锌浴中合金元素对热镀锌层上锌花的影响

综述了锌浴中合金元素对热镀锌层上锌花的结构和表面形貌的影响以及合金元素对锌花形成的作用机制,如抑制形核机制、晶体学机制以及表面能和表面张力机制;分析了合金元素对锌花镀层耐腐蚀性能和力学性能的影响.     

合金元素对液相锌流动性的影响

液相锌的流动性不仅直接影响合金的铸造性能，而且还对热浸锌镀层厚度控制有着十分重要的意义。在液相锌中加入各种微量的合金元素可以提高流动性，从而改善热浸锌镀层的镀覆效果和表面质量，也能提高液相锌的压铸填充性能。为此，主要综述了用于热浸锌的常见合金元素(Pb、Bi、Sn、Sb、Al、Mg、RE、Ni)以及部分用于压铸锌合金的合金元素(Al、Mg)对液相锌流动性的影响。     

冷却工艺对镀铝锌钢板锌花尺寸与组构的影响

为提升厚规格镀铝锌板的表面质量、控制锌花尺寸、增强镀层观赏性,使用热浸镀模拟机组在厚规格钢板基体上制备了不同镀后冷却工艺的铝锌镀层(55.0Al-43.4Zn-1.6Si),使用扫描电子显微镜(SEM)及能谱仪(EDS)观察了镀层表面和截面的微观形貌及元素分布,探讨了镀后冷却工艺对铝锌镀层锌花尺寸、表面及截面形貌与结构的影响。结果表明:对于厚规格镀铝锌钢板,在600-380℃温度区间增大镀后冷却速率可降低锌花尺寸、增加枝晶取向的多样性,从而增强锌花立体感;同时可细化镀层组织、减小镀层表面二次枝晶间距,并降低金属间化合物层厚度。冷却过程中,600-520℃温度区间是镀层组织形核长大的关键阶段,因此在该温度段增大冷却速率可较为显著地减小锌花尺寸、细化镀层组织、提升镀层观赏性。     

关于减少热浸锌锌耗的探讨

实验表明,热浸锌的锌耗,存在于锌渣、锌灰和合金镀层的超厚.正确选择材料,严格控制工艺过程,添加铝和锌液复盖物以及保证予处理质量,可以有效控制锌耗.     

热浸镀铝锌液中Ti添加量对镀层性能的影响

目前,热浸镀铝锌液中Ti含量对镀层锌花尺寸及镀层质量影响的研究还不够深入.向热浸镀锌铝液中添加不同含量的Ti,对DX51D+ AZ冷轧钢板热浸镀铝锌.采用扫描电镜及能谱仪分析镀层形貌及成分;采用盐雾试验分析镀层的耐蚀性;测试了镀液成分、镀层质量及镀层弯曲变形性;研究了Ti含量对Zn-55 ％Al合金镀层性能的影响.结果表明:镀液凝固组织及镀层组织均为富铝相、富锌相、富硅相及Al-Zn-Fe-Si化合物相;Ti含量对铝锌镀层组织结构无明显影响,当钛含量为0.034％,0.046％时镀层组织中含Ti,并且存在于富铝相中;Ti在热镀铝锌的镀层形成过程中提供了更多的异质形核点,有助于减小锌花尺寸;Ti对镀层的成形性无明显影响,但可显著提高镀层的耐腐蚀性.     

热浸镀55%Al-Zn-1.6%Si合金钢板镀层表面形貌及组织特征研究

采用光学显微镜、SEM、EDS等实验手段,研究了Ti元素对热浸镀55 ％Al-Zn-1.6％Si板的镀层表面形貌、元素分布、成分组成、横截面相组成体积比的影响.结果表明:无添加Ti元素的1#镀铝锌产品表面锌花尺寸偏大且不均,Al、Zn、Si等元素在表面分布规律不明显,镀层总厚度在15～17 μm之间,其中外镀层15μm,内镀层1.8μm,镀层截面由约65％的富铝相+35％的富锌相组成;添加Ti元素的2#镀铝锌产品镀层表面光泽比1#亮丽,立体感效果显著,锌花尺寸也更加细碎均匀,Al、Zn、Si等元素呈现较明显的规律分布,镀层总厚度在24.3～26.7 μm之间,其中外镀层24.8μm,内镀层1.6 μm,镀层截面组织由约76.2％的富铝相+22.7％的富锌相及少量的富硅相组成.     

