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。     

Tribological Performance of TiB2-Ni Composite Coating Deposited by APS

TiB2-Ni composite powders were prepared by pressurized hydrogen reduction cladding with different proportion of TiB2.The coatings were then prepared by APS.The microstructures and the phase composition of the powders as well as the deposited coatings were analyzed by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The coatings were tested using a ring-on-disc tribometer from ambient temperature to 300°C.A sprayed Cr3C2-NiCr coating was tested as a reference.The morphologies of the worn surface of the coatings were observed and analyzed.It is found that the TiB2-Ni composite coatings present higher friction coefficient than that of the Cr3C2-NiCr coating at room temperature due to the adhesive wear mechanism,whereas the main wear mechanism of Cr3C2-NiCr coating is rupture and exfoliation.However,at high temperature,the friction coefficient of the TiB2-Ni composite coating decreases as a result of B2O3 solid lubricant,which alleviates the adhesive wear on coatings.Furthermore,the TiB2-Ni composite coating greatly reduces the mass loss of the boron cast iron.     

Wear behaviour of thermal flame sprayed FeCr coatings on plain carbon steel substrate

The principle aim of this study is to investigate the wear behaviour of FeCr coatings on Ni-based bond deposited plain carbon steel substrate for several applications in power generation plants. For this purpose, FeCr and Ni-based powders were sprayed on plain carbon steel substrates using a thermal flame spray technique. Fabricated layers were characterized by using a X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), microhardness and surface roughness testers. FeCr coatings were subjected to sliding wear against AISI 303 stainless steel counter bodies under dry and acidic environments. A pin-on-plate type of apparatus was used with normal loads of 49 and 101 N and sliding speed of 1 Hz. XRD results revealed that FeCr, Fe, Cr, Fe–Cr–Ni, γ-Fe₂O₃ and Fe₃O₄ phases are exist in the coating. In addition, some inhomogenities such as oxides, porosity, cracks, unmelted particles and inclusions were observed by SEM. The surface morphologies of FeCr samples after wear experiments were examined by SEM and EDS. It was found that friction coefficients of the coatings in dry condition are higher than that in acidic environment.     

铬锆铜表面等离子喷涂Cr3C2p/NiCr涂层的组织与性能

采用等离子喷涂技术在铬锆铜(CrZrCu)基体表面制备了Cr3C2 p/NiCr涂层。利用X射线衍射仪(XRD)、扫描电镜(SEM)等仪器研究了涂层的显微组织及结构,采用磨粒磨损试验机对Cr3C2 p/NiCr涂层与电镀NiCo层的磨损性能进行了测试比较。结果表明:涂层组织呈片层状结构,在NiCr合金片层上分布着未熔的Cr3C2和Cr7C3、Cr2Ni3、CrNi析出相。与电镀Ni-Co镀层相比,Cr3C2 p/NiCr涂层具有较高的硬度和耐磨粒磨损性能,其磨损量仅为电镀层的35%。     

Microstructure and Wear Resistance Evolution of HVOFSprayed WC-（W,Cr）2C-Ni Coating with Post Heat Treatment In Air Atmosphere

WC-(W,Cr)2C-Ni coating was prepared on 1Cr18Ni9Ti stainless steel and C-276 Ni-base Hastelloy by high velocity oxy-fuel(HVOF)spraying.The effect of post heat treatment in air atmosphere on the microstructure,phase composition,microhardness,fracture toughness,and wear resistance of HVOF-sprayed WC-(W,Cr)2C-Ni coating was investigated.The microstructure and phase composition of the coatings were analyzed by means of field emission scanning electron microscopy(FESEM)and X-ray diffraction(XRD).The microhardness and fracture toughness of the coatings were measured using a microhardness tester and a Vickers hardness tester.Moreover,dry friction and wear behavior of the coatings sliding against Si3N4 ball was investigated using an oscillating friction and wear tester;and the worn surfaces of the coatings were analyzed by means of scanning electron microscopy(SEM).It was found that heat treatment within 500-800°C resulted in crystallization of amorphous phase in as-sprayed coating,generating nanoscale new phases such as NiWO4,CrWO4 and Cr2WO6.Besides,heat treatment led to increase of the microhardness of as-sprayed coating,and the highest microhardness was obtained after heat treatment at 800°C.The fracture toughness and wear resistance of the as-sprayed coating increased with increasing heat treatment temperature up to 700°C but tended to decrease with further elevating temperature.In other words,the mechanical properties and wear resistance of the as-sprayed coatings were worsened owing to excessive growth of oxidation grains and depletion of ductile Ni binder after heat treatment above 700°C.Thus it was suggested that as-sprayed ceramic composite coating should be post heat treated in air at a moderate temperature of 700°C so as to achieve the optimized mechanical properties and wear resistance.     

