船用辅汽轮机转子汽封轴颈喷涂WC-12Co涂层的摩擦学性能研究

采用超音速火焰喷涂技术和电镀技术分别在45钢试件表面制备了WC-12Co涂层和硬铬镀层,测试了涂层/镀层显微硬度和室温摩擦磨损性能,并观察分析了磨损表面形貌。结果表明：WC-12Co涂层的显微硬度是电镀硬铬层的1.5倍以上,表明WC-12Co涂层的抗疲劳强度性能更优;在时间为1.5h,载荷为20N和100N的试验条件下,电镀硬铬层摩擦磨损失重量分别为WC-12Co涂层的3倍和4倍,表明WC-12Co涂层的耐磨性能明显优于电镀硬铬镀层;与硬铬镀层相比,WC-12Co涂层能缩短磨合时间,较快地进入稳定磨损阶段,该阶段因WC-12Co涂层摩擦因数低,波动范围小,更有利于摩擦状态下延长工件的使用寿命。将超音速火焰喷涂技术用于修复汽轮机转子汽封轴颈,可极大提高汽轮机转子的技战术性能,降低维修频率,延长使用寿命。     

河北钢铁唐钢研发成功碳化钨涂层辊

历时半年时间,由河北钢铁集团唐钢机械（重机）装备公司承担的为唐钢高强度汽车板生产线提供的碳化钨（WC）涂层辊,经西门子公司验收,完全达到使用标准。碳化钨（WC）涂层辊研发成功标志着该单位已经掌握尖端的热喷涂技术。该技术是采用先进的超音速喷涂（HOVF）手段制作碳化钨（WC）涂层辊备件,替代传统的电镀硬铬辊。与电镀硬铬相比,新工艺具有更加优异的耐磨损、耐腐蚀、防打滑、抗黏铁、抗黏锌性能,使用寿命较电镀硬铬辊提高1.5倍以上。     

船用辅汽轮机转子汽封轴颈喷涂WC–12Co涂层的摩擦学性能

采用超音速火焰喷涂技术和电镀技术分别在45钢试件表面制备了WC-12Co涂层和硬铬镀层,测试了涂层、镀层的显微硬度和室温摩擦磨损性能,并观察分析了磨损表面形貌。结果表明:WC-12Co涂层的显微硬度是电镀硬铬层的1.5倍以上;在时间为1.5h,载荷为20N和100N的试验条件下,电镀硬铬层摩擦磨损失质量分别为WC-12Co涂层的3倍和4倍,表明WC-12Co涂层的耐磨性能明显优于电镀硬铬镀层;与硬铬镀层相比,WC-12Co涂层能缩短磨合时间,较快地进入稳定磨损阶段,该阶段因WC-12Co涂层摩擦因数低,波动范围小,更有利于摩擦状态下延长工件的使用寿命。将超音速火焰喷涂技术用于修复汽轮机转子汽封轴颈,可极大提高汽轮机转子的性能,降低维修频率,延长使用寿命。     

船用辅汽轮机转子汽封轴颈喷涂WC-12Co涂层的摩擦学性能

采用超音速火焰喷涂技术和电镀技术分别在45钢试件表面制备了WC-12Co涂层和硬铬镀层,测试了涂层、镀层的显微硬度和室温摩擦磨损性能,并观察分析了磨损表面形貌。结果表明:WC-12Co涂层的显微硬度是电镀硬铬层的1.5倍以上;在时间为1.5h,载荷为20N和100N的试验条件下,电镀硬铬层摩擦磨损失质量分别为WC-12Co涂层的3倍和4倍,表明WC-12Co涂层的耐磨性能明显优于电镀硬铬镀层;与硬铬镀层相比,WC-12Co涂层能缩短磨合时间,较快地进入稳定磨损阶段,该阶段因WC-12Co涂层摩擦因数低,波动范围小,更有利于摩擦状态下延长工件的使用寿命。将超音速火焰喷涂技术用于修复汽轮机转子汽封轴颈,可极大提高汽轮机转子的性能,降低维修频率,延长使用寿命。     

HVOF技术制备的WC涂层的耐磨性

采用超音速火焰喷涂技术在45钢基体上制备WC-Co涂层,利用扫描电镜、X射线衍射仪、显微硬度计等设备对所获涂层的组织结构与性能进行分析.并通过磨粒磨损试验研究了WC涂层的耐磨性能.试验结果表明:所获WC-Co涂层与基体金属结合良好,界面处未发现污染.涂层较为致密,其显微硬度在HV1000以上;WC-Co涂层的耐磨性非常优异,经20 min磨损后,其磨损量仅为0.1 g左右;WC-Co涂层的磨损率一直呈下降趋势,与之相对比,电镀硬铬层的磨损率却呈先下降后上升的趋势,所获WC-Co涂层显示了更加稳定的耐磨性.     

