电沉积稀土改性陶瓷涂层磨损性能研究

探讨了在电火花加工机床上沉积碳化钛金属陶瓷涂层方法,利用TiC,WC,Mo,N i粉未添加不同比例稀土元素在高压下压制并烧结了试验电极,在45#钢表面沉积了不同稀土含量的TiC陶瓷涂层,并用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、环块式磨损试验机对涂层组成、组织形态进行、硬度及摩擦学性能分别进行了研究,并结合试验结果进行了理论分析。试验结果表明:用电火花放电法可沉积TiC陶瓷涂层,涂层中加入质量分数为0.5%的氧化镧后,涂层的耐磨性能较未加稀土涂层提高了3倍,摩擦因数减少10%,而加入过多的稀土镧氧化物则不利于涂层组织性能及耐磨性能的改善。稀土氧化镧对涂层的组织有改善作用,加入适量的稀土元素使得涂层致密性提高,减少涂层中的缺陷,涂层表面呈多孔结构特性。     

La2O3对电火花沉积TiC4涂层微观结构及抗磨性能的影响

探讨电火花加工方法制作TiC4陶瓷涂层工艺,制作表面改性用电极,分析电极参数及加工工艺参数对涂层性能的影响,在45钢基体上制作了TiC4陶瓷及稀土氧化镧改性的陶瓷涂层.用X射线衍射仪(X-ray diffractometer,XRD)、分析型扫描电镜(Analysis scanning electron microscope,ASEM)对涂层组成、组织形态进行分析,并在HQ-1型摩擦磨损试验机上对涂层摩擦学性能进行研究.结果表明:利用电火花沉积工艺可在钢基体上制作TiC4陶瓷涂层,电极中加入适量氧化镧对涂层组织有改善作用,稀土的加入使得涂层组织缺陷减少,涂层的致密度得到提高;当稀土氧化镧的添加质量分数为0.5%时,涂层的耐磨性能提高了3倍,摩擦因数降低了10%;添加过多的稀土对改善陶瓷涂层性能反而不利,涂层的组织缺陷增加,表面粗糙度也随之增大,耐磨性能降低.     

碳化硼及硅铁稀土激光熔覆层摩擦学性能研究

为考查稀土镧元素对硼的催渗作用及对激光熔覆层性能的影响，用铁粉、碳化硼、硅铁稀土等物质，在45^#钢试块表面熔覆一层高镧高硼激光熔覆层，并在摩擦磨损试验机上考察了熔覆层的摩擦学性能。通过熔覆层表面组织XPS(X射线光电子能谱仪)分析，探讨了在稀土镧元素作用下，熔覆层的组织性能变化及对摩擦副摩擦学性能的影响。试验结果表明：稀土元素加入改善了表层组织结构，避免了熔覆层表面开裂现象的发生，表层硬度及耐磨性能得到了显著改善，硅铁稀土加入量为5％～6％时熔覆层耐磨性能最佳。     

CeO_2对镍基TiC陶瓷涂层微观组织和摩擦学性能的影响

采用W150SA YAG激光焊接机45#钢基材表面熔覆含CeO2的镍基TiC陶瓷涂层,研究添加不同含量CeO2对涂层的微观组织和摩擦学性能的影响.研究结果表明:添加适量CeO2对涂层的微观组织、显微硬度、涂层与基材结合区,以及涂层的摩擦学性具有改善作用;CeO2能减弱熔池中TiC陶瓷相的生长方向性,避免相邻的TiC颗粒桥接生长,细化和球化TiC颗粒,并使之且分布均匀;CeO2能促使TiC硬质相弥散分布,涂层组织趋向均匀化,并减少杂质和气体的不良影响,提高涂层的组织性能;CeO2能促进涂层与基材之间形成合理的成分梯度,得到良好的结合区;CeO2能促进摩擦过程中涂层表面氧化膜的形成并提高氧化膜的热稳定性,减少涂层的大片层状剥落,降低涂层的黏着磨损和磨粒磨损.     

