电沉积镍合金的冲蚀-腐蚀磨损研究

采用MSH型腐蚀磨损试验机研究了电沉积纯Ni、Ni-P非晶合金、Ni-W-P非晶合金的冲蚀-腐蚀磨损行为,并结合电化学测量系统研究了上述材料冲蚀与腐蚀之间相互促进机理。结合XRD分析了冲蚀前后电沉积镍合金的相变行为。结果表明：冲蚀-腐蚀磨损试验前后,电沉积镍合金镀层的硬度都增加;Ni-P非晶合金受到冲击后,镀层明显的发生了由非晶向微晶的转变;镍合金在含盐砂浆中的腐蚀性能随着工况的不同而不同,试样在含盐砂浆中的冲击速度由0增加到3.14ms-1时,三种材料的腐蚀速率都减小,之后随着冲击速度的增大,试样腐蚀速度增加;镍及镍合金材料的冲蚀-腐蚀磨损失重都以冲蚀失重为主,试验条件下冲蚀与腐蚀的交互作用最高能使材料的冲蚀-腐蚀磨损失重增加42%。     

输电塔既有涂层与新涂层受风沙侵蚀的损伤机理

对输电铁塔杆件新镀锌涂层和既有镀锌涂层进行风沙冲蚀磨损试验,对比分析了两种不同镀锌涂层的冲蚀损伤规律。采用扫描电子显微镜和激光共聚焦显微镜观测两种涂层的不同冲蚀磨损微观形貌,分析了两种涂层材料受风沙冲蚀的损伤机理。研究表明:冲蚀速度越高,两种涂层的冲蚀率越大,且既有涂层的冲蚀率在相同的冲蚀条件下比新镀锌涂层的冲蚀率要高500×10~(-5)～2 750×10~(-5)mg/g;两种涂层在冲蚀角度α为35～37°时出现了最大冲蚀率,分别为2.5×10~(-5)mg/g(新涂层)和0.014 mg/g(既有涂层)。两种涂层在冲蚀角度α=90°时冲蚀率最小,分别为0.5×10~(-5)mg/g(新涂层)和700×10~(-5)mg/g(既有涂层);两种涂层的冲蚀形貌是从低角度的犁沟型冲蚀沟发展到冲蚀沟和冲蚀坑并存,再到高角度仅存的冲蚀坑形貌。风沙流对输电铁塔杆件新镀锌涂层和既有镀锌涂层的冲蚀磨损过程大致相同,既有镀锌涂层的冲蚀坑和带状冲蚀沟比新镀锌涂层更深、更长,且表面更加粗糙。     

挟沙风作用下风力机叶片涂层冲蚀特性研究

内蒙古中西部地区高频出现沙尘暴活动,风力机叶片涂层长期被挟沙风冲蚀磨损,导致风力机叶片涂层出现冲蚀坑和裂纹,缩短风力机叶片寿命。针对这一问题,利用自制的挟沙风试验台,采用气流挟沙喷射法对以环氧玻璃纤维板为基底的风力机叶片涂层进行低角度加速冲蚀磨损试验,用失重测量法测定冲蚀磨损量与冲蚀速度的关系,用扫描电镜(SEM)观测分析涂层表面的冲蚀形貌来确定冲蚀机理,并提出涂层冲蚀磨损程度的评价计算公式。结果表明:涂层的冲蚀磨损量随着冲蚀速度的增大而增加;低角度冲蚀以微切削冲蚀磨损作用为主,材料的硬度起着决定性作用,高角度冲蚀主要以挤压变形冲蚀磨损为主,材料的韧性起决定性因素,由于聚氨酯涂层材料是塑性材料,其韧性高而硬度低,故在低冲蚀角下冲蚀磨损量大;验证了评价计算公式用于评价涂层冲蚀磨损程度的可靠性,为运行在风沙环境下的风力机叶片涂层的改进提供理论依据。     