AC-HVAF制备WC-10Co-4Cr涂层抗磨粒磨损性能研究

采用活性燃烧高速燃气(AC-HVAF)喷涂工艺制备了WC-10Co-4Cr涂层,测试了涂层的结合强度、显微硬度、气孔率以及抗磨粒磨损性能。并利用XRD对喷涂粉末及涂层进行了相结构分析,用扫描电子显微镜对喷涂粉末、磨粒磨损后的涂层表面形貌进行了观察。结果表明:在喷涂过程中,仅有很少量的WC发生合金化。涂层的结合强度和显微硬度高,组织结构致密。在相同的实验条件下,16Mn钢的磨粒磨损质量损失是WC-10Co-4Cr涂层的266倍,这表明HVAF制备的WC-10Co-4Cr涂层具有优异的抗磨粒磨损性能。     

HVAF喷涂WC-12Co涂层的应用研究

WC-12Co涂层的组织结构主要取决于喷涂工艺,采用活化燃烧一超音速火焰喷涂(HVAF)工艺喷涂WC-12Co涂层。结果表明:HVAF涂层孔隙率为0.6%,表面粗糙度为Ra1.5,HVAF过程中,粉末粒子的扁平化程度高,涂层组织结构均匀;HVAF焰流中WC基本不发生分解,涂层韧性好,HVAF涂层平均硬度达到1 400 HV0.3。     

电阻缝焊法制备铁基WC/金属双层涂层及其摩擦行为

通过电阻缝焊法,使用超硬铁基合金粉末(SHA)和2种粒度(3.5和55μm)的WC粉末在Al7075板表面制备了铁基WC/金属双层涂层。采用SEM和EPMA等手段对双层涂层的显微组织进行了分析;采用纳米压痕仪对双层涂层中微小组织进行了纳米硬度测试;最后通过球盘摩擦(ball-on-disc)实验对比了WC和SUS304 2种磨球对双层涂层的摩擦磨损行为的影响。结果表明,该铁基WC/金属双层涂层的总厚度达600μm,从涂层到基体的结构依次为:WC粉末/铁合金(耐磨层)+铁基/铝合金(金属中间层)+铝合金基体。当以WC为磨球时,使用微细和粗大WC粉末的涂层,其磨损机制分别为严重的磨粒磨损和脆性断裂伴随少量磨粒磨损;当以SUS304为磨球时,使用微细WC的涂层基本未发生磨损,而粗大WC粉末的涂层则发生少量磨粒磨损。以SUS304为磨球时,涂层的磨损率均低于以WC为磨球时涂层的磨损率。     

铸造碳化钨添加量对镍基复合喷熔涂层性能的影响

在镍基合金粉末NiCrBSi中添加不同比例的铸造碳化钨(WC),并采用氧乙炔火焰喷熔工艺在低碳钢表面制备了相应的Ni基WC复合涂层.采用金相显微镜观察了涂层的显微组织,采用湿砂橡胶轮式磨粒磨损试验机测试了涂层的抗磨粒磨损性能,并采用扫描电镜观察了喷熔粉末和喷熔层磨损后的形貌.结果表明:喷熔层的组织为在NiCr合金基体上弥散分布着不同粒度的碳(硼)化物硬质相;涂层的显微组织和WC的含量对Ni基WC喷熔层的硬度和抗磨损性能影响很大,涂层的硬度和抗磨损性能随WC添加量的增加先增加后减小;当WC的含量为35％时,Ni基体WC喷熔涂层的硬度最高,相应的抗磨粒磨损性能最好.     

热喷涂技术替代电镀硬铬的研究进展

从热喷涂技术的发展,高速火焰喷涂(HVOF)涂层的性能,包括耐磨性、耐蚀性、对基体耐疲劳性的影响,热喷涂涂层替代电镀硬铬镀层的成本以及应用4个方面综述了近年来热喷涂技术替代电镀硬铬的研究进展.指出热喷涂技术已经在航空、冶金、包装印刷和造纸等工业领域部分替代了电镀硬铬工艺;由于热喷涂技术对于大工件、厚涂层在性能和价格上的优势,热喷涂技术在其他工业领域的应用也将得到迅速发展.     

