钽表面渗氮层的氧化行为

进行了钽表面预先离子渗氮对其后续表面高温熔盐阳极化过程及性能影响的试验研究。发现钽表面预先离子渗氮并不改变其后表面阳极化处理的动力学过程控制步骤,但表面膜层生长速度减慢。膜层物相由钽的氧化物变为氮化物。膜层静态电阻率增大;致密性更好。表面粗糙度低,耐碱腐蚀性能提高。     

利用SOM法制备金属钽

在熔盐MgF2-CaF2中以预烧成型的Ta2O5为阴极，氧化钇稳定氧化锆管内的碳饱和铜液为阳极，利用固体透氧膜（SOM）法直接电解还原Ta2O5制备了金属钽。在3．5V电压下，研究了不同温度下阴极产物的形貌及其对脱氧的影响，分析了电流随时间变化的规律。结果表明：随着电解温度的升高，脱氧速度加快，金属钽颗粒尺寸明显增大，其形貌由海绵状向块状转变；当温度为1423K时，具有较好的金属钽制备效果。     

氟化物熔盐体系中锆的电沉积

<正> 锆极易生成表面氧化膜,对酸、碱具有极好的耐蚀性能,尤其对碱性溶液的耐蚀性优于钽、钛和不锈钢。然而锆材价格较昂贵,因此,采用电镀的方法来制备锆镀层具有重要的现实意义。锆的析出电位较析氢电位负得多,其电还原过程只能在熔盐体系中进行。Senderoff及其同事曾研究了锆及其它难熔金属的熔盐电镀,他们的研究表明锆能从氟化物熔盐     

钽基复合材料

钽基复合材料美国ＬｏｓＡｌａｍｏｓ国家实验室新近开发成功一种耐蚀性极高的新型复合材料Ｔａ－Ｔａ２Ｃ复合材料，解决了传统耐蚀材料都难以应付的象氯气、某些熔盐和熔融金属（钙、钚等）之类苛腐蚀环境中的耐蚀性问题。这种钽基复合材料可用于各种熔盐／熔融金属系统...     

钽在溶盐中阳极氧化膜的组织和性能

对钽在高温硝酸盐中阳极氧化所形成膜的组织和性能进行了研究。试验结果表明，膜层基本上是由钽的氧化物相构成。该膜层具有高的硬度和良好的抗碱腐蚀性能。     

电弧离子沉积钽膜及微结构研究

目的研究电弧离子沉积钽膜的沉积工艺及微观结构,分析钽膜生长机理。方法采用电弧离子沉积法在石墨基体上沉积钽膜,研究了沉积工艺(如弧电流、负偏压等参数)对钽膜的物相组成、沉积速率、表面形貌的影响。结果电弧离子沉积钽膜的物相由α-Ta相和极少量β-Ta相组成。弧电流、负偏压、靶间距等沉积参数对钽膜厚度、沉积速率和膜-基结合力的影响很大,在弧电流为220 A、负偏压为300 V、靶间距为200 mm时,钽膜沉积速率为0.1μm/min,沉积速率适宜,膜-基结合力达到69 N,结合力高。钽膜厚度均匀,在靠近基体侧形成了晶粒细小、组织致密的过渡层,厚度约0.6~0.9μm,其余为细小柱状晶结构。钽膜表面颗粒尺寸随负偏压的升高而减小,负偏压为300 V时,颗粒尺寸细小均匀(仅3~5μm),钽膜表面无细小孔隙和裂纹。结论电弧离子沉积法可以在石墨基体上沉积出组织致密、厚度均匀且膜-基结合力高的钽膜。沉积初期主要通过沉积、移动、扩散等过程形成稳定核,随着沉积时间的延长,稳定核逐渐长大成岛,并在三维方向以岛状生长形成连续膜,为典型岛状生长模式。     

粘胶纤维钽喷丝头熔盐阳极化表面处理及应用

喷丝头是化学纤维纺丝机上的关键零件。本文对钽喷丝头表面在高温熔盐中阳极化强化的工艺技术进行了研究,试验结果表明,在合适的熔盐温度、阳极化电压、电流及阳极化时间等工艺参数条件下,喷丝头阳极化处理后在其表面形成了高硬度并耐碱腐蚀的改性层,这一改性层的存在使得喷丝头的抗变形、抗划伤和耐碱腐蚀性能大大地提高,纺丝性能亦有所改善。阳极化强化的钽喷丝头已应用于生产实践,可取代黄铂金喷丝头,使生产成本降低。     

