钛过渡层与硬质合金基体表面结合状况对金刚石薄膜附着力的影响

以WC-6％Co为基体,采用磁控溅射法,在原始试样、酸腐蚀试样以及酸蚀后进行氢等离子体脱碳处理的试样上制备Ti过渡层,然后碳化过渡层为TiC。在热丝化学气相沉积装置中,制备金刚石薄膜。研究三种不同试样上的金刚石薄膜与基体的附着力。结果表明,在原始试样上的金刚石薄膜在冷却过程中自动脱落;在经等离子体处理后的试样上,金刚石薄膜与基体间附着力高于在经酸蚀处理的试样上的金刚石薄膜与基体附着力。造成这种现象的主要原因可能是等离子体脱碳还原处理降低WC晶粒表面能,增强Ti与WC间的结合强度,导致TiC过渡层与WC基体结合强度增加,从而增加金刚石薄膜附着力。     

Adherent nanocrystalline diamond coatings deposited on Ti substrate at moderate temperatures

Microwave plasma enhanced CVD deposition of adherent nanocrystalline diamond coating on pure Ti substrate was studied at a moderate temperature and with a wide range of CH₄ concentrations. Under low CH₄ concentrations, the adhesion failure of diamond coatings is primarily observed at the titanium carbide–substrate interface. Under higher CH₄ concentrations, the diamond coating debonding occurs both at the diamond–carbide interface and carbide–substrate interface. On the whole, the nucleation density, nucleation rate and adhesion strength of diamond coatings grown on Ti substrate are enhanced with increasing CH₄ concentrations. Synchrotron X-ray Laue micro-beam diffraction characterization of the underlying Ti substrate reveals that a microstructure coarsening occurs after hydrogen plasma etching, whereas the hydrogen penetration is effectively mitigated under super high CH₄ concentrations.     

Triode plasma nitriding and PVD coating: A successful pre-treatment combination to improve the wear resistance of DLC coatings on Ti6Al4V alloy

Diamond-like carbon (DLC) coatings have found great applicability in the automotive industry because of their low friction coefficient and high wear resistance. Nevertheless, their tribological performance can be greatly reduced on soft substrates such as titanium alloys. The hard DLC coating cannot usually follow elastic and plastic deformation of the substrate without failing. In order to overcome this property mismatch between hard coating and soft substrate, triode plasma nitriding was applied as a pre-treatment to improve the mechanical properties of the Ti6Al4V alloy and further enhance the load support for the DLC coating. DLC and multilayered TiN/DLC, CrN/DLC CrAlN/DLC coatings were deposited onto “standard” and plasma nitrided Ti6Al4V substrates. Triode plasma nitriding increased the load-bearing capacity of the coating/substrate system, as higher critical adhesion loads were recorded for DLC coatings on plasma nitrided Ti6Al4V substrates. This treatment also reduced the wear rate of the DLC coating/substrate. Further load support and lower wear rates were achieved by using TiN, CrN and CrAlN as intermediate layers on plasma nitrided Ti6Al4V substrates.     

Effects of Cu and Cu/Ti interlayer on adhesion of diamond film

Diamond film were deposited on the cemented WC + 6% Co substrates by a microwave plasma chemical vapor deposition (CVD) system. The effects of Cu and Cu/Ti as interlayer on adhesion of diamond film were investigated. The surface morphology and composition of the film and microstructure of film/substrate interface were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and Raman spectrometer, respectively. The adhesion of diamond film was evaluated by indentation adhesion testing. The results show that Cu/Ti would be a suitable interlayer system to improve film adhesion. It was considered that Cu atoms replaced most voids left by leached Co, recovered the surface strength and toughness, and inhibited the diffusion of Co to the substrate surface. Ti atoms act as promoter for diamond nucleation, and the formation of TiC enhanced the adhesion of diamond film. Furthermore, Cu/Ti interlayer system restrained the growth of diamond grain and promoted the formation of nano-crystalline, which increased the contact area of the film/substrate interface.     

Effect of pretreatment, seeding and interlayer on nucleation and growth of HFCVD diamond films on cemented carbide tools

The direct deposition of diamond on carbide tools is difficult because formation of graphitization and thus leading to poor adhesion, due to presence of cobalt on the surface. Various methods were adopted to suppress the effect of cobalt during deposition. One of them was by putting an interlayer. In this study, carbide substrates with coatings of Ti, TiN and TiC were used. Ti coating has a strong tendency to form intermediate carbide leading to the highest nucleation density of diamond. A comparison was made on nucleation and growth of diamond crystals on various interlayers by hot filament CVD method. At the same time, the variations of diamond film growth morphology have been studied on unseeded and seeded carbide inserts. The SEM pictures revealed that among interlayer, Ti coating gave highest nucleation density compared to TiN and TiC coatings. At the same time, diamond seeded inserts, pretreated by Treat 1 [HCl + HNO₃ + H₂O (1:1:1)] for 15 min ultrasonically resulted in the highest nucleation density, compared to Treat 2 [K₃[Fe(CN)₆] + KOH + H₂O] solution in (1:1:10) for 15 min, at constant process parameters.     

