等离子喷涂WC-12Co/NiCrAl复合涂层的摩擦磨损特性

以NiCrAl涂层为粘结层,用等离子喷涂工艺在TC4钛合金表面制备了WC-12Co/NiCrAl复合涂层。通过扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和显微硬度仪等手段分析了涂层微观形貌、化学成分和显微硬度,并用磨损试验考察了WC-12Co/NiCrAl复合涂层的摩擦磨损特性。结果表明:WC-12Co涂层表面未熔颗粒较多,涂层截面孔隙率为10.2%;WC发生部分分解,出现W2C、Co6W6C等新相;涂层与基体结合界面为机械结合+局部微冶金结合方式;显微硬度为双态Weibull分布,呈现不同位置结构的差异化。WC-12Co涂层表现出良好的减摩及耐磨性能,同载荷下摩擦因数低于基体,磨损失重为基体的1/10,磨粒磨损是其主要磨损机制。     

W1813N无磁不锈钢表面激光熔覆Ni60与WC-12Co/Ni25涂层的组织结构和磨损行为（英文）

利用激光熔覆技术在W1813N无磁性不锈钢表面分别制备高硬度镍基自熔性合金Ni60(60HRC)涂层和低硬度Ni25基WC-12Co复合涂层。利用扫描电子显微镜(SEM)、能谱(EDS)、X射线衍射仪(XRD)和台阶仪,分析激光熔覆制备Ni60涂层和WC-12Co/Ni25复合涂层的显微组织、相组成和磨损行为。利用显微硬度、摩擦系数、磨痕轮廓对比2种涂层的耐磨性和磨损机制。结果表明,Ni60涂层显微组织主要为树枝晶和等轴晶,且Cr23C6,Cr2B等强化相弥散分布在γ-Ni和Fe Ni固溶体晶界;而WC-12Co/Ni25复合涂层中WC-12Co颗粒弥散镶嵌于低硬度Ni25基质,复合涂层中WC-12Co颗粒体积分数达到32.5 vol%。复合涂层中最大和最小显微硬度差异达到6480MPa。尽管2种涂层的摩擦系数相近,但复合涂层的磨损体积仅为Ni60涂层的10%,Ni60涂层表面的磨痕特征为犁沟状和塑性粘附,复合涂层磨痕表面为WC碎屑和塑性粘附,因此Ni60涂层的磨损机制为磨粒磨损和粘着磨损,而复合涂层磨损机制为粘着磨损。以上结果表明WC-12Co/Ni25复合涂层具有更好的耐磨性。     

W1813N无磁不锈钢表面激光熔覆Ni60与WC-12Co/Ni25涂层的组织结构和磨损行为

利用激光熔覆技术分别在W1813N无磁性不锈钢表面制备高硬度镍基自熔性合金Ni60（60HRC）涂层和低硬度Ni25基WC-12Co复合涂层。利用扫描电子显微镜（SEM）、能谱（EDS）、X射线衍射仪（XRD）和台阶仪,分析激光熔覆制备Ni60涂层和WC-12Co/Ni25复合涂层的显微组织、相组成和磨损行为。利用显微硬度、摩擦系数、磨痕轮廓对比两种涂层的耐磨性和磨损机制。结果表明,Ni60涂层显微组织主要为树枝晶和等轴晶,且Cr23C6, Cr2B等强化相弥散分布在?-Ni和FeNi固溶体晶界;而WC-12Co/Ni25复合涂层中WC-12Co颗粒弥散镶嵌于低硬度Ni25基质,复合涂层中WC-12Co颗粒体积比达到32.5%。复合涂层中最大和最小显微硬度差异达到648 HV。尽管两种涂层的摩擦系数相近,但复合涂层的磨损体积仅为Ni60涂层的10%,Ni60涂层表面的磨痕特征为犁沟状和塑性粘附,复合涂层磨痕表面为WC碎屑和塑性粘附,因此Ni60涂层的磨损失效机制为磨粒磨损和粘着磨损,而复合涂层磨损机制为粘着磨损,以上结果表明WC-12Co/Ni25复合涂层具有更好的耐磨性。     

