TC4钛合金表面镀Cu摩擦磨损性能的研究

采用一种反应熔敷法,在钽合金表面制备一层较厚的碳化物强化层,进行钽合金的表面强化.以TaW12合金板材作为基板,将Ta粉和C粉混合,均匀涂覆在TaW12合金板材表面.以电弧为熔敷热源,在整个粉末涂覆面上进行逐行扫描,引发混合粉末与基板的反应熔融和固相扩散,获得表面硬化层.表面熔敷层完全致密,为熔融结晶状态.外表面呈周期性的波浪形,无裂纹,无气孔显现.熔敷层主要是Ta2C相与钽固溶体混合的共晶凝固组织,等轴状和条状的Ta2C相分布在Ta合金基体上,呈现一定的方向性,大多数近似垂直于板面.熔敷层与基体之间有一层由固态扩散产生的组织,大量针状Ta2C相在基体上交叉析出,形成网状结构.Ta2C相尺寸由外向内变小,逐步成为细小点状析出.熔敷层与过渡层间为固液界面,结合非常好,无裂纹和空洞存在.表面熔敷层平均维氏硬度为6690 MPa,达到了基体材料硬度的3倍.过渡层中硬度急剧下降,为熔敷层的一半.     

基于水下电场测量的Ag/AgCl多孔电极性能研究

以金属钽板为阳极,不锈钢板为阴极,以四丁基溴化铵为导电剂,在二乙胺体系中直接电化学合成5-二乙基胺钽(Ta[N(C2H5)2]5).采用红外光谱(FT-IR)、核磁共振(NMR)、差热分析(TG-DTG.)及等离子质谱(ICP-Mass)对5 kPa 压力下减压蒸馏分离得到Ta[N(C2H5)2]5产品进行了分析检测.分析结果表明得到的产品确实是纯度99.997％的有机胺钽化合物Ta[N(C2H5)2]5.钽阳极溶解机理研究表明,钽阳极在电流的作用下发生点腐蚀,钽阳极在电流及四丁溴化铵的作用下首先生成Ta(NH10C4)n(Br)m,之后Ta(NH10C4)n(Br)m不断被传输到阴极后继续与二乙胺反应,逐步脱去溴离子Br,并最终生成有机胺钽盐Ta[N(C2H5)2]5.     

沉积温度对渗钽层组织与耐蚀性能的影响

<正> 钽是一个负电性强的金属,其平衡电位相当低(E_(Ta/Ta_2O_3)=-0.81V),无论是在氧化性的还是在还原性的含氯化物的酸中(即使氧含量很小)都能生成致密的氧化膜(Ta_2O_5),这种膜的粘着性能好,牢固且稳定,在低于260℃的温度下有很好的保护性。由于钽的提炼和加工困难,价格昂贵。因此,研究和开发渗钽技术有它重要的实际意义。     

网状阴极法在碳钢表面沉积氮化钽薄膜的研究

介绍了一种在钢铁基体上制备氮化钽薄膜的新方法———网状阴极法。其设备简单、价格低廉。实验中发现 ,在工艺参数调配合适的条件下 ,可制备出结构为面心立方和密排六方结构的氮化钽薄膜。薄膜较致密且均匀 ,与基体结合良好。分析了优选工艺参数条件下合成的氮化钽膜的成分、组织、表面和断口形貌及结合力。     

等离子体对钽表面渗氮处理的影响

采用SEM,XRD等手段对钽在氢与氮等离子体中形成的表面层进行了分析,试验表明,在外界参数相同的情况下,H N等离子体的存在改变了Ta表面在H-O-N气氛中的反应路径,使反应产物由无等离子体时的Ta2O5变成了Ta6N2.57,因此处理后的表面粗糙度比无等离子体时下降了一个数量级;对等离子体的作用机理进行了探讨,认为是等离子体的存在改变了介质成分和Ta表面附近的“阴极鞘层”与Ta表面相互作用抑制了粗糙的Ta2O5形成。     

