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The Preparation of Raw Nanometer Tungsten Carbide Powder |
| Author : Date : 2011-10-29 20:32:59 |
The Preparation of Raw Nanometer Tungsten Carbide Powder
At present ,there are a lot of ways to get nanometer tungsten carbide powder such as spraying, mechanical alloying, air-phase reaction, liquid-phase reaction,high-frequecny plasma synthesis,situ-carburization reduction and coprecipitation etc .
The Spraying conversion process was developed by Rutgers University in America ,with which the WC/Co powder get fused under molecular level, resulting in production of tungsten carbide products with WC grains size under 50nm.There are three steps for this process, which are preparation and combination for tungsten and cobalt salt solution;getting super fine tungsten and cobalt-salt powder after spray-drying process;to get nanometer WC/Co powder by reduction and carburization process of the WC and Co powder in the flowing reactor . However ,this process is only in the lab-step and unavailable to be commonly used for mass production.
On the other hand ,the mechanical alloying process is comparatively simple, which is to mechanical blending of elements with a proper proportion,and then make them under protective atmosphere to be long-run milled in high-energy ball milling equipment ,and get dispersed ultra fine powder after repeatedly extrusion,cold-welding and grinding processes ,finally achieve alloying in solid status .However ,in the mechanical alloying process ,the impurities are taken into the powders easily ,and cause great internal stress due to repeated squeeze them ,which definitely affect the powders pressing and sintering properties .
Air-phase reactionis the metal and active gas reacting chemically in a certain temperature ,forming metallic compound ,and then getting nano-compound powder by means of condensation.
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