掺钴镁新型线切割钼丝的制备

介绍了一种掺钴镁新型线切割钼丝的制备方法。在二氧化钼粉中加入钴、镁元素,经粉末冶金和机械加工制作出用于电火花线切割加工的钼合金电极丝。不仅改善了线切割用钼丝的高温性能、抗拉强度、放电效率和抗损性能,而且提高了其应用价值。     

A study of high-velocity combustion wire molybdenum coatings

In this paper, coatings manufactured using the high-velocity combustion wire (HVCW) spray process have been studied. Molybdenum coatings were prepared in this study, and wavelength dispersive x-ray analysis (WDX) investigations were carried out to ascertain the oxygen content of the coating and its distribution. The x-ray diffraction (XRD) analysis of the coating was also carried out to determine the phases present in the coating. Based on the above data, the authors explain the HVCW-sprayed molybdenum coating microstructure properties. These coatings were also sprayed using a modified aircap design. The parameters varied for the molybdenum coatings by HVCW and were (1) the distance of the substrate from the spray gun and (2) the wire feed rate of the gun. The wear test and coefficient of friction measurements were also carried out for the coatings. Air plasma spraying of Mo-25% NiCrBSi coatings was carried out, and these coatings were further checked for wear friction properties.     

钼及钼合金研究的进展

简述了具有高性能的纳米钼粉、高纯钼粉的制备方法,包括微波等离子法、电脉冲法和球磨法;介绍了钼钛锆合金、钼铼合金、稀土钼合金、Si-Al-K掺杂钼合金、钼硅合金、钼铜复合材料的强化机制和研究现状,并展望了钼及其合金未来的发展。     

退火温度对超细钼丝性能的影响

通过调整退火温度测试不同温度下超细钼丝的力学性能,探讨退火温度对超细钼丝力学性能影响的规律,从而制定钼丝最佳退火工艺。结果表明,在900．1100℃退火,超细钼丝的延伸率变化不明显,而在1100～1350℃退火,延伸率发生了突变;结合断口分析得知,900～1100℃退火主要发生回复,未消除加工形成的轴向织构,而1350℃退火,超细钼丝发生了再结晶,完全消除了加工织构,所以综合性能得到改善。依此推荐超细钼丝最佳连续退火工艺参数为：在氢气保护下,移动速度为10m／min,加热温度在1350℃左右。     

钼镧合金板材料舟的研制及其断裂行为分析

研究掺杂稀土镧的钼粉经压型、烧结、交叉换向轧制而成的钼镧合金板热冲压钼舟变温变载下的力学行为,探讨高温退火后析出物的弥散分布对钼镧合金板材力学性能的影响及加热制度对合金板材冲压成型性能的影响,分析料舟的断裂机制.研究表明,弥散分布的La2O3明显提高了钼板再结晶温度与力学性能,交叉轧制降低了板材纵向和横向力学性能的差异,有利于钼镧合金板的冲压成型;对2.8 mm厚Mo-1.0％La2O3合金板及冲压模具在550℃进行加热,将得到最大的冲压变形量;钼舟在18管炉内承受变温变载荷长期运行后,由于材料内部的空位迁移与滑移面上的位错滑移导致的韧窝撕裂,使料舟最终发生了宏观断裂.     

热处理温度对镧钼丝组织与性能的影响

系统研究了纯钼丝和镧钼丝在不同温度下进行热处理后的组织与性能。结果表明，La2O3是镧在钼丝中的唯一存在形式，镧的添加，提高了丝材的室温强度和再结晶温度，改善了再结晶后的室温脆性，其综合性能明显高于纯钼丝。     

Effect of La_2O_3 nanoparticles on properties of molybdenum powder

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Producing composite single-crystal molybdenum mirrors by diffusion welding in the hot isostatic pressing conditions

Experiments were carried out to develop methods of diffusion welding of joints between single-crystal molybdenum and polycrystalline molybdenum through a titanium interlayer in the hot isostatic pressing (HIP) conditions. The structure and the mechanical and physical properties of the diffusion welded joints Mo_single + Ti + Mo_poly were investigated. Composite molybdenum single-crystal mirrors with areas of 5000 and 8000 mm² were produced and subjected to successful tests.     

