铌基超高温合金熔体与陶瓷类坩埚的高温反应

分别在陶瓷类ZrO2、Y2O3、BN和Al2O3坩埚内于2053K（或2153K）保温30min（或10min）重熔铌基超高温合金（主要组分为Nb、Si、Ti、Hf等），以研究该合金的高温熔体与不同材料坩埚的反应情况。实验发现Y2O3、BN和Ai2O3坩埚对熔体都发生了不同程度的沾污反应；在ZrO2坩埚壁上出现了50～60μm厚且具有微小裂纹或熔蚀坑的反应层，其内含有HfO2和TiO2，但ZrO2坩埚对熔体内部基本没有污染。在石墨坩埚上进行制备YSZ涂层的实验发现，ZrO2同石墨基体发生反应生成了ZrC0因此，据有关实验结果，可以先在石墨坩埚基体上用CVD法制备一层SiC内层，再在SiC内层上用浸涂法制备ZrO2涂层，以用于铌基超高温合金熔炼。     

The growth of Cu-Sn intermetallics at a pretinned copper-solder interface

This article reports a comparative study of the formation and growth of intermetallic phases at the interface of Cu wetted with a thick solder joint or a thin, pretinned solder layer. The η phase (Cu₆Sn₅) forms when Cu is wet with eutectic solder at temperatures below 400 °C. The intermetallic layer is essentially unaffected by aging at 70 °C for as long as 13 weeks. On aging a eutectic joint at 170 °C, the η-phase intermetallic layer thickens and ε phase (Cu₃Sn) nucleates at the Cu/intermetallic interface and grows to a thickness comparable to that of the η phase, while a Pb-rich boundary layer forms in the solder. The aging behavior of a thin, pretinned eutectic layer is qualitatively different. At 170 °C, the Sn in the eutectic is rapidly consumed to form η-phase intermetallic, which converts to ε phase. The residual Pb withdraws into isolated islands, and the solderability of the surface deteriorates. When the pretinned layer is Pb-rich (95Pb-5Sn), the Sn in the layer is also rapidly converted into η phase, in the form of dendrites penetrating from the intermetallic at the Cu interface and discrete precipitates in the bulk. How ever, the development of the intermetallic largely ceases when the Sn is consumed; ε phase does not form, and the residual Pb remains as an essentially continuous layer, preserving the solderability of the sample. These observations are interpreted in light of the Cu-Sn and Pb-Sn phase diagrams, the temperature of initial wetting, and the relative diffusivities of Cu and Sn in the solder and intermetallic phases. A.J. SUNWOO, Formerly with the Lawrence Berkeley Laboratory, Berkeley, CA,     

钼镧合金板材高温抗下垂性能的研究

以粉末冶金法生产的180 mm×20 mm×1.5 mm钼镧合金板材为试验原料,通过对比轧制和高温定型处理制备的钼镧合金板材在1 750℃高温和500 g重物荷载条件的下垂值,并研究了这两种板材的组织形态。结果表明:采用常规工艺轧制的钼镧合金板材组织纤维发达,而采用了高温定型处理后的钼镧合金板材形成了一种粗大、组织相互搭接的再结晶组织;在1 750℃高温及500 g重物的载荷条件下,高温定型后的钼镧合金板材的下垂值较小,其下垂值从常规工艺轧制的钼镧板的4.2 mm减小到1.8 mm,表现出良好的高温抗下垂性能。     

Very High Cycle Fatigue of Ni-Based Single-Crystal Superalloys at High Temperature

Very high cycle fatigue (VHCF) properties at high temperature of Ni-based single-crystal (SX) superalloys and of a directionally solidified (DS) superalloy have been investigated at 20 kHz and a temperature of 1000 °C. Under fully reversed conditions (R = ? 1), no noticeable difference in VHCF lifetimes between all investigated alloys has been observed. Internal casting pores size is the main VHCF lifetime-controlling factor whatever the chemical composition of the alloys. Other types of microstructural defects (eutectics, carbides), if present, may act as stress concentration sites when the number of cycles exceed 10⁹ cycles or when porosity is absent by applying a prior hot isostatic pressing treatment. For longer tests (> 30 hours), oxidation also controls the main crack initiation sites leading to a mode I crack initiation from oxidized layer. Under such conditions, alloy’s resistance to oxidation has a prominent role in controlling the VHCF. When creep damage is present at high ratios (R ≥ 0.8), creep resistance of SX/DS alloys governs VHCF lifetime. Under such high mean stress conditions, SX alloys developed to retard the initiation and creep propagation of mode I micro-cracks from pores have better VHCF lifetimes.     

