The Effect of Yttrium on Ti-5111 Gas Tungsten Arc Welds

Much interest has developed in the near-α titanium alloy Ti-5Al-1Sn-1V-1Zr-0.8Mo (Ti-5111) for naval applications. When gas tungsten arc welded with filler metal that has the same chemical composition as the base metal, however, the weld FZ tends to be harder and less ductile than the base metal, which may make the weld susceptible to failure. This behavior may be attributed to the presence of oxygen impurities and the large prior-β grain size in the weld. In this investigation, the addition of a small amount of yttrium to the weld filler metal can decrease hardening and increase the ductility of Ti-5111 welds, which is beneficial for weld performance. Microstructural and chemical analyses of unmodified and yttrium-modified Ti-5111 welds are presented along with results from mechanical testing of the welds.     

Studies and Properties of Ceramics with High Thermal Conductivity

The sintering technology of the AlN ceramics power were discussed. It is discussed that the compound sintering aids is consistent with the enhancement of the the thermal conductivity of AlN ceramics, and sintering technics is helped to the improvement of density. It is analyzed how to sinter machinable AlN ceramics with high thermal conductivity. And the microstructure of compound ceramics based on AlN was studied.     

Microstructure and Mechanical Properties of Ti-15-3 Alloy Gas Tungsten Arc Welds Prepared Using CP-Titanium Filler

Strength and ductility of fusion zone of metastable β titanium alloy welds can be improved by choosing suitable fillers. This paper reports the effects of using CP-Ti filler on the microstructural and mechanical properties of Ti-15-3 weldments. Full penetration autogenous and CP-Ti filler welds were produced by pulsed gas tungsten arc welding. X-ray diffraction analysis revealed small amounts of α-Ti phase in the diffraction pattern obtained for welds prepared using CP-Ti filler. Transmission electron microscopy analysis showed presence of grain boundary and intragranular α in the fusion zone of the welds prepared using CP-Ti filler. The welds prepared with CP-Ti filler showed higher hardness, higher UTS and lower % strain compared to autogenous welds.     

High Electrical and Thermal Conductivity Cast Al-Fe-Mg-Si Alloys with Ni Additions

Metallurgical and Materials Transactions A - Aluminum alloys with transition metals Fe and Ni show potential to form the basis for castable alloys with high electrical and thermal conductivity for...     

中国钨工业对国际钨市场的影响

分析了国际钨市场近几年来的特征,论述了中国钨工业对国际钨市场的影响,认为中国钨工业在国际上的影响越来越凸显.     

石蜡在多组元粘结剂和高比重合金喂料中的低温热脱脂动力学

为了控制热脱脂过程中的缺陷,研究了石蜡（ＰＷ）在多组元粘结剂体系和高比重合金喂料中的低温热脱脂行为。研究表明,在２５０℃以下,当保温时间相当长时,ＰＷ可以全部脱完。在此温度下,石蜡在聚合物和粉末孔隙中的扩散为石蜡的脱除速度控制,脱脂率与脱脂时间、样品厚度的倒数服从指数关系,即：１－ｍ（ｔ）ｍ（０）＝１＋Ｃ′ｅＫｄｔ。脱脂过程中产生的缺陷主要由此阶段不正确的脱脂引起     

稀土电解槽用石墨高温导热系数的测定

根据热平衡的原理 ,测定了石墨在高温条件下不同温度的导热系数 ;并根据所得数据 ,采用回归的方法 ,得到了高温状态下石墨导热系数的计算公式。     

低温离解高温自还原制备细颗粒蓝色氧化钨

研究采用仲钨酸铵作为原料,先在回转炉中200℃条件下进行低温煅烧,脱去部分结晶水与氨,再在500～750℃高温条件下利用剩余的氨进行自还原,最终制备出费氏粒度低至9.8μm的细颗粒蓝色氧化钨。研究分析了仲钨酸铵晶体在煅烧分解过程中的化学成分变化以及低温煅烧后晶体颗粒粒度与形态的变化,比较了常规的高温还原法与试验研究介绍的方法所制备的蓝色氧化钨在粒度与微观形貌上的区别。最终通过试验数据分析,该方法可以在不显著增加能耗的条件下有效地制备出费氏粒度在9～12μm的细颗粒蓝色氧化钨。     

The Role of Alloy Composition and T7 Heat Treatment in Enhancing Thermal Conductivity of Aluminum High Pressure Diecastings

The thermal conductivity of some common and experimental high pressure diecasting (HPDC) Al-Si-Cu alloys is evaluated. It is shown that the thermal conductivity of some compositions may be increased by more than 60 pct by utilizing T7 heat treatments. This may have substantial performance and cost benefits for applications where thermal management is a key design parameter.     

金属和合金中钨的光度测定进展

本文介绍了金属和合金中钨的光度测定方法的新近发展状况,论述了显色剂及其显色反应的条件,以及相应光度测定方法的检测限、干扰情况和应用。     

高速燃气热喷涂技术的进展

热喷涂是表面工程和再制造工程的重要技术支撑,其中高速燃气喷涂技术因其优良的涂层性能而应用广泛。文中介绍了高速氧气助燃火焰喷涂技术(HVOF)、高速空气助燃火焰喷涂技术(HVAF)、活性燃烧高速燃气喷涂技术(AC-HVAF),以及高速燃气电弧复合喷涂技术(HVAF-ARC)的技术特点和应用进展,并提出了高速燃气喷涂在未来的重点发展方向。     

Thermal Relaxation of Residual Stresses in Nickel-Based Superalloy Inertia Friction Welds

