化学镀Ni—P复合耐磨镀层的研究进展

化学镀Ni—P镀层具有良好的耐蚀性,但耐磨性不佳,通过引入纳米或微米粒子可以提高其耐磨性。本文综述了近几年来国内外在颗粒增强复合镀层、稀土增强复合镀层和减摩复合镀层方面的研究进展,并指出了Ni—P复合耐磨镀层在基础研究中的主要发展方向。     

提高镀铬层性能的方法

简要分析了镀铬层的结构 ,并对提高铬镀层的亮度、耐蚀性、硬度和耐磨性等性能的方法进行了研讨     

热处理对Ni-P基镀层耐高温腐蚀磨损性的影响

Ni-P化学镀层经过热处理后，镀层硬度、耐蚀性、耐磨性得到提高。在Ni-P化学镀的基础上，加入元素Co和SiC微粒，形成Ni-Co-P/SiC复合镀层，经过100～600℃回火后，与Ni-P镀层相比，复合镀层表现出高硬度、高温耐磨性变化趋势小的特点，尤其经过300℃回火后，复合镀层表现出最佳的耐高温腐蚀磨损性。     

提高镀铬层性能的方法

简要分析了镀铬层的结构，并对提高铬镀层的亮度、耐蚀性、硬度和耐磨性等性能的方法进行了研讨。     

热处理对Fe—Cr—Ni合金镀层结构性能的影响

通过对Ｆｅ－Ｃｒ－Ｎｉ合金电刷镀层的结构、结合力、硬度和耐蚀性的测试，探讨了热处理对该合金镀层结构性能的影响，试验结果表明，经１０５０℃固溶处理可使镀层结构由镀态的微晶体＋非晶态结构转变为ｒ单相结构，使镀层的结合力和耐蚀性都有提高。镀层的硬度随热处理温度的升高呈山形变化。温度为４００℃时，硬度由镀态时的ＨＶ４５０增至ＨＶ９４０，故有利于提高镀层的耐磨性。     

热处理对Fe－Cr－Ni合金镀层结构性能的影响

通过对Ｆｅ－Ｃｒ－Ｎｉ合金电刷镀层的结构、结合力、硬度和耐蚀性的测试，探讨了热处理对该合金镀层结构性能的影响．试验结果表明，经１０５０℃固溶处理可使镀层结构由镀态的微晶体＋非晶态结构转变为γ单相结构，使镀层的结合力和耐蚀性都有提高．镀层的硬度随热处理温度的升高呈山形变化，温度为４００℃时，硬度由镀态时的ＨＶ４５０增至ＨＶ９４０（最大值），故有利于提高镀层的耐磨性．     

Ni-ZrO_2纳米复合镀层研究进展

综述了Ni-ZrO2纳米复合镀层的研究现状,重点阐述镀层的沉积机理.从镀层的组织结构出发,探讨其特殊的硬度、耐磨性、抗疲劳性、抗高温氧化性及耐蚀性,以及影响镀层沉积的主要工艺参数,分析了Ni-ZrO2纳米梯度复合镀层.分析认为,Ni-ZrO2纳米复合镀层的研究尚存在较大的发展空间,应进一步优化镀层的综合性能,拓展其在工程领域中的应用.     

Ni-P合金化学镀层的组织结构及性能

利用X-射线衍射及扫描电子显微分析等技术对Ni-P合金镀层的组织结构进行了研究．结果表明,含P量为12％的Ni-P合金镀层在镀态下呈非晶态结构,经300℃以上温度时效处理后,则成为由Ni基固溶体和Ni3P两相组成的晶态结构．镀层性能测试结果表明,镀层的硬度、耐磨性及耐蚀性与时效处理温度密切相关：经400℃时效处理后镀层硬度最高,随时效温度的升高耐磨性能提高,而在HCl介质中的耐蚀性则基本呈降低趋势．     

探索硬质阳极化前后高精度尺寸的控制

在航空领域中,要求很多产品零件的表面具有高耐磨性及耐蚀性,这通常采用硬质阳极化处理来实现。零件表面镀层厚度会影响高精度尺寸的大小,为此控制高精度尺寸的镀前尺寸和镀层厚度是镀后尺寸合格的重要保证。     

热处理对电刷镀镍-磷镀层性能的影响

电刷镀非常适合于大型模具的现场修理,在常用刷镀层中,镍层、镍钨钴合金及某些复合刷镀层一般难以满足大型模具的综合性能要求,而镍磷镀层是一种通过热处理可以改善其性能的镀层.作者通过研究热处理对不同磷含量的镍-磷镀层硬度、耐磨性、耐蚀性及结合强度的影响规律发现,含磷2%左右的镍磷镀层通过400℃左右的热处理后具有最佳的硬度、耐磨性和结合强度,而含磷10%左右的镍磷镀层经600℃左右的热处理后具有最佳的耐蚀性能,这可以为电刷镀在大型模具的修理方面针对不同的使用要求提供合适的镀层和热处理方法.     

