US4129443A — Method for improving the sinterability of iron po…

Claim 1

Independent Claim 169 words

A method of making sintered shapes from ferrous-based metallic particles containing maganese and silicon, the latter having been cryogenically comminuted, the steps comprising: (a) repeatedly impacting a charge of said metallic particles with a plurality of elements laden with copper or iron, each of said elements having a transverse dimension at least 50 times the longest dimension of any of said particles, said impacting being continued to simultaneously coat substantially each of said particles with a thin copper or iron envelope and to cold-work each of said particles having a size above 120-124 microns, (b) compacting a predetermined quantity of said impacted particles into a desired shape, and (c) heating said shape in an endothermic gas atmosphere to at least the sintering temperature for said metal particles to permit atomic diffusion to take place between particles in adjacent contact within said shape, said copper or iron envelope above each of said particles prohibiting oxidation of the ingredients of said particles during said heating, and said cold-working promoting increased diffusion.

Claim 2

Independent Claim 169 words

A method of making sintered shapes from ferrous-based metallic particles containing maganese and silicon, the latter having been cryogenically comminuted, the steps comprising: (a) repeatedly impacting a charge of said metallic particles with a plurality of elements laden with copper or iron, each of said elements having a transverse dimension at least 50 times the longest dimension of any of said particles, said impacting being continued to simultaneously coat substantially each of said particles with a thin copper or iron envelope and to cold-work each of said particles having a size above 120-124 microns, (b) compacting a predetermined quantity of said impacted particles into a desired shape, and (c) heating said shape in an endothermic gas atmosphere to at least the sintering temperature for said metal particles to permit atomic diffusion to take place between particles in adjacent contact within said shape, said copper or iron envelope above each of said particles prohibiting oxidation of the ingredients of said particles during said heating, and said cold-working promoting increased diffusion.

Claim 3

Dependent Claim 32 words

A method of making sintered shapes as in claim 1, in which said copper or iron laden elements comprise solid copper or iron spheres having a diameter of at least 0.1 inch.

Claim 4

Dependent Claim 72 words

The method of making a sintered shape as in claim 1, in which said charge of metallic particles is comprised of both coarse and fine particles, each of said particles having an irregular flake configuration prior to impaction, the fine particles constituting no more than 50% of said total particle volume, said fine particles being substantially devoid of cold-work after said impacting step while substantially each said coarse particles have cold-work strain.

Claim 5

Dependent Claim 57 words

The method of making sintered shapes as in claim 1, in which the metal particle charge is comprised of ferrous-based particles some of which contain manganese and/or silicon in solid solution above 0.1%, said thin copper or iron envelope about each of said particles operating to prevent oxidation of said manganese and silicon during said heating step.

Claim 6

Dependent Claim 67 words

A method of making sintered shapes as in claim 1, in which said impacting step is carried out with the use of a ball mill, the rate and frequency of contact between said metal particles and the elements of said ball mill being adjusted to achieve a rate of stress over a period of time to achieve said cold work in the particle sizes above 124 microns.

Claim 7

Dependent Claim 38 words

The method of making sintered shapes as in claim 1, in which said compaction step is carried out to produce a green density in said shape compact of at least 6.4 g./cc. by the use of 30 tsi.

Claim 8

Dependent Claim 49 words

The method of making sintered shapes as in claim 1, in which said shape has a first volume as a result of said compacting step and has a second volume as a result of said heating step, the difference between said first and second volumes being at least 10%.

Claim 9

Dependent Claim 69 words

A method of making sintered shapes as in claim 1, in which said charge of metal particles is comprised of randomly irregular ferrous particles each of which are non-spherical, said shape being heated to a sintering temperature of 2050° F. and held at said sintering temperature for a period of at least 20 minutes, whereby shrinkage between the cold compacted shape and said sintered shape is at least 7.0%.

