采用热丝CVD法在多种基材上沉积金刚石薄膜

热丝法是一种比较成熟的气相合成金刚石膜的方法,其其它方法比较,热丝法在工艺参数对金刚石薄膜的结构和质量的影响、界面的形成、薄膜生长各阶段的特征等方面的基础研究及各种应用研究上有其特征的优越性。本文采用热丝法在ＳｉＣ昌须增强Ｓｉ３Ｎ４陶瓷、ＡＩＮ陶瓷、Ｓｉ单晶片、Ｍｏ片等基材上沉积出金刚薄膜,并通过ＴＥＭ和ＳＥＭ进行观察,分析和研究了影响金刚石薄膜沉积的因素．     

热丝CVD法沉积金刚石薄膜用灯丝研究现状及改进

热丝化学气相（CVD）法沉积全刚石具有其它沉积方法所无法比拟的优势而受到重视，然而在高温沉积过程中灯丝容易发生形变和挥发所带来的“污染”影响了金刚石沉积膜的质量，本文就热丝法中三种常用灯丝（钨丝、钼丝和铼丝）的高温行为的研究现状进行了综合评述。在此基础上，提出了钽丝表面包钨的新实验，以进一步指导热丝CVD法沉积高质量的金刚石。     

厚钛过渡层缓解铜基上热丝 CVD 金刚石薄膜内应力

以紫铜为基体,在紫铜上先采用磁控溅射技术镀一层金属钛,再以H2和CH4作为反应气体,采用热丝化学气相沉积法(HFCVD)在钛过渡层上合成金刚石薄膜,研究不同钛过渡层厚度对金刚石薄膜质量的影响。利用X射线(XRD)、激光拉曼光谱(Raman)、扫描电镜(SEM)分析薄膜的结构、成分和表面形貌,用能谱仪(EDS)对热处理前后样品的表面进行了元素分析。研究发现,当钛过渡层厚度为3μm时,生成的金刚石薄膜受到较大内应力而发生破裂;当钛过渡层厚度为25μm时,金刚石薄膜质量较好,薄膜受一定内应力,但没有破裂;850℃左右保温热处理12 h,铜原子与钛原子发生了扩散。     

HFCVD金刚石薄膜温度场的数值研究

热丝化学气相沉积（HFCVD）生长金刚石膜过程中，在热丝相关工艺参数取优化值的前提下，对热辐射平衡体系中衬底表面辐照度和衬底温度的空间分布进行了模拟计算，探讨了衬底横向热传导对衬底温度分布的影响。结果表明，在绝热边界和1000K恒温边界条件下，熟传导都使衬底温度的空间分布均匀性明显优于纯热辐射下的温度分布。这些计算结果为大面积高质量金刚石膜的生长进一步提供了理论基础。     

热丝CVD金刚石涂层硬质合金衬底两步法预处理的研究

研究了引入超声振动后酸碱两步法预处理对硬质合金衬底表面去Co催石墨化作用。采用偏压增强辅助热丝化学气相沉积(HFCVD)法,在硬质合金衬底上沉积了一层均匀、光滑的金刚石薄膜。研究结果表明:在酸碱两步法预处理过程中引入超声振动,能够有效的去除硬质合金衬底表面的Co元素,衬底表面发生了明显的粗化;采用Murakami试剂超声振动20 min腐蚀WC相,再用V(H2SO4)∶V(H2O2)=3∶7混合溶液超声振动30 s去除Co相,金刚石薄膜形核密度高、结晶质量好。这说明了超声酸碱两步法预处理能够有效的抑制钴对金刚石薄膜的不利影响,对提高金刚石薄膜与基体之间的附着力起着非常重要的作用。     

大孔径内孔表面金刚石薄膜涂层的制备

应用热丝化学气相沉积（HFCVD）工艺,并采用合适的衬底预处理方法和优化的工艺参数,在大孔径硬质合金内孔表面沉积了金刚石薄膜。分别采用SEM、EDS和喇曼光谱依次对衬底预处理前后内孔表面及沉积的金刚石薄膜进行了表征,并通过压痕实验评估了薄膜的附着强度。该压痕实验结果与薄膜的SEM及喇曼光谱表征的结果具有一致性。结果表明：采用合适的衬底预处理方法和优化的HFCVD工艺,可以在大孔径硬质合金内孔表面沉积高质量的金刚石薄膜。     

甲烷浓度对金刚石薄膜织构的影响

采用热丝化学气相沉积法,以甲烷和氢气为反应气体,在硬质合金YG6基体上沉积了金刚石薄膜。研究了不同的甲烷浓度对金刚石织构变化趋势的影响。分别采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)对金刚石膜的表面形貌、织构形成进行了分析。结果表明:当基体温度为760℃,沉积气压为4×103Pa,甲烷浓度从1%到5%,都形成了(110)织构。但是,当甲烷浓度为3.3%时,有(100)织构。     

