with a LHM substrate, unlike in conventional waveguide or other LHM waveguides studied previously. However, for the waveguide with a LHM substrate, the shape of high-order mode behaves like that of a traditional slab waveguide, and neither the fundamental mode nor the other higher order modes have the novel phenomena of negative effective thickness. Both TE and TM modes are discussed.     

The passive optical properties of a silicon nanoparticle-embedded benzocyclobutene polymer waveguide

The passive optical properties of a silicon nanoparticle-embedded benzocyclobutene (BCB) waveguide were investigated. The silicon nanoparticles, of a size varying from 6 to 25?nm, were prepared by vapor condensation. The transmission modes and losses were examined by the prism coupler and cut-back methods. A He-Ne laser beam with a wavelength of 6328?? was used to measure the effective index and thickness of the waveguide. Laser light could be efficiently coupled into the BCB waveguide when the embedded Si nanoparticles were smaller than 6?nm. The film thickness and effective index of the Si-embedded BCB waveguide were measured to be 1.825?μm and 1.565, respectively. The optical transmission losses of the pure BCB and Si-embedded ridge waveguides measured by the cut-back method were 0.85 and 1.63?dB?cm(-1), respectively. Although the optical loss was increased by the embedded Si, the disturbance of the output contour was quite small. This result demonstrates that the nanoparticle-embedded polymer waveguide may be used for optoelectronic integrated circuits.