类金刚石碳膜(DLC)的制备和性能及其在工具和模具中的应用

类金刚石碳膜（DLC）有极优良的性能，与金刚石膜（DF）类似。已有很多的应用。简介了DLC膜的结构，性能，实用的制备方法及其在工具和模具等领域中的应用。     

脉冲磁过滤阴极弧技术制备类金刚石薄膜研究

介绍了弯曲电弧磁过滤设备,并利用脉冲磁过滤阴极真空电弧沉积技术,在高速钢基体上制备了DLC膜.对制得的DLC薄膜表面形貌、Raman光谱及纳米硬度和弹性模量等进行了测试.结果表明,脉冲磁过滤阴极电弧法制备的DLC膜具有优良的性能.拉曼光谱分析显示,制得的薄膜为非晶结构,具有明显的sp2和sp3键杂化结构,符合DLC膜的特征,基体负偏压为50 V时,沉积的DLC膜Raman光谱的ID/IG值最小,sp3键含量最高,纳米硬度和弹性模量值达到最高,分别为29.94 GPa和333.9 GPa.     

氮化硅陶瓷表面DLC膜的制备及摩擦性能研究

利用等离子体基离子注入与沉积技术,在氮化硅陶瓷片表面制备200～400nm的类金刚石碳膜。测试薄膜的厚度、表面形貌、结构、膜基结合力,利用球盘试验机考察DLC膜的摩擦性能。结果表明:沉积薄膜均匀光滑;薄膜的硬度和弹性模量与基体差异较小,膜基结合力强;DLC膜具有较低的摩擦因数,抗磨性能优异。     

脉冲偏压对PECVD制备DLC薄膜的结构及性能的影响

在不锈钢基材表面利用等离子体增强化学气相沉积技术(PECVD)改变脉冲偏压制备不同结构类金刚石薄膜(DLC)。分别采用表面轮廓仪、扫描电镜、拉曼光谱及电子探针分析薄膜的表面粗糙度、断面形貌、薄膜结构及成分,采用纳米压痕仪及划痕仪测试薄膜的纳米硬度、弹性模量和膜基结合力,采用球盘摩擦试验机测试薄膜在大气环境中的摩擦学性能。结果表明:脉冲偏压显著影响PECVD制备的DLC薄膜的表面粗糙度、微观形貌、膜基结合力、纳米硬度及摩擦学性能;随偏压的增大,DLC薄膜的表面粗糙度,摩擦因数及磨损量都先减小后增大,而膜基结合力则先增大后减小。其中2.0 k V偏压制备的DLC薄膜具有最强的膜基结合力,而1.6 k V偏压制备的DLC薄膜具有最低的表面粗糙度、最高的硬度和最优的减摩耐磨性能。     

磁控溅射沉积TiB_2/DLC纳米多层膜的结构及其机械性能研究

采用非平衡磁控溅射系统在P(100)硅片和304不锈钢基底上制备TiB_2/DLC纳米多层膜。利用FESEM、TEM、XRD和AFM观察多层膜的微观结构和表面形貌;利用纳米压痕仪、维氏硬度计和CSM球-盘摩擦磨损试验机考察TiB_2靶电流对多层膜的机械性能和摩擦学性能的影响。结果表明:TiB_2/DLC多层膜具有良好的多层调制结构,多层膜沿TiB_2(101)晶向择优生长;多层膜的表面粗糙度随着TiB_2靶电流增加而增加;多层膜中的大量异质界面能显著提高薄膜的硬度及韧性,而且当TiB_2靶电流为2.0 A时,多层膜的硬度约为单层DLC薄膜的两倍;多层膜中具有硬质TiB_2层和软质DLC层的交替结构,在摩擦过程中,硬层TiB_2起到良好的承载作用,软层DLC起到良好的润滑作用,使多层膜具有比单层DLC薄膜更低的摩擦因数。     

硬质合金表面SiC/DLC涂层组织和性能研究

DLC涂层可有效降低硬质合金刀具切削过程中的摩擦系数和切削力,使用等离子增强化学气相沉积的方法在硬质合金(YG8)基体和Si(100)表面沉积Si C/DLC涂层,其中,C_2H_2和H_2流量比分别为3∶0、2∶1、1∶1、1∶2和1∶3。测试了Si(100)表面Si C/DLC涂层的厚度、生长形貌、sp~3键的含量,并对硬质合金表面Si C/DLC涂层的硬度、膜基结合力和摩擦系数进行了全面分析。结果表明,Si C/DLC涂层均为非晶态形貌,随着H_2流量的增加,涂层厚度不断下降;当C_2H_2/H_2=1∶1时,涂层的sp~3键的比例最大,并达到41.0%,且具有较低的摩擦系数;涂层的硬度和弹性模量随着H2流量的增加而降低;C_2H_2/H_2=1∶3时,涂层表现出最佳的膜基结合力。     

