Wear-resistant shaped magnetic article and process for making the same

Claim 2

A ferromagnetically soft wear-resistant shaped article made from metal powder in which a refractory oxide powder is substantially uniformly dispersed therein having a minimum particle size greater than about 1 micron which is large compared to the Block wall thickness in the composition of said article, the composition of said article consisting essentially of about ______________________________________ Weight Percent ______________________________________ Carbon <0.025 Manganese 0-2 Nickel 70-85 Chromium 0-5 Molybdenum 0-6 Copper 0-6 Titanium 0-1 Niobium 0-1 Refractory oxide 0.1-2.0 ______________________________________ the balance being essentially iron and incidental impurities with the iron content being greater than 10%, said article having a density at least 99% of theoretical with residual voids being larger than the Block wall thickness.

Claim 3

The article of claim 1 in which the refractory oxide is aluminum oxide and has a particle size greater than 1 micron up to about 50 microns but less than the smallest dimension of the article and products made therefrom.

Claim 4

The article of claim 2 having a composition containing about 0.7 to 1.20% aluminum oxide.

Claim 5

The article of claim 2 having a composition containing about 0.5% aluminum oxide.

Claim 6

The article of claim 2 having a composition containing no more than about 1.5% aluminum oxide.

Claim 7

The article of claim 2 formed with at least one air gap.

Claim 8

The article of claim 2 having a composition containing about 1% aluminum oxide.

Claim 9

The article of claim 2 having a composition containing about 78 to 82% nickel, about 4 to 5.25% molybdenum, about 0.1 to 2.0% aluminum oxide, and in which the balance consists essentially of iron and incidental impurities.

Claim 10

The article of claim 8 containing about 0.7 to 1.20% aluminum oxide.

Claim 11

The article of claim 8 containing about 0.5% aluminum oxide.

Claim 12

The article of claim 8 containing about 1.0% aluminum oxide.

Claim 13

The article of claim 8 containing no more than about 1.5% aluminum oxide.

Claim 14

The article of claim 2 having a composition containing about 75 to 80% nickel, 3 to 4.5% molybdenum, 1.5 to 3% chromium, about 0.1 to 2.0% aluminum oxide, and in which the balance consists essentially of iron and incidental impurities.

Claim 15

The article of claim 2 having a composition containing about 75 to 80% nickel, 3 to 5.5% copper, 1.5 to 3% chromium, about 0.1 to 2.0% aluminum oxide, and in which the balance consists essentially of iron and incidental impurities.

Claim 16

A process for making a ferromagnetically soft wear-resistant shaped article which includes the steps of blending metal powder and a refractory oxide powder having a minimum particle size greater than about 1 micron that is large compared to the Bloch wall thickness in the composition of said article to provide a substantially homogeneous mixture in such proportions that the composition of the article in its sintered and densified condition in weight percent consists essentially of about ______________________________________ Weight Percent ______________________________________ Carbon <0.025 Manganese 0-2 Nickel 70-85 Chromium 0-5 Molybdenum 0-6 Copper 0-6 Titanium 0-1 Niobium 0-1 Refractory oxide 0.1-2.0 ______________________________________ the balance being essentially iron and incidental impurities with the iron content being greater than 10%, then forming a preliminary shape from the blended powders, sintering the preliminary shape at a high enough temperature and for a long enough time in a reducing or inert atmosphere to provide a substantial amount of densification without reducing or melting the refractory oxide, and then working the sintered shape and reducing the thickness thereof to provide a shaped article having at least 99% theoretical density and in which the metal elements present except that combined to form refractory oxide are fully alloyed and homogeneously distributed.

Claim 17

A process for making a ferromagnetically soft wear-resistant shaped article which includes the steps of blending metal powder and a refractory oxide powder having a minimum particle size greater than about 1 micron that is large compared to the Bloch wall thickness in the composition of said article to provide a substantially homogeneous mixture in such proportions that the composition of the article in its sintered and densified condition in weight percent consists essentially of about ______________________________________ Weight Percent ______________________________________ Carbon <0.025 Manganese 0-2 Nickel 70-85 Chromium 0-5 Molybdenum 0-6 Copper 0-6 Titanium 0-1 Niobium 0-1 Refractory oxide 0.1-2.0 ______________________________________ the balance being essentially iron and incidental impurities with the iron content being greater than 10%, then forming a preliminary shape from the blended powders, sintering the preliminary shape at a high enough temperature and for a long enough time in a reducing or inert atmosphere to provide a substantial amount of densification without reducing or melting the refractory oxide, and then working the sintered shape and reducing the thickness thereof to provide a shaped article having at least 99% theoretical density and in which the metal elements present except that combined to form refractory oxide are fully alloyed and homogeneously distributed.

Claim 18

The process set forth in claim 15 in which the metal powders are elemental powders.

Claim 19

The process set forth in claim 16 in which sintering is carried out at a high enough temperature and long enough so that the elemental metals present are fully alloyed.

Claim 20

The process set forth in claim 17 in which the refractory oxide powder is aluminum oxide and has a particle size greater than 1 micron up to about 50 microns but less than the smallest dimension of said article and products and therefrom.

Claim 21

The process set forth in claim 18 in which the aluminum oxide particles range from 1 to about 25 microns.

Claim 22

The process set forth in claim 18 in which the preliminary shape is sintered at a temperature from 2150° F to just below the melting temperature of the elemental metal powders.

Claim 23

The process set forth in claim 20 in which sintering is carried out at a temperature above about 2200° F.

Claim 24

The process set forth in claim 20 in which sintering is carried out at a temperature up to about 2400° F.

Claim 25

The process set forth in claim 22 in which sintering is carried out at a temperature above about 2300° F.

Claim 26

The process as set forth in claim 20 in which residual voids present in the sintered preliminary shape are larger than the Bloch wall thickness.

Claim 27

The process as set forth in claim 20 in which said preliminary shape before sintering has a density less than about 80% of theoretical density, and the density following sintering and before working is greater than 90% of theoretical density.

Claim 28

The process as set forth in claim 25 in which hot working is carried out to a reduction in thickness of the sintered preliminary shape to at least 0.25 inch.

Claim 29

The process as set forth in claim 26 in which hot working is carried out to a reduction in thickness to at least about 0.1 inch.

Claim 30

The process as set forth in claim 27 in which reduction of the preliminary shape to the thickness of the article is completed by cold working.

Claim 31

The process as set forth in claim 25 in which a preliminary shape in its sintered condition having a thickness not greater than about 0.25 inch is cold worked to reduce its thickness to that of the shaped article with a density of at least 99% of theoretial.