Tungsten-carbide-based spray powder, and a substrate with a tungsten-carbide-based thermally sprayed layer
The invention relates to a thermal spray powder on a tungsten carbide basis, as well as to a method for the manufacture of such a spray powder for the thermal coating of a substrate, in particular for the thermal coating of a brake disc for a vehicle. In accordance with the invention, the spray powder includes, apart from impurities, WC in the range of 60% to 75% by weight, Cr 3 C 2 in the range of 14% to 22% by weight and Ni in the range of 11% to 23% by weight. The invention further relates to a sub-strate, in particular for a brake disc having a thermal spray layer on a tungsten carbide basis, as well as to a method for the manufacture of a thermal spray layer on a substrate.
1. A spray powder on a tungsten carbide basis for the thermal coating of a substrate, said spray powder, apart from impurities, comprising:
WC in the range of 60% to 75% by weight, Cr 3 C 2 in the range 14% to 22% by weight, Ni in the range of 11% to 23% by weight, and a maximum amount of Fe and of technically measurable impurities of 0.5% by weight,
wherein a standard particle size of a primary carbide of WC lies in the range of 0.5 μm to 2 μm.
2. A spray powder in accordance with claim 1 , wherein the portion of WC in the spray powder lies in the range of 63% to 70% by weight.
3. A spray powder in accordance with claim 1 , wherein the portion of Cr 3 C 2 in the spray powder lies in the range of 17% to 19% by weight.
4. A spray powder in accordance with claim 1 , wherein the portion of Ni in the spray powder lies in the range of 13% to 20% by weight.
5. A spray powder in accordance with claim 1 , wherein a nominal particle size of the spray powder lies in the range of 45 μm to +11 μm.
6. A spray powder in accordance with claim 1 , wherein the portion of WC in the spray powder is 67% by weight.
7. A spray powder in accordance with claim 1 , wherein the portion of Cr 3 C 2 in the spray powder is 18% by weight.
8. A spray powder in accordance with claim 1 , wherein the portion of Ni in the spray powder is 15% by weight.
9. A spray powder in accordance with claim 1 , wherein a nominal particle size of the spray powder lies in the range of -45 μm to +20 μm.
10. A method for the manufacture of a spray powder in accordance with claim 1 , comprising:
provision of WC, Cr 3 C 2 and Ni and manufacture of a powder mixture, which is composed of, apart from impurities, WC in the range of 60% to 75% by weight, Cr 3 C 2 in the range of 14% to 22% by weight, Ni in the range of 11% to 23% by weight, a maximum amount of Fe and of technically measurable impurities of 0.5% by weight and a standard particle size of a primary carbide of WC lies in the range of 0.5 μm to 2 μm.
manufacturing a suspension including the powder mixture, a solvent and an additive and homogenization of the suspension;
manufacturing a powder cake, in particular agglomerates, by spray drying of the suspension;
sintering the powder cake;
breaking and/or grinding the sintered powder cake to a powder material;
provision of the spray powder through selecting a predefined seed size distribution via a classification method.
11. A method in accordance with claim 10 , wherein the solvent is isohexane and the additive is a binder and/or an antifoaming agent.
12. A spray powder on a tungsten carbide basis for the thermal coating of a brake disc, said spray powder comprising a powder mixture having:
a nominal particle size larger than 11 μm and smaller than 45 μm;
a maximum amount of Fe and of technically measurable impurities of 0.5% by weight;
a composition of only WC in the range of 60% to 75% by weight, Cr 3 C 2 in the range of 14% to 22% by weight, and Ni in the range of 11% to 23% by weight; and
said powder mixture being made from a starting material comprising WC having a standard particle size in the range of 0.5 μm to 2 μm.