TY - JOUR
T1 - Hydrogen reduction mechanisms of ilmenite between 823 and 1353 K
AU - Briggs, R. A.
AU - Sacco, A.
N1 - Funding Information:
Financial support and encouragement from the Advanced Projects Research Office and the In situ Resource Utilization Office at NASA-Johnson Space Center are gratefully acknowledged. Also, the assistance of Professor R. R. Biederman on the interpretation of electron micrographs and energy dispersive spectroscopic maps was helpful.
PY - 1991/3
Y1 - 1991/3
N2 - In situ gravimetric measurements and microscopic examinations were used to determine the mechanisms of oxygen removal from synthetic ilmenite disks between 823 and 1353 K. Under a hydrogen atmosphere, iron was observed to form a layer of low porosity on the surface of samples early in the reduction. This created diffusion limitations for hydrogen to the reaction front and for the escape of water vapor. A shrinking core reduction model, modified to include the growth of this iron film, was capable of predicting the conversion-time relationships of ilmenite samples. An activation energy of 43.2 ± 2.6 kcal/gmole was determined to be representative of reaction control over the temperature range 823–1023 K.
AB - In situ gravimetric measurements and microscopic examinations were used to determine the mechanisms of oxygen removal from synthetic ilmenite disks between 823 and 1353 K. Under a hydrogen atmosphere, iron was observed to form a layer of low porosity on the surface of samples early in the reduction. This created diffusion limitations for hydrogen to the reaction front and for the escape of water vapor. A shrinking core reduction model, modified to include the growth of this iron film, was capable of predicting the conversion-time relationships of ilmenite samples. An activation energy of 43.2 ± 2.6 kcal/gmole was determined to be representative of reaction control over the temperature range 823–1023 K.
UR - http://www.scopus.com/inward/record.url?scp=0026124046&partnerID=8YFLogxK
U2 - 10.1557/JMR.1991.0574
DO - 10.1557/JMR.1991.0574
M3 - Article
AN - SCOPUS:0026124046
SN - 0884-2914
VL - 6
SP - 574
EP - 584
JO - Journal of Materials Research
JF - Journal of Materials Research
IS - 3
ER -