Effect of Milling and Heat Treatment on the Microstructure of 38wt%TiO2-36wt%NiO-26wt%C and the Influence of Produced Nanostructured Powder Mixtures on the Hydrogen Desorption from MgH2

In this study 38wt%TiO2-36wt%NiO-26wt%C powder mixture was ball milled for 5, 10, and 20 hours and then heat treated at 300, 600, 900 and 1200 oC for one hour. Results showed that chemical reaction between initial components of powder did not occur during milling. Increasing milling time from 5 to 20h and heat treatment temperature from 300 to 900oC led to reduction of NiO to Ni by graphite and transformation of anatase to rutile. Heat treatment at 1200oC led to appearance of NiTiO3 phase. In the next step 10 wt% of 20h milled samples which heat treated at various temperatures were added to MgH2 as catalyst and then ball milled for 20 hours. The effect of this process on the hydrogen desorption from MgH2 was investigated. Results showed that adding catalyst produced at 1200oC to MgH2 and ball milling for 20 hours led to 6.45wt% hydrogen desorption and 170oC decrease in desorption temperature. The reason of this improvement in hydrogen desorption properties was related to the catalytic effect of NiTiO3 phase.