复层牺牲用极的研制及其抗蚀特性

本文研制了一种新型的复层牺牲阳极,其构成是钢表面氮碳共渗形成的ε相层为内层覆以电位较低的化学镀Ni-P合金为外层。金相和SEM电镜分析表明,ε-相层表面经过合适的活化后的化学镀Ni-P合金层不仅结构致密,而且二者界面呈牢固的锯齿状结合。标准盐雾和醋酸浸泡试验证明,由于这种复层充分发挥了二者硬度高,耐蚀抗磨性能好的特点,同时避免了ε相层表面疏松、Ni-P化学镀层存在针孔的缺点,因此其抗蚀性十倍甚至百倍的优于单一的ε相层或Ni-P化学镀层。     

Effect of Salt Spray Corrosion on Tribological Properties of HVOF Sprayed NiCr-Cr_3C_2 Coating with Intermediate Layer

The objective of the present work was to determine the influence of the neutral salt spray corrosion on the wear resistance of HVOF sprayed NiCr-Cr_3C_2 coating with intermediate layer. Ni-Zn-Al_2O_3 coatings as interlayers were prepared by low pressure cold spray(LPCS) between NiCr-Cr_3C_2 cermet coatings to form a sandwich structure to enhance the corrosion resistance properties. The tribological properties were examined using the UMT-3 fricition and wear tester by line-contact reciprocating sliding under dry and salt spray one week corrosion. The morphology, element distribution, and phase compositions of the coating and worn sufaces were analyzed by using scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction respectively. The corrosion behavior of the coating was studied by the open-circuit potential, the electrochemical impedance spectroscopy, potentiodynamic polarization, and salt spray corrosion methods. It is found that the sandwich structured coating has better corrosion resistance than the single layer coating. The results show that under dry wear conditions, the wear mechanism is abrasive and adhesive wear, whereas under salt spray corrosion conditions it becomes corrosion wear. The friction coefficient of the sandwich structured coating after salt spray corrosion is slightly lower than the dry friction coefficient, but the weight of the wear loss is lower than that under dry condition.     

Effect of salt spray corrosion on tribological properties of HVOF sprayed NiCr-Cr<Subscript>3</Subscript>C<Subscript>2</Subscript> coating with intermediate layer

The objective of the present work was to determine the influence of the neutral salt spray corrosion on the wear resistance of HVOF sprayed NiCr-Cr₃C₂ coating with intermediate layer. Ni-Zn-Al₂O₃ coatings as interlayers were prepared by low pressure cold spray (LPCS) between NiCr-Cr₃C₂ cermet coatings to form a sandwich structure to enhance the corrosion resistance properties. The tribological properties were examined using the UMT-3 fricition and wear tester by line-contact reciprocating sliding under dry and salt spray one week corrosion. The morphology, element distribution, and phase compositions of the coating and worn sufaces were analyzed by using scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction respectively. The corrosion behavior of the coating was studied by the open-circuit potential, the electrochemical impedance spectroscopy, potentiodynamic polarization, and salt spray corrosion methods. It is found that the sandwich structured coating has better corrosion resistance than the single layer coating. The results show that under dry wear conditions, the wear mechanism is abrasive and adhesive wear, whereas under salt spray corrosion conditions it becomes corrosion wear. The friction coefficient of the sandwich structured coating after salt spray corrosion is slightly lower than the dry friction coefficient, but the weight of the wear loss is lower than that under dry condition.     

