沉积温度对硬质合金基体表面硼掺杂金刚石涂层性能的影响（英文）

采用热丝化学气相沉积法在硬质合金基体表面沉积一层硼掺杂金刚石(BDD)薄膜,沉积温度为450~850℃。研究沉积温度对硬质合金基体表面硼掺杂金刚石涂层性能的影响。研究结果表明,硼掺杂明显有助于提高金刚石涂层的生长速率。当沉积温度为650℃时,BDD薄膜在硬质合金基体表面的生长速率可达到544 nm/h。这可能是由于反应气体的硼原子降低了薄膜生长的激活能(53.1 k J/mol),从而加快了沉积化学反应速度。此外,拉曼光谱和X射线衍射结果显示,高浓度硼掺杂(750和850℃)会破坏金刚石的晶格结构,从而使薄膜内缺陷增加。综上,硬质合金基体表面BDD薄膜的优选沉积温度范围为600~700℃。     

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。     

沉积参数对Mo-Re合金基体上沉积金刚石薄膜的影响

采用热丝化学气相沉积法(HFCVD),以甲烷和氢气为反应气体,在综合性能良好的Mo-40%Re(摩尔分数)合金基体上沉积金刚石薄膜.采用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)和显微激光拉曼光谱仪(Raman)分别对金刚石薄膜相组成、表面形貌、晶粒大小和质量等进行检测分析,研究CVD沉积参数,如基体温度(θs)、碳源浓度(R,Cn4的体积分数)和沉积压强(p),对金刚石形核、生长和金刚石成膜的影响.结果表明在合适的基体预处理条件下,当θs=750℃,R=-3%,p=3.5kPa时,薄膜平均线生长速率高达1μm/h,得到的金刚石膜完整致密,晶粒大小均匀,纯度较高,具有明显的(111)织构.     

多晶氧化铍陶瓷上金刚石薄膜的生长

采用热丝化学气相沉积(HFCVD)系统,以CH4和H2为反应气体,在多晶氧化铍陶瓷基体上沉积了金刚石薄膜.采用场发射扫描电子显微镜(FESEM)、原子力显微镜(AFM)和激光热物性测试仪进行检测分析,研究工艺参数对金刚石薄膜生长及膜/基复合体热学性能的影响.结果表明:随着CH4浓度的增加(或CH4浓度一定,反应气体总流量增加),金刚石晶粒尺寸逐渐减小,膜/基复合体的热导率逐渐降低;当CH4浓度为2%(体积分数),流量为30 cm3/min,压强为1.33 kPa时,沉积的膜/基复合体的热导率最高,可达2.663 W/(cm·K).     

HFCVD在硬质合金基体上沉积（110）＆（100）金刚石薄膜

以CH4和H2为反应气体,用热丝化学气相沉积(HFCVD)法在YG6(WC-6%Co)硬质合金基体上沉积了具有(110)和(100)织构的金刚石薄膜.用扫描电子显微镜、X射线衍射仪、压痕仪对样品进行了分析.结果表明金刚石薄膜由约1μm大小立方金刚石晶粒组成,其形核密度大于2×108/m2;(110)和(100)织构系数分别为0.59和0.033,压痕荷载为588N时附着性能良好.     

YG13硼化处理后沉积气压对金刚石薄膜的影响

采用超高真空热丝化学气相沉积（HFCVD）系统,以甲烷和氢气为反应气体,在YG13（WC-13%Co）硬质合金基体上沉积金刚石薄膜。用场发射扫描电子显微镜（FESEM）和X射线衍射仪（XRD）对金刚石薄膜进行检测分析,研究YG13经950℃、3h硼化预处理后沉积气压对金刚石薄膜形貌和生长织构的影响;通过压痕法比较硼化与二步法两种预处理方法对金刚石薄膜附着性能的影响。结果表明,基体经硼化预处理后表面形成CoB、CoW2B2、CoW3B3相;当沉积温度为750～800℃,碳源浓度为3.3%时,薄膜表面形貌和生长织构随着沉积气压改变有明显的变化;硼化预处理后所得样品在1500N载荷下压痕表现出良好的附着性能,较二步法预处理更加有效地改善了膜-基附着性能。     

