Method of making a cemented carbide or cermet body
The present invention relates to a method of making a cemented carbide or a cermet body comprising the steps of first forming a powder blend comprising powders forming hard constituents and metal binder. The powder blend is then subjected to a mixing operation using a non-contact mixer wherein acoustic waves achieving resonance conditions to form a mixed powder blend and then subjecting said mixed powder blend to a pressing and sintering operation. The method makes it possible to maintain the grain size, the grain size distribution and the morphology of the WC grains.
1. A method of making a cemented carbide or a cermet body comprising the steps of:
forming a powder blend comprising powders forming hard constituents and metal binder;
subjecting said powder blend to a mixing operation using a non-contact mixer, wherein acoustic waves achieving resonance conditions are used to form a mixed powder blend, the acoustic waves having a frequency between 20-80 Hz; and
subjecting said mixed powder blend to a forming and a sintering operation.
2. The method according to claim 1 , wherein an organic binder is added to the powder blend.
3. The method according to claim 1 , wherein a mixing liquid is added to the powder blend to form a slurry prior to the mixing operation.
4. The method according to claim 3 , wherein the slurry is subjected to a drying step performed by spray drying.
5. The method according to claim 1 , wherein the powders include one or more hard constituents selected from borides, carbides, nitrides or carbonitrides of metals from groups 4, 5 and 6 of the periodic table.
6. The method according to claim 1 , wherein the binder metal powder is is selected from a group of one single binder metal, a powder blend of two or more metals, or a powder of an alloy of two or more metals, wherein the binder metals are selected from Cr, Mo, Fe, Co or Ni.
7. The method according to claim 1 , wherein the sintering is done by gas pressure sintering at a sintering temperature of between 1350 to 1500° C.
8. The method according to claim 1 , wherein the sintering is done by vacuum sintering at a sintering temperature between 1350 to 1500° C.
9. The method according to claim 1 , wherein a WC-Co based cemented carbide body is made.
10. The method according to claim 9 , wherein the WC-Co based cemented carbide body is made from WC raw material of a single crystal with WC grains, the WC grains after sintering having a spherical or an angular morphology.
11. The method according to claim 9 , wherein the WC grains after sintering have a spherical morphology and a Riley ratio of below 1.5.
12. The method according to claim 10 , wherein the WC grains after sintering have an angular morphology with a Riley ratio above 1.5.
13. The method according to claim 1 , wherein a cermet body is made.
14. The method according to claim 1 , wherein a cemented carbide is made.
15. The method according to claim 1 , wherein the frequency is between 50-70 Hz.