Korrosionsbeständige chemische Apparaturen aus explosionsplattiertem Tantal

Explosion-clad sheet metal for corrosion resistant chemical equipment Explosion cladding operates without external heat input and does not require haftintermediate bonding layers. The process Prakis practically independent from the base metal. As a consequence, the tantalum layer obtained is extremely pure and of geuniform thickness. The compound material is characterized by high shear and flexural strengths. These experimental experiences have been used in designing an autoclave (120 litres) of carbon steel with Ta cladding. The design required the development of a new welding technoloy, in order to prevent Ta becoming contaminated by iron pickup. According to this method the steel is welded first, after having been reinforced by Ta inserts below the tantulum layer; this me thod facilitates the subsequent welding of the tantalum side. The welding method is used for repair purposes, too. Similar autoclaves having capacities up to 6000 litres are in the design stage.     

Electrochemical behavior of tantalum in ethylene carbonate and aluminum chloride solvate ionic liquid

To investigate the electrochemical reduction mechanism of Ta(V) in ethylene carbonate and aluminum chloride (EC−AlCl₃) solvate ionic liquid, cyclic voltammetry experiments were conducted on a tungsten working electrode. Four reduction peaks were observed in the cyclic voltammogram of the EC−AlCl₃−TaCl₅ ionic liquid. The reduction peaks at −0.55, −0.72, and −1.12 V (vs Al) were related to the reduction of Ta(V) to tantalum metal by three stages including the formation of Ta(IV) and Ta(III) complex ions. The reduction of Ta(III) to tantalum metal was an irreversible diffusion-controlled reaction with a diffusion coefficient of 3.7×10⁻⁷ cm²/s at 323 K, and the diffusion activation energy was 77 kJ/mol. Moreover, the cathode products at 323 K were characterized by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The results showed that tantalum metal and tantalum oxides were obtained by potentiostatic electrodeposition at −0.8 V for 2 h.     

强束流钽、碳离子双注入H13钢的研究

选用强碳化物形成元素钽作为金属蒸汽真空弧离子源(metal vapor vacuum arc，简称MEWA)的阴极，对H13钢进行了钽离子注入表面改性研究。对比了Ta、C离子单注入和Ta、C离子双注入的效果，测量了离子注入表面的成分，考察了注入表面的相结构。在相同的摩擦磨损试验条件下，测量了摩擦因数和磨损量，研究表明，和未注入Ta、C单离子注入相比，Ta、C离子双注入提高了H13钢的耐磨性并大幅度降低了其表面的摩擦因数。双注入区出现的弥散TaC相是耐磨性提高、摩擦因数降低的主要原因。在试验条件下，对H13钢单注入Ta时未发现TaC的形成。     

Effect of carbon on the sulphidation of cobalt-tantalum alloys

The sulphidation of cobalt-tantalum-carbon alloys containing 10 and 15 wt% Ta and carbon in the range 0–1 wt%, was carried out in H₂-H₂S mixture containing 10% by volume H₂S. The reaction kinetics at 800–1000°C were followed thermo-gravimetrically and the scale products examined in detail using metallographic and X-ray diffraction techniques. In these sulphidation conditions (10% H₂S – 90% H₂) addition of 10 and 15% Ta to cobalt was unable to suppress the formation of liquid cobalt-rich sulphides; consequently, very rapid rates of alloy consumption were attained. Decreasing the temperature resulted in the distribution of the tantalum sulphides in a fine scale. Transport of cobalt through the inner layer was sufficiently rapid to form an outer, molten sulphide layer. The inability of tantalum-rich sulphides to develop into a continuous layer appears to be responsible for the disappointing effect of tantalum on the sulphidation resistance. Increasing carbon contents in the alloy increase the sulphidation rate, but the increase is not very dramatic.     

