共查询到18条相似文献,搜索用时 156 毫秒
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钴对含硅钢镀锌层的组织和生长动力学的影响 总被引:1,自引:0,他引:1
利用扫描电镜及波谱,研究锌浴中的钴对Q235和Q345钢热浸镀锌层组织及其生长动力学的影响.结果表明:锌浴中含0.075%(质量分数)钴时,能完全抑制Q235镀层组织发生硅反应性;而对于Q345,则需要在锌浴中加入0.3%钴才能部分抑制硅反应性;在锌浴中加入少量的钴后,镀层组织中疏松ζ层转变成与液相直接接触的富钴ζ相和由消耗δ相生成的致密ζ相;致密的ζ相层阻止液相和δ相的直接接触;富钴ζ相可容纳大约0.25% Si,避免在固-液界面产生硅的富集,液相通道消失,从而抑制含硅钢热浸镀锌过程中硅反应性的产生. 相似文献
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研究了低碳钢短时间浸入锌液后铁、锌之间的反应过程。结果表明,低碳钢与锌液的反应层产物主要包括靠近内侧呈柱状晶生长的紧凑、致密δ-Fe Zn10相和外侧较为疏松的ζ-Fe Zn13相,稳定生长阶段疏松的ζ-Fe Zn13相生长占据主导地位。铁、锌的反应产物生长过程符合抛物线生长规律,生长初期主要受界面反应控制,而在稳定生长阶段,主要受液锌原子扩散控制。铁、锌产物层从钢基体到表面依次为过饱和α-Fe、Γ1-Fe5Zn21、δ-Fe Zn10、ζ-Fe Zn13和表层的η-Zn。 相似文献
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探讨了锌淬时镀锌层组织形成的过程,结果表明:在锌淬过程中依次形成Fe-Al相、δ_1相、ζ相和η相。由于锌淬时较一般热镀锌时钢件入锌浴的温度高,有利于形成Fe-Al化合物,增加合金层的铝含量,因而提高了镀锌层的粘附力。 相似文献
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研究了四种不同Mn含量的铁锰二元合金在450℃液锌中的腐蚀行为,探讨了Mn对铁锌反应的影响规律。结果表明,铁锰二元合金在液锌中的腐蚀属于溶解性腐蚀。随着锰含量的增加,腐蚀速率有较大变化。含锰量为10wt%的合金,其腐蚀速率为5.79×10-3g.cm-2.h-1,含锰量为15wt%的合金,其腐蚀速率为3.64×10-2.gcm-2.h-1。锰含量为10wt%时,腐蚀产物由致密的δ相层和块状的ζ相层组成,致密的较厚的δ相层的存在,降低了铁锌反应速率,合金表现出较好的耐液锌腐蚀能力,而锰含量为15wt%时,腐蚀产物由大量疏松的颗粒状ζ相分布在液锌相中组成,疏松的组织恶化了合金的耐液锌腐蚀能力。 相似文献
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研究了电脉冲处理对热镀锌镀层组织和生长影响。采用冷轧钢板在460℃条件下得到不同电脉冲处理参数不同浸镀时间的镀层组织,结果表明,未经电脉冲处理试样铁锌互扩散较快,δ相和ζ相同时生长,且随时间延长ζ相呈起伏式生长,合金层的组织变得不连续且存在疏松。电脉冲处理后试样合金层的生长均受到抑制,生长比较稳定。在180 s浸镀时间内,δ相层的组织晶粒度均匀致密,ζ相的连绵式生长消失,与δ相和η相相界面变得非常连续,厚度明显减薄,由83.5μm减薄到70μm以内。经电脉冲处理后,合金层的生长由扩散和界面反应联合控制转变为仅受扩散控制。 相似文献
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Xuping Su Peng Xu Ya Liu Jianhua Wang Hao Tu Changjun Wu Haoping Peng 《Surface & coatings technology》2012
In the galvannealing process, a galvanized sheet is given an annealing treatment to transform the zinc coating to the Zn–Fe intermetallic coating through diffusional reactions. In the present work, a mathematical model for predicting the growth of ζ (zeta), δ (delta), and Γ (gamma) during the galvannealing process has been developed by using fundamental diffusion data. The primary diffusion mechanism is the movement of zinc through the multiphase of the Zn–Fe intermetallics. The values of iron content in the coating were predicted and compared to the data obtained from experimental studies. With the increase of galvannealing temperature, the growth rate of the δ phase increases, while the growth rate of the ζ phase decreases. At the same iron content in the coating, the thickness of the Γ phase layer is thicker at a higher temperature. The new type of galvannealing process of first high annealing temperature and then low annealing temperature is validated as a better galvannealing process, which should be a range of practical application. The simulated results agree well with experimental observations, and the model can be utilized to optimize the galvannealing parameters. 相似文献
