Abstract
In this study, the growth kinetics of the boride layers forming on low carbon steel substrates was investigated during electrochemical boriding which was performed at a constant current density of 200 mA/cm 2 in a borax based electrolyte at temperatures ranging from 1123 K to 1273 K for periods of 5-120 min. After boriding, the presence of both FeB and Fe 2 B phases were confirmed by the X-ray diffraction method. Cross-sectional microscopy revealed a very dense and thick morphology for both boride phases. Micro hardness testing of the borided steel samples showed a significant increase in the hardness of the borided surfaces (i.e., up to (1700 ± 200) HV), while the hardness of un-borided steel samples was approximately (200 ± 20) HV. Systematic studies over a wide range of boriding time and temperature confirmed that the rate of the boride layer formation is strongly dependent on boriding duration and has a parabolic character. The activation energy of boride layer growth for electrochemical boriding was determined as (172.75 ± 8.6) kJ/mol.
| Original language | English |
|---|---|
| Pages (from-to) | 6928-6934 |
| Number of pages | 7 |
| Journal | Applied Surface Science |
| Volume | 257 |
| Issue number | 15 |
| DOIs | |
| Publication status | Published - 15 May 2011 |
Funding
The authors would like to thank Prof. Dr. Suheyla Aydın for her helps on the processing of kinetic data. The XRD experiments were carried out in part in the Frederick Seitz Materials Research Laboratory Central Facilities, University of Illinois, which are partially supported by the U.S. Department of Energy under grants DE-FG02-07ER46453 and DE-FG02-07ER46471 .
| Funders | Funder number |
|---|---|
| U.S. Department of Energy | DE-FG02-07ER46453, DE-FG02-07ER46471 |
Keywords
- Activation energy
- Boride layer thickness
- Electrochemical boriding
- Growth kinetics