CVD温度对钽沉积层性能的影响

介绍了化学气相沉积(CVD)制备难熔金属钽涂层的原理及方法。采用冷壁式化学气相沉积法,在钼基体上沉积出难熔金属钽层。分析研究了CVD温度对沉积层的沉积速率、组织、结构和硬度等的影响。结果表明:在1000～1200℃温度范围,沉积速率随温度升高而增大;当温度超过1200℃时,沉积速率随温度的升高反而略有减小;沉积层组织呈柱状晶并随温度的升高逐渐增大;沉积层的硬度及密度随温度的升高而逐渐降低。化学气相沉积钽的最佳温度在1100℃左右。     

The Oxidation of cobalt-tantalum base alloys containing carbon

The oxidation of cobalt-tantalum carbon alloys, containing 10 and 15 wt.% Ta and carbon in the range 0–1 wt%, was carried out in oxygen and air at atmospheric pressure at 900, 1000 and 1100°C. The alloys oxidised according to the parabolic rate law with activation energy of about 38 Kcal/mole. In general, the addition of tantalum decreases the oxidation rates, in comparison with cobalt and with the same mass of chromium added to cobalt. Again, the presence of carbon in the Co-Ta alloys decreases its oxidation rates in comparison with carbon-free alloys. The scales formed on Co-Ta and Co-Ta-C alloys consist mainly of an outer layer of cobalt oxide, CoO, and an inner porous layer of mixture of oxides: cobalt oxide; CoO, tantalum oxide; Ta₂O₅, and solid solution of these two oxides; CoTaO₄ at all temperatures in the range of 900°-1100°C. The binary Co ?10% Ta and Co ?15% Ta show an internal oxidation along the internal phase, increasing of alloy tantalum content increases the density of the internal phase. The presence of carbon in the ternary Co-Ta-C alloys has little effect and there is no apparent preferential penetration along the tantalum carbide network. In contrast to carbide present in Co-Cr-C alloys, where these carbides were preferentially attacked, the outer scale was disrupted, due to the formation of carbon gaseous oxides.     

Copper diffusion into silicon substrates through TaN and Ta/TaN multilayer barriers

A study of copper (Cu) diffusion into silicon substrates through Ta nitride (TaN) and tantalum (Ta/TaN) layers was investigated based on an experimental approach. TaN _x and Ta/TaN _x thin films were deposited by radiofrequency sputtering under argon (Ar) and Ar-nitrogen (N) plasma. The influence of the N₂ partial pressure on the microstructure and the electrical properties is reported. X-ray diffraction patterns showed that the increase of the N₂ partial pressure, from 2 to 10.7%, induces a change in the composition of the δTaN phase, from TaN to TaN_1.13, as well as an evolution of the dominant crystallographic orientation. This composition change is related to a drastic increase of the electrical resistivity over a N₂ partial pressure of 7.3%. The efficiency of TaN layers and Ta/TaN multilayer diffusion barriers was investigated after annealing at temperatures between 600 and 900 °C in vacuum. Secondary ion mass spectrometry profiles showed that Cu diffuses from the surface layer through the TaN barrier from 600 °C. Cu diffusion mechanisms are modified in the presence of a Ta sublayer. This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized by Yongho Sohn of the University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University.     

THE IMPROVEMENT IN FRICTION AND WEAR RESISTANCE FOR Ta and Ta+C IMPLANTED Cr12 STEEL

1.IntroductionDuringthepasttwodecadestherehasbeensignificalltprogressinthefieldofsurfacetreatmentforreducingwearincoolextrusiondiesteel.Metalionimplantationhasseveraldistinctadvantagesoverothertechniquesforthesurfacemodificationofmaterials.FOrmodifyingwearresistancesofmetals,thesignificanteffectsusuallyinvolvehighdoseionimplantation.Themajorlimitationofimplantationwithmetallicionshasbeenthelongprocessingtimeduetosmallbeamcurrefltofconventionalimplanters.Metalvaporvacuumarc(MEVVA)ionsourceca…     

