Poliakov I. Strengthening alloys with wear resistant coatings based on boride phases formed in the magnetic field

Dissertation is dedicated to the solution of scientific and technical problem of increasing the level of physical-mechanical and operational properties of steels and alloys surface by forming strengthened layers by diffusion boriding and complex boron and copper saturation in the magnetic field. New data about structural and phase changes in the diffusion boride layer obtained on steels and alloys under the action of external magnetic field (EMF) is obtained for the first time. It is shown that the imposition of EMF leads to a redistribution of boride phase proportion in the surface layers, changes of crystal lattice periods and the decrease of volume of elementary boride phase lattices. It is established that the use of EMF during boriding and complex boron and copper saturation, compared with traditional one, leads to the increase of boride layers thickness in 1.5-2 times for the same periods of diffusion saturation. It is shown that the formation of boride coating on carbon steels at boron saturation with simultaneous action of EMF leads to the increase of microhardness of boride layers formed on the carbon steels by 1.5-2 GPa (19-20 GPa), on the metastable austenite Cr-Mn-N steels by 4-5 GPa (19-19.5 GPa), and on the hard alloys by 2-3 GPa (30-31 GPa), that is associated with a decrease of coherent scattering regions; increase of crack resistance in 1.3 times (K1C = 2.2 MPa · m0,5) and tension of spallation in 1.4 times (345 MPa), as well as the decrease of coatings roughness characteristics - Ra in 1.3 and Rz in 1.2 times and as a consequence the increase of the operability of parts with boride coatings in 1.5-1.7 times.