不同温度渗S处理对TC4表面Mo涂层组织和相形成的影响

利用辉光离子渗的方法,在TC4合金表面首先沉积Mo耐磨涂层,然后对Mo涂层进行450～650℃的渗S处理.研究了温度对Mo涂层渗S表面组织和相形成的影响.结果表明:渗S后Mo涂层表面组织细化,随渗S温度升高,组织致密度增加;650℃渗S后,表面形成相以具有润滑作用的MoS2相为主,另外还有Mo2C硬质相和Ti2S相;450～550℃渗S后,表面形成相以Mo-C化合物为主.     

钛合金表面离子渗钼及耐磨性研究

采用离子渗金属技术对Ti6Al4V(TC4)钛合金进行了离子渗钼,并用扫描电镜、X射线衍射、能谱分析、显微硬度和磨损试验等对渗层的组织、相组成、成分、显微硬度和磨损性能进行了研究。结果表明,TC4合金经离子渗Mo后,表面可形成MoTi相合金层,使材料的硬度有较大的提高,表面常温干摩擦的摩擦因数比基体的低,磨痕比基体的窄,表现出较好的耐磨性能。     

等离子渗Mo的TC11钛合金摩擦磨损性能

在TC11钛合金表面等离子渗Mo以提高其耐磨性。利用SEM、EDS、XRD分析了渗Mo层的微观组织、化学成分及相组成,测定了渗层的硬度分布。采用划痕试验测定了渗层与基体的结合力。通过球盘磨损试验测定了等离子渗Mo层的摩擦磨损性能。结果表明,渗层厚度为30μm;0～10μm表层Mo含量为65%,由表及里呈梯度降低;渗层由单质Mo以及Al8Mo3和Al3Ti等化合物组成,表面硬度达1034 HV0.1;渗层与基体的结合力为70 N;渗层的比磨损率是基体的1/55.4。     

TC4钛合金表面B-Al复合渗层的组织和性能

采用固体粉末包埋渗两步法,在TC4钛合金表面先1050 ℃渗硼 4~6 h再950~1050 ℃渗铝 4 h制备出B-Al复合耐磨渗层。利用X射线衍射仪(XRD)、扫描电镜(SEM)、波谱仪(WDS)和能谱仪(EDS)、显微硬度仪和摩擦磨损试验机对复合渗层的物相组成、显微组织、微区成分、表面硬度和摩擦因数进行测试和分析。结果表明:B-Al复合渗层厚为37~115 μm,主要由TiB₂相和TiAl₃相组成,外层是弥散分布TiB₂的TiAl₃层,向内依次形成厚度较小的TiAl₂、TiAl及Ti₃Al等Ti-Al金属间化合物层。B-Al复合渗层表面硬度为1041.7~1429.4 HV0.1,约为TC4钛合金硬度的3.03~4.16倍;经1050 ℃×6 h渗B后1050 ℃×4 h渗Al,其摩擦因数约为0.3,较TC4钛合金基体下降约25%。     

Nb-Ti-Si 合金表面辉光离子渗 Mo / 包埋渗 Si制备 MoSi2 涂层的研究

目的在Nb-Ti-Si合金表面制备MoSi2涂层。方法先进行辉光离子渗Mo,再进行包埋渗Si。分析温度对渗Mo层表面形貌、厚度、元素互扩散的影响,以及渗Si后涂层的表面形貌和结构。结果在1100℃进行辉光离子渗Mo,渗Mo层与基体形成了显著的互扩散。对渗Mo层进行包埋渗Si后,所形成的涂层组织致密,具有多层结构,由外向内依次为MoSi2层、NbSi2层和Nb5Si3层,在MoSi2和NbSi2层之间存在(Mo,Nb)Si2互扩散区。结论通过辉光离子渗/包埋渗的方法,可以在Nb-Ti-Si合金表面制备Mo Si2涂层,且涂层与基体呈冶金结合,结合较好。     