YG6硼化综合处理后基体温度对金刚石薄膜的影响

采用热丝化学气相沉积(HFCVD)方法,以甲烷和氢气为反应气体,在经950℃×6h硼化综合处理后的YG6(WC–6%Co)硬质合金基体上制备了金刚石膜。使用场发射扫描电子显微镜(FESEM)和X射线衍射仪(XRD)对金刚石薄膜进行检测分析、对比,研究了基体温度对金刚石薄膜形貌和生长织构的影响,比较了硼化综合处理与二步法处理对金刚石薄膜附着性能的影响。结果表明,当沉积气压为2.67kPa,碳源浓度为3.3%时,薄膜表面形貌和生长织构随着基体温度改变有明显的变化,硼化综合处理较二步法预处理更加有效地改善了膜–基附着性能。     

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。     

SiC基底HFCVD金刚石薄膜摩擦磨损性能

利用热丝化学气相沉积技术在碳化硅基底上制备微米金刚石薄膜、纳米金刚石薄膜和金刚石–石墨复合薄膜,采用扫描电子显微镜、原子力显微镜和拉曼光谱仪对不同金刚石薄膜的表面形貌和微观结构进行表征,通过摩擦磨损实验测试金刚石薄膜的摩擦系数并计算其磨损率,对比研究不同种类金刚石薄膜的摩擦磨损性能。结果表明：金刚石–石墨复合薄膜具有较好的摩擦磨损性能,薄膜表面粗糙度为53.8 nm,摩擦系数为0.040,和纳米金刚石薄膜(0.037)相当;金刚石–石墨复合薄膜的磨损率最低,为2.07×10^-7 mm³·N^-1·m^-1。在相同实验条件下,同碳化硅基底的磨损率(9.89×10^-5 mm³·N^-1·m^-1)和摩擦系数(0.580)相比,所有金刚石薄膜的磨损率和摩擦系数均有明显提升,说明在SiC基体表面沉积金刚石薄膜能够显著提高碳化硅材料在摩擦学领域的使役性能。     

球形金刚石的形成机制

在 p Si(10 0 )基体上用热丝CVD法沉积了球形金刚石薄膜。用XL30FEG扫描电镜、X射线衍射仪及Raman光谱仪对不同沉积时间的球形金刚石的微观形貌及组成成分进行了研究 ,并对其形成机制进行了分析。结果表明 :球形金刚石的颗粒密度和形核密度一致 ,球形金刚石由微晶金刚石组成 ,晶粒尺寸为 70～ 2 0 0nm ;微晶金刚石是沉积过程中快速二次形核而形成 ,呈无序分布 ;球形金刚石薄膜以二次形核方式繁衍生长     

Influence of Chloride and PEG on Electrochemical Nucleation of Copper

The influence of chloride ions and polyethylene glycol (PEG) on the nucleation of copper on glassy carbon from acid sulphate solutions was studied by measuring potentiostatic current transients (the chronoamperometry method). It was found that instantaneous nucleation occurred at the surface for solutions without additives. The initial stage of copper nucleation did not change on addition of chloride ions, but gradually changed from progressive nucleation to instantaneous nucleation at increasing potentials in the presence of PEG. Chloride ions and PEG increase the nucleation rate and the nuclear number density of nuclei at the surface.     

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。     

Laser-ablated carbon plasmas: emission spectroscopy and thin film growth

The effect of the ambient gas pressure on thin films of carbon deposited by laser ablation using third harmonics at 355 nm of an Nd: YAG laser is reported. Scanning electron microscopy, X-ray diffraction and Raman spectroscopy have been used to characterize the deposited films. The nucleation density and morphology of the films and microcrystals are strongly affected by the pressure of the ambient gas. It is found that there is an optimum pressure at which nucleation is more pronounced. The optical emission spectra of C₂, recorded as a function of the laser energy and background gas pressures, is used to estimate the vibrational temperature of the species. The vibrational temperature of the molecular C₂ species is estimated using Swan bands. The intensity of the Swan bands increased as the pressure of the background gas (argon) was increased. The vibrational temperature depends on the laser energy, and on the choice of the ambient gas and its pressure. The correlation of the vibrational temperature with characteristics of the deposited film and with plasma plume parameters is discussed.     

