2011 Volume 51 Issue 5 Pages 799-804
The present study evaluate the catalysis of Nd2O3 on the boriding of AISI 1045 steel using a 5% Nd2O3-containing boriding agent in a temperature range of 1213 K to 1350 K for 2 h–5 h. The morphology and types of borides formed on the steel surface were confirmed by optical microstructure, scanning electron microscopy and X-ray diffraction. The results show that the Nd2O3 has contrary effects on boriding process, i.e. promotion at high temperatures or hindrance at low temperatures. Nd2O3 addition can significantly reduce the activation energy of boride growth at high temperatures, decreased it from 198 kJ/mol to 137 kJ/mol, reduced by 31% in the high temperature range of 1133 K–1213 K as compared with that without Nd2O3 addition. The catalysis mechanism of RE element Nd during boriding process was discussed through the analysis of chemical reactions probably occurred in boriding agent, changes in surface morphology and chemical composition.