硅酸盐封孔剂对热喷涂304不锈钢涂层高温冲蚀磨损性能的影响

采用热喷涂工艺制备的涂层常存在不少孔隙。为了弥补孔隙带来的抗腐蚀、冲蚀性能下降等问题,采用高速电弧在Q235钢基体上热喷涂304不锈钢涂层,采用封孔剂来处理热喷涂工艺带来的涂层孔隙,用碱金属硅酸盐基料、云母粉和SiO₂纳米颗粒为填料制备封孔剂,并用刷涂法对涂层进行封孔处理,研究了封孔层和喷涂层的抗高温冲蚀磨损性能。采用扫描电镜（SEM）和能谱仪（EDS）分别对喷涂层、封孔层的微观形貌和成分进行分析,研究喷涂层、封孔层在25,650℃温度下的冲蚀磨损性能和机理,并利用试验冲蚀磨损量估算了封孔层、喷涂层的冲蚀磨损寿命。结果显示：封孔层未见内部裂纹,与喷涂层结合紧密,但内部存在较多孔洞。封孔层在低攻角下的冲蚀磨损性能要好于未封孔的喷涂层。随着冲蚀温度由25℃升高至650℃,封孔层的冲蚀磨损量提高约20%,降低了封孔层的冲蚀磨损性能。封孔层、喷涂层的冲蚀磨损机理为低攻角下的犁沟、切削共同作用,以及高攻角下的挤压破坏。在冲蚀低攻角下,封孔层相比喷涂层具有更好的抗冲蚀磨损性能,在一定程度上封孔层能有效增强喷涂层的抗冲蚀磨损性能。     

水力机械胶粘耐磨涂层的制备及性能研究

为了提高在腐蚀与磨损环境下金属机械设备的使用寿命,采用胶粘涂层法制备了具有耐冲蚀磨损性能的水力机械胶粘耐磨涂层.富锌环氧底层和环氧云铁中间涂层均能有效地防止氧、水和盐等腐蚀介质对金属基体的侵蚀,改性的环氧耐磨表面层则具有优异的耐冲蚀磨损性能.采用自制砂流冲蚀试验机对涂层的耐磨损性能进行测试,结果表明,涂层的磨损率平均值为0.012%,具有比同类产品更好的耐冲蚀磨损性能;底部涂层与基体间相互吸附、涂层间相互扩散、基材表面与底部涂层机械互锁,均能使涂层与涂层之间、底层与基体之间在界面处形成牢固的结合,有利于提高涂层的抗冲蚀磨损性能.     

添加纳米TiC对NiTi／Cr3C2高速电弧喷涂涂层组织及耐高温冲蚀磨损性能的影响

本文探讨了加入纳米TiC对高速电弧喷涂NiTi／Cr3C2涂层组织和性能的影响,并对该涂层进行了高温冲蚀磨损试验。通过力学性能测试、EDS和XRD分析、光学金相显微镜以及SEM形貌观测表明,含纳米TiC的NT-1涂层基体中有大量弥散相,高温冲蚀规律为半塑性磨损冲蚀特点,无论在低冲蚀角还是高冲蚀角条件下,其耐高温冲蚀性能均优于不含纳米TiC的NT-2涂层。     

WC?12Co等离子喷涂层的冲蚀磨损数值模拟

西部强风沙尘环境下金属材料表面等离子喷涂层由于受到颗粒的撞击作用,造成涂层冲蚀磨损。以等离子喷涂WC?12Co涂层为对象,研究不同影响因素下涂层的冲蚀磨损速率和冲蚀效果;运用ANASYS?FLUENT软件中标准k?ε模型和离散相模型(DPM),通过改变风速、颗粒直径、颗粒质量流量对涂层冲蚀过程进行数值模拟,/s时,涂层冲蚀磨损速率最大为2.232×10-4k研g/究(m了2其·s冲);蚀颗磨粒损直径的为分0布.5 5情m况m。时结,涂果层表冲明蚀:磨风损速速为率1最5.大68为m1.824×10-4kg/(m2·s)。模拟结果验证了试验所     

