内嵌式钨铜粉末爆炸复合结构材料的研究

为满足托克马克核聚变装置内壁材料对W-Cu复合材料的需求,提出了内嵌式粉体爆炸复合方法和技术工艺。先用该方法制备内嵌式W-Cu粉复合材料,其实验粉末分别采用粒径3μm与23μm的纯钨粉和添加10%铜粉的W-Cu混合粉末(质量分数)。然后利用扫描电子显微镜、显微硬度计对内嵌式W-Cu粉复合材料进行表征、分析。结果显示,实验粉末经过爆炸烧结压实后能达到90%以上该密实材料的密度。添加10%铜粉后制备的W-Cu粉复合结构材料结合界面更加规则均匀理想,结合界面附近几乎没有孔隙,粉末压实部分孔隙度更小且孔隙的尺寸更小,均匀致密性更好,但粉末压实层硬度更低。使用粒径3μm的混合粉末与23μm的混合粉末,后者制备的W-Cu粉复合材料,粉末压实部分均匀致密性更好,孔隙度更小且孔隙的尺寸更小,粉末压实层密度更大,但硬度更低。     

内嵌式钨铜粉末爆炸复合结构材料的研究

为满足托克马克核聚变装置内壁材料对 W-Cu复合材料的需求,提出了内嵌式粉体爆炸复合方法和技术工艺。先用该方法制备内嵌式W-Cu粉复合材料,其实验粉末分别采用粒径3μm与23μm的纯钨粉和添加10%铜粉的W-Cu混合粉末(质量分数)。然后利用扫描电子显微镜、显微硬度计对内嵌式 W-Cu粉复合材料进行表征、分析。结果显示,实验粉末经过爆炸烧结压实后能达到90%以上该密实材料的密度。添加10%铜粉后制备的 W-Cu粉复合结构材料结合界面更加规则均匀理想,结合界面附近几乎没有孔隙,粉末压实部分孔隙度更小且孔隙的尺寸更小,均匀致密性更好,但粉末压实层硬度更低。使用粒径3μm的混合粉末与23μm的混合粉末,后者制备的 W-Cu粉复合材料,粉末压实部分均匀致密性更好,孔隙度更小且孔隙的尺寸更小,粉末压实层密度更大,但硬度更低。     

汽车继电器用AgMeO触点材料不同配对方式时的性能

为了探究触点配对方式对汽车继电器电接触性能的影响,选取AgMeO型触头材料进行实验,采用粉末冶金法制备AgSnO₂, AgCuO和AgZnO 3种触头材料,并测量其物理性能,采用JF04C电接触触点材料测试系统,按5种不同触点配对方式进行电接触实验,并对实验前后的阴阳极触点进行称量,实验结果表明：触点配对方式对接触电阻,材料转移和损耗影响较大,对燃弧能量的影响较小,通过对触点进行不对称配对可以明显降低接触电阻和材料转移和损耗,明显改善汽车继电器的接触性能.     

Influence of the tip effect of a carbon nanostructure on low current electrical arc initiation

During their setting off, circuit breakers and vacuum switch devices are accompanied by an electric arc whose physical and chemical properties are governed by emissive current sites at the cathode surface called cathode spots. Assuming the continuity of the current on the cathode surfaces, the cathode spots contribute to supply the electrical arc by electron emission and material ejection. Thus they cause erosion on the contact electrodes inducing a dysfunction of contactors. The apparition of these cathode spots is due essentially to dust particles and surface irregularities at different scales. This experimental work represents a contribution to the understanding of the electrical arc behaviour by an investigation at submicronic scale on the influences of nanostructured carbon tips on the electric arc initiation and the cathode spots birth.     

超细钨铜复合粉末注射成型药型罩研发及测试

W-Cu合金结合了钨的高密度与铜的高动态延伸率,是一种前景广阔的药型罩材料.为获得性能优良的金属射流,提高油气井射孔弹的穿孔指标,对高致密均质W-Cu合金药型罩进行了研发.采用热化学工艺开发了不同含铜率(质量分数为10%,15%,20%,25%)的亚微米级超细W-Cu复合粉末,选W-25Cu型复合粉末并采用注射近净成型工艺技术制备了药型罩,将脱脂件在H_2气氛中烧结,峰值温度为1 200℃.采用SEM观察发现,烧结药型罩微观结构为亚微米级的W粒子均匀地分布在Cu基体中,其实测密度高达14.75 g/cm~3.拉伸试验表明,所开发的药型罩材料具有优良的力学性能,极限抗拉强度达到822.4 MPa,屈服强度达807.5 MPa,延伸率为1.18%.破甲性能测试实验证明,该类药型罩具有极其稳定的侵彻性能.     