Claim 10

Independent Claim 212 words

A method of making an intermediate powder, comprising: (a) selecting metallic turnings having oxidizable ingredients and which have a surface-to-volume ratio of at least 60:1, (b) simultaneously refrigerate to below the ductile-brittle transition temperature of said turnings and impacting said turnings with a fracturing force, continuing said refrigeration and impaction for a period of time to comminute said turnings, (c) impacting said comminuted particles at ambient temperature conditions with an abrading force, said impacting being carried out by the use of elements laden with a protective metal protective against oxidation of ingredients soluble in the base metal of said turnings and having a hardness less than that of the coated powder to promote transfer of said protective metal to said particles upon impact between said elements and particles, said protective metal having a melting temperature below but substantially near the liquidus of said particles and being completely soluble in said metal of said particles, said protective metal being relatively easy to abrade, and (d) continuing to carry out the impaction of step (c) to provide both coating of said particles with a thin envelope of said protective metal and cold working of substantially each particle having a size greater than 124 microns to thereby promote at least one cold-work strain site therein.

Claim 11

Independent Claim 212 words

A method of making an intermediate powder, comprising: (a) selecting metallic turnings having oxidizable ingredients and which have a surface-to-volume ratio of at least 60:1, (b) simultaneously refrigerate to below the ductile-brittle transition temperature of said turnings and impacting said turnings with a fracturing force, continuing said refrigeration and impaction for a period of time to comminute said turnings, (c) impacting said comminuted particles at ambient temperature conditions with an abrading force, said impacting being carried out by the use of elements laden with a protective metal protective against oxidation of ingredients soluble in the base metal of said turnings and having a hardness less than that of the coated powder to promote transfer of said protective metal to said particles upon impact between said elements and particles, said protective metal having a melting temperature below but substantially near the liquidus of said particles and being completely soluble in said metal of said particles, said protective metal being relatively easy to abrade, and (d) continuing to carry out the impaction of step (c) to provide both coating of said particles with a thin envelope of said protective metal and cold working of substantially each particle having a size greater than 124 microns to thereby promote at least one cold-work strain site therein.

Claim 12

Dependent Claim 46 words

The method of making an intermediate powder as in claim 9, in which the step of refrigeration is carried out by the use of liquid nitrogen, said impaction being carried out by the use of a ball mill having ball elements to impact with said particles.

Claim 13

Dependent Claim 25 words

The method of making an intermediate powder as in claim 10, in which said ball elements of said ball mill are comprised of solid copper.

Claim 14

Independent Claim 152 words

A method of making a powder compact, comprising: (a) selecting metallic machine turnings comprised substantially of ferrous-based material, said turnings having a surface-to-volume ratio of at least 60:1, (b) simultaneously refrigerating and impacting said turnings to promote comminution of said metal turnings to a powder, (c) repeatedly impacting a charge of said powder with a plurality of copper or iron laden elements having a transverse dimension at least 50 times the largest dimension of any particles of said powder, said impacting being carried out at ambient temperature conditions to simultaneously coat substantially each of said particles with a thin copper or iron shell and to stress substantially each of said particles above 124 microns to effect cold-working therein and to deliberately establish at least one non-natural defect site in each of said particles above 124 microns, and (d) compacting a predetermined quantity of said copper or non-coated particles into a desired shape.

Claim 15

Independent Claim 152 words

A method of making a powder compact, comprising: (a) selecting metallic machine turnings comprised substantially of ferrous-based material, said turnings having a surface-to-volume ratio of at least 60:1, (b) simultaneously refrigerating and impacting said turnings to promote comminution of said metal turnings to a powder, (c) repeatedly impacting a charge of said powder with a plurality of copper or iron laden elements having a transverse dimension at least 50 times the largest dimension of any particles of said powder, said impacting being carried out at ambient temperature conditions to simultaneously coat substantially each of said particles with a thin copper or iron shell and to stress substantially each of said particles above 124 microns to effect cold-working therein and to deliberately establish at least one non-natural defect site in each of said particles above 124 microns, and (d) compacting a predetermined quantity of said copper or non-coated particles into a desired shape.

Claim 16

Dependent Claim 80 words

The method of making a compact as in claim 12, in which said copper laden elements consist of solid copper or iron balls having a diameter substantially about 0.5 inches, said copper balls operating within a revolving housing of a ball mill, said housing being rotated so as to impact said copper or iron balls with said comminuted particles at a predetermined rate and stress frequency so as to produce said copper or iron coated particles and defect sites therein.