CVD金刚石薄膜衬底表面预处理技术进展

评述了化学气相沉积金刚石薄膜衬底表面预处理技术的进展情况。分析了表面研磨法、等离子刻蚀法、浸蚀除钴法、沉积中间层法在衬底表面形成稳定化合物等预处理对CVD金刚石薄沉积的影响。结果表明,金刚石粉末研磨基底、化学浸蚀除钴、在基底表面添加中间层以及在基底表面渗入第三元素并且使这种元素和基底表面的钴形成稳定中间化合物的方法都可提高金刚石的形核率,但大部分研究表明等离子体刻蚀预处理对金刚石的形核则起阻碍作用。     

约束式热丝CVD法制备金刚石的研究

为提高热丝CVD法沉积金刚石薄膜的生长速率,以丙酮和氢气作为反应气源,利用自制的半封闭式空间约束装置,将热丝、衬底、反应气体聚集在狭小空间内,研究不同气体流速条件下的金刚石薄膜沉积情况;使用SEM和Raman光谱表征所合成的薄膜。结果表明:采用约束式沉积法可以显著提高沉积速率,本实验在230 cm3/min（标况）气体流速下获得最大沉积速率6.31 μm/h,比未约束时增大了近一倍。随着气体流速增大,沉积速率先增大后减小;气体流速86~115 cm3/min（标况）时,晶粒尺寸为微米级;气体流速115~575 cm3/min（标况）时,晶粒尺寸减小至纳米级。Raman光谱检测显示:约束式沉积所得薄膜总体质量较好,但随气体流速增大而逐渐降低。      

沉积参数对硬质合金基体微/纳米金刚石薄膜生长的影响

基体温度、反应压力和碳源浓度等沉积参数决定热丝化学气相沉积金刚石薄膜的性能。运用正交试验方法,研究参数对硬质合金基体金刚石薄膜生长的综合作用。采用场发射扫描电镜（FE-SEM）、原子力显微镜（AFM）和拉曼（Raman）光谱检测薄膜的形貌结构、生长速率和成分。结果表明：随着基体温度的降低,金刚石形貌从锥形结构向团簇状结构转变;低反应压力有利于纳米金刚石薄膜的生成;生长速率受反应压力和碳源浓度综合作用的影响。     

不同沉积功率对CVD金刚石涂层性能的影响

利用热丝化学气相沉积法(HFCVD),固定其他工艺参数,通过改变沉积功率在YG6硬质合金上制备金刚石涂层,并利用扫描电镜(SEM)、洛氏硬度计和Raman光谱对涂层进行性能测试。结果表明:两步法处理硬质合金基体,可以有效去除表层的Co,同时增大表面粗糙度,提高金刚石形核率,提高涂层附着力;涂层表面形貌观察可知,沉积功率4kW时,晶形完整,晶粒大小非常均匀致密,晶面主要呈现金刚石典型的(111)面生长;压痕测试表明,当功率为4kW时,涂层的结合力最好,表面均匀、平整;结合Raman光谱分析,功率4kW时,涂层质量很好。     

Time-modulated chemical vapor deposition of diamond films

This article investigates the role of substrate temperature in the deposition of diamond films using a newly developed time-modulated chemical vapor deposition (TMCVD) process. TMCVD was used to deposit polycrystalline diamond coatings onto silicon substrates using hot-filament chemical vapor deposition system. In this investigation, the effect of (a) substrate temperature and (b) methane (CH₄) content in the reactor on diamond film deposition was studied. The distinctive feature of the TMCVD process is that it time-modulates CH₄ flow into the reactor during the complete growth process. It was noted that the substrate temperature fluctuated during the CH₄ modulations, and this significantly affected some key properties of the deposited films. Two sets of samples have been prepared, in each of which there was one sample that was prepared while the substrate temperature fluctuated and the other sample, which was deposited while maintaining the substrate temperature, was fixed. To keep the substrate temperature constant, the filament power was varied accordingly. In this article, the findings are discussed in terms of the CH₄ content in the reactor and the substrate temperature. It was found that secondary nucleation occurred during the high timed CH₄ modulations. The as-deposited films were characterized for morphology, diamond-C phase purity, hardness, and surface roughness using scanning electron microscopy, Raman spectroscopy, Vickers hardness testing, and surface profilometry, respectively.     

Preparation,characterization and electrochemical properties of boron-doped diamond films on Nb substrates

A series of boron-doped polycrystalline diamond films were prepared by hot filament (HF) chemical vapor deposition on Nb substrates. The effects of B/C ratio of reaction gas on film morphology, growth rate, chemical bonding states, phase composition and electrochemical properties of each deposited sample were studied by scanning electron microscopy, Raman spectra, X-ray diffraction, microhardness indentation, and electrochemical analysis. Results show that the average grain size of diamond and the growth rate decrease with increasing the B/C ratio. The diamond films exhibit excellent adhesion under Vickers microhardness testing (9.8 N load). The sample with 2% B/C ratio has a wider potential window and a lower background current as well as a faster redox reaction rate in H₂SO₄solution and KFe(CN)₆ redox system compared with other doping level electrodes.     

