Approach for Polishing Diamond Coated Complicated Cutting Tool: Abrasive Flow Machining(AFM)

Lower surface roughness and sharper cutting edge are beneficial for improving the machining quality of the cut?ting tool, while coatings often deteriorate them. Focusing on the diamond coated WC?Co milling cutter, the abrasive flow machining(AFM) is selected for reducing the surface roughness and sharpening the cutting edge. Comparative cutting tests are conducted on di erent types of coated cutters before and after AFM, as well as uncoated WC?Co one, demonstrating that the boron?doped microcrystalline and undoped fine?grained composite diamond coated cutter after the AFM(AFM?BDM?UFGCD) is a good choice for the finish milling of the 6063 Al alloy in the present case, because it shows favorable machining quality close to the uncoated one, but much prolonged tool lifetime. Besides, compared with the micro?sized diamond films, it is much more convenient and e cient to finish the BDM?UFGCD coated cutter covered by nano?sized diamond grains, and resharpen its cutting edge by the AFM, owing to the lower initial surface roughness and hardness. Moreover, the boron incorporation and micro?sized grains in the underly?ing layer can enhance the film?substrate adhesion, avoid the rapid film removal in the machining process, and thus maximize the tool life(1040 m, four times more than the uncoated one). In general, the AFM is firstly proposed and discussed for post?processing the diamond coated complicated cutting tools, which is proved to be feasible for improving the cutting performance     

A comparative study of the friction and wear behavior of untreated mild steel and its boron-permeated counterpart under lubrication of liquid paraffin containing zinc dialkyldithio-phosphate

AISI-1045 steel was treated with solid boron permeation, and the interaction between the modified surface layer and the lubricating additive zinc dialkyldithio-phosphate (ZDDP) was examined. The friction and wear behavior of the treated and untreated steel specimens were compared. The phase composition of the boron-permeated layer was examined by means of X-ray diffraction. The chemical states of several typical elements on the worn surfaces of the treated and untreated steel surfaces were examined by means of Auger electron spectroscopy and X-ray photoelectron spectroscopy. Results showed that the wear-resistance of boron-permeated specimens was higher than that of the untreated ones. This was partly attributed to the change in the hardness and phase composition of the steel surfaces after boron permeation. Tribochemical reactions between steel and the active elements of the additive occurred during the sliding of the treated and untreated steel discs against an AISI-52100 steel ball using different lubricants. The resultant surface protective films containing various tribochemical products, together with the adsorbed boundary lubricating film, contributed to the reduction of friction and wear.     

CVD金刚石薄膜的掺硼研究

采用固体三氧化二硼，在单晶硅（100）衬底上用微波CVD法生长金刚石薄膜和进行p型掺杂，对不同掺杂碳源浓度下CVD金刚石薄膜的掺杂和生长行为、薄膜表面形貌、薄膜的电性能等进行了研究。结果表明，硼确实已掺入金刚石膜中；在SEM下观察到硼掺杂金刚石膜结构致密没有孔洞；用Ti和Ag分别在掺杂金刚石薄膜表面制备电极，测试了在不同温度下电流随温度的变化。     

Tribological properties of lubricated nanocrystalline diamond surfaces for various loads and geometries

Abstract

Diamond and diamond-like carbon films are well known for their outstanding properties such as high hardness, low coefficient of friction, good thermal conductivity, excellent biocompatibility and electrical insulation. Diamond films with nanocrystalline grains offer added advantages of higher hardness, improved surface finish (less roughness), very high sp³ content, etc. In view of the above, the present investigation is undertaken to explore the possibility of using nanocrystalline diamond films in advanced tribological applications. In this work, a nanocrystalline diamond film is deposited using a unique chemical vapour deposition (CVD) technique. The microstructural features are characterised using atomic force microscopy (AFM). Tribological behaviour of these films is evaluated by means of a reciprocating model tribometer with various lubricants. The worn surfaces are examined using three-dimensional confocal microscopy. The results show that these films have comparable friction coefficient with and without lubricants. Furthermore, they exhibited negligible wear for the tested range of loads.     

Tribological behavior between micro- and nano-crystalline diamond films under dry sliding and water lubrication

The tribological behavior of micro- and nano-crystalline diamond films is evaluated in dry sliding and water lubricating condition. The main wear mechanism is found to be abrasive wear mode induced by self-polishing. Non-diamond components and higher compressive residual stresses are detected in flat MCD films after dry sliding, in comparison to NCD. Origin of decreased friction coefficient in CVD diamond tribosystems under water lubrication is attributed to the effect of water on the formed graphic material and the chemisorbing of diamond surface with H₂O, hydrogen or hydroxyl ions. For the MCD/NCD or NCD/MCD contact, the surface roughness of ball largely determines the stable friction coefficient in dry sliding, where NCD film usually presents higher wear rate.     

