Infiltrated ferrous materials
Metallic alloys and methods for the preparation of free-standing metallic materials in a layerwise manner. The resulting layerwise construction provides a metallic skeleton of selected porosity which may be infiltrated with a second metal to provide a free-standing material that has a volume loss of less than or equal to 130 mm 3 as measured according to ASTM G65-04 (2010).
1. A method for layer-by-layer formation of a free-standing metallic part comprising:
(a) forming an article comprising at least a first layer and a second layer on the first layer, wherein:
the first and second layers each comprise metallic alloy particles and a binder;
the metallic alloy particles comprise, in weight percent: 17.0<Cr<22.0, 8.0<Mo<12.0, 2.0<B<5.0, 3.0<W<7.0, 0.5<C<2.0, 1.0<Mn<4.0, 1.0<Si<3.0, balance Fe; and
forming the article comprises:
forming the first layer via a binder jetting process; and
forming the second layer on the first layer via a binder jetting process;
(b) heating the article to produce a cured article having a porosity ranging from 20 to 60%, wherein the heating cures the binder;
(c) sintering the cured article, wherein the sintering comprises heating the cured article to remove the binder and cooling at a rate of less than 5° C./minute to form a porous metallic skeleton; and
(d) infiltrating the porous metallic skeleton with an infiltrant to form the free-standing metallic part, wherein the free-standing metallic part has a wear resistance with a volume loss of less than or equal to 130 mm 3 as measured according to ASTM 065-04(2010) Procedure A.
2. The method of claim 1 wherein the metallic alloy particles have a particle size distribution in the range of 0.005-0.300 mm.
3. The method of claim 1 wherein the first and second layers each have a thickness in the range of 0.010 to 0.300 mm.
4. The method of claim 1 wherein the porous metallic skeleton has a porosity in a range of 15% to 59.1%.
5. The method of claim 1 wherein the infiltrating of the porous metallic skeleton is configured to provide a final volume ratio of infiltrant to skeleton in the range of 15/85 to 60/40.
6. The method of claim 1 wherein the infiltrant is a metal alloy.
7. The method of claim 1 wherein the wear resistance of the free-standing part has a volume loss of 30 mm3 to 130 mm 3 as measured by ASTM 065-04(2010) Procedure A.
8. The method of claim 1 , wherein the cooling is at a rate of less than 2° C./minute.
9. The method of claim 1 , wherein during steps (c) and (d) nano-scale structures in the metallic alloy particles transform to create a uniform equiaxed structure.
10. The method of claim 1 wherein the metallic alloy particles consist of the following alloy composition, plus inevitable impurities, in weight percent:
a) 17.0<Cr<22.0, 8.0<Mo<12.0, 2.0<B<5.0, 3.0<W<7.0, 0.5<C<2.0, 1.0<Mn<4.0, 1.0<Si<3.0, balance Fe.
11. The method of claim 6 wherein the metal alloy is a copper (Cu) alloy.
12. The method of claim 11 wherein the metal alloy is bronze.
13. The method of claim 12 wherein the metal alloy is greater than 70 wt. % Cu.
14. The method of claim 12 wherein the metal alloy is 90 wt % Cu and 10 wt % Sn.