热浸镀涂层材料的进展

本文综述热浸镀材料的性能及特点。并详细介绍近年来的锌铝合金热浸镀技术的发展情况,以及热浸锌镍合金镀层的性能和特点。最后,还扼要叙述了热浸铅锡镀层的近况。     

活性钢热浸锌镍合金镀层工艺与性能

热浸锌镍合金镀层技术是解决活性钢热镀锌问题的有效方法。分析了在常规热镀锌浴中加镍后,镍在镀层形成过程中的作用,以及对镀层工艺、性能的影响。结果表明,热浸锌镍合金镀层具有良好的粘附性能和耐腐蚀性能,表面光亮、均匀,减少了超厚现象,硬度和耐磨性有所提高。     

锌浴中镍含量对热浸锌镀层厚度的影响

应用SEM,EPMA等方法研究了锌浴中镍含量对热浸锌镀层厚度的影响,试验结果表明,当锌浴中镍含量小于0．12％（wt)时,镀层随镍含量增加而减薄,当镍含量大于0．12％时,镀层则随镍含量增加而增厚,在热镀锌生产线上对0．10％以下的不同镍含量锌浴的应用结果表明,为了兼顾不同产品对最低镀层厚度的要求,镍含量可在0．04％－0．10％间选择,这时由于减少镀层超厚,节锌效果明显。     

影响热浸镀锌钢板锌花形成的因素

使用低碳钢板进行热浸镀锌试验,利用扫描电镜观察了含铅镀锌层的微观形貌与组织,根据Zn-Pb相图,对含铅镀层的凝固过程进行了分析.通过试验研究了冷却速度对锌花大小的影响,当冷却速度在0～25 K/s时,随冷却速度增大,锌花尺寸从10 mm逐渐减小到1 mm,并分析其原因,得出:铅影响锌结晶过程和锌花形态,锌枝晶生长方向取决于形核位置,冷却速度对锌花尺寸有显著影响,锌花尺寸与冷却速度呈负指数增长的关系.     

负偏压对Be上磁控溅射离子镀Al膜结构影响的研究

以Be为基体，采用磁控溅射离子镀的在其上镀制Al膜，研究了负偏压对Al膜微结构的影响；研究表明，不加基体负偏压，Al膜在（111）面择优生长；随着基体负偏压升高Al膜在（111）面择优生长趋势减北，Al膜在（200）面生长趋势加强；当基体负偏压超过150V后，Al膜在（111）面择优生长的趋势又得到加强。晶粒在低负偏压时随负偏压增加而细化，当较高的负偏压引起基体温度升高时，此时晶粒又变大了。     

Features of surface structuring of silicon (100) crystals by microwave plasma treatment in different gas environments

The laws of the effect of microwave plasma treatment modes on the surface nanomorphology of silicon single crystals with crystallographic orientation (100) with a natural oxide coating are studied. Model mechanisms of surface nanostructuring during plasma treatment in gas environments with different selectivities for the heterostructure material of the substrate are discussed.     

Microstructure and mechanical properties of multi-constituent superlattice coatings

Superlattice nitride coatings with four different layer constituents, i.e., ZrN, MoN, NbN and AlN, were synthesized using an unbalanced closed-field magnetron sputtering coater. At small superlattice modulation periods, both MoN and AlN layers adapted to the cubic B1 structure due to a template effect, and the coatings exhibited a strong (2 0 0) preferred orientation. Increasing the modulation period above a critical value led to the formation of hexagonal MoN and AlN layers with diminishing (2 0 0) preferred orientation. These microstructure changes were reflected in the coating mechanical properties. Relatively high hardness and Young's modulus values were obtained at small modulation periods, which decreased dramatically above the critical modulation period. The effects of substrate bias on the layer crystallographic structure, coating preferred orientation and mechanical properties were similar to those of the modulation period.     

