International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The effect of metal phase composition in the Fe-based + (2 % glass) powdered composites on the basic mechanical and tribological properties of the composites, made by means of sintering and hot forging, have been investigated. As a basis for the metallic phase of the composite the mixtures of iron powders with additives of graphite, B₄C, BN and Cu at different ratio were used. It was shown that at sintering of metal-glass material the reaction of glass phase with oxides on the surface of iron powder particles takes place, resulting in a change of glass phase chemical composition. The results of materials mechanical properties investigations had shown that the highest strength properties and hardness have the composites with the content of the initial powder mixture of 5% Cu and 2% B₄C, while the best tribological properties have the composites with 2% B₄C, 5% Cu and 1% BN.

In this paper was investigated the formation of complex diffusion boride layers on metastable austenite Cr-Mn-N steel powder method. Calculate the value of the diffusion coefficient in different physical – chemical conditions and the thermodynamic potential chemical reactions. Defined phase composition layers obtained on the metastable austenite Cr-Mn-N steel. It is established that the application of an external magnetic field (EMF) leads to a redistribution of the proportion boride phases in the surface layers, changes the period of crystal lattice and increasing the diffusion coefficient.

In this paper we study the structure, phase composition, microhardness, crack resistance, wear resistance boride coatings obtained at complex saturation with boron and copper in the application of an external magnetic field (EMF). Investigations have shown that this method allows the application of boride coatings in 1.5 – 2 times decrease the duration saturation detail, and receive coating with high hardness, wear resistance, crack resistance.

It is established that the application EMF formed a continuous, homogeneous boride layer with thickness coatings in 2 times higher than boride coatings without EMF for the equal duration of the process. When imposing EMF in boride layers observed the redistribution quantitative relation boride phases, namely: decrease of volume phase FeB, and on diffractograms surface layers boride coatings obtained after boriding fixed presence phases FeB and Fe₂B. After complex saturation boron and copper in the application of external magnetic fields fixed phases FeB and Cu.

The researches have shown that the highest spalling stress value is reached in boride phases, obtained in powder environments with copper powder at the application of EMF, and respectively is 420 compared with 225 MPa for coating obtained without EMF. Increased shear stress values in complex layers obtained after saturation with boron and copper caused by the formation of phases more viscosity, for which crack K_1c in 1.4 – 2.0 times higher than the initial boride phases FeB and Fe₂B.

Application of EMF at boriding improves tribological characteristics of coatings: decreases coefficient of friction and increase in 1.5 – 2.5 times wear resistance.

The conditions are substantiated for the loss of thermodynamic stability of a tribosystem and for its adaptation with a decreasing wear rate at the moving frictional contact of parts from materials with an ultrafine-grained structure produced by equal-channel angular pressing. The regularities of the influence of the structure’s dispersion degree and the friction contact’s temperature on the tribotechnical characteristics of ultrafine-grained materials are established theoretically and experimentally.

The results of studies wear resistance of boron coatings alloyed with Сu, V, Nb, Cr or Ti under dry friction – slip in the air, and it was determined that the best coatings are the boride layers alloyed with copper. Alloying with copper inereases wear resistance of boride layers in 3 times. When alloying of boride layers with niobium wear resistance increases in 2,8 times, with titanium – in 2,4 times, with chromium and vanadium – in 1,5 times. Wear resistance of boride coatings alloyed with copper under dry friction – slip 14 times higher than wear resistance of bronze of Cu – Al – Mn system and wear resistance increases when applying boride layers alloyed with copper.

In this paper it was investigated the formation of complex boriding diffusion layers on metastable austenite Cr-Mn-N steel powder method. Defined phase and chemical composition, thickness, microhardness and wear resistance obtained by layers of metastable austenite Cr-Mn-N steel. It is established that the application of an external magnetic field (EMF) leads to a redistribution of the proportion boride phases in the surface layers of the crystal lattice period changes. EMF allows in 1.5 – 2 times to reduce the period of saturation details, microhardness diffusion boride coatings increase to 20,5 – 21 GPa and increase their wear resistance in 2.4 – 3 times compared to steel without protective coating. Boriding a magnetic field will increase the microhardness boride coatings 6 – 7 GPa compared to the boriding without application of a magnetic field.

The results of studies on the application of complex boron coating powder method on hard alloys. Defined phase and chemical composition, thickness and microhardness of the coating on alloys.

It was established that after diffusion saturation of hard alloy in boron mixture for 4 hours formed coating with boride phases TiB, WB, CoB and WC, TiC, whose thickness is 50-60 microns. At complex saturation with boron and copper for 4 hours diffusion saturation formed coating with boride phases TiB, WB, CoB and WC, TiC and separate inclusions of copper with a thickness of the diffusion layer up to 70-80 microns.

Boriding and complex saturation with boron and copper allows in 2 – 2.5 times increase the microhardness of the surface layers of hard alloys, that in turn leads to increased wear resistance.

The article deals with forming the adhesive bond of bodies at the crystal lattice level. There is offered a mathematical model for determining the adhesion wear. There are carried out laboratory tests for model validation. There is found that the amount of adhesive wear is nonline-arly dependent on the surface roughness inclination angle.

The results of studies wear resistance of boron coatings alloyed with Сu, V, Nb, Cr or Ti under dry friction – slip in the air, and it was determined that the best coatings are the boride layers alloyed with copper. Alloying with copper inereases wear resistance of boride layers in 3 times. When alloying of boride layers with niobium wear resistance increases in 2,8 times, with titanium – in 2,4 times, with chromium and vanadium – in 1,5 times. Wear resistance of boride coatings alloyed with copper under dry friction – slip 14 times higher than wear resistance of bronze of Cu – Al – Mn system and wear resistance increases when applying boride layers alloyed with copper.

This article discusses the braking system of a heavy-duty engine for the determination of the friction coefficient. The agricultural vehicle progresses at 40 km/h speed; its weight is 30,000 kg. While braking such a heavy vehicle, a significant amount of heat is released as a result of the disc brake’s friction. A significant part of the resulting heat is removed from the system using oil cooling. The cooling oil lubricates the various components and affects the frictional conditions significantly.

This article describes the construction of the braking system. It contains a description of the measurements on the test bench and the evaluation of the results. This study determines the frictional performance and describes the method for determining the friction coefficient of a given construction. The author shows the changes in the friction coefficient depending on the pressure and the temperature, and draws conclusions from the results.