The present work is concerned with the determination of boron activation energy in theC35 steel and an estimation of the mass gain generated by the boriding treatment. Theboride layers are produced by the pack-boriding method on the C35 steel in the temperaturerange of 800−1000 °C for atreatment time ranging from 0.5 to 8 h. The presence of both FeB and Fe2B phases was confirmed by theX-ray diffraction technique and by a microscopic examination of the cross-sections ofborided samples. The boron activation energy was evaluated as 153.1 kJ mol-1 in the temperature range of800−1000 °C. This value ofenergy is in agreement with the literature data. The mass gain was measured by weighingthe samples before and after the boriding treatment by the weighing technique. Theevolution of mass gain as a function of temperature and time can be described by aparabolic law. Finally, an iso-thickness diagram was established to be used as a tool tooptimize the boride layers thicknesses according to the industrial application.