钛合金激光熔覆TiB-TiC增强TiNi-Ti2Ni金属间化合物复合涂层的组织和耐磨性（英文）

以Ti＋Ni＋B4C粉末混合物为原料,利用激光熔覆技术在TA15钛合金基材表面制得TiB-TiC共同增强TiNi-Ti2Ni金属间化合物复合涂层。采用OM、SEM、XRD、EDS及AFM等手段分析激光熔覆涂层的显微组织及磨损表面,测试涂层的室温干滑动磨损性能。结果表明,激光熔覆TiB-TiC增强TiNi-Ti2Ni金属间化合物复合涂层熔覆具有独特的显微组织,菊花状的TiB-TiC共晶均匀分布在TiNi-Ti2Ni双相金属间化合物基体中。由于高硬、高耐磨TiB-TiC陶瓷相与高韧性TiNi-Ti2Ni双相金属间化合物基体的共同配合,激光熔覆涂层表现出优异的耐磨性。     

FeS固体润滑涂层的结构分析及磨损行为比较

新型固体润滑剂FeS涂层的优异减摩耐磨性能与制备工艺密切相关，利用低温离子渗硫和高速火焰喷涂的方法制备了FeS固体润滑涂层。在MM-200和QP-100磨损实验机上对比研究了这两种涂层的摩擦磨损行为。利用XRD分析了涂层的相结构，用SEM观察了涂层的表面、截面及磨面形貌，用划痕仪测定了涂层与基体的结合力。结果表明，离子渗硫FeS涂层的减摩性和耐磨性更好，而热喷涂层的抗擦伤性更佳，这是两种FeS涂层的组织结构不同所致。     

Erosion-corrosion properties of different WC-Co-Cr coatings deposited by the HVOF process—influence of metallic matrix composition and spray powder size distribution

WC-Co-Cr coatings were sprayed by the High Velocity Oxygen Fuel (HVOF) process and characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD) and erosion corrosion tests. Powders with different relative amounts of Co and Cr in the matrix and different powder grain size distributions were examined. At constant spray conditions the powders gave coatings of different quality as regards erosion-corrosion performance. At low erosive conditions the erosion-corrosion resistance increased when increasing Cr-content from 5 to 8.5 wt.%. However, when the erosivity was increased by increasing test velocity, an increase of Cr content from 5 to 8.5 wt.% showed no improvement in coating quality. Powder grain size distribution was found to be an important parameter, strongly affecting the coating quality. Powders with narrow grain size distributions gave coatings of higher quality than powders with wider grain size distributions. A reduction of the heat input during spraying reduced the degree of WC decomposition and improved the coating properties when the spray powder contained a large fraction of small grains.     

High-velocity oxyfuel reactive spraying of mechanically alloyed Ni-Ti-C powders

Recently, there has been considerable interest in producing cermet coatings with nanoscale carbide grains in the size range 50 to 500 nm. In this article, the production of nanoscale TiC grains in a Ni-based alloy matrix by reactive high-velocity oxyfuel (HVOF) spraying of metastable Ni-Ti-C powder is reported. Mechanical alloying of a Ni(Cr) prealloyed powder and Ti and C elemental powders was performed in a planar-type ball mill, and materials were characterized in detail using x-ray diffraction (XRD) and scanning electron micros-copy (SEM). Phase changes were correlated with milling time and other processing conditions. Results show that, by the selection of appropriate conditions, a metastable Ni-Ti-C powder could be obtained with the nominal composition 50wt.%Ni-40wt.%Ti-10wt.%C. Following sieving and classification, powder was produced with a particle size range of −38 to 8 μm, which is suitable for HVOF spraying. Coatings, approximately 250 μm thick, were deposited by HVOF spraying onto mild steel substrates, and the microstructures formed were investigated. XRD showed that a self-propagating high-temperature synthesis (SHS) reaction had occurred in the powder particles during spraying and that the principal phases present in the coating were TiC and a Ni-rich solid solution; small quantities of NiTi, TiO₂, and NiTiO₃ were also present. SEM revealed that the coatings had a characteristic, splatlike morphology and that TiC formed as a nanoscale dispersion, with a size range of ∼50 to 200 nm, within solidified splats. The microstructures of these reactively sprayed Ni-TiC coatings are briefly compared with those observed in HVOF-sprayed coatings deposited using prereacted SHS powder. The original version of this paper was published as part of the ASM Proceedings, Thermal Spray 2003: Advancing the Science and Applying the Technology, International Thermal Spray Conference (Orlando, FL), May 5–8, 2003, Basil R. Marple and Christian Moreau, Ed., ASM International, 2003.     