热处理对等离子喷涂WC-12Co涂层性能的影响

为了提高等离子喷涂WC-12Co涂层的性能,分别对其进行了500、650、800和950℃保温60 min的真空热处理。利用威布尔统计方法对涂层的显微硬度进行分析,利用X射线衍射仪(XRD)、扫描电镜(SEM)和能谱仪(EDS)对热处理前后WC-12Co涂层组织结构进行表征,采用自制的干砂型常温冲刷磨损试验机对WC-12Co涂层热处理前后的抗冲蚀磨损性能进行探讨。结果表明:热处理温度为950℃时,涂层中出现大量Co_6W_6C相,在距离涂层表面0～100μm左右的区域内,涂层较为疏松,涂层显微硬度较低且变化较大,在距离涂层表面100～300μm的区域内涂层硬度趋于稳定且较高,同时,涂层的冲蚀磨损量最好,为0.1124 mg/mm~2,较喷涂态WC-12Co涂层的冲蚀磨损量减少41.88%。当热处理温度为800℃时,weibull模量和特征显微硬度最大,分别为11.8426 HV和1411.3 HV,涂层显微硬度的分散性低、可靠性高,涂层质量相对较为稳定。随着真空热处理温度升高,涂层的主要组成相由WC、W_2C转变为Co_3W_3C和Co_6W_6C。真空热处理后,涂层中各元素都发生了不同程度的扩散,其中Al元素扩散程度最大。     

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。     

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。     

HVOF热喷WC-12Co和Ni60涂层在不同攻角下的固体粒子冲蚀行为

目的 解决输气管线弯头冲蚀损伤而导致的刺漏问题。方法 采用超音速火焰喷涂（HVOF）方法在20#钢基材上分别制备WC-12Co和Ni60涂层。采用显微硬度计测试基材及涂层截面显微硬度。采用X射线衍射仪（XRD）分析涂层表面成分。采用自制喷射式气固冲蚀试验机开展30°、50°、90°3种攻角下固体粒子冲蚀（SPE）试验。采用扫描电子显微镜（SEM）观察SPE试验前后表面和截面的微观形貌,开展基材和2种涂层的SPE机理及冲蚀速率研究。结果 在30°攻角下,SPE机理以犁削为主,冲蚀速率受表面硬度的影响较大,20#钢冲蚀速率最大,而WC-12Co涂层的冲蚀速率最小;在50°攻角下,SPE机理为犁削和多冲疲劳混合机理,20#钢的冲蚀速率仍然最大,Ni60涂层和WC-12Co涂层的冲蚀速率相当,均较小;在90°攻角下,冲蚀机理以多冲疲劳损伤为主,WC-12Co涂层的缺陷较少,界面无裂纹,冲蚀速率最小,而Ni60涂层界面处存在裂纹,内部缺陷较多,抗疲劳性能差,冲蚀速率最高。结论 WC-12Co涂层在3种不同攻角下都表现出优异的抗冲蚀性能,为提升输气管线弯头抗冲蚀损伤提供了有力的保障。     

超音速火焰喷涂纳米结构WC-12Co涂层耐泥沙冲蚀性能研究

采用超音速火焰喷涂(HVOF)分别制备了纳米结构、双峰结构及微米结构WC-12Co金属陶瓷复合涂层,比较了不同结构WC-12Co涂层的组织结构及显微硬度,进行了不同结构WC-12Co涂层和Ni60喷熔层的泥浆冲蚀磨损试验,并探讨了它们的泥浆冲蚀机理.结果表明:采用超音速火焰喷涂制备的纳米结构及双峰结构WC-12Co涂层结构致密,涂层显微硬度明显高于微米结构WC-12Co涂层;与微米结构WC-12Co涂层相比,纳米结构和双峰结构WC-12Co涂层具有更优良的抗泥浆冲蚀性能,其耐泥浆冲蚀性能分别提高了50%及20%以上.     