直流等离子体喷射法制备氮化碳涂层的研究

氮化碳因预言具有超金刚石硬度、高热稳定性及优异的摩擦磨损性能,在刀具涂层的应用领域具有巨大的潜力,引起了世界上科研工作者的广泛关注。本文以CF4+N2+H2+Ar为反应气体,通过直流等离子体喷射法(DC Plasma Jet CVD),在Si[100]基底上以金刚石薄膜为过渡层,成功制备了氮化碳涂层。利用扫描隧道显微镜(SEM)、原子力显微镜(AFM)、拉曼光谱(Raman)等现代理化测试手段,对所制备涂层的表面形貌、成分结构进行了表征和分析。研究结果表明:所制备的涂层中金刚石过渡层表面生长了线度约300-600nm的C3N4晶粒,为亚微米级别,晶形较为清晰,呈现不规整的柱状,样品中主要含有α-C3N4与β-C3N4,涂层中N的含量为9.8%。     

Friction and wear of diamondlike carbon on fine-graindiamond

Friction and wear behavior of ion-beam-deposited diamondlikecarbon (DLC) films coated on chemical-vapor-deposited (CVD),fine-grain diamond coatings were examined in ultrahigh vacuum,dry nitrogen, and humid air environments. The DLC films wereproduced by the direct impact of an ion beam (composed of a 3 :17 mixture of Ar and CH₄) at ion energies of 1500 and700 eV. Sliding friction experiments were conducted withhemispherical CVD diamond pins sliding on four differentcarbon-base coating systems: DLC films on CVD diamond; DLC filmson silicon; as-deposited, fine-grain CVD diamond; andcarbon-ion-implanted, fine-grain CVD diamond on silicon. Resultsindicate that in ultrahigh vacuum theion-beam-deposited DLC films on fine-grain CVD diamond (similarto the ion-implanted CVD diamond) greatly decrease both thefriction and wear of fine-grain CVD diamond films and providesolid lubrication. In dry nitrogen and in humid air,ion-beam-deposited DLC films on fine-grain CVD diamond films alsohad a lowsteady-state coefficient of friction and a low wear rate. Thesetribological performance benefits, coupled with a wider range ofcoating thicknesses, led to longer endurance life and improvedwear resistance for the DLC deposited on fine-grain CVD diamondin comparison to the ion-implanted diamond films. Thus, DLCdeposited on fine-grain CVD diamond films can be an effectivewear-resistant, lubricating coating regardless of environment.     

CVD金刚石涂层刀具切削性能的试验研究

金刚石薄膜具有高硬度、低摩擦系数、高耐磨性和高导热性能。文中通过用金刚石薄膜涂层刀具对含硅量不同的硅铝合金进行干切削试验,探讨其切削性能。     

Hardness effect of stainless steel substrates on tribological properties of water-lubricated DLC films against AISI 440C ball

Diamond-like carbon (DLC) films were deposited on stainless steel substrates with different hardness by thermal electron excited plasma CVD method, and their tribological properties in water-lubricated conditions were investigated. EDS was used to estimate the wear of the films. The results show that the hardness of the substrates has little effect on the friction and, the wear loss of the films is much smaller than that measured by an optical interferometer. The deep wear track is mainly due to the plastic deformation of the substrates and the films but not due to wear. However, the failure of the films is closely related to the hardness of their substrates. The harder the substrate, the higher the failure-resistant capability. The film deposited on a soft substrate is easy to crack and fail due to the low deformation resistance of the substrate and rubbing at a high contact-pressure. On the other hand, the wear of the counter balls increases with the hardness of the substrates.     

V含量对TaVN薄膜微观结构与摩擦学性能的影响*

为探讨V元素改善TaN薄膜摩擦学性能的机制,利用磁控溅射仪在304不锈钢基体上和单晶Si片制备不同V含量的 TaVN薄膜。使用X射线衍射仪、扫描电镜、显微硬度计、表面综合性能测试仪表征和分析薄膜的结构及性能。结果表明：TaVN 薄膜为面心立方结构,不同V含量的TaVN薄膜均在（111）晶面呈现择优取向;随着V含量的增加,TaVN 薄膜（111）晶面出现向大角度偏移的现象;不同V含量的TaVN 薄膜在扫描电子显微镜下的表面光滑平整无孔隙,膜层与基体间界面清晰,截面呈明显的柱状晶结构;随着V含量的增加,TaVN 薄膜硬度先升高后降低,当TaV靶材中V原子分数为15%时,硬度最高;随着V含量的增加,摩擦因数降低,其原因是在摩擦的过程中,薄膜中的V元素氧化形成具有自润滑效果的Magnéli 相氧化物V2O5;随着V含量的增加,TaVN 薄膜磨损机制由磨粒磨损、黏着磨损和氧化磨损转变为磨粒磨损和氧化磨损。     