Claim 17

Independent Claim 178 words

A method of making sintered shapes from ferrous-based metallic particles containing oxidizable ingredients at conventional sintering temperatures and atmospheres, the latter having a substantially martensitic structure, the steps comprising: (a) repeatedly impacting a charge of said metallic particles with a plurality of elements laden with copper or iron, each of said elements having a transverse dimension at least 50 times the longest dimension of any of said particles, said impacting being continued to simultaneously coat substantially each of said particles with a thin copper or iron envelope and to cold-work each of said particles having a size above 120-124 microns, (b) compacting a predetermined quantity of said impacted particles into a desired shape, and (c) heating said shape to at least the sintering temperature for said metal particles in an atmosphere at least non-oxidizing to said envelope to permit atomic diffusion to take place between particles in adjacent contact within said shape, said copper or iron envelope about each of said particles during said heating, and said cold working promoting increased diffusion of the ingredients of said particles.

Claim 18

Independent Claim 178 words

A method of making sintered shapes from ferrous-based metallic particles containing oxidizable ingredients at conventional sintering temperatures and atmospheres, the latter having a substantially martensitic structure, the steps comprising: (a) repeatedly impacting a charge of said metallic particles with a plurality of elements laden with copper or iron, each of said elements having a transverse dimension at least 50 times the longest dimension of any of said particles, said impacting being continued to simultaneously coat substantially each of said particles with a thin copper or iron envelope and to cold-work each of said particles having a size above 120-124 microns, (b) compacting a predetermined quantity of said impacted particles into a desired shape, and (c) heating said shape to at least the sintering temperature for said metal particles in an atmosphere at least non-oxidizing to said envelope to permit atomic diffusion to take place between particles in adjacent contact within said shape, said copper or iron envelope about each of said particles during said heating, and said cold working promoting increased diffusion of the ingredients of said particles.

Claim 19

Dependent Claim 32 words

A method of making sintered shapes as in claim 14, in which said copper or iron laden elements comprise solid copper or iron spheres having a diameter of at least 0.1 in.

Claim 20

Dependent Claim 75 words

The method of making a sintered shape as in claim 14, in which said charge of metallic particles is comprised of both coarse and fine particles, each of said particles having an irregular chip configuration prior to impaction, the fine particles constituting no more than 50% of said total particle volume, said fine particles being substantially devoid of cold work after said impacting step while substantially each of said coarse particles have cold work strain.

Claim 21

Dependent Claim 64 words

The method of making sintered shapes as in claim 14, in which the metal particle charge is comprised of ferrous based particles some of which contain at least one of manganese, silicon, chromium or vanadium, in solid solution, said thin copper or iron envelope about each of said particles operating to prevent oxidation of said manganese, silicon, chromium or vanadium during said heating step.

Claim 22

Dependent Claim 67 words

A method of making sintered shapes as in claim 14, in which said impacting step is carried out with the use of a ball mill, the rate and frequency of contact between said metal particles and the elements of said ball mill being adjusted to achieve a rate of stress over a period of time to achieve said cold work in the particle sizes above 124 microns.

Claim 23

Dependent Claim 49 words

The method of making sintered shapes as in claim 14, in which said shape has a first volume as a result of said compacting step and has a second volume as a result of said heating step, the difference between said first and second volumes being at least 10%.

Claim 24

Dependent Claim 69 words

A method of making sintered shapes as in claim 14, in which said change of metal particles is comprised of randomly irregular ferrous particles each of which are non-spherical, said shape being heated to a sintering temperature of 2050° F. and held at said sintering temperature for a period of at least 20 minutes, whereby shrinkage between the cold compacted shape and said sintered shape is at least 7.0%.

Claim 25

Independent Claim 209 words

A method of making an intermediate powder, comprising: (a) selecting metallic turnings containing oxidizable ingredients during sintering at conventional temperatures and atmospheres which have a surface-to-volume ratio of at least 60:1, (b) heating said turnings to a temperature at which all carbon in said turnings dissolve, said heating being carried out under an atmosphere and for a period of time effective to provide substantially a complete martensitic solidification structure at a selected cooling rate, (c) cooling said turnings at said selected rate, (d) impacting said heat treated turnings at ambient temperature conditions with a fragmenting force, said impacting being carried out by the use of elements laden with a metal protective against oxidizing of said ingredients and having a hardness less than that of the coated powder to promote transfer to said particles upon impact between said elements and particles, said protective metal being completely soluble in said metal of said particles and being relatively easy to abrade, and (e) continuing to carry out the impaction of step (d) to provide both coating of said particles with a thin envelope of said protective metal and cold working of substantially each particle having a size greater than 124 microns to thereby promote at least one cold work strain site therein.

