Relationship between the structure and properties of sintered aluminum bronze base frictional materials

Conclusions The optimum combination of frictional characteristics and wear resistance under unlubricated friction conditions is exhibited by materials containing 11–14 wt.% Al in their bronze matrix. The structure of the matrix of these materials consists of a heterogeneous mixture of a ductile (an solid solution of aluminum in copper) and a brittle (the intermetallic compound Cu₂Al) component, the concentration of the latter being sufficiently low to produce no marked decrease in strength. The presence in the structure of a second phase reduces the plastic deformation of the surface layer of the material during its sliding on the mating part, results in lower temperatures being generated on the frictional surfaces, prevents the components of the frictional pair from seizing with each other and, hence, increases the wear resistance of these frictional materials.Translated from Poroshkovaya Metallurgiya, No. 9, (141), pp. 67–71, September, 1974.     

Structural and phase transformations with friction in a bronze-tungsten disulfide composite

The nature of secondary structures which form protective layers on the friction track of a (bronze - tungsten disulfide composite) — steel pair under vacuum friction conditions using a screen cooled with liquid nitrogen and the action of an additional current is studied. It is established that in all of the cases in question there is no reciprocal mass transfer of the materials in contact. A homogeneous protective layer covering the working friction surface under the action of an additional current is the interaction product of dispersed initial components of the bronze - tungsten disulfide composite and a layer of new chemical compounds of the Me₂C type with similar parameters to a high-temperature modification of the compound Cu₂S. It is assumed that formation of this compound is the result of intense pulse action of microvolumes of the material at points of contact of the body with the counterbody.Institute of Metal Physics, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, No. 4(364), pp. 30–36, April, 1993.     

Properties of composite powder coatings based on iron and ultrafine silicon nitride

Conclusions Composite-powder plasma coatings based on iron and ultrafine silicon nitride consist of a structure made up of iron matrix with inclusions of solid particles of silicon-containing compounds.The coatings have a high wear-resistance (wear rate 6.10^–11 m per l m of tracking) and are not inferior to coatings made of thermally active PN85Yul5 powders.The coatings material has a low cost, good workability with traditional methods, and demonstrates excellent working properties in actual conditions for friction units.Translated from Poroshkovaya Metallurgiya, No. 3(339), pp. 65–68, March, 1991.     

Structurization in sintering of antifriction powder materials based on iron-copper alloys

The paper studies the contact interaction of the components in powders Fe-(Cu + Sn), Fe-(Cu + Sn + P + Pb), and Fe + B-(Cu + Sn + P + Pb) during sintering in hydrogen at 920 °C. It is shown that this interaction is responsible for the formation of both the interphase boundary and the general structure that defines the performance characteristics of an antifriction material. The interface and the phase and chemical composition of the products of interaction are examined. It is established that the powder composition Fe + Cu + Sn + P + B + Pb sintered in hydrogen at 920 °C is a microheterogeneous material whose matrix, which takes up the major load during friction, includes two phases: one based on iron alloyed with boron (Fe₂B), copper, tin, and phosphorus and the other based on copper including tin in the form of α-solid solution, phosphorus in the form of Cu₃P, and iron. Lead uniformly distributed over the matrix volume is the antifriction component of the material.     

Production and properties of metal-PTFE antifriction materials from atomized bronze powders

Conclusions An investigation into the sinterability of loosely poured atomized bronze powders has established that the porosity of resultant sintered bronze skeletons depends on the particle size and shape. The shape of the bronze powder particles has some effect on the antifriction characteristics of a metal -PTFE material, but its coefficient of friction and wear resistance are affected more strongly by the composition of a solid lubricant introduced into the pores of its sintered skeleton. Using a nonspherical rather than spherical bronze powder gives a bronze saving of 15–20% without affecting the good antifriction properties of metal-PTFE materials, by increasing the porosity of their skeletons. Replacing molybdenum disulfide with graphite substantially increases the wear resistance of two-layer metal-PTFE materials and markedly decreases their cost, since the price of molybdenum disulfide is more than 20 times that of graphite.Translated from Poroshkovaya Metallurgiya, No. 9(273), pp. 30–34, September, 1985.     

Wear-resistant bronze-base composite materials produced by electric-discharge sintering

Conclusions Sintered bronze-stellite and bronze-sormite materials produced by EDS are superior in frictional properties and wear resistance to BrO10 bronze. Under conditions of friction without lubrication the advantages of such bronze-stellite and bronze-sormite materials manifest themselves most clearly at high sliding speeds (in excess of 4 m/sec). In operation with lubrication the load-carrying capacity of a sintered bronze-sormite material is two and a half times that of BrO10 bronze.Translated from Poroshkovaya Metallurgiya, No. 9(213), pp. 6–8, September, 1980.     

