Investigation of diffusion kinetics of plasma paste borided AISI 8620 steel using a mixture of B 2 O 3 paste and B 4 C/SiC

摘要

In the present study, AISI 8620 steel was plasma paste borided by using various B 2 O 3 paste mixture. The plasma paste boriding process was carried out in a dc plasma system at temperatures of 973, 1023 and 1073 K for 2, 5 and 7 h in a gas mixture of 70% H 2 -30% Ar under a constant pressure of 10 mbar. The properties of the boride layer were evaluated by optical microscopy, X-ray diffraction, Vickers micro-hardness tester and the growth kinetics of the boride layers. X-ray diffraction analysis of boride layers on the surface of the steel revealed FeB and Fe 2 B phases. Depending on temperature and layer thickness, the activation energies of boron in steel were found to be 124.7 kJ/mol for 100% B 2 O 3 .