Nanokristal WO3 Tozunun H2 Atmosferindeki İndirgenme Davranışı

Bu çalışma, nanokristal WO3 tozunun H2 atmosferindeki pirometalurjik indirgenme davranışını incelemeyi amaçlamaktadır. WO3 indirgenme kinetiği, 800, 900 ve 1000 K'de 370 cm3/dk H2 gaz akışında çalışılmıştır. İndirgenme mertebesini tespit edebilmek için kütle ölçümleri ve X-Işınları Kırınımı (XRD) analizleri gerçekleştirilmiştir. Fraksiyonel dönüşüm değerleri, sıcaklık ve süre ile artmıştır. Deneysel sonuçlar, tam indirgenmenin 1000 K'de ~15 dk içinde gerçekleştiğini göstermiştir. Taramalı Elektron Mikroskobu (SEM) analizinden bu şartta elde edilen ürünün 100±30 nm ortalama partikül boyutuna sahip küresel nanoyapılı tungsten partiküllerinden oluştuğu anlaşılmıştır. Ayrıca, indirgeme işleminin aktivasyon enerjisi ~84 kJ/mol olarak tespit edilmiştir. İndirgenme işleminin kimyasal kinetikler tarafından kontrol edildiği anlaşılmıştır.Deneysel bulgular, başlangıç oksit tozu olarak nanokristal WO3kullanılması durumunda indirgenmenin daha kolay gerçekleştiğini ve indirgenme sonrası elde edilen metalik tungsten tozunun da nanoboyutta olduğunu göstermektedir.

Reduction Behavior of Nanocrystalline WO3 Powder in H2 Atmosphere

Thisworkpurposes to examinepyrometallurgical reduction behavior of nanocrystalline WO3 powder in a flowing H2 atmosphere. WO3 reduction kinetics was investigated at 800, 900 and 1000 K at H2 flow rate 370 cm3/min. Mass measurements and X-Ray Diffraction (XRD) analyses were performed to detect the extent of reduction. Fractional conversion values raised withtemperature and time. Experimental results revealed that full reduction was obtained at 1000 K within ~15 min. Scanning Electron Microscope (SEM) analysis on the sample prepared at this condition revealed spherical nanosized tungsten particles with mean particle sizes of 100±30 nm. In addition, activation energy of the reduction process was determined to be ~84 kJ/mole. It has been understood that the reduction process was controlled by chemical kinetics.Experimental findings demonstrate that if the nanocrystalline WO3 is used as the starting oxide powder, the reduction is easier and the metallic tungsten powder obtained after the reduction is also nanosized.

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