化学镀Ni—P合金与油溶性有机钼复合摩擦学性能

摩擦磨损试验表明,化学镀Ｎｉ－Ｐ合金镀层（基体为调质４５钢）与油溶性有机钼添加剂（ＭｏＤＴＣ）有良好的协同效应,如Ｎｉ－Ｐ合金镀层（热处理,油中加ＭｏＤＴＣ）比４５钢基础油润滑下,摩擦系数降低４１．５％,耐磨性提高７倍,采用电子探针等研究了其摩擦磨损机理,结果表明,上述协同效应取决于摩擦表面所形成的ＭｏＳ２保护膜,Ｎｉ－Ｐ合金镀层的高硬度及其特殊的组织结构。     

硅酸铝／ZL101复合材料的摩擦性能

利用液诚浸渗法制备了硅酸铝短纤维／ＺＬ１０１复合材料,并对其显微组织、摩擦性能及摩擦机制进行了分析。结果表明,硅酸铝短纤维／ＺＬ１０１复合材料的耐磨性远高于ＺＬ１０１合金,且其摩擦系统明显低于ＺＬ１０１合金,热处理对得合材料及ＺＬ１０１合金的摩擦系数及其耐磨性均有影响,ＭＭＣ的摩擦磨损机理以氧化－磨粒磨损为主,其摩擦力主要由基体与对磨环的粘着生产。     

氧化镧掺杂对等离子喷涂Al_2O_3-40%TiO_2涂层组织和耐磨性能的影响

在45#钢基体上大气等离子喷涂制备了Al2O3-40%TiO2(AT40)以及添加不同含量La2O3稀土的陶瓷涂层,利用X射线衍射和扫描电镜对涂层的组织结构和形貌进行了研究,并分析了涂层的显微硬度和磨损性能.研究结果表明:添加稀土的AT40涂层主要是由Al2O3、Al2TiO5和LaAl11O8相组成.基体与粘结层以及陶瓷层与粘结层之间形成良好的机械结合界面.添加稀土的涂层孔隙率降低,显微硬度和断裂韧性略有增加.在相同的摩擦磨损试验条件下,稀土/AT40涂层比AT40涂层具有更好的耐磨性,磨损机制都主要是脆性剥落磨损和粘着磨损.     

锰白铜合金/W_2C复合涂层磨损机制研究

采用无压浸渍工艺,在45#钢表面制备出2种锰白铜合金/W2C复合涂层;考察了比压、转速及W2C颗粒尺寸对涂层与石油钻机的一种新型刹车材料对磨的耐磨性的影响,并分析了涂层的磨损过程与磨损机制。结果表明:涂层的磨损机制是W2C颗粒的疲劳磨损以及摩擦表面氧化锰薄膜和表面膜的生成、长大、破裂(撕裂)、剥落、再生的动态磨损过程,也是磨粒磨损、疲劳磨损、黏着磨损、塑性变形和氧化磨损等磨损机制的综合作用。     

青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能

在MM-200摩擦磨损试验机上研究了青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能,采用扫描电镜(SEM)对磨损表面形貌进行了观测和采用X射线能谱分析(XPS)分析了涂层成分。结果表明,在水润滑条件下涂层摩擦因数和磨损率均低于干摩擦条件下;在水润滑条件下磨损机制为轻微磨粒磨损和犁削磨损,在干摩擦下主要是较为严重的粘着磨损和犁削。这是由于水润滑降低了摩擦副界面温度,提高了石墨润滑膜的韧性,改善了润滑效果,从而阻止了粘着磨损的发生,水还促进了钢偶件表面致密氧化膜的形成,从而减轻磨损。因此水润滑对涂层磨损性能有较大影响。     

TP1000涂层刀具车削淬硬钢的磨损与破损形态

用TP1000涂层刀具对淬硬45钢和淬硬T10A钢进行了正交车削实验,并进行了相应的扫描电镜(SEM)和X射线衍射(XRD)分析。结果表明,切削淬硬45钢时,涂层刀具发生了磨损和破损,磨损机理主要是磨料磨损和氧化磨损,破损机理主要是涂层剥落。切削淬硬T10A钢时,涂层刀具主要发生破损,破损机理主要是涂层开裂、剥落和崩刃。     