大气等离子喷涂TiB2-TiC-Co涂层的组织与性能

利用Co-Ti-B4C自蔓延体系合成TiB2-TiC-Co复合陶瓷粉末，并结合大气等离子喷涂技术在Q235 钢基体表面制备TiB2-TiC-Co陶瓷涂层，研究了自蔓延产物和涂层的相组成、显微组织，以及涂层的结合强度和抗磨损性能。结果表明：Co-Ti-B4C体系自蔓延产物的物相中，除了少量剩余的NaCl添加剂衍射峰外，主要由TiB2和TiC陶瓷相的强衍射峰组成；产物断面中，两相陶瓷颗粒细小。随Co含量增加，TiB2-TiC-Co涂层表面盘状组织增多，表面逐渐平滑，截面涂层厚度均匀，组织致密性逐渐增加；结合强度和耐滑动磨损性能呈先升高后降低的变化趋势。Co含量为10wt.%时，涂层的结合强度和耐滑动磨损性能最好，涂层的滑动磨损机制主要为粘着磨损和层状剥落磨损。     

等离子熔覆NiCr-Cr3C2复合涂层摩擦磨损性能的研究

目的研究碳化铬含量及磨损载荷力对复合涂层摩擦磨损性能的影响,探究不同磨损载荷下的磨损机制。方法采用5种Ni55和NiCr-Cr_3C_2的混合粉末(Ni Cr-Cr_3C_2质量分数分别为10%、20%、30%、40%、50%),通过等离子熔覆技术制备金属基复合涂层。采用XRD、SEM对涂层物相进行检测分析,使用Rtec万能摩擦磨损试验机对复合涂层表面进行不同载荷下的摩擦磨损性能测试。对涂层组织、摩擦系数、磨损体积及磨损表面微观形貌进行对比分析,探究碳化铬的含量以及摩擦载荷对复合涂层摩擦磨损性能的影响。结果 NiCr-Cr_3C_2在熔覆过程中发生熔化,XRD测得涂层中的碳化物主要以Cr_7C_3为主,其他主要物相包括Cr_3C_2、Cr_(23)C_6、Cr_5B_3、Ni_3Si。复合涂层的硬度及耐磨性能随着碳化铬含量的增加而增大,硬度最高达1500HV以上,耐磨性是基体Q235的2～16倍。当磨损载荷低于80 N时,主要发生磨粒磨损;当磨损载荷为100 N时,主要发生粘着磨损和磨粒磨损,其中S5的磨损机制为疲劳磨损和磨粒磨损。结论加入碳化铬,随着碳化铬含量增加,复合涂层的耐磨性不断提高,并且随着磨损载荷的增大,涂层磨损机制发生转变。     

Microstructural characterization and hardness evaluation of HVOF sprayed Ni–5Al coatings on Ni- and Fe-based superalloys

HVOF sprayed Ni–5Al coatings on Ni- and Fe-based superalloy substrates were characterized to assess the microstructural features and strength in the as deposition condition for their applications in high-temperature corrosive environment of gas turbine. X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), and X-ray mapping analysis are used to characterize the Ni–5Al coatings. The dense coatings with less porosity and inclusions were produced using HVOF process. The deposited Ni–5Al coatings exhibited splat like layered morphologies due to deposition and resolidification of successive molten and semi molten powder particles. The hardness of coatings on three different superalloy substrates was measured and it was in the range of 210–272 Hv. The average bond strength and surface roughness of the as-sprayed coatings were 42.62 MPa and 9.22–9.45 μm, respectively. Diffusion of alloying elements from the substrate into the coating has occurred in all the three superalloy substrates as observed from the X-ray mapping analysis.     

