Cemented carbide tools
The present invention relates to a cemented carbide with a homogeneous and dense microstructure of hard constituents in a well distributed binder phase based on Co and/or Ni with a porosity of AOO-BOO according to ISO 4505. The cemented carbide has a nanoporosity of less than 2.5 pores/1000 μm 2 with a size of 0.5-1 μm. The cemented carbide is produced by using a binder phase powder with a specific surface area of 3 to 8 m 2 /g with a sponge shape and a grain size of the sponge shaped particles of between 1 and 5 μm.
1. Method of making a sintered body comprising one or more hard constituents and a binder phase based on cobalt and/or nickel by powder metallurgical methods including milling, pressing and sintering of powders,
wherein at least part of the binder phase powder includes particles having a specific surface area of 3 to 8 m 2 /g and a grain size of between 1 and 5 μm, and
wherein the sintered body has a homogeneous and dense microstructure of hard constituents distributed in the binder phase, a porosity of AOO-BOO according to ISO 4505, and a nanoporosity of less than 3 pores/1000 μm 2 after a heat treatment at 1370-1410° C. for about one hour in a protective atmosphere.
2. Method according to claim 1 wherein the at least part of the binder phase powder has a sponge shape.
3. Method according to claim 1 wherein the sintered body is a cemented carbide with a total content of binder phase of <8 wt %, <5 wt % of TiC+NbC+TaC and the remainder being WC with a grain size of <1 μm.
4. Method according to claim 3 wherein a total content of binder phase is 0.8-6 wt %.
5. Method according to claim 3 wherein a total content of binder phase is 1.5-4 wt %.
6. Method according to claim 3 wherein the sintered body has a WC grain size <0.8 μm.
7. Method according to claim 3 wherein the sintered body has a WC grain size <0.5 μm.
8. Method according to claim 1 wherein the binder phase powder consists of Co particles having a specific surface area of 3 to 8 m 2 /g, a grain size of between 1 and 5 μm, and a sponge shape.
9. Method according to claim 1 wherein the nanoporosity is less than 2.5 pores/1000 μm 2 .
10. Method according to claim 1 wherein the sintered body is a cemented carbide with a total content of binder phase of 1.5 to 2.9 wt %, <5 wt % of TiC+NbC+TaC and the remainder being WC with a grain size of <1 μm.
11. Method according to claim 1 wherein more than 25% of the binder phase powder has a specific surface area of 3 to 8 m 2 /g.