STRUCTURE AND PROPERTIES OF SURFACE LAYERS METALS ON THE BASIS OF HIGH SOLID BORIDE OBTAINED IN CONDITIONS OF AN EXTERNAL MAGNETIC FIELD
- 1 National Technical University of Ukraine "Kiev Polytechnic Institute", Kiev, Ukraine
- 2 The Frantsevich Institute for Problems of Materials Science of NAS of Ukraine, Kiev, Ukraine
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 K1c 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.