Growth of Free-standing Diamond Films on Graphite Substrates with Ti Interlayers

DIAMOND has many remarkable chemical andphysical properties,such as extreme hardness,highthermal conductivity,high electrical resistively andexcellent optical transparency and so on.For diamond,approximately5.5ev is required to excite an electronfrom the valence band to the conduction band,compared with1.1ev for Si and0.7ev for Ge m.Therefore,Diamond is a wide band gap material.Furthermore,due to the high vibration energy of carbonatoms in diamond,the frequency of infrared absorptionis abn…     

Effects of Ti- and Zr-based interlayer coatings on hot-filament chemical vapor deposition of diamond on high-speed steel

The prospect of obtaining good adhesion of diamond films onto steel substrates is highly exciting because the achievement of this objective will open up numerous new applications in industry. However, a major problem with depositing diamond onto steel is high diffusion of carbon into steel at chemical vapor deposition (CVD) temperatures leading to a very low nucleation density and cementite (Fe₃C) formation. Therefore, the study of the nucleation and growth processes is timely and will yield data that can be utilized to get a better understanding of how adhesion can be improved. This work focuses on the adhesion of thin diamond films onto high speed steel previously coated with various interlayers such as ZrN, ZrC, TiC, and TiC/Ti(C,N)/TiN. The role of seeding on nucleation density and the effect of diamond film thickness on stress development and adhesion has been investigated using scanning electron microscopy (SEM), x-ray diffraction (XRD), and Raman spectroscopy (RS). The main emphasis in this study lies with TiC, which for the first time proved to be a suitable layer for diamond CVD on high-speed steel (HSS). In fact, different from other interlayer materials investigated, no delamination was observed after 3 h of CVD at 650 °C when TiC was used. Nevertheless, the increase of diamond film thickness on TiC-coated HSS substrates led to delamination of small areas. This occurrence suggests that there was a distribution of adhesive toughness values at the diamond/TiC interface with the stress development being dependent on film thickness. This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in St. Paul, MN.     

Influence of interlayers on corrosion resistance of diamond-like carbon coating on magnesium alloy

Diamond-like carbon coating (DLC) was deposited on AZ31 magnesium alloy by ion beam deposition technique in this study. A columnar Cr layer with a (110) preferred texture and a columnar CrN layer with a (111) preferred texture were applied as interlayers in the DLC coating/AZ31 substrate systems. The addition of these interlayers improved the adhesion between coating and substrate effectively, but did not enhance the corrosion resistance of the DLC/AZ31 systems due to the formation of galvanic cell between substrate and interlayer in the region of through-thickness defects in 3.5 wt.% NaCl solution. In addition, the effect of bias voltage on the corrosion resistance of CrN/Cr coatings on magnesium alloys was investigated. Although the application of bias voltage induced the coating denser, it was still difficult for CrN/Cr coating to reduce the corrosion current density of AZ31 due to the large difference between coating and substrate in galvanic series.     

A critical review of diamond like carbon coating for wear resistance applications

In recent years innovation in carbon based materials have encouraged both researchers as well as industrialists to develop materials/composites with improved tribological properties. Researchers have been fascinated to develop diamond like carbon (DLC) or carbon nanotubes (CNTs) reinforced coatings to their good corrosion resistance, excellent wear resistance, good adhesion strength, and self -lubricious nature. The present review article is mainly focused on various techniques employed in order to process DLC/CNTs coatings as well as provide a summary of DLC/CNTs deposition on different substrates. The present study includes major types, properties and tribological behavior of carbon based materials and mechanisms involved in coating deposition. The study also discusses that deposition of DLC/CNTs coatings on the substrate materials enhances the wear, corrosion and mechanical properties of the substrate.     

热丝辐射距离和W-C梯度过渡层对高速钢基体气相生长的影响

使用反应磁控溅射技术在W18Cr4V高速钢基体表面制备W-C梯度过渡层(WCGC),采用热丝化学沉积法(HFCVD),以甲烷和氢气为反应气体,在基体表面生长金刚石膜。采用场发射扫描电子显微镜(FE-SEM)、X射线衍射仪(XRD)和激光拉曼光谱(Raman)对W-C过渡层和金刚石膜进行检测分析,研究热丝辐射距离和沉积气压对WCGC与金刚石膜的的影响。结果表明:热丝辐射距离对金刚石薄膜和WCGC均有较大影响;WCGC过渡层能够在一定热丝辐射范围内降低Fe在金刚石膜沉积过程的负面影响,有效提高金刚石的形核率,在基体表面得到连续致密的金刚石膜。     

