A model introduction of a small amount of the Pb–Sn melt into the contact space between the sliding metal surfaces is performed. The current–voltage characteristics of the contacts of metal materials ...are obtained for the cases of the presence and absence of Pb–Sn melt between the contacting surfaces. It is shown that the electric conductance of the sliding contact is increased upon appearance of the melt in the friction zone. A simple method is proposed for calculating the electric conductance of the intimate contact in the presence of the melt and the area occupied by the melt. It is found that the dependence of these characteristics on the current density exhibits a maximum. It is shown that the electric conductance of the intimate contact in the presence of the melt is more efficiently increased by a decrease in the constriction resistance of the contact between the composite and steel than by an increase in the area occupied by the melt.
A device and express methods to analyze operating characteristics of diamond-containing composite materials in a cobalt binder have been developed. The experimental studies of the dependence of the ...diamond-containing composite material tools efficiency on intensive electric sintering have been conducted under the close-to-real operation conditions. Correlation dependences between technological parameters of sintering, microstructure, physico-mechanical properties, and operating characteristics of diamond-containing composite tool materials have been established. The ranges of variations and combinations of technological parameters of sintering, which are most promising in terms of the quality of the resultant materials, have been defined. On the strength of the data obtained an improved technology has been developed of producing segments from diamond-containing composite materials to equip tools with improved operating characteristics to be used in stone working.
The paper deals with the influence of hard anodizing coatings on ring and box spinning machines aluminum elements rubbing against the yarn upon the wear of these parts and the quality of the yarn. ...The process of hard anodic oxidation substantially increases the durability of the chosen parts of spinning frames; i.e, the spindles and rotors. For example, the wear intensity of collecting groove of the rotor without the oxides coating was found to be of 0.42 μm/h, after about 6000 h of work, while after the process of anodic oxidation it decreased to 0.0022 μm/h. On the other hand, in case of a ring spinning frame the wear intensity of the surface of the spindle coat neck without the oxides coating amounted to 0.068 μm/h, while after anodic oxidation it decreased to 0.00048 μm/h.
The paper deals with the solution of a topical problem of selecting protective ceramic materials to improve the service life of parts of gas-and-oil and other equipment that experience abrasive ...erosion. The available theoretical and experimental methods of specifying protective materials are analyzed. The author discusses the potential of the energy concept of the abrasive erosion process and uses this concept together with system approach methodology to propose new numerical characteristics. The possibility of determining these characteristics for ceramic materials by the calculation-experimental method involving a developed technique and device is shown. The availability of adequate numerical characteristics of the abrasive-containing flow and the ceramic material forms the basis for selecting a ceramic material using the criterion of its minimal wear intensity in the contaminated flow of a working fluid.
The article analyzes the properties of a thin-layer solid-lubricant coating "AIS-2", formed on the surface of a foil gas-dynamic bearing of the petal type based on a composite material "Adgelast", as ...well as the role of the components that form such coating. "Adgelast" in its physical state is a fluid, homogeneous system with a conditional viscosity 17.0-22.0 s, dry residue content 18.0-20.0%, including: high-molecular compounds, such as fluoroplast suspensions, polyamides; surfactants; organic solvents; fine fillers, pigment-soot; water. By functional purpose - it is a mono system that has many functional properties: high adhesive and cohesive strength with metal and layers of deposited composite material, respectively, resistance to high loads and pressure/hit, low tribological parameters. Composite material is applied in painting chambers equipped with inlet ventilation on a highly alloyed steel surface, prepared in advance, in several layers, by pneumatic spraying at normal temperature and pressure, thus excluding defects on the coating. Heat treatment of the applied composite material and the formation of the coating is carried out in electrical cabins at the appropriate modes. While using the x-ray phase analysis method, it was interesting to study the role of components that make up the composite material and form the "AIS-2" coating, in particular: suspensions of fluoroplastics, fillers, polyamide, as well as the role of modifying mixtures developed by us that provide a multi-component fluoroplast - polyamide system homogeneity, sedimentation and coagulation stability during long-term (years) storage and transportation, high performance and solid-lubricating properties of the "AIS-2" coating on foil gas-dynamic bearing of the petal type (support units), in aviation high-speed turbomachines.
Hard alloys of the type KKhN and KKhNF were studied and shown to have low coefficient of friction (f = 0.21-0.17) and wear rate (I = 5.7-7.0 μm/km) at sliding velocity 15 m/sec and load 7 MPa, which ...make them promising for use as antifrictional materials in dry friction units under load. Oxide films formed at the surface of the hard alloys play the role of solid lubricants and decrease frictional losses.PUBLICATION ABSTRACT
Wear of copper with different grain size (from 0.2 to 80 μm) on steel at dry friction has been studied under the following conditions: sliding velocity 0.78 m s
−1, pressure 5 MPa, and sliding ...distance 500 m. Results show that copper with submicrocrystalline structure has the lowest wear. The distribution of microhardness after friction on thickness of surface layer is described for the specimens with submicrocrystalline and coarse-grained structures Scanning electron microscopy observations were used to confirm the well-known mechanisms for ‘severe’ wear.
Tribological properties of powder composite materials of the skeletal and matrix types are studie under conditions of dry friction with rates up to 10 m/sec in air in pair with steels. Titanium ...nitride is used in order to obtain skeletons, and the matrix is polytetrafluoroethylene (PTFE). It is established that the tribological properties depend on the type of structure. In level of wear resistance materials of the skeletal type surpass by a factor of 1.5 the original compact materials, and filled PTFE by a factor of eight to nine. Use of PTFE makes it possible to improve markedly the tribological properties of composite materials based on titanium nitride and to reduce significantly (up to 40%) the weight of friction assemblies.
The influence of different deformation heat treatments on structure and wear resistance under dry sliding was studied under sliding velocity of 0.79 m/c, pressure of 0.2 to 1.0 N/mm exp 2 , and ...sliding distance of 1500 m. It was established that the deformation heat treatment led to the creation of a microcrystalline structure (2 to 3 mu m) by recrystallization in the alloy. The wear rate of the alloy with the microcrystalline structure was 1.5 to 2.0 times less and 25 to 30% less than in the beta -phase state and the initial state, respectively.