AZ91D镁合金表面等离子喷涂Al_2O_3-TiO_2陶瓷涂层的微观组织及防护性能

采用大气等离子喷涂技术在AZ91D镁合金表面制备Al2O3-TiO2陶瓷涂层。对涂层的显微组织、化学成分、相组成及显微硬度进行表征,并对涂层的耐磨损和耐电化学腐蚀防护性能进行研究。结果表明,Al2O3-TiO2陶瓷涂层的组织呈现层状结构,主要组成相为α-Al2O3、γ-Al2O3和金红石TiO2。涂层平均硬度654.2HV,涂层具有良好的抗磨损和抗电化学腐蚀防护性能。     

熔融锌对沉没辊腐蚀磨损过程的影响

为了研究材料或涂层在熔融锌中的耐腐蚀磨损情况,自行研制了一种耐熔融锌腐蚀磨损试验机,并介绍了该试验机的工作原理和结构组成.利用该腐蚀磨损试验机,对Al_2O_3涂层在锌液中的腐蚀磨损性能进行了测试,利用扫描电子显微镜与能谱仪对比分析了未经腐蚀磨损试件、腐蚀磨损5 d试件、腐蚀磨损10 d试件的组织和成分变化,并对Al_2O_3涂层的失效机制进行了分析.结果表明,该腐蚀磨损试验机可以模拟热镀锌沉没辊在熔融锌液中的工作状况,从而可以对沉没辊的失效情况进行更直观的分析,因而可为耐熔融锌腐蚀磨损材料或涂层的研究提供理想平台.     

High temperature behaviors of high velocity arc sprayed Fe-Al/Cr3C2 composite coatings

Fe-Al/Cr3C2 composite coatings were manufactured using high velocity arc spraying （HVAS） technology. The high temperature erosion, wear and corrosion resistance of the coatings were investigated. The coating properties such as bonding strength, porosity, hardness as well as microstructures were characterized. The results show that the coatings have relatively high heat tremble bond strength, hardness, and typical layer-shaped coatings＇ microstructures. With the rise of temperature, the coating erosion resistance increases too; the impingement angel does effects on erosion properties, and the erosion mechanism changes from ductile to brittle behaviors at 450℃. The coatings have good room temperature wear resistance and relatively good high temperature resistance. The wear mechanism of the coatings is peeling wear behavior. The coatings have excellent high temperature corrosion resistance because of the produce of oxides during corrosion.     

高能脉冲类激光熔覆镍基合金层的组织及性能

为了提高304不锈钢表面的综合性能,采用高能脉冲类激光熔覆沉积技术在304不锈钢表面制备了镍基合金熔覆层.采用扫描电子显微镜、能谱仪、X射线衍射仪、销-盘磨损试验机与电化学测试系统对镍基合金熔覆层的显微组织、相结构、耐磨损性能和电化学腐蚀性能进行了研究.结果表明,镍基合金熔覆层与304不锈钢基材呈良好的冶金结合,熔覆层的相对耐磨损性为304不锈钢基材的4.4倍.熔覆层组织由γ-Ni基体相、Ni_3Mo、Fe_7Mo_3和Cr_(23)C_6碟状增强相与不规则棒状增强相组成.增强相是提高耐磨损性能的主要原因,增强相与基体相的电极电位差是导致腐蚀电流密度增加的主要原因.     

氢氟酸浓度对Ni-Cu-P镀层耐蚀性的影响

利用金相显微镜观察了Ni-Cu-P化学镀层的表面形貌,采用浸泡法与电化学阻抗谱测试了Ni-Cu-P镀层在不同浓度氢氟酸溶液中的耐蚀性.结果表明,Ni-Cu-P镀层均匀、致密,在氢氟酸介质中表现出良好的耐蚀性能,且随着氢氟酸溶液浓度的增大,镀层的腐蚀速率呈先升高后降低的趋势.     

电解液对镁合金微弧氧化层耐蚀性的影响

为了提高镁合金基体的耐蚀性,采用微弧氧化法在镁合金表面制备了MgO-ZrO2复合陶瓷层,利用XRD和SEM研究了膜层的相组成、结构及生长过程,并用LK98C电化学综合系统测试了其耐蚀性.实验结果表明：三种电解液中,K2ZrF6-KOH耐蚀性能较好;在交流阻抗测试结果中,镁基体出现了点蚀;K2ZrF6为8g/L,KOH为3.2g/L时,电荷转移电阻较高,达到4.058×105Ω.     

热喷涂铝涂层在矿井水中的耐蚀性能研究

应用腐蚀失重方法和电化学极化技术研究了热喷涂铝涂层在矿井水环境下的耐腐蚀性能,并与普通碳钢Ｑ２３５进行对比．实验结果表明,在一般中性矿井水中,涂层的自腐蚀电位附近的腐蚀受阴极氧扩散控制,当电位较高时,阳极上有氢析出,阳极反应由此变得复杂;用阴极极化能更好地显示涂层的电化学极化过程．热喷涂铝层具有较高的耐蚀性,实验涂层的预计使用寿命为２０ａ．比较了用失重法和电化学法计算涂层腐蚀速度的结果;分析了在２０～６０℃范围内温度对涂层腐蚀过程的影响