热镀锌钝化板锌花形貌对耐蚀性的影响

采用光学显微镜和扫描电子显微镜(SEM/EDS)对热镀锌钝化板锌花形貌及不同时间中性盐雾试验后热镀锌钝化板锌花的腐蚀形貌进行了分析,研究了热镀锌钝化板表面形态、微区成分及锌花形貌对其耐蚀性的影响.结果表明,热镀梓板有典型的锌花形貌,明亮和灰暗锌花区的形貌差异大;灰暗锌花区无规则密布的球形颗粒为Pb及Al元素的富集,光亮锌花区平整性良好,较少元素富集;明亮锌花区的耐蚀性明显优于灰暗锌花区,腐蚀在球形颗粒处优先发生,由颗粒处向整个锌花区域扩展.     

Effect of Crystallographic Anisotropy on Micro EDM Process

In this paper, experiments are conducted by machining from different crystallographic orientations of monocrystalline silicon, and the effects of crystallographic orientation on the micro electrical discharge machining (EDM) process are discussed. The results demonstrate that the machining speed and surface roughness are varied when crystallographic orientation changes. The surface roughness is seen to vary by as much as twofold with crystallographic orientation, while the ratio between the maximum and minimum values of material removal rate is 1.76. The unique material removal mechanism of micro EDM enhances the effects of crystal anisotropy on micro electrical discharge machining process.     

Optical technique for the in situ study of orientation and structure changes accompanied the plastic deformation of polycrystalline specimens of aluminum

An optical technique for in situ color orientation mapping of the surface of a ductile Al polycrystal is suggested. It is based on the effect of anisotropic scattering of white light by quasiperiodic etching relief depending on the crystallographic grain orientation. The technique includes recording of digital color orientation maps with a computer-connected web camera. The color of the image of individual segments of the specimen’s surface is determined by the character of the quasiperiodic relief, which depends on the crystallographic orientation of these segments. In situ color orientation mapping of the whole polycrystalline surface allows studying orientational changes during plastic deformation.     

Synthesis and Characterization of Cr-ZrO2 Composite Coating Formed by DC and Pulse Electrodeposition

Chromium–zirconia (Cr-ZrO₂) composite coatings were developed on low-carbon steel substrate by direct current (DC) and pulse electrodeposition (PED) technique with different pulse frequency and duty cycles to enhance mechanical properties of the coating. The phases and morphology of the coating were studied with scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Surface mechanical properties were analyzed by micro-hardness and ball-on-plate wear study. It was found that pulsing and higher pulse frequencies refine the matrix and increase the ZrO₂ content in the coating. Apart from fine structure and dispersion, crystallographic orientation of Cr matrix also gives its effect on hardness and wear properties. Wear mechanism was found to be mainly abrasive in nature with little adhesive inclination in case of DC deposition.     

Fracture toughness analysis of anisotropic nickel-based single crystal superalloys at high temperature

The purpose of this article is intended to study the fracture toughness of anisotropic nickel-based single crystal superalloys at elevated temperature by compact tension (CT) specimen in experiment method. The special attention is put on the orientation and temperature dependence of mechanical properties of single crystal as well as thickness effect of specimen. The experimental results show that crystallographic orientation and temperature have much complex effect on fracture toughness. The difference of fracture toughness of single crystal for different crystallographic orientation at low temperature is much greater than that at high temperature. The nickel-based single crystal specimen may merely become less anisotropic with the increase of the ambient temperature seems as more multi-slip action appears. The fracture mode of the specimens transfers from brittle to ductile as the temperature increases; also, the fracture toughness of single crystal for the same orientation becomes larger with the decreasing of the thickness of single crystal specimen.