Claim 26

Independent Claim 209 words

A method of making an intermediate powder, comprising: (a) selecting metallic turnings containing oxidizable ingredients during sintering at conventional temperatures and atmospheres which have a surface-to-volume ratio of at least 60:1, (b) heating said turnings to a temperature at which all carbon in said turnings dissolve, said heating being carried out under an atmosphere and for a period of time effective to provide substantially a complete martensitic solidification structure at a selected cooling rate, (c) cooling said turnings at said selected rate, (d) impacting said heat treated turnings at ambient temperature conditions with a fragmenting force, said impacting being carried out by the use of elements laden with a metal protective against oxidizing of said ingredients and having a hardness less than that of the coated powder to promote transfer to said particles upon impact between said elements and particles, said protective metal being completely soluble in said metal of said particles and being relatively easy to abrade, and (e) continuing to carry out the impaction of step (d) to provide both coating of said particles with a thin envelope of said protective metal and cold working of substantially each particle having a size greater than 124 microns to thereby promote at least one cold work strain site therein.

Claim 27

Dependent Claim 50 words

The method of making an intermediate powder as in claim 21, in which the turnings are comprised of hypoeutectoid iron based metal having a carbon content less than 0.6%, and heating is carried out in a carburizing atmosphere to increase the carbon content of said turnings to at least 0.6%.

Claim 28

Dependent Claim 31 words

The method of making an intermediate powder as in claim 21, in which said impaction is carried out by a ball mill having ball elements comprised of solid copper or iron.

Claim 29

Dependent Claim 52 words

The method of making an intermediate powder as in claim 21, in which the carbon content of said untreated as well as treated turnings is between 0.09 and 0.6%, the cooling rate of step (b) being sufficiently rapid to quench said turnings and produce a solidification structure having at least 80% martensite.

Claim 30

Independent Claim 168 words

A method of making a powder compact, comprising: (a) selecting metallic machine turnings comprised substantially of ferrous based material, said turnings having a surface-to-volume ratio of at least 60:1 and a hypoeutectoid composition, (b) heat treat said turnings to provide a martensitic structure therein of at least 80%, (c) milling said heat treated turnings to provide chips of about -30 mesh, (d) repeatedly impacting a charge of said milled chips with a plurality of copper or iron laden elements having a transverse dimension at least 50 times the largest dimension of any chip, said impacting being carried out at ambient temperature conditions to simultaneously coat substantially each of said particles with a thin copper or iron shell and to stress substantially each of said particles above 124 microns to effect cold working therein and to deliberately establish at least one non-natural defect site in each of said particles above 124 microns, and (e) compacting a predetermined quantity of said copper or iron coated particles into a desired shape.

Claim 31

Independent Claim 168 words

A method of making a powder compact, comprising: (a) selecting metallic machine turnings comprised substantially of ferrous based material, said turnings having a surface-to-volume ratio of at least 60:1 and a hypoeutectoid composition, (b) heat treat said turnings to provide a martensitic structure therein of at least 80%, (c) milling said heat treated turnings to provide chips of about -30 mesh, (d) repeatedly impacting a charge of said milled chips with a plurality of copper or iron laden elements having a transverse dimension at least 50 times the largest dimension of any chip, said impacting being carried out at ambient temperature conditions to simultaneously coat substantially each of said particles with a thin copper or iron shell and to stress substantially each of said particles above 124 microns to effect cold working therein and to deliberately establish at least one non-natural defect site in each of said particles above 124 microns, and (e) compacting a predetermined quantity of said copper or iron coated particles into a desired shape.

Claim 32

Dependent Claim 80 words

The method of making a compact as in claim 25, in which said copper laden elements consist of solid copper or iron balls having a diameter substantially about 0.5 inches, said copper balls operating within a revolving housing of a ball mill, said housing being rotated so as to impact said copper or iron balls with said comminuted particles at a predetermined rate and stress frequency so as to produce said copper or iron coated particles and defect sites therein.