电容器用铌粉和钽粉制备技术的进展

综述了铌粉和钽粉的现行生产工艺及几种新的还原方法，介绍了金属热还原反应中的电化学反应机理。钽粉的现行生产工艺几乎都用亨特法，铌粉则大部分采用铝热还原法生产。通过对亨特法还原条件、稀释剂组成等各种工艺参数的改进，已经可以制备纯度高、形态可控的金属钽粉。铌粉新还原方法的研究主要包括金属预成形热还原法、镁等蒸气还原预成形氧化物粉末的方法、镁或钠的蒸气还原氯化物蒸气的气相还原法、以液氨为介质在低温液相中均相还原铌或钽的氯化物的方法、反应媒介熔盐在强搅拌条件下的液体镁热还原金属氧化物的方法等。     

粘胶纤维钽喷丝头熔盐阳极化表面处理及应用

喷丝头是化学纤维纺丝机上的关键零件。本文对钽喷丝头表面在高温溶盐中阳极化强化的工艺技术进行了研究，试验结果表明，在适合的熔盐温度、阳极化电压、电流及阳极化时间等工艺参数条件下，喷丝头阳极化处理后在其表面形成了高硬度并硬耐碱腐蚀的改性层，这一改性层的存在使得喷丝头的抗变形、抗划伤和耐碱腐蚀性能大大地提高，纺丝性能亦有所改善。阳极化强化的钽喷丝头已应用于生产实践，可取代黄铂金喷丝头，使生产成本降低。     

钽在强腐蚀环境中的应用

钽的独特性能使难熔金属在当今先进加工技术的应用中具有很强的优势。钽的耐蚀性类似于玻璃，因而在化学和药物加工中，成为一种可选材料。 钽在化工行业中的优势 在2000多种化学试剂中，钽仅被40种试剂所腐蚀，即仅仅被破坏氧化膜(层)的化学试剂所腐蚀，如强碱，含游离的SO3或SO2的发烟硫酸、氟气、氢氟酸及含氟离子超过10ppm的溶液。浓度超过10%的NaOH、KOH溶液也腐蚀钽，并导致氢脆。下表中对比了钽和AISI316型不锈钢的机械性能。两种材料的硬度相似，316型不锈钢略占优势。钽比不锈钢更软些，这使其更利于维修和元件设计。 钽和A…     

Phase evolution of tantalum nitride and tantalum carbide films with PBII parameters

Tantalum nitride and tantalum carbide films were fabricated using magnetron sputtering of tantalum followed by nitrogen and carbon plasma-based ion implantation (N-PBII and C-PBII). The phase evolution and morphology of the films were studied using glancing angle X-ray diffraction (GXRD) and transmission electron microscopy (TEM). It was found that the main phase in the tantalum nitride films was crystalline TaN_0.1 whose grain size increases with increasing implantation voltage and phase content increases with increasing implantation dose. In the tantalum carbide film, the main phase was Ta₂C. TaC phase also appeared as the implantation dose increased. XRD results from various glancing angles show that the phases with high nitrogen or carbon content, Ta₄N₅ and TaC, are present in the surface of the films. X-ray photoelectron spectra (XPS) from the tantalum carbide film reveal that the surface carbon content is higher than that of the inner film.     

钽在熔盐中阳极氧化膜的组织和性能

对钽在高温硝酸盐中阳极氧化所形成膜的组织和性能进行了研究。试验结果表明 ,膜层基本上是由钽的氧化物相构成。该膜层具有高的硬度和良好的抗碱腐蚀性能     

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。     

一种提高MPCVD法制备金刚石膜均匀性的方法

采用自制的1 kW石英钟罩式微波等离子体化学气相沉积装置,以氢气和甲烷作为气源在镜面抛光的(100)面单晶硅片上沉积了金刚石薄膜。实验共制得两个样品,其中一个样品在制备的过程中加装了难熔的金属钽环,利用等离子体易吸附于金属钽环表面的特性,缩小了硅片中间与边缘等离子体密度差异,另外一个样品没有加装难熔的金属钽环。利用激光拉曼光谱仪和扫描电子显微镜(SEM)对制备的样品进行了表征,发现没有加装金属钽环的样品中间位置沉积的金刚石膜质量明显高于边缘位置沉积的金刚石膜,中间位置、离中间5 mm位置、边缘位置沉积膜层的厚度差别很大;加装了金属钽环的样品中间位置与边缘位置沉积的金刚石膜质量差不多,中间位置、离中间5 mm位置、边缘位置沉积膜层的厚度差别不大,上述结果证明金属钽环的加入是一种提高MPCVD法制备金刚石膜均匀性的方法。     

硫酸甲醇体系中电解抛光钽的实验研究

采用硫酸甲醇体系对钽进行电解抛光,并对其抛光性能进行了研究,测定了不同配比时电解液中钽的阳极极化曲线,研究了电解液配比和电压对钽表面质量的影响.在搅拌速率为16 m/s、电解液温度为0℃、时间为3 min、硫酸甲醇体积比为1:7时,电压在20 V左右抛光效果较好、钽表面均方根粗糙度Rq小于30 nm,不仅能够满足钽材表面精饰加工需求,而且能够满足EOS靶用标准材料薄膜对表面质量要求.     

