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采用非平衡磁控溅射在GW93镁合金表面制备了镀C/Cr复合镀层,分析了不同本底真空度下在GW93镁合金表面进行非平衡磁控溅射镀C/Cr复合镀层的硬度、耐蚀性、膜基结合力,摩擦系数等.结果表明,非平衡磁控溅射镀C/Cr复合膜层,本底真空度在8.8×10-3~1.0×10-1Pa范围内,镀层硬度与本底真空度成反比,当其为8.8×10-3Pa时,镀层硬度最低为1397Hv0.05,镀层使基体自腐蚀电位提高到-0.940V,显著改善镁合金的耐蚀性,结合力最高可达8.11N,镀层的摩擦系数最低达到0.05.本底真空度对C/Cr复合镀层相组成没有显著影响,不同真空度下的C/Cr复合镀层均以非晶为主. 相似文献
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目前,对镁合金表面镍钨合金镀层的研究多为化学镀镍钨磷三元镀层,工艺复杂,能耗高.采用电沉积法在AZ91D镁合金制备镍钨镀层,采用场发射扫描电镜(FESEM)、能谱成分分析(EDS)和X射线衍射(XRD)对镀层的表面形貌和成分进行分析,用维氏硬度计测量镀层硬度,测量AZ91D镁合金及镀层在3.5 %NaCl溶液中极化曲线,并结合盐雾试验判定其耐腐蚀性,研究了镀液中钨酸钠含量对所得镀层性能的影响.结果表明:随着镀液中Na2WO4·2H2O浓度的增加,镀层钨含量不断增加,镍钨置换固溶体数量增加,从而起到提高镀层硬度和耐磨性、细化镀层晶粒、提高耐蚀性的效果;Na2 WO4·2H2O浓度超过65 g/L时,继续添加Na2WO4·2H2O对镀层优化作用减弱;当Na2WO4·2H2O浓度为75 g/L时,镀层钨含量为25.06%,硬度达483 HV,自腐蚀电位-1.124 V,自腐蚀电流10.80 μA/cm2,所制备的镍钨镀层对镁合金基体具有耐磨耐蚀保护作用. 相似文献
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镁合金Ni-B化学镀层具有高耐蚀性、高硬度、高耐磨性等特点,具有广泛的应用价值,过去对其研究不够.采用化学镀在AZ31变形镁合金表面制备了Ni-B镀层,研究了酸洗、活化、浸锌等基材预处理工艺对Ni-B化学镀层形貌及性能的影响.结果表明:CrO_3+KF酸洗对基材的腐蚀较轻,而采用CrO_3+HNO_3酸洗时基材腐蚀严重;HF和NH_4NF_2+H_3PO_42种活化作用的机理在于形成MgF_2的中间转换层,保护基材不被镀液腐蚀,HF活化后在基材表面形成了较大面积的MgF_2,活化能力更强,对基材的保护能力更好;浸锌工艺对镀层的性能有较大影响,二次浸锌后锌颗粒和锌层厚度都小于一次浸锌,Ni-B镀层更平整致密,硬度和结合力优于一次浸锌,显微硬度为458 HK,明显高于镁合金基材的硬度(77 HK),同时镀层的耐蚀性也有较大的提高. 相似文献
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用电镀的方法制备出Ni-纳米TiO2复合电镀层,讨论了表面活性剂、阴极电流密度、搅拌速率等对复合镀层硬度的影响并分析了纳米TiO2的加入对复合镀层硬度、耐蚀性的影响情况.结果表明,与纯镍镀层相比,Ni-纳米TiO2复合电镀层的硬度可提高90~190 HV;添加阳离子表面活性剂分散纳米TiO2所得复合镀层硬度最高,说明阳离子表面活性剂有利于纳米TiO2-Ni复合电沉积.浸泡试验表明,在硝酸溶液中复合镀层的腐蚀速率高于纯镍镀层的腐蚀速率,但远低于未镀覆钢板的腐蚀速率;极化曲线表明,与纯镍镀层相比,复合镀层的自腐蚀电位没有显著提高.说明在复合镀层中添加纳米TiO2不能改善其耐蚀性. 相似文献
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研究了在AZ31镁合金表面依次进行浸锌、化学镀镍、电镀铜、电弧离子镀Cr/CaN的复合镀膜工艺.结果表明,在此复合镀工艺条件下,可以在AZ31镁合金表面形成致密度高、结合强度好、耐蚀性好且硬度高的复合合金镀层.AZ31镁合金镀膜后的显微硬度形成一个梯度,由71 HK提高到2225 HK;耐蚀性明显提高,在3.5%NaCl溶液中腐蚀电位从-1481 mV提高到-382 mV. 相似文献
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为了提高铝材Ni-W-P镀层的耐腐蚀性,在镀液中加入La(NO3)3,在1060铝表面化学镀Ni-W-P合金层.采用电化学法和失重法分析了合金镀层的耐蚀性,采用扫描电镜观察合金镀层的形貌,采用X射线衍射仪分析了镀层的结构;研究了La(NO3)3含量对Ni-W-P镀层沉积速率、孔隙率、腐蚀速率、腐蚀电位、腐蚀电流、交流阻抗、维氏硬度等性能的影响;对镀层进行热处理,研究了热处理对合金镀层性能的影响.结果表明:当镀液中La(NO3)3质量分数为1.0%时,所得镀层的沉积速率最大,为65.7 g/(m2·h),维氏硬度最高,为80.3 HV,孔隙率最低,镀层的耐蚀性能最好,镀层包状物颗粒大小均匀、紧密、无缺陷;经100~500℃热处理后,镀层硬度有所提高,但耐蚀性有不同程度下降,经300℃热处理后,合金维氏硬度高达136 HV,是未热处理的1.7倍. 相似文献
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A. Abdel Aal 《Journal of Materials Science》2008,43(8):2947-2954
A phosphate–permanganate conversion coating was applied as the pretreatment process for AZ91D magnesium alloy substrate. Zn–Ni
alloys were electrodeposited onto the treated AZ91D magnesium alloy from sulfate bath. The morphology and phase composition
of the coatings were determined with X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The results reveal that
the conversion rate depends on pH of solution and treatment time. Salt spray and the electrochemical polarization testing
were applied to evaluate the corrosion performance of phosphate–permanganate and Zn–Ni coated alloys. It was found that Ni
content in deposit is a function of current density and bath composition. Zn–13 wt.% Ni coating provides very good corrosion