Influence of Plasma Intensity on Wear and Erosion Resistance of Conventional and Nanometric WC-Co Coatings Deposited by APS

The effects of plasma intensity and powder particle size on wear and erosion resistance have been evaluated for WC-12 wt.%Co coatings deposited by Air Plasma Spraying. Coatings were deposited from micrometric and nanostructured powders. SEM and XRD characterization showed the presence of WC, W₂C, W, and an amorphous Co-rich matrix. The performance of the different coatings was compared in sliding wear tests (ball-on-disk), under dry friction conditions. Wear debris and tracks were analyzed by SEM. The debris generated during the test was found to have a great influence on the sliding properties. Wear follows a “three-body abrasive mechanism” and is dominated by coating spallation because of sub-surface cracking. In order to evaluate erosion behavior, solid particle erosion tests were conducted. Eroded coatings were analyzed by SEM, and erosion mainly occurs by a “cracking and chipping mechanism.” The study shows that wear and erosion behavior is strongly affected by plasma arc intensity.     

汽车活塞环表面Ni60A-Cr2O3复合涂层的制备与性能

采用超声速等离子喷涂法在汽车活塞环用45钢表面制备了Ni60A-Cr2O3复合涂层,通过X射线衍射(XRD),扫描电镜(SEM),摩擦磨损试验,电化学试验和浸泡腐蚀试验研究了Cr2O3含量对Ni60A-Cr2O3复合涂层物相组成、显微组织、耐磨性能和耐腐蚀性能的影响。结果表明:Ni60A-Cr2O3复合涂层中除有增强相Cr2O3外,还含有FeNi3、Fe(C,B)6和Cr23C6等含Cr析出相;随着复合涂层中Cr2O3含量的增加,复合涂层的磨损量呈现先减小而后增加的趋势,在Cr2O3质量分数为35%时磨损量最小,Ni60A-Cr2O3复合涂层中适宜的Cr2O3添加量为35%;Ni60A涂层和35%Cr2O3+65%Ni60A复合涂层的磨损机制分别为黏着磨损和磨粒磨损;极化曲线测试结果和浸泡腐蚀试验结果都表明,在1.5mol/L H2SO4和3.5%NaCl溶液中,35%Cr2O3+65%Ni60A复合涂层的耐腐蚀性能都要优于Ni60A涂层的。     

金属Cr层对Cr/Cr2N纳米多层涂层的性能影响

目的研究金属Cr层对Cr/Cr_2N纳米多层涂层结构和性能的影响,为多层硬质涂层在海洋等腐蚀性介质中的应用提供理论基础。方法采用多弧离子镀技术制备一系列不同金属Cr层厚度的Cr/Cr_2N纳米多层涂层,采用XRD、SEM、纳米压痕及划痕仪测试了多层涂层的结构、微观形貌和机械性能。采用电化学工作站评价了Cr/Cr2N纳米多层涂层在海水环境下的电化学行为,并采用摩擦实验机测试了涂层在海水环境下的摩擦学性能。结果 Cr层对Cr/Cr_2N纳米多层涂层的结构产生了一定的影响。不同Cr层厚度的Cr/Cr_2N纳米多层涂层在海水环境下的磨损率差别不大,均约为1.2×10-6 mm~3/(N·m),具有良好的耐磨损性能。Cr层厚度约为21 nm的Cr/Cr2N纳米多层涂层在海水环境下具有较高的阻抗值,呈现出较高的耐腐蚀性能。结论一定厚度的金属层(如Cr层厚度约为21 nm)和界面是多层涂层呈现较高耐腐蚀性能的关键。Cr/Cr2N纳米多层涂层在海水环境下良好的耐腐蚀和耐磨损性能,使其可应用于海洋等腐蚀性介质中,并发挥良好的表面防护作用。     

Microstructure refinement and alloying of WC-CoCr coatings by electron beam treatment

The corrosion and wear behaviour of HVOF (high velocity oxygen fuel) sprayed WC-CoCr (cermet) coatings were investigated before and after electron beam (EB) remelting. In this regard, the coatings were deposited on INCONEL 617 substrate. The mentioned Ni-based alloy is well known for its good corrosion behaviour in chloride containing media but exhibits not enough good wear properties.The paper investigates the influence of EB-remelting process on sliding wear respectively on corrosion resistance in 1 M NaCl solution of the alloyed surface. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) were performed before respectively after the EB-treatment in order to investigate the coating morphology as well as the phase modification achieved through the alloying process. Tribological tests concerning the sliding wear behaviour of the tested materials revealed a significant decrease of the wear rate for both the as-sprayed coating respectively the alloyed surface in comparison with the base material. However, the as-sprayed cermet coating exhibits the lowest wear rate among the investigated samples.The microhardness of the alloyed surface was higher (1100 HV₀₃) in comparison with that of the as-sprayed cermet coating (905 HV₀₃) as a result of new phase formation (especially the η-Co₄W₂C). The corrosion behaviour in salt water of the EB remelted surface was also considerably improved in contrast to the as-sprayed cermet coating.     