Enhancing the adhesion of diamond films on cobalt-cemented tungsten carbide substrate using tungsten particles via MPCVD system

To increase the adhesion of diamond films and avoid the negative effects of using cobalt, previous treatments have employed tungsten particles to cover the surface of the 6 wt.% cobalt-cemented tungsten carbide (WC-Co) substrate. The surface of the tungsten particles is transformed into W₂C and WC, which attracts and traps carbon. Through the process of nucleation, the carbon forms around the tungsten particles, thereby satisfying the conditions necessary for the formation of diamond film. Using Raman spectroscopy, we determined that diamond films of good quality with excellent adhesive properties and a hardness level as high as 27.78 GPa could be produced following pretreatment with 2.0 μm tungsten particles. Rockwell indentation tests indicate that addition of tungsten particles promotes the interfacial adhesion of diamond films with WC-Co substrates. We determined that using smaller tungsten particles decreased the number of gaps and cavities on the surface of the substrate, thereby enhancing the adhesion of the diamond film.     

梯度基体温度法和反应溅射TiC过渡层对钛合金基体沉积金刚石薄膜的影响

以H2和CH4作为反应气体,采用热丝化学气相沉积法(HFCVD)在钛合金(Ti6Al4V)平板基体上制备金刚石薄膜,利用扫描电镜(SEM)、X射线衍射仪(XRD)、激光拉曼光谱(Raman)和洛氏硬度仪分析薄膜的表面形貌、结构、成分和附着性能,研究了高温形核-低温生长的梯度降温法对原始钛合金和反应磁控溅射TiC过渡层的钛合金表面沉积金刚石薄膜的影响。结果表明:原始基体区和TiC过渡层区沉积的金刚石薄膜平均尺寸分别为0.77μm和0.75μm,薄膜内应力分别为-5.85GPa和-4.14GPa,TiC层的引入可以有效提高金刚石的形核密度和晶粒尺寸的均匀性,并减少薄膜残余应力;高温形核-低温生长的梯度降温法可以有效提高金刚石的形核密度和质量,并提高原始基体上沉积金刚石薄膜的附着性能。     

Plasma immersion ion implantation induced improvements of mechanical properties, wear resistance, and adhesion of diamond-like carbon films deposited on tool steel

Nitrogen-rich layers are formed on the surface of JIS-SKH51 tool steel substrates using the plasma immersion ion implantation (PIII) technique. An unbalanced magnetron sputtering (UBMS) system is then used to coat the steel substrates with diamond-like carbon (DLC) films of various thicknesses. The adhesive strength and wear resistance of the DLC films are then examined by performing nanoscratch and nanowear tests. Finally, the microstructures of the DLC films are analyzed using TEM and Raman spectroscopy. The nanoindentation test results show that the PIII treatment yields an effective improvement in both the hardness and the Young's modulus of the SKH51 substrates. Moreover, cross-sectional observations show that the implantation depth and microstructure of the nitrogen-rich surface layer are dependent on the nitrogen/hydrogen flow ratio used in the PIII process. The nanoscratch test results show that the PIII treatment improves the adhesion of the DLC film to the steel substrate. Furthermore, the Raman spectroscopy results indicate that the use of hydrogen in the PIII process limits the increase in the I(D)/I(G) ratio by increasing the DLC film thickness. Finally, the nanowear test results show that the deposition of a DLC coating with a sufficient thickness yields a significant improvement in the wear resistance of the steel substrate.     

采用WC过渡层增加金刚石薄膜附着力的研究

在微波等离子体化学气相沉积装置中，以WC-8％Co为基体，采用氢等离子体脱碳、磁控溅射镀W、碳化等方法，制备了微晶WC过渡层。研究了金刚石薄膜与基体的附着力。结果表明，表面脱碳后再镀W膜，W填充了氢等离子体脱碳时刀具表面因钴蒸发而留下的空洞，形成过渡层，在随后的碳化中和基体WC连接较为紧密，能增加金刚石薄膜与基体附着力，克服单纯的氢等离子体脱碳还原法降低刀具基体硬度、不能完全消除钴的有害影响的缺点。     

CVD金刚石涂层硬质合金衬底预处理新方法研究

本文研究了甲醇预处理方法对硬质合金衬底表面抑制Co催石墨化作用。将甲醇预处理方法融入到传统的两步处理方法中,提出了新的两步预处理方法,通过电镜和EDX等手段对预处理后的衬底表面形貌、成分进行了分析。采用偏压增强热丝CVD(HFCVD)法,在预处理后的衬底表面成功沉积了金刚石薄膜。并以制做钻头为例,验证了两步法对复杂形状衬底的预处理及金刚石薄膜制备效果。研究结果表明:采用甲醇预处理方法能够有效抑制Co对金刚石薄膜的不利影响,新的两步预处理方法既能保证金刚石薄膜与衬底之间的附着强度,又非常适用于复杂形状整体式回转硬质合金刀具、拉拔模具等衬底,对于拓展金刚石涂层在涂层刀具领域的应用具有一定的参考作用。     

