钨与钒掺杂类金刚石薄膜的温度适应摩擦磨损机制研究

通过非平衡磁控溅射技术,改变沉积工艺参数,在不锈钢及单晶硅基体上制备未掺杂、钨(W)掺杂以及钒(V)掺杂类金刚石(DLC)薄膜。采用拉曼光谱,纳米压痕法对薄膜结构和力学性能进行表征。在室温、250℃、500℃进行磨损实验,研究其不同温度范围的摩擦磨损性能。研究结果表明:适量掺杂W元素,可显著地提高W-DLC膜力学与摩擦性能,在W靶电流为0.6A条件下,W-DLC膜具有最优的综合性能,纳米硬度和弹性模量分别为11.11GPa和169.25GPa,其中在250℃条件下摩擦系数低至0.044,室温磨损率为1.27×10-7 mm~3/Nm,但W-DLC薄膜难以适应高温;适量掺杂V元素,可以显著提高V-DLC膜的纳米硬度和弹性模量,并能改善高温摩擦性能,在V靶功率为1.2kW条件下,V-DLC薄膜的纳米硬度和弹性模量分别为37.36GPa和379.89GPa,其中在500℃高温摩擦条件下,V-DLC薄膜的摩擦系数最低为0.35。     

Ti6Al4V表面磁控溅射高硬SiC薄膜的摩擦磨损性能

采用室温磁控溅射技术在Ti6Al4V表面制备出高硬SiC薄膜,对其组织结构、纳米压痕行为和摩擦磨损性能进行了研究。结果表明:实验制备的SiC薄膜呈非晶态,其纳米硬度、弹性模量分别为26.8GPa和229.4GPa;在以氮化硅球(半径为2mm)为对摩件的室温Kokubo人体模拟体液下,其磨损速率在10-5 mm3 m-1 N-1级,载荷低(50g)时摩擦因数约为0.173,载荷高(200g)时摩擦因数约为0.280,此时薄膜自身发生局部破裂。     

电弧增强磁控溅射制备的纳米复合Si-C-N超硬薄膜的结构与性能

耐磨、韧性好的超硬薄膜工程应用价值大。采用电弧增强磁控溅射(AEMS)技术在GCr15轴承钢表面制备了纳米复合Si-C-N超硬薄膜,研究了薄膜的形貌、相组成、硬度、韧性和摩擦磨损性能。结果表明:薄膜中纳米SiC与Si3N4晶体弥散分布于C-C,C=C以及N-C组成的非晶相基体中,形成了纳米晶/非晶复合组织结构,显著提高了薄膜的硬度和韧性,增强了薄膜的抗摩擦磨损性能;薄膜的硬度为(36.5±3.9)GPa,断裂韧性为(4.15±0.28)MPa.m1/2,稳定摩擦系数为0.27左右。     

纳米铜润滑油添加剂的摩擦学特性及其自修复机理

为了评价纳米铜添加剂对摩擦副的减摩和自修复性能,采用液相化学还原法合成了二烷基二硫代磷酸(HDDP)修饰纳米铜微粒,利用四球摩擦磨损试验机分析了不同载荷条件下纳米铜添加量对摩擦系数、磨斑直径等摩擦学性能影响,采用扫描电镜(SEM)和X射线光电子能谱仪(XPS)分析了磨痕形貌及其化学成分组成,并通过纳米压痕测试技术测量铜膜硬度及弹性模量。结果表明:纳米铜添加量为0.4%(质量分数)时减摩效果最佳,磨斑直径和摩擦系数明显下降,比未添加纳米铜的降低了23.0%~27.2%和15.1%~24.9%。摩擦过程中纳米铜微粒在摩擦表面形成化学沉积膜,铜膜的纳米硬度为1.63 GPa,弹性模量为78.08 GPa,表现出优良的抗磨减摩性能。     

CNx薄膜的结构、力学性能和摩擦学性能

采用射频磁控溅射方法制备了非晶CNx薄膜。利用纳米硬度计研究了薄膜沉积过程中基体负偏压对薄膜硬度和弹性的影响。利用X光电子能谱分析了CNx薄膜的结构。另外 ,还研究了在微动摩擦实验中振动频率、振幅和载荷对摩擦系数的影响。     