超音速火焰喷涂碳化钨-钴涂层磨粒磨损行为

采用超音速火焰喷涂工艺在16Mn钢上制备了WC-12Co涂层,并测试了该涂层的力学性能特别是其抗磨粒磨损性能。结果表明:WC-12Co涂层的主相为碳化钨,显微硬度为(1341.0±134.3)HV,孔隙率为0.21%±0.04%。该涂层的磨损率随着磨粒硬度、磨粒粒度和加载载荷的增加而增加。当磨粒的硬度低于涂层硬度时,涂层的磨损机制以磨耗磨损为主,磨损率低;当磨粒的硬度超过涂层的硬度时,涂层的磨损以微切削为主,磨损率高。另外,WC-12Co涂层的耐磨性相对于16Mn钢也是随着磨粒的硬度变化而变化。     

Ti-6Al-4V表面电子束熔覆(Ti,W)C1-x复合涂层的形成及摩擦性能

通过高能电子束熔覆技术,利用WC-10Co粉末在Ti-6Al-4V (TC4)合金表面制备了(Ti, W)C_(1-x)复合涂层。采用SEM、EPMA和XRD等手段对不同熔覆电流下复合涂层的显微组织和相组成进行了分析,讨论了各相的形成机理;采用显微硬度计和球盘摩擦实验设备对复合涂层的显微硬度和摩擦性能进行分析,讨论了不同熔覆电流下复合涂层的摩擦机理。结果表明,3种复合涂层中WC粉末均全部分解,涂层由α-Ti、β-Ti、树枝状和块状(Ti, W)C_(1-x)及少量W组成。复合涂层厚度为400～600μm,涂层与基体结合性良好。与基体相比,(Ti, W)C_(1-x)复合涂层的平均硬度和耐磨性提高2～3倍且随熔覆电流增加而降低,在熔覆电流为12 mA时,表面显微硬度最高为860 HV;熔覆电流为12和15 m A时摩擦机理分别为轻微磨粒磨损和严重的磨粒磨损,而18 mA时还伴随着少量疲劳磨损。     

喷涂距离对等离子喷涂WC-12Co涂层抗冲蚀磨损性能的影响

为提高WC-12Co涂层抗冲蚀磨损性能,在Q235钢基体上采用大气等离子喷涂(APS)方法制备WC-12Co涂层,研究了喷涂距离对粒子温度与速度、涂层组织结构、力学性能及抗冲蚀磨损性能的影响。结果表明:喷涂距离对涂层质量影响较为明显,喷涂距离为130 mm时涂层质量较好,粒子速度与温度达到较好的配合,涂层抗冲蚀磨损能力较强。喷涂距离为120 mm与140 mm时涂层抗冲蚀磨损能力较差。550μm(30目)沙粒直径对涂层冲蚀磨损量大,沙粒速度为15.68 m/s比13.33 m/s沙粒速度冲蚀磨损量大;冲蚀角为60°时冲蚀磨损量最大,30°冲蚀磨损量最小。     

爆炸喷涂WC-12Co/MoS_2复合涂层的摩擦磨损性能

为进一步提高爆炸喷涂WC-12Co涂层的耐磨性,在WC-12Co合金粉末中添加不同比例的MoS2粉末,利用爆炸喷涂技术在Q235钢表面制备了系列WC-12Co/MoS2复合涂层.采用金相显微镜、扫描电子显微镜、X射线衍射仪、显微硬度计及摩擦磨损试验机对WC-12Co/MoS2复合涂层的微观组织形貌、结构、显微硬度、摩擦磨损性能进行了研究.结果表明,MoS2均匀的分布于复合涂层中,当MoS2含量为2%时,复合涂层的硬度、致密度变化不大,但摩擦系数和磨损率大幅度下降,分别为WC-12Co涂层的50%和36%.随着MoS2含量的增加,复合涂层的摩擦系数和磨损率均呈上升趋势.     

