原位生成 WC-B4C 增强镍基激光熔覆层及其性能研究

目的通过激光熔覆技术,在Q235钢表面原位生成WC-B4C增强镍基熔覆层。方法以WO3,B2O3,C和Ni60混合粉末为预涂原料,采用激光熔覆技术原位生成WC-B4C增强镍基熔覆层,对熔覆层的显微组织和物相构成进行分析,研究其摩擦磨损性能。结果采用合适的工艺参数,通过原位生成WC-B4C形成的增强镍基涂层形貌良好,与基材呈现较好的冶金结合。熔覆层平均硬度1200HV0.3,摩擦磨损失重仅为纯Ni60熔覆层的1/3。结论熔覆层硬度较高,耐磨性很好。大量原位生成的WC-B4C增强相及其均匀分布是熔覆层硬度和耐磨性提高的原因。     

Y2O3对原位自生TiC增强Ni基涂层组织和性能影响

采用氩弧熔覆的方法,以Ni60A自熔性合金粉末为粘结相,添加Ti粉、C粉和不同含量的稀土氧化物Y₂O₃,在16Mn钢基体上制备出TiC陶瓷颗粒增强金属基熔覆涂层. 运用XRD, SEM等手段对复合涂层的显微组织进行表征和分析,并对熔覆涂层的硬度及耐磨性进行了测试. 结果表明,适量添加Y₂O₃可以使涂层组织中枝晶的方向性减弱、同时细化涂层组织,使涂层组织更加均匀,涂层的硬度和耐磨性有显著提高. 添加2% Y₂O₃熔覆涂层的组织为最细,涂层具有较高的显微硬度和良好的耐磨性能.     

TC4钛合金表面激光熔覆WC增强镍基复合涂层的组织及耐磨性

为提高TC4钛合金的耐磨性,利用激光熔覆技术(laser cladding,LC)在TC4钛合金表面制备Ni60+50%WC(体积分数)和deloro22(d22)粉末打底+(Ni60+50%WC)2种耐磨复合涂层。采用扫描电子显微镜(SEM)、能谱仪(EDS)以及X射线衍射仪(XRD)来表征涂层的微观结构和物相组成;使用HV-1000显微维氏硬度计、HRS-2M型高速往复摩擦磨损试验机和WDW-100D电子万能试验机来分析涂层的性能。结果表明:2种涂层均由W₂C、TiC、Ni₁₇W₃、Ni₃Ti和Ti_xW_1-x相组成,2种涂层不仅与基体呈现出优异的冶金结合,而且组织均匀致密,没有裂纹瑕疵;由于涂层中存在着原位合成的硬质相和细晶强化共同作用使得涂层硬度显著提高,约为TC4基体的2.82倍;2种涂层的摩擦系数(COF)和磨损量都远低于TC4钛合金基体;Ni60+50%WC复合涂层和d22粉末打底+(Ni60+50%WC)复合涂层的抗剪切结合强度分别为188....     

Effect of compositions on the microstructure and properties of plasma clad NiAl coating

NiAl intermetallic coating was in-situ synthesized by the plasma cladding process. The effect of atomic ratio of Ni to Al atoms 1 (coating 1), 2 (coating 2) and 3 (coating 3) on the microstructure and mechanical properties of plasma clad was studied by combining microstructural analysis and wear-resistant test. The obtained results indicated that the microstructure of the synthesized NiAl coating was compact and uniform in addition to few porosities and the NiAl coating well metallurgically bonded with the substrate. Coating 1 is mainly composed of NiAl and the solid solution γ-(Fe,Ni) phases. Coating 2 contains of NiAl, Ni₃Al and γ-(Fe,Ni). Coating 3 is mainly composed of Ni₃Al, γ-(Fe,Ni) and NiAl. Coating 3 has excellent wear-resistance property owing to high hardness and low friction coefficient. Ni3Al phase has great influence on wear-resistance property of coating 3. The main wear mechanism of coating 1 is multi-plastic deformation wear and adhesion wear. Grain abrasion is the main wear mechanism of coating 3. The main wear mechanism of coating 2 is grain abrasion and partly adhesive wear.     

Thermal sprayed stainless steel/carbon nanotube composite coatings

Stainless steel/carbon nanotube (SS/CNT) composite coating was prepared by thermal spray from the feedstock powder synthesized by chemical vapor deposition at a synthesis temperature and time of 800 °C and 120 min under ethanol atmosphere. Microstructural investigation by TEM and SEM revealed that grown CNTs covering the surface of stainless steel particles were multi-walled type with an average diameter of about 44 nm. Microstructures of pure stainless steel and SS/CNT composite coatings similarly showed splat characteristic and lamellar structure. Incorporation of CNTs was clearly observed in the composite coating. Hardness of SS/CNT composite coating (480 ± 36 HV_0.3) was higher than that of pure stainless steel coating (303 ± 33 HV_0.3). Coefficient of friction of the SS/CNT coating was almost 3 times lower than that of stainless steel coating which resulted in reduction of sliding wear rate of nearly 2 times. This research thus demonstrated a new composite coating with better wear resistive performance compared to a coating deposited by commercially available stainless steel powder.     

