Ce对Mg-9Gd-4Y-1Nd-0.6Zr合金微观组织和耐蚀性的影响

为获得高强耐蚀的镁稀土合金,采用扫描电镜、X射线衍射分析、腐蚀失重法、电化学阻抗和动电位极化等研究了元素Ce对Mg-9Gd-4Y-1Nd-0.6Zr合金微观组织和耐蚀性的影响。结果表明添加0.5% Ce后合金耐腐蚀性能较好,合金的腐蚀电流密度为不含铈合金的55.6%,腐蚀电位正移约141 mV。适量Ce元素的加入导致其他稀土元素在晶界处富集并呈网状分布,使第二相粒子尺寸变小,体积分数变大。     

A novel dual nickel coating on AZ91D magnesium alloy

Magnesium alloys covered with metal coating display excellent corrosion resistance,wear resistance,conductivity and electromagnetic shielding properties.The electroless plating Ni-P as bottom layer following the electroplating nickel as surface layer on AZ91D magnesium alloy was investigated.The coating surface morphology was observed with SEM and the structure was analyzed with XRD.Electrochemical tests and salt spray tests were carried out to study the corrosion resistance.The experimental results indi...     

时效时间对挤压Mg-10Gd-4.8Y-0.6Zr合金腐蚀性能的影响(英文)

采用浸泡实验和电化学分析,探讨时效过程中挤压Mg-10Gd-4.8Y-0.6Zr合金的腐蚀行为。结果表明:合金的腐蚀速率随着时效时间的延长而逐渐减小;合金抗腐蚀性能随着时效析出相的长大、粗化而逐渐提高;开路电位随着时效时间的延长而逐渐变正。由极化曲线可知,在时效处理中,阴极电位和阳极电流的平稳期发生改变,阴极电位随着时效时间的延长而增加(抑制效应),而阳极电流的平稳期随着时效时间的延长而降低(催化效应)。     

铸态与挤压态Mg-5Y-7Gd-1Nd-0.5Zr合金在5% NaCl水溶液中的腐蚀行为(英文)

在5%NaCl水溶液中通过浸泡和电化学测试研究铸态与挤压态Mg-5Y-7Gd-1Nd-0.5Zr镁合金的腐蚀性能。铸态和挤压态Mg-5Y-7Gd-1Nd-0.5Zr镁合金的平均晶粒尺寸分别为100μm和15μm。在腐蚀初期,铸态合金的腐蚀形貌为点蚀和少量丝状腐蚀,挤压态合金的腐蚀形貌为点蚀。挤压态合金的腐蚀速率大于铸态合金的腐蚀速率。包含稀土的第二相在合金中作为阴极,改善了合金的腐蚀性能。铸态与挤压态合金的腐蚀电位分别为-1.658V和-1.591V。探讨了铸态与挤压态合金腐蚀性能不同的原因。     

镁锆合金表面Ni-P非晶化学镀工艺研究

镁锆合金是一种轻质、高阻尼的新型合金,但耐蚀性极差.采用化学镀方法,系统研究了Mg-0.57Zr合金表面Ni-P非晶化学镀的预处理及施镀工艺.研究结果表明:1)采用复合酸洗,有利于提高镀层与基体的结合力、镀层的沉积均匀性和金属光泽度;2)直接化学镀镍比预浸锌后再化学镀镍的工艺方案,更利于提高镀速、降低镀层孔隙率;3)采用所推荐的化学镀工艺,获得了与基体结合力高、孔隙率低、耐蚀性较好的Ni-P非晶镀层,其平均镀速为11.44 μm/h,镀层硬度比合金基体提高10.7倍.     

Study on the Technology of Ni-P Electroless Plating on the Mg Alloy

Base on the analysis for the corrosion mechanism of the Mg alloys,the technology of Ni-P directly electroless plating on the Mg-10Li-1Zn alloys was studied.The effects of the pre-treatment on the morphologies of substrate and plating films were investigated,The result shows that Ni-P electroless plating could be divided two steps:the induction period and the rapid deposition period.The Ni-P film is amorphous structure:A excellent Ni-P coating can be obtained under the optimal parameter.The Ni-P coating can obviously improve the corrosion resistance of Mg alloy in variety environment.     