生物活性多孔钽支架的构建及其初步生物学评价

表面生物活性涂层构建是提升金属内植物骨整合能力的有效途径,本研究利用电化学沉积技术在多孔钽支架表面构建生物活性羟基磷灰石(HA)涂层。通过接触角和比表面积测试发现,HA涂层的构建显著提升了多孔钽表面亲水性,并增加了其比表面积。利用模拟体液浸泡试验评估支架生物活性,发现仅浸泡3天后,多孔钽支架表面就已被类骨磷灰石沉积所覆盖。建成骨细胞培养模型,通过激光共聚焦观察及细胞增殖测试发现,所有支架均具有良好的细胞相容性。并且,细胞共培养5天后,HA涂层化多孔钽支架表面细胞的增殖率分别是未改性材料组和空白对照组的1.1和1.4倍,呈现了更大的促细胞增殖潜力。本研究中所制备的生物活性多孔钽支架具备快速诱导类骨磷灰石沉积能力,能够促进成骨细胞在其表面的贴附和增殖,在骨修复领域具有较大的临床应用前景。     

Roles of temperature and humidity in the oxidation of sputter-deposited Cu-Ta alloys in air

Oxidation behavior of a series of Cu-Ta alloys prepared by co-deposition of RF sputtered pure copper and tantalum was studied in air. Alloy composition, oxidation temperature and relative humidity (RH) ranges examined were 5-69 at.% Ta (alloys with 22-69 at.% Ta were amorphous), 40-85°C and 20-70%, respectively. Although Cu-58at.%Ta alloy showed no apparent change, some of the alloys exposed to an air at 70°C and RH=70% for 60 h showed change in color. The Cu-5at.%Ta alloy showed bright blue, and alloys with 10-30 at.% Ta were all turned to reddish color by oxidation. Among the alloys examined, Cu-24at.%Ta alloy showed the highest oxidation rate under the above condition. The in-depth profiles of Cu-24at.%Ta alloy specimens oxidized for 6-60 h in the air of 70°C and RH=70% indicated existence of metallic Cu-layer on the top of Ta-rich oxide layer and Cu-enriched alloy layer under the oxide film. The metallic copper layer must be caused by diffusion of metallic copper from the Cu-enriched alloy layer to the top of the surface similarly to the oxidation of Cu-Zr alloys at room temperature in a laboratory air. Even Cu-Ta alloys which show very high corrosion resistance in HCl solutions does not always have high corrosion resistance to oxidation in air because of difference in surface film formation process and the resulting compositions and film structure.     

Tantalum oxide barrier in magnetic tunnel junctions

Tantalum as an insulating barrier can take the place of Al in magnetic tunnel junctions (MTJs). Ta barriers in MTJs were fabricated by natural oxidation. X-ray photoelectron spectroscopy (XPS) was used to characterize the oxidation states of Ta barrier. The experimental results show that the chemical state of tantalum is pure Ta~(5+) and the thickness of the oxide is 1.3 nm. The unoxidized Ta in the barrier may chemically reacted with NiFe layer which is usually used in MTJs to form an intermetallic compound, NiTa_2. A magnetic "dead layer" could be produced in the NiFe/Ta interface. The "dead layer" is likely to influence the spinning electron transport and the magnetoresistance effect.     

Ta1/0Cr18Ni9薄板储能焊熔核高熵化机理

针对钽与钢之间物化性质差异大，焊接时易产生脆性金属间化合物而导致熔焊接头性能低下及裂纹等问题，按照熔核金属高熵化技术思路，利用基于密度泛函理论的热力学第一性原理设计出新型中间层合金Ta₂₀Fe₂₀Ni₂₀Cr₂₀Co₂₀，结合熔合比得到适用于钽/钢储能焊中间层合金成分为Ta₇Ni₃₂Cr₁₉Co₄₂. 采用真空电弧炉熔制纽扣合金锭，继而使用单辊急冷法制备出中间合金箔材，将其用于Ta1/0Cr18Ni9薄板的储能焊连接. 结果表明，在储能焊条件下，Ta1/Ta₇Ni₃₂Cr₁₉Co₄₂/0Cr18Ni9搭接接头形成形貌规则、完整，长径约0.8 mm的扁球形熔核，熔核整体向钢侧发生了偏移. 熔核组织由简单的FCC固溶体组成，无金属间化合物析出，具有典型的高熵合金特征，实现了熔核金属高熵化. 在焊接电压1 000 V，电容500 μF，电极压力30 N下，Ta1/Ta₇Ni₃₂Cr₁₉Co₄₂/0Cr18Ni9储能焊接头平均强度可达到395 MPa.     