MoS2/WS2复合薄膜的环境适应性和摩擦学性能

湿热大气环境对MoS2润滑薄膜的摩擦学性能有严重的劣化作用。采用非平衡磁控溅射技术成功制备了WS2掺杂MoS2复合薄膜,研究发现,MoS2基体中掺入少量WS2可以诱导MoS2沿（002）晶面择优生长,薄膜结构变得更加致密,显著抑制腐蚀介质的渗透和扩散,使MoS2/WS2复合薄膜展现出高盐雾耐蚀性、小摩擦因数和低磨损率。成分优化的MoS2-1.6%WS2（原子分数）复合薄膜在经历4天的盐雾试验后仅表层被氧化,仍能保持0.16的小摩擦因数和3.80 × 10-6 mm3/（N·m）的低磨损率。     

射频磁控溅射法制备氮化硼薄膜

采用射频磁控溅射方法在T10钢表面获得了氮化硼薄膜。借助光学显微镜、摩擦磨损试验仪和划痕试验仪等研究了溅射时间、溅射功率以及中间层对薄膜性能的影响。结果表明：氮化硼薄膜的摩擦因数约为钢基材料的一半,中间层镍磷合金的加入使薄膜结合力显著提高。     

Mechanical and tribological properties of phenolic resin-based friction composites filled with several inorganic fillers

The calcined petroleum coke (CPC), talcum powder (TP) and hexagonal boron nitride (h-BN) were used as the friction modifiers to improve the mechanical and tribological properties of phenolic resin-based friction composites (the resin matrix was coded as PHE). Thus the composites filled with the inorganic particulates of laminar structures were prepared by compression molding. The hardness and bending strength of the friction composites were measured. The tribological properties of the composites sliding against cast iron were evaluated using a pin-on-disc test rig. The morphologies of the worn surfaces of the composites and the transfer films on the counterpart cast iron disc were analyzed by means of scanning electron microscopy, and the elemental plane distributions on the transfer films were analyzed using energy-dispersive X-ray analysis (EDXA). It was found that the friction composites of different compositions showed different friction and wear behaviors, which was highly dependent on the volume fractions of the friction modifiers in the composites. Namely, the inclusion of CPC, h-BN, and TP at a volume fraction of 10% helped to greatly increase the bending strength and wear resistance of the composites, and in these cases the coefficients of friction for the composites were ranged within 0.43–0.47. In particular, the PHE-based composite with 10% h-BN had excellent friction stability at various testing conditions and showed the best wear resistance above 125 °C, which was attributed to the formation of a compact friction film (third-body-layer) on the rubbing surface of the composite and of a durable transfer film on the rubbing surface of the counterpart cast iron. The PHE-based composite with 10% CPC showed the best wear resistance below 125 °C, which was ascribed to the same reasons mentioned above. The different actions of various friction modifiers in terms of their effects on the friction and wear behavior of the phenolic resin-based friction composites could be related to their different bonding strengths with the resin matrix and their different abilities to form friction films (third-body-layer) on the surfaces of the composites and transfer films on the counterpart cast iron surface as well.     

CVD金刚石厚膜刀具切削性能的试验研究

分析了CVD金刚石厚膜刀具材料的性能特点 ,对CVD金刚石厚膜车刀进行了精密切削和难加工复合材料切削试验 ,结果表明 :CVD金刚石厚膜刀具加工铝合金的表面粗糙度可达Ra0 0 5 μm ;切削难加工复合材料时刀具耐磨性和使用寿命明显优于硬质合金刀具、PCBN刀具和PCD刀具     

Tribological properties of plasma nitrided stainless steel against SAE52100 steel under ionic liquid lubrication condition

1Cr18Ni9Ti stainless steel was modified by plasma nitriding. The phase composition of the plasma nitrided layer was examined by means of X-ray diffraction. The friction and wear properties of the modified and unmodified 1Cr18Ni9Ti stainless steel specimens sliding against SAE52100 steel under the lubrication of ionic liquid of 1-ethyl-3-hexylimidazolium hexafluorophosphate (L-P308) and poly α-olefin (PAO) were investigated on an Optimol SRV oscillating friction and wear tester, with the interactions among the modified surface layer and the ionic liquids and PAO to be focused on. The morphologies of the worn surfaces were observed using a scanning electron microscope. The chemical states of several typical elements on the worn surfaces of the modified steel surfaces were examined by means of X-ray photoelectron spectroscopy. Results showed that the modified sample had better anti-wear abilities than the unmodified one, but the modified sample had a slightly higher friction coefficient than the untreated one. This was partly attributed to the change in the hardness and phase composition of the stainless steel surfaces after plasma nitriding and tribochemical reactions between the steel and the lubricant. The resultant surface protective films composed of various tribochemical products together with the adsorbed boundary lubricating film contributed to reduce the friction and wear.     