等离子熔覆TiC/Fe-Cr金属陶瓷复合涂层

以钛铁粉、高碳铬铁粉、硼铁粉、硅铁粉等为原料,利用等离子熔覆技术在Q235钢表面原位反应合成了与基材冶金结合Ti/Fe-Cr金属陶瓷复合涂层.利用SEM,XRD和EDS等分析了涂层的显微组织,并在室温于滑动磨损条件下测试了该涂层的耐磨性能.结果表明,涂层组织由TiC相、初生相Cr7C3、共晶(Cr,Fe)7C3和奥氏体...     

Microstructure and sliding wear behavior of nanostructured Ni60-TiB2 composite coating sprayed by HVOF technique

A nanostructured Ni60-TiB₂ composite coating (Ni60 is a brand of Ni-based self-fluxing alloy with a hardness of HRC60) was sprayed on steel substrate by high velocity oxy-fuel (HVOF) process using high energy ball milled powders. Its sliding wear resistance at room-temperature was evaluated by ball-on-disc testing. For comparison, conventional Ni60-TiB₂ composite coating was prepared by HVOF using mechanically mixed Ni60 and TiB₂ powders and tested under the same conditions. The results show that the nanostructured composite coating has excellent mechanical properties and sliding wear resistance due to the microstructural homogenization and the well preserved nanostructure characteristic of the ball milled powders. Adhesive and abrasive wears are found to be responsible for the wear down mechanisms of the nanostructured Ni60-TiB₂ composite coating.     

钛合金表面氩弧熔覆原位合成TiB2-TiN涂层组织及耐磨性能

以BN和Ni60A合金粉末为熔覆材料,采用氩弧熔覆技术在TCA合金表面原位合成TiB2-TiN增强颗粒耐磨涂层．利用x射线衍射仪、扫描电子显微镜和摩擦磨损试验机对熔覆层的组织和性能进行分析测试．结果表明,复合涂层的显微组织沿层深方向分为熔覆区、结合区和热影响区;熔覆层与基体呈良好冶金结合,TiB2-TiN颗粒弥散分布,...     

Microstructure and dry sliding wear behavior of Fe2TiSi /γ-Fe/Ti5Si3 composite coating fabricated by plasma transferred arc cladding process

Wear resistant Fe₂TiSi reinforced composite coating with a microstructure consisting of fine Fe₂TiSi primary dendrites uniformly distributed in the super fine γ-Fe/Ti₅Si₃ eutectic matrix was in situ fabricated on a substrate of 0.20%C plain low carbon steel substrate by the plasma transferred arc (PTA) cladding process using Fe-Ti-Si-Cr powders blend as the precursor material. Microstructure of the coating was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray energy dispersive spectrometer (EDS). Microhardness along the depth direction of the PTA clad Fe₂TiSi/γ-Fe/Ti₅Si₃ multi-phase composite coating was measured. Room temperature dry sliding wear resistance of the coating was tested. Results showed that the PTA clad Fe₂TiSi/γ-Fe/Ti₅Si₃ composite coating had high and almost uniform hardness distribution along the depth direction of the coating. Under dry sliding wear conditions at an ambient temperature, the PTA clad Fe₂TiSi/γ-Fe/Ti₅Si₃ composite coating exhibited excellent abrasive and adhesive wear resistance.     

In Situ TiC-Reinforced Ni-Based Composite Coating Prepared by Flame Spraying Using Sucrose as the Source of Carbon

A Ni-Ti-C composite powder for Reactive Thermal Spraying is made by heating a mixture of titanium, nickel, and sucrose to carbonize the sucrose, which is used as the source of carbon. The carbon obtained by pyrolysis of sucrose is a reactive constituent as well as the binder in the composite powder. The titanium and nickel particles are bound by the carbon to form granules of the composite powder. This powder feedstock was used to prepare in situ TiC-reinforced Ni-based composite coating by oxyacetylene flame spraying. The TiC-Ni composite coating is made of TiC, Ni, and some Ni₃Ti. In the coating, a mass of fine TiC particles is uniformly distributed within the metallic matrix. The microhardness and surface hardness of the coating are, respectively, 1433 HV_0.2kg and 62 ± 6 (HR30N). The wear resistance is much better for the TiC-Ni composite coating than for the substrate and Ni60 coating.     