The effect of phosphorus addition on the corrosion behavior of ARC-MELTED Ni10TaP alloys in 12 M HCl

The corrosion resistance of arc-melted Ni10TaP alloys containing 0, 10 and 20 at% phosphorus in 12 M HCl solution at 30 °C was investigated. The alloys containing 0 and 10 at% phosphorus suffer severe corrosion. The addition of 20 at% phosphorus to crystalline Ni10Ta alloy results in a three-orders-of-magnitude decrease in the corrosion rate. The open circuit potentials of the Ni10Ta alloys containing 0 and 10 at% phosphorus stay almost constant in the active region of nickel, while the open circuit potential of the Ni10Ta20P alloy increases almost linearly in the initial 2 h. The Ni10Ta alloy consists of intermetallic Ni₈Ta and immersion in 12 M HCl results in faceting dissolution. Ni10Ta10P alloy is composed of major Ni₈Ta and Ni₃P phases and minor Ni₂Ta and Ni₂P phases. Immersion of Ni10Ta10P alloy leads to preferential dissolution of the Ni₈Ta phase and to continuous thickening of the corrosion product film consisting mostly of tantalum as cations. Ni 10Ta20P alloy consists of Ni₂Ta, Ni₃P, Ni₂P and NiP phases. Immersion of Ni10Ta20P alloy gives rise to initial increase in elemental phosphorus on the surface as a result of selective dissolution of nickel and selective oxidation of tantalum. The formation of elemental phosphorus with a high cathodic activity is responsible for the initial ennoblement of the open circuit potential and for the formation of the passive film in which tantalum is highly concentrated. The higher corrosion resistance of Ni10Ta20P alloy than Ni10Ta10P alloy is attributable to the formation of the Ni₂Ta phase with a higher tantalum content than the Ni₈Ta phase which is the readily corroded major intermetallic phase in the Ni10Ta10P alloy.     

钽低温离子渗氮工艺参数对渗氮层物相的影响

利用组合的二次回归正交实验设计方案 ,对钽低温离子渗氮条件下 ,表面物相及固溶体中氮的含量随渗氮温度、气氛总压力和氢氮摩尔比的变化进行了系统研究。发现表面渗氮层由化合物Ta6N2 .57、超晶格TaN0 .1和固溶体相组成。氮在钽中的固溶度随气压、温度和氢摩尔分数的增加而增加 ,化合物和超晶格相含量随温度增加而增加 ,同时化合物相随氢摩尔分数增加有一个极大值 ,该极大值随温度增加而下降。     

Multilayer coatings by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD): TiN/TaN and TiN/W

TiN/W and TiN/TaN multilayer coatings were deposited on stainless steel by Chemical Vapor Deposition in a Fluidized Bed Reactor at Atmospheric Pressure (AP/FBR-CVD). First, the conditions for the deposition of TiN single layers were investigated, both from the experiment and thermochemical estimations. TiN was deposited from TiCl₄ and NH₃ at temperatures in the range of 750-950 °C. In the synthesis of multilayers, the W- and Ta-based layers were obtained by reduction of tungsten chloride or tantalum chloride with H₂. During the deposition of the TiN layers on top of the Ta layers, Ta reacted with NH₃ to form a mixture of tantalum nitrides. Multilayer coatings were characterized by means of GD-OES, AES and XRD. Preliminary results of nanoindentation hardness and oxidation resistance are also presented. Our results show for the first time that AP/FBR-CVD can be tuned for the deposition of multilayered coatings with periodicities in the submicron range.