稳恒磁场下Ni-W合金镀膜的制备与耐蚀性

研究了施加稳恒磁场(0~1 T)对电镀Ni-W合金的影响。测定不同方向、不同强度稳恒磁场下的电流效率、合金组成及镀层的耐蚀性,并用扫描电镜和X射线衍射对镀层的微观形貌及结构进行了观察和分析。对实验结果进行了分析讨论,找出稳恒磁场对这些性能指标的影响规律。结果表明:与不施加磁场相比,施加磁场后镀层的表面更均匀、细致、平整;镀层的含钨量上升:当B⊥J,B=1.0 T时,含钨量上升了约7%;当B∥J,B=1.0 T时,含钨量上升了约9%;镀膜的非晶化程度增强;镀膜的耐蚀性提高;但Ni-W合金电镀的电流效率降低。     

防锈油膜在5% Na2SO4溶液中的半导体导电行为

采用电位—电容法及Mott-Schottky分析技术研究了自腐蚀电位条件下防锈油膜在5% Na2SO4溶液中失效过程的导电机制转变行为.防锈油膜在5% Na2SO4溶液中的失效过程存在半导体导电特征，随着浸泡时间的延长，防锈油膜从浸泡初期的p型半导体转变为n型半导体，转变过程中，防锈油膜中出现两个空间电荷过渡层.随着浸泡时间的延长，防锈油膜中的空间电荷层厚度皆逐渐减小，载流子密度则逐渐增加，并且计算了不同转变时期防锈油膜中的电子给体（ND）和电子受体（NA）密度大小.     

MICROSTRUCTURAL STUDY OF Fe-Cr-Al/Al COMPOSITE COATINGS DURING OXIDATION AND SULFIDATION AT 900 ℃

The microstructure of a composite coating system, which was composed of an inner layer of Fe-Cr-Al and an outer layer of aluminum, was studied after it was respectively oxidized and sulfurdized at elevated temperatures. Apart from the Al2O3 scale formed on the surface, the microstructure of the composite coatings exposed at 900℃ in air for 4h was a three-layer structure. The first layer consisted of a solid solution of Cr and Fe in α aluminum and an intermetallic compound FeAl3, while the second layer was a single phase of the aluminide and the third layer still remained the same appearance as the original Fe-Cr-Al coating.The microstructural observation of the specimen tested at 850-900 ℃ at low oxygen pressure and high sulfur pressure for 576h revealed that the surface coatings of the specimen had transformed into a duplex structure containing an outer layer and a thicker aluminide layer beneath. X-ray diffraction results showed that the out layer was composed of Al2S3 and Al2O3 and that AlCrFe2 was the main phase composition of the aluminide layer, with a few of Al2S3 and Al2O3 accompanied.     

基于特征相似论的复杂虚拟样机系统置信度评估

基于相似理论提出了基于特征相似思想的系统可置信度评估方法，拓展了特征建模思想的相似元和相似系统的概念，最后对无法进行原型试验的深海开采系统升沉补偿装置的虚拟样机进行了置信度评估。     

Influencing factors on elastic-plastic deformation of multi-layered surfaces under sliding contact

Stress distribution in the gradient multi-layered surface under a sliding contact was investigated using finite element method(FEM). The main structure parameters of layered surface discussed are total layer thickness,layer number and elastic modulus ratio of layer to the substrate. A model of multi-layered surface contact with rough slider was studied. The effect of the surface structure parameters on the elastic-plastic deformation was analyzed.     

脉冲偏压对电弧离子镀非晶氧化钛薄膜性能的影响

用脉冲偏压电弧离子镀技术在玻璃基片上制备均匀透明的氧化钛薄膜，通过改变脉冲偏压幅值，考察其对氧化钛薄膜性能的影响。结果表明，沉积态薄膜为非晶态；脉冲偏压对薄膜性能有明显的影响。随偏压的增加，薄膜厚度、硬度和弹性模量均先增大后减小，前者峰值出现在-100-200V负偏压范围，后两者则在-150～250v范围：-300v偏压时的薄膜硬度最高；达到原子级表面光滑度，RRMs为0．113nm，薄膜折射率也最高，在λn=550nm达到已有报道的最高值2．51，此时薄膜具有最好的综合性能。文中对脉冲偏压对薄膜性能的影响机理也进行了分析。     

ANALYSIS ON THE BEHAVIOR OF PRECIPITATES IN ULTRA-THIN HOT STRIP OF PLAIN LOW CARBON STEEL PRODUCED BY COMPACT STRIP PRODUCTION

This paper investigated the mechanism of precipitation and its influence upon prop-erties of ultra-thin hot strips of low carbon steel produced by CSP techniques using experiment and thermodynamics theory. The experimental results show that there are lots of fine and dispersive precipitates in microstructures. By analysis, most of aluminum nitrides are in grains, while coexisted precipitates of MnS are along grain boundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3 in the core, while MnS is at the fringe of surface. The precipitation behavior of AlN and MnS in the hot strip is studied by thermodynamic calculation. At last, implica-tions between strengthening effect and techniques are analyzed using obtained solubility products.     

1Cr18Ni9Ti不锈钢半固态浆料的制备和轧制

研究了1Cr18Ni9Ti不锈钢半固态浆料的制备和轧制规律，结果表明：在本实验条件下，当搅拌时间为2—3min时，可以获得尺寸大小为10m-200μm、固相率为50％—60％的球状初生奥氏体的半固态浆料，便于从搅拌室底孔中放出，浆料可以实现顺利轧制，但球状初生固相颗粒与液相发生了分离，球状初生固相颗粒集中在轧材的心部，而液相偏聚在轧材的四周；经过一道次轧制，1Cr18Ni9Ti不锈钢半固态浆料轧制板材的常温强度比常规热轧板材的强度高，但延伸率下降。     

贝氏体相变机制的研究进展

简要地总结了清华大学贝氏体相变研究组在贝氏体相变领域的主要研究成果。包括以下方面 :①利用TEM、AFM、STM发现了钢及有色合金中的贝氏体超精细结构 ;②利用STM发现贝氏体表面浮突大多是由与超亚单元相对应的“帐篷型”小浮突群组成的 ;③利用TEM和STM证实了三维巨型台阶存在的普遍性和可动性 ;④发现钢中贝氏体碳化物在α/γ界面的γ侧形核并向奥氏体内生长 ;⑤概述了贝氏体的激发形核 台阶长大机制及其理论计算 ;⑥用前述相变机制解释了贝氏体的多层次复杂结构 ,以及上贝氏体、下贝氏体等不同形态的形成原因。     

Microstructure evolution in a large—grained TiAl alloy

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