High density sintered ferrous alloys

Claim 2

A sintered high speed steel of at least 95% theoretical density consisting essentially of, in percentages by weight: ______________________________________ carbon 0.6-2.5% chromium 2-8% copper 4.5-20% molybdenum 0.5-10% phosphorus 0.4-1.2% tungsten 1-20% vanadium 1-5% cobalt 0-12% manganese 0-2% nickel 0-2% ______________________________________ the balance being iron and less than 2% by weight impurities, wherein the molybdenum, tungsten and vanadium contents are such that the % carbon content is in the range CCC%-0.1% to CCC%+0.3%, where CCC% is the calculated carbon content= (CWE/20)-0.4 and CWE=% tungsten content+twice % molybdenum content+six times % vanadium content, and wherein the phosphorus is derived from a copper phosphide containing 2 to 14% phosphorus.

Claim 3

An alloy as claimed in claim 1, consisting essentially of, in percentages by weight: ______________________________________ carbon 0.8-1.5% chromium 3-4% copper 8-15% molybdenum 3-5% phosphorus 6-0.8% tungsten 5-10% vanadium 2-4% cobalt 0.5-8.5% manganese 0.1-0.2% nickel 0.1-0.4% ______________________________________ the balance being iron and less than 2% by weight impurities.

Claim 4

An alloy as claimed in claim 1, wherein the density is at least 98% theoretical density.

Claim 5

An alloy as claimed in claim 1, wherein the copper phosphide contains 6 to 11% phosphorus.

Claim 6

An alloy as claimed in claim 4, wherein the copper phosphide contains 8% phosphorus.

Claim 7

A powder mixture comprising an atomized copper-free ferrous alloy powder and copper phosphide powder, which mixture when compressed and sintered provides a sintered ferrous alloy consisting essentially of, in percentages by weight: ______________________________________ carbon 0.6-2.5% chromium 2-8% copper 4.5-20% molybdenum 0.5-10% phosphorus 0.4-1.2% tungsten 1-20% vanadium 1-5% cobalt 0-12% manganese 0-2% nickel 0-2% ______________________________________ the balance being iron and less than 2% by weight impurities, wherein the molybdenum, tungsten and vanadium contents are such that the % carbon content is in the range CCC%-0.1% to CCC%+0.3%, where CCC% is the calculated carbon content= (CWE/20)-0.4 and CWE=%tungsten content+twice % molybdenum content+six times % vanadium content, and wherein the copper phosphide contains 2to 14% phosphorus.

Claim 8

A powder mixture comprising an atomized copper-free ferrous alloy powder and copper phosphide powder, which mixture when compressed and sintered provides a sintered ferrous alloy consisting essentially of, in percentages by weight: ______________________________________ carbon 0.6-2.5% chromium 2-8% copper 4.5-20% molybdenum 0.5-10% phosphorus 0.4-1.2% tungsten 1-20% vanadium 1-5% cobalt 0-12% manganese 0-2% nickel 0-2% ______________________________________ the balance being iron and less than 2% by weight impurities, wherein the molybdenum, tungsten and vanadium contents are such that the % carbon content is in the range CCC%-0.1% to CCC%+0.3%, where CCC% is the calculated carbon content= (CWE/20)-0.4 and CWE=%tungsten content+twice % molybdenum content+six times % vanadium content, and wherein the copper phosphide contains 2to 14% phosphorus.

Claim 9

A powder mixture as claimed in claim 6, which mixture when compressed and sintered provides a sintered ferrous alloy consisting essentially of, in percentages by weight: ______________________________________ carbon 0.8-1.5% chromium 3-4% copper 8-15% molybdenum 3-5% phosphorus 0.6-0.8% tungsten 5-10% vanadium 2-4% cobalt 0.5-8.5% manganese 0.1-0.2% nickel 0.1-0.4% ______________________________________ the balance being impurities.

Claim 10

A powder mixture as claimed in claim 7, wherein the copper phosphide contains 8 to 11% phosphorus.

Claim 11

A powder mixture as claimed in claim 8, wherein the copper phosphide contains 8% phosphorus.

Claim 12

A powder mixture as claimed in claim 6, wherein the ferrous alloy powder has been formed by water atomization of a molten copper-free ferrous alloy.

Claim 13

A process of manufacturing a sintered alloy article, which process comprises mixing atomized copper-free ferrous alloy powder and copper phosphide powder, compressing the powder mixture into a shaped article and sintering said article, wherein the powder mixture when compressed and sintered provides a sintered ferrous alloy consisting essentially of, in percentages by weight: ______________________________________ carbon 0.6-2.5% chromium 2-8% copper 4.5-20% molybdenum 0.5-10% phosphorus 0.4-1.2% tungsten 1-20% vanadium 1-5% cobalt 0-12% manganese 0-2% nickel 0-2% ______________________________________ the balance being iron and less than 2% by weight impurities, wherein the molybdenum, tungsten and vanadium contents are such that the % carbon is in the range CCC%-0.1% to CCC%+0.3%, where CCC% is the calculated carbon content=(CWE/20)-0.4 and CWE=% tungsten content+twice % molybdenum content+six times % vanadium content, and wherein the copper phosphide contains 2 to 14% phosphorus.

Claim 14

A process of manufacturing a sintered alloy article, which process comprises mixing atomized copper-free ferrous alloy powder and copper phosphide powder, compressing the powder mixture into a shaped article and sintering said article, wherein the powder mixture when compressed and sintered provides a sintered ferrous alloy consisting essentially of, in percentages by weight: ______________________________________ carbon 0.6-2.5% chromium 2-8% copper 4.5-20% molybdenum 0.5-10% phosphorus 0.4-1.2% tungsten 1-20% vanadium 1-5% cobalt 0-12% manganese 0-2% nickel 0-2% ______________________________________ the balance being iron and less than 2% by weight impurities, wherein the molybdenum, tungsten and vanadium contents are such that the % carbon is in the range CCC%-0.1% to CCC%+0.3%, where CCC% is the calculated carbon content=(CWE/20)-0.4 and CWE=% tungsten content+twice % molybdenum content+six times % vanadium content, and wherein the copper phosphide contains 2 to 14% phosphorus.

Claim 15

A process a claimed in claim 11, wherein the powder mixture when compressed and sintered provides a sintered ferrous alloy consisting essentially of, in percentages by weight: ______________________________________ carbon 0.8-1.5% chromium 3-4% copper 8-15% molybdenum 3-5% phosphorus 0.6-0.8% tungsten 5-10% vanadium 2-4% cobalt 0.5-8.5% manganese 0.1-0.2% nickel 0.1-0.4% ______________________________________ the balance being iron and less than 2% impurities.

Claim 16

A process as claimed in claim 11, wherein the copper phosphide contains 8 to 11% phosphorus.

Claim 17

A process as claimed in claim 11, wherein the copper phosphide contains 8% phosphorus.

Claim 18

A process as claimed in claim 11, wherein the sintered article is cooled at a rate which prevents hardening.

Claim 19

A process as claimed in claim 11, wherein the sintered article is heat-treated to increase its hardness and strength.

Claim 20

A process as claimed in claim 12, wherein the powder mixture is compressed to a compact of 65% to 80% theoretical density.

Claim 21

A powder mixture as claimed in claim 6, further including copper powder, copper alloy powder, graphite, or mixtures thereof.

Claim 22

A process as claimed in claim 11, wherein copper powder, copper alloy powder, graphite, or mixtures thereof is mixed with said ferrous alloy powder and copper phosphide powder prior to compressing the powder mixture.