Ag含量对CrN/Ag薄膜微结构、力学及摩擦磨损性能的影响

通过反应磁控溅射法分别沉积了不同Ag含量(Ag/(Ag+Cr)=2.9~21.2%(原子比))的CrN/Ag复合膜,采用能谱仪、X射线衍射仪、纳米压痕仪、扫描电镜、摩擦磨损仪等研究了CrN/Ag复合膜的化学成份、微观结构、力学性能及摩擦磨损性能。结果表明:CrN/Ag薄膜为面心立方结构,由fcc-CrN及fcc-Ag构成。薄膜晶粒尺寸随Ag含量的升高逐渐降低。薄膜硬度随Ag含量的升高先升高后降低,当Ag含量为8.3%时,薄膜硬度最高,其最高值为23 GPa。薄膜硬度受细晶强化与软质Ag相的共同作用。CrN/Ag薄膜平均摩擦系数及磨损率随Ag含量的升高先降低后升高,当Ag含量为8.3%时,薄膜平均摩擦系数与磨损率最小,其最小值分别为0.50和0.68×10~(-8)mm~3。/N·mm。薄膜平均摩擦系数及磨损率主要受低剪切强度Ag含量和H/E值的影响。     

电弧离子镀沉积TiC_x薄膜的结构和性能研究

采用脉冲偏压电弧离子镀沉积系统,在W6Mo5Cr4V2高速钢基体上制备出不同成分的TiCx薄膜。通过扫描电镜、X射线衍射、X射线光电子谱及拉曼光谱对薄膜的表面形貌和微观结构进行分析;采用纳米压痕和摩擦磨损试验来表征薄膜的力学性能。结果表明:所制备的薄膜为富碳TiCx薄膜,富碳成分均以非晶碳形式存在。随着非晶碳组分的增加,薄膜硬度和弹性模量逐渐降低,获得的最高值分别为36GPa和381GPa,同时薄膜的摩擦系数在0.2~0.3之间。     

高速钢上磁控溅射氮化碳薄膜的摩擦学性能研究

采用磁控溅射法在高速钢(HSS)基片上制备了氮化碳(CNx/TiN)复合薄膜,并采用球-盘式摩擦试验法对其摩擦学性能进行了研究.通过分析薄膜的摩擦系数变化曲线,并辅之以薄膜摩擦表面形貌的显微观察分析以及EDS微区成分分析,对薄膜的摩擦学性能进行了表征.结果表明,CNx/TiN复合薄膜与对偶球(Si3N4)之间的摩擦系数约为0.3.具有较好的减摩性能,但复合薄膜的耐磨性能受制备工艺的影响较大.沉积合适的TiN/Ti过渡层可以显著提高薄膜的耐磨性能.薄膜的磨损机理主要为磨粒磨损与黏着磨损以及疲劳磨损相互结合.     

钴合金表面多层碳薄膜的制备及其性能研究

为了改善人工关节的生物摩擦学性能,采用磁过滤直流阴极真空弧源沉积技术在Co-Cr-Mo合金基体表面制备了多层C/C膜。采用拉曼光谱对薄膜的结构进行了表征;利用原子力显微镜观察了多层C/C膜的表面形貌;采用CSEM纳米硬度计测试了多层膜的纳米硬度;在销盘式摩擦磨损试验机上考察了多层膜的生物摩擦学性能。结果表明:多层C/C膜为典型的类金刚石结构,其表面光滑致密,硬度高达52 GPa,它与SiC球在磷酸盐缓冲溶液中的稳定摩擦系数仅为0.012,明显提高了人工关节用材料钴合金的生物摩擦学性能。     

超音速火焰喷涂NiCr-Cr_3C_2涂层的组织结构与摩擦学性能

为进一步提高超音速火焰喷涂NiCr-Cr_3C_2涂层的性能,采用超音速火焰喷涂技术在AISI1045钢基体上制备NiCr-Cr_3C_2涂层。采用扫描电镜、X射线衍射仪分析了涂层的形貌、相结构及化学成分;测试了涂层的显微硬度、弹性模量、结合强度等;采用摩擦磨损试验探究了涂层的摩擦学性能,得出了摩擦系数随时间的变化曲线及涂层的摩擦磨损机理。结果表明:超音速火焰喷涂NiCr-Cr_3C_2涂层晶体结构复杂,含有单晶、纳米晶,还含有少量非晶相,且涂层结构致密,孔隙率低,显微硬度为916 HV3 N,弹性模量为248.671 GPa,结合强度为63 MPa;在不同载荷条件下,涂层的摩擦系数随时间变化趋势大致相同,且载荷越大,摩擦系数越低,磨损体积越大;载荷为20 N时,涂层磨损机制表现为黏着磨损,载荷增大到60 N时,涂层磨损机制过渡到磨粒磨损。     

高速钢上氮化碳薄膜附着力及其影响因素的研究

氮化碳(CNx)薄膜具有优异的力学性能和摩擦学性能,很适合用作耐磨保护涂层及固体润滑剂.采用磁控溅射法在高速钢(HSS)基片上制备了氮化碳薄膜,并以划痕法对其附着力进行了研究.结果表明:有TiN中间层的CNx复合薄膜比无TiN中间层的附着性能有较大的提高.CNx/TiN复合薄膜附着性能较好的主要原因是:对基片严格的清洁处理,采用磁控溅射法对基片施加了合适的负偏压,沉积了合适的中间过渡层;工艺参数合理.     