化学镀Ni—B合金与有机钼对金属基体的双重保护

采用表面镀层和润滑油中加入某些添加剂，使两者产生协同效应，是减少相对运动的零件表面间摩擦磨损的一项有效措施，本文研究了Ｎｉ－Ｂ合金镀层与油溶性有机钼的联系及摩擦磨损机理，摩擦磨损实验结果表明，Ｎｉ－Ｂ合金镀层与油溶性有机钼（ＭｏＤＴＰ）有良好的协同效应，可大幅度提高运动副的减摩性和耐磨性，如Ｎｉ－Ｐ合金镀层经４０℃热处理，油中加ＭｏＤＴＰ比４５钢基础油润滑下，耐磨性提高１２．８倍，摩擦系数降低５４     

Fe基非晶涂层的组织结构与耐磨性研究

利用电弧喷涂技术在45#钢基体上制备了Fe基非晶合金涂层。与YG8球配副,在干摩擦条件下对涂层与45#钢的摩擦磨损性能进行了对比研究。采用XRD、扫描电镜及显微硬度计等分析仪器对涂层组织结构及磨损形貌进行表征。结果表明:涂层中含有非晶相,孔隙率较少,涂层平均硬度高达HV1124。与45#钢相比,涂层的摩擦因数较小,耐磨性明显高于45#钢基体,其磨损机制以片状剥落为主。     

Y15钢表面直接涂层处理滑动摩擦磨损试验研究

在易切削钢Y15试样表面直接涂层处理得到TiCN、AlTiCrN涂层,在SRV Ⅳ磨损试验机上考察其摩擦磨损性能,并与TiN直接涂层试样、盐浴渗氮试样进行比较。结果表明：直接涂层试样比盐浴渗氮试样具有更低的摩擦因数和更好的耐磨性;TiCN直接涂层耐磨性最好,其次为AlTiCrN直接涂层。盐浴渗氮试样、直接TiN涂层试样和直接TiCN涂层试样的磨损机制以黏着磨损为主,而直接AlTiCrN涂层试样的磨损机制以黏着磨损为主,同时也存在磨粒磨损。     

Y15钢表面TiCN和AlTiCrN涂层滑动摩擦试验研究

在易切削钢Y15试样表面直接涂层处理得到TiCN、AlTiCrN涂层,在SRV Ⅳ磨损试验机上考察其摩擦磨损性能,并与TiN直接涂层试样、盐浴渗氮试样进行比较。结果表明:直接涂层试样比盐浴渗氮试样具有更低的摩擦因数和更好的耐磨性;TiCN直接涂层耐磨性最好,其次为AlTiCrN直接涂层。盐浴渗氮试样、直接TiN涂层试样和直接TiCN涂层试样的磨损机制以黏着磨损为主,而直接AlTiCrN涂层试样的磨损机制以黏着磨损为主,同时也存在磨粒磨损。     

Wear Characteristics of Large Grinding Balls in an SAG Mill

The wear characteristics of larger than 120 mm-diameter grinding balls used in large semiautogenous (SAG) mills is studied in the present paper. SEM observation on the worn ball surface reveals a severe microcutting process. Abrasion grooves can be found on the overall surface. Moreover, persistent microcracks are found on the surface. The observation on the cross section indicates extended white layers and white bands exist in the subsurface of worn balls. The white layer is not homogenous on the surface. The largest white layer is about 20 μm thick and 1.3 mm long. The wear resistance of the white layer is tested with a simulated high stress impact wear tester. It is found that the white layer is associated with delamination wear, which significantly increases the wear rate. The delamination wear mechanism is explained from the intensely deformed microstructure and microcracks inside the white layer. Based on the experimental results, a wear formula consisting of both microcutting wear and delamination wear is submitted. This formula means that high wear resistance is only achieved when the hardness and fracture toughness of grinding balls are increased simultaneously.     

