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1.
The corrosion behaviour of melt spun amorphous and nanoquasicrystalline Zr70Pd30 and Zr80Pt20 alloy ribbons has been investigated using potentiodynamic polarization study in NaCl, H2SO4 and NaOH solutions at different concentrations. The amorphous and nanoquasicrystalline alloys show better corrosion resistance than Zr in all the solutions studied. Both the alloys are susceptible to chloride attack and pitting has been observed. Complete passivation has been observed in H2SO4, while gradual break down of passivating layer occurs in NaOH. In general, nanoquasicrystalline state in both the alloys shows better corrosion resistance than amorphous state in all the solutions studied.  相似文献   

2.
Chromium passivation and lacquering are typically used to improve the corrosion resistance of tinplate in packed food. In this work, the nature of the chromium passivation layer formed during dip or CDC passivation treatments, as a function of operational parameters, and its influence on lacquer adhesion, was investigated using electrochemical polarisation, XPS, Auger and lacquer peel-off tests. It was found that dip passivated tinplate provide the best lacquer adhesion, and that the adhesion on CDC treated tinplate could be improved by buffering or lowering the pH of the chromium (VI) solution.  相似文献   

3.
工程金属材料/零件的表面完整性及其断裂抗力   总被引:3,自引:2,他引:1  
工程金属材料的力学性能取决于其显微组织结构。至于对那些由表面起裂引发宏观脆性断裂(诸如疲劳断裂、应力腐蚀与氢脆断裂等)的断裂抗力性能,则首先取决于零件的表面完整性。文中提出了狭义的表面完整性定义,介绍了与这类宏观脆性断裂抗力性能有直接关系的表面完整性参量,诸如表面显微组织结构参量、表面(层)力学性能参量、表面(层)残余应力参量以及表面应力集中参量等。表面强化工艺技术就是通过改变零件表面完整性使这类宏观脆性断裂抗力的性能获得提高。  相似文献   

4.
The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion.  相似文献   

5.
为改善钛的抗菌性能和生物活性,采用微弧氧化(MAO)技术在纯钛表面制备了锌掺杂TiO_2涂层(M-Zn)、锶掺杂的TiO_2涂层(M-Sr)和锌锶共掺杂TiO_2涂层(M-Zn/Sr)。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对制备的涂层的组织结构和成分进行分析;采用平板计数法研究了涂层的抗菌性能;利用细胞荧光染色和甲基噻唑基四唑(MTT)的方法探究了细胞在材料表面的生长状况。结果表明:形成的TiO_2涂层都是典型的多孔结构,主要由金红石和锐钛矿相组成,锌、锶的掺杂对涂层形貌影响不大。M-Zn/Sr涂层中锌、锶的原子数分数分别为7.9%和1.7%。M-Zn及M-Zn/Sr涂层大肠杆菌展现了良好的抗菌性能,抗菌率接近100%。M-Zn、M-Sr和M-Zn/Sr均能促进成骨细胞增殖,M-Zn/Sr涂层具有抗菌和细胞增殖的双重功能。  相似文献   

6.
Susceptibility to localised corrosion is strongly affected by heat treatments performed on Al-Zn-Cu-Mg alloys. In order to study how galvanic coupling between intermetallics and matrix is affected by solution heat treatment, AA7075-T6 and solution heat treated AA7075 have been characterised by means of scanning electron microscopy and scanning Kelvin probe force microscopy. Solution heat treatment strongly increased the Volta potential difference between the intermetallics and the surrounding matrix showing a strong increase in galvanic coupling. This is explained by Zn and Mg enrichment of the matrix caused by dissolution of strengthening particles during solution heat treatment.  相似文献   

7.
There is a correlation between the microstructure and the mechanical behavior of ultrafine-grained face centered cubic (fcc) metals processed by equal-channel angular pressing (ECAP). It is shown that the saturation yield strength is related to the maximum dislocation density according to the Taylor equation and, in addition, the value of the parameter α in the Taylor equation is strongly affected by the stacking fault energy because of different geometrical arrangements of dislocations within the grains. It is also demonstrated that the ductility of Cu processed by ECAP decreases with increasing strain but at extremely high strains the ductility is partially restored due to the recovery of the microstructure.  相似文献   

8.
余淑媛  郑麟  韩飞 《金属学报》2018,23(2):235-240
血管炎是一类可引起血管非特异性炎症和坏死的自身免疫性疾病。按血管受累的大小分类,包括了小血管炎、中等血管炎及大血管炎。抗中性粒细胞胞质抗体(ANCA)相关性小血管炎(AAV)属于小血管炎的范畴,主要包含了肉芽肿性多血管炎(GPA),显微镜下多血管炎(MPA)和嗜酸肉芽肿性多血管炎(EGPA)。它们可累及全身不同脏器,活动期异常凶险,治疗不及时可致高死亡率。本文简要综述AAV的发病机制及治疗进展。  相似文献   

9.
本文分析了设计部门研发图纸后,在编制明细时如何将研发明细转换为“ERP-BOM”,以及PDM系统研发明细更改后如何自动、精确地将这些改动传递给“ERP-BOM”,使之做到同步更改,使PDM与ERP系统之间实现信息集成,保证产品数据的一致性、完整性、唯一性和共享性.  相似文献   

10.
羟基磷灰石(HA)由于具有良好的生物相容性和骨组织诱导性,被认为是替代人体硬组织的一种很好的生物医用材料,但其溶解度较高,降低植入体的长效性,而将氟渗入HA晶格中能提高HA结构稳定性并降低其溶解性,将硅掺入HA晶格中能有效地提高HA的生物活性,因此含氟羟基磷灰石(FHA)和含硅羟基磷灰石(Si-HA)成为了新兴的改性材料。介绍了羟基磷灰石(HA)、含氟羟基磷灰石(FHA)以及含硅羟基磷灰石(Si-HA)的性能特点以及涂层的制备技术,重点阐述了采用激光熔覆技术制备生物涂层的研究现状以及本课题组的研究进展,指出了目前研究中存在的不足,并展望了生物涂层今后的研究和发展趋势。  相似文献   

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