This article describes an experimental study aimed at characterizing the extent of residual stress relaxation during thermal treatment of inertia friction-welded alloy 720Li nickel-based superalloy welded tubular rings. In the as-welded condition, yield level tensile hoop stresses were found by neutron diffraction in the weld region along with axial bending stresses (tensile toward the inner diameter (ID)/compressive toward the outer). The evolution of these residual stress levels during postweld heat treatment (PWHT) was mapped experimentally over the weld cross section. After 8 hours of PWHT, the axial stresses relaxed by 70 pct, whereas the hoop stresses reduced by only 50 pct. Some scatter of residual stress evolution was found between samples, particularly for the axial stress direction. This was attributed to substandard tooling to grip the rings. The results on subscale samples were transferred to a full-scale aeroengine (650-mm diameter) compressor drum assembly that was postweld heat treated for 8 hours. It was found that the residual stresses, particularly in the axial direction, were noticeably lower in this full-scale weld component compared to the subscale weld heat treated for the same time. The differences seem to be best rationalized by the different standards of jigging used during joining these two types of welds.     

高强度高导电铜合金

本文综述了目前用于获得高强度高导电铜合金的几咱方法，以及该类合金的发展状况。     

超高温雾化制备球形铸造碳化钨粉末形貌控制及性能研究

传统的热喷涂用碳化钨粉末通常采用铸造方法生产,粉末呈多角状,流动性差且硬度低,难以满足高性能硬面材料的要求。以钨粉、炭黑、碳化钨粉前躯体或多角状碳化钨为原料,采用自行设计的超高温熔炼及超高温雾化装备制备出球形碳化钨粉末,利用扫描电镜、X射线衍射仪、金相显微镜、显微硬度计分析测试了粉末的相、组织、成分及性能。结果表明:碳化钨粉末外观呈球状、内部为细针状共晶组织、显微硬度3 200 HV、霍尔流速6.5 s/50 g、具有流动性好、耐磨性佳等优良的综合性能。     

硫氰酸盐分光光度法测定高铜钨精矿中三氧化钨含量

采用硫氰酸盐分光光度法测定浮选过程中高铜钨精矿时,铜对钨测定干扰严重。实验考察了硫酸联氨、甲醛、PAN指示剂(1-(2-吡啶偶氮)-2-萘酚)、DDTC(二乙氨基二硫代甲酸钠)、硫脲5种试剂对铜的掩蔽效果,其中硫酸联氨、甲醛、硫脲掩蔽效果好,因硫脲毒性低,价廉易得,实验选择作为铜掩蔽剂。实验还考察了还原剂SnCl_2或TiCl_3单独使用和联合使用的效果,单独使用SnCl_2作为还原剂,即使在70℃水浴加热10 min后显色,其灵敏度也低于室温下单独使用TiCl_3。单独使用TiCl_3与联合使用TiCl_3-SnCl_2作为还原剂灵敏度无差异,但后者稳定性更好,因此实验选择了联合使用TiCl_3-SnCl_2作为还原剂。钨含量低(w(WO_3)<1%)的样品也可以选择单独使用TiCl_3作为还原剂。     

高压坯强度钨粉工艺研究

压坯强度是反映粉末质量优劣的重要指标之一。以BTO(蓝色氧化钨)、PTO(紫色氧化钨)、YTO(黄色氧化钨)按一定配比进行混合作为原料,通过调整料层厚度、升温速度、氢气露点、高温带中停留时间等工艺参数制得了分散性强和表面形貌优良的粉末,并使用这些粉末制备了压坯,结果表明压坯强度有了很大的提高。     

Microstructures of Hardfaced Overlay on Low Carbon Steel by Gas Tungsten Arc Melt Injection of Diamond Grits

Ni-coated diamond grits were injected into hardfaced Ni-based alloy overlay on a low carbon steel substrate as reinforcing particles with a gas tungsten arc melt injection method. Microstructures of the hardfaced overlay were investigated with scanning electron microscope, energy dispersion spectroscopy and X-ray diffraction analyzer. The results showed that the Ni coating on the injected diamond grits was sound and the diamond grits were not damaged thermally. A very thin layer of TiC formed on the interface between the diamond and the Ni layer. In the overlapped region of the multi-passes specimen, the diamond grits injected in the previous pass were damaged thermally, while the ones injected in the successive pass were not.     

Thermal Conductivity of Powder Aggregates and Porous Compacts

A new equation for calculating the thermal conductivity of metal powder aggregates and sintered metal powder compacts is proposed. In this equation, the effective conductivity of the powder system is a function of the conductivity of the fully dense material, the porosity of the system, and the tap porosity of the starting powder. The new equation is applicable to powder systems, from the tap porosity to zero porosity, as well as to consolidated powders. The proposed equation has been experimentally validated by fitting to data from other authors. The results confirm a good agreement with theoretical predictions.     

高锡钨精矿选择性浸出锡、钨工艺研究

研究了采用高压碱浸法从高锡钨精矿中分离锡、钨,考察了浸出温度、碱浓度、浸出时间、液固体积质量比及添加剂用量等对锡、钨浸出率的影响。结果表明:将750℃下焙烧2h的高锡钨精矿进行高压碱浸,在添加剂用量为矿石质量的1.0%、温度150℃、氢氧化钠用量为理论量的3倍、浸出时间2.5h、液固体积质量比1∶1条件下,钨浸出率达98.57%,浸出渣中锡质量分数为3.34%;锡富集于浸出渣中,钨进入溶液,钨、锡得到有效分离。