短碳纤维增强铜合金复合材料的摩擦磨损机理研究

采用冷压烧结方法制备了碳纤维增强铜合金复合材料(Cf/Cu-Sn-Zn)和ZQSn663锡青铜.对摩擦磨损性能进行了对比研究,并对磨损机理进行了讨论.实验结果表明,Cf/Cu-Sn-Zn复合材料的磨损率和摩擦系数低于ZQSn663锡青铜.当碳纤维体积含量达到12%时,复合材料的摩擦磨损性能达到最佳.SEM和EDS分析结果表明,ZQSn663锡青铜的磨损机制主要是黏着磨损.Cf/Cu-Sn-Zn复合材料的磨损是黏着磨损和氧化磨损共同作用的结果.     

Manufacture of small bearings from atomized powders

Conclusions Processes have been developed for the manufacture of atomized copper, tin, and bronze powders suitable for the bearings of the electric motors of domestic air conditioners. A technique has been developed for the production of small instrument journal bearings possessing good operating characteristics.Translated from Poroshkovaya Metallurgiya, No. 8(224), pp. 48–52, August, 1981.     

Effect of the content of calcium fluoride and lead on the structure evolution and the tribo-technological characteristics of a copper-based sintered material

Conclusions Calcium fluorids is a multifunctional additive. It participates in the development of the tribological characteristics, enhances the volumetric shrinkage of the materials, and prevents lead-sweating after sintering.Lead decreases the coefficient of friction of the composite materials. However, increasing its content up to 11 wt. % increases the wear of the materials abruptly. This is related to the weakening effect of lead and its distribution in the form of thin elongated layers between the grains of copper.The copper-based sintered antifriction materials containing up to 6 wt. % lead and 11 wt. % calcium fluoride have a low coefficient of friction (0.15–0.25) under the conditions of friction without lubrication; furthermore, they exhibit an insignificant wear rate (0.3–3.3m/km) and can be recommended for the high-speed friction assemblies as effective replacements for the copper-graphite materials.Translated from Poroshkovaya Metallurgiya, No. 8(344), pp. 78–83, August, 1991.     

Tribotechnical parameters for materials made from mixtures of iron and cast-iron powders

Conclusions A model has been proposed for a particular type of cast-iron powder, which relates the structure to the friction and wear.Sintering temperatures of 1100–1250°C alter the structure considerably and influence the antifriction behavior, particularly for dry friction; the inherited heterogeneity is completely disrupted by sintering only at 1250°C, which adversely affects wear resistance even if the structure is inhomogeneous at the intraparticle level.A structure containing inclusions of cementite and carbide type against the background of an elastoplastic pearlite matrix is not viable in dry friction under loads of 6 MPa or more; to improve the load capacity, it is recommended that additional heat treatment should be given to produce a martensite structure in the matrix and retain the carbide inclusions.Translated from Poroshkovaya Metallurgiya, No. 3 (339), pp. 77–83, March, 1991.     

Preparation and formability of copper phosphide Cu3P powders

A method is described for preparing Cu₃P powder by low-temperature reaction sintering from a mixture of the elements. According to thermal analysis data the phosphide forms at 470° K; particles of it assume the shape and size of the original copper powder. It is established that formability depends on the hardness and plasticity of particles rather than powder shaper and bulk density.Translated from Poroshkovaya Metallurgiya, No. 11(359), pp. 24–27, November, 1992.     

Wear-resistant powder components in continuous-casting machine friction units

It is shown that powder plane bearings can replace rolling bearings in friction units in continuous-casting machines to more than double the wear resistance.Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, No, 1 (361), pp. 97–101, January, 1993.     

Electroless tinning of copper powders

Conclusions A study was made of the tinning of copper powders from solutions. Under optimum conditions (duration 10–15 min, temperature 40°C) the process enables a tinned copper powder to be obtained of any desired tin content.Translated from Poroshkovaya Metallurgiya, No. 2(194), pp. 1–3, February, 1979.     

Dry friction and wear of alloys of diboride-nitride systems at normal temperatures

Conclusions A study was made of the room-temperature dry friction and wear of alloys of the systems ZrB₂-ZrN and HfB₂- HfN in air. It was found that all the materials investigated possess high wear resistance. The lowest values of coefficient of friction (0.3–0.4) and increased wear resistance at a sliding speed of 1 m/sec are exhibited by composites based on hafnium diboride and those containing 40–70 mole % zirconium nitride.Translated from Poroshkovaya Metallurgiya, No. 7 (103), pp. 63–67, July, 1971.     