A homogenisation pre-treatment for adherent and corrosion-resistant Ni electroplated coatings on Mg-alloy AZ91D

Multi-step Ni electroplatings were applied to AZ91D following the development of a homogenisation pre-treatment. The Ni coating was well adhered, as verified by thermal shock testing, and provided corrosion protection in 3.5 wt.% NaCl for 74 h at a coating thickness of ∼15 μm. Being a cathodic coating, further protection in the presence of defects was not demonstrated herein, however realisation of quality Ni coatings on Mg is technologically important. To this end, achieving microstructural homogeneity on AZ91D is critical prior to plating or coating (such as electroless plating and chemical conversion coating) multi phase Mg-alloys.     

前处理工艺对镁合金化学镀Ni-P质量的影响

采用扫描电镜和性能检测的方法,分析了表调、活化和浸锌等前处理工艺对镁合金化学镀Ni-P质量的影响.结果表明,表调可使晶界凸出于α-Mg基体,降低镁合金的表面粗糙度,提高化学镀层的结合强度.活化及浸锌后,促进了化学镀的进行.按表调、活化、一次浸锌、退镀、二次浸锌的工艺进行前处理后实施化学镀,得到的Ni-P镀层致密、平整,与基体结合力强,有效提高了镁合金表面耐蚀性及显微硬度.     

镁合金无铬无氟前处理直接化学镀镍研究

采用磷酸为主要成分的溶液取代传统的铬酸加氢氟酸对镁合金进行活化处理,然后直接化学镀镍;用SEM/EDAX考察了无铬无氟前处理转化膜和化学镀镍沉积层的形貌、成分.结果表明,无铬无氟转化膜主要由磷酸镁组成,化学镀镍层表面较均匀、致密、无明显缺陷.经热处理后,镀层和基体的结合强度超过23 MPa.动电位极化测试结果表明,镀层体系的自腐蚀电位约为-0.36 V(SCE),有明显的钝化区间,对基体镁合金起到较好的防护作用.     

化学镀Ni-P和Ni-Cu-P合金耐蚀性研究

研究了硫酸铜加入量对化学镀Ni-Cu-P合金的镀层成分、组织及热稳定性影响,用中性盐雾实验和在20%H2SO4+20 g/LAl2O3溶液中的冲刷腐蚀实验研究了Ni-P与Ni-Cu-P合金的耐蚀性和耐冲刷腐蚀性能.结果表明,Ni-Cu-P合金镀层具有比Ni-P合金镀层更好的热稳定性、耐蚀性和耐冲刷腐蚀性能.     

GW93镁合金表面锡酸盐化学转化膜工艺研究

以锡酸钠为转化液主要成分对Mg-8.8Gd-3.1Y-0.6Zn-0.5Zr(GW93)镁合金进行无铬化学转化表面处理,通过全浸法评价转化膜在pH为中性的3.5%NaCl(质量分数)溶液中的腐蚀性能,利用光学显微镜、X射线衍射仪和扫描电子显微镜分析转化膜的微观形貌和相组成。结果表明,适用于GW93镁合金的锡酸盐转化膜的最佳工艺条件为:锡酸钠50 g/L,焦磷酸钠50 g/L,乙酸钠15 g/L,氢氧化钠5 g/L,柠檬酸3 g/L,碳酸钠20 g/L,转化温度80℃,转化时间15 min。转化膜主要组成为MgSnO3·3H2O。该工艺下形成的膜层为细小的、近球状颗粒堆积而成,表面均匀平整。腐蚀性能评价结果表明,未经锡酸盐化学转化的镁合金的平均腐蚀速率为6.1083 g·a-1·cm-2,经最佳化学转化成膜工艺处理后,该镁合金的平均腐蚀速率为0.1264 g·a-1·cm-2。抗腐蚀性能被提高了97.9%,说明该锡酸盐化学转化膜层可以有效地提高镁合金的耐腐蚀性能。     

AZ91D镁合金化学复合镀Ni-P-ZrO2的工艺与性能

对镁合金传统化学镀工艺进行了改进,避免了使用氢氟酸和六价铬等有毒物质。采用化学镀与化学复合镀相结合方法,在AZ91D镁合金上获得了Ni-P-ZrO2纳米化学复合镀层,并研究了新工艺化学镀前处理和镍沉积机理及复合镀层的结构和性能。结果表明:新工艺方法获得的Ni-P镀层更均匀、致密,耐蚀性优于传统工艺化学镀层;Ni-P-ZrO2复合镀层与AZ91D合金基体在3.5%NaCl溶液中的动电位极化曲线对比表明,该复合镀层对镁合金可以起到明显的保护作用;从磨损实验结果可见,Ni-P镀层的磨损质量损失率几乎为Ni-P-ZrO2镀层的3倍,说明ZrO2纳米粉的加入能改善镀层的耐磨性。     