Nb-Ti-Al高温铌合金氧化行为研究

研究了Nb-35Ti-6Al、Nb-15Ti—llAl以及Nb-30Ti-15Al三组合金于900℃和1000℃在空气中的氧化行为，建立了Nb-Ti—A1合金高温氧化动力学模型。研究表明，元素Ti和Al的加入能有效改善合金的抗氧化性能，合金中占相的存在降低了氧的溶解度。同时抑制氧的扩散，因而两相合金Nb-15Ti-llAl和Nb-30Ti-15Al（β＋δ相）抗氧化性能优于单相合金Nb-35Ti-6Al（β相）。     

高速电气化铁道用铜锡合金接触线的开发

介绍了采用连铸连轧工艺生产φ20mm铜锡合金线坯的过程,分析了线坯氧含量、锡含量对生产稳定性的影响。阐述了拉拔机冷拉成型接触线的工艺过程,对产品的抗拉强度、延伸率等性能指标进行了研究及对比。     

高速电气化铁道用铜锡合金接触线的开发

介绍了采用连铸连轧工艺生产φ20mm铜锡合金线坯的过程,分析了线坯氧含量、锡含量对生产稳定性的影响.阐述了拉拔机冷拉成型接触线的工艺过程,对产品的抗拉强度、延伸率等性能指标进行了研究及对比.     

高温合金表面激光熔铸镍基合金涂层的组织与耐磨性能

研究了高温合金ＧＨ３３表面激光熔铸镍基合金涂层的组织和耐磨性能。结果表明,基材对涂层合金的稀释作用较小;涂层与基材之间形成良好的冶金接合;涂层基体组织为γ－Ｎｉ枝晶,枝晶间为γ－Ｎｉ、Ｍ２３（ＣＢ）６、Ｎｉ３Ｂ、Ｃｒ２Ｂ、ＣｒＢ、ＷＣ等;涂层耐磨性能的平均值较基材提高４倍以上。     

Sensitivity to Stress Concentration of Steel at High Temperature

Thesurfacetransversalcrackonacontinuouscastingslabisthoughttoberelatedtothedefectsontheslabsurfacesuchasthelardandthevibrationtraceontheinnerarcsideofslab ,anditgeneratesinthesecondarycoolingzoneofcontinuouscastingpro cess .Inordertodeterminethedeformationtemper atureofslabinthesecondarycoolingzoneofthecontinuouscastingprocess ,thethermalplasticityofsteelismeasuredinthermalmechanicalsimulatorus ingcontinuoussampleontheassumptionthatthecontinuouscastingslabisauniformandcontinuousonewithoutanydef…     

几何结构影响高温空气燃烧特性的数值分析

通过改变燃料喷口周围空气喷口分布夹角,采用数值计算的方法研究了高温空气燃烧特性的变化,包括燃烧温度场、速度场和NOx的生成和出口排放情况。模拟结果说明,减小空气分布夹角可以降低燃烧区最高温度和平均温度,扩大燃烧室内低氧范围,有效抑制热力型NOx的生成和排放。所采用的计算模型和计算方法可以较好地模拟高温空气燃烧过程,计算结果可信。     

两种镍基合金涂层抗高温氧化性能研究

对自行研制的新型高铬镍基合金 (w(Cr) >40 % )涂层和传统的镍铬合金 (Ni70Cr30 )涂层在 6 5 0℃和80 0℃下的高温氧化动力学规律进行了研究。采用配有能谱分析仪的扫描电镜以及X射线衍射仪等对氧化产物的形貌和相组成等进行了分析。两种镍基合金涂层均表现出较好的抗高温氧化性能 ,尤其是由新型高铬合金制备的涂层 ,其表面生成了连续的Cr2 O3 保护膜 ,具有更低的氧化速度     