Claim 33

Dependent Claim 126 words

A continuous method of improving the sinterability and compactability of ferrous based scrap converted to powder, the improvement comprising the steps of: (a) circulating a charge of metallic scrap particles having a volume-to-surface ratio of at least 60:1 to form a circulating mass, (b) embrittling said particles either prior to or during said circulation, (c) either subsequent to or simultaneous with step (b), impacting said particles to fracture during one phase of said circulation and coating said fractured particles by impact-transfer with an oxidation protective metal having a melting temperature below but substantially near the liquidus of said particles and being completely soluble in the metal of said particles, said protective metal having a hardness less than the coated metal to provide for ease of abrasion.

Claim 34

Dependent Claim 126 words

A continuous method of improving the sinterability and compactability of ferrous based scrap converted to powder, the improvement comprising the steps of: (a) circulating a charge of metallic scrap particles having a volume-to-surface ratio of at least 60:1 to form a circulating mass, (b) embrittling said particles either prior to or during said circulation, (c) either subsequent to or simultaneous with step (b), impacting said particles to fracture during one phase of said circulation and coating said fractured particles by impact-transfer with an oxidation protective metal having a melting temperature below but substantially near the liquidus of said particles and being completely soluble in the metal of said particles, said protective metal having a hardness less than the coated metal to provide for ease of abrasion.

Claim 35

Dependent Claim 75 words

The method as in claim 27, in which, during said one phase of circulation said particles are reduced in temperature to below the ductile-brittle transition temperature to provide embrittlement, and during said another phase of circulation of said ferrous particles, the particles are allowed to rise in temperature above the ductile-brittle temperature condition, the particles are additionally impacted to impart a controlled degree of cold work to the surface of each of said fragmented particles.

Claim 36

Dependent Claim 192 words

A continuous method of making an intermediate ferrous powder having improved sinterability and compactability, the process comprising: (a) selecting metallic scrap particles in the form of turnings containing manganese and silicon, and which turnings have a surface-to-volume ratio of at least 60:1, (b) circulating said metallic scrap particles while cooling said particles below the ductile-brittle transition temperature in at least one zone of said circulation and allowing said particles to rise in temperature above the ductile-brittle transition temperature but below ambient temperature conditions in another zone, (c) impacting said particles by use of a fracturing force in said one zone of circulation to comminute said turnings and to impart a coating on said fractured pieces consisting of an oxidation protective metal having a melting temperature below but substantially near the liquidus of said pieces and being completely soluble in said metal of said pieces, said protective metal being abradable by said fracturing force, (d) impacting said comminuted particles in said other zone to effect a controlled degree of cold work of the surface of substantially each comminuted particle, and (e) separating said comminuted coated and cold worked particles from said circulating body.

Claim 37

Dependent Claim 192 words

A continuous method of making an intermediate ferrous powder having improved sinterability and compactability, the process comprising: (a) selecting metallic scrap particles in the form of turnings containing manganese and silicon, and which turnings have a surface-to-volume ratio of at least 60:1, (b) circulating said metallic scrap particles while cooling said particles below the ductile-brittle transition temperature in at least one zone of said circulation and allowing said particles to rise in temperature above the ductile-brittle transition temperature but below ambient temperature conditions in another zone, (c) impacting said particles by use of a fracturing force in said one zone of circulation to comminute said turnings and to impart a coating on said fractured pieces consisting of an oxidation protective metal having a melting temperature below but substantially near the liquidus of said pieces and being completely soluble in said metal of said pieces, said protective metal being abradable by said fracturing force, (d) impacting said comminuted particles in said other zone to effect a controlled degree of cold work of the surface of substantially each comminuted particle, and (e) separating said comminuted coated and cold worked particles from said circulating body.

Claim 38

Dependent Claim 50 words

The method as in claim 21, in which said impaction of step (c) is carried out by the use of cylindrical or spherical elements consisting essentially of said protective metal, said protective metal being of the type which is not brittle at temperatures at which said metallic particles are brittle.

Claim 39

Dependent Claim 21 words

The method as in claim 30, in which said impacting elements consist essentially of at least one of copper and iron.

Claim 40

Dependent Claim 61 words

The method as in claim 21, in which said impacting is carried out in a rotatable mill chamber containing cylindrical or spherical elements consisting essentially of copper or iron, said mill chamber being defined with a maximum control dimension extending across a central cross-section of said chamber, said elements having their smallest dimension no greater than 10% of said control dimension.