非平衡磁控溅射制备Cr掺杂DLC复合薄膜的高温摩擦学性能

元素掺杂是提升DLC薄膜摩擦学性能和耐温性能的重要途径。采用直流磁控溅射技术在304不锈钢基体表面沉积了含氢DLC薄膜,同时利用射频磁控溅射技术完成Cr元素的掺杂,研究Cr元素掺杂对DLC薄膜的力学性能及摩擦学性能的影响。采用纳米压痕仪测试薄膜硬度并利用划痕试验测试膜基结合力,采用拉曼光谱分析薄膜sp²和sp³键含量的变化和转移膜的生成。采用UMT多功能摩擦磨损试验机评价薄膜在常温和高温环境下的摩擦磨损性能,并利用扫描电镜观察磨损表面,分析其磨损机制。结果表明,Cr元素掺杂会显著提高薄膜的膜基结合力,但会使薄膜硬度有一定的下降。常温摩擦学性能测试显示,DLC薄膜的摩擦因数随着Cr含量的增加呈现出先下降后上升的趋势,在Cr质量分数为3.34%时达到最低;但薄膜的磨损率随Cr含量的增加略有升高。高温摩擦学性能测试表明,Cr元素掺杂显著改善了DLC薄膜的高温摩擦学性能,未掺杂的DLC在150℃以上摩擦时会失效,Cr元素掺杂使薄膜在250℃下也能保持较低的摩擦因数和较长的抗磨寿命。Cr元素的加入能够提高DLC薄膜的膜基结合力,降低摩擦因数,并提高薄膜...     

用AFM压痕技术定量介观硬度的方法研究

用原子力显微镜(AFM)纳米压痕方法结合扫描力显微镜技术，表征类金刚石(DLC)膜，金块Au，单晶硅Si的纳米硬度。用能量密度理论解释基于AFM压痕技术测定纳米硬度的机理，给出AFM纳米压痕的能量平衡方程。对DLC膜，金块，单晶硅进行纳米压痕试验，表明在同样载荷下，不同材料的压痕深度是不相同的。DLC膜具有较高的抗压性能，Si其次，Au的抗压性能最低。通过曲线拟合技术，定量给出金块的纳米硬度分析模型：H=(2．83／Df) 2．86。     

飞秒脉冲激光沉积类金刚石膜实验研究

期望用类金刚石膜作为硅的红外保护/增透膜,采用波长为800nm,脉宽50fs,重复频率1KH z的T i:Sapph ire飞秒激光器及石墨靶材在单晶S i片上沉积了约0.7μm~1μm厚的类金刚石膜(d iam ond-like carbon film s,DLC),获得了光滑致密,硬度显著提高,红外透过率有一定增加的样品。通过对薄膜拉曼光谱和X射线光电子能谱等的测试,发现单脉冲能量在0.4m J~1.6m J范围内变动时,单脉冲能量0.8m J获得的类金刚石膜综合性能最佳,其对应的焦斑功率密度计算值为1.4×1014W/cm2。     

采用End-Hall源沉积类金刚石膜

介绍了两种普遍采用的类金刚石(DLC)膜沉积方法。在此基础上叙述了采用End-H all源沉积DLC膜的方法,在简单说明其工作原理的同时给出了实验的各项技术参数;通过对实验结果和DLC膜样品的分析,可看出用End-H all源沉积方式能够消除RFCVD沉积方式所带来的边缘效应。     

Friction and Wear of Various DLC Films in Water and Air Environments

Three types of diamond-like carbon (DLC) films, pure DLC, F-containing DLC, and a Si-containing DLC film, were deposited on a WC–Co substrate by a plasma-enhanced CVD technique. Friction and wear properties were determined using a ball-on-plate type reciprocating friction tester in water, comparing the water results to those in ambient air. The friction coefficient of DLC and F–DLC films in water was considerably lower than that in air. With Si–DLC, the friction was almost the same level in both water and air, and was less than 0.1. The specific wear rate of films in water was much smaller than that in air and varied around the low level of 10^–8 mm³/Nm in water, The mating ball wear was also less than 10^–8 mm³/Nm. With DLC and F–DLC films, the transferred amount of material on the friction surface of a mating ball was larger in a water environment than that in air. With a Si–DLC film, the difference in the transferred amount when exposed to either the water or air environment was negligible.     