氧化镧改性树脂基复合材料摩擦学性能研究

为克服树脂基制动材料易产生热衰退而失效的问题,在热压成型的树脂基制动摩擦材料加入氧化镧进行改性。通过正交试验方差分析获得摩擦学性能较优的配方,通过X-DM摩擦试验、磨损表面形貌分析等手段探讨氧化镧对材料在不同温度下的摩擦学性能的影响,并探讨其摩擦磨损机制。结果表明:摩擦材料配方组分及质量分数分别为氧化镧21. 6%、酚醛树脂12. 9%、硅酸铝纤维12. 9%、竹纤维2. 6%,其他填料50%时可获得较优的摩擦磨损性能;加入适量的氧化镧不仅能够稳定低温、高温摩擦因数,还能降低磨损率,减少热衰退的产生;在树脂基制动摩擦材料中加入适量的氧化镧后,其磨损形式由磨粒磨损为主转变为黏着磨损为主,且磨损表面出现大面积连续的摩擦膜。     

氧化镧对纳米Al2O3-13TiO2等离子喷涂层的摩擦磨损性能影响

以添加少量氧化镧的团聚纳米Al2O3-13%TiO2粉末为原料,利用等离子喷涂技术制备纳米陶瓷涂层,在MMS-1G型高速摩擦磨损试验机上考察其摩擦磨损性能,并利用扫描电镜和能谱仪表征其磨损表面。结果表明:添加1%氧化镧的涂层具有更低的孔隙率,更高的抗拉结合强度;在高速摩擦磨损试验过程中,氧化镧可起到降低摩擦因数及磨损率的作用,添加1%氧化镧的纳米涂层摩擦磨损性能优良。磨损是由涂层微裂纹扩展导致的涂层剥落引起的,黏着磨损显著。     

模具钢表面Co/TiC熔覆层的组织与高温磨损性能

利用6 kW横流CO2激光器制备了Co50熔覆层和不同成分配比的Co/TiC复合涂层来改善H13模具钢表面的热磨损性能.借助X射线衍射(XRD)、扫描电子显微镜(SEM)、显微硬度计和高温摩擦磨损试验机分析了涂层的结合特征、物相组成和不同温度下的摩擦磨损性能.结果表明,当预置层粉末TiC含量(重量百分比)小于等于20％时,熔覆层与H13钢基材呈良好的冶金结合;随着TiC含量的增加,Co/TiC复合涂层截面平均显微硬度呈上升趋势,但涂层中基体相种类减少:Co+10％TiC涂层由TiCo3、Cr2Ni3和Cr-Ni-Fe-C组成,Co+20％TiC涂层由Cr2Ni3和γ-Co组成,Co+30％TiC涂层为γ-Co固溶体.Co+ 20％ TiC涂层的高温耐磨性比C050涂层显著提高,摩擦系数平稳;700℃时复合涂层的磨损机制主要为氧化磨损和疲劳磨损.结果显示Co+20％TiC涂层具有良好的综合性能.     

阳极PED技术制备活塞环表面陶瓷涂层的研究

在内燃机中,由于摩擦产生的输出功率损失达到20%,可见摩擦磨损是影响内燃机燃油效率的关键因素,其中,活塞环-缸套摩擦副产生的摩擦在内燃机摩擦中占比超过50%,因此,改善活塞环组件的摩擦学性能对提高内燃机性能有着重要的意义。本文对活塞环表面改性、活塞环表面织构、润滑条件等影响活塞环摩擦学性能的因素进行了阐述,着重对利用阳极等离子体电解沉积(PED)技术制备活塞环表面涂层的技术研究进行了介绍,并给出一种利用该技术制备陶瓷涂层的方案供参考。     

CeO2和Y2O3对Ti-Al/WC金属陶瓷复合涂层摩擦学性能的影响

为了改善等离子喷涂涂层表面组织结构性能差和耐磨性能低的问题,以相同质量分数的CeO_2、Y_2O_3作为涂层的添加剂,采用等离子喷涂的方式制备出不同类型的稀土涂层。利用附带有能谱仪(EDS)的扫描电镜(SEM)、X射线衍射仪(XRD)以及摩擦磨损试验机对各涂层表面形貌和组织特征以及耐磨性能进行对比和分析。结果表明:当加入稀土后,特别是同时加入CeO_2和Y_2O_3时,等离子喷涂涂层的材料堆积、孔隙等基本消失,涂层内的残余应力下降38%,且摩擦性能和耐磨性能得到明显的提高;单独加入CeO_2和Y_2O_3后涂层的磨损由严重的黏着磨损转变为黏着磨损和磨粒磨损,同时加入CeO_2和Y_2O_3后涂层仅发生磨粒磨损。     

