WC粒度对WC-10Co-4Cr复合粉末特性及其涂层性能的影响

利用超音速火焰喷涂技术制备了微米结构、亚微米结构、纳米结构以及多尺度结构的WC-10Co-4Cr涂层,研究了WC粒度对WC-10Co-4Cr复合粉末表面和内部结构及其涂层的孔隙率、硬度分布和断裂韧性的影响规律.结果表明:采用团聚烧结法制备的热喷涂粉末球形度较高,表面呈疏松多孔状,主要物相为WC、Co和Co3W3C;利用...     

超音速火焰喷涂微纳米WC-CoCr涂层的性能与空蚀行为

采用超音速火焰喷涂(HVOF)制备普通微米和微纳米WC-10Co4Cr金属陶瓷涂层,使用光学显微镜、扫描电镜和X射线衍射仪方法分析涂层的组织结构;测量涂层的显微硬度、孔隙率及开裂韧性;采用超声振动空蚀装置在淡水介质中研究WC-10Co4Cr涂层的抗空蚀性能和空蚀行为,并探讨涂层的空蚀机理。结果表明:采用HVOF制备的微纳米WC-10Co4Cr涂层主要由WC相、非晶Co Cr相和微量的W2C相组成,涂层中WC未产生明显的脱碳现象;HVOF工艺制备的微纳米WC-10Co4Cr涂层的力学性能和抗空蚀性能明显优于普通WC-10Co4Cr涂层的,在稳定空蚀阶段淡水中微纳米涂层的抗空蚀性能比普通涂层的提高大约1倍。     

WC-Co复合粉末的原位合成及于硬质合金涂层制备中的应用

目的为解决超细/纳米WC-Co热喷涂时易于脱碳等瓶颈问题,制备具有高的硬度、断裂韧性、耐磨性和表面质量等优异综合性能的超细及纳米结构硬质合金涂层,并推广其在工业领域中的应用。方法以原位合成技术批量制备的超细/纳米WC-Co复合粉末为原料,利用团聚造粒技术制备得到具有高球形度和致密性,并保持原有超细/纳米结构的喷涂喂料粉末,利用超音速火焰喷涂工艺制备低脱碳、高致密的超细结构WC基涂层。结果降低喂料粉末孔隙度可有效减少涂层中W2C等脱碳相的含量,在优化工艺下制备的超细结构WC基涂层的硬度达到1450HV0.3以上,韧性相对于常规微米结构涂层提高40%以上,在两种载荷和磨料条件下均表现出更高的耐磨性。结论利用原位反应技术批量合成的超细/纳米WC-Co复合粉制备的硬质合金涂层具有优良的综合性能,可应用于对涂层的硬度、耐磨性、强韧性配合和表面质量有较高要求的工况。     

表面喷涂对不锈钢零件耐磨性能的影响

在不锈钢表面采用超音速火焰喷涂了WC-10Co-4Cr涂层,并对喷涂粉末和涂层的显微形貌、物相组成进行了表征,研究了基体与涂层的耐磨性能。结果表明,不锈钢表面涂层与基体以机械结合为主、冶金结合为辅,基体与涂层间过渡良好,未发现气孔或者微裂纹缺陷;原始喷涂粉末的物相组成为WC、Co和少量Co3W3C相,经过超音速火焰喷涂处理后,涂层的物相组成为WC、Co6W6C和W2C相;经过超音速火焰喷涂处理后,涂层的摩擦磨损性能明显优于不锈钢基体,这主要与致密的涂层硬度较高、抗摩擦磨损能力更强有关。     

再生WC-Co复合粉及高耐磨性硬质合金涂层的制备

以WC-6Co废旧硬质合金块体和Co_3O_4粉末为原料,采用氧化-还原碳化法制备再生WC-12Co复合粉,将复合粉经过造粒和热处理制备再生热喷涂喂料,进而采用超音速火焰喷涂(HVOF)制备再生WC-Co硬质合金涂层,比较再生硬质合金涂层和商业购买热喷涂喂料制备涂层的显微组织、耐磨性及其机制。结果表明:当配碳量为16.70%(质量分数)时,再生复合粉的碳含量适中;制备的再生热喷涂喂料由WC和Co相组成,热喷喂料球形度好,粒径分布均匀,平均粒径为23μm;再生WC-12Co硬质合金涂层的结构致密,WC晶粒尺寸分布均匀。与商业化热喷涂粉制备涂层显微组织和性能相比,再生涂层的磨粒磨损性能明显优于商业喷涂粉制备涂层的,其根本原因是两者的磨损机制不同。     