感应熔敷微-纳米碳化钨复合涂层的耐磨性研究

用感应加热熔敷方法在Q235钢表面制备了微-纳米碳化钨复合涂层，并分析了涂层的微观结构、显微硬度及耐磨性。结果表明：涂层的组织主要由镍基固溶体和碳化钨颗粒组成。涂层与基体冶金结合；微-纳米碳化钨涂层的耐磨性比微米碳化钨涂层平均提高0．5倍。     

Sliding wear behavior of Fe-Al and Fe-Al/WC coatings prepared by high velocity arc spraying

A comparative study was carried out to investigate the microstructure and tribological behavior of Fe-Al and Fe-Al/WC iron aluminide based coatings against Si₃N₄ under dry sliding at room temperature using a pin-on-disc tribotester. The coatings were prepared by high velocity arc spraying (HVAS) and cored wires. The effect of normal load on friction coefficient and wear rate of the coatings was studied. The microstructure and the worn surfaces of the coatings were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscope (EDS). The results showed that, the main phases in both coatings were iron aluminide (Fe₃Al and FeAl) and α. WC/W₂C particles were embedded in the matrix of the composite coating. With adding WC hard particles, the Fe-Al/WC composite coating exhibited higher wear-resistance than Fe-Al coating. But the friction coefficient of both coatings showed little difference. As the load increased, the friction coefficient decreases slightly due to a rise of friction contact temperature and larger areas of oxide film formation on the worn surface, which act as a solid lubricant. Increasing load causes the maximum shear stress occurring at the deeper position below the surface, thereby aggravating the wear. The coating surface is subjected to alternately tensile stress and compression stress during sliding, and the predominant wear mechanism of the coatings appears to be delamination.     

电火花放电熔涂层在边界润滑条件下的磨损特性

用环块磨损试验机对铬电极电火花熔涂层及淬火低温回火态45^#钢的边界润滑滑动磨损特性进行了研究。结果表明,轻载低速条件下,熔涂层与45^#钢的边界润滑滑动磨损机制以犁沟划伤为主,熔涂层的磨损量与45^#钢的相当;重载高速条件下,熔涂层的磨损机理以粘着磨损和磨料磨损为主,而45^#钢的磨损机理以点蚀剥落为主：熔涂层的磨损量远比45^#钢的人。     

Surface durability of WC/C-coated case-hardened steel gear

The purpose of this study is to investigate the influence of tungsten carbide/carbon (WC/C) coating on the surface durability of casehardened steel gear. Two kinds of WC/C coatings were deposited on the ground gear pair made of chromium molybdenum steel with carburizing and quenching. One is the conventional WC/C coating, and the other is WC/C coating with about 1 μm CrN interlayer. Here, the WC/C-coated test pinion and the WC/C-coated one with CrN interlayer are represented by WT and ST, respectively. Non-coated test pinion is represented by NT. The surface roughness along the tooth profile direction of WT and ST was almost the same as that of NT. A spur gear test was carried out with an IAE power circulating type gear test rig under EP gear oil lubricating condition. The fatal failure mode of the test pinions was pitting due to surface cracking. The fatigue life of WT was longer than that of NT under a maximum Hertzian stress p _max=1700 MPa. On the other hand, under p _max=1900 MPa, that of WT was as long as that of NT due to the peeling occurrence of the coated layer. Under the comparatively low load condition without peeling occurrence, the surface roughness of WT decreased with the increasing number of cycles, and their fatigue life became longer than that of NT. On the contrary, in the case of ST, the peeling of the coated layer occurred at a comparatively early stage of the gear test, and the dedendum was worn by tens of micrometers. Therefore, in the case of ST, the effect of the WC/C coating disappeared at a comparatively small number of cycles.     

等离子喷涂WC/Co Fe基涂层摩擦与磨损性能

以普通铸铁为基体,碳化钨陶瓷粉末WC 12Co为热喷涂材料,采用大气等离子法制备WC/Co Fe复合涂层.通过SEM、EDS、XRD等手段对WC/Co Fe涂层微观组织与结构进行表征,并对WC/Co Fe复合涂层耐磨损性能进行测试.结果表明,等离子喷涂制备的WC/Co Fe涂层物相以WC相为主;WC涂层摩擦因数波动小于铸铁材料摩擦因数,表明WC复合涂层具有良好的抗摩擦性能.WC涂层耐磨损性能高于铸铁,主要归因于WC颗粒韧性好、硬度高、抗冲击及抗磨损性能强,与基体金属的结合性好.     

