Reactive Hot Melts on the Basis of Polyester and Polyamide

Hot melts show many advantages over other adhesives, for instance, their lack of solvent and their very short setting time just by cooling. The weak point of hot melts in comparison to thermosetting resins is their limited thermal resistance. There is no doubt that the high performance hot melts on the basis of polyester and polyamide show a better heat performance than the widely-used rubbery hot melts. Nevertheless, it is true that the thermal resistance is limited by the melting point of the hot melt. To improve the heat performance, without losing the favourable hot melt properties, crosslinkable hot melts have been created. For the example, copolyamide/blocked isocyanate blends, it can be shown that crosslinkable hot melts are achievable in a wide range of reactivities. After curing, which takes place during the bonding process, these hot melts withstand temperatures of over 220°C even if the melting point of the initial hot melt was 100°C.     

数学形态学在数字图像处理中的应用研究

传统边缘检测算法由于对噪声敏感,难以准确提取图像边缘,导致图像处理效果不佳.基于传统数学形态学算法中结构算子的方向性和尺寸几何的基础上进行算法改进.针对抗噪型碰撞腐蚀形态学边缘检测算子结构元素特征,采用不同大小结构元素组合来提取边缘特征,有效保证了图像细节的同时去掉较大噪声点.根据结构元素的方向性,利用同向结构元素图像的匹配来检测各边缘信息,确保不同向边缘信息的完整度.通过比较文本改进算法与传统的边缘检测算法对图像边缘检测效果表明:本文提出的改进算子在处理较大图像边缘检测时具有更快的检测速度,且图像边缘光滑,细节清晰,具备了更强的抗噪性能.     

用双层辉光等离子法在钛表面制备的Ti-Pd合金层性能研究

采用双层辉光等离子冶金技术在纯钛表面制备了Ti—Pd合金层。其深度大约为90μm，Pd含量呈梯度变化，并出现了TiPd3，TiPd2，Ti2Pd3，Ti3Pd5，TiPd，Ti4Pd等6种化合物相和Pd相。合金层在100℃的NaCl饱和溶液＋HCl溶液以及40℃的8．6％H2SO4溶液中的耐缝隙腐蚀性能优于Ti0．2Pd合金；在室温80％H2SO4的溶液中，腐蚀速率仅为0．682mm／a，是Ti0．2Pd合金的18．2％：在室温30％HCl的溶液中，表面Ti—Pd的腐蚀速率仅为0．004mm／a，是Ti0．2Pd合金的12．5％。     

高耐蚀性热镀锌板的钝化处理工艺探讨

介绍了热镀锌板钝化膜的形成机理 ;针对攀钢热镀锌板出现白锈、黑斑等问题 ,分析了钝化液pH值、添加剂及操作条件对钝化膜质量的影响 ,同时提出了改进热镀锌板耐蚀性能的措施     

医用钴基合金的组织结构及耐腐蚀性能

以锻造CoNiCrMo，CoCrMo和CoCrMoC台会为研究对象，通过金相观察，XRD分析和耐腐蚀试验，研究了3组合金在不同热处理条件下的显微结构，相成分及在Hi同溶液中的耐腐蚀性能。结果表明：2组锻造合金的再结晶温度都是1000℃，且晶粒尺寸随着固溶温度升高和时效时间延长而逐渐变大。3组试样在NaCl溶液中为钴基合金典型的阳极极化曲线；在Hanks’溶液中均有一个二次钝化行为，且锻造CoNiCrMo合金的二次钝化区域较窄，而其他2组合金则较宽；在含柠檬酸三钠的溶液中过钝化电位降低，柠檬酸盐的存在降低了含金的耐腐蚀性能。热处理对合金的耐腐蚀性能影响不大。     

(Short communication) Degradation of corrosion resistance of Zircaloy-4 in LiOH aqueous solution

To investigate the degradation of corrosion resistance of Zircaloy-4 in LiOH aqueous solution, SIMS (secondary ion mass spectrometry) analysis was performed to examine the profiles of Li~ , K~ , and OH~- in oxide layers formed in the same concentration (0.1 mol/L) LiOH and KOH solutions. Even though the oxide layers have an equal thickness, the penetration depth of K~ is shallower than that of Li~ , and the penetration depth of OH~- corroded in KOH solution is also shallower than that corroded in LiOH solution. It shows that the diffusion of OH~- into oxide layer is accompanied by the corresponding cation. The difference of degradation effect of LiOH and KOH solutions on the corrosion resistance of Zircaloy-4 was discussed.     

Effect of binder-phase modification and Cr3C2 addition on properties of WC-IOC0 cemented carbide

For production of fine-grained and corrosion-resistant tungsten carbide (WC) based cemented carbides, addition of chromium carbide (Cr₃3C₂) in small amounts is standard practice. No systematic study, however, has been made of the effects of large additions (maximum 6 wt % ) of Cr₃C₂ as a substitute for tungsten carbide. This study focuses on the effect of hard-phase substitution by C₃C₂ in WC-1OCo cemented carbide. An attempt is also made to modify the binder metal cobalt by partial or complete substitution of nickel. Specimens were prepared using the standard liquid-phase sintering process and were tested for sintered porosity, mechanical properties, corrosion resistance, and microstructural parameters. Results confirm the findings of earlier workers regarding grain refinement and improvement of mechanical properties upon the addition of small amounts (<2 wt%) of Cr₃C₂. Modification of the binder phase improves indentation fracture toughness and corrosion resistance. Addition of Cr₃C₂ independent of the binder type improves corrosion resistance.     

Corrosion resistance of austenitic stainless steel separator for molten carbonate fuel cell

STS310S and SC-STS310S (simultaneously co-deposited chromium and aluminum onto 310S austenitic stainless steel substrate by pack-cementation process) were used as separator materials on the cathode side of a molten carbonate fuel cell. With the STS310S, corrosion proceeded via three steps; a formation step of unstable corrosion product, a protection step against corrosion until breakaway, and an advance step of corrosion after breakaway. The final corrosion product was LiFeO₂ and the loss of mass was 6.5 mg/cm² after a corrosion test of 480 hr at 650°C. The SC-STS310S showed more effective corrosion resistance, however, than did common STS310S. There was especially no corrosion loss on the SC-STS310S after the 480 hr corrosion test. It is anticipated that it will be very useful as an alternative separator on the cathode side off the MCFC in the future.     

基于改进串联合闸电阻的变压器励磁涌流抑制研究

在利用合闸电阻抑制变压器轻载或空载合闸时产生励磁涌流的基础上,提出一种在合闸电阻上串联适当电容器的改进方法。该方法在原有的合闸电阻上串联电容,通过适当选取电容的容值,以减少励磁涌流的大小,加快励磁涌流的衰减速度。将该方法与分相合闸技术相结合,可最大程度实现变压器励磁涌流的抑制。仿真实验结果验证了该方法的可行性。