AN013 – Reduction of a steel at 1200°C-zh

INTRODUCTION

Thermogravimetry is a state of the art technique for studying gas / solid reactions, and have been thoroughly applied to metals and alloys oxidation under various conditions [1]. Oxidation /hydrogenation cycles can also be applied, but with more care taken to the safety related issues. TAG thermobalances are particularly well adapted when complex gas changes and temperature programs as it is equipped with a dual furnaces system, allowing a direct compensation of the so-called buoyancy effect.

Figure 1 – Sample mass change and temperature as a function of time during the hydrogenation

Figure 1 – Sample mass change and temperature as a function of time during the
hydrogenation

 

EXPERIMENTAL

Sample is a 304L stainless steel plate (L: 11 mm H: 30 mm) directly hung in the furnace of the TAG thermobalance. The sample is first oxidized at 500°C during several hours, then heated at 1000°C under a flow of hydrogen. Once the mass uptake (due to remaining trace of oxygen and water in the system) is stabilized, the temperature is quickly raised from 1000°C to 1200°C.

 

RESULTS AND CONCLUSIONS

Once stabilized at 1200°C, the steel sample mass decreases linearly during approximately 20 minutes and then slowly stabilizes to reach a new equilibrium after 4 hours. This mass loss is due to the reduction of the steel.

[1] D. Monceau and D. Poquillon, Oxidation of Metals, Vol. 61, Nos. 1/2, Feb. 2004