石墨含量对石墨固体润滑涂层摩擦学性能的影响

利用简便的刷涂法在钢基体表面制备了石墨固体润滑涂层。利用MM-200型摩擦磨损试验机对不同石墨含量的固体润滑涂层进行了详细的摩擦学性能对比试验。结果发现．石墨固体润滑涂层的摩擦学性能与石墨含量之间呈“马鞍形”变化规律，当石墨的质量分数为28％时，固体润滑涂层的减摩、耐磨性能最佳。     

Tribofilm formation and tribological properties of TiC and nanocomposite TiAlC coatings

In a recent work a concept for self lubricating low friction TiC and nanocomposite TiAlC coatings was developed. Here we further investigate the mechanical and tribological properties of these coatings. Under identical deposition conditions, the addition of Al initiates the formation of a nanocomposite consisting of (Ti,Al)C grains in an amorphous carbon matrix. The coefficient of friction is lowered from ～0.2 to below 0.1 in a pin-on-disc test against steel with unaffected coating wear rate. The lower friction is attributed to a more extensive formation of amorphous carbon and graphitisation on both the counter surface and in the coating wear track. The addition of Al also reduces coating hardness, Young's modulus and the residual stress, which can be explained by the weak carbide-forming ability of Al and the formation of a nanocomposite microstructure.     

Experimental examination of the wear behaviour of the VAlN tool coating by strip drawing process

Resistance to wear, and therefore the lifetime of forming tools, can be increased by surface functionalisation using novel, multifunctional coatings. Thereby, the tribological requirements on the coating are an essential factor. Within the scope of the research work presented here, tribological examinations were carried out on a metastable vanadium aluminium nitride (VAlN) tool coating when drawing the high-strength sheet metal material DP 800. It was shown that the wear of the VAlN tool coating can already be determined at stable frictional behaviour (μ?<?0.085). The wear analysis was carried out considering the topography and change in hardness of the tool surface during the drawing path of 110,000?mm under a contact stress of 150?MPa.     

镍基合金喷熔层摩擦学行为与机制的研究

采用热喷熔工艺制备了两种镍基合金喷熔层,并选用高锰钢、不锈钢作为对比材料,研究了镍基合金喷熔层的摩擦磨损性能。研究结果表明：镍基合金喷熔层具有良好的耐磨损性能和较低的摩擦系数。镍含量对喷熔层的摩擦学性能有显著影响,高镍含量的镍基合金,其耐磨性能明显优于低镍含量的镍基合金。在低速轻载条件下,镍基合金喷熔层的磨损机理为微观犁削;高速重载时,表现为粘着磨损和磨料磨损,其中高镍含量的喷熔层表面形成了致密的转移膜,有效地降低了磨损率。     

Wear Behavior of Ceramic Powder and Solid Lubricant Cladding on Carbon Steel Surface

Thick composite coatings of carbides on a metal matrix are ideal for use in components that are subjected to severe abrasive wear. It is a metal matrix composite (MMC) that is reinforced by an appropriate ceramic phase, a solid lubricant coating to reduce friction and to protect the opposing surface. This study tested the wear behavior of a carbon steel surface after cladding by a gas tungsten arc welding (GTAW) method to enhance wear resistance. The microstructures, chemical compositions, and wear characteristics of the cladded surfaces were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The coating was uniform, continuous, and almost defect-free, and particles were evenly distributed throughout the cladding layer. The results of wear tests indicate that the friction coefficient of the TiC coating is lower than that of AISI 1020 carbon steel. Thus, the wear depth of the TiC coating is only one tenth of that exhibited by the AISI 1020 carbon steel. The experiments confirm that the cladding surfaces of TiC particles reduce the wear rate and friction.     