Claim 41

Dependent Claim 67 words

The method as in claim 30, in which said circulation is carried out continuously in an inclined cylinder undergoing movement to translate and agitate said particles through said cylinder, said particles are reduced in temperature to below said ductile-brittle transition temperature by the introduction of liquid nitrogen into the high end of said cylinder to form a slurry in combination with said metallic particles and impacting elements.

Claim 42

Dependent Claim 32 words

The method as in claim 33, in which said comminuted, coated and cold worked particles are separated from said slurry by the use of a sieve having a mesh size of -30.

Claim 43

Dependent Claim 28 words

The method as in claim 34, in which the openings provided by said sieve are shaped squarely whereby a graded particle distribution is provided in the separated particles.

Claim 44

Independent Claim 305 words

A method of making sintered shapes from metallic particles containing Mn and Si, the steps comprising: (a) selecting metallic scrap pieces having a surface-to-volume ratio of at least 60:1, (b) circulating said metallic pieces while cooling them to a temperature below the ductile-brittle transition temperature at one zone of said circulation and allowing said pieces to rise in temperature to above said ductile-brittle transition temperature in another zone of said circulation, (c) repeatedly impacting said circulating charge of metallic pieces with a plurality of elements in said circulation, each of said elements being laden with a metal which is not brittle at the high range of brittleness experienced by said metallic pieces, said elements being laden with an oxidation protective metal having a melting temperature below but substantially near the liquidus of said particles and being completely soluble in said metal of said particles, said protective metal being abradable by said metallic pieces, said elements having a transverse dimension of at least 50 times the shortest dimension of any of said particles, said impacting by said elements being carried out in said one zone to comminute said pieces by fracture and impart an oxidation protective metal envelope to each of said particles, said elements impacting said pieces in said other zone to impart a controlled degree of surface cold work to each of said particles, (d) compacting a predetermined quantity of said impacted comminuted particles into a desired shape, and (e) heating said shape to at least the sintering temperature for said metal particles to permit atomic diffusion to take place between said particles in adjacent contact within said shape, said protective metal envelope about each of said particles prohibiting oxidation of manganese and silicon in said particles during said heating and said cold work surface of each of said comminuted particles promoting increased diffusion.

Claim 45

Independent Claim 305 words

A method of making sintered shapes from metallic particles containing Mn and Si, the steps comprising: (a) selecting metallic scrap pieces having a surface-to-volume ratio of at least 60:1, (b) circulating said metallic pieces while cooling them to a temperature below the ductile-brittle transition temperature at one zone of said circulation and allowing said pieces to rise in temperature to above said ductile-brittle transition temperature in another zone of said circulation, (c) repeatedly impacting said circulating charge of metallic pieces with a plurality of elements in said circulation, each of said elements being laden with a metal which is not brittle at the high range of brittleness experienced by said metallic pieces, said elements being laden with an oxidation protective metal having a melting temperature below but substantially near the liquidus of said particles and being completely soluble in said metal of said particles, said protective metal being abradable by said metallic pieces, said elements having a transverse dimension of at least 50 times the shortest dimension of any of said particles, said impacting by said elements being carried out in said one zone to comminute said pieces by fracture and impart an oxidation protective metal envelope to each of said particles, said elements impacting said pieces in said other zone to impart a controlled degree of surface cold work to each of said particles, (d) compacting a predetermined quantity of said impacted comminuted particles into a desired shape, and (e) heating said shape to at least the sintering temperature for said metal particles to permit atomic diffusion to take place between said particles in adjacent contact within said shape, said protective metal envelope about each of said particles prohibiting oxidation of manganese and silicon in said particles during said heating and said cold work surface of each of said comminuted particles promoting increased diffusion.

Claim 46

Dependent Claim 36 words

The method as in claim 36, in which said cold work carried out in said other zone is effective to impart a defect site in substantially each of said particles having a size above 124 microns.

Claim 47

Dependent Claim 27 words

The method as in claim 36, in which said protective metal laden elements comprise solid copper or iron spheres having a diameter of at least 0.1 inch.

Claim 48

Dependent Claim 57 words

The method as in claim 36, in which the metal particles are comprised of ferrous based pieces, some of which contain at least one of manganese, silicon, chromium and vanadium in solid solution, said protective metal envelope about each of said particles operating to prevent oxidation of said manganese, silicon, chromium or vanadium during said heating step.