含MoS2的超音速喷涂WC-10Co-4Cr复合涂层摩擦性能研究

利用超音速火焰喷涂方法,以WC-10Co-4Cr为基体,添加MoS2以制备WC- 10Co-4Cr/MoS2自润滑复合涂层;对比分析了添加不同含量MoS2涂层的微观组织结构和物相;重点进行了摩擦磨损试验,研究润滑相MoS2对超音速喷涂WC涂层摩擦学特性的影响机理.研究结果表明:引入的MoS2一少部分转化成新态,其余则进入WC涂层空隙中,在摩擦过程中形成润滑膜起到润滑作用,并有效地降低了摩擦因数,使摩擦磨损过程中温升降低,有效减少热损伤,提高了涂层的耐磨性能;WC-10Co-4Cr/MoS2复合涂层具有很好的自润滑性,w(MoS2)15％时WC-10Co-4Cr/MoS2复合涂层的摩擦磨损性能最佳.     

复合添加晶粒长大抑制剂对WC-12Co超细晶硬质合金涂层性能的影响

利用真空原位还原碳化反应合成超细WC-12Co复合粉末,通过复合添加不同含量的晶粒长大抑制剂VC和Cr_3C_2,经团聚造粒获得喷涂用复合粉末喂料,采用超音速火焰(HVOF)喷涂系统制备WC-12Co涂层。利用X射线衍射和扫描电镜对涂层的物相、显微组织结构等进行了系统表征,并对涂层耐磨性进行了测试分析。结果表明:WC-12Co涂层中WC晶粒的平均尺寸,随着晶粒长大抑制剂的增加而减小,且抑制剂的添加使涂层的摩擦系数降低;当复合添加抑制剂总含量(质量分数)为1.0%时,WC-12Co涂层的显微硬度(HV_(0.3))达到最大值13 670 MPa,且涂层的磨损速率最低;随抑制剂含量进一步增加,WC-12Co涂层的显微硬度逐渐降低,磨损速率增加,涂层的耐磨性降低。     

机床液压设备表面喷涂WC-10Co4Cr涂层与性能研究

采用超音速火焰喷涂法在机床液压设备表面热喷涂了WC-10Co4Cr涂层,并对涂层显微形貌、物相组成、耐磨性能和耐腐蚀性能进行了测试。结果表明,WC-10Co4Cr涂层的物相组成主要为WC、W_2C、Co Cr和Co相;WC-10Co4Cr涂层较为致密、均匀,孔隙率约为0.75%;WC-10Co4Cr涂层的体积损失量约为基体的1/150,表现出优良的抵抗滑动摩擦磨损能力;虽然电镀硬铬可以提升材料的耐腐蚀性能,但WC-10Co4Cr涂层的耐腐蚀性能更加优越,腐蚀速率约为基体材料的2%。     

HVOF喷涂制备的多尺度WC-10Co4Cr涂层的组织与空蚀行为（英文）

采用超音速火焰(HVOF)喷涂制备了一种新型的由纳米、亚微米、微米WC颗粒和Co Cr合金组成的多尺度WC-10Co4Cr金属陶瓷涂层,对比了双峰和纳米结构WC-10Co4Cr涂层,在分析了涂层组织的基础上,研究了多尺度涂层的孔隙率、显微硬度、开裂韧性和抗空蚀性能,并分析了多尺度WC-10Co4Cr涂层的空蚀行为和机理。结果表明,HVOF喷涂制备的多尺度WC-10Co4Cr涂层具有≤0.32%的孔隙率和高的开裂韧性,涂层中未发现明显的纳米WC脱碳现象。与双峰与纳米结构涂层相比,多尺度WC-10Co4Cr涂层表现出最优异的抗空蚀性能,在淡水中的抗空蚀性能分别比双峰涂层和纳米结构涂层提高了大约28%和34%。多尺度WC-10Co4Cr涂层的优异抗空蚀性能归结于其独特的微纳米结构和优良的性能,能有效阻碍空蚀裂纹的形成和扩展。     

