Si-Al COATING ON PURE MOLYBDENUM SUBSTRATE AND ITS CYCLIC OXIDATION BEHAVIOR

The halide-activated pack cementation method is utilized to codeposit aluminum and silicon on Mo substrate. Emphasis is placed on the microstructure and elevated-temperature oxidation resistance of coatings. The results show that hexagonal Mo (Si, Al)2 as a main phase and a little amount of the lower disilicide Mo3Si3 was formed on Mo substrate through the halide-activated pack cementation method. The resultant Si-Al coating on Mo substrate exhibits excellent cyclic oxidation resistance. The excellent cyclic oxidation resistance of the coatings is attributed to the formation of alumina on the coatings during the oxidation.     

EFFECT OF ANNEALING TREATMENT ON THE STRUCTURE OF CdS FILMS

The effect of annealing treatment on the structure of CdS films was investigated. The cadmium sulfide thin films were prepared by chemical bath deposition, and were annealed at nitrogen atmosphere at different temperatures. The films were characterized by SEM and XPS (X-ray photoelectron spectroscopy). X-ray photoelectron spectroscopy was used to examine the chemical states on the CdS films surface. It was found that thermal annealing could produce large grains of CdS thin films, remove the air contamination and reduce the oxygen content on the CdS films surface. Therefore, the CdS films changed more uniform and smoother surface after thermal annealing.     

Wetting kinetics of SiC nanoparticle reinforced Sn-Pb eutectic solders

SiC nanoparticles reinforced eutectic Sn-Pb solder were prepared by mechanical mixing method. Reactive wetting of the resultant composite solders on Cu substrates was investigated using real time, in-situ visualization of the triple-line movement. It was found that spreading rates of all solder pastes in this work do not obey Tanner's law of non-reactive spreading. SiC nano-particles slow down both the pre-melting and post-melting spreading rates of composite solder pastes. As the content of SiC nano-particles increase, the melting point of composite solders decrease, and the spreading time of molten composite solder pastes increases.     

纳米复合Ti-B-N薄膜的结构和摩擦学性能

研究了射频等离了体辅助化学气相沉积（PCVD）技术获得的Ti-B-N薄膜的组织结构和力学性能。结果发现，B元素的加入使薄膜中出现TiN纳米晶和BN非晶（nc-TiN／a-BN）的复合结构，其硬度显著高于TiN薄膜，最高可达40GPa。用球盘式摩擦磨损实验考察了薄膜的磨损特性。结果表明：与TiN薄膜相比，Ti-B-N薄膜抗磨损性能有显著提高，磨损机制与TiN薄膜不同，摩擦系数较TiN稍高。     

改善“最终形状成形”的经济性

改善“最终形状成形”的经济性美国国民机械公司ＲｏｂｅｒｔＪ．ＳｃｈｉｌｉｎｇＷｉｌｉａｍＲ．Ｐｅｒｒｙ１“接近最终形状成形”的优越性利用多模递进式成形机由金属盘料来冷锻生产零件已被广泛接受。这种加工与切削、铸造或锻造等相比较具有下列明显的优点：①降低...     

溅射气氛中O2／Ar比及热处理对直流反应磁控溅射法制备玻璃基TiO2薄膜结构与亲水性的影响

在工作气压为0．80Pa的氧氩气混合气氛下，改变氧与氩的流量比(O2／Ar：0．10，0．20，0．30)，在预先镀10nm左右SiO2的普通玻璃基片上用直流(D．C．)磁控溅射法制备了300nm左右的TiO2薄膜试样。离线在500℃、氧气氛下对试样热处理2h。用X射线光电子能谱(XPS)和X射线衍射仪(XRD)分别研究了试样热处理前后的表面元素组成、离子状态和物相组成，用接触角分析仪测试了试样在紫外光(UV)照射后的水润湿角。     

A STUDY ON ALUMINIDE COATINGS ON TiAl ALLOYS BY PACK CEMENTATION METHOD

1. IntroductionIntermetallic compound TiAl is expected to be one of the candidates for high temperature systems such as aircraft engines because it has a high specific strength at elevatedtemperatures[1,2]. However, there are two major drawbacks with intermetallic compoundTiAl as an engineering material: one is its poor room temperature ductility and the otheris the poor oxidation resistance above 800xi. The former has been generally overcomeby modification of the microstructure using ternar…     

TENSILE STRENGTH AND CREEP RESISTANCE OF Mg-9Al-1ZnBASED ALLOYS WITH CALCIUM ADDITION

1. IntroductionIn the paJst decade cast magnesium alloys have enjoyed a renaissance in many manu-facturing industries, especially the automotive and electronic ind.stri.s[1--4]. However, theuse of magnesium alloys for engineering applications is still restricted to a few structuralparts although they offer lightweight, high stiffness, excellent machinability and the bestalternative fOr weight reduction[4]. The principal technical challenge to the widespreaduse of magnesium castings in structu…     

ASTUDY OF VALENCE OF YTTRIUM IN Y_2O_3 Mo CATHODE

１．ＩｎｔｒｏｄｕｃｔｉｏｎＡｓａｎｅｗｋｉｎｄｏｆｒａｒｅｅａｒｔｈｍｏｌｙｂｄｅｎｕｍｃａｔｈｏｄｅｍａｔｅｒｉａｌ,ＭｏＹ２Ｏ３ｉｓｅｘｐｅｃｔｅｄｔｏｓｕｂｓｔｉｔｕｔｅｒａｄｉｏａｃｔｉｖｅＷＴｈＯ２ｃａｔｈｏｄｅｍａｔｅｒｉａｌｓｉｎｔｈｅｆｕｔｕｒｅ．Ｍｏ４ｗｔ％Ｙ２Ｏ３ａｌｌｏｗｓ,ｒｅｌａｔｉｖｅｔｏＭｏＬａ２Ｏ３〔１２〕（ｗｈｉｃｈｈａｓｂｅｅｎｗｉｄｅｌｙｓｔｕｄｉｅｄｓｉｎｃｅ１９７０ｓｉｎｏｒｄｅｒｔｏｓｕｂｓｔｉｔｕｔｅＷＴｈＯ２ｃａｔｈｏｄｅｍａｔｅｒ…     

钛合金铸件中残余应力的研究

目前钛合金铸件已广泛地应用在各种工业部门中。因此,对影响铸件质量的诸因素须进行更加深入的研究。在铸件中,不利因素之一是在铸件的冷却过程中产生残余应力。内部热应力是由于表面和内层冷却的不均匀性(顺序性)引起的(图1)也是由于铸件具有不同截面引起的。