低气压等离子喷涂TiO_2涂层的电学性能研究

本文利用改变低气压等离子喷涂(LPPS)TiO_2时工艺参数的方法,发现了TiO_2涂层还具有优良的电学性能。得出涂层的电导率与喷涂过程中TiO_2的氧分解量成比例增加,但涂层中的Ti_2O_3含量对电导率影响较大。涂层的光电流-电位特性依赖于涂层结构,当金红石形TiO_2涂层中含有适量的Ti_3O_5和Magneli相时,表现出最佳光电流-电位特性,并与光强度成正比例关系,若涂层全部由金红石形TiO_2或Ti_2O_3,Ti_3O_5和Magneli组成时,光电流-电位特性消失。     

镍基钎料接头中硼的扩散行为

对镍基钎料中硼元素在钎焊接头扩散区的扩散行为作了较系统的研究．采用Ｘ射线衍射分析，ＳＥＭ和ＥＤＸ等方法，证实了硼的扩散对形成优良的钎焊接头具有决定性的作用．试验表明；扩散区的硼以Ｍ３Ｂ２型存在，它的数量和形态受许多因素的影响．只有在等温凝固的结束阶段，硼的扩散才比较接近Ｆｉｃｋ定律．     

快速凝固Al-Cu-Si薄带钎料的制备及其性能

利用快速凝固技术制备了 3种低熔点Al Cu Si系带状钎料 ,并对其性能进行了分析 .结果表明 ,利用快速凝固技术可以制备低熔点Al Cu Si系带状钎料 ,Al30Cu9Si和Al2 0Cu10Si钎料都可以在温度低于 5 2 0℃以下焊接 ;退火后金属薄带能对折 180°而不折断 ,可以满足使用要求 ;快冷钎料比传统钎料有更好的流动性 .θ′相的析出是造成快冷钎料显微硬度增加的主要原因 ,快冷薄带经过退火处理后 ,θ′相转变成稳定的与基体非共格的θ相 ,可显著提高快冷薄带的塑性 .     

铝钎焊接头中Cu的腐蚀与扩散行为

应用X射线衍射仪、扫描电镜和能谱分析仪 ,研究了Al Si Cu钎料中Cu在真空钎焊接头中的腐蚀与扩散行为 .研究结果表明 ,真空钎焊后的接头仍然存在腐蚀问题 ,如点蚀和晶间腐蚀等 ,并且随着w(Cu)的增加腐蚀加重 .Cu在钎焊接头中以晶界扩散为主 ,且晶界扩散比晶内扩散快 .     

1760 型造纸机速度-张力控制系统的设计

为了解决现有１７６０型造纸设备在生产中经常出现的断纸或堆纸现象,进行了１７６０型造纸机速度－张力控制系统的设计,分析了速度－张力控制的作用及系统的组成,描述了系统的控制规律以及控制环节的参数整定．这为改造原有的造纸设备的控制系统提供了理论依据．     

Fe基非晶软磁合金的纳米晶化及磁性

研究了Fe78Si9B13,Fe73.5Cu1Nb3Si13.5B9,Fe74Cu1Mo2Nb1Si13B9三种非晶软磁合金在753～853K温度间等温退火1h后的纳米晶化行为和磁性,实验证明Cu,Nb和Mo元素的加入有助于提高晶化温度,稳定非晶组织.同时采用差热分析和X衍射仪分析了三种合金的晶化相,测量了其磁滞回线,结果表明1#,2#,3#合金分别在753K,813K,753K退火1h后可获得优良的综合软磁性能.     

用铝合金中间层连接Si_3N_4和低碳钢

利用Thermorestor-W焊接热模拟试验机,采用适当的焊接参数和工艺,能够用铝合金中间层固相扩散连接Si_3N_4和低碳钢。在连接温度下,铝合金Si_3N_4进入孔洞中形成机械连接,而铝合金与Si_3N_4连接的主要机理是铝与Si_3N_4发生固相反应生成AlN。当温度大于530℃时,铝合金/Si_3N_4界面Al,Si扩散层厚度基本上不随温度升高而变化。Si_3N_4/铝合金/低碳钢接头的剪切强度取决于铝合金/钢界面强度,且随扩散连接温度上升而增加。     

快凝锡基软钎料的浸润性研究

引入了快冷锡基软钎料的浸润性模型,并进行了计算处理．结果表明,经过快冷加工后,锡基软钎料的钎焊浸润角变小,浸润性得到了改善,钎焊接头强度有所提高;钎焊温度对浸润性影响很大,并随着温度的提高,液态快冷钎料的表面张力降低,浸润角随之变小．     

Effect of stoichiometry and Cu-substitution on the phase structure and hydrogen storage properties of Ml-Mg-Ni-based alloys

To improve the electrochemical properties of rare-earth-Mg-Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the alloys were studied. Nonsubstituted Ml_0.80Mg_0.20(Ni_2.90Co_0.50-Mn_0.30Al_0.30)_x (x=0.68, 0.70, 0.72, 0.74, 0.76) alloys and Cu-substituted Ml_0.80Mg_0.20(Ni_2.90Co_0.50-y Cu_y Mn_0.30Al_0.30)_0.70 (y=0, 0.10, 0.30, 0.50) alloys were prepared by induction melting. Phase structure analysis shows that the nonsubstituted alloys consist of a LaNi₅ phase, a LaNi₃ phase, and a minor La₂Ni₇ phase; in addition, in the case of Cu-substitution, the Nd₂Ni₇ phase appears and the LaNi₃ phase vanishes. Thermodynamic tests show that the enthalpy change in the dehydriding process decreases, indicating that hydride stability decreases with increasing stoichiometry and increasing Cu content. The maximum discharge capacity, kinetic properties, and cycling stability of the alloy electrodes all increase and then decrease with increasing stoichiometry or increasing Cu content. Furthermore, Cu substitution for Co ameliorates the discharge capacity, kinetics, and cycling stability of the alloy electrodes.     

Allowable variation of cold-rolled strip transverse profiles in high tension

The formation mechanism of the cold-rolled strip shape with high tension was studied. An advanced method to calculate the allowable variation of strip transverse profiles was established by the strip buckling criterion, which can be more properly used in cold rolling. With this method, the aim allowable variation of the product strip transverse profile and the required transverse profile range of incoming strips can be reached. Besides, this method has been successfully applied in a domestic tandem cold mill, and the transverse profile range of incoming strips suggested with this method is more practicable and complete. Consequently, the good performance is acquired.