钼丝研究现状

钼丝作为一种重要的钼制品,拥有十分广阔的发展前景,主要应用于线切割行业、喷涂钼丝行业等,但是在制备和使用过程中存在着成丝率低、断丝率高、寿命短等问题,纯钼丝已经无法满足现代工业发展的要求,各种掺杂钼合金丝日益得到重视,对纯钼丝、TZM合金丝、Al-Si-K掺杂钼合金丝、Mo-Re合金丝、稀土掺杂钼丝、Mo-Al2O3合金丝及多元复合掺杂钼丝的制备方法和研究现状进行了综述,并对钼丝在研究过程中存在的问题进行了讨论、分析和展望。     

La2O3对Mo粉性能影响的研究

采用光电子能谱分析方法对掺杂La2O3的Mo粉的性能进行了研究，结果表明：掺杂La(NO3)3的MoO2粉经过还原处理后，Mo粉表面的纳米La2O3微粒可以减小Mo基体的特征能量损失峰，增加Mo3d光电子谱峰强度，由于纳米LaO3粒子在金属Mo的表面及周围对Mo起到包埋效应，减小了Mo与大气的接触面积，从而使Mo的抗氧化能力增强。     

Eliminating Molybdenum from Sodium Tungstate Solution by Selective Precipitation

Eliminating Molybdenum from Sodium Tungstate Solution by Selective Precipitation     

在低温熔盐LiTFSI-CsTFSI中电沉积钼

研究了在二元二(三氟甲基磺酸酰)亚胺碱金属盐LiTFSI-CsTFSI的共晶熔体(共晶点组成：摩尔比为0.07:0.93; 共晶点温度为112 ℃)中电化学沉积难熔金属钼。结果表明,选择MoCl3作为钼离子源,分别于200和150 ℃在镍基体上电沉积得到金属钼。循环伏安法结合SEM和XPS分析表明,在1.4 V vs. Li+/Li处的恒电位电解所得到的沉积物为非晶态的金属钼     

超细钼粉制备技术的研究现状与进展

金属钼因低的热膨胀系数、高温强度、高弹性模量等特性,广泛用于航空航天、军工、石油化工以及核工业等尖端行业,是推动高科技领域发展不可或缺的材料。钼粉作为钼制品的基础原料,其物化性质与钼制品的性能密切相关。相比于普通钼粉,超细钼粉具有更大的比表面积、更高的活性以及更低的烧结温度。目前制备超细钼粉的方法主要有热还原法和热分解法,热还原法通过调整还原工艺达到阻止晶粒长大的目的;而热分解法的发展主要涉及到装备的升级改造与工艺的优化完善。本文着眼于超细钼粉的制备工艺、反应机理以及产物状态,重点分析了典型工艺的发展历程和技术特点,总结了超细钼粉制备技术的研究现状与进展,提出当前技术工艺所面临的问题以及未来的研究方向,以期为超细钼粉制备工艺的发展与工业化应用提供思路。     

中厚纯钼板轧制工艺实验研究

中厚纯钼板在交叉轧制中,存在工艺难以控制、轧废率高及退火后性能不均匀等现象。因而,寻求合理的轧制和退火工艺对降低成本、提高产品质量有重要意义。通过实验研究表明:中厚纯钼板在25%的道次压下率、退火温度850℃下能得到较好的综合性能。     

钼基掺杂合金的研究现状

合金化是改善钼性能的主要途径。本文对固溶强化类、弥散强化类及K泡强化类钼合金进行了综合评述,重点从制备方法、形貌组织、强化机理以及力学性能这几个方面,对TZM合金、Mo-Re合金、La2O3掺杂钼合金、Al2O3掺杂钼合金以及Si-Al-K掺杂钼合金这几类合金的研究现状进行了分析。根据钼合金抗氧化性能差和耐磨性能差这两个缺点,提出了研制抗氧化涂层和硬质相是未来钼合金发展的两个重要方向。     

基于热加工图的钼金属热变形特征研究

通过热压缩试验研究钼金属在应变速率为0.01～10 s-1,变形温度为900～1450 ℃条件下的热变形性能,建立了基于流变应力的钼金属热变形的本构方程.综合考虑应变速率和变形温度对材料微观结构及性能的影响,根据动态材料模型(DMM)建立了钼金属的热加工图,并利用加工图确定了热变形时的流变失稳区,分析了不同区域钼金属的高温变形特征.     

