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。     

Effects of pre-treatments and interlayers on the nucleation and growth of diamond coatings on titanium substrates

During diamond deposition on titanium substrates, two processes exist: (1) diffusion of hydrogen into a titanium substrate and the formation of hydride thereby degrading the mechanical properties of the substrate; and (2) competition among the rapid diffusion of carbon atoms into substrates, the formation of carbide and the nucleation of diamond crystals (thereby affecting the nucleation and growth rate of the diamond coating). To increase the diamond nucleation rate and prevent the rapid diffusion of hydrogen and carbon into the substrate, different surface treatments and interlayers were studied in this paper. Results showed that polishing with diamond pastes and ultrasonic pre-treatment in diamond suspensions will significantly increase the nuclei density of diamond crystals. However, the diffusion of hydrogen into the substrate could not be prevented. Pre-etching of the titanium substrate using hydrogen plasma for a short time significantly increased the nuclei density of diamond crystals. Results showed that on a TiN interlayer, there was no significant improvement in diamond nucleation and growth, and the deposited diamond coatings showed poor adhesion. New diamond crystals were formed on the DLC interlayer in which DLC acted as the precursor for diamond nucleation. However, the so-formed diamond coating showed spallation. The plasma nitrided layer could prevent the rapid diffusion of hydrogen and carbon into the titanium substrate, but results showed a relatively low nucleation density of diamond crystals and poor adhesion. A graded interlayer combining plasma nitriding followed by plasma carbonitriding was effective in preventing the rapid diffusion of hydrogen and carbon into the substrate and improving the nucleation rate and adhesion of diamond coating.     

DIAMOND HETEROEPITAXY-NUCLEATION, INTERFACE STRUCTURE, FILM GROWTH

1. IntroductionHeteroepitaxy of textured diamond fiIms has been extensively investigated in recentyears and has led to an improved control of the deposition and to a solid understand-ing of the relationship between deposition parameters and structural al1d physical filmproperties[',2]. In spite of the fact that heteroepitaxy of diamond is hampered in manycases by the large lattice mismatch with the substrate material, for instal1ce fOr some tech-nologically relevant substrates such as Si, mic…     

Cobalt diffusion in different microstructured WC-Co substrates during diamond chemical vapor deposition

Our investigation on diamond deposition using cemented tungsten carbide (WC-Co) has shown that diamond particles deposit at different rates onto micrograin and coarse-grain WC-Co substrates. Diamond deposition was carried out using a parallel-plate plasma-enhanced chemical vapor deposition system, which utilized the bias-enhanced growth (BEG) process. BEG was performed at four different times: 15, 20, 25, and 30 min. The resultant diamond-based deposits were characterized for morphology, microstructure, and crystallinity using scanning electron microscopy. It was found that diamond nucleation initiated at the grain boundaries of the substrates. The present article discusses the possible reasons that can potentially explain our key findings. In particular, the CO diffusion from the bulk material through the grain boundaries and onto the substrate surface using a theoretical approach.     

CVD金属石薄膜及膜——基界面形态

采用直流等离子体射流ＣＶＤ法在硬质合金基体上沉积了多晶金刚石薄膜,借助ＸＲＤ,Ｒａｍａｎ,光谱、ＳＥＭ和ＥＰＭＡ等对金刚石薄膜及膜－基界面的结构、形貌和成分进行了研究,结果表明,结晶度高的刻面型金刚石薄膜质量、纯主较好,膜－基界面处较致密,机械锚固作用明显,结合性能较好,沉积前后基体表面形貌变化很大,存在数十数米厚的脱钴－等离子体刻蚀层,等离子体刻蚀导致脱钴表面更加凹凸不平,为金刚石形核提供了有利     

CVD金刚石薄膜及膜-基界面形态

采用直流等离子体财流CVD法在硬质合金基体上沉积了多晶金刚石薄膜,借助XRD、Raman光谱、SEM和EPMA等对金刚石薄膜及膜-基界面的结构、形貌和成分进行了研究.结果表明,结晶度高的刻面型金刚石薄膜质量、纯度较好,膜-基界面处较致密,机械锚固作用明显,结合性能较好沉积前后基体表面形貌变化很大,存在数十微米厚的脱钴-等离子体刻蚀层,等离子体刻蚀导致脱钻表面更加凹凸不平,为金刚石形核提供了有利条件.     