氮气对DC-PCVD法制备金刚石薄膜影响的研究

采用直流热阴极等离子体化学气相沉积方法,用甲烷、氢气、氮气的混合气体在Mo基底上成功制备了金刚石薄膜.分别采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、拉曼光谱仪(Raman)对不同流量氮气氛下生长金刚石薄膜的形貌、取向、质量进行了表征.结果表明:适量氮气的加入,不仅可以促进金刚石薄膜的生长速率,还可以促进金刚...     

Effect of deposition temperature on properties of boron-doped diamond films on tungsten carbide substrate

Boron-doped diamond (BDD) films were deposited on the tungsten carbide substrates at different substrate temperatures ranging from 450 to 850 °C by hot filament chemical vapor deposition (HFCVD) method. The effect of deposition temperature on the properties of the boron-doped diamond films on tungsten carbide substrate was investigated. It is found that boron doping obviously enhances the growth rate of diamond films. A relatively high growth rate of 544 nm/h was obtained for the BDD film deposited on the tungsten carbide at 650 °C. The added boron-containing precursor gas apparently reduced activation energy of film growth to be 53.1 kJ/mol, thus accelerated the rate of deposition chemical reaction. Moreover, Raman and XRD analysis showed that heavy boron doping (750 and 850 °C) deteriorated the diamond crystallinity and produced a high defect density in the BDD films. Overall, 600–700 °C is found to be an optimum substrate temperature range for depositing BDD films on tungsten carbide substrate.     

直流等离子体-热丝化学气相沉积金刚石薄膜的研究

通过在传统热丝化学气相沉积装置中引入直流等离子体,设计了直流等离子体-热丝化学气相沉积金刚石薄膜的设备,设备中既包括相互独立的灯丝电压和施加的偏压。通过调节偏压可以控制所形成的等离子体的偏流。在这一改进的系统中研究了金刚石薄膜形核和生长过程,利用扫描电子显微镜（SEM）、X射线衍射（XRD）分析了金刚石的样品,结果表明,施加偏压不仅能大大促进金刚石的形核密度（10^10cm^-2）、提高金刚石薄膜的生长速率,金刚石薄膜的取向也随机取向变为（111）定向生长。     

Influence of intermittently etching on quality of CVD diamond thin films

A new method, called growing-etching repetitional process based on hot filament chemical vapor deposition, was proposed to improve the quality of diamond film. During the deposition carbon source was intermittently closed letting hydrogen etch the surface of the diamond film fi＇om time to time. In order to find whether it is helpful to the films＇ quality, a series of experiments were done. The results show that the new method can enhance the orientation of the chemical vapor deposition diamond films, reduce the graphite phase and increase the film＇s surface resistivity.     

Comparative investigation of smooth polycrystalline diamond films on dental burs by chemical vapor deposition

Depositions of hot filament chemical vapor-deposited diamond on cobalt-cemented tungsten carbide (WC-Co) rotary cutting dental burs are presented. Conventional dental tools made of sintered polycrystalline diamond have a number of problems associated with the heterogeneity of the crystallite, decreased cutting efficiency, and short life. A preferential (111) faceted diamond was obtained after 15 h of deposition at a growth rate of 1.1 μm/h. Diamond-coated WC-Co dental burs and conventional sintered burs are mainly used in turning, milling, and drilling operations for machining metal ceramic hard alloys such as CoCr, composite teeth, and aluminum alloy in the dental laboratory. The influence of structure, the mechanical characteristics of both diamond grains and hard alloys on the wear behavior, as well as the regimen of grinding on diamond wear are considered. Erosion wear properties are also investigated under air-sand erosion testing. After machining with excessive cutting performance, calculations can be made on flank and crater wear areas. Diamond-coated WC-Co dental burs offered significantly better erosion and wear resistance compared with uncoated WC-Co tools and sintered burs. This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in St. Paul, MN.     

Hot-filament chemical vapor deposition of polycrystalline diamond coatings to interlayered steel

Zr-based nitride and carbide coatings have been deposited on high-speed steel by the cathodic arc method. Hot-filament chemical vapor deposition (CVD) has been used to deposit diamond films onto a treated steel surface. The films deposited by CVD were characterized using scanning electron microscopy, x-ray diffraction, and Raman spectroscopy to determine the surface morphology, roughness, crystal structure, and bonding characteristics. This paper was presented at the fourth International Surface Engineering Congress and Exposition held August 1–3, 2005 in St. Paul, MN.