Wear,erosion and corrosion resistance of HVOF-sprayed WC and Cr3C2 based coatings for electrolytic hard chrome replacement

Thermally sprayed carbide-based coatings are nowadays extensively considered as an alternative to electrolytic hard chrome (EHC) coatings to reduce the environmental impact and the overall cost associated with EHC process. In this investigation, high-velocity oxy-fuel (HVOF) spray process was employed to prepare coatings using the traditional carbide powders namely the WC-10Co4Cr, the Cr₃C₂-25NiCr and a new type of mixed carbide powder WC-40Cr₃C₂-25NiCr. The Powder deposition rate, basic mechanical properties, abrasive wear, slurry erosion and corrosion resistance of the three coatings were then compared with the EHC coating. The results show that WC-10Co4Cr coating exhibited the highest hardness, abrasive wear and slurry erosion resistance followed by WC-40Cr₃C₂-25NiCr, EHC, and Cr₃C₂-25NiCr coating. The deposition efficiency of the powders as per hierarchy was found to be WC-40Cr₃C₂-25NiCr > WC-10Co4Cr > Cr₃C₂-25NiCr and all the HVOF sprayed coatings exhibited higher corrosion resistance than EHC coating. The highest powder deposition efficiency coupled with low density, acceptable tribo-corrosion performance, as well as low post processing cost makes the HVOF sprayed WC-40Cr₃C₂-25NiCr coating a potential candidate to replace the EHC coating.     

Study of the influence of microstructural properties on the sliding-wear behavior of HVOF and HVAF sprayed WC-cermet coatings

The microstructural properties of WC-Co-Cr and WC-Co coatings deposited by high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) processes were investigated. The tribological behavior of the coatings was studied by means of pin-on-disk tests. Microcracking of the HVOF sprayed WC-Co coatings did not allow preparation of suitable disks for wear tests. The wear rates of the remaining coatings were determined, and wear tracks on the coatings and counterbodies were investigated by SEM. The HVAF sprayed coatings showed greater sliding-wear resistance compared to the HVOF coatings. The prime wear mechanism in the WC-Co HVAF coatings was adhesive wear. The cobalt matrix is lubricious, resulting in very low wear rates and low debris generation. The main wear mechanisms in the WC-Co-Cr coatings were adhesive and abrasive wear. Adhesive wear results in coating material dislodgments (i.e., “pullouts”) that become trapped in the contact zone and act as a third-body abrasive. Particle pullout from the coating significantly increases the wear rate of the coated specimen. The HVAF/WC-Co-Cr coatings exhibited better resistance to particle pullout, resulting in a considerably lower wear rate than the HVOF/WC-Co-Cr coatings.     

Impingement Resistance of HVAF WC-Based Coatings

High-velocity oxygen/air fuel (HVO/AF) WC-17Co and WC-10Co4Cr coatings exhibit great potential in the replacement of electrolytic hard chrome (EHC) plating, and comprehensive properties of such coatings should be superior to those of electrolytic hard chrome plating. The impingement resistance of HVAF WC-based coatings sprayed on 300M ultrahigh-strength steel was studied in this paper. As an important property index, the fracture toughness of HVAF WC-based coatings was measured using the microindentation method at loads of 9.8, 19.6, 24.5, 29.4, and 49.0 N, respectively. The cracks resulting from stress concentration in the microindentation were analyzed. The impingement resistance for two HVAF WC coatings and EHC was evaluated according to the ASTM D 3170 standard, and steel ball free-fall experiment was performed at the height of 0.61, 1.52, 1.83, 2.36, and 2.59 m, respectively. The cracks caused by both impingements were analyzed using scanning electron microscopy (SEM) and optical microscopy (OM) in comparison with the cracks in microindentation test. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

等离子喷涂WC-12Co涂层抗冲刷磨损行为

目的探索WC-12Co复合涂层抗冲刷磨损的能力。方法采用大气等离子喷涂(APS)方法在Q235钢基体上制备WC-12Co复合涂层。用扫描电镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS),对涂层微观形貌和相组成及成分进行分析。采用维氏显微硬度计表征了涂层的力学性能。采用自制的干砂型常温冲刷磨损试验机对涂层进行冲刷磨损实验。结果所制备的涂层主要由WC以及少量的W2C、Co3W3C和Co6W6C相组成。涂层以机械结合方式为主,同时伴有微冶金结合。截面显微硬度高于粘结层,其截面平均显微硬度为1169HV0.05。WC-12Co涂层厚度为300μm,粘结层厚度为50μm。在冲刷角为60°时涂层失重率最大,为0.4788 mg/g;在30°时涂层失重率最小,为0.3696 mg/g。结论在小角度30°冲刷时,具有较好的抗塑性冲刷磨损能力;在冲刷角为60°时出现最大的冲刷失重率,抗冲刷磨损效果较差;在大角度90°时,有一定的抗脆性冲刷磨损性能。     

Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.     