Hexagonal diamond formation on steel substrates by negative bias microwave plasma enhanced chemical vapor deposition

This paper reports for the first time the synthesis of hexagonal diamond thin films on high-speed steel substrates by multi-mode microwave plasma enhanced chemical vapor deposition. Before deposition of the films, the substrate surface was treated by scratching with diamond powder. The deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy. The XRD patterns of (100) and (101) planes and the Raman peaks at ~ 1317-1322 cm^− 1 were observed, confirming the formation of hexagonal diamond phase in the prepared films. The effects of voltage bias on the phase formation, microstructure and hardness of the films were also studied by setting the voltage to 0, − 70, − 150 and − 190 V. The highest hardness of 23.8 GPa was found in the film having clusters of size about 550 nm deposited under a bias voltage of − 150 V. These clusters were built up of grains of size about 14 nm.     

Characterization of （100）-orientated diamond film grown by HFCVD method with a positive DC bias voltage

The （100）-orientated diamond film was deposited by hot-filament chemical vapor deposition （HFCVD） technology with a positive DC bias voltage. The morphology, X-ray diffraction （XRD）, RMAN spectrum and dark current versus applied voltage characteristics analysis show that the positive dc bias can increase the nucleation density and （100）-orientated growth, making the growth of the high quality diamond film easier and cheaper than using other methods.     

低功率MPCVD制备金刚石薄膜

通过微波等离子体化学气相沉积(MPCVD)法,以CH4/H2为气源,合成高质量金刚石薄膜,在150 W低微波功率下,从衬底预处理方法、沉积气压、流量比等方面对制备高质量金刚石薄膜的工艺参数进行研究.结果表明:高流量比不利于金刚石颗粒的粒径控制,二次形核的存在可以获得近纳米级颗粒尺寸的金刚石薄膜;较大的沉积气压有利于制备...     

微晶/纳米金刚石复合涂层的沉积与表征

采用偏压增强热丝CVD(HFCVD)法,通过引入惰性气体Ar,在经过甲醇新预处理方法处理后的硬质合金衬底表面成功沉积了微晶/纳米金刚石复合涂层。对金刚石复合涂层的表面形貌、成分、表面粗糙度进行了分析和研究。研究结果表明:新的预处理方法能够提高金刚石薄膜与衬底之间的附着强度。Ar的引入使得金刚石薄膜二次形核率更高,颗粒也更加细小,纳米金刚石复合涂层不但具有高的附着强度,而且具有非常低的表面粗糙度。对于拓展纳米金刚石涂层在精密加工领域中的应用具有一定的作用。     

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。     

沉积偏压对AlCrTiN纳米复合涂层力学与抗高温氧化性能的影响

沉积偏压对涂层的结构与性能具有重要影响,为研究其对AlCrTiN纳米复合涂层成分、组织结构、力学与抗高温氧化性能的影响规律,采用磁控溅射技术,改变沉积偏压(-30、-60、-90、-120 V)制备四种AlCrTiN纳米复合涂层。利用X射线衍射仪、扫描电子显微镜、纳米压痕仪等仪器表征涂层的组织结构、成分、力学性能和抗高温氧化性能。研究结果表明：不同偏压下制备的AlCrTiN纳米复合涂层均为NaCl型fcc-(Al,Cr,Ti)N相结构。随着沉积偏压增大,涂层由沿(111)晶面择优生长转变为无明显的择优生长取向,晶粒尺寸降低,残余应力和硬度增大。偏压为-90 V与-120 V时,涂层表面更加致密,具有更高的硬度和弹性模量。在800℃与900℃氧化1 h后,所有涂层表面均生成一层连续致密的Al₂O₃膜。随着沉积偏压增加,氧化膜厚度逐渐降低,表明抗高温氧化性能逐渐增强,这是因为高偏压下涂层组织更致密,且晶粒更细小。研究成果对AlCrTiN纳米复合涂层的综合性能提升与工程化应用具有一定指导意义。     