微米WC增强Ni60合金高频感应熔覆涂层耐磨性能

采用高频感应熔覆方法在Q235低碳钢基体上制备了不同含量的微米WC增强Ni60A合金复合涂层.用MLS-225型湿砂橡胶轮磨粒磨损试验机评价了涂层的耐磨性能,利用SEM,XRD观察并分析了涂层的显微组织和磨损表面形貌.结果表明,在相同试验条件下,涂层的硬度和耐磨性随WC含量的增加而提高,当WC含量少于30%时,WC分布不均匀,主要集中于涂层的中部,涂层中Cr7C3相以粗大的六方状和长条状存在,不利于涂层耐磨性的提高;当WC含量达到50%时,Ni基合金中加入WC的含量达到了合适比例,耐磨性最佳,相对耐磨性为Ni60A涂层的6.5倍;当WC含量达到60%时,涂层的硬度最高,但出现了较多的孔洞,大量未熔的WC颗粒在磨粒的反复作用下剥落形成了大的剥落坑,导致耐磨性下降.涂层与基体实现了冶金结合,涂层的磨损机制主要为轻微的塑性切削和硬质相的脆性剥落.     

等离子喷涂 NiCr-Cr3C2基复合自润滑涂层的组织及摩擦学性能

将NiCr-Cr3C2复合粉和Ni包MoS2粉按不同比例混合,制成三种喷涂粉末,采用等离子喷涂技术在304不锈钢表面制备复合自润滑涂层,并对涂层的物相组成、显微组织及摩擦磨损性能进行了研究。结果表明:三种涂层的物相组成相同,主相均为Cr7C3,Ni和MoS2;涂层与基体的结合为机械结合,孔隙率较低,表面有少量微裂纹;喷涂粉末中的Ni包MoS2粉偏少或偏多都会导致涂层的摩擦磨损性能变坏,Ni包MoS2粉质量分数为30%时,涂层的摩擦系数及磨损率最低,分别约为0.36和3.3×10-4mg/s。     

Effect of power on microstructure and properties of laser cladding NiCrBSi composite coating

A laser clad NiCrBSi composite coating was fabricated on the surface of 42CrMo steel using 6?kW fibre laser. The morphology and composition of the composite coating formed under different powers were studied using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction spectroscopy. The microhardness and wear resistance were measured with a MICROMET-5103 digital microhardness tester and a MM-200 ring-block wear testing machine, respectively. The results showed that the cladding layer and the substrate have good metallurgical bonding. The microstructure nearing the fusion line is a columnar grain and that of the cladding layer is mainly a cellular grain. The main phases of the laser cladding layer are γ-Ni, (Fe,Ni), M₇C₃, M₂₃C₆ and CrB. The dilution rate of the laser cladding layer increased with the increase of laser power. The microhardness of the cladding layers decreased with the increase of laser power, and wear resistance of the cladding layer first increased and then decreased with the increase of laser power. When the laser power was 2000?W, the wear resistance of the composite coating was at its highest.     

氩弧熔敷原位自生TiCp/Ni60A复合材料组织和耐磨性

利用氩弧熔敷技术在16Mn钢表面原位合成TiC增强Ni基复合材料耐磨涂层.采用XRD、SEM等手段分析涂层的组织,测试涂层的室温干滑动磨损性能.结果表明:其室温干滑动磨损机制为显微切削磨损,熔敷层与基体呈冶金结合,TiC颗粒均弥散分布于熔敷层中.涂层有较高的硬度,在室温干滑动磨损试验条件下具有优异的耐磨性.     

Tribological behavior and mechanism of NiCrBSi–Y2O3 composite coatings

The NiCrBSi–Y₂O₃ composite coatings were prepared on the surface of 45 carbon steel by plasma spray, the microstructure and tribological properties of the coatings were investigated. The results show that the NiCrBSi–Y₂O₃ composite coatings are mainly composed of γ-Ni, CrB, Cr₇C₃ and Y₂O₃. With addition of Y₂O₃, hard phases such as CrB, Cr₇C₃ emerge in composite coating, and the density of the composite coatings also increases. The NiCrBSi–0.5Y₂O₃ composite coating presents excellent tribological properties. Its friction coefficient is 0.175, which is about 37% of that of the pure NiCrBSi coating. The mass wear loss is 1.2 mg, which is reduced by 43% compared with the pure NiCrBSi coating. When the loads are 6–10 N, the NiCrBSi–0.5Y₂O₃ composite coating suffers from slight wear and the wear mechanisms are mainly adhesive wear accompany with slight micro-cutting wear and micro-fracture wear. As the load increases to 12 N, the wear mechanisms are adhesive wear and severe micro-cutting wear.     

