Observations of the Effects of Oxide Skins on the Oscillations of Electromagnetically Levitated Metal Droplets

The surface tensions of liquid metals can be derived from measurements of the natural oscillation frequencies of levitated drops through the Rayleigh relation, In general, during terrestrial measurements, a spectrum consisting of three to five dominant oscillation frequencies (in the range of 30 to 60 Hz) are found, rather than the single one predicted by Rayleigh, due to deformation of the drop shape by gravity and the supporting magnetic field. Cummings and Blackburn have derived a correction factor to align the measured frequencies with the Rayleigh frequency, which has been shown to hold through micro-gravity experiments by Egry et al., for the majority of metals that have a liquid surface. Work at the NPL on more complex, commercial alloys has found that, in some cases, oscillation frequencies may be split into more complex spectra exhibiting seven to nine oscillation frequencies. This has been attributed to formations of oxide from the metal collecting on the surface of the droplet. Observations of the frequency spectra and high speed video images of the levitated drops are discussed.     

铝合金扁锭宽面竖状皱褶缺陷的成因

介绍了铝合金扁锭出现竖状皱褶缺陷的某些规律，分析了竖状皱褶缺陷产生的原因及其防止的途径，并进行了防止竖状皱褶缺陷的现场试验.     

液氯连续汽化系统中三氯化氮的富集条件

利用ChemCAD软件模拟计算了液氯连续汽化后三氯化氮重新在氯气缓冲罐中富集的临界条件,为确定液氯连续汽化工艺指标提供了参考依据。     

冷拌SBS沥青液在修补坑槽中的应用

结合吉壶二级公路水毁修补工作实践，简述了SBS沥青液的技术指标要求及特点，介绍了SBS沥青液在修补坑槽中的施工方法，并总结了有关注意事项，以使对水毁病害的处治收到较好的效果。     

改进酚醛树脂液的粘度测量

在树脂磨具制造中，树脂液的粘度是一项重要指标。因此，树脂磨具厂要测量树脂液的进厂粘度及存放过程中的粘度变化。本文介绍了改进树脂液粘度的测量方法和涂4^#杯的结构，以提高测定的准确性，并以测量酚醛树脂液的粘度-温度关系为实例，分析了改进的效果。结果表明，用机械搅拌代替人工搅拌后相对误差可从1．96％降至0．5％，再采用仪器恒温后还能把最大误差从5．40％降至1、80％，     

铁液质量热分析仪的功能特点及发展

本文介绍了热分析仪的原理、功能特点、技术发展;在铸铁生产中的在线检测、控制作用.     

Role of temperature gradient in liquid／solid phase solution-diffusion bonding

The liquid-film solution-diffusion bonding of ZCuBe2. 5 alloys was conducted using Cu-based alloy powders. The tensile strength of the joint is up to 318 MPa. With the increase of temperature gradient, the bonding time decreases and the interlace migration velocity increases remarkably. The appropriate temperature gradient is 5 -40 K/cm. Under fixed bonding time, the thickness of diffusion layer increases with the increase of temperature gradient, and this tendency becomes more remarkable with the prolonging of bonding time.     

Bonding of Al2O3 ceramic and Nb using transient liquid phase brazing

The brazing of Al2O3 to Nb was achieved by the method of transient liquid phase (TLP) bonding. Ti foil and Ni-5V alloy foil were used as interlayers for the bonding. The base materials were brazed at 1423-1573 K for 1-120 min. The results show that the shear strength of the joint first increases and then decreases with increasing holding time and brazing temperature. The joint interface microstructure and elements distribution were investigated. It can be concluded that a composite structure, in which the base metals are solid solution Nb(V) and Nb(Ti) reinforced by Ni3Ti, is formed when the brazing temperature is 1473 K and holding time 15 min, and a satisfactory joint strength can be achieved. The interaction of Ti foil and Ni-5V foil leads to the formation of liquid eutectic phase with low melting point, at the same time the combination of Ti come from the interlayer with O atoms from Al2O3 results in the bonding of Al2O3 and Nb.     

Influence of alloy ingredients on mechanical properties of ternary boride hard alloy clad materials

Using Mo, B-Fe alloy and Fe powders as raw materials, and adding C, Cr and Ni ingredients, respectively, or C, Cr and Ni mixed powders, ternary boride hard alloy clad materials was prepared on Q235 steel substrate by means of in-situ reaction and vacuum liquid phase sintering technology. The influence of alloy ingredients on the mechanical properties of ternary boride hard alloy clad materials was investigated. The results indicate that a mixture of 0.8% C, 5% Cr and 2% Ni ingredients gives a ternary boride hard alloy clad material with optimal mechanical properties, such as high transverse rupture strength, high hardness and good wear resistance.