Microstructures and erosion resistance of plasma-sprayed WCp/NiCrBSi composite coatings

WCp/NiCrBSi composite coatings have been deposited by plasma spraying with the mixed powders of WC-12Ni and NiCrBSi. The coatings consist mainly of WC, γ-Ni, Ni3B, CrB, Cr2B, M7C3, M23C6 and W2C phases. The W2C content increases with increasing WC mass fraction in the powders. The porosity and microhardness of the coatings are related to the coating WC content. The excessive WC results in decreasing the microhardncss due to increasing the porosity. The WCp/ NiCrBSi coating with 35 % WC mass fraction powder has more excellent erosion resistance. With an increase of impact angles from 15°to 90°the erosion rate of the coating increases, the erosion rate at 15°impact angle being approximately two times lower than that at 90°impact angle. Based on the wear morphology of the coatings at different impact angles, the wear mechanisms were discussed.     

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.     

Influence of Rare Earth on the High-Temperature Sliding Wear Behavior of WC-12Co Coating Prepared by HVOF Spraying

In this work, WC-12Co coatings were prepared by high-velocity oxygen fuel spraying (HVOF) technology. The high-temperature sliding wear tests at 450, 550 and 650 °C were conducted on a pin-on-disk tribometer, and effects of CeO₂ on the high-temperature wear behavior were investigated. The results showed that CeO₂-modified WC-12Co coating possessed better sliding wear resistance than that of conventional WC-12Co coating at the tested temperatures. The maximum microhardness value of 1333 ± 25HV_0.5 was available at the temperature of 550 °C for CeO₂-modified WC-12Co coating worn track. The oxides formed on the worn surface played a significant role on the wear behavior. W₂C, Co₃O₄ and ratio of CoWO₄/WO₃ dominated the wear behavior of the coating at 450, 550 and 650 °C, respectively.     

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.     

HVOF喷涂WC-10Co-4Cr涂层的砂浆冲蚀行为

以2种不同的HVOF喷涂系统和3种商用粉末在0Cr13Ni5Mo基材上喷涂6种WC-10Co-4Cr涂层,用自行研制的料浆罐冲蚀设备对涂层和基材的砂浆冲蚀行为进行了研究,分析了显微结构和显微硬度对涂层冲蚀性能的影响及涂层冲蚀后的表面形貌.结果表明,在文中试验范围内涂层和基材的冲蚀失重均随冲蚀时间线性增加;各攻角下,WC-10Co-4Cr涂层的耐冲蚀性远远优于0Cr13Ni5Mo不锈钢;除了分层和裂纹明显的涂层,HVOF热喷WC-10Co-4Cr涂层的冲蚀失重表现出对攻角不敏感的特征.涂层的冲蚀机制为粘结相的微切削和涂层片状剥落,低攻角下的剥落坑面积大而浅,高攻角时面积小而深,片状剥落的程度随涂层气孔率的增加而增加.     

铸钢轧辊亚微米WC-4Co电火花沉积涂层高温性能

用新型电火花沉积设备,把WC-4Co陶瓷硬质合金材料沉积在铸钢轧辊材料上,制备了电火花沉积合金涂层,用SEM和XRD等技术研究了沉积层在300 ℃的高温耐磨性和800 ℃高温氧化100 h后氧化膜形貌、组织结构和高温抗氧化性能.结果表明,沉积层厚度为20～30 μm,沉积层由Fe3W3C,Co3W3C,Si2W和W2C等物相组成.300 ℃高温条件下沉积层的耐磨性比基体提高了3.4倍,300 ℃高温条件下沉积层的磨损机理主要是粘着磨损、疲劳磨损、氧化磨损和磨粒磨损的综合作用.800 ℃高温条件下沉积层氧化100 h后的氧化膜的厚度约为10～20 μm;氧化膜主要由Fe3O4,Fe2O3,W20O58和Si物相组成;800 ℃高温下沉积层抗氧化性能比基体的抗氧化性能提高了2.6倍.细小弥散分布的硬质相提高了沉积层的抗高温磨损性能和抗高温氧化性能.