Claim 49

Dependent Claim 65 words

The method as in claim 36, in which said impacting step is carried out by the use of a ball mill and the frequency of contact between said impacting elements and said metal particles being adjusted to achieve a rate of stress over a period of time to provide at least one defect site in the particle sizes above 124 microns in said other zone.

Claim 50

Dependent Claim 27 words

The method as in claim 36, in which said ferrous pieces are comprised of machine turnings derived from conventional melted metals having high contents of oxidizable ingredients.

Claim 51

Dependent Claim 66 words

A method as in claim 36, in which said charge of metallic particles is comprised of randomly irregular ferrous particles each of which are nonspherical, said shape being heated to a sintering temperature of about 2050° F. and held at said sintering temperature for a period of at least 20 minutes, whereby shrinkage between the cold compacted shape and said sintered shape is at least 7.0%.

Claim 52

Dependent Claim 19 words

The method as in claim 14 in which said impacted particles are decreased in carbon content prior to compaction.

Claim 53

Dependent Claim 44 words

The method of making sintered shapes as in claim 17 in which said impacted particles are decarburized to a carbon level facilitating better compaction in step (c), said compaction being carried out to promote a density in said shape of at least 6.4 g./cc.

Claim 54

Dependent Claim 25 words

The method as in claim 14, in which said impacted particles are coated with copper, said impacted particles being decarburized prior to said coating treatment.

Claim 55

Dependent Claim 27 words

The method as in claim 14, in which said impacted particles are coated with iron, said impacted particles being decarburized subsequent to coating but prior to compaction.

Claim 56

Dependent Claim 41 words

The method as in claim 1, in which said elements impact said metallic particles causing a local cleansing of the metallic particle surface at the area of impact while simultaneously transferring some of the copper or iron material constituting said elements.

Claim 57

Independent Claim 195 words

A method of making sintered shapes from iron based metallic particles containing oxidizable ingredients, the latter having been cryogenically comminuted, the steps comprising: (a) repeatedly impacting a charge of said metallic particles with two groups of elements, one group being laden with copper with the elements of said one group being a powder having a transverse dimension no greater than 0.1 inch, the other group having hard elements devoid of copper and having a transverse dimension greater than 0.1 inch, said impacting being continued to simultaneously coat substantially each of said particles with a thin copper envelope and to stress said particles to provide at least one defect site in substantially each of said particles having a size above 120-124 microns, (b) compacting a predetermined quantity of said impacted particles into a desired shape, and (c) heating said shape to a sintering temperature for said metal particles in an atmosphere non-oxidizing to said envelope to permit atomic diffusion to take place between particles in adjacent contact within said shape, said copper envelope about each of said particles prohibiting oxidation of the ingredients of said particles during said heating, and said defect sites promoting increased diffusion.

Claim 58

Independent Claim 195 words

A method of making sintered shapes from iron based metallic particles containing oxidizable ingredients, the latter having been cryogenically comminuted, the steps comprising: (a) repeatedly impacting a charge of said metallic particles with two groups of elements, one group being laden with copper with the elements of said one group being a powder having a transverse dimension no greater than 0.1 inch, the other group having hard elements devoid of copper and having a transverse dimension greater than 0.1 inch, said impacting being continued to simultaneously coat substantially each of said particles with a thin copper envelope and to stress said particles to provide at least one defect site in substantially each of said particles having a size above 120-124 microns, (b) compacting a predetermined quantity of said impacted particles into a desired shape, and (c) heating said shape to a sintering temperature for said metal particles in an atmosphere non-oxidizing to said envelope to permit atomic diffusion to take place between particles in adjacent contact within said shape, said copper envelope about each of said particles prohibiting oxidation of the ingredients of said particles during said heating, and said defect sites promoting increased diffusion.

Claim 59

Dependent Claim 28 words

A method of making sintered shapes as in claim 48 in which said one group of elements comprise a copper powder and the second group comprise iron spheres.

Claim 60

Dependent Claim 29 words

A method of making sintered shapes as in claim 48 in which said particles and two groups of elements are directed along intersecting streams to promote said repeated impaction.

