Research on Properties and Growth Kinetics of Boride Layer of Fe-Based Powder Metallurgy Material Boriding Strengthened with Rare Earth

Abstract

The Fe-based powder metallurgy material was directly sintered and boriding with CeO₂ respectively by a pack powder boriding method to obtain a specimen with a boride layer. Boriding treatment was performed at 1123–1323 K for 3–10 h. The morphology and the thickness of the boride layer were observed with a ultra-depth-of-field microscope and a scanning electron microscope (SEM). The phase composition of the boride layer was analyzed by X-ray diffractometer. The quality of the bonding strength between the boride layer and the substrate was evaluated by the Rockwell-C adhesion test. The results showed that boriding with 2 wt% CeO₂ will inhibit the boriding treatment at low temperature and promote it at high temperature. Boriding with 4 wt% CeO₂ will inhibits the boriding process at both low and high temperature, and the inhibition becomes stronger as the temperature increases, the inhibiting effect at 1323 K is 9 times that at 1123 K. The quality of the bonding strength of the boride layer with CeO₂ is better than that specimen without CeO₂ and the quality of the bonding strength with 2 wt% CeO₂ is approved by the HF3 grade according to the specifications.

Keywords:

• Fe-based powder metallurgy
• pack boriding
• rare earths
• diffusion coefficient
• diffusion activation energy
• Rockwell-C adhesion test

Additional information

Funding

This study was supported by The Natural Science Foundation of Anhui Universities (KJ2021A1522 and KJ2020A1100), The fund of Anhui Quality Project ((2020dsgzs14).