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。     

Microstructure and performance of WC-Co-Cr coating with ultrafine/nanocrystalline structures

The WC-lOCo-4Cr composite powder was synthesized firstly. Then the composite powder was agglomerated to prepare thermal spraying feedstock. The ultrafine/nanostructured WC-lOCo-4Cr coating was prepared by high velocity oxygen fuel thermal spraying. The phase constitution, elemental distribution and microstructure of the coating were characterized by X-ray diffraction and transmission electron microscopy, respectively. The wear resistance and corrosion resistance of the prepared composite coating were tested. The results show that the main phases of the coating include WC, binding phase with partial amorphous structure, with a little W_2C and Co(Cr)coexisting. The distributions of Co and Cr elements from the phase boundary to the eutectic area then to Co zone were analyzed quantitatively. The mechanisms for the formation of the microstructure and effects of Cr on the performance of the composite coating are proposed.     

超细硬质合金晶粒生长抑制剂VC、Cr_3C_2作用机理的研究

本文以液相复合-连续还原碳化方法制备的掺杂有VC和Cr3C2抑制剂的纳米复合WC-10Co粉末为原料,采用真空烧结+低压处理的工艺制备超细WC-10Co硬质合金,运用原子力显微镜(AFM)和场发射扫描电镜(FESEM)确定VC和Cr3C2抑制剂在硬质合金中的分布,讨论其抑制晶粒生长的机理。一部分VC、Cr3C2抑制剂吸附在WC晶粒表面形成30nm～50nm的沉淀物,降低WC晶粒的表面能;一部分VC、Cr3C2溶解在Co相中,降低WC在液相中的溶解度;其余VC、Cr3C2沉积在WC晶界,从而有效地抑制WC晶粒的长大。     

HVOF喷涂纳米结构WC-12Co涂层的组织结构分析

纳米结构WC-12Co涂层的研究目前已受到了广泛重视,对其组织结构及影响因素的研究有利于提高涂层性能.采用HVOF工艺制备了纳米结构、多峰结构及普通微米结构3种WC-12Co金属陶瓷复合涂层,并采用SEM、XRD等对粉末及涂层的显微形貌、组织结构进行了分析;探讨了粉末在喷涂过程中的氧化脱碳机理,并指出了与之相关的影响因素.结果表明:纳米结构WC-12Co涂层结构致密,孔隙率低,与基体结合状态良好;纳米粉末在喷涂过程中比微米粉末氧化失碳严重,并发生了不同的纳米晶粒的长大;纳米粉末在喷涂过程中的氧化脱碳程度不仅与喷涂工艺有关,还在很大程度上取决于粉末本身的结构特性.     

Corrosion behavior of thermal-sprayed WC cermet coatings in SO4 2− environment

A series of the electrochemical and long-term corrosion tests was carried out in a 3.5 wt% Na2SO4 solution on thermal-sprayed WC-17Co and WC-10Co-4Cr cermet coatings in order to examine the effect of composition of binder materials on the corrosion behavior. The results reveal that the overall corrosion resistance of the WC-17Co coating is inferior to that of the WC–Co–Cr coatings due to the corrosion of binder materials which induce WC particles to fall off. CoO and WO3 oxide films form on the surface of WC-17Co coating in Na2SO4 solution electrochemical corrosion process, which will protect the coating in the process of corrosion. Cr2O3 oxide film formed on the WC-10Co-4Cr coating surface has a strong hindered role to corrosion. The corrosion mechanism of WC-17Co coating in Na2SO4 solution is entire corrosion of Co matrix, while it is film-hole corrosion mechanism for WC-10Co-4Cr coating.     