Investigation and analysis of arc ablation on WCu electrical contact materials

In this paper, arc ablation behavior of tungsten–copper (WCu) alloy contacts was investigated by the measurement of weight-loss, or erosion rate, and microstructures of tungsten–copper alloy contacts were examined by using scanning electron microscopy after electrical breakdown process. Experimental results showed that the arc erosion process started at the tiny sharp edges, then the arc spreaded on the second phases, or copper phase on the surface. Because of electrons/ions bombardment, the rapid evaporation and sputtering of liquid copper droplets were serious. As a result, an even contact surface became rugged, and tungsten skeleton remained because of being less eroded. With the increase of applied breakdown voltage, the ablation of tungsten–copper alloy became more significant. The WCu alloys with a higher content of copper showed more severe erosion rate as compared with that with a higher tungsten content under the same erosion conditions. Furthermore, when the number of breakdown is less, WCu alloys with a high copper content are easier for erosion for the conditions of fewer numbers of breakdowns. Whereas, WCu alloys with a high content of tungsten are easier for ablation for the conditions with many times of arc breakdown.     

Densification of pure magnesium by spark plasma sintering-discussion of sintering mechanism

In this study, high-quantity pure magnesium was prepared by SPS, and the sintering densification mechanism was discussed by using numerical simulation and simultaneous experiment. Results show that a layer of dense magnesium oxide was formed at the surface of Mg particles, and the oxide reduction can be observed owing to the effect of oxide film removal in SPS. The high energy pulsed current flows preferentially through particle contact surfaces, which provides the conditions for the generation of micro-arc between particles and the temperature at the particles contact point can be up to 1979 °C. With the low pressure at the initial sintering stage, local high temperature induced by micro-arc makes the melting (even evaporation) appearance. At the same sintering temperature of 570 °C, the obvious difference in bending strength also demonstrates the significance of spark discharge in SPS. The formation process of sintering neck demonstrates that sintering process is the reflection of melting (even evaporation), diffusion and plastic deformation. In order to realize tiny area and high-quality connection between powder particles, an innovative powder sintering technology using high-frequency pulse electric current (High frequency pulse current assisted sintering) is proposed based on the enlightenment of the skin, proximity and arc discharge effect of high-frequency pulse current. This technology is also instructive for other alloys and engineering materials.     

利用W-Cu梯度层连接93W合金与无氧铜的实验研究

针对“面向等离子体元件”对W—Cu复合材料的需求,进行了利用W—Cu梯度层连接93W合金与无氧铜的实验研究。首先选用Zn作为烧结助剂,采用粉末冶金方法热压烧结了不同W含量的W-Cu梯度层,研究了烧结温度、W含量对其致密度和微观结构的影响,确定了适宜的烧结条件为温度1123K,压力20MPa,保温时间60min。在该条件下制备的W-Cu梯度层的致密度大于96％,其物相为W、Cu,二者以机械混合形式共存。在此基础上,通过在93W合金与无氧铜之间加入三层W含量逐渐变化、无宏观界面的W—Cu梯度层,在梯度层致密烧结的同时,实现93W合金与无氧铜的连接。     

低温球磨制备纳米晶铝/铝基复合材料的研究进展和应用前景

详细介绍了国内外采用低温球磨粉末冶金法制备纳米晶铝及其铝基复合材料的研究进展。通过对比分析国内外在材料研制和工装设备研发等方面存在的主要差距,提出了国内在纳米晶铝应用研究中存在的问题、解决措施及发展方向。最后,对纳米晶铝/铝基复合材料未来的应用前景进行了展望。     

钨粉颗粒形貌对钨铜合金药型罩破甲性能的影响

为了研究钨粉形貌对钨铜合金药型罩破甲性能的影响,采用了4种不同颗粒形貌的钨粉,利用机械合金化法和冷等静压旋压工艺制备钨铜合金药型罩,并对钨铜合金药型罩射孔弹进行了地面静破甲穿钢靶试验,通过试验分析钨粉形貌对钨铜合金药型罩破甲性能的影响。结果表明:钨粉颗粒完整、形貌为多面体的钨粉,其松装密度达到9.564 g/cm³,制备的钨铜合金药型罩的破甲深度达到338.3 mm,破甲稳定性达到99.21%;而钨粉颗粒有缺陷、形貌为类球状的钨粉,其松装密度仅为7.142 g/cm3,制备的钨铜合金药型罩的破甲深度达到338.3 mm,破甲稳定性达到99.21%;而钨粉颗粒有缺陷、形貌为类球状的钨粉,其松装密度仅为7.142 g/cm³,制备的钨铜合金药型罩的破甲深度为288.1 mm,破甲稳定性为92.7%,分别下降了17.4%和7.6%。     