W18Cr4VCo5钢表面PCVD复合陶瓷涂层的摩擦学研究

用等离子体化学气相沉积(PCVD)技术对挤压模具钢表面进行复合陶瓷强化处理，用环一块摩擦磨损试验模拟金属挤压的磨损过程，研究了复合陶瓷表面强化涂层的摩擦磨损特性。用俄歇电子能谱(AES)、X射线衍射(XRD)和扫描电镜(SEM)分析了表面涂层的元素分布、相结构和磨痕形貌。结果表明，W18Cr4VCo5钢表面PCVD陶瓷涂层具有显著减摩抗磨能力。     

Microscopic real time observation of failure, wear and deformation on coating/subsurface

The deposition of surface coatings on industrial component is widely used for reducing wear and friction in the tribological application. Tribological properties of various kinds of coatings have been systematically analyzed. This paper mainly deals with the investigation of failure mechanism of the coating/subsurface through the microscopic observation in real time through the repetition of sliding friction. The results of observations suggest that the mechanical failure is characterized by the intrinsic properties of coating and substrate materials, e.g. the relation between the thickness of coating and the depth of the plastically deformed region in the substrate. In the present study the microscopic real time observation is performed to investigate the failure of coating/subsurface by use of ‘frictional surface microscope system’, which is assembled by combining a metallographic microscope and a frictional device operated in the field of view of the microscope.     

Al2O3/TiC/CaF2自润滑陶瓷刀具切削过程中的减摩机理

在Al2O3/TiC陶瓷刀具基体内加入固体润滑剂CaF2来改善其摩擦学特性,制备出Al2O3/TiC/CaF2自润滑陶瓷刀具.以该陶瓷刀具对45钢进行干切削试验,结果表明添加固体润滑剂的Al2O3/TiC/CaF2自润滑刀具的摩擦因数比未添加固体润滑剂的Al2O3/TiC陶瓷刀具显著降低,表现出了良好的减摩效果.在切削过程中,Al2O3/TiC/CaF2自润滑陶瓷刀具中的固体润滑剂由于受到摩擦和挤压作用而析出,能在刀具前刀面上形成润滑膜,可阻止刀-屑间的粘着,显著降低前刀面与切屑间的平均摩擦因数.对自润滑陶瓷刀具切削后磨损表面显微分析表明,前刀面在切削过程中形成了自润滑膜的生成、破损、脱落和再生的循环过程.因此,Al2O3/TiC/CaF2自润滑陶瓷刀具在其整个生命周期内始终具有润滑效果.     

Effect of reinforcing submicron SiC particles on the wear process of electrolytic NiP coatings

The effect of submicron silicon carbide frictional strengthening admixtures and heat treatment on the wear process of nickel phosphide coatings obtained by electrolytic deposition is studied. Despite the heat treatment and admixtures of silicon carbides, the wear of the coatings is of abrasion-oxidizing nature; in the case of NiP-SiC composite coatings, the oxide films formed during the friction process do not exhibit the shield effect; these films show a considerable effect on the wear of silicon-free NiP coatings. The silicon carbide admixtures increase the hardness of the electrolytic coatings but prevent the oxide films formed in the frictional process from attaching to the contact surface. Annealing of the coating reduces the wear rate. In the process of heat treatment, the crystalline phase Ni₃P is formed in the NiP matrix, increasing the coating hardness. At the same time, in the process of annealing of NiP-SiC composite coatings, the NiP matrix cracks around the silicon carbides. As a result, silicon carbides are extracted in the frictional process and the wear rate of the NiP-SiC composite coating grows.     

稀土化合物改性复合材料在油润滑下的摩擦学性能

以竹纤维为增强相,通过稀土化合物改性制备一种树脂基复合材料;采用环块式摩擦磨损实验,研究稀土化合物改性复合材料在油润滑状态下载荷、转速对试样摩擦学性能的影响,以及稀土化合物改性对复合材料试样摩擦学性能的影响;比较干摩擦状态和油润滑状态下复合材料的摩擦学性能,观察和分析试样磨损表面形貌,探讨其磨损机制。实验结果表明:油润滑条件下,稀土化合物改性复合材料的摩擦因数和磨损率都随着载荷的增大而增加;较高载荷下摩擦因数随着转速的增大先增加后减小,而磨损率则呈现逐步增加的趋势;稀土化合物的改性使竹纤维和基体界面结合更为紧密,提高摩擦因数的同时降低了磨损率;在油润滑作用下,试样磨损由干摩擦时的磨粒磨损和疲劳磨损转变成为轻微的疲劳磨损;在油润滑状态下,复合材料处于边界润滑状态,故摩擦因数和磨损率均低于干摩擦。