An overview on the tribological behavior of diamond-like carbon in technical and medical applications

Diamond-like carbon (DLC) coatings are a class of materials and, depending on the deposition conditions and the tribological system, different outstanding tribological properties can be obtained. The most important subclasses of DLC are hydrogenated amorphous carbon (a-C:H) and hydrogen free tetrahedral amorphous carbon (ta-C). When DLC slides against a metal, the formation of the so-called transfer layer on the metallic counterpart can protect the metal from further wear. Adhesion and cohesion of this transfer layer is a critical issue and is also influenced by the environmental atmosphere including the relative humidity. When DLC is running against a hard and chemically inert counterface, such as sapphire, the formation of a transfer layer is not observed but low wear is still obtained. This is attributed to the lubricating properties of the graphitic wear residues. Due to its unique combination of properties, DLC is already used in different industrial applications such as magnetic storage media, diesel injection pumps, sliding bearings, car valve rockers, gears, tappets of racing motorcycles, laser barcode scanner windows in supermarkets, VCR head drums, textile industry parts, motor cycle forks, razor blades, etc. In medical applications, i.e. the coating of load bearing joints that slide against ultra high molecular weight polyethylene (UHMWPE), the different in vitro experiments apparently showed contradicting results, mainly due to the different experimental setups and especially the different liquids used as lubricants. However, when DLC slides against DLC in medical applications low wear rates could be demonstrated in different in vitro tests.     

Mechanical properties of thin carbon overcoats

Components used in magnetic storage systems (hard discs, tape heads and drums) are often very small and lightweight, and operate under very low loads (of the order of a few micrograms to a few milligrams). As a result, friction and wear processes occur on a nanometre scale and conventional tribological test methods and assessment tools are usually not appropriate. Furthermore, the assessment of the mechanical properties of the coatings or surface treatments used to protect these components from wear is complicated by the low thickness of the layers generally used. This paper details the problems associated with the assessment of the mechanical properties of thin diamond-like carbon coatings used to protect hard discs, tape heads and air bearings. Whereas thick coatings (>1 μm) are relatively easy to assess, even if the substrate has a low hardness and offers little support to the coating, there are many more problems when it comes to measuring the properties of the 5–10 nm layer on a hard disc. In many cases there is no plastic deformation of the coating which merely flexes and bends into the hole produced by plastic deformation of the substrate. Deformation of the coating is then limited to localised plasticity at the indenter edges, and/or fracture along the same edges and at the edge of the contact. The limits for use of Nanoindentation to assess the plasticity of the coating are discussed for such cases.     

Development of diamond-like carbon fibre wheel

The first author invented a unique diamond-like carbon (DLC) grinding wheel, in which the DLC fibres were made by rolling Al sheets coated with DLC films and aligned normally to the grinding wheel surface by laminating Al sheets together with DLC fibres [K. Yamaguchi, Y. Wei, M. Takeuchi, Development of DLC fibre grinding wheel, in: Proceedings of the Vernal Meeting of the JSPE, Tokyo, 16–18 March 1999, p. 260]. In this paper, the formation process of DLC fibres and the fabrication process of a DLC fibre wheel were investigated. Many grinding experiments were also carried out on a precision NC plane milling machine using a newly developed DLC wheel. Grinding of specimens of silicon wafers, optical glasses, quartz, granites and hardened die-steel SKD11 demonstrated the capabilities to nanometer surface finish. A smooth surface with a roughness value of Ra 2.5 nm (Ry 26 nm) was achieved.     

Characterisation of DLC coating adherence by scratch testing

In order to characterize the adherence of DLC coatings (Diamond Like Carbon), scratch testing was performed on a unit equipped with sensors for normal and tangential forces, and an acoustic detector to detect the nucleation and the propagation of cracks. The system is also equipped with a microscope permitting observation of each event on the scratch according to the friction tangential force signal or the acoustic signal. The local microscopic observation allows identification of the damage with respect to the normal load. The test was performed with a Rockwell C indenter at the relative displacement speed, v=10 mm/min under a progressive normal load from 5 to 55 N.Coating failure appears in various modes, particularly the following: propagation of the cracks along the longitudinal edges of the scratch; propagation in front of the indenter; rupture along the maximum principal stress lines; and, detachment in the subsurface by shearing of the coating. The microscopic analysis of the evolution of the scratch under a progressive normal load permits identification of the various traces and the damage mechanisms of the coating.In this study, experimental results are shown for the scratch tests on bulk glass and DLC coating. Various modes of crack initiation, damage and rupture of these materials according to the critical normal load are presented. The analysis of the contact stress field distribution in bulk glass enables identification of the crack initiation and its propagation in the coating.     