Microstructure and Tribological Properties of a HfB<Subscript>2</Subscript>-Containing Ni-Based Composite Coating Produced on a Pure Ti Substrate by Laser Cladding

A HfB₂-containing Ni-based composite coating was fabricated on Ti substrates by laser cladding, and its microstructure and tribological properties were evaluated during sliding against an AISI-52100 steel ball at different normal loads and sliding speeds. The morphologies of the worn surfaces were analyzed by scanning electron microscopy (SEM) and three-dimensional non-contact surface mapping. The results show that wear resistance of the pure Ti substrate and NiCrBSi coating greatly increased after laser cladding of the HfB₂-containing composite coating due to the formation of hard phases in the composite coating. The pure Ti substrate sliding against the AISI-52100 counterpart ball at room temperature displayed predominantly adhesive wear, abrasive wear, and severe plastic deformation, while the HfB₂-containing composite coating showed only mild abrasive wear and adhesive wear under the same conditions.     

WC颗粒增强镍基涂层改善制动盘组织与磨损性能

为提高汽车制动盘耐磨和高温氧化性能,延长其使用寿命,采用激光熔覆技术在中碳钢表面制备了以WC颗粒为增强相的Ni基复合涂层.借助SEM和XRD等表征手段对制动盘表面涂层进行了组织和物相分析,利用维氏硬度计测试了制动盘表面涂层截面显微硬度分布,通过摩擦磨损实验研究了制动盘表面涂层的磨损性能.研究表明,制动盘表面涂层主要由γ-（Ni,Fe）固溶体、均匀分布WC颗粒和碳化物抗磨损相组成.涂层平均显微硬度HV0.2670,显微硬度值波动较小较为平稳,证明涂层组织比较均匀.在多种强化效果共同作用下,制动盘表面涂层的磨损量与基材相比明显减小,仅为基材的20％,抗磨损性能显著提高.     

Dry-Sliding Tribological Properties of Bronze–Graphite Composites

Bronze-uncoated and nickel-coated graphite composites were fabricated by powder metallurgy route. The tribological behaviors of composites sliding against AISI52100 steel ball under dry sliding condition were studied using a ball-on-disk tribometer. The nickel-coated graphite composites showed much better tribological properties in comparison with bronze and uncoated graphite composite. The friction coefficient of nickel-coated graphite composites decreased with increasing nickel-coated graphite content. However, the specific wear rate increased with the increase in nickel-coated graphite. The composite containing 15?wt% nickel-coated graphite showed the best self-lubricating properties because the compacted and stable mechanical mixed layer was formed on the worn surfaces. The wear mechanism of bronze 663 is adhesive wear and abrasive wear. The uncoated nickel-coated graphite composite shows the adhesive wear and delamination characteristics. However, the wear mechanism of nickel-coated composites is mildly abrasive wear.     

The microstructure and wear behaviour of friction stir processed AISI 430 ferritic stainless steel

ABSTRACT

The microstructure and wear behavior of Friction Stir Processed (FSPed) AISI 430 ferritic stainless steel were analyzed in the present study. FSP was performed with a tool rotation and advancing speeds of 1400?rpm 16?mm/min respectively by employing a tungsten carbide tool. The FSPed microstructure consisted of a mixture of ferrite and martensite. After FSP, microhardness increased with respect to that of the as-received material. The wear resistance of the FS processed material was significantly enhanced if compared to that of the as-received substrate. According to the SEM analyses of the worn surfaces and wear debris, a combination of adhesive wear and delamination was observed in the case of the base metal. The wear mechanism shifted to mild adhesive wear after FSP. The superior wear resistance of the FS processed AISI 430 steel was attributed to the pronounced grain refinement and to martensite formation in the stir zone.