运行状态下风力机叶片涂层沙蚀磨损研究

通过对运行状态下的1.5 MW风力机叶片缩微模型进行冲蚀磨损试验,模拟真实运行状态下风力机叶片涂层的冲蚀磨损过程,研究不同叶轮转速、叶片分区、沙粒粒径对叶片涂层冲蚀磨损量的影响,分析叶尖前缘和近后缘处表面磨损的微观形貌,明确了运行状态下风力机叶片与沙粒之间的相互作用方式及冲蚀磨损机理.运行状态下,风力机叶片涂层冲蚀磨损进程特征依次为麻面、冲蚀坑、冲蚀坑合并、涂层小块剥落和涂层大面积剥落.不同叶轮转速下叶片涂层的冲蚀磨损量虽存在差异,但冲蚀磨损进程有着较高的相似性,可将整个过程分为磨损孕育期、快速磨损期和缓慢磨损期.随着冲蚀区域与叶根距离的增大,叶片涂层的冲蚀磨损量不断增大.不同粒径沙粒冲击叶片涂层,冲蚀磨损进程总体趋势相似,但粒径越小,冲蚀磨损进程的发展越缓慢.沙粒冲蚀前缘处的相对运动可近似为垂直冲击,冲蚀磨损特征主要为近圆形冲蚀坑及横向裂纹扩展下的涂层脱落;冲击近后缘处时,冲蚀磨损程度明显低于前缘处,冲蚀磨损形式主要为凹形压痕及鳞片状薄片脱落.     

粘结相含量对超音速火焰喷涂Cr_3C_2-NiCr涂层冲蚀磨损的影响

采用不同粘结相含量的粉末,运用超音速火焰喷涂方法制备了Cr3C2-NiCr涂层。运用干砂冲蚀磨损试验机检测不同冲蚀角度下涂层的冲蚀磨损性能,研究粉末粘结剂含量对沉积涂层冲蚀磨损性能的影响。运用扫描电镜技术观察并分析Cr3C2-NiCr涂层冲蚀磨损失效行为。结果表明:粘结相含量不同的HVOF喷涂涂层均表现出脆性材料的冲蚀磨损特性,随冲蚀次数的增加失重量呈近似线性增加;粘结相在涂层中的分布形式影响涂层的抗冲蚀性能,但不改变冲蚀失效的主要机制。     

电沉积Ni-P非晶合金的冲蚀-腐蚀磨损行为

采用MSH型腐蚀磨损实验机,通过改变水砂两相流的冲击速度、含砂量和固相粒径等环境因素,研究了电沉积Ni-P非晶合金的冲蚀-腐蚀磨损行为。结果表明,电沉积Ni-P非晶合金的冲蚀失重率和冲蚀-腐蚀失重率均随着冲击速度、含砂量和固相粒径的增加而增大。与AISI 304不锈钢相比,电沉积Ni-P非晶合金冲蚀失重率和总失重率较高,但腐蚀失重率较低,也表现出了良好的抗冲蚀-腐蚀磨损性能。棒状Ni-P非晶合金镀层的冲蚀-腐蚀磨损,正面以砂粒挤压锻打造成的唇片和断裂为主,侧面以切削和犁削为主。     