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.     

Microstructure and properties of AC-HVAF sprayed Ni60/WC composite coating

A Ni60/WC coating was deposited on 0Cr13Ni5Mo stainless steel substrate by the actived combustion-high velocity air fuel (AC-HVAF) technique. The structure and morphologies of the Ni60/WC coating were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the wear resistance and corrosion resistance were studied. The results showed that the AC-HVAF spraying was seen as the pre-eminent process for the deposition of Ni60/WC coating. Due to low particle heating and high particle velocity in the HVAF process, WC phase remain almost unchanged after spraying. The tribological behaviors were evaluated by using a HT-600 wear test rig. Under the same conditions, the worn volume of 0Cr13Ni5Mo stainless steel was 10.43 times more than that of the coating. The wear mechanism was mainly fatigue wear. A series of the electrochemical tests was carried out in a 3.5 wt.% NaCl solution in order to examine the corrosion behavior. Mechanisms for corrosion resistance were discussed.     

等离子喷涂与超音速火焰喷涂NiCr-Cr3C2涂层组织与摩擦磨损性能研究

目的 研究等离子喷涂与超音速火焰喷涂NiCr-Cr3C2涂层的组织、力学性能和摩擦磨损性能。方法 采用等离子喷涂与超音速火焰喷涂工艺制备NiCr-Cr3C2涂层,并采用X射线衍射仪（XRD）、扫描电镜（SEM）、万能试验机、显微硬度计和高速往复摩擦磨损试验机,系统地分析了两种工艺所得涂层的物相、组织、结合强度、硬度及摩擦磨损性能。结果 两种工艺制备的NiCr-Cr3C2涂层与基体界面结合效果良好。等离子喷涂NiCr-Cr3C2涂层为层片状组织,层间可见微裂纹,孔隙率较高;超音速火焰喷涂NiCr-Cr3C2涂层组织均匀,无明显微裂纹,可见少量微小孔隙。物相分析表明,等离子喷涂涂层由NiCr、Cr3C2和Cr7C3相组成,而超音速火焰喷涂涂层由NiCr和Cr3C2相组成。超音速火焰喷涂NiCr-Cr3C2涂层的耐磨性优于等离子喷涂涂层,等离子喷涂涂层和超音速火焰喷涂涂层的稳态摩擦系数分别为0.4和0.6。随载荷升高,两种工艺制备的NiCr-Cr3C2涂层摩擦系数均显著下降。磨损后,等离子喷涂NiCr-Cr3C2涂层表面具有明显的凹痕和剥落,而超音速火焰喷涂NiCr-Cr3C2涂层磨痕表面较光滑,未见明显剥落。两种工艺制备的涂层磨损机制均为磨粒磨损和疲劳磨损。结论 超音速火焰喷涂NiCr-Cr3C2涂层较等离子喷涂涂层组织更为致密,具有更为优良的综合力学性能和耐磨性,等离子喷涂制备的NiCr-Cr3C2涂层的减摩性较好。     

Microstructure and tribological properties of laser clad Ti2Ni3Si/NiTi intermetallic coatings

Wear resistant Ti₂Ni₃Si/NiTi full intermetallic composite coatings with a microstructure consisting of ternary metal silicide Ti₂Ni₃Si primary dendrites and interdendritic Ti₂Ni₃Si/NiTi eutectic were fabricated on a substrate of 0.2%C low carbon steel by the laser cladding process using Ti-Ni-Si alloy powders as the precursor materials. Microstructure of the coatings was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the laser clad Ti₂Ni₃Si/NiTi intermetallic coatings was evaluated under dry sliding wear test conditions at room temperature. Results indicate that the Ti₂Ni₃Si/NiTi intermetallic coatings have excellent abrasive and adhesive wear resistance under dry sliding wear test conditions because of the unique combination of high yield strength and toughness of the intermetallic compound NiTi and the high hardness, strong covalent dominant atomic bonds and possible strong hardness anomaly of the ternary metal silicide Ti₂Ni₃Si with MgZn₂ type Laves crystal structure.