A corrosion study on W-Cu alloys in sodium chloride solution at different pH

A corrosion study of two types of tungsten-copper(W-Cu)alloys in 3.38 wt.%Na Cl solution with different pH at 25℃were investigated using potentiodynamic polarization and immersion test.It is crucial that the corrosion behavior and preferential attacked phases of the W-Cu alloys were found to alter with p H.The micro-galvanic effect of tungsten phase and copper binder played a significant role.It was also proved that the existence of aggressive chloride ions could accelerate the Cu binder dissolution in acidic and neutral solution,which induced tungsten phase detachment and increased the corrosion rate of the W-Cu alloys.While Cl-would accelerate the Cu binder dissolution of W-Cu alloys at high potential during polarization test in strong alkaline solution.     

Sintering of nanostructured W-Cu alloys prepared by mechanical alloying

Nanostructured (NS) powders with compositions corresponding to W-20wt%Cu and W-30wt%Cu were prepared by mechanical alloying. The microstructure and grain size of as-milled and annealed powders were analyzed by transmission electron microscopy. The compacted specimens were sintered at temperatures in the range 1000 °–1300 °, and then the microstructures of sintered parts were analyzed by scanning electron microscopy. Sintering of mechanically alloyed W-Cu alloys appears to be independent of Cu content, and may be explained in terms of recovery and grain growth in the mechanically alloyed powders as well as impurity activated sintering of W. After sintering, Cu pools are formed outside the mechanically alloyed powders. A relative sintered density of more than 95% is obtained by particle rearrangement during liquid-phase sintering, and the greatest homogeneity of W and Cu phases is achieved by sintering at 1200 °.     

W80/Cu-Al_2O_3复合材料的耐电弧侵蚀性能

采用粉末冶金和熔渗法制备W80/Cu-Al_2O_3复合材料,测试其密度、硬度和导电率,探究Al_2O_3对W80/Cu复合材料耐电弧侵蚀性能的影响。结果表明,添加Al_2O_3对复合材料的致密度和导电率影响不大,硬度有所增加;W80/Cu和W80/Cu-Al_2O_3复合材料在不同电流条件下燃弧时间和燃弧能量基本相同,但W80/Cu-Al_2O_3复合材料的稳定性更高;在30 V、30 A条件下,W80/Cu复合材料在电弧侵蚀过程中发生材料从阴极向阳极转移,加入Al_2O_3增强相后,材料的转移方向为阳极向阴极转移,且材料损耗量降低,喷溅现象减少,电弧侵蚀后触头表面更加平整。     

载流摩擦磨损中影响起弧的因素分析

以铜基粉末冶金/铬青铜为摩擦副,在销-盘式摩擦磨损试验机上进行了载流摩擦学特性研究。在多种试验条件下对载流摩擦磨损中影响起弧的因素进行了分析。结果表明,载荷主要是通过影响接触状态和摩擦副表面温度,进而影响材料的电弧性能。载荷有一个最佳值,在此载荷条件下燃弧率、电弧能量、摩擦系数、质量磨损率均最小;电流在两电极间产生电场是形成电弧放电的必要条件,电流主要影响了摩擦副的表面温度,从而使摩擦副表面状态变差。     

Cathode spots on the surface of nanostructured W alloys

The tracks of cathode spots produced after arcing on the surfaces of nanostructured W alloys were investigated using a scanning electron microscope (SEM). For nanostructured W–2%ThO₂ cathodes, the distribution of cathode spots was dispersed and their geometrical properties were completely controlled by the shape and size of ThO₂. For nanostructured W–20%Cu cathodes, the spots were also separated on Cu-rich phase. The results showed that cathode spots on the surface of nanostructured W alloys were quite different from those on the surface of commercial W alloys with coarse grain size, and the microstructure of the cathode materials had significant influence on the cathode spots propagation. Also, space-charge regions induced by internal electric field at the interface which responded to the effect of microstructure on cathode spots were suggested.     