Effect of Nozzle Geometry on the Microstructure and Properties of HVAF-Sprayed WC-10Co4Cr and Cr<Subscript>3</Subscript>C<Subscript>2</Subscript>-25NiCr Coatings

Thermally sprayed hard metal coatings are the industrial standard solution for numerous demanding applications to improve wear resistance. In the aim of improving coating quality by utilising finer particle size distributions, several approaches have been studied to control the spray temperature. The most viable solution is to use the modern high velocity air-fuel (HVAF) spray process, which has already proven to produce high-quality coatings with dense structures. In HVAF spray process, the particle heating and acceleration can be efficiently controlled by changing the nozzle geometry. In this study, fine WC-10Co4Cr and Cr₃C₂-25NiCr powders were sprayed with three nozzle geometries to investigate their effect on the particle temperature, velocity and coating microstructure. The study demonstrates that the particle melting and resulting carbide dissolution can be efficiently controlled by changing the nozzle geometry from cylindrical to convergent–divergent. Moreover, the average particle velocity was increased from 780 to over 900 m/s. The increase in particle velocity significantly improved the coating structure and density. Further evaluation was carried out to resolve the effect of particle in-flight parameters on coating structure and cavitation erosion resistance, which was significantly improved in the case of WC-10Co4Cr coatings with the increasing average particle velocity.     

深振荡磁控溅射复合沉积CrN/TiN超晶格涂层的摩擦学性能

研究了IN718高温合金、WC-6%Co硬质合金和Si(100)基体上深振荡磁控溅射复合沉积CrN/TiN超晶格涂层的摩擦学性能。研究表明,涂层的生长对基体的类型没有选择性。随着基体硬度的升高,划痕结合力失效临界载荷增大,涂层结合力失效机制由翘曲失效转变为基体/涂层协同变形,未发现涂层的剥落失效。载荷为2N时,磨损机制由磨粒磨损和氧化磨损转变为轻微磨粒磨损。载荷为4 N时,IN 718基体上涂层的磨损机制为严重的氧化磨损,WC-6%Co基体上的涂层的磨损机制为磨粒磨损和氧化磨损,氧化物的产生、堆积和转移导致摩擦系数的波动。     

超音速火焰喷涂WC-10Co4Cr涂层的耐滑动磨损行为

采用超音速火焰喷涂(HVOF)工艺制备微米结构WC-10Co4Cr涂层,分别采用金相显微镜、扫描电镜(SEM)、X射线衍射(XRD)和滑动磨损设备分析涂层的微观结构和滑动磨损行为。结果表明:采用液体煤油燃料HVOF喷涂的微米结构WC-10Co4Cr涂层的脱碳程度较低,涂层中仅出现WC和W2C相,而无η相(Co3W3C、Co6W6C)以及软相W。涂层微观结构致密,孔隙率约为1%,平均显微硬度为1 322HV0.3;在相同试验条件下,WC-10Co4Cr涂层的摩擦因数(约0.8)高于不锈钢(1Cr18Ni9Ti)的摩擦因数(约0.5),其滑动体积损失量仅为不锈钢涂层的1/146,具有优异的抗滑动磨损性能。涂层在滑动磨损过程中首先是粘结相的脱落,然后是WC颗粒的磨损。     

HVAF制备WC?12Co涂层的空蚀和磨损性能研究

采用国际上最新的活性燃烧高速燃气喷涂（AC-HVAF）技术制备出WC-12Co金属陶瓷涂层。涂层的X射线衍射检测表明，涂层制备过程中未出现WC粒子的氧化和脱碳现象，涂层相结构基本保持了喂料粉末状态；对制备涂层进行的旋转圆盘空蚀试验表明，WC-12Co硬质涂层抗泥沙磨损性能出色，磨损量仅为不锈钢的1／10；其耐空蚀性能则相反，不及对比0Cr13Ni5Mo不锈钢；对涂层的空蚀破坏机理做了分析，对沙粒磨损损伤特点做了初步探讨。