热处理对自力型整体式W-Cu/QCr0.5电触头材料组织与性能的影响

用烧结熔渗法制备W-Cu／QCr0．5自力型整体电触头材料，采用扫描电镜(SEM)和X射线衍射仪(XRD)分析固溶时效处理前后的组织与性能的变化。结果表明，固溶时效热处理后，伴随着铜尾电导率和硬度的明显提高，钨铜合金头的组织分布更加均匀、致密，两者的结合强度也得到改善。     

Influence of laminar lubricants on the structure,character of failure,and properties of silver-base electrical contact materials

Translated from Poroshkovaya Metallurgiya, No. 6(354), pp. 58–69, June, 1992.     

Erosion behavior and structure of silver-intermetallic compound electrical contact materials

Conclusions The action of an arc discharge on a contact made of a silver-intermetallic compound composite material is accompanied by selective erosion in the affected zone, which is a result of the anchoring of the arc discharge to particles of the intermetallic compound — a phase of comparatively low thermal conductivity. A characteristic feature of the selective erosion is a nonuniform structure of the affected zones of contacts, the nonuniformity increasing in intensity with rising volume concentration and T_m of the intermetallic compound. On contacts of hypoinversion compositions the character of structural nonuniformity in the affected zone on the cathode is different from that on the anode, but on contacts of hyperinversion compositions the affected zones on the cathode and anode exhibit the same type structural nonuniformity. There is a tendency for the functions of the cathode and anode to become equalized in the supply of eroded material to the arc gap. Increasing the current shifts the composition boundary between the ranges in which different types of cathode erosion are observed and hence the inversion range toward lower intermetallic compound contents. The structural nonuniformity of affected zones gives rise tospike formation during the excitation of electrical discharges between stationary contacts. The greatest propensity forspike formation is exhibited by refractory intermetallic compound-containing composites of hyperinversion composition. During erosion testing the rate of erosion varies, being a maximum at the beginning of testing. The fall in and subsequent stabilization of erosion rate are brought about by accommodation of the surface layers of contacts and by the formation in these layers of a structure exhibiting optimum resistance to erosion.Translated from Poroshkovaya Metallurgiya No. 9(213), pp. 28–34, September, 1980.     

Process and compressive properties of porous nickel materials

Abstract

Compressive properties are investigated for the porous Ni materials processing by innovated powder metallurgical (PM) method. The porous Ni materials first show a short elastic region, then a long and oblique stress yield region within the strain range of about 10–50%, and finally, a densification region where the stress increases rapidly.     

Effects of oxide particles on properties of sintered nickel

Conclusions The effect was investigated of the addition of aluminum, zirconium, silicon, and hafnium oxides on the hot hardness and rupture strength of nickel at temperatures of 600–800°C. The rupture strength of nickel is shown to increase with increasing amount of oxide introduced into it and with decreasing oxide particle size. In tests below the temperatures at which transformations take place, the nature of the oxides investigated does not affect the properties of nickel.Translated from Poroshkovaya Metallurgiya, No. 6 (78), pp. 81–86, June, 1969.     

Fe掺杂对纳米Ag-SnO_2电接触合金润湿性及电性能的影响

采用座滴法研究Fe掺杂对Ag与纳米SnO2之间润湿性的影响,进一步利用化学共沉淀和常压烧结法制备掺杂Fe元素的Ag-SnO2电接触合金,对该合金进行耐电压和模拟电弧侵蚀试验,并通过冷场发射扫描电镜(FESEM)及X射线能谱仪(EDS)分别对其在电弧侵蚀前后的形貌和成分进行观察和分析。结果发现,Fe的加入使Ag与纳米SnO2之间的润湿性提高,但掺杂含量达到一定值(Sn与Fe的原子比为14:5)后,增加掺杂量对润湿角影响不大。所制备的电接触合金呈现纳米第二相弥散均匀地分布在Ag基体中;随掺杂元素Fe含量增加,合金的耐电压强度提高,表面发生的局部熔化和Ag液集中喷溅现象明显减轻。     

银钨合金W分离回收工艺的研究

以银钨合金为研究对象,提出了从钨基合金废料中回收W的工艺流程,考察了焙烧、硝酸浸取以及煅烧等过程中工艺条件对分离效果和回收率的影响.试验证明在适当的条件下,银的浸出率可达到99%以上,从而保证了钨的分离和回收效率.     

