2014-Sustainable Industrial Processing Summit
SIPS 2014 Volume 4: Recycling & Secondary Battery
| Editors: | Kongoli F |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2014 |
| Pages: | 498 pages |
| ISBN: | 978-1-987820-06-5 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Preparation of Nanocrystalline Hardmetal Powders from Tungsten-Containing Wastes
Archil Gachechiladze1; Vazha Garibashvili1; Aleksandre Kandelaki1; Omar Mikadze2; Archil Mikeladze1; Zurab Mirijanashvili1; George Tavadze1;1FERDINAND TAVADZE INSTITUTE OF METALLURGY AND MATERIALS SCIENCE, Tbilisi, Georgia; 2GEORGIAN TECHNICAL UNIVERSITY, Tbilisi, Georgia;
Type of Paper: Regular
Id Paper: 197
Topic: 5
Abstract:
The paper considers possibilities of utilizing tungsten-containing wastes for the production of hard metal powders. Efficiency of this study, from both - the scientific and commercial points of view, is beyond question: the proposed technology allows producing ultrafine powders with nanocrystalline structure; the technology is characterized by simplicity and production friendliness (high efficiency, low power inputs, etc.). Besides, cost for the charge (production waste, scrap) is much lower than that for the powders generally used for manufacturing of similar hard metals by applying conventional technologies.
Work accomplished is differentiated into two stages:
1. Possibilities of the charge procession by chloride technique have been studied and metal chlorides of the WCl4, NiFeCl4, CoCI2 type (intermediate product for preparing hard metals) were prepared. A device for chlorination was constructed.
2. A technique of producing hard metal powders was developed: first, molecular solution of chlorides (WCl4 and CoCI2) or (WCl4 and NiFeCl4) was prepared by dissolving chlorides in an organic compound - dimethylformamide (CH3)2NC(O)H, and heating to the temperature of 150-200°C. At this temperature, the organic solvent is decomposed resulting in a viscous fluid mass which consists of Roentgen amorphous components. Heating the mass to the temperature of 750 - 800°C in a reducing atmosphere initiates the processes of reduction and selective carbonization. As a result, there is obtained a powder, where each particle consists of tungsten carbide (WC) and a binding metal (NiFe or Co).
According to the results of X-ray analysis and mechanical testing, the obtained hard metal powders have nanocrystalline structure (< 100 nm) and improved mechanical properties.