Claim 61

Dependent Claim 85 words

The method of making a sintered shape as in claim 48 in which said charge of metallic particles is comprised of both coarse and fine particles, each of said particles having an irregular flake configuration prior to impaction, the fine particles constituting no more than 50% of said total particle volume, most of said fine particles being substantially devoid of defect sites caused by cold work after said impacting step while most of said coarse particles each have at least one defect site after impacting.

Claim 62

Dependent Claim 54 words

The method of making sintered shapes as in claim 48 in which the metal particle charge is comprised of ferrous based particles some of which contain manganese and/or silicon in solid solution, said thin copper envelope about each of said particles operating to prevent oxidation of said manganese and silicon during said heating step.

Claim 63

Dependent Claim 70 words

A method of making sintered shapes as in claim 48 in which said impacting step is carried out with the use of a ball mill, the rate and frequency of contact between said metal particles and the elements of said ball mill being adjusted to achieve a rate of stress over a period of time to achieve said at least one defect site in the particle sizes above 124 microns.

Claim 64

Dependent Claim 38 words

The method of making sintered shapes as in claim 48 in which said compaction step is carried out to produce a green density in said shape compact of at least 6.4 g./cc. by the use of 30 tsi.

Claim 65

Dependent Claim 49 words

The method of making sintered shapes as in claim 48 in which said shape has a first volume as a result of said compacting step and has a second volume as a result of said heating step, the difference between said first and second volumes being at least 10%.

Claim 66

Dependent Claim 69 words

A method of making sintered shapes as in claim 48 in which said charge of metal particles is comprised of randomly irregular ferrous particles each of which are non-spherical, said shape being heated to a sintering temperature of 2050° F. and held at said sintering temperature for a period of at least 20 minutes, whereby shrinkage between the cold compacted shape and said sintered shape is at least 7.0%.

Claim 67

Independent Claim 168 words

A method of making a powder compact, comprising: (a) selecting metallic machine turnings comprised substantially of ferrous based material having oxidizable ingredients, said turnings having a surface-to-volume ratio of at least 33:1, (b) simultaneously refrigerating and impacting said turnings to promote comminution of said metal turnings to a powder, (c) repeatedly impacting a charge of said powder with two groups of elements, one group being laden with copper and each element thereof having a transverse dimension no greater than 0.1 inch, the other group having hard elements devoid of copper and having a transverse dimension greater than 0.1 inch, said impacting being carried out at ambient temperature conditions to simultaneously coat substantially each of said particles with a thin copper shell and to stress substantially each of said particles above 124 microns to effect cold working therein and to establish at least one defect site in each of said particles above 124 microns, and (d) compacting a predetermined quantity of said copper coated particles into a desired shape.

Claim 68

Independent Claim 168 words

A method of making a powder compact, comprising: (a) selecting metallic machine turnings comprised substantially of ferrous based material having oxidizable ingredients, said turnings having a surface-to-volume ratio of at least 33:1, (b) simultaneously refrigerating and impacting said turnings to promote comminution of said metal turnings to a powder, (c) repeatedly impacting a charge of said powder with two groups of elements, one group being laden with copper and each element thereof having a transverse dimension no greater than 0.1 inch, the other group having hard elements devoid of copper and having a transverse dimension greater than 0.1 inch, said impacting being carried out at ambient temperature conditions to simultaneously coat substantially each of said particles with a thin copper shell and to stress substantially each of said particles above 124 microns to effect cold working therein and to establish at least one defect site in each of said particles above 124 microns, and (d) compacting a predetermined quantity of said copper coated particles into a desired shape.

Claim 69

Dependent Claim 92 words

The method of making a compact as in claim 57 in which said first group of elements consist of copper powder and the second group of elements consist of iron balls having a diameter substantially about 0.5 inches, said copper powder, comminuted powder and iron balls operating within a revolving housing of a ball mill, said housing being rotated so as to impact said copper powder and iron balls with said comminuted particles at a predetermined rate and stress frequency so as to produce said copper coated particles and defect sites therein.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1981-12-11	1982-06-12	1982-12-12	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1985-12-11	1986-06-12	1986-12-12	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1989-12-11	1990-06-12	1990-12-12	$7700.00	Window Closed / Lapsed

Method for improving the sinterability of iron powder derived from comminuted scrap metal

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