Influence of aluminum phosphate on the tribocorrosion performance of chemically bonded phosphate ceramic coatings

In this study, chemically bonded phosphate ceramic coatings (CBPCCs) with different contents of aluminum phosphate (AP) are prepared on stainless steel (AISI 304L). Differential scanning calorimetry, X-ray diffraction, contact angle test, and a tribocorrosion experiment are carried out to clarify the role of AP in the tribocorrosion performance of CBPCCs. The results show that, with the increase in the AP content, the enthalpy of curing increases because of the greater formation of the bonding phase AlPO₄. Both in static corrosion and in tribocorrosion, the corrosion current density of CBPCCs achieves the lowest value when the weight ratio of AP to polytetrafluoroethylene is about 0.78. Additionally, the influence mechanism of AP on tribocorrosion is clarified. AlPO₄ from the reaction between AP and Al₂O₃ has excellent mechanical properties and can enhance the wear resistance of CBPCCs by reducing the mechanical wear and the increased wear due to corrosion. The alumina particles wrapped by AlPO₄ can form a dense and smooth surface and change the direction of electrolyte propagation, which leads to the increase in the tribocorrosion resistance of CBPCCs.     

超音速火焰喷涂WC-10Co-4Cr涂层的摩擦腐蚀性能研究

目的研究不同喷涂距离下WC-10Co-4Cr涂层的摩擦腐蚀性能,探究其机理并优化工艺参数,以提高涂层性能。方法通过超音速火焰喷涂技术在304不锈钢基体上制备WC-10Co-4Cr防护涂层,通过扫描电子显微镜和X射线衍射仪研究涂层的微观结构及相组成,采用维氏显微硬度计测量涂层的显微硬度。采用装配有电化学工作站的摩擦磨损测试仪,对浸没于3.5%NaCl盐溶液中的涂层进行摩擦腐蚀实验,测量涂层在静态及滑动条件下的磨损率、摩擦系数和极化曲线。结果喷涂距离提高时,涂层孔隙率降低,硬度提高,达到1100～1400 HV。在腐蚀介质中滑动摩擦时,WC-10Co-4Cr涂层的磨损率较304不锈钢低2个数量级,磨损率为1.7×10~(-7)mm~3/(N·m),而304不锈钢的磨损率为2.6×10~(-5)mm~3/(N·m)。结论 WC-10Co-4Cr涂层良好的摩擦腐蚀性能归因于承受负载的WC相与产生钝化的金属粘结相之间的协同作用,其抵抗涂层受摩擦腐蚀破坏。     

外加电位对Monel400合金海水环境腐蚀磨损性能的影响

目的研究不同恒电位对Monel400合金海水环境腐蚀磨损性能的影响。方法将试样加工成圆柱试样,通过设计的特殊夹具夹紧试样,利用摩擦试验机和电化学工作站做不同恒电位下的磨蚀实验,通过开路电位极化曲线的变化评价合金的电化学性能,通过磨损量的变化评价合金的摩擦性能。通过扫描电镜揭示磨损机理,探讨交互作用机制。结果摩擦过程中的开路电位比静态腐蚀时的低。随着外加电位的增加,腐蚀电流密度增加,摩擦系数降低,总的体积损失量增加。腐蚀磨损存在明显的交互作用。结论摩擦能够破坏合金表面的钝化膜,导致具有更高电化学活性的新表面暴露于溶液中,因此促进了表面腐蚀。而腐蚀产生的腐蚀产物层比较粗糙和疏松,其剪切强度比基底合金低得多,因此当氧化铝块摩擦过合金表面时,很容易去除腐蚀产物层,进而促进了材料损失。腐蚀磨损条件下材料的损失量明显比纯磨损条件下的高。     

等离子喷涂Al2O3-13%TiO2涂层的海水腐蚀磨损性能

基于等离子喷涂技术构筑了高耐磨、耐蚀的Al2O313%TiO2涂层（AT13涂层）,利用Rtec磨蚀试验机研究AT13涂层在干摩擦、去离子水和人工海水介质中的摩擦磨损性能,并利用电化学工作站分析了涂层在静态腐蚀和滑动磨损中的开路电位和极化曲线的变化,探讨了AT13涂层的腐蚀磨损机理。结果表明：热喷涂AT13涂层由αAl2O3、γAl2O3、金红石型TiO2和Al2TiO5相组成,其中富Ti相呈条带状分布于富Al基体中;AT13涂层在海水工况具有较好的润滑性,与干摩擦相比,其摩擦因数减小了0.15,且具有较好的稳定性;在3种工况下,AT13涂层都具有优异的耐磨损性能,海水润滑条件下,AT13涂层具有最小的磨损率,且随载荷的增加而减小;磨损过程加重了海水对涂层的腐蚀,但影响较小。     