protective function to inner AZ91D magnesium alloy. Phosphate–permanganate treatment enhances the corrosion resistance of
Zn–Ni coatings. 相似文献
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不同表面处理工艺压铸镁合金涂层耐蚀性研究 总被引:3,自引:0,他引:3
为了研究不同表面处理工艺下压铸镁合金涂层的抗腐蚀性能,通过浸泡腐蚀和电化学腐蚀的方法,比较了微弧氧化和无铬化学氧化等表面处理试样的耐蚀性.结果表明,无铬化学氧化和微弧氧化处理能显著提高镁合金表面耐蚀性,而以微弧氧化处理更优;且两种处理方法覆盖层对孔洞、裂纹不敏感.根据交流阻抗图谱,拟合得到了微弧氧化、无铬化学氧化和未处理三种试样电化学腐蚀时体系的等效电路,拟合结果与实测结果吻合.XRD分析表明这两种处理方法得到的覆盖层中主体相均为Mg3Al2Si3O12等含硅的尖晶石型氧化物和Mg0.36Al2.44O4、MgAl2O4等不含硅的镁、铝复合氧化物,有利于提高镁合金耐蚀性. 相似文献
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To improve the wear and corrosion resistance of AZ91D magnesium alloy, Zr-based coating made of Zr powder was fabricated on AZ91D magnesium alloy by laser cladding. The microstructure of the coating was characterized by XRD, SEM and TEM techniques. The wear resistance of the coating was evaluated under dry sliding wear test condition at room temperature. The corrosion resistance of the coating was tested in simulated body fluid. The results show that the coating mainly consists of Zr, zirconium oxides and Zr aluminides. The coating exhibits excellent wear resistance due to the high microhardness of the coating. The main wear mechanism of the coating and the AZ91D sample are different, the former is abrasive wear and the latter is adhesive wear. The coating compared to AZ91D magnesium alloy exhibits good corrosion resistance because of the good corrosion resistance of Zr, zirconium oxides and Zr aluminides in the coating. 相似文献
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Qiang Wang Yaohui Liu Shijie Fang Yulai Song Dawei Zhang Lina Zhang Chunfang Li 《Materials Characterization》2010,61(6):674-682
The influence of yttrium on the corrosion residual strength of an AZ91D magnesium alloy was investigated detailedly. Scanning electron microscope was employed to analyze the microstructure and the fractography of the studied alloys. The microstructure of AZ91D magnesium alloy is remarkably refined due to the addition of yttrium. The electrochemical potentiodynamic polarization curve of the studied alloy was performed with a CHI 660b electrochemical station in the three-electrode system. The result reveals that yttrium significantly promotes the overall corrosion resistance of AZ91D magnesium alloy by suppressing the cathodic reaction in corrosion process. However, the nucleation and propagation of corrosion pits on the surface of the 1.0 wt.% Y modified AZ91D magnesium alloy indicate that pitting corrosion still emerges after the addition of yttrium. Furthermore, stress concentration caused by corrosion pits should be responsible for the drop of corrosion residual strength although the addition of yttrium remarkably weakens the effect of stress concentration at the tip of corrosion pits in loading process. 相似文献
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镁合金微弧氧化膜结构及耐蚀性的初步研究 总被引:14,自引:2,他引:14
空气中由于AZ91D镁合金耐腐蚀性差,影响实际应用.为了弄清腐蚀原因,增加应用效果,作者利用扫描电镜和X射线衍射分析了AZ91D镁合金表面微弧氧化膜的形貌、结构和相组成,并对氧化膜的耐蚀性作了初步试验分析.研究表明,AZ91D微弧氧化膜呈3层结构,外层氧化膜存在一些孔洞;中间层氧化膜疏松、具有较大厚度;内层氧化膜与基体金属结合紧密.氧化膜主要由MgO,MgSiO3,MgAl2O4,Mg3(PO4)2组成.经1周3%NaCl溶液浸泡试验,结果表明微弧氧化膜可以较大程度地提高AZ91D镁合金的耐蚀性,但氧化膜表面富含Si,P的颗粒是易发生腐蚀的电化学活性点,导致氧化膜发生局部腐蚀. 相似文献