包渗温度对W6Mo5Cr4V2钢渗硼层组织和性能的影响

采用浆料包渗法,以B4C为供硼剂,NH4Cl+KBF4为复合活化剂,SiC为填充剂,蛋白质(鸡蛋清)为粘结剂,在W6Mo5Cr4V2高速钢表面制备渗硼层。研究了渗硼温度对渗硼层组织和性能的影响。结果表明:包渗温度650℃时,渗硼层组织以Fe2B相为主,在750℃、850℃时,形成了V2B3相,在950℃时渗硼层组织中出现了Fe2Si0.4B0.6相;渗硼层的显微硬度随温度的升高先增后降低,其最小显微硬度值为810 HV,为基体的(235 HV)3.5倍;渗硼层最小摩擦系数为0.12,为基体的1/3。磨损机制在750℃时发生转变,由粘着磨损为主转变为磨料磨损为主。     

钛合金Ti6Al4V表面渗钼层的摩擦磨损性能

利用双层辉光离子渗金属技术在钛合金Ti6Al4V表面进行合金化，形成均匀、致密、厚度为9．4μm的钛钼合金渗层。表面硬度提高3倍左右，达到1050Hκ。采用球盘磨损试验机考察了钛合金Ti6Al4V表面渗钼层和Ti6Al4V钛合金的摩擦性能，得出该合金表面渗Mo后虽然摩擦因数略微增大，但耐磨性提高100余倍；通过对磨损形貌的分析可知，表面渗Mo合金层磨损机制主要表现为粘着及少量微切削。     

消失模铸渗复合层的组织和干滑动磨损性能研究

采用消失模铸渗技术浇注试样,利用扫描电镜及显微硬度仪分析研究了渗层的组织和硬度分布,在MM200磨损试验机上研究了铸渗复合层的磨损性能.研究结果表明:钨、铬碳化物以鱼骨状、菊花状和板条状交织分布在基体中,渗层硬度从表面到内部呈先升后降的趋势,且在距表面渗层2 mm处硬度达到最大值;铸渗复合层的抗磨损能力比普通ZG50提高3～5倍.     

钛合金表面原位合成TiN渗镀层摩擦性能研究

采用双层辉光离子渗金属技术在钛合金TC11表面原位合成TiN渗镀层以提高其耐磨性。利用OM、SEM、EDS、XRD对TiN渗镀层的形貌、组织成分、相结构进行分析;通过显微硬度、划痕试验对TiN层力学性能进行研究;通过常温磨损试验研究了TC11合金表面TiN渗镀层摩擦磨损行为及机理。结果表明,在常温磨损试验条件下TiN层摩擦系数下降一半,表现出较好的减磨耐磨性能;渗镀层显微硬度达到1400HV0.2;渗镀层与基体结合力为45N,结合强度高。     

TC4合金表面TiB2强化TiAl3复合渗层的组织形成及耐磨性能

目的 在TC4钛合金表面制备扩散渗层以提高其耐磨性能.方法 采用包埋渗的方法,首先对TC4合金样品进行950～1100℃下4～8 h渗B,然后再进行950～1100℃下4 h渗Al制备TiB2强化TiAl3复合渗层.通过分析复合渗层的组织结构、表面粗糙度、硬度和磨损率等,结合对包埋渗B和Al过程的热力学分析,阐明TiB2强化TiAl3复合渗层的组织形成机理和耐磨性能.结果 采用包埋渗的方法,可在TC4钛合金表面制备厚度约37～108μm的TiB2强化TiAl3复合渗层,其表面粗糙度约为5.485～9.320μm.复合渗层由硼化物相和Ti-Al金属间化合物相组成,TiAl3层为复合渗层的主体,硼化物主要分布在复合渗层的表层区域,形成TiB2连续层或弥散分布于TiAl3层最外部.通过调整渗Al的温度和时间可调控复合渗层中硼化物的形态和分布.室温干摩擦条件下,TiB2强化TiAl3复合渗层与GCr15对磨时磨损率最低为2.65×10–5 g/(N·m),较相应渗B层可最多降低约75.0％.结论 可采用扩散渗的方法,在TC4钛合金表面实现TiB2强化TiAl3复合渗层的可控制备,复合渗层表现出了比渗B层更优异的耐磨性能.     

