Ni对TiC-Ni超音速火焰喷涂层组织和耐磨性的影响

Ni对Ti-Ni-C体系SHS反应中的热力学与动力学均有重要影响,Ni在超音速火焰喷涂合成中的作用尚不明确.利用超音速火焰喷涂合成技术制备了3种不同Ni含量的TiC-Ni金属陶瓷涂层,并对涂层进行了组织和性能研究.结果表明,Ni在喷涂过程中起到了吸收反应热、减缓喷涂合成过程中粉末组分的氧化、并在涂层中黏结相金属的作用.原料中的Ni含量对涂层的组织和性能影响较大,Ni含量低涂层中含有大量氧化物,且组织疏松、滑动磨损性能差;随着Ni含量升高到40%时,涂层的氧化物含量降低,滑动磨损性能增强; Ni含量过高,涂层中Ni片层增多,硬质相间距加大,涂层的耐磨损性能有所降低.     

粉末状态对超音速喷涂合成TiC-Ni涂层组织和性能的影响

以Ti粉、Ni粉和石墨为原料通过PVA制粒和混合制粒制备两种喷涂粉末.研究表明:制粒方式在超音速火焰喷涂对涂层组织和耐磨性能有很大影响.PVA制粒粉末进行喷涂,涂层的相组成为TiC、Ni和少量Ti与Ni的氧化物,组织致密具有典型的层状涂层结构特征,涂层耐冲蚀磨损性能较强;混合制粒由于在火焰气流中缺乏SHS反应的条件,粉末喷涂后涂层中含有大量的Ti和Ni的氧化物和少量的粘结相Ni,具有较多的孔洞涂层组织疏松,耐冲蚀磨损性能较差.     

超音速火焰喷涂TiC-TiB2增强Ni基涂层的研究

利用超音速火焰喷涂技术在45号钢基体上制备了2种TiC-TiB2增强Ni基涂层,研究了涂层的组织和性能并与Ni60涂层进行对比分析.结果表明,含Ti-B4C自反应组元粉末的喷涂火焰呈明亮的白炽状态,火焰温度明显高于喷涂Ni60粉末的火焰温度,TiC-TiB2陶瓷增强Ni基涂层的显微硬度和耐滑动磨损性能明显优于Ni60涂层.Ti-B4C-Ni团聚态粉末形成的涂层中陶瓷相均匀分布在金属基体中,颗粒细小,在摩擦过程中不易脱落,有效提高了片层强度和硬度,增强了涂层的耐磨性.而Ti-B4C团聚态粉与Ni60机械混合粉末形成的涂层中出现了明显的金属相与陶瓷相的偏聚现象,使得涂层的结合性和耐磨性略有降低.     

Q235钢表面热喷涂TiB2-50Ni金属陶瓷层的组织结构和性能

目前,对超音速火焰喷涂TiB2增强金属基复合涂层的耐磨性有一定研究,但对其抗热震性能和耐熔融金属腐蚀性能的报道较少.采用机械球磨制备了TiB2-50Ni金属陶瓷复合粉末,通过超音速火焰喷涂技术在Q235钢表面制备TiB2-50Ni金属陶瓷涂层.采用扫描电镜和X射线衍射技术分析了涂层的微观组织和物相,采用HVS-1000显微硬度计测试涂层的硬度值,采用水淬法测试涂层的抗热震性能,并研究了涂层的耐熔融Al-12.07％Si合金腐蚀性及耐磨损性能.结果表明:TiB2-50Ni涂层具有层状结构,组织致密;TiB2-50Ni涂层的主要物相为TiB2和Ni,与喷涂粉末的相同;涂层的硬度值为(348±37) HV3N;涂层与基体结合良好,耐蚀性良好,经60 h的熔融Al-12.07％Si腐蚀后,磨损失重量是Q235低碳钢的1/4;涂层抗热震性能良好,耐磨性较基体明显提高.     

超音速火焰喷涂Ni基涂层组织与性能的研究

采用超音速火焰喷涂技术(HVOF)制备了3种镍基涂层,并研究了涂层的显微组织和性能.结果表明:使用烧结粉末Ni60制备的涂层结合强度、显微硬度均高于包覆粉末Ni包C、Ni包MoS2制备的涂层,Ni包C涂层中产生大量的气体并含有许多的未熔软质相,使得其孔隙率最大,结合强度、显微硬度最低;镍在涂层中起粘结作用,镍含量的增加能显著提高涂层的结合强度和显微硬度;涂层中起减磨作用的MoS2和C相会明显降低涂层的结合强度.     