Oscillating Tangential Forces on Cylindrical Specimens in Contact at Displacements within the Region of No Gross Slip

The effects of oscillating tangential forces on cylindrical specimens at relative displacements within the no-gross-slip region have been studied experimentally. It is shown that within the no-gross-slip region there is a well-defined region at the onset of tangential displacement within which a primarily elastic deformation is indicated. Energy dissipation studies indicate that in this region the behavior is essentially visco-elastic, confirming the results of published work. This “limit of elastic behavior” has been found and measured for a number of metallic and non-metallic materials including diamond and plastics. At amplitudes below this limit no discernable wear is observed, even after millions of cycles of rubbing. However, at larger amplitudes, wear is rapid and characteristic of fretting corrosion, especially above the gross slip amplitude. Values of elastic tangential compliance at the limit of elastic behavior are determined which are in agreement with published theoretical work.     

Boundary lubrication mechanisms of carbon coatings by MoDTC and ZDDP additives

Fuel economy and reduction of harmful elements in lubricants are becoming important issues in the automotive industry. An approach to respond to these requirements is the potential use of low friction coatings in engine components exposed to boundary lubrication conditions. Diamond-like-carbon (DLC) coatings present a wide range of tribological behavior, including friction coefficients in ultra-high vacuum below 0.02. The engine oil environment which provides similar favourable air free conditions might lead to such low friction levels.In this work, the friction and wear properties of DLC coatings in boundary lubrication conditions have been investigated as a function of the hydrogen content in the carbon coating. Their interaction with ZDDP which is the exclusive antiwear agent in most automotive lubrication blends and friction-modifier additive MoDTC has been studied. Hydrogenated DLC coatings can be better lubricated in the presence of the friction-modifier additive MoDTC through the formation of MoS₂ solid lubricant material than can non-hydrogenated DLC. In contrast, the antiwear additive ZDDP does not significantly affect the wear behavior of DLC coatings. The good tribological performances of the DLC coatings suggest that they can contribute to reduce friction and wear in the engine, and so permit the significant decrease of additive concentration.     

Self-assembled monolayer on diamond-like carbon surface: formation and friction measurements

We have investigated self-assembled monolayers (SAMs) of heptadecafluoro-1,1,2,2-tetradecyltrietoxysilane (FTE) on diamond-like carbon (DLC) surfaces formed by a simple immersing process. SAM formation on DLC surfaces was verified by contact angle measurements, ellipsometry and X-ray photoelectron spectroscopy (XPS). Water and hexadecane contact angles increased gradually with immersing time and saturated at about 110 and 70 degrees, respectively. Ellipsometric measurements showed that the film thickness was 1.4 to 1.6 nm, which corresponded reasonably to the thickness of FTE monolayer. XPS data showed the presence of FTE molecules on the DLC surface. These results ensured the SAM formation of FTE molecules on the DLC surface.We further measured and compared the friction of unlubricated, SAM coated and 2 nm thick perfluoropolyether (PFPE) coated DLC surfaces using lateral force microscopy (LFM) as functions of the applied load and the sliding velocity. The SAM coated DLC surfaces showed lower friction than the unlubricated DLC surfaces and the friction coefficient decreased by about 15% compared to the unlubricated DLC surfaces. Scratch tests revealed that the critical load of the DLC film increased due to the SAM deposition. These results are attributed to the hydrophobic nature of the SAM coated surface. On the other hand, even though the water contact angle of the SAM coated surface was larger than the 2 nm thick PFPE coated surface, the friction of the SAM coated surface was larger than that of the PFPE coated surface. Also, the critical load of the SAM coated DLC surface in scratch test was lower than the PFPE coated surface. These results indicate that the hydrophobic nature of the surface is not the only factor which determines the friction characteristics in the nano-lubricating system, and it is attributed to the mobile characteristic of PFPE lubricant.     

Tribological performance of a DLC coating in combination with water-based lubricants

The tribological behaviour in water-based environments has been studied for a tungsten carbide-doped DLC coating (WC/C) deposited by physical vapour deposition (PVD) on bearing steel. Several tribological test equipments have been used to characterise the wear rate, coefficient of friction and resistance to seizure of the coated system, in comparison with uncoated bearing steel surfaces. It was observed that the wear was decreased and the coefficient of friction reduced in pin-on-disc measurements for poor lubricants. Further, the resistance to seizure in the four-ball method was improved by a factor of approximately three. Results from Reichert measurements showed a decreased wear rate and also a very pronounced running-in behaviour of the coating for some water-based lubricants. It has been shown that the performance of tribological systems with water-based lubricants can be significantly improved with this type of DLC coating.