等离子喷涂Cr_3C_2-NiCr及其表面化学镀Ni涂层的摩擦学特性

考察了等离子喷涂Ｃｒ３Ｃ２－ＮｉＣｒ涂层及其表面化学镀Ｎｉ镀层通过不同配副组成摩擦副的摩擦学特性,并应用ＳＥＭ、ＸＲＤ和ＸＰＳ对磨痕进行了分析．结果发现：等离子喷涂Ｃｒ３Ｃ２－ＮｉＣｒ涂层及其表面化学镀Ｎｉ镀层自配副组成摩擦副,均表现出较大的摩擦系数和磨损系数;但是,Ｃｒ３Ｃ２－ＮｉＣｒ涂层表面化学镀Ｎｉ镀层与Ｃｒ３Ｃ２－ＮｉＣｒ涂层配副组成摩擦副,在于摩擦条件下,能达到０．１２的摩擦系数和接近１０－６ｍｍ３（Ｎｍ）－１的磨损系数．上述结果是由于Ｃｒ３Ｃ２－ＮｉＣｒ涂层的磨损机理从强烈的层状颗粒剥落转变为沿气孔和微裂纹等处的颗粒断裂．     

Thermisches Spritzen vanadiumkarbidverstärkter Eisenbasisschichten

Thermal spraying of vanadium carbide reinforced iron based HVOF sprayed cermet coatings for wear protection like WC‐Co(Cr) and Cr₃C₂‐NiCr have found a broad range of applications in the past. By using chromium containing matrices, they exhibit good corrosion resistance along with outstanding wear resistance. In present research in the area of powder metallurgy and PTA welding iron based alloys with high content of chromium and vanadium have been developed, revealing similar properties and therefore being a cost efficient alternative to established cermet coatings. HVOF sprayed coatings of these iron based alloys are investigated regarding their economic applicability and their corrosion and wear properties.     

Effect of WC Particle Size on the Abrasive Wear of Thermally Sprayed WC-Co Coatings

Four types of WC-Co powders with different WC particle sizes are sprayed to produce WC-Co coatings with a Jet-Kote gun using a gas mixture of C₂H₂-30% C₃H₆ and pure propylene as fuel gases. The carbide size in sprayed high velocity oxy-fuel (HVOF) WC-Co coatings is measured from the microstructure. The abrasive wear of the coatings is characterized using a Suga abrasive wear tester. The abrasive wear mechanism of thermally sprayed WC-Co is discussed. The relationship between the relative wear of WC-Co coatings and carbide sizes is established according to the strength theory on hard alloy. The correlation with experimental data proves that the relative abrasive wear of WC-Co coating is proportional to square root of relative carbide size.     

超音速火焰喷涂Cr3C2-NiCr涂层磨粒磨损性能的研究

采用橡胶轮磨损试验机，对三种类型粉末制备的超音速火焰喷涂Cr3C2-25%NiCr涂层的磨粒磨损性能进行了试验，研究了喷涂工艺条件和粉末制备工艺对涂层磨损失重量的影响。在运用扫描电镜对涂层磨损表面观察分析的基础上，探讨了该涂层的磨粒磨损失效机制。     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

On the role of particle state and deposition procedure on mechanical,tribological and dielectric response of high velocity oxy-fuel sprayed alumina coatings

It is well known that the high velocity oxy-fuel based thermal spray process impart high density and reduced porosity in coatings compared to those produced by other ambient thermal spray processes. The benefits of HVOF have largely remained in the domain of metals and cermets and limited investigations have been carried out in ceramic coatings. The ability to produce high density ceramic coatings (e.g. alumina) offers potential in high performance applications in the field of wear, corrosion resistance and dielectric coatings. However, due to extreme operational limits of the HVOF process, the fundamentals of process–structure–property relationships are not fully understood.In this paper, we report an integrated approach to establish processing–microstructure–property correlations in order to optimize coatings for such applications. This approach involves diagnostic studies, microstructure development and its resultant influence on properties of high velocity oxy-fuel (HVOF) sprayed alumina coatings. The diagnostic studies were aimed to investigate the effects of fuel gas/oxygen ratio and amount of total gas flow on the particle temperature and velocity. Furthermore, splats and coatings were deposited to investigate the relationship between diagnostic data, melting behavior and droplet substrate interactions. Such a comprehensive study, coupled with property measurements of the coatings, demonstrates critical operational variables among deposition procedure, coating microstructure and the deposit properties.     