The effects of annealing temperature on characteristics of UBMS sputtered CNx films for protective coatings

The carbon nitride (CNx) films have been prepared by unbalanced magnetron sputtering (UBMS) at room temperature. The deposited CNx films have been post-annealed at temperatures ranging from 300 °C to 700 °C in increments of 200 °C using rapid thermal annealing (RTA) equipment in vacuum ambient. We investigated the effects of rapid thermal annealing on the structural, surface, and physical properties of CNx films for application of protective coatings. As the result, the increasing annealing temperature led to a decline in physical properties of CNx films such as hardness, elastic modulus, adhesion, frication coefficient, and surface roughness, however it is attributed to the improvement of the residual stress in the film. These results are related to the ordering of sp² bonded clustering and the increase of disordered graphite domain by the desorption of N contents in the films, Specially, high annealing temperature over 700 °C is attributed to the graphitization of film.     

无定型CNx超硬薄膜的生长过程研究

利用直流磁控溅射方法,在高纯石墨衬底上沉积制备碳氮薄膜.借助于SEM对溅射沉积的碳氮薄膜微观形貌进行观察,并对碳氮薄膜的生长过程进行研究.结果表明:沉积所得的碳氮薄膜为无定型结构,且由大量的团簇所组成.在碳氮薄膜的形成过程中,先是在某些局部位置优先形成突起,继而延伸发展成棒状或纤维状结构,并桥联于相邻的CNx团簇间,伴随着这些桥联结构在径向、轴向的扩展,逐渐演变成新的团簇,并毗连成膜;同时,又不断衍生出新的突起,如此反复,实现了碳氮薄膜的持续增厚或生长.     

PEK-C膜层间增韧碳纤维/环氧树脂复合材料的力学性能

为探究热塑性酚酞基聚醚酮（Polyaryletherketone with Cardo,PEK-C）树脂薄膜及膜厚对层间增韧碳纤维/环氧树脂复合材料力学性能的影响,利用浸渍提拉法制备了三种不同厚度（分别约为1 μm、10 μm、30 μm）的PEK-C膜,通过热压成型制备了层间增韧碳纤维/环氧树脂复合材料层合板,对其进行了Ⅰ型层间断裂韧性、冲击后压缩强度、层间剪切及弯曲性能测试,并利用SEM观察微观形貌及AFM扫描微观相图。结果表明:不同PEK-C膜厚增韧碳纤维/环氧树脂复合材料的Ⅰ型层间断裂韧性、冲击后压缩强度及层间剪切强度有不同程度提高,Ⅰ型层间断裂韧性及层间剪切强度以膜厚为10 μm最佳,分别增大了157.17%和17.57%,冲击后压缩强度以膜厚为30 μm最佳,达到了186.67 MPa,这是由于PEK-C与环氧树脂在热压固化过程中形成了双相结构,改善了材料韧性;但弯曲性能持续下降,强度及模量由未增韧的1 551 MPa、106 GPa分别降至30 μm时的965 MPa、79 GPa,这是由于PEK-C树脂扩散进入环氧树脂中,降低了纤维体积分数及材料刚度。      

Grafting of polystyrene on nitrogen-doped multi-walled carbon nanotubes

Polymer grafting of polystyrene (PS) on nitrogen-doped multiwall carbon nanotubes (CNx) was successfully obtained by a "grafting from" technique. The production method involves the immobilization of initiators, using wet chemistry, onto the nanotube surface, followed by an in situ surface-initiated polymerization. The polymer-grafting carbon nanotubes synthesis includes the free radical functionalization of CNx and the "controlled/living" Nitroxide Mediated Radical Polymerization (NMRP). The obtained products were studied using several microscopic techniques as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS). The characterization also includes thermogravimetric analysis (TGA), Raman spectroscopy, infrared spectroscopy, and electron spin resonance (ESR), among others. The analyzed samples were also compared with solutions fabricated by physical blending of the polymer and CNx nanotubes. These results indicate that the nanotube radical functionalization, the chemical grafting, and the polymerization reaction were obtained over CNx when NMRP method was successfully used, giving rise to a uniform PS layer of several nanometers grafted on the outer surface of the CNx nanotubes. Several properties of the PS-grafted CNx nanotubes were also studied. It is shown that the production method leads to a narrower distribution of the external diameters. Moreover, their solubilization in organic solvents is greatly improved. Finally, the dispersion of PS-grafted CNx into a PS matrix is studied to determine the differences in filler dispersion and interfacial adhesion strength, in comparison with nanocomposites elaborated with as-produced CNx.     

