Iron based powder

Patent metadata

Field	Value
Publication number	US-2021046543-A1
Application number	US-201716087377-A
Country	US
Kind code	A1
Filing date	Mar 15, 2017
Priority date	Mar 23, 2016
Publication date	Feb 18, 2021
Grant date	—

Abstract

Disclosed is a new diffusion-bonded powder consisting of an iron powder having 1-5%, preferably 1.5-4% and most preferabiy 1.5-3.5% by weight of copper particles diffusion bonded to the surfaces of the iron powder particles. The new diffusion bonded powder is suitable for producing components having high sintered density and minimum variation in copper content.

First claim

1 . An iron based powder consisting of particles of reduced copper oxide diffusion bonded to the surface of an atomized iron powder, wherein the content of copper is 1-5%-by weight of the iron based powder.

2 . The iron based powder according to claim 1 , wherein the maximum particle size is 250 μm, at least 75% is below 150 μm and at most 30% is below 45 μm, the apparent density is at least 2.70 g/cm3 and the oxygen content is at most 0.16% by weight and other compounds at most 1% by weight.

3 . The iron based powder according to claim 2 having a SSF-factor of at most 2.0, wherein the SSF-factor is defined as the quotation between the Cu content in weight % in the fraction of the iron based powder which passes a 45 μm sieve and the Cu content in weight % in the fraction of the iron based powder which does not pass a 45 μm sieve.

4 . The iron based powder according to claim 1 , wherein the maximum copper content in a cross section of a sintered component made from said iron based powder is at most 100% higher than the nominal copper content, wherein the sintered component is produced by mixing said iron-based powder with 0.5% of graphite, having a particle size, ×90, of at most 15 μm measured with laser diffraction according to ISO 13320:1999, and 0.9% of lubricant and the obtained mixture is transferred into a compaction die for production of tensile strength samples (TS-bars) according to ISO 2740: 2009 and subjected to a compaction pressure of 600 MPa and the compacted sample is thereafter ejected from the compaction die and subjected to a sintering process at 1120° C. for a period of time of 30 minutes in an atmosphere of 90% nitrogen/10% hydrogen at atmospheric pressure and the maximum copper content is determined through lines scanning in a Scanning Electron Microscope (SEM) equipped with a system for Energy Dispersive Spectroscopy (EDS), wherein the magnification is 130×, working distance is 10 mm and the scanning time is 1 minute.

5 . The iron based powder according to claim 1 , wherein the largest pore area in a cross section of a sintered component made from said iron based powder is at most 4 000 μm 2 wherein the sintered component is produced by mixing said iron-based powder with 0.5% of graphite, having a particle size, ×90, of at most 15 μm measured with laser diffraction according to ISO 13320:1999, and 0.9% of lubricant and the obtained mixture is transferred into a compaction die for production of tensile strength samples (TS-bars) according to ISO 2740: 2009 and subjected to a compaction pressure of 600 MPa and the compacted sample is thereafter ejected from the compaction die and subjected to a sintering process at 1120° C. for a period of time of 30 minutes in an atmosphere of 90% nitrogen/10% hydrogen at atmospheric pressure and the largest pore area is determined in a Light Optical Microscope (LOM) at a magnification of 100× with the aid of a digital video camera and a computer based software and the total measured area is 26.7 mm 2 .

6 . An iron-based powder composition containing or consisting of 10 to 99.8 weight % of the iron based powder according to claim 1 , optionally graphite up to 1.5% weight % and when graphite is present the content is 0.3-1.5 weight %-of lubricant and up to 1.0 weight % of machinability enhancing additives, balanced with iron powder.

7 . An iron-based powder composition containing or consisting of 50 to 99.8 weight % of the iron based powder according to claim 1 , optionally graphite up to 1.5% weight % and when graphite is present the content is 0.3-1.5 weight %-of lubricant and up to 1.0 weight % of machinability enhancing additives, balanced with iron powder.

8 . A process for producing an iron based powder comprising the following steps:
providing an iron powder having a content of oxygen of 0.3-1.2% by weight, a content of carbon of 0.1-0.5% by weight, a maximum particle size of at most 250 μm and at most 30% by weight below 45 μm and providing a copper containing powder having a maximum particle size, ×90 of at most 22 μm and a weight average particle size, ×50, of at most 15 μm, mixing said iron powder and said copper containing powder, subjecting said mixture to a reduction annealing process in a reducing atmosphere at 800-980° C. for a period of 20 minutes to 2 hours, and crushing the obtained cake and classifying into desired particle size.

9 . A process for making a sintered component comprising the steps of
providing an iron based powder composition according to claim 6 , subjecting the iron based powder composition to a compaction process at a compaction pressure of at least 400 MPa and ejecting the obtained green component, sintering said green component in a neutral or reducing atmosphere at a temperature of about 1050-1300° C. for a period of time of 10 to 75 minutes, and optionally hardening the sintered component in a hardening process such as case hardening, through hardening, induction hardening, or a hardening process including gas or oil quenching.

10 . A sintered component made according to claim 9 .

11 . The sintered component according to claim 10 , wherein the maximum copper content in a cross section is at most 100% higher than the nominal copper content, wherein the maximum copper content is determined through lines scanning in a Scanning Electron Microscope (SEM) equipped with a system for Energy Dispersive Spectroscopy (EDS), and wherein the magnification is 130×, working distance is 10 mm and the scanning time is 1 minute.

12 . The sintered component according to claim 10 , wherein the largest pore area is at most 4 000 μm 2 , and wherein the largest pore area is determined in a Light Optical Microscope (LOM) at a magnification of 100× with the aid of a digital video camera and a computer based software and the total measured area is 26.7 mm 2 .

Assignees

• Hoeganaes Ab Publ

Inventors

• Larsson Caroline
• Engström Ulf
• Szabo Christophe

Classifications

• B22F1/10

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title

• B22F1/05

  Metallic powder characterised by the size or surface area of the particles · CPC title

• B22F1/06

  Metallic powder characterised by the shape of the particles (nanosized particles B22F1/054) · CPC title

• B22F1/052

  characterised by a mixture of particles of different sizes or by the particle size distribution · CPC title

• B22F1/17 Primary

  Metallic particles coated with metal · CPC title