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The purpose of this work is to identify the influence of zinc bath temperature on the morphology and the thickness of hot-dip galvanizing coating. Hot-dip galvanizing samples were prepared at temperatures in the range of 450-530 °C in steps of 10 °C and at different immersing time. The samples were characterized by using scanning electron microscopy/energy dispersive X-ray analysis. When the galvanizing temperature ranges from 450 to 470 °C, the coating has a coherent and compact ζ layer on the top of a δ layer. ζ phase coexists with liquid zinc pocket around 480 °C. It was found that the coating thickness reaches maximum at 480 °C. When the temperature is above 500 °C, the coating changes to be primarily δ phase. 相似文献
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Suwat Ploypech Yuttanant Boonyongmaneerat Petch Jearanaisilawong 《Surface & coatings technology》2012
Crack initiation and propagation behaviors in the intermetallic layers of galvanized coatings subjected to bending loads are characterized and numerically simulated. Coating structure of galvanized steel prepared by hot dipping at 450 °C is a laminate composite consisting of δ, ζ, and η phases, with an infinitesimal layer between the coating and steel article speculatively representing a Γ phase. The specimens were deformed in a four-point bending configuration, and the evolution of cracks was investigated as a function of bending angles. Through-cracks were found to develop in the δ layer of the coatings after thermal cooling due to thermal stresses and propagate toward the outer surface under increments of bending loads. Finite element simulations of galvanized steels were subsequently developed with an initial crack tip located in the δ layer to determine the controlling parameters of the crack propagation and to assess the coatings' fracture parameter, critical far field stress, and stress distributions. The analysis highlights the enhancement of fracture resistance of the galvanized coatings owing to the presence of the ζ layer. 相似文献
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INFLUENCE OF SILICON IN STEELS ON GALVANIZED COATINGS 总被引:1,自引:0,他引:1
C.S. Che J.T. Lu G. Kong Q.Y. Xu J.H. Chen 《金属学报(英文版)》2006,19(2):85-90
After steel sheets (0.37wt%Si) pre-electroplated with a thin layer of pure Fe were immersed in molten zinc for various time, the change in the microstructure of the galvanized coating on the steel and the change of α-Fe/Г interface were studied. The EDS (energy dispersive sepectroscopy) resuits show that excessive silicon accumulates on the surface of the steel substrate due to the low solubility of silicon in the Г layer after