Preparation and characterization of jet-electrodeposited nanocrystalline nickel coatings

Nanocrystalline nickel coatings were prepared by both direct current（DC） and pulse current（PC） jet-electrodeposition. The influences of current density and jet velocity on the surface morphology, microstructure and preferred orientation of the coatings obtained were investigated by SEM, TEM and XRD. It is found that the current density strongly affects the microstructure of the nickel coating. An increase of the DC current density results in a slight increase of the grain size and preferred orientation progressive evolution （i.e. from （111） to （200））, whereas an increase of the PC current density leads to a certain decrease of the grain size and preferred orientation change （i.e. from （111） to a strong （220））. Moreover, jet velocity shows no significant effect on the grain size and preferred orientation for the nanocrystalline coatings obtained in both DC and PC within the range of jet velocity studied.     

活性成分对金刚石膜沉积速率和质量的影响

采用微波等离子体化学气相法合成的金刚石膜质量好,但采用常规CH4-H2气体体系,金刚石膜的沉积速率低.为此,实验研究了C2 H5OH-H2、CH4-H2-Ar和CH4-H2-N2等含有活性成分的体系下,微波功率、碳源浓度、气体压力对金刚石膜沉积速率、表面形貌、电阻率的影响.结果表明:使用含氧、氩、氮等活性成分的体系,金...     

Deposition rate and morphology of carbon nanotubes at different positions in a CVD reactor

Carbon nanotubes (CNTs) were synthesized through the catalytic decomposition of a ferrocene-xylene mixture in a horizontal chemical va- por deposition reactor. The deposition rate of CNTs along the axial direction was measured. The morphology of CNTs was observed by scan- ning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the deposition rate of CNTs along the axial direction first increased and later decreased, the position achieving the maximum deposition rate was influenced by the operating conditions. The morphologies of CNTs also changed along the axial direction.     

沉积气氛对电火花沉积Mo2FeB2基金属陶瓷涂层组织与性能的影响

采用电火花沉积分别在空气和氩气中制备了Mo_2FeB_2基金属陶瓷涂层,通过扫描电镜(SEM)、X射线衍射(XRD)、显微硬度计和摩擦磨损试验机研究了沉积气氛对涂层形貌、相组成、硬度和摩擦磨损性能的影响。结果表明,2种气氛中沉积所得涂层的组织结构都致密,涂层与基体间无分层,呈冶金结合的特征,但空气中沉积涂层的表面较粗糙,并发生了严重的氧化,涂层均匀性也较差。它们都主要由非晶相和马氏体相组成,但氩气中沉积的涂层含有更多的非晶相。氩气和空气中沉积涂层的最大显微硬度(HV_(0.05))分别为12 862和10 129 MPa,相差2733 MPa,前者涂层2 h的磨损量几乎仅为后者涂层的1/7,表现出更好的耐磨性。2种涂层的主要磨损机制都是疲劳磨损和磨粒磨损,但氩气中沉积涂层以疲劳磨损为主,空气中沉积涂层则以磨粒磨损为主。     

不同PVD技术沉积TiN涂层的形貌和力学性能研究

本文采用阴极弧沉积、中频磁控溅射及二者的复合技术在GCr15基底上制备了TiN涂层。通过扫描电镜、XRD谱、微米划痕测试、硬度测试以及摩擦磨损测试对涂层的组织结构和力学性能进行了表征及对比。结构表明,采用复合磁控阴极弧技术制备的TiN涂层具有较好的综合性能,如较光滑的表面、较高的结合力和硬度,故磨损率较低。     