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。     

Effect of substrate bias voltage on the texture and microstructure of Cu thin films deposited by ion beam deposition

Cu thin films deposited by non-mass separated ion beam deposition under various substrate bias voltages were investigated. The film textures and microstructure were analyzed by X-ray diffraction and field emission scanning electron microscopy, and the resistivity of the film was measured with the Van der Pauw method. It was found that the optimum negative substrate bias voltage for Cu films was −50 V. The Cu films deposited without substrate bias voltage showed a columnar grain structure with small grains and random orientation. However, when a substrate bias voltage of −50 V was applied, the Cu films had a non-columnar structure with a strong (111) texture and large grains. The electrical resistivity of the Cu films decreased remarkably with increasing negative substrate bias voltage, and reaching a minimum value of 1.8±0.13 μΩ cm at the substrate bias voltage of −50V.     

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。     

氩气流量对等离子体喷射法制备的金刚石膜形核的影响

采用100kW级直流电弧等离子喷射法进行金刚石膜沉积,阐述了氩气对维持电弧稳定的重要作用,讨论了氩气流量对衬底表面轰击的影响,氩气流量和不同电弧分区对形核期金刚石表面形貌和晶粒尺寸的影响,以及时间和不同预处理方式对金刚石形核密度的影响。结果表明:随着氩气流量的增加,氩气对衬底表面的轰击作用增强,金刚石膜表面形貌呈现从(111)到(100)的变化规律,金刚石晶粒尺寸减小,晶形变得不完整;弧边位置(100)取向更明显;使用金刚石微粒对衬底进行研磨预处理能显著提高金刚石的形核密度。     

Optical emission spectroscopy as a tool for designing and controlling the deposition of graded TiAlN layers by ECR-assisted reactive RF sputtering

Graded TiAlN layers were deposited by plasma reactive sputtering assisted by electron cyclotron resonance (ECR). For reactive sputtering, dual cathode radio-frequency (RF) magnetron targets, Ti and Al, were used. The deposition process was monitored by optical emission spectroscopy (OES). The OES results indicate that microwave excitation added to RF plasma has contrasting effects on Ti and Al concentration in the gas phase, enhancing titanium and quenching aluminium species reaching the deposited substrate. Thus, by the regulation of the ECR power and the ratio of the nitrogen flow to the nitrogen plus argon flow, the formation of graded layers is allowed. This approach was found to be appropriate for controlling and tailoring the interface between a metallic substrate and a hard coating. The layers were deposited on (100) oriented silicon and M2 steel tools using various combinations of variables, such as power input, bias substrate voltage and gas feed composition. The layers were characterized with regard to structure and composition using X-ray diffractometers and Auger electron spectroscopy. Layers deposited on grounded silicon at a low ECR power (≤100 W) were found to have a (111) oriented crystalline structure; the crystallographic orientation is affected by the bias voltage and substrate composition. Layers deposited at an ECR power >100 W had a random or amorphous structure. The relationship between the OES analyses of the plasma layer and the processing parameters, the structure and the composition of the layers formed are presented and discussed.     

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。     

C60作为石英衬底过渡层气相生长金刚石薄膜

本文采用微波等离子体化学气相沉积方法，以Ｃ６０膜作为过渡层，在石英衬底表面，首次在等离子体预处理中无衬底负偏压条件下的生长出金刚石晶粒。通过扫描电镜观察到金刚石晶粒呈菜花状，生长表现为（１００）晶界。     

圆柱形衬底上高质量金刚石薄膜制备工艺研究

本文以丙酮和氢气为气源，采用优化钽丝排列分布的偏压增强热丝CVD装置对钨丝衬底进行了金刚石薄膜沉积研究。采用扫描电镜(SEM)、拉曼(Raman)光谱等方法检测了金刚石薄膜的质量，分析了沉积工艺对金刚石形核和生长的影响。研究结果分析表明，当直径为1mm的钨丝与热丝之间的最佳距离为4—6mm且反应压力为4665．5Pa、碳源浓度为1．8％时可得到涂层厚度均匀又能覆盖整个钨丝外表面的高质量金刚石薄膜，为以后的自支撑的金刚石薄膜管的制备和回转体刀具的外表面金刚石涂层打下基础。