Investigation of the corrosion for Mg-xGd-3Y-0.4Zr (x = 6, 8, 10, 12 wt%) alloys in a peak-aged condition

The corrosion behaviour of Mg-6Gd-3Y-0.4Zr (GW63K), Mg-8Gd-3Y-0.4Zr (GW83K), Mg-10Gd-3Y-0.4Zr (GW103K) and Mg-12Gd-3Y-0.4Zr (GW123K) were investigated in peak-aged condition using immersion and salt spraying tests and electrochemical measurements in 5% NaCl solution. The corrosion resistances of Mg-xGd-3Y-0.4Zr alloys were found to decrease with the increase of Gd content from 6% to 10% and then increase from 10% to 12%. The corrosion products of Mg-xGd-3Y-0.4Zr alloys were discovered to be composed of voluminous tiny erect flakes by FE-SEM, and the compactness of the corrosion films decreases with the increase of Gd content. The results of AES revealed that the corrosion film is enriched with Gd and Y. The potentiodynamic polarization curves showed that the overpotentials of cathodic hydrogen evolution on GW63K and GW83K are much higher than on GW103K and GW123K. The results of EIS are in good agreement with the morphologies of the corrosion products and the corrosion rates of the corrosion tests.     

Development of electroless (Ni-P)/BaNi0.4Ti0.4Fe11.2O19 nanocomposite powder for enhanced microwave absorption

Ni-, Ti-substituted nanocrystalline M-type barium hexaferrite powder (BaNi_xTi_xFe_12?2xO₁₉ (x = 0.4) of size ～10 nm) was coated with Ni-P by electroless (EL) coating technique to form EL Ni-P/BaNi_0.4Ti_0.4Fe_11.2O₁₉, a radar absorbing material (RAM) nanocomposite powder. Under TEM, the particle size of RAM powders before and after Ni-P coating were found to be in the range of 10–15 nm and 15–25 nm respectively. A uniform layer of 5–10 nm thick coating is deposited due to the controlled growth of EL Ni-P nanoglobules onto the powder. A growth mechanism was proposed to understand the deposition of EL Ni-P layer onto the RAM powder. The reflection loss (RL) of the EL (Ni-P)/RAM nanocomposite powder in Ku band (12.4 ?18 GHz) was evidently enhanced to ?28.70 dB, as compared to the EL Ni-P nanoglobules (?16.20 dB) and nanocrystalline RAM powder (?24.20 dB). After annealing at 400 °C for 4 h, the RL and bandwidth of EL (Ni-P)/RAM nanocomposite powder was further improved from ?24.20 to ?35.90 dB and 1.50 to 4.00 GHz respectively. The RL enhancement mechanism was explained on the basis of VSM study (hysteresis loops) and electromagnetic theory.     

锡酸盐转化前处理对镁合金化学镀镍镀层的影响

目的利用锡酸盐转化膜中间层避免化学镀镍镀层与金属基体的直接接触,降低其产生原电池腐蚀的趋势,提高镁合金化学镀镍层的耐蚀性及稳定性。方法采用锡酸盐化学转化膜技术在AZ31镁合金表面制备锡酸盐转化膜层,然后通过直接化学镀镍技术在该膜层上沉积Ni-P镀层。利用SEM、EDS、浸泡析氢、电化学测试等手段,研究了复合镀层的显微结构、相组成、耐蚀性。结果锡酸盐转化膜由细小均匀的球形颗粒堆积而成,颗粒之间存在空隙,为直接化学镀镍时镍磷的初始沉积提供了可能。化学转化膜表面沉积的化学镀镍层均匀致密,形成典型的胞状结构。基体-化学转化膜-化学镀Ni-P合金层三者之间的结合良好,保证了复合镀层优良的耐蚀性能。结论化学镀Ni-P层能够在不经过钯活化处理的条件下直接在锡酸盐转化膜上沉积,锡酸盐转化膜中间层避免了Ni-P阴极性镀层与阳极性镁基体的直接接触,降低了Ni-P镀层局部缺陷对整体防护效果的影响,提高了镀层的耐蚀性及耐久性。     