超音速火焰喷涂Ni基涂层性能的研究

采用超音速火焰喷涂技术方法制备三种镍基涂层，并研究了涂层的显微组织和性能。结果表明：使用烧结粉末Ni60制备的涂层结合强度、显微硬度均高于包覆粉末Ni包C、Ni包MoS2制备的涂层，Ni包C涂层中产生大量的气体并含有许多的未熔软质相，使得其结合强度、显微硬度最4g；镍在涂层中起粘结作用，镍含量的增加能显著提高涂层的结合强度和显微硬度；涂层中的MoS2和C相明显降低涂层的摩擦系数。     

Ni基合金粉末及其非晶涂层的制备与表征

为解决非晶粉末价格昂贵、成型困难等问题,采用真空气雾化法制备了Ni FeCrMoNbBSi合金粉末,利用火焰喷涂焰流温度高、冷凝速度快有利于形成非晶相等特点,经火焰喷涂后制备了镍基非晶涂层。通过XRD、SEM、EDS、TEM等对粉末和涂层的相组织结构、表面形貌和微观特征进行了表征。结果表明:Ni FeCrMoNbBSi合金粉末形貌为球形或近球形,主要由晶体相FeNi3和Ni CrFe固溶体组成,非晶含量较少。制备的Ni基非晶涂层组织结构致密,主要由非晶相和Cr2Ni3金属间化合物组成,非晶含量可达70%(体积分数)。     

Ti-Ni低温超音速火焰喷涂层及激光处理后的特征

低压等离子喷涂制备的Ti-Ni涂层性能优异,但成本高、效率低.以镍包钛为粉末,采用低温超音速火焰喷涂技术制备了Ti-Ni涂层,并在惰性气氛保护下对涂层进行激光后处理,从而获得了致密的Ti-Ni涂层.对粉末、喷涂态涂层和激光处理态涂层的结构和相组成进行了表征.结果表明:喷涂态Ti-Ni涂层次表面结构较为疏松,但内部结构致密;涂层以Ni作为Ti的黏结相,Ti没有发生熔融和铺展开,两者没有发生合金化;经激光处理后,涂层表面和内部的致密度明显提高,涂层中以TiNi和Ti2Ni合金相为主,但还含有少量的Ni相存在.     

高硬度耐磨损电弧喷涂涂层研究

采用电弧喷涂方法制备的高硬度耐磨损JCW-B涂层可广泛应用于工业零部件耐磨表面.对涂层的组织、孔隙率、硬度、结合强度及耐磨粒磨损性能进行分析,对比研究该涂层与Ni60喷熔层的耐冲蚀性能.结果表明JCW-B涂层组织致密,孔隙率低于4%,显微硬度HV0.1高于1200,平均结合强度大于50MPa.研究了涂层的耐磨损机理,XRD结果显示涂层中主要含有Fe3B硬质相,对涂层起到弥散强化的作用.     

反应火焰喷涂TiC/Fe复合涂层显微结构研究

采用前驱体碳化复合技术制备Ti-Fe-C系反应喷涂复合粉末,通过反应火焰喷涂技术成功制备了TiC/Fe基金属陶瓷复合涂层.利用XRD和SEM对喷涂粉末和涂层的成分、组织结构进行了分析,考察了喷涂粉末粒度、Ti的加入方式对涂层组织结构的影响.研究结果表明:所制备的TiC/Fe复合涂层由不同含量TiC颗粒分布于晶粒内部而形成的晶内型复合强化片层组织叠加而成,TiC颗粒呈纳米级;喷涂粉末粒度较大时,制备的涂层中出现有害相Fe2Ti,片层厚度较大,孔隙率高;以纯Ti粉为Ti源制备的喷涂粉末和以TiFe粉为Ti源制备的喷涂粉末相比较,其涂层中硬质相TiC含量较少,孔隙率较大.     