气流磨处理对钼粉物理性能的影响

研究了微型流化床对撞式气流磨处理对普通钼粉物理性能的影响。气流磨处理后,钼粉的松装密度、振实密度大幅提高;钼粉粒度分布变窄、d50明显减小;通过SEM分析发现,钼粉颗粒形貌均匀、团聚体全部被打开。另外经气流磨处理,适当调节分级器转速,可以在一定的范围内有效地调节钼粉的费氏粒度。总之,气流磨处理是改善钼粉物理性能的一种有效方法。     

Formation of molybdenum boride cermet coating by the detonation spray process

The effects of the powder particle size and the acetylene/oxygen gas flow ratio during the detonation spray process on the amount of molybdenum phase, porosity, and hardness of the coatings using MoB powder were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The results show that the presence of metallic molybdenum in the coating results from decomposition of MoB powder during thermal spray. The compositions of the coatings are metallic Mo, MoB, and Mo₂B, which are different from the phases of the original powder. The amount of molybdenum phase increases monotonously with the oxygen/acetylene ratio, but the increasing rate for the fine powder is faster than that for the coarse powder. The porosity and hardness of the coating are related to the amount of molybdenum phase. The phase constitution of the coating is discussed.     

On the recrystallization behavior of technically pure molybdenum

In the last decades the amount of interstitial impurities in the raw material used for powder metallurgical production of molybdenum has been reduced significantly. The quality of the production process has been adapted to the latest technological standards and, consequently, the properties of technically pure molybdenum have changed accordingly. For processing pure molybdenum and to predict the resulting mechanical properties, the recrystallization behavior, which strongly depends on the concentration of the prevailing impurities, e.g. carbon, nitrogen and oxygen, is decisive. A reliable recrystallization diagram of molybdenum was published in 1965, which does not accurately describe the recrystallization behavior of the current quality of technically pure molybdenum. Therefore, in the present investigation a diagram which reflects the static recrystallization behavior of molybdenum containing low concentrations of interstitial impurities was established. The recrystallization behavior has been monitored on differently deformed and subsequently heat-treated samples by means of hardness testing, light microscopy and scanning electron microscopy employing electron channeling contrast imaging (ECCI) and electron back scatter diffraction (EBSD). Especially ECCI and EBSD investigations offer the possibility to analyze the change of microstructure with regard to recovery and recrystallization effects, e.g. the evolution of subgrains. The quantity of the impurities was determined by standard chemical analysis methods. As a bcc metal, molybdenum exhibits a high stacking fault energy. Thus, the recrystallization behavior is strongly dominated by concurrent recovery processes, which deviate from that of fcc metals showing a comparably low stacking fault energy. A revised recrystallization diagram for technically pure powder metallurgically processed molybdenum is presented.     

Reaction mechanisms of low-grade molybdenum concentrate during calcification roasting process

The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The results show that calcium-based additives can react with molybdenum concentrate to form CaSO₄ and CaMoO₄. The initial oxidation temperature of MoS₂ is 450 °C, while the formation of CaMoO₄ and CaSO₄ occurs above 500 °C. The whole calcification reactions are nearly completed between 600 and 650 °C. However, raising the temperature further helps for the formation of CaMoO₄ but is disadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows the order: Ca(OH)₂>CaO>CaCO₃. With increasing the dosage of Ca(OH)₂, the molybdenum retention rate and sulfur-fixing rate rise, but excessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca(OH)₂ to molybdenum concentrate is 1:1. When roasted at 650 °C for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grade molybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% with calcines being leached by sulphuric acid.