模拟海洋环境中Ni-Co合金镀层对AZ91D镁合金的腐蚀防护研究

目的提高AZ91D镁合金的腐蚀防护性能。方法采用化学镀前处理在AZ91D镁合金表面制备一种保护性的Ni-Co合金镀层。分别采用环境扫描电镜(ESEM)、X射线衍射(XRD)和能量散射谱(EDS)分析合金镀层的表面形貌、微结构特点和化学成分。采用动电位极化(PC)和电化学阻抗谱(EIS),分析测试在模拟海洋环境(中性3.5%Na Cl溶液)中Ni-Co合金镀层对AZ91D镁合金的腐蚀防护性能。结果镁合金表面化学镀Ni-P镀层均匀覆盖,晶粒生长较致密,表面呈菜花状形貌,Ni-P镀层中P质量分数约为5.6%。Ni-Co合金镀层表面均匀且呈金字塔状形貌,形成了面心固溶体(FCC),镀层中Co质量分数约为31%。Ni-P镀层和Ni-Co合金镀层的厚度分别约为11μm和19μm。在模拟海洋(中性3.5%Na Cl溶液)环境中,镁合金裸基体、化学镀前处理Ni-P镀层、Ni-Co合金镀层的腐蚀电位分别为-1485、-372、-284 m V,其腐蚀电流密度分别是3.4×10-5、1.8×10-6、2.9×10~(-7) A/cm2,所拟合的电荷转移电阻分别为4.72×103、1.70×104、2.06×106?/cm2。结论化学镀前处理Ni-P镀层可为镁合金提供较好的腐蚀防护,Ni-Co合金镀层能够为镁合金提供更显著的腐蚀防护。     

化学镀Ni-P合金耐蚀性能优化的研究方向

阐明了化学镀Ni-P合金具有许多优异的性能,其中最为突出的是耐蚀性能;综述了近年来化学镀Ni-P合金的耐蚀性的研究进展;分析了化学镀Ni-P合金的耐蚀性能;讨论了含磷量、热处理温度、前处理工艺等因素对镀层耐蚀性的影响;探讨了化学镀Ni-P合金的基本原理、反应机理和耐蚀机理;提出了通过优化工艺、添加稀土元素、采用多元合金化学镀等方法可提高化学镀Ni-P合金的耐蚀性能;并指出化学镀Ni-P合金的可能发展方向.     

热处理对压铸镁合金化学镀层组织和性能的影响

采用化学镀方法在AZ91D压铸镁合金表面获得N i-P镀层,研究了不同热处理温度对镀层的组织和性能的影响。结果表明:镍层中P含量为6.22 wt%,镀层组织为非晶+少量纳米晶组织。随热处理温度升高原始镀层中的非晶组织中先形成镍纳米晶,然后纳米晶镍伴随晶化过程进行迅速长大,并在镍基体上析出N i12P5和N i3P相。镀层与基体的结合强度在350℃附近达最大结合强度为3.7 MPa,镀层硬度在400℃附近达最大值为825 HV;盐雾腐蚀实验表明镀层耐腐蚀性能良好,连续盐雾8 h未出现腐蚀斑点。经过不同的热处理,镀层的耐蚀性随着热处理温度的提高而下降。     

热处理对砂型铸造Mg-10Gd-3Y-0．5Zr镁合金微观组织和力学性能的影响

采用金相分析、SEM、硬度试验和拉伸试验等方法分析和测试砂型铸造 Mg-10Gd-3Y-0.5Zr 镁合金在T6态（固溶后空冷然后时效）下的显微组织和室温力学性能,讨论该合金的断裂机理。结果表明,砂铸Mg-10Gd-3Y-0.5Zr合金在225℃和250℃时效下的最优T6热处理工艺分别为（525℃,12 h＋225℃,14 h）和（525℃,12 h＋250℃,12 h）。峰时效下T6态Mg-10Gd-3Y-0.5Zr合金主要由α-Mg＋γ＋β′相组成,2种峰时效热处理工艺下合金的抗拉强度、屈服强度和伸长率分别为339.9 MPa、251.6 MPa、1.5%及359.6 MPa、247.3 MPa、2.7%。在不同热处理工艺下Mg-10Gd-3Y-0.5Zr合金断裂的类型不同,峰时效态合金的断裂方式为穿晶准解理断裂。     

钨铜合金表面化学镀Ni-P镀层性能研究

从钨铜合金表面化学镀Ni-P镀层的表面形貌及成分,镀层结构,外观,结合力.硬度,耐磨性,孔隙率,纤焊性等方面进行了检测和表征.结果表明,化学镀Ni-P合金层磷含量为11.37%,属于高磷镀层,主要为非晶型结构,在钨铜合金表面化学镀Ni-P合金可以大大提高钨铜合金的硬度和耐磨性,且Ni-P合金镀层与钨铜合金基体结合强度好,孔隙率低,纤焊性好.