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In this study, multilayered AlN (AlN + AlN + AlN) and AlN + TiN were coated on AZ91 magnesium alloy using physical vapour deposition (PVD) technique of DC magnetron sputtering, and the influence of the coatings on the corrosion behaviour of the AZ91 alloy was examined. A PVD system for coating processes, a potentiostat for electrochemical corrosion tests, X-ray difractometer for compositional analysis of the coatings, and scanning electron microscopy for surface examinations were used. It was determined that PVD coatings deposited on AZ91 magnesium alloy increased the corrosion resistance of the alloy, and AlN + AlN + AlN coating increased the corrosion resistance much more than AlN + TiN coating. However, it was observed that, in the coating layers, small structural defects e.g., pores, pinholes, cracks that could arise from the coating process or substrate and get the ability of protection from corrosion worsened were present. 相似文献
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YingLI FuhuiWANG HongweiHUO 《材料科学技术学报》2003,19(5):459-462
Magnesium coatings were fabricated on stainless steel substrates (1Cr11Ni2W2MoV) by a plane magnetron sputtering technique. The argon pressure and the substrate condition (including temperature and the substrate was rotated or fixed) were varied in order to evaluate the influence of the parameters on the crystal orientation and morphology of the coating. The corrosion behavior of the coatings in 1 wt pct NaCl solution was studied by electrochemical methods.The results showed that all coatings exhibited preferred orientation (002) as the argon pressure increased from 0.2 to 0.4 Pa. The morphologies of the coatings varied with the argon pressure and with whether the substrate was rotated or fixed. The open circuit potential of the coatings was more positive than that of cast AZ91D magnesium alloy.However, the immersion test in 1 wt pct NaCI solution showed that the corrosion rates of the coatings were higher than that of cast AZ91D magnesium alloy. 相似文献
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Surface coatings for improving the corrosion resistance and cell adhesion of AZ91D magnesium alloy through environmentally clean methods 总被引:1,自引:0,他引:1
Two different coatings, Mg-Al hydrotalcite and aragonite (CaCO3), were produced on die-cast AZ91D Mg alloy (Mg-9wt.%Al-1wt.%Zn) through environmentally clean methods. The corrosion resistance and human mesenchymal stem cell adhesion properties of the coatings on AZ91D were investigated. Results showed that through environmentally clean methods, both Mg-Al hydrotalcite and aragonite CaCO3 surface coatings could be produced on AZ91D surfaces. These coatings increased the corrosion potential and polarization resistance and decreased the corrosion rate of AZ91D in simulated body fluid. Both surface coatings also improved stem cell spreading and interaction in culture. Further long-term animal testing is suggested before these surface coatings can be recommended for use in clinical applications. 相似文献