含Cu钢连铸高温延塑性研究

含Cu钢因具备良好的强度、耐蚀性、焊接性能,被广泛地应用于船舶、压力容器、石油生产平台及工程机械。但由于选择氧化,Cu在钢表面富集,易导致含Cu钢在生产过程出现热裂纹。针对含Cu钢的这一特性,采用热拉伸试验研究了Cu含量对钢高温塑性的影响,对相同Cu含量、不同Ni含量的钢种热塑性也进行了对比,并结合其显微组织及断口形貌对试验钢种的脆性断裂机理进行探讨。同时,还利用Thermocalc软件计算了试验钢种的塑性低谷对应温度,提出了含Cu钢的连铸工艺优化建议。     

高风温长寿热风炉的设计

介绍了不同形式热风炉的特点和结构稳定性,针对鞍钢4号高炉增建4号热风炉采用的新技术－近似悬链线拱顶、烟气分配、冷风分配、圆形火井、板块结构、滑动缝、膨胀缝、不锈钢隔板、七孔格子砖以及组合砖等进行了介绍,同时对在有预热技术的情况下,有效地提高风温问题进行了探讨。     

Relationship between Thermodynamic Parameters for Mn-Fe Melt and Temperature

The carbon solubility in Mn Fe melts were measured at 1 350℃ , 1 375℃, 1 425℃and 1 450℃, and accordingly the calculated equations were obtained. By thermodynamic derivation and calculation, some relationships between thermodynamic parameters for Mn-Fe melt and temperature were obtained.     

熔体测温中热电偶保护材料的性能探讨

本文从传热学、热力学的角度,分析了在高温氧化工况下,对材料性能的要求,探索选择优良的热电偶保护套管材料,以期有效地测量及控制熔体的温度。     

连铸坯的高温力学性能分析

探讨了影响连铸坯高温力学性能的因素,提出制定合理的连铸工艺制度必须以钢的高温力学性能为基础,控制板坯的表面温度,避开第Ⅲ脆性区;必须考虑钢种成分的影响,以有效减少铸坯裂纹的发生,提高铸坯质量.     

金属氧化物陶瓷涂层高温阻氘渗透性能研究

采用射频磁控溅射方法在316L不锈钢表面沉积了 Al2O3,Cr2O3,Y2O3和ZrO2(8％Y2O3)4种单层氧化物陶瓷涂层.选用X射线衍射(XRD)和扫描电镜(SEM)对4种氧化物陶瓷涂层相组成、微观组织结构进行表征,结果表明,Al2O3涂层为非晶态,其他3种氧化物陶瓷涂层均为晶体结构,且涂层沉积致密,无明显微观...     

二噁英高温气相生成机理研究进展

介绍了二噁英的高温（500～800℃）气相生成机理，气相生成与合适的前驱物有关，是气相中氯苯和氯酚等氯代前驱物在温度高于500℃热解重排结果，燃烧系统中自由氯的产生和高浓度的氯代苯氧基生成，随后在碳环上发生二聚反应取代氢，导致了二噁英的生成，因此控制焚烧炉较好的燃烧条件，如保持焚烧炉燃烧室足够的燃烧温度（不低于850℃）及气体停留时间（不少于2s），可以减少二噁英的气相生成。     

Superplasticity of Directionally Solidified NiAl-15Cr Alloy at High Temperature

Ni-25Al-15Cr (atomic percent, %) alloy was directionally solidified (DS) under argon atmosphere in an Al2O3-SiO2 ceramic mold by standard Bridgman method. The microstructure of the as-fabricated alloy was studied using optical microscope, X-ray diffractometer, and scanning electron microscope. The alloy consisting of dendritic β-NiAl phase, interdendritic γ/γ′ phase, and transient layer γ′ phase, has been investigated. This alloy exhibits superplastic deformation behavior at 1 273-1 373 K over an initial strain rate range of 8.35×10-4-1.67×10-2 s-1. The maximum elongation of 280% with strain rate sensitivity index m=0.22 was obtained at the temperature of 1 323 K and an initial strain rate of 8.35×10-3 s-1. Transmission electron microscopy (TEM) observations indicate that the superplastic deformation stems from the balance between high resistance (by dislocation sliding) and strain softening (by dynamic recovery and recrystallization).