Prystash M. "Regularities of phase- and structure formation of Fe-Ti-C and Fe-Ti-C-B materials in conditions of spark-plasma sintering"

Thesis focuses on studying regularities of phase- and structure formation of Fe-Ti-C and Fe-Ti-C-B materials in conditions of spark-plasma sintering and on the creation of materials with improved physico-mechanical properties. It is experimentally found out in present work, that an increase of input power during sintering of powder mixture of Fe-Ti-C system from 1.3 kJ/s to 4 kJ/s by changing current harmonic composition allows intensification of processes of ion diffusion and transmission of liquid metal and increasing density of consolidated specimens from ~80 % to 98 %, hardness from ~20 HRC to ~50 HRC, decrease loss of mass during abrasive wear from 30 % of mass to 7 %, and for Fe-Ti-C-B system - increase density from 70 % to 98 %, hardness from ~20 % HRC to ~50 HRC and decrease loss of mass from 20 % of mass to 1.8 % of mass. Author have theoretically justified and experimentally determined that increase of heating rate from 10 oC/s to 20 oC/s allows decreasing time of compacts densification based on Ferrum from 60 s to 40 s and obtain mean grain size on the level of 10 µm in their structure, which leads to an increase of their hardness from 60 HRB to 85 HRB. Obtained regularities allowed experimental determination of the fact that SPS of Fe-Ti-C-B with input power of 4 kJ/s in the mode with heating rate of 20 oC/s, pressure of 60 MPa and isothermal holding of 1100 oC during 180 s allows obtaining MMC of Fe-Ti-C-B system with hardness of 60 HRC and wear resistance during abrasive wear 7 times higher than wear resistance of HSS M2 tungsten-containing steel due to increase of Ti2B and FeB borides content from 5 % to 10 %. Composite material of Fe-Ti-C-B, produced according to recommendations, issued in work, was used as plates for cutting polymer isolation and punches for titanium foil on the state enterprise "Experimental Production" of Institute of Pulse Processes and Technologies. According to tests results, durability of proposed material was on the level of HSS M2 instrumental steel, but due to the fact that cost of Fe-Ti-C-B system materials is lower, from economical point of view it allows significant increase of enterprise profit.