Corrosion of sintered electrical contact materials under the conditions of the tropical marine climate

Conclusions The results yielded by this investigation into the corrosion properties of composite materials support the hypothesis advanced in [2], according to which their dissolution behavior obeys the principle of independence of electrochemical reactions. At any given potential each phase in a composite corrodes at a rate characteristic of this phase regardless of processes involving other phases. The process of corrosion of each phase is controlled solely by the latter's condition and composition, which in turn are determined by the reaction of the individual components during the manufacture of the material. When the conditions of operation of a composite material and the corrosion resistance of its components, as affected by their interaction, are known, the corrosion of the material can be expected to be determined by the corrosion of its components.Translated from Poroshkovaya Metallurgiya, No. 2(170), pp. 39–43, February, 1977.     

Structure and properties of sintered iron-graphite materials alloyed with nickel and phosphorus

Summary A study was made of the influence of alloying with nickel and phosphorus on the structure and properties of sintered iron-graphite materials. The structural study was carried out by x-ray and electron diffraction methods, and in addition the wear resistance and strength characteristics of the materials were determined.Translated from Poroshkovaya Metallurgiya, No. 3 (51), pp. 52–55, March, 1967.     

热喷涂Ag/Cu复合触头涂层组织及性能

分别采用等离子和高速电弧喷涂系统制备了Ag/Cu复合触头涂层,利用扫描电镜、划痕试验仪、显微硬度仪、双电桥法以及真空电弧烧蚀仪等分析测试了Ag/Cu复合触头涂层的组织及性能。结果表明:DH-X2等离子喷涂制备的Ag/Cu复合触头涂层孔隙、裂纹少,显微硬度范围89.7～106.1 HV,涂层与基体结合的临界载荷79.2 N,电导率68.5%IACS,截流值1.0A、燃弧时间2.6ms;而QD8高速电弧喷涂制备的涂层组织结构疏松,涂层内部有较大裂纹,并出现银氧化物相,显微硬度范围为58.3～74.6 HV,涂层与基体结合的临界载荷57.2 N,电导率53.7%IACS,截流值1.4A、燃弧时间2.7ms。DH-X2等离子喷涂制备Ag/Cu复合触头Ag涂层比QD8高速电弧喷涂制备的涂层组织及性能更加优异。     

Microstructural modelling of electrical conductivity and mechanical properties of sintered ferrous materials

Abstract

The role of microstructure on mechanical properties of sintered ferrous materials was studied using a method based on electrical conductivity measurement. The method was accompanied by quantitative fractography to evaluate the dewaxing and sintering process in iron compacts. The effects of manufacturing parameters, such as compacting pressure in the range of 150–800 MPa, sintering temperature from 400 to 1300°C, sintering time up to 8 h, and lubrication mode were investigated. Several mathematical models were checked to obtain the best one for prediction of electrical conductivity changes as a function of manufacturing parameters. The mechanical properties of the sintered compacts were also evaluated to establish a relationship between conductivity, total porosity, pore morphology, and mechanical behaviour. The results show that the electrical conductivity/resistivity of sintered materials is closely related to its microstructure, so that measuring these properties can replace destructive test methods for prediction of mechanical strength of sintered materials with homogeneous matrix microstructure. The application of the method is shown for sintered Fe, Fe–0·8%C, and Fe–1·5%Mo–0·7%C compacts.     

Structure and properties of powder metallurgy chromium sintered by the electrical contact heating method

Translated from Poroshkovaya Metallurgiya, No. 3(327), pp. 34–39, March, 1990.