Stress distribution in antifriction composite materials

Conclusions The optimum shape of hard inclusions in a composite material, irrespective of the magnitude of load and mode of its application to the surface, is a spheroid or ellipsoid of revolution. The characteristic linear size of a hard inclusion should be greater than the calculated diameter of a single spot of contact. If a composite material is to exhibit high fatigue strength, it is necessary to ensure that the spacing between its hard and wear-resistant inclusions is not less than (1.5–2)a (a is the characteristic linear size of the inclusions).Translated from Poroshkovaya Metallurgiya, No. 11(203), pp. 54–59, November, 1979.     

Sintered ferrous antifriction materials for arduous operating conditions

Summary The main methods by which the load carrying capacity of ferrous antifriction materials may be raised are to increase the strength of their metallic matrix by suitable alloying and to decrease their coefficient of friction by the addition of various sulfides. Researches in this field have led to the formulation of a new class of sulfidized ferrous materials. The investigation has shown that, if the load carrying capacity of a material is to be increased, the latter must contain structurally free graphite and sulfides, which secure the formation of stable working films with a low coefficient of friction. The best antifriction properties for the type of material investigated are ensured by a pearlitic-ferritic structure with a pearlite content of not more than 50%.The highest antifriction properties are exhibited by iron-graphite base materials containing 4% zinc sulfide with additions of 1% tin and 1% elemental sulfur.Translated from Poroshkovaya Metallurgiya, No. 8(56), pp. 39–45, August, 1967.     

Pb在快凝Al-Si基减摩材料中的作用

研究AJ-Si基减摩材料中Pb含量与材料力学性能和摩擦磨损特性的关系，分析了材料的微观组织，结果表明，Pb能够提高减摩性能，改善材料的摩擦磨损特性。     

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.     

Investigation of the oxidation resistance of some nickel-base materials

Summary In the investigation, a study was made of the oxidation of sintered nickel-graphite, nickel-zinc oxide, and nickel-talcum materials in air and steam environments in the temperature range 500–700°C. It is shown that the density of the material and its protection against an oxygen-containing environment circulating within its pores constitute important factors. An advantage of the nickel-zinc oxide material is the stabilization of its oxidation process, while the other materials exhibit continuous oxidation.In the course of natural tests on the nickel-graphite material in a steam turbine, the material was found to be subject to a strength loss (embrittlement), the cause of which was not discovered. However, the extent to which the properties of the material change is so small, that the latter can operate satisfactorily for two years.     

Special traits of the structure formation of alloyed antifriction materials

Translated from Poroshkovaya Metallurgiya, No. 11(359), pp. 61–66, November, 1992.     

Effect of graphite content on the antifriction properties of metallographite materials

Summary Metallographite materials containing not more than 50 vol.% graphite can be used for rubbing-friction applications at high velocities in conditions of limited lubrication. Further increase in the graphite content sharply reduces the strength of the material.With increase in the friction rate and loading, the coefficient of friction diminishes. This tendency occurs with increase in the graphite content in the structure, when a reduction in the strength of the material contributes to an increase in the wear and the growth in friction coefficient owing to the development of dispersion in the material being rubbed.The metallographite materials investigated, containing graphite in the range 50–90 vol.% under dry friction conditions,have a high coefficient of friction (of the order of 0.22–0.40) which means that they cannot be recommended as antifriction materials.In the case of operation with lubricant the metallographite materials can operate as antifriction materials with friction coefficients of 0.03–0.06 at velocities of up to 50 m/sec and with loads of up to 3.3–3.8 kgm/cm² · sec (PV=165–195 kgm/cm² · sec).