K4104合金渗Al涂层抗高温氧化性能研究

采用料浆法在K4104合金表面进行热扩散渗铝,经1000℃×200h高温氧化性试验,用扫描电镜观察氧化后涂层的表面形貌。结果表明,渗Al涂层在氧化过程中已转变成连续致密的-αAl2O3氧化层和富铝的-βNiAl化合物层,使基体合金得到有效地保护,渗Al涂层具有良好的抗高温氧化性能。     

Ti与含Ti或B中间合金对铝晶粒细化效果及抗高温衰退能力的影响

对比研究了电解加钛和含钛或硼中间合金对铝的晶粒细化效果及抗高温衰退能力的影响.结果表明,电解加钛和Al-5Ti中间合金在熔体温度较低时具有较好的晶粒细化效果,但随着熔体温度的升高,细化效果均迅速衰退;电解加钛再熔配加Al-4B中间合金可在熔体温度为720℃时获得最佳的细化效果,随着熔体温度的升高细化效果有所衰退,但衰退速度较慢;在加入Al-5Ti的同时加入Al-4B中间合金可明显提高Al-5Ti的晶粒细化效果和抗高温衰退能力,但效果不如电解加钛加Al-4B中间合金;Al-5Ti-1B中间合金具有最强的抗高温衰退能力,随着熔体温度的升高,晶粒不但不粗化反而有所下降,当熔体温度高于900℃时,才出现衰退现象.对试验结果及晶粒细化机制进行了分析.     

钛钼合金电极在酸性介质中的电化学研究

采用交流阻抗和光电化学等测量方法研究了钛钼合金电极在0.2mol.L-1硫酸和0.2mol.L-1盐酸溶液中的电化学行为。交流阻抗测试结果表明,随着形成钝化膜的极化电位的增加,合金电极的阻抗增大,Mo在合金中的含量达到20%时,电极的阻抗模值|Z|0.05达到最大值;光电流循环伏安测量结果表明合金电极在阳极极化过程中显示阳极光电流,光电流iph随阳极极化电位增大而增加,表明电极表面膜呈n型半导体性质。     

铸造Al-Si合金中Sr与B间反应产物的研究

通过观察不同Sr,B含量时Al-Si合金中枝晶α和共晶Si形态与大小的变化，考察了Sr,B间的交互作用，采用X射线能谱仪对反应产物进行了分析。研究表明反应产物呈现两种不同类型：当Sr含量在0.025-0.030,B含量在0.028-0.036（质量分数，％）范围内时，二者间交互作用形成细小的SrB6化合物颗粒相，数量很少，存在于枝晶α中心；但当合金中Sr和B含量高于此范围时，形成Sr,B原子比接近3：4的Sr-B化合物，颗粒尺寸大、数量较多，且大多出现在共晶区。Sr-B化合物的形成消耗了大量的Sr和B,削弱了二元素的变质效果，导致了Sr,B间的互毒化行为。该化合物的形成为Sr,B间互毒化机理提供了直接证据。     

粉末混合方法和粉末粒度对钨重合金性能的影响

钨重合金因具有高密度、高塑性、高强度和高韧性，被广泛用于辐射防护等方面。钨重合金是由钨、镍、铁、铜粉末在真空和(或)氢气炉中液相烧结而成，在1500℃的液相烧结温度下，获得高密度合金。但是，高密度并不意味着其物理性能优异，物理性能对加工变化十分敏感。这些变化因素的研究包括烧结温度、烧结时间、烧结气氛、粉末性能和热处理温度，但却忽视了粉末混合方法和粉末粒度的影响。此项工作的目的就是研究粉末混合和粉末粒度对90W-7Ni-3Fe和92.5W-5.25Ni-2.25Fe重合金塑性和微观组织的影响。 粉末由钨、3m羰基镍和4.5m羰基铁组成。…     

Investigation of Creep Feed Grinding Parameters and Heat treatment Effects on the Nickel-base Superalloys

The Nickel base Superalloys are the most famous complicated and useable of Superalloys to make hot zone components of the gas turbines. The complicated dimensional tolerances, specially at the root of the blade show importance of grinding processes at the production of blades root. The prediction of the effect of machining parameters on the soundness of component surface strengthening for reaching to a suitable surface finishing and avoiding from crack formation at the work part during machining operation often is not easy and feasible so needs to more industrial investigation.This research is about frame 5 blade designed by GE and made from Superalloy IN738LC has been investigated. The formation of a plastically deformed and heat affected zone during grinding of Superalloy IN738LC with a high depth of cut but slow work speed (creep feed grinding) was investigated. Parameters such as work speed, depth of cut and radial dressing speed have been considered as variables and their effects have been studied. During experimental performed, the voltage and current of motor measured and power and special energy calculated.Some samples heat-treated (of the 1176℃ for 1 hr under neutral argon gas and cooling rate of 15℃/min up to 537℃ and then air cooling) to study grains recrystallization. Other samples have been created from the roots of blades and then coated by Nickel to measure boundary layer micro-hardness. The results show that increasing work speed leads to increasing the use power. Increasing the depth of cut, by increasing material removal rate, and the radial dressing speed, by decreasing power, lead to decreasing special energy. The temperature created by grinding lead to decreasing plastic deformation and boundary layer formation. When the radial dressing speed changes from 1 to 0.6μm/rev and other parameters are kept unchanged the roughness of surface increases and the special energy decreases. Sufficient dressing is very essential in limiting the width of the molten zone to few micrometers. As a result, it was found that local melting at contact spots to be a rather common mechanism during grinding of superalloys, lead to so-called white layers which can easily be observed on metallographic cross sections.     

Ti、Mo、W、Cr及其合金镀层与超硬磨料之间结合性能的研究

本文在研究金属与超硬磨料之间作用的基础上，讨论了实现镀层与磨料形成强力结合的条件，为高性能超硬工具的制造提供了理论和实践依据。     

氯化物熔盐中Nd^3＋在液体Ga电极上还原的电化学行为

本文利用循环V-A法(CV)研究了Nd~(3+)在液体Ga电极上还原的电化学反应动力学。结果表明,Nd~(3+)在Ga电极上的还原是分步进行的。第一步在较高的电位扫描速度下为扩散控制的可逆电荷传递反应,即Nd~(3+)+e?Nd~(2+);在电位扫描速度较低时,随后的化学反应为第一步反应的控制步骤,即Nd~(3+)+e?快Nd~(2+)+mCl→慢NdCl_m~(2-m)。第二步为不可逆的电荷传递反应,即沉积的金属Nd与Ga合金化,Nd~(2+)+2e→Nd(Ga)。估算了该反应的标准反应速度常数为7.0×10~(-3)cm/s。     

钠,锶变质铝硅合金机理的研究

通过对工业用铝硅类合金中硅相在变质前后形态的金相和扫描电镜观察,结合近年来国内学者的有关研究结果,对钠和锶的变质行为进行了分析,认力共晶硅的变质主要是由于孪晶分枝生长和共晶α相封锁硅枝晶的侧面生长所致。     

Sm-Fe合金磁致伸缩薄膜

磁致伸缩合金、形状记忆合金和压电陶瓷是在微型机器人上所用致动器的重要功能材料.作为超磁致伸缩材料人们所熟知稀土-铁系合金的有Tb-Fe、Sm-Fe和Terfenol-D等.