Iron-based powder mixtures

Claim 2

An improved metallurgical powder composition comprising (a) an iron-based powder having an average particle size less than about 80 microns selected from the group consisting of iron powders and steel powders, (b) a minor amount of at least one alloying powder, and (c) about 0.005-1% by weight of a binding agent for said iron-based and alloying powders, said composition having been formed by mechanically mixing said iron-based powder and said alloying powder with said binding agent, wherein the improvement is characterized in that the binding agent is a resin substantially insoluble in water selected from the group consisting of (1) Homopolymers of vinyl acetate or copolymers of vinyl acetate in which at least 70% of the monomeric units are vinyl acetate; (2) Cellulosic ester or ether resins; (3) Methacrylate polymers or copolymers; (4) Alkyd resins; (5) Polyurethane resins; and (6) Polyester resins.

Claim 3

A composition of claim 1 in which the binding agent is a homopolymer or copolymer of vinyl acetate.

Claim 4

A composition of claim 2 in which the binding agent is polyvinyl acetate.

Claim 5

A composition of claim 2 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 6

A composition of claim 1 in which the binding agent is a cellulose resin selected from the group consisting of ethyl cellulose, cellulose acetate, cellulose acetate butyrate, and nitrocellulose.

Claim 7

A composition of claim 5 in which the binding agent is cellulose acetate butyrate.

Claim 8

A composition of claim 5 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 9

A composition of claim 1 in which the binding agent is a methacrylate resin selected from the group consisting of polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, methyl/butyl methacrylate copolymer, and methyl/ethyl methacrylate copolymer.

Claim 10

A composition of claim 8 in which the binding agent is n-butyl methacrylate homopolymer.

Claim 11

A composition of claim 8 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 12

A composition of claim 1 in which the binding agent is an alkyd resin.

Claim 13

A composition of claim 11 in which the alkyd resin is modified with a drying oil.

Claim 14

A composition of claim 11 in which the alkyd resin is modified with a polymerized ethylenically-unsaturated monomer.

Claim 15

A composition of claim 13 in which the alkyd resin is a pre-polymer of phthalic acid or phthalic anhydride and ethylene glycol, said pre-polymer modified with a vinyl-toluene polymer.

Claim 16

A composition of claim 11 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 17

A composition of claim 1 in which the binding agent is a polyurethane resin.

Claim 18

A composition of claim 16 in which the polyurethane resin is cured by exposure to ambient moisture.

Claim 19

A composition of claim 16 in which the polyurethane resin is cured from a prepolymer containing free isocyanate groups and a cross-linking agent selected from the group consisting of polyamines and monomeric polyols.

Claim 20

A composition of claim 16 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 21

A composition of claim 1 in which the binding agent is a polyester resin.

Claim 22

A composition of claim 20 in which the polyester resin is the reaction product of (a) the condensation product of an unsaturated dicarboxylic acid having 4-6 carbon atoms and a dihydroxy alcohol having 2-4 carbon atoms, and (b) an ethylenically unsaturated monomer.

Claim 23

A composition of claim 21 in which the condensation product is of maleic or fumaric acid and ethylene glycol, and in which the monomer is diallyl phthalate, vinyl toluene, styrene, or a methacrylate resin.

Claim 24

A composition of claim 21 in which the condensation product is of maleic acid and ethylene glycol, and in which the monomer is styrene.

Claim 25

A composition of claim 20 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 26

A composition of claim 1, 5, 8, 11, 16, or 21 in which the alloying powder has a mean particle size up to about 20 microns and in which the weight ratio of binding agent to alloying powder in the composition is dependent on the density of the alloying powder and is in accordance with the following schedule. ______________________________________ Density of Weight Ratio of Binding Alloying Powder Agent to Alloying Powder ______________________________________ ≦2.5 0.125 >2.5-4.5 0.100 >4.5-6.5 0.050 >6.5 0.025 ______________________________________

Claim 27

A composition of claim 11 in which the iron-based powder has an average particle size of about 70-80 microns.

Claim 28

A composition of claim 6 in which the alloying powder has an average particle size up to about 20 microns.

Claim 29

A composition of claim 4 in which the alloying powder has an average particle size up to about 20 microns.

Claim 30

A composition of claim 7 in which the alloying powder has an average particle size up to about 20 microns.

Claim 31

A composition of claim 10 in which the alloying powder has an average particle size up to about 20 microns.

Claim 32

A composition of claim 15 in which the alloying powder has an average particle size up to about 20 microns.

Claim 33

A composition of claim 19 in which the alloying powder has an average particle size up to about 20 microns.

Claim 34

A composition of claim 24 in which the alloying powder has an average particle size up to about 20 microns.

Claim 35

A composition of claim 25 in which the iron-bsed powder has an average particle size of about 70-80 microns.

Claim 36

An improved metallurgical powder composition comprising (a) an iron-based powder selected from the group consisting of iron powders and steel powders, (b) a minor amount of at least one alloying powder, and (c) about 0.005-1% by weight of a binding agent for said iron-based and alloying powders, said composition having been formed by mechanically mixing said iron-based powder and said alloying powder with said binding agent, wherein the improvement is characterized in that the binding agent is a resin substantially insoluble in water selected from the group consisting of (1) Homopolymers of vinyl acetate or copolymers of vinyl acetate in which at least 70% of the monomeric units are vinyl acetate; (2) Cellulosic ester or ether resins; (3) Methacrylate polymers or copolymers; (4) Alkyd resins; (5) Polyurethane resins; and (6) Polyester resins; and wherein the alloying powder has a mean particle size up to about 20 microns and the weight ratio of binding agent to alloying powder in the composition is dependent on the density of the alloying powder and is in accordance with the following schedule. ______________________________________ Density of Alloying Powder Weight Ratio of Binding (g/cc) Agent to Alloying Powder ______________________________________ ≦2.5 0.125 >2.5-4.5 0.100 >4.5-6.5 0.050 >6.5 0.025 ______________________________________

Claim 37

An improved metallurgical powder composition comprising (a) an iron-based powder selected from the group consisting of iron powders and steel powders, (b) a minor amount of at least one alloying powder, and (c) about 0.005-1% by weight of a binding agent for said iron-based and alloying powders, said composition having been formed by mechanically mixing said iron-based powder and said alloying powder with said binding agent, wherein the improvement is characterized in that the binding agent is a resin substantially insoluble in water selected from the group consisting of (1) Homopolymers of vinyl acetate or copolymers of vinyl acetate in which at least 70% of the monomeric units are vinyl acetate; (2) Cellulosic ester or ether resins; (3) Methacrylate polymers or copolymers; (4) Alkyd resins; (5) Polyurethane resins; and (6) Polyester resins; and wherein the alloying powder has a mean particle size up to about 20 microns and the weight ratio of binding agent to alloying powder in the composition is dependent on the density of the alloying powder and is in accordance with the following schedule. ______________________________________ Density of Alloying Powder Weight Ratio of Binding (g/cc) Agent to Alloying Powder ______________________________________ ≦2.5 0.125 >2.5-4.5 0.100 >4.5-6.5 0.050 >6.5 0.025 ______________________________________