钨铜合金的最新研究进展及其应用

综述了近年来国内外钨铜合金材料制备技术方面的主要进展，并介绍了最新研制成功的几种新型钨铜合金材料，如梯度钨铜材料、纳米钨铜材料等，以及钨铜合金在民用和军事工业上的主要应用，并简要地探讨了钨铜合金今后发展的主要动向和研究重点。     

高纯Ti2AlC粉末的无压制备及其在Ag基电触头材料的应用

Ag基电触头是低压开关的“心脏”, 触头无Cd化一直困扰着人们, 寻找新型环保电触头材料是目前低压开关领域研究的重点。本研究从Ag基电触头增强相材料设计入手, 利用简单快速的无压技术合成了高纯Ti₂AlC粉末(99.2%), 制备的Ag/Ti₂AlC复合电触头材料组织均匀、Ti₂AlC颗粒与Ag基体结合紧密、相对密度高(95.7%)、硬度适中(96HV)、导电性好(电阻率低至79.5 nΩ·m)、抗电弧侵蚀性能优良(5610次电弧放电后触头质量损失仅为4.4wt%)。Ag/Ti₂AlC优良的结构和性能主要归因于Ti₂AlC本身的导电导热性能和Ag/Ti₂AlC之间的润湿性。该复合材料在进一步深入研究后, 有望大面积应用并替代传统电触头材料。     

Preparation and properties of Al2O3 dispersed fine-grained W-Cu alloy

In this study, high-performance fine-grained W-Cu sintered blocks with the addition of dispersed Al₂O₃ particles were successfully produced by low temperature liquid-phase sintering, using the raw material of ultrafine W-Cu alloy powder. The ultrafine W-Cu alloy powder was obtained by a two-step reduction process composed of stages of carbothermal reaction and hydrogen deep deoxidation. The fine Al₂O₃ grains with uniform distribution in W-Cu alloy were introduced by spray method, leading to the decrease of W grain size and W-W connectivity. The relative densities of all sintered blocks were>97%, and a higher degree of densification ensures that the alloy has excellent comprehensive properties. With the increase of Al₂O₃ content, W grain size and W-W connectivity of sintered W-Cu samples decrease from 664 nm to 472 nm and 0.2 to 0.14, respectively. The W-Cu alloy with the ultimate tensile strength of 415 MPa and the highest elongation of 7.22% was obtained when the addition amount of Al₂O₃ was 0.5 wt%. At the same time, it also possessed the maximum bending strength of 1028 MPa and microhardness of 312 HV, respectively. In addition, due to the good network structure of Cu and uniform three-phase distribution, the sintered samples had excellent conductivity and compressive strength.     

钨铜梯度材料热震过程中显微组织及热性能

针对目前W-Cu功能梯度材料(FGM)在长期热震循环过程中的稳定性缺乏相应研究的问题,以化学镀W-10wt%Cu复合粉体和Cu粉为原料,通过叠层压制和常压气氛烧结的工艺制备了W-10wt%Cu/W-20wt%Cu/W-30wt%Cu层状梯度材料。在600℃、800℃、1000℃温度下进行热震试验,对试样在不同热震温度、热震次数下的显微组织和热学性能变化进行了研究。试验结果表明,随着热震温度升高,渗出至试样各梯度层表面的Cu逐渐增加。当热震温度达到1000℃时,试样各梯度层表面出现大量Cu聚集成片的现象,同时在W-20wt%Cu/W-30wt%Cu界面处发现了界面裂纹。随着热震次数的提高,在W-10Cu层中,Cu逐渐渗出表面并在内部留下微孔。此外,W-Cu FGM的热导率随热震次数的增加而减小,在1000℃经过200次热震后,室温热导率由200.54 W·(m·K)?1降至159.23 W·(m·K)?1,降低了20.60%。该结果揭示了热震循环中裂纹形成与显微组织变化的耦合失效机制,明确了W-Cu FGM安全服役的范围。      

Copper Alloys From Metal Oxide Precursors for High Conductivity Applications

Extrusion of oxide powders allows fabrication of thin-walled metal articles to produce controlled-geometry, low-density copper alloy architectures. Shapes formed with copper oxide powders mixed with alloying oxides are reduced and sintered to produce high relative densities in the thin walls. This technology has produced square-cell honeycomb extrusions, which are being characterized for heat sink applications. This effort is to determine the bulk properties of alloys produced by this type of thermo-chemical powder processing and to explain behavior based on the final chemistry and microstructure of the alloys. Compositions investigated include Cu, Cu-Ni, Cu-Ag, W-Cu, Cu-Invar, Cu-Al₂O₃, and Cu-Cr alloys. Alloys have been characterized for relative density, thermal conductivity, and grain size. Mechanical properties including tensile and yield strength and elongation were measured on Cu-Ni and Cu-Ag, and the results were analyzed based on porosity and composition of the alloys. Properties were compared to alloys made through conventional processing and powder metallurgy.