Mo2Ni3Si/NiSi复合材料涂层的滑动磨损行为

以Mo-Ni-Si合金粉末为原料，使用激光熔敷技术在1Crl8Ni9Ti不锈钢基材表面制备出Mo2Ni3Si／NiSi金属硅化物复合材料涂层．应用OM，SEM，EDS和XRD方法分析了涂层的显微组织．Mo2Ni3Si／NiSi复合材料涂层由初生的Mo2Ni3Si三元金属硅化物树枝晶和枝晶间的Mo2Ni3Si／NiSi共晶组织组成．在常温和高温滑动磨损条件下测试了涂层的耐磨性能．在常温滑动磨损条件下，Mo2Ni3Si／NiSi金属硅化物复合材料涂层的质量损失随着载荷的增加缓慢增加；在高温滑动磨损条件下，Mo2Ni3Si／NiSi金属硅化物复合材料涂层的质量损失随着温度的升高缓慢下降．     

Characteristics and performance of hard Ni60 alloy coating produced with supersonic laser deposition technique

A novel coating fabrication technique, known as supersonic laser deposition (SLD), which combines cold spray (CS) with laser technology, is applied to produce hard Ni60 (58–62 HRC) coating on medium carbon steel (AISI 1045 steel) substrate. Different process parameters are investigated to obtain the optimal. The Ni60 coating specimens prepared by SLD process are studied microstructurally using scanning electron microscope (SEM), energy dispersive spectrum (EDS) and X-ray diffraction (XRD). The microstructures of the coatings are compared with those of the coatings produced using laser cladding (LC). The hardness, tribological property and corrosion resistance of the Ni60 coatings produced by SLD and LC with the optimal process parameters are evaluated under Vickers hardness, pin-on-disk wear and electrochemical corrosion tests. It is demonstrated that the Ni60 coating with SLD exhibits some characteristics, such as fine microstructure as cast, stable phases and less dilution; it surpasses the coating produced with conventional LC process in sliding wear resistance; but in 1 mol/L H₂SO₄ solution, the SLD and LC coatings performed similarly in corrosion resistance. This research has proved that SLD technique enables depositing hard Ni60 on steel substrate, which is impossible for CS technique.     

The microstructure and wear resistance characteristics of electroformed nickel and partially stabilized zirconia composite coatings

Ni-PSZ composite coatings with various PSZ particle content were prepared by the electroforming technique. The microstructure and surface components of the coatings have been examined by optical microscopy, electron microscopy and X-ray photoelectron spectroscopy analysis and the wear properties of the coatings tested on a reciprocating wear test machine. The results show that the PSZ particles are uniformly dispersed in the coatings and thus increase the wear resistance of the coatings by inhibiting plastic deformation of the nickel matrix. The co-deposition of the PSZ particles in the electrolyte is mainly in the form of agglomeration and is accompanied by the incorporation of Ni(OH)₂. When the PSZ content in a coating is higher than a critical value, the wear resistance of the coating could deteriorate because of the decrease in the integrity of the nickel matrix. After heat-treatment at high temperature, Ni(OH)₂ in the coating is turned into Ni₂O₃ and NiO which can wet the PSZ particles and increase the bonding strength between the PSZ and nickel. In addition, the agglomerated PSZ particles are sintered when heat-treated. These are all beneficial to increasing the wear resistance of the coating.     

Preparation of Oil-Encapsulated Microcapsules and Tribological Property of Ni Composite Coating

Microcapsules containing oil are potential candidate materials for preparing electrocomposite coatings with excellent tribological properties. In the present study, the preparation of oil-encapsulated microcapsules and electrodeposition of Ni-microcapsule composite coating are presented along with the properties of the coating. In situ interfacial polymerization method was used for the preparation of lubricating oil-encapsulated urea-formaldehyde microcapsules. The synthesized microcapsules were incorporated into the nickel matrix by electrodeposition using Ni-Watts bath. The Ni-composite coating containing microcapsules exhibited smaller Ni grain size, higher microhardness and lower surface roughness compared to plain Ni coating. Electrodeposited Ni coating containing oil-encapsulated microcapsules exhibited improved tribological properties with lower wear loss and coefficient of friction compared to plain nickel coating.     