硬质合金沉积CNx薄膜及其摩擦性能研究

采用射频反应磁控溅射法在硬质合金(YG8)基片上沉积了CNx和CNx/TiN复合薄膜,并对其进行了后处理.XPS分析CNx薄膜的化学结构表明其中含有N-sp3C和N-sp2C两种结构.摩擦磨损实验研究表明样品具有良好的耐磨性能,样品经后处理后摩擦系数显著降低.     

氮掺杂碳纳米管的无金属催化剂合成和表征

采用爆炸辅助化学气相沉积法, 以碳纳米管(CNTs)作催化剂, 三聚氰胺作碳源和氮源, 无金属催化剂合成出氮掺杂碳纳米管(CN_x). 通过TEM、EDS、Mapping、XPS、Raman和TG测试手段对CN_x进行了表征. 结果表明, CNx具有竹节状结构, 其掺氮量高达17at%, 且氮元素分布均匀. 氮元素以石墨型和吡啶型掺杂在石墨层中, 由于大量氮元素掺杂造成纳米管石墨化程度降低, 抗氧化能力减弱.     

Mechanical characterization of LiPON films using nanoindentation

Nanoindentation has been used to characterize the elastic modulus and hardness of LiPON films ranging in thickness from 1 to 10 μm. Four fully dense, amorphous films were deposited on glass and sapphire substrates with one film annealed at 200 °C for 20 min. The modulus of LiPON is found to be approximately 77 GPa, and argued to be independent of the substrate type, film thickness, and annealing. Based on the numerical analysis of Monroe and Newman, this value may be sufficiently high to mechanically suppress dendrite formation at the lithium/LiPON interface in thin film batteries [1]. Using Sneddon's stiffness equation and assuming the modulus is 77 GPa, the hardness is found to be approximately 3.9 GPa for all but the annealed film. The hardness of the annealed film is approximately 5% higher, at 4.1 GPa. Atomic force microscopy images of the residual hardness impressions confirm the unexpected increase in hardness of the annealed film. Surprisingly, the indentation data also reveal time-dependent behavior in all four films. This indicates that creep may also play a significant role in determining how LiPON responds to complex loading conditions and could be important in relieving stresses as they develop during service.     

Biocompatibility and toxicological studies of carbon nanotubes doped with nitrogen

In this report, we compare the toxicological effects between pure carbon multiwalled nanotubes (MWNTs) and N-doped multiwalled carbon (CNx) nanotubes. Different doses of tubes were administered in various ways to mice: nasal, oral, intratracheal, and intraperitoneal. We have found that when MWNTs were injected into the mice's trachea, the mice could die by dyspnea depending on the MWNTs doses. However, CNx nanotubes never caused the death of any mouse. We always found that CNx nanotubes were far more tolerated by the mice when compared to MWNTs. Extremely high concentrations of CNx nanotubes administrated directly into the mice's trachea only induced granulomatous inflammatory responses. Importantly, all other routes of administration did not induce signs of distress or tissue changes on any treated mouse. We therefore believe that CNx nanotubes are less harmful than MWNTs or SWNTs and might be more advantageous for bioapplications.     

Deformation and fracture behavior of notched and unnotched unidirectional C/C-Mg composite with Young's modulus 520 GPa and tensile strength 1 GPa

Experimental study on tensile fracture behavior of the newly developed C/C-Mg composite, prepared by infiltration of Mg into the pores in the C/C composite heat-treated at 3000°C, was carried out. The volume fraction of the filled Mg was 9–10%. The composite had a specific density 2.1, Young's modulus 520 GPa and Poisson's ratio 0.26. The average tensile strength measured for the specimen with a nominal width 8 mm, gage length 40 mm and thickness 1 mm was 1 GPa. The Young's modulus was improved from 450 to 520 GPa and the strength from 0.9 to 1.0 GPa by Mg-infiltration. The specific Young's modulus and specific strength based on the average measured values were 2.5 × 10⁷ m and 5 × 10⁴ m, respectively, showing high potential as light-weight, stiff and strong structural material. The strength distribution of the composite was described by the two-parameter Weibull distribution function with a shape parameter 7.6 and scale parameter 1060 MPa. Prior to the overall fracture of the composite, the longitudinal cracking arose at the notch tip, due to which the notch tip was blunted and the ligament portion behaved like an unnotched specimen. As a result, the notched strength could be described by the net stress criterion. The apparent critical energy release rate at formation of the longitudinal crack was around 70–90 J/m².