蠕墨铸铁在铁道车辆制动系统中的应用研究

在分析车辆制动器摩擦温度场的基础上 ,研究蠕墨铸铁在铁道车辆制动系统中的使用性能 ;研究结果表明 ,在车辆制动器服役条件下 ,摩擦速度与接触压力的提高 ,摩擦副的摩擦系数显著降低 ,磨损率显著增加 ;在所研究的不同石墨形态的铸铁中 ,蠕墨铸铁不但具有低而稳定的磨损率 ,而且具有高而稳定的制动性能 ,是制造车辆制动器部件的合理选材。     

多通管塑挤胀形工艺的力学分析

讨论了以聚氨酯橡胶棒为胀形介质，采用塑挤胀形复合工艺把无缝管坯一次成形为多通管成品的加工方法，分析了多通管塑挤胀形过程，提出了“应变样条”分析法，进而分析了典型剖面上应力应变状态，讨论了成形力间应具备的合理的数值关系，以使变形区处于最有利于变形的超高的静水压力和合适的偏应力状态，获得尽可能长的支管。     

混合盐法制备TiB2/Al复合材料的研究现状

由于TiB2/Al复合材料优良的性能,使其在航空航天和汽车制造等行业中具有广阔的应用前景。本文从混合盐法的原理、有效形核相等方面进行了阐述与分析,对材料的组织、性能和热处理进行了简要介绍,对材料的主要问题和现有解决方法作了分析。     

High temperature corrosion behavior of arc-sprayed aluminum coatings on steel

Aluminum coatings were sprayed on the substrate of steel Q235 by arc spraying. The test samples of Q235, Al coatings and Al coatings with seal coat were placed in box type electric resistance furnace at 400, 500,600, 650 ℃ when their oxidation behaviors were studied. And their oxidation kinetics curves were protracted. Microstructure, microhardness, bond strength and distribution of section elements were investigated by optical microscope(OM), Vickers microhardness instrument, electric tensile test machine and EPMA. Al coatings and Al coatings with seal coat can enhance the oxidation-resistance of substrate under 500 ℃. The latter has the best corrosion resistance. The coatings can't protect the substrate against oxidation above 600 ℃. After a long time corrosion there is enriched oxygen element at interface.     

硬质合金堆焊层经热处理后的耐磨性研究

对B、C、N共渗层、碳化钨型硬质合金(D707)堆焊层、高碳高铬铸铁型硬质合金(D618)堆焊层等几种不同表面处理工艺,经相应热处理后的腐蚀磨损性能进行了研究。结果表明,两种硬质合金堆焊层经850 ℃空冷、850±5 ℃油淬+400 ℃回火后,均具有较高的硬度和优异的耐腐蚀磨损性能,且简化了表面处理工艺。     

用DSPCF分光光度法测定钯

在室温下以硝酸为介质,钯与DSPCF形成有色络合物,其表观摩尔吸光系数ε_(520)=1.2×10~4,络合物组成为Pd(Ⅱ):DSPCF=1:2。其特点是在室温下发生显色反应,当加入HNO_3使介质达1.75N时,只有Pd(Ⅱ)—DSPCF红色络合物不褪色,可用于铂钯二次精矿等的测定。     

捷联惯性制导系统的电路设计

通过对捷联惯性制导与平台惯性制导之间差异的分析，讨论了在进行捷联惯性制导系统的电路设计时所应注意的问题，在此基础上，用C32 DSP和可编程逻辑器件，设计了一个捷联惯性制导系统的电路。     

Ti-23Al-17Nb合金激光切割工艺研究

对一种金属间化合物Ti-23Al-17Nb合金的激光切割性进行了初探。试验结果表明只要工艺参数适当，可获得较好质量的切口。切缝质量可以满足随后激光拼焊的要求。     

Si及变质处理对Mg2Si/Mg复合材料的影响

分析了Mg-Si二元合金直接原位形成Mg2Si/Mg复合材料的过程,研究了Si含量以及变质处理对复合材料组织和性能的影响。试验结果表明,随着合金中Si含量的增加,合金的流动性降低,复合材料中原位Mg2Si的数量增多,树枝晶形态更为发达;对优化的Mg-8Si合金,进行混合稀土(MM)和Sb变质处理,可明显改善Mg2Si的形态和分布,但Sb变质的效果要好于MM。合金经质量分数为1.2%的Sb变质处理后,Mg2Si以颗粒状均匀分布在Mg基体中,从而使复合材料具有较好的耐磨性。     

Experiment and simulation study of 3D magnetic field sensing for magnetic flux leakage defect characterisation

Magnetic flux leakage (MFL) testing is widely used to detect and characterise defects in pipelines, rail tracks and other structures. The measurement of the two field components perpendicular to the test surface and parallel to the applied field in MFL systems is well established. However, it is rarely effective when the shapes of the specimens and defects with respect to the applied field are arbitrary. In order to overcome the pitfalls of traditional MFL measurement, measurement of the three-dimensional (3D) magnetic field is proposed. The study is undertaken using extensive finite element analysis (FEA) focussing on the 3D distribution of magnetic fields for defect characterisation and employing a high sensitivity 3-axis magnetic field sensor in experimental study. Several MFL tests were undertaken on steel samples, including a section of rail track. The experimental and FEA test results show that data from not only the x- and z-axes but also y-axis can give comprehensive positional information about defects in terms of shape and orientation, being especially advantageous where the defect is aligned close to parallel to the applied field. The work concludes that 3D magnetic field sensing could be used to improve the defect characterisation capabilities of existing MFL systems, especially where defects have irregular geometries.