纳米CeO2对铁基合金喷焊层组织和耐磨性的影响

采用等离子弧喷焊技术在Q235钢表面喷焊含纳米CeO2的铁基自熔性粉末。对喷焊层进行了显微组织、硬度和耐磨损性能的测试。结果表明,添加和未添加纳米CeO2的铁基合金喷焊层的主要组成相均为γ-（Fe,Ni）和（Cr,Fe）7C3,添加5.0%纳米CeO2的喷焊层中出现了（Cr,Fe）3C2相。此外,加入适量纳米CeO2可细化喷焊层的显微组织,提高喷焊层的硬度和耐磨性,磨损机制由黏着磨损转变为磨粒磨损。     

Microstructure and Sliding Wear Performance of Plasma-Sprayed TiB2-Ni Coating Deposited from Agglomerated and Sintered Powder

This work is aimed at developing a route for the deposition of TiB₂-Ni cermet coating. The feedstock was firstly prepared by agglomeration and sintering, which was subsequently subjected to plasma spraying. The microstructures and the phase composition of the powder, as well as the sprayed coating were analyzed by scanning electron microscopy and x-ray diffraction. The microhardness (Hv) and the fracture toughness (K _IC) of the coating were evaluated. A sliding wear test was also performed on the sprayed coating by SRV^® tribo-tester using GCr15 steel as a counterpart. The results showed that the phase of sprayed TiB₂-Ni coatings consisted of TiB₂, Ni, and Ni₂₀Ti₃B₆, whose amount varied depending on the powder calcination temperature and the TiB₂ content in the powder. Both the hardness and the fracture toughness of the coating were also changed with different powders. The Ni₂₀Ti₃B₆ brittle phase was the main factor affecting the fracture toughness of coating, which also had detrimental effect on the sliding wear performance. The 60TiB₂-40Ni coating deposited from the powder calcined at 1250 °C had better sliding wear performance as it presented more dense structure, higher TiB₂ content and less retained Ni₂₀Ti₃B₆ phase in the coating.     

Preparation and wear performance of NiCr/Cr3C2-NiCr/hBN plasma sprayed composite coating

NiCr clad hexagonal BN powder (NiCr/hBN) was added to NiCr/Cr₃C₂ feedstock to improve the tribological properties of chromium carbide nichrome coating. The microstructure, flowability and apparent density of the composite powder, as well as the structure and mechanical properties of the plasma sprayed coating were characterized. The friction and wear behavior of the NiCr/Cr₃C₂-NiCr/hBN coating from ambient temperature up to 800 °C was evaluated on a ball-on-disk wear tester and compared with that of NiCr/Cr₃C₂ coating and NiCr/Cr₃C₂-NiCr/BaF₂·CaF₂ coating. The results show that NiCr cladding can reduce the decarburization of Cr₃C₂ and oxidation of hBN during the thermal spray. The main wear mechanisms of the NiCr/Cr₃C₂-NiCr/hBN composite coating are ploughing and adhesive wear. Layered hexagonal BN particle reduce the direct contact and severe adhesion between friction pairs, thus decreasing the friction coefficient. The NiCr/Cr₃C₂-NiCr/hBN composite coating shows a promising application in the high temperature environment with the request of both wear resistance and friction reduction.     

TIG熔覆原位自生TiC-TiB2/Fe复合涂层

利用氩弧作为热源,以G302铁基合金粉、FeTi70粉和B₄C粉作为原料粉末,在Q235表面原位生成TiC-TiB₂增强的铁基复合涂层. 采用一系列的分析测试方法对涂层进行了表征,结果表明,氩弧熔覆过程冶金反应充分,熔覆层中生成了TiC,TiB₂和M₇C₃等硬质增强相;熔覆层组织呈现出由母材界面到熔覆层表面硬质相逐渐增多的梯度分布特征. 增加FeTi70和B₄C粉末比例提高了熔覆层硬度,质量比为G302:FeTi70:B₄C=6:3:1时,试样最大硬度达到976 HV0.1,是母材硬度的5倍左右. 在与GCr15钢对磨时,熔覆试样磨损量仅为Q235钢的1/30左右,熔覆层磨损表面基本无塑性变形痕迹,涂层中坚硬的TiC,TiB₂陶瓷相起到阻磨作用.     

In situ nanostructured ceramic matrix composite coating prepared by reactive plasma spraying micro-sized Al-Fe2O3 composite powders

In situ nanostructured ceramic matrix composite coating was prepared by reactive plasma spraying micro-sized Al-Fe₂O₃ composite powders. The microstructure of the composite coating was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. The results indicated that the composite coating exhibited dense and crack-free microstructure with a number of spherical α-Fe and γ-Al₂O₃ nano-grains embedded within equiaxed and columnar FeAl₂O₄ nano-grains matrix. The composite coating showed markedly higher toughness and wear resistance than the conventional Al₂O₃ coating.