单晶金属衬底上多层石墨烯的可控生长进展

石墨烯作为一种理想的二维材料,具有机械性能好、电阻率低、热导率高等优点,受到人们的广泛关注。特别地,通过调控石墨烯层数可以改变石墨烯的电学性质,如带隙可调、半导体性质、特殊量子行为等,拓展石墨烯在柔性透明电极、高温超导、高性能传感等领域的应用。目前,人们已对金属衬底上高质量单层石墨烯的制备做了很多研究,发现当单层石墨烯覆盖金属衬底时,衬底将失去催化活性,使得高质量多层石墨烯的可控生长变得非常困难。为了制备多层石墨烯,研究人员已经探索了多种生长方法。总结了单晶金属衬底上多层石墨烯两种常见的生长模式,即表面成核控制的层层往上生长和偏析成核控制的层层往下生长,表面成核控制生长包括气源分子束外延、等离子体化学气相沉积等,偏析成核控制生长包括合金衬底偏析、单质金属衬底偏析等。针对多层石墨烯的各种生长方法,分别从成核密度、晶畴尺寸、层厚均匀性等方面进行了分析总结。最后,对该领域的发展趋势进行了展望,有助于为多层石墨烯的可控生长提供新的解决方案,促进多层石墨烯的发展与应用。     

Effect of n-Al2O3 on electrochemical nucleation and chemical binding interaction in nickel electrodeposition

The electrochemical nucleation mechanism of nickel on the vitreous carbon electrode from n-Al2 Os/Ni composite brush plating system was investigated using potential step method. The interaction between nano-alumina and matrix metal was researched by X-ray photoelectron spectrometry. The results show that the nano-alumina leads to the increasing of the nuclei density, nucleation rate constant and crystal growth rate during nickel electrocrystallization. Nano-alumina is found to be beneficial for nucleation and growth of nickel. During the electrodeposition process, some nanoparticles are captured effectively on the growing metal surface. As the absorbed nickel atoms are diffusing on electrode surface, some of them arrive at the interface between the captured nano-alumina and the growing metal surface. The unsaturated bond of oxygen on nano-alumina surface can capture some of the absorbed nickel atoms and form nickel-oxygen chemical bond. The new nucleation and growth sites of nickel atoms appear at the interfaces between nanoparticles and metal growing surface. Nanoparticles are embedded gradually in the newly deposited nickel atoms, which leads to the formation of the composite coating. The results indicate that the nano-alumina takes part in the electrode reaction and the unsaturated chemical bond of oxygen on nanoparticle surface can combine with the absorbed nickel atoms by way of chemical bond.     

Effect of π-Al_2O_3 on electrochemical nucleation and chemical binding interaction in nickel electrodeposition

1 INTRODUCTION In recent years , nanometer composite electric brush plating technology has been developed.It is a kind of novel surface repairingtechnology ,which can prepare excellent surface coating[1 7]. The technology is at the stage of development , its foundational theory and application field must be expended. Up to now, investigations have been mainly focused on preparing coating,testing per- formance and developing new brush-plating solu- tion,little attentionis paidto the study …     

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。     

Nucleation and growth of combustion flame deposited diamond on silicon nitride

The effect of substrate temperature (T_s) on the nucleation and growth of diamond on silicon nitride (Si₃N₄) based substrates deposited via the oxy-acetylene combustion flame technique was investigated. The diamond deposits were characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The nucleation density of the resulting deposits, which was of the order 10⁵ nuclei/cm², was used to approximate the activation energy for heterogeneous nucleation of diamond as32 – 40 kcal/mol. An Arrhenius plot of particle growth rate was used to calculate the activation energy for diamond growth as9.4 and 8.3 kcal/mol in the center and outside annulus of the deposit, respectively. These results suggest that the heterogeneous nucleation of diamond is a highly energetic process and may in fact be responsible for the observed low nucleation density of diamond on Si₃N₄. Thermodynamic analysis of gas/substrate reactions under conventional process conditions predicted that SiC formation, which is known to be a necessary precursor to diamond nucleation on Si, is energetically forbidden. Via kinetic and thermodynamic considerations, a patented in situ multistage deposition technique was developed which yielded continuous diamond coatings on Si₃N₄ substrates without extensive substrate preparation.     

基底表面状态对异质形核影响的实验研究

对铸型型壁形核点密度的研究,在铸造领域有着重要意义.从润湿性角度出发,通过水在基底上的润湿角来计算基底的表面能,并引入具有标度不变性的分形雏数以定量表征粗糙表面粗糙程度,研究形核基底表面状态对NH4Cl晶粒异质形核行为的影响规律.结果表明,表面能和微观形貌对基底表面的润湿性和形核特性具有显著影响.刻蚀获得的LY12基底...     

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.