模具钢表面多弧离子镀CrAlN涂层的制备及其摩擦性能研究

为了改善模具钢表面质量,采用多弧离子镀技术在H13模具钢表面沉积CrAlN薄膜,探讨H13钢基体表面渗氮处理后对薄膜表面形貌、硬度、结合力、抗氧化性和摩擦磨损性能的影响。结果表明：基体表面渗氮处理前后制备的CrAlN涂层表面均匀致密,都有少量的大颗粒,涂层表面均呈CrN（200）面择优取向,而渗氮后制备的涂层CrN（200）面择优取向更强;基体H13钢经过表面渗氮后,硬度显著提高,对制备的涂层具有支撑作用,降低了裂纹产生倾向,提高了涂层产生裂纹的临界载荷,提高了涂层的膜基结合力;相较于基体表面未渗氮处理制备的CrAlN涂层,基体表面渗氮后制备的CrAlN涂层具有更高的硬度和结合力,更为优异的摩擦磨损性能,且抗高温氧化性能显著增强。     

碳黑填充PTFE复合材料干摩擦磨损性能分析

以碳黑为填料制备了PTFE基复合材料,并研究了该复合材料在干摩擦条件下与不锈钢对摩时的摩擦磨损行为,并探讨其磨损机制。实验结果表明,碳黑/PTFE复合材料的摩擦因数随着碳黑含量的增加呈增加的趋势,其耐磨性能明显优于纯PTFE。当碳黑的质量分数为5%时,其抗磨性能最好。SEM观察发现纯PTFE的断面上分布着大量的带状结构,而填充了碳黑后,则未观察到这种带状结构,这说明碳黑有效地抑制了PTFE结构的破坏。对PTFE和碳黑/PTFE复合材料的摩擦表面的SEM观察发现,前者的摩擦表面分布着较明显的犁削和粘着磨损的痕迹,而后者的摩擦表面则平整光滑,这表明以碳黑作为填料可有效地抑制PTFE的磨损。     

Tribological properties of metal-plastic multilayer composites under oil lubricated conditions

Three kinds of metal-plastic multilayer composites, which were composed of a steel backing, a middle layer of sintered porous bronze and a surface layer of polytetrafluoroethylene (PTFE) filled by Pb or Cu₂O powders, were prepared. The friction and wear properties as well as the limiting pressure times velocity (PV) values of these metal-plastic multilayer composites sliding against 45 carbon steel under both dry and oil lubricated conditions were evaluated on a MPV-1500 friction tester with a steel axis rotating on a journal bearing. The worn surfaces of these metal-plastic multilayer composites and the transfer films formed on the surface of steel axis were examined by electron probe microscopy analysis (EPMA). Experimental results show that filling of Pb to PTFE reduces the friction coefficient and wear of the composite, while filling of Cu₂O to PTFE increases the friction coefficient but decreases the wear of the composite. The friction and wear properties as well as the limiting PV values of these metal-plastic multilayer composites can be greatly improved with the oil lubrication. EPMA investigations show that Pb and Cu₂O fillers preferentially transfer onto the surfaces of steel axis, which may enhance or deteriorate the adhesion between transfer films and steel surfaces. Meanwhile the transfer of these metal-plastic multilayer composites onto the steel surface can be greatly reduced with oil lubrication, which results in the remarkable decrease of the wear of these metal-plastic multilayer composites.     

刀具的抗磨和减摩镀层

对刀具镀层发展过程的回顾表明，以提高硬度为目标的耐磨镀层已经逐步向具有自润滑功能的耐磨减摩镀层方向发展。结合我们自己的工作，给出了硫化钼、碳膜等镀层的摩擦学性能的研究结果。     

Tribological Performance of Diamond and Diamondlike Carbon Films at Elevated Temperatures

In this study, the authors investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a reciprocating wear machine in open air (20 to 30% relative humidity) and under a 10 N load using SiC pins. For the test conditions explored, the steady-state friction coefficients of test pairs without a diamond or DLC film were 0.7 to 0.9 and the average wear rates of pins were 10^?5 to 10^?7 mm³/N·m, depending on ambient temperature. DLC films reduced the steady-slate friction coefficients of the test pairs by factors of three to five and the wear rates of pins by two to three orders of magnitude. Low friction coefficients were also obtained with the diamond films, but wear rates of the counterface pins were high due to the very abrasive nature of these films. The wear of SiC disks coated with either diamond or DLC films was virtually unmeasurable while the wear of uncoated disks was substantial. Test results showed that the DLC films could afford low friction up to about 300° C. At higher temperatures, the DLC films graphitized and were removed from the surface. The diamond films could withstand much higher tempera-lures, but their tribological behavior degraded. Raman spectroscopy and scanning electron microscopy were used to elucidate the friction and wear mechanisms of both films at high temperatures.