等离子喷涂Cr3C2-NiCr及其表面化学镀Ni涂层的摩擦学特性

考察了等离子喷涂Ｃr3C2-NiCr及其表面化学镀Ni涂层通过不同配副组成摩擦副的摩擦学特性,并应用ＳＥＭ、ＸＲＤ和ＸＰＳ对磨痕进行了分析,结果发现,等离子喷涂Ｃr3C2-NiCr涂层及其表面化学镀Ni镀层自配副组成摩擦副,均表现出较大的摩擦系数和磨损系数,但是,Ｃr3C2-NiCr涂层表面化学镀Ｎi镀层与Ｃr3C2-NiCr涂层配副组成摩擦副,在干摩擦条件下,能达到０．１２的摩擦系数和接近１０^6mm^3(Nm)^-1的磨损系数,上述结果是由于Ｃr3C2-NiCr涂层的磨损机理从强烈的层状颗粒剥落转变为沿气孔和微裂纹等处的颗粒断裂。     

超音速火焰喷涂微米碳化物涂层的组织与性能

WC-Co,NiCr-Cr3C2喷涂层耐冲蚀、耐磨性优良,但耐盐酸腐蚀报道较少.为此,采用超音速火焰喷涂(HVOF)工艺制备了WC-Co和Cr3C2-NiCr涂层,测定了涂层的孔隙率和结合强度,用XRD分析了涂层腐蚀前后的相结构及在1 mol/L HCl溶液中浸泡涂层材料的失重情况,分析了涂层的均匀腐蚀机理.结果表明:WC-Co和Cr3C2-NiCr涂层组织较为致密,孔隙率分别为2.67%,4.39%,结合强度分别为49.576,41.023 MPa.Cr3Cr2-NiCr涂层中相结构复杂,涂层中Cr3C2少量分解且含有非晶相;经1 mol/L HCl溶液浸泡后WC-Co涂层和Cr3C2-NiCr涂层失重较少.涂层的腐蚀机理为选择性腐蚀.缺陷越少涂层的耐蚀性越好,减少涂层中的孔隙、显微裂纹和夹杂等缺陷是提高涂层耐蚀性的关键.     

Surface Refinement of Metal Foams

Aluminium foams produced via the PM‐process are characterized by a moderate specific strength, a high surface roughness, and a poor wear behavior; to increase their mechanical properties and to improve the surface finish, wear and corrosion resistance; thermally sprayed coatings can be applied. The quality of the coating depends on the coating material, the chosen process, the preparation of the surface and spraying parameters. Aluminium alloys and iron based alloys for abrasive applications were deposited via electric arc spraying, ceramic coatings against wear were deposited by means of plasma spraying. Hard metallic coatings for severe abrasive applications were applied by high‐velocity‐oxyfuel spraying (HVOF). The results proved the suitability of this technique to significantly enhance the mechanical properties and the surface finish of metal foams. The specific strength and stiffness of the new composite materials outperform pure metal foams. The corrosion behavior was tested performing a salt spray test.     

Influence of CO2 laser heat treatment on surface properties,electrochemical and tribological performance of HVOF sprayed WC–24%Cr3C2–6%Ni coating

In this investigation, the tribological and electrochemical performances of HVOF sprayed WC–24%Cr₃C₂–6%Ni coatings before and after laser heat (LH) treatment were investigated. In the wear test, the friction and wear resistance of the coatings were improved significantly with an optimized LH process. The improvement can be attributed to the improved roughness and hardness, as well as the formation of oxide tribofilms. With LH treatment, the local corrosion of the coating had a decrease and the pit corrosion resistance of the WC–24%Cr₃C₂–6%Ni coating was improved as a result of the decreasing the size and number of the porosities, especially compact interface achieved by LH treatment.