Corrosion and tribocorrosion study of 316L steel,Ti–6Al–4V and Ti–10Zr–10Nb–5Ta

ABSTRACT

In this paper, corrosion and tribocorrosion tests have been conducted on three biomaterials: Ti–6Al–4V and 316L steel that are well-known commercial biomaterials and Ti–10Zr–10Nb–5Ta, a new biomaterial elaborated in a levitation-melting furnace. Tests have been conducted in five different electrolytes: NaCl (9g/l), Ringer’s solution, phosphate buffered saline solution (PBS) with and without an addition of bovine serum albumin (BSA). Two amounts of BSA were used: 1 and 5?g/l. In NaCl solution, Ringer’s solution and PBS solution, Ti–10Zr–10Nb–5Ta presents the best corrosion resistance. Conversely, in the presence of proteins, 316L steel shows better resistance to corrosion in comparison with Ti–10Zr–10Nb–5Ta and Ti–6Al–4V. During tribocorrosion tests, the surfaces have been submitted to friction against an alumina ball at open circuit potential (OCP). Measurement of wear rate at the end of the tests indicates clearly that 316L steel shows better resistance to material removal in comparison with Ti–10Zr–10Nb–5Ta and Ti–6Al–4V.     

Assessing the tribocorrosion performance of Ti–6Al–4V, 316 stainless steel and Monel K500 alloys in artificial seawater

The electrochemical and tribocorrosion behaviors of Ti–6Al–4V, 316 stainless steel and Monel K500 alloys sliding against Al₂O₃ in artificial seawater are investigated in this paper. It can be observed that the open circuit potential drops down to more negative values due to the removal of passive film. And a rapid dissolution occurs in the wear track compared with the unworn area. The wear loss polarized in cathodic potential is lower than that in anodic potential and open circuit potential conditions, because the material deterioration is enhanced by corrosive attack. The wear volumes of 316 stainless steel are much higher than the ones measured for Ti–6Al–4V and Monel K500 alloys. Friction coefficients are significant large in cathodic polarization compared with anodic polarization for all alloys. Moreover, the 316 stainless steel exhibits large friction coefficients compared with Ti–6Al–4V and Monel K500 alloys.     

热丝激光熔覆17–4PH涂层组织与腐蚀磨损性能

目的 在低碳钢表面高效制备沉淀硬化马氏体不锈钢涂层,研究涂层在腐蚀磨损苛刻条件下耦合损伤行为。方法 采用热丝激光熔覆技术在20钢基材表面制备17–4PH马氏体不锈钢涂层,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)等分析涂层的相组成和显微组织,采用电化学腐蚀摩擦磨损试验仪对涂层的摩擦磨损、极化曲线、电化学阻抗谱(EIS)及腐蚀磨损耦合行为进行研究。结果 制备的涂层组织均匀、致密,无裂纹、气孔等缺陷,主要由马氏体相组成。熔覆区的平均硬度约为310HV0.1,约是基材硬度的1.5倍,自腐蚀电流密度为6.583×10^?8 A/cm²,具有优异的耐蚀性。在3.5%NaCl溶液中,随摩擦载荷的增加,涂层的开路电位下降,摩擦因数增大,自腐蚀电位下降,腐蚀电流密度增大,摩擦对腐蚀促进作用明显。结论 热材激光熔覆技术节能、高效,制备的17–4PH涂层结构致密、性能优异,可用于在腐蚀磨损苛刻环境下零部件的表面改性。     

锻造CoCrMo合金关节材料的滑动摩擦腐蚀行为

采用UMT-2多功能摩擦磨损试验机和电化学工作站(CHI614E)摩擦腐蚀试验平台,考察了医用CoCrMo合金在生理盐水润滑条件下的摩擦腐蚀行为,利用扫描电镜观察了CoCrMo合金在摩擦腐蚀之后的形貌特征。结果表明,随着载荷的增大,CoCrMo合金摩擦腐蚀后的腐蚀电位降低,腐蚀电流增大。摩擦腐蚀的摩擦因数均大于纯摩擦因数,且随载荷的增加而减小。摩擦腐蚀的磨损破坏比纯摩擦严重,磨损机理主要表现为犁沟磨损和剪切塑变造成的局部剥落。     

Improved Tribocorrosion Properties of Ti6Al4V Alloy by Anodic Plasma Electrolytic Oxidation

Ti6Al4V alloy has good corrosion resistance due to the formation of the passive oxide films on the surface of Ti6Al4V alloy. However, Ti6Al4V alloy has poor tribocorrosion resistance in the seawater environment. Herein the present work, plasma electrolytic oxidation (PEO) with the electrolyte of glycerol and sodium borate is used to generate PEO coatings on the surface of Ti6Al4V alloy to improve its tribocorrosion properties. The microstructure and tribocorrosion properties of PEO coatings are investigated by using scanning electron microscopy, X-ray diffraction, and tribometer, respectively. The growth kinetics and the tribocorrosion mechanisms of PEO coatings are discussed in detail. It is shown in the results that PEO coatings deposited on the surface of Ti6Al4V alloy are composed of rutile and anatase phases. The surface hardness and thickness of PEO coatings are enhanced with the increase of the voltage and time. The wear rate of Ti6Al4V alloy with PEO coatings is significantly reduced in artificial seawater.