Characteristics of nano particles and their effect on the formation of nanostructures in air plasma spraying WC-17Co coating

WC-17Co nanostructured coating was prepared by means of air plasma spraying technology. Microstructures and compositions of the nano WC-Co powder and coating were analyzed using SEM (Scanning Electron Microscopy), and XRD (X-ray Diffraction), etc. The average grain size of the coating was measured using XRD. The mechanism of nanostructure formation and the properties of the nanostructured coating were investigated. The results show that the size of original particles is about 50-500 nm. Finer sub-particles of 2-5 nm are found to exist in the original particles. These sub-particles can act as crystallization nuclei and make the grains much finer during the plasma spraying process, which is beneficial to the formation of nanostructure in the coating. Both amorphous and nanostructured phases can be identified in the coating. The nanostructured coating is mainly composed of WC, W₂C and some amorphous phases. The nanostructured WC-Co coating has a good mechanical property combination. Nanostructured coating possesses good combination properties of micro-hardness, fracture toughness and bonding strength.     

Effect of VC and NbC additions on microstructure and properties of ultrafine WC-10Co cemented carbides

The nanocomposite WC-Co powders were prepared through planetary ball milling method. Effects of grain growth inhibitor addition and the vacuum sintering parameters on the microstructure and properties of ultrafine WC-10Co cemented carbides were investigated using X-ray diffractometer, scanning electron microscope and mechanical property tester. The results show that VC and NbC additions can refine the WC grains, decrease the volume fraction of Co₃W₃C phase in ultrafine WC-10Co cemented carbides, and increase the hardness and fracture toughness of the base alloys. After sintering for 60 min at 1400 °C, the average grain size and hardness of ultrafine-grained WC-10Co-1VC cemented carbide are 470 nm and HRA 91.5, respectively. The fracture toughness of cemented carbide WC-10Co-1NbC alloy is over 7 MN·m^?3/2.     

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。     

等离子熔覆Fe基/WC-10Co-4Cr涂层的组织与性能研究

目的 制备高强度和高硬度的耐磨性涂层,用于已磨损的机械零件表面,以延长其使用寿命,避免机器因磨损而带来的各种故障。方法 采用等离子熔覆技术在40CrMnMo表面制备WC-10Co-4Cr/Fe300合金复合熔覆层,研究不同质量分数WC-10Co-4Cr对熔覆层组织和性能的影响。利用金相显微镜、超景深光学显微镜、SEM、EDS、XRD对熔覆层的组织形貌进行表征和物相分析,借助数显显微硬度计和销盘式摩擦磨损试验机测试熔覆层的硬度和耐磨性。结果 WC-10Co-4Cr/Fe300合金作为一种复合材料,与基材形成了冶金结合,结合区域无孔洞和裂纹。熔覆层微观结构随着WC-10Co-4Cr含量的增加,逐渐由柱状晶向树枝晶过渡,它主要由Fe₆W₆C、(Cr、Fe)₂₃C₆和WC相组成。熔覆层的平均硬度大致随着WC-10Co-4Cr含量的增加而提高,当WC-10Co-4Cr的质量分数达到20%时,熔覆层的硬度最高(518.5HV0.2),大约是基体硬度的1.7倍。熔覆层的主要摩擦机理为磨粒磨损,随着WC-10Co-...     

A Comparison of Mechanical and Tribological Behavior of Nanostructured and Conventional WC-12Co Detonation-Sprayed Coatings

In the present study, WC-12Co coatings were deposited by detonation-spraying technique using conventional and nanostructured WC-12Co feedstock at four different oxy/fuel ratios (OF ratio). The coatings exhibited the presence of phases like W₂C and W due to the decarburization of the WC phase, and the proportions of these phases were higher in the nano WC-12Co coatings compared with conventional WC-12Co coatings. Coating hardness and fracture toughness were measured. The tribological performance of coatings was examined under dry sand rubber wheel abrasion wear, and solid particle erosion wear conditions. The mechanical and wear properties of coatings were influenced by degree of decarburization and more so in the case of nanostructured WC-Co coatings. The results indicate that the extent of decarburization has a substantial influence on the elastic modulus of the coating which in turn is related to the extent of intersplat cracking of the coating.