Composite cobalt - tungsten oxide powder is the main raw material for manufacturing cemented carbide powder, the finished product cemented carbide has been widely used in machinery manufacturing, oil exploration, military industry, aerospace and other fields because of its high hardness and density, wear-resisting and other special performance.
Common methods for manufacturing composite cobalt - tungsten oxide powder by using the ammonium metatungstate (AMT) or metatungstate as raw material are like following:
1. Make a certain concentration of ammonium metatungstate solution, then add a certain amount of cobalt carbonate powder (CoCO3) with heating, stirring for full reaction, and then cooling, filtering the compound salt solution; drying the compound salt solution to get the powder, get the compound powder heated in fluidized bed to finally get composite cobalt - tungsten oxide powder.
In this method, the reaction of AMT and cobalt carbonate is really slow and difficult to completely carry out; moreover, the cobalt content is difficult to get accurate control, also, it is limited by the inherent ratio of tungsten - cobalt in chemical reaction, which makes the cobalt content higher than 7% is difficult to get.
2. Get uniform tungsten - cobalt complex solution through the full reaction of a certain concentration of metatungstate and CoCO3; uniformly mix EDTA powder and CoCO3 powder and add it into the obtained tungsten - cobalt complex solution to carry out a reaction to get the cobalt compound solution with the required W:Co ratio; Then the solution is dried and granulated, carried out spray drying and calcination to get uniform component of composite cobalt - tungsten oxide powder.
In this method, the metatungstate is a kind of very unstable moderate acid and easy to precipitate yellow tungsten acid, thus to affect the actual recovery and accuracy for matching cobalt in composite cobalt - tungsten oxide powder.
3. Mix the ammonium metatungstate, cobalt salt (cobalt carbonate or cobalt oxide), EDTA powder uniformly according to the calculated ratio, then add the mixed powder into deionized water for rapid response to get cobalt - tungsten compound solution; then the solution is going through spray drying granulating, and removing water by drying and calcination to further get uniform composition, cobalt content can be adjusted, well controlled precision of composite cobalt - tungsten oxide powder.
This method composite cobalt - tungsten oxide powder with good uniformity, cobalt content during 7% ~ 30%, moreover, the cobalt content can be adjusted as your wish, and controlled accurately.
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