MATHEMATICAL MODEL OF ELECTROSPARK FORMATION OF WEAR-RESISTANT COATINGS ON PROCESSED SURFACES

The article considers a new direction in optimizing the process of plasma hardening of the surfaces of cutting elements of agricultural machines based on the use of electric spark discharge energy. (Research purpose) The research purpose is in optimizing the technological process of hardening the surfaces of cutting elements of agricultural machines by the method of electric spark alloying of carbide material elements. (Materials and methods) A device under RF patent No. 2655420, developed by the scientific supervisor of the subject S. N. Sharifullin, was used for electric spark alloying. A tungsten-cobalt rod with a diameter of 4 millimeters, consisting of 94 percent tungsten and 6 percent cobalt, was used as the electrode material for this case. The processed sample of 65G steel, which is the main material of the working bodies of tillage equipment. The physical and chemical properties of the samples were studied with a scanning electron microscope EVO 50 XVP from Zeiss. (Results and discussion) After the electric spark treatment of the alloyed elements, there were about ten, while their spectra also appear at different irradiation energies. The alloyed elements in the surface layer are not only separate, but also in the form of compounds with other elements. Such alloying elements as carbon, cobalt and tungsten appeared in a noticeable amount in the surface layer. Electric spark treatment allows increasing the microhardness of the surfaces of cutting elements of tillage equipment up to three times. (Conclusions) When developing a mathematical model of the electric spark formation of wear-resistant coatings on the treated surfaces, it is necessary to use the energy conservation equations of the electron gas, the Maxwell equations, the continuity and momentum equations. The complex solution of these equations makes it possible to obtain the required output parameters depending on the input ones.

Characterization of Ferromagnetic Nanoparticles Produced by A Carbon Arc

ABSTRACTThe effect of increasing metal fraction on carbon arc nanoparticle production is examined for 10–50 weight percent cobalt starting materials. With 500 Torr of helium buffer gas, the carbon arc process yields carbon-coated FCC Co nanoparticles of similar sizes throughout this range. The saturation magnetization is believed to scale linearly with the relative abundance of Co. The variation in the coercivity with abundance is small compared to the dramatic changes which can arise from changes in the size of fine particles. The approach to magnetic saturation is more rapid in high abundance samples. This is attributed to interparticle interactions which align the easy axes when the nanoparticles crystallize within interconnected carbon shells. The switching field distribution as a function of Co abundance arises from both rotational barriers and from barriers due to the particle size distribution.

Tool Fracture Probability Under Steady State Cutting Conditions

Tool fracture probability for 6 weight percent cobalt tungsten carbide tools turning AISI 4340 steel (HB = 235 kg/mm2) at 200 fpm was found to be small at the beginning of a cut or during steady state cutting at feeds up to 0.100 ipr (2.54 mm/rev). Steady state fracture probability was found to be high only when cutting with severe chatter at feeds of 0.100 ipr (2.54 mm/rev) or higher. Tool fracture probabilities were determined by finite element analysis for elastic tool stresses, an intensified maximum tensile stress fracture criterion associated with circular defects [9] and Weibull plot giving percent failed versus fracture stress in uniaxial compression.