Hardness,wear resistance and bonding strength of nano structured functionally graded Ni-Al2O3 composite coatings fabricated by ball milling method

Using initial powder mixtures with different Ni:Al₂O₃ weight ratios ranging from 1:1 to 16:1, nano structured Ni-Al₂O₃ composite coatings were deposited onto an aluminum plate by means of a planetary ball mill. It was shown that initial charges with Ni:Al₂O₃ weight ratios of 4:1 and greater, yielded well-compact coatings. Coating deposited from the powder charge with Ni:Al₂O₃ weight ratio of 4:1, contained 20?vol% of alumina particles in the Ni matrix and submitted the highest hardness value (657?±?28?Hv) and wear resistance. Nevertheless, composite coating containing smallest amount of alumina particles showed the highest cohesive strength of 9.8?±?0.3?MPa. In the next step, nano structured functionally graded composite coatings were produced by the deposition of two separate layers containing different amounts of alumina particles. Although the graded coating showed superior hardness and wear resistance compared with the non-graded coatings, it suffers from low cohesive strength attributed to the presence of alumina particles at the interface region between the two layers. To overcome the poor adhesion between two layers, a thin intermediate plain Ni one was deposited between two layers leading to 80% and 30% improvement in the adhesion strength and wear resistance, respectively.     

Enhancement of oxidation and wear resistance of Fe-based amorphous coatings by surface modification of feedstock powders

Surface oxidation of the in-flight powders during the preparation of amorphous coatings in high velocity oxygen fuel process causes the formation of oxygen-rich intersplat regions. These regions are brittle in nature and can dramatically deteriorate the mechanical performance of the coatings. To solve this problem, the starting FeCrMoCBY amorphous feedstock powders were modified by electroless plating a thin layer of Ni–W–P amorphous phase. It was found that the covering of the Ni–W–P layer can significantly reduce the oxygen content in the resultant Fe-based amorphous coatings. The wear resistance of the coatings with and without the modification of Ni–W–P thin layer was comparatively studied by ball-on-disk wear tests against Si₃N₄ counterpart in air. It revealed that the wear of two types of coatings follows the same oxidation wear mechanism but the modified coating exhibits much better wear resistance due to the improved oxidation resistance.     

Effect of Mo on the VC–VB particles reinforced Fe-based composite coatings

VC–VB particles reinforced Fe-based composite coatings with different molybdenum contents were in-situ fabricated by laser cladding. The microstructure and properties of the coatings were systematically investigated by means of micro hardness tester, XRD, SEM, EDS, ring-block wear testing machine and box-type resistance furnace. The results showed that both hardness and wear resistance of the coatings were greatly improved. When the content of Mo exceeds 3%, anti-oxidation of the coating decreased. Through analysing of the oxidation kinetics curves at different temperatures of the samples, it can be found that the coating with 2.5% Mo has the preferable oxidation resistance at 600°C, and its antioxidant property is five times of the coating without Mo, two times of the substrate.     

Influence of Ni content on the structure and properties of Cr-Ni-N coatings prepared by direct current magnetron sputtering

Cr-Ni-N coatings were deposited on 304 stainless steel substrates using a conventional direct current magnetron reactive sputtering system in nitrogen-argon reactive gas mixtures. The influence of Ni content (0 ≦ x ≦ 20 at.%) on the coating composition, microstructure, and tribological properties was investigated by glow discharge optical spectroscopy, X-ray diffraction and transmission electron microscopy, scanning electron microscopy (SEM), nano-indentation, and pin-on-disk tests. The results showed that microstructure and properties of coatings changed due to the introduction of Ni. The ternary Cr-Ni-N coatings exhibited solid solution structures in spite of the different compositions. The addition of Ni strongly favoured preferred orientation growth of <200>. This preferred orientation resulted from the formed nano-columns being composed of grains with the same crystallographic orientation, as confirmed by SEM cross-sectional observations. The mechanical properties including the nano-hardness and reduced Young's modulus decreased with increasing Ni content. Pin-on-disk tests showed that low Ni content coatings presented higher abrasion resistance than high Ni content coatings.     

Fabrication of Ni60–SiC coating on carbon steel for improving friction,corrosion properties

The Ni60 and SiC–Ni60 composite coatings were successfully obtained by high-frequency inductive cladding on the AISI 1045 steel surface. The influence of SiC nanoparticles on the morphologies, phase composition, micro-hardness, wear resistance and corrosion resistance of the coatings were investigated systematically. An ultrasonic-assisted method was pre-treated for homogenising coating. The performance tests of coatings indicated that high-quality metallurgical bonding was formed under the optimised parameters. The average micro-hardness of Ni60 and SiC–Ni60 coatings was 765.6 and 1072.4?HV, respectively. The corresponding wear resistance was also measured, and the composite coating showed a much lower friction coefficient and wear rate. The corrosion resistance of the coatings was evidently improved by the addition of SiC nanoparticles.