Effect of tantalum film on corrosion behaviour of AA6061 aluminium alloy in hydrochloric acid- and chloride-containing solutions

ABSTRACT

The present work is concerned with the corrosion resistance of AA6061 aluminium alloys with tantalum films in hydrochloric acid- and chloride-containing solutions. The tantalum films were produced by magnetron sputtering at different sputtering times (50 and 120 min). The films’ morphologies were observed by metallographic microscope and scanning electron microscope with energy dispersion spectrum. It is shown in this paper that with longer sputtering time, the film’s thickness increased, but it became less dense. The corrosion behaviour was characterised by potentiodynamic polarisation, scanning electrochemical microscopy analysis and an immersion experiment. These investigations revealed that the corrosion resistance of AA6061 aluminium alloy in chloride ions medium and hydrochloric acid was significantly improved after deposition of a tantalum film. Specifically, samples deposited for 50 min exhibited the best corrosion resistance in hydrochloric acid, while samples deposited for 120 min showed best corrosion resistance in sodium chloride solution.     

Characterization of air-formed surface oxide film on Ti-29Nb-13Ta-4.6Zr alloy surface using XPS and AES

The surface oxide film on a Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) was precisely characterized using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) to understand the composition and chemical state of the surface oxide film of TNTZ. For comparison, the component metals, titanium, niobium, tantalum, and zirconium, were also characterized to consider the effect of those on the formation of the surface oxide film on their alloy. The characterization of the surface oxide films on TNTZ and its component revealed the following issues. The surface oxide film on TNTZ consists of a composite oxide that contains titanium, niobium, tantalum, and zirconium but forms continuous layer and is very thin, ca. 3.7 nm. The oxide film is not completely oxidized because it contains various valences of cations. In particular, the oxidation of tantalum is inhibited in the oxide. Tantalum is enriched in the substrate in TNTZ just under the surface oxide because of this inhibition in the oxidation. The formation of the surface oxide film in TNTZ is predominantly governed by titanium. The preferential oxidation of an element is not always dependent on the initial oxidation potential of that element, the relationship between the oxidation energy from a smaller valence to a larger valence, and the dehydration process. In other words, a complicated competition governs the resultant composition of surface oxide.     

Effect of pH on the Electrochemical Behavior of Tantalum in Borate Buffer Solutions

In this research, various electrochemical methods were used to investigate the electrochemical behavior of tantalum in borate buffer solutions of various pH values, ranging from 9.0 to 6.5. Potentiodynamic polarization curves revealed that tantalum showed excellent passive behavior in borate buffer solutions. The potentiodynamic polarization and electrochemical impedance spectroscopy results showed that the passive film formed on tantalum offered its best protective behavior when the pH is 8.0, with the passivity undergoing a drastic change as the pH moved toward higher values. The semiconductive behavior of the passive films formed on tantalum was investigated by employing Mott-Schottky analysis in conjunction with a point defect model. The results indicated that the passive film exhibited n-type semiconductive behavior and that donor densities were in the range of 1.958-7.242 × 10²⁰ cm^?3. Moreover, this analysis showed that the donor density and flat band potential were quite sensitive to the pH.     

The corrosion behavior of amorphous nickel base alloys in a hot concentrated phosphoric acid

The corrosion behavior of more than 50 melt-spun alloys was examined in an 87 wt% H₃PO₄ solution at 433 K. Ni-(30–50)Ta alloys possess the highest corrosion resistance due to the formation of a hydrated tantalum(V) oxyhydroxide film containing a small amount of phosphate. Corrosion rates of Ni-(1–10)Ta-P, Ni-(15–20)Cr-P and Ni-(10–20)Mo-P alloys are comparable to that of crystalline tantalum metal. The corrosion resistance of the former two alloy families is based on the formation of tantalum(V) phosphate and chromium(III) phosphate, respectively. The surface film on the Ni-Mo-P alloys consists of molybdenum(VI) and Ni(II) oxyhydroxides and phosphates, and nickel oxyhydroxide seems more protective than molybdenum oxyhydroxide.     

钽涂层多孔钛合金支架的制备与表征

钽金属是一种理想的医用金属材料,能够与人体软/硬组织发生整合。利用化学气相沉积方法,在可控多孔结构的Ti6Al4V合金支架表面沉积涂覆钽金属涂层,使其同时具备理想的三维孔隙结构和力学相容性,以及钽金属优异的生物学性能。研究结果显示,多孔钛合金支架表面涂层前后色泽发生明显变化,涂层后支架呈现钽金属色泽。扫描电镜和XRD分析进一步证明了多孔钛合金支架表面沉积物为钽金属。与美国Zimmer公司生产的多孔钽小梁金属相比,钽涂层多孔钛合金支架具备与人体皮质骨更相似的弹性模量和抗压强度,是一种理想的骨修复替代物。