the Fe layer is depleted by the increasing growth of the compound layers. With the movement of α-Fe/Г interface towards the substrate by the Fe/Zn reaction, silicon-rich α-Fe peels off from the substrate and breaks into particles. The particles, much like an inert marker in a Kirkendall effect experiment, move towards the δ layer through the Г layer because silicon-rich α-Fe can not be adsorbed in the Г layer. On reaching the 8/F interface, the particles quickly dissolve in the δ layer, and accelerate its growth, resulting in the gradual disappearance of the Г layer. At the same time, the normal coating is quickly changed into coatings typical of reactive steels as silicon dissolved in the δ layer soon diffuses toward the ζ layer. A similar process may happen in the initial stage of galvanizing reactive steels on a small scale, although it is hard to be observed. 相似文献
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采用热扩散法在GH738合金表面制备出Al-Si渗层。通过X射线衍射仪(XRD),扫描电镜(SEM),能谱仪(EDS)分析了Al-Si渗层形貌、厚度、物相组成和元素分布;采用显微维氏硬度计测定了渗层的硬度;采用静态增量试验方法,在1200℃,对Al-Si渗层试样和GH738镍基合金基体进行了100 h的恒温抗氧化性能测试。结果表明,Al-Si渗层厚度可达120μm,渗层为明显的双层结构,外层为Al-Si层,内层为互扩散层;渗层物相组成主要为NiAl和Ni2Al3以及少量Cr3Si;渗层表面硬度达到900 HV0.1左右,约为基体的3.5倍;Al-Si渗层氧化动力学曲线满足抛物线规律,氧化速率常数为0.0987 mg2·cm-4·h-1,表面形成比较致密的Al2O3保护膜,其高温抗氧化性能较基体提高了约5倍。 相似文献
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为了提高冷轧镀铝锌钢板表面晶花质量,在连续热浸镀生产线制备了4种不同成分的Al-Zn-Mg-Si镀层样板,采用体视显微镜、扫描电镜、电子探针、X射线衍射仪和电子背散射衍射等方法,研究了Mg含量对镀层凝固组织和耐腐蚀性能的影响。结果表明:随Mg含量的增加,镀层晶花尺寸先减小后增大,耐腐蚀性先降低后增高;在Mg质量分数为1.0%时,镀层质量最佳,晶花细小均匀,平均晶粒尺寸为1.2 mm,镀层截面组织中含质量分数为68.3%的富铝相、质量分数为26.1%的富锌相、少量富硅相和富镁相,在60 d内的平均失重速率为0.05 g/(m2·d)。 相似文献
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镀锌钢在红沿河大气环境中的腐蚀行为 总被引:2,自引:0,他引:2
目的研究镀锌钢在红沿河地区SO2和Cl-含量较高的大气环境中的腐蚀行为与机理。方法根据GB/T 6464—1997将制备好的试样在红沿河核电厂进行现场暴晒试验,分别暴晒4、12、18、24个月后取回试样。利用失重分析、X射线衍射(XRD)和扫描电镜(SEM)等技术,观察与分析试样暴晒后的腐蚀产物。结果镀锌钢腐蚀失重随暴晒时间的延长而线性增加;随着暴晒时间的延长,锌镀层表面形成的腐蚀产物成分变化不大,以Zn12(SO4)3Cl3(OH)15·5H2O和6Zn(OH)2·Zn SO4·4H2O为主;腐蚀产物随暴晒时间的延长逐渐增加,产物形貌略有变化,以球状和针状为主。暴晒18个月后,腐蚀产物分为双两层,内层致密,外层疏松;暴晒24个月后,腐蚀产物厚度稍有增加,疏松层向致密层转变。结论 SO2与Cl-是镀锌钢在红沿河地区的大气腐蚀过程的主要影响因子。镀锌钢表面形成的腐蚀产物对锌镀层的保护作用较差。 相似文献
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目的探索铝化物涂层的制备工艺,研究其是否能有效抑制铅液对CLAM钢的腐蚀。方法用配制的渗剂对CLAM钢进行包埋渗铝,并通过随后的热扩散和原位氧化处理,在CLAM钢表面制备铝化物涂层,研究不同渗铝时间和热扩散时间对涂层厚度的影响。通过静态氧化试验和铅液腐蚀试验,分别评价铝化物涂层的抗氧化性能及其与铅液的相容性,采用XRD、SEM和EPMA分析涂层的相组成以及铅液腐蚀前后的微观形貌和元素分布。结果包埋渗铝+热扩散+原位氧化处理制备的铝化物涂层主要由约30μm的FeAl相层和约70μm的α-Fe(Al)固溶体层组成。在热处理过程中,由于Al和Fe的互扩散现象,涂层中的Fe-Al相依次经过了Fe2Al5、FeAl2、FeAl、Fe3Al和α-Fe(Al)的转变。在600℃空气中静态氧化120 h后,铝化物涂层试样氧化质量增量为0.028 mg/cm2,比CLAM钢的氧化质量增量降低了1个数量级,铝化物涂层使CLAM钢的氧化动力学曲线由直线规律转变为抛物线规律。经550℃铅液腐蚀600、1800 h后,铝化物涂层的腐蚀质量增量分别为0.058、0.077 mg/cm2,仅约为CLAM钢的1/120。CLAM钢表面产生了疏松多孔的铁氧化物层,而铝化物涂层没有发生明显的腐蚀,但是腐蚀1800 h后,随着表面铝含量的不断消耗,Al2O3层厚度逐渐减小。结论铝化物涂层具有良好的抗氧化性能及与铅液的相容性,能够有效抑制铅液对CLAM钢的腐蚀。 相似文献