压痕法研究镶嵌结构界面金刚石膜粘附性能

在铜基体上沉积Cu(Cr)-diamond复合过渡层,用热丝CVD法在复合过渡层上沉积出金刚石膜。用压痕法对沉积的金刚石膜/基结合性能进行了研究。结果表明,在Cu-diamond上沉积的金刚石膜,用147 N压痕时压痕边缘出现大面积崩落,并在基体表面留下被拔出的金刚石凹坑;在Cu-diamond中掺入微量Cr,压痕边缘只形成环形裂纹,增大压痕载荷至441 N,环形裂纹区域增大,并出现部分崩落,崩落区域有被切断的金刚石残留。在Cu-diamond复合层中掺入微量Cr能显著提高金刚石膜/基结合力。     

COMPARISON OF SURFACE PROPERTIES OF Ti-6Al-4V COATED WITH TITANIUM NITRIDE, TiN+TiC+Ti(C,N)/DLC, TiN/DLC AND TiC/DLC FILMS BY PLASMA-BASED ION IMPLANTATION

1. IlltroductionThe high yield strength and toughness, moderate modules, low density, good corrosionresistance and exceptional biocompatibility of Ti-6Al--4V alloy have made it increasinglypopular in industrial and medical application. But the alloy does not have enough wearresistance, and so is restricted in surface, particularly tribological applications to a certain e.tent[1--2]. It has been demonstrated that plasma-based ion implalltation (PBll), anew cost-effective technique for improvi…     

DLC、TiN涂层对TC4钛合金抗砂尘冲蚀性能的影响

为提高TC4钛合金的抗砂尘冲蚀性能,采用金属蒸汽真空弧(MEVVA)离子源注入与磁过滤真空阴极弧(FCVA)沉积复合技术、磁控溅射技术在TC4钛合金表面制备DLC、TiN涂层。采用SEM、Raman、XRD、纳米压痕仪和划痕仪等方法对涂层的物相结构、硬度、弹性模量以及与基体的结合力进行表征。在冲蚀试验平台上考核试样在不同入射角度条件下的抗砂尘冲蚀性能。结果表明:DLC涂层表面结构致密,含有大量sp3键,硬度为62.1 GPa,弹性模量为391.64 GPa,结合力达80.4 N;TiN涂层表面存在许多熔滴颗粒及空穴,硬度为22.72 GPa,弹性模量为383.18 GPa,结合力达34.7 N。30°冲蚀条件下,涂层主要是通过提高基体表面硬度来抵抗砂尘粒子的微切削作用,从而提高TC4钛合金的抗砂尘冲蚀性能。90°冲蚀条件下,涂层通过延缓基体的塑性变形来实现TC4钛合金抗砂尘冲蚀性能的提高。     

Synthesis and Characterization of Quenched and Crystalline Phases: Q-Carbon,Q-BN,Diamond and Phase-Pure c-BN

We report the synthesis and characterization of quenched (Q-carbon and Q-BN) and crystalline (diamond and c-BN) phases using a non-equilibrium technique. These phases are formed as a result of the melting and subsequent quenching of amorphous carbon and nanocrystalline h-BN in a super undercooled state by using high-power nanosecond laser pulses. Pulsed laser annealing also leads to the formation of nanoneedles, microneedles and single-crystal thin films of diamond and c-BN. This formation is dependent on the nucleation and growth times, which are controlled by laser energy density and thermal conductivities of substrate and as-deposited thin film. The diamond nuclei present in the Q-carbon structure (~ 80% sp³) can also be grown to larger sizes using the equilibrium hot filament chemical vapor deposition process. The texture of diamond and c-BN crystals is 〈111〉 under epitaxial growth and 〈110〉 under rapid unseeded crystallization. Our nanosecond laser processing opens up a roadmap to the fabrication of novel phases on heat-sensitive substrates.     

WC—8．0％Co基底上微波等离子化学气相沉积金刚石膜

了基片预处理和工艺参数对微波等离子化学气相沉积金刚石涂层WC－8．0％Co刀质量的影响,研究了提高成核密度和沉积速率的方法,用SEM,XRD,激光Raman光谱分析了金刚石涂层质量,用切削试验检测金刚石涂层与刀具基底的附着情况,结果表明,在1：3的稀盐酸中酸洗15min后氨水浸泡10min的基片处理方法能有效地抑制金属钴的溢出,从而提高金刚石涂层的质量,并且使刀具使用寿命提高10倍以上。