Gas phase synthesis of SnOx nanoparticles and characterization

Tin oxide nanoparticles with an average size ranging from 4 to 80 nm were synthesized by oxidation of tin vapor in a low vacuum (10–40 mbar) reactor containing an Ar/O₂ gas mixture. The effect of oxygen and argon partial pressure on the phase formation, size characteristics and morphology of the particles was studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD) method. Electron spectroscopy chemical analysis (ESCA) was used to study the state of the particle surfaces. It was shown that with increasing the oxygen partial pressure, coarser SnO_x particles were synthesized. The ESCA shift for the tin 3d_5/2 line was 2 eV and the separation between this line and the oxygen 1s line was 44 eV. The oxygen 1s line was narrow and symmetric without the OH tail, indicating clean surface. The O/Sn ratios were estimated by using the areas of the tin and oxygen lines, and it was found that the oxidized tin vapor consisted of both SnO and SnO₂. At the oxygen concentration of 50 vol% and the total pressure of 10 mbar, the surface composition was estimated to be SnO_1.2. The particles were transformed to tetragonal SnO₂ after heat treatment at 350 °C for 24 h in air.     

Effects of pressure on metal atom transport and plasma properties during arc ion plating of TiAlN

Arc ion plating is used to deposit titanium and aluminum nitrides as wear and corrosion resistant layers on the surface of steel tools. In this study, the deposition efficiency for the evaporated metal atoms in arc ion plating was obtained by a view factor solution for the collisionless transport and a diffusion solution for the continuum transport. In the diffusion solution, the deposition efficiency decreases rapidly with pressure. A global nitrogen plasma model with a set of simplified plasma chemistry was used to investigate the plasma properties at pressures ranging from several mTorr up to 50 mTorr. The results indicate that the electron temperature, the ratio of electric field to gas density, and the nitrogen atom density all decrease with increasing pressure, while the plasma density increases. Based on the combined considerations of deposition efficiency and effective ion bombardment of the films on the substrate, an operating pressure range from 20 to 30 mTorr is recommended for highly efficient (Ti, Al)N coating during film deposition.     

置换法化学沉积银的动力学研究

试验了影响置换化学法在铜基材上沉积金属银过程和速度的主要因素,分析诸因素对过程动力学的作用,从而建立了镀液沉积速度的经验方程.验证的结果表明,这一经验方程式对化学沉积银过程的调节和产物的控制具有一定的参考.     

金属零件熔积成形过程形状质量的可视化诊断

利用单目视觉技术进行熔积成形过程监测;借助数字图像处理技术对熔积层形貌信息进行处理获得熔积层的宽度信息;以图像处理获得的熔积层缺陷点像素坐标为源头,通过文中建立的空间定位数学模型还原其三维空间位置信息,最后进行熔积层检测试验.结果表明,文中提出的单目视觉定位数学模型和数字图像处理算法能够准确的对熔积层宽度进行非接触地实时监测,并能够对可能出现的缺陷点进行快速的识别与准确的定位.因此文中方法能够实时调整与优化快速成形过程中的熔积工艺参数,保证制件形状与尺寸精度.     

Characterization of calcium titanate thin films deposited on titanium with reactive sputtering and pulsed laser depositions

In the present study, characteristics of calcium titanate thin films deposited on titanium by reactive sputtering and pulsed laser deposition techniques were investigated. In both techniques, a calcium titanate target was used as a deposition source, and the titanium substrate was heated at 873 K during the deposition. The oxygen flow for the reactive sputtering was in the range of 1 to 10 sccm, and the oxygen pressure for the pulsed laser deposition was in the range of 0.13 to 13 Pa. The deposited films were crystallized into perovskite-type calcium titanate; furthermore, a titanium-dioxide layer formed in the interface between the film and substrate. In the film deposited by reactive sputtering with low oxygen flow, titanium-to-calcium ratio ([Ti]/[Ca]) is lower than that of stoichiometric calcium titanate due to the formation of calcium hydroxide. The ratio increases with an increase of oxygen flow, and the ratio of the film deposited with a 10-sccm oxygen flow was almost in accordance with that of stoichiometric calcium titanate. On the other hand, in the pulsed laser deposition, [Ti]/[Ca] ratios of the deposited film were almost in accordance with that of stoichiometric calcium titanate at the oxygen pressure under the present experimental condition. In both deposition techniques, the thickness of the titanium-oxide layer increased with an increase of the amount of oxygen gases. The results indicate that the pulsed laser deposition has an advantage for the preparation of the stoichiometric calcium titanate film without formation of a thick titanium-oxide layer.