化学气相沉积石墨烯/铜合金制备与导电、耐磨性能研究

通过原位化学气相沉积(CVD)技术,在铜粉上包覆石墨烯,再通过真空热压技术制备出石墨烯/铜合金。研究表明：铜晶粒表面包覆了高质量的石墨烯。在铜粉表面原位生长的石墨烯均匀分散在铜晶粒的晶界处,而且石墨烯的含量低,只占0.04%(质量分数)。石墨烯/铜合金具有高的导电性能,导电率高达97%IACS。同时,石墨烯/铜合金的摩擦系数降低到0.46,与铜相比降低了38.7%。石墨烯/铜合金的磨损率降低到2.09×10^-4 mm³/(N·m),与铜相比降低了68.6%。     

Effect of some additions on the microstructure and mechanical,fatigue, and friction properties of sintered lead bronze

Conclusions In an investigation into the effect of Zn, Ni, As, P, Fe, Sn, and Sb on the properties of sintered lead bronze with 30% Pb it was established that all the additions except iron and phosphorus increase in varying degrees the strength, hardness, and resistance to fatigue stresses of the material. All the additions adversely affect its coefficient of friction.Individual elements affect the properties mentioned above by changing both the structure of the bronze and the dihedral angles between its copper and lead constituents. With tin and antimony additions, dihedral angles of more than 60° are recorded; as a result, the resistance to fatigue stresses and strength of the bronze increase, but its coefficient of friction also rises.With structures characterized by dihedral angles smaller than 60°, no significant changes in properties are observed compared with the alloy without an addition; in fact, properties may actually be lowered. On the basis of the results obtained, it may be recommended that, taking into account the required load-carrying capacity and bearing life, tin or antimony should be added to lead bronze in amounts necessary for improving the friction properties of parts.Translated from Poroshkovaya Metallurgiya, No. 7 (103), pp. 98–104, July, 1971.     

Interactions of Titanium and Phosphorus with Tungsten

XRD has been applied to the component interaction in the Ti – W – P system, and an isothermal section at 1070 K has been constructed for the phase diagram in the range 0-0.67 mole fraction of P. A substitutional solid solution based on the phosphide Ti₃P is formed: Ti_3.0-2.4W_0-0.6P, a = 0.9953(2)-0.9934(3) nm, c = 0.4994(2)-0.4943(2) nm. It is confirmed that the ternary phosphide Ti_0.5W_0.5P is present of NbAs structure type. Interactions in the titanium – VIa metal – phosphorus systems are analyzed.     

Erosion resistance of some antifriction materials intended for operation in water

Conclusions In light of the investigation described in can be concluded that bronze infiltrated with PTFE holds considerable promise for operation under conditions of lubrication with hot water and without lubricant, since it possesses both high erosion resistance and good antifriction properties. It can be used, in combination with chromized surfaces, for bearings and seals in rubbing units of pumps and turbines operating at sliding speeds of up to 50 m/sec (15,000 rpm), loads of up to 2 kg/cm², lubricating water temperatures of up to 110°C, and water pressures of up to 20 atm.Translated from Poroshkovaya Metallurgiya, No. 11(155), pp. 82–86, November, 1975.     

The mineralogical characterization of tellurium in copper anodes

A mineralogical study of a «normal» commercial copper anode and six tellurium-rich copper anodes from the CCR Refinery of the Noranda Copper Smelting and Refining Company was carried out to identify the tellurium carriers and their relative abundances. In all the anodes, the major tellurium carrier is the Cu₂Se-Cu₂Te phase which occurs as a constituent of complex inclusions at the copper grain boundaries. In tellurium-rich anodes, the molar tellurium content of the Cu₂Se-Cu₂Te phase can exceed that of selenium. Although >85 pct of the tellurium occurs as the Cu₂Se-Cu₂Te phase, minor amounts are present in Cu-Pb-As-Bi-Sb oxide, Cu-Bi-As oxide, and Cu-Te-As oxide phases which form part of the grain-boundary inclusions. About 1 pct of the tellurium content of silver-rich anodes occurs in various silver alloys, but gold tellurides were never detected. Surprising is the fact that 2 to 8 pct of the total tellurium content of the anodes occurs in solid solution in the copper-metal matrix, and presumably, this form of tellurium dissolves at the anode interface during electrorefining.     

Influence of the composition of bronze-ferrochromium composites on their tribotechnical characteristics

Conclusions A bronze-5% ferrochromium composite material possesses the optimum tribotechnical characteristics in friction with lubrication, P=7 MPa, and v=1 m/sec. With an increase in ferrochromium content in the 0–10% range the hard inclusions hinder plastic deformation of the matrix. As the result there is a reduction in the capacity of the surface layers to distribute deformation under the action of contact loads in friction, that is, to run in to the abradent. Simultaneously, with an increase in ferrochromium content in the composite, the load in rubbing is absorbed to an increasing degree by the hard inclusions. With a ferrochromium content up to 5% the optimum combination of plasticity of the material and the capacity of the hard inclusions to absorb the load in rubbing is provided.Translated from Poroshkovaya Metallurgiya, No. 9(285), pp. 90–94, September, 1986.