US20130152735A1 - Iron-based mixture powder for sintering and iron-based sintered alloy - Google Patents
Iron-based mixture powder for sintering and iron-based sintered alloy Download PDFInfo
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- US20130152735A1 US20130152735A1 US13/819,618 US201113819618A US2013152735A1 US 20130152735 A1 US20130152735 A1 US 20130152735A1 US 201113819618 A US201113819618 A US 201113819618A US 2013152735 A1 US2013152735 A1 US 2013152735A1
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- iron
- sintering
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- metal fluoride
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 265
- 239000000843 powder Substances 0.000 title claims abstract description 209
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 130
- 238000005245 sintering Methods 0.000 title claims abstract description 56
- 239000000203 mixture Substances 0.000 title claims abstract description 55
- 229910045601 alloy Inorganic materials 0.000 title abstract description 46
- 239000000956 alloy Substances 0.000 title abstract description 46
- 239000002245 particle Substances 0.000 claims abstract description 126
- 229910001512 metal fluoride Inorganic materials 0.000 claims abstract description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910001637 strontium fluoride Inorganic materials 0.000 claims description 55
- FVRNDBHWWSPNOM-UHFFFAOYSA-L strontium fluoride Chemical compound [F-].[F-].[Sr+2] FVRNDBHWWSPNOM-UHFFFAOYSA-L 0.000 claims description 54
- 229910001618 alkaline earth metal fluoride Inorganic materials 0.000 claims description 26
- 229920002050 silicone resin Polymers 0.000 claims description 10
- 238000005520 cutting process Methods 0.000 abstract description 56
- 238000004904 shortening Methods 0.000 abstract description 6
- 230000000116 mitigating effect Effects 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 19
- 238000012360 testing method Methods 0.000 description 15
- ZEKANFGSDXODPD-UHFFFAOYSA-N glyphosate-isopropylammonium Chemical compound CC(C)N.OC(=O)CNCP(O)(O)=O ZEKANFGSDXODPD-UHFFFAOYSA-N 0.000 description 11
- 238000000034 method Methods 0.000 description 11
- 238000010586 diagram Methods 0.000 description 8
- 238000010298 pulverizing process Methods 0.000 description 8
- 239000000314 lubricant Substances 0.000 description 7
- 229910052799 carbon Inorganic materials 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000003754 machining Methods 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 150000002505 iron Chemical class 0.000 description 4
- 229910052748 manganese Inorganic materials 0.000 description 4
- 239000002923 metal particle Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 229910052750 molybdenum Inorganic materials 0.000 description 4
- 238000000465 moulding Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 3
- 150000001342 alkaline earth metals Chemical class 0.000 description 3
- 239000013590 bulk material Substances 0.000 description 3
- -1 etc. Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- WGOROJDSDNILMB-UHFFFAOYSA-N octatriacontanediamide Chemical compound NC(=O)CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC(N)=O WGOROJDSDNILMB-UHFFFAOYSA-N 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- OYLGJCQECKOTOL-UHFFFAOYSA-L barium fluoride Chemical compound [F-].[F-].[Ba+2] OYLGJCQECKOTOL-UHFFFAOYSA-L 0.000 description 2
- 229910001632 barium fluoride Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005189 flocculation Methods 0.000 description 2
- 230000016615 flocculation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- YAFKGUAJYKXPDI-UHFFFAOYSA-J lead tetrafluoride Chemical compound F[Pb](F)(F)F YAFKGUAJYKXPDI-UHFFFAOYSA-J 0.000 description 2
- 238000005461 lubrication Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- LYRFLYHAGKPMFH-UHFFFAOYSA-N octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(N)=O LYRFLYHAGKPMFH-UHFFFAOYSA-N 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910052712 strontium Inorganic materials 0.000 description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000001479 atomic absorption spectroscopy Methods 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000009689 gas atomisation Methods 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- HGPXWXLYXNVULB-UHFFFAOYSA-M lithium stearate Chemical compound [Li+].CCCCCCCCCCCCCCCCCC([O-])=O HGPXWXLYXNVULB-UHFFFAOYSA-M 0.000 description 1
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- FATBGEAMYMYZAF-KTKRTIGZSA-N oleamide Chemical compound CCCCCCCC\C=C/CCCCCCCC(N)=O FATBGEAMYMYZAF-KTKRTIGZSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 235000003270 potassium fluoride Nutrition 0.000 description 1
- 239000011698 potassium fluoride Substances 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- LMDVZDMBPZVAIV-UHFFFAOYSA-N selenium hexafluoride Chemical compound F[Se](F)(F)(F)(F)F LMDVZDMBPZVAIV-UHFFFAOYSA-N 0.000 description 1
- 235000013024 sodium fluoride Nutrition 0.000 description 1
- 239000011775 sodium fluoride Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
Images
Classifications
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- B22F1/0003—
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0235—Starting from compounds, e.g. oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/06—Metallic powder characterised by the shape of the particles
- B22F1/068—Flake-like particles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- B22F1/105—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing inorganic lubricating or binding agents, e.g. metal salts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/12—Metallic powder containing non-metallic particles
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0207—Using a mixture of prealloyed powders or a master alloy
Definitions
- the present invention relates to iron-based mixture powders for sintering comprising at least an iron-based powder, a graphite powder, and a hard powder that is harder than the iron-based powder, and more particularly to iron-based mixture powders for sintering from which an iron-based sintered alloy with superior machinability may be sintered.
- iron-based mixture powders for sintering in which an iron-based powder, a graphite powder and a hard powder that is harder than the iron-based powder are mixed have occasionally been used.
- a compact is produced through pressure molding.
- an iron-based sintered alloy may be obtained.
- the carbon in the graphite powder dissolves in (forms a solid solution with) the iron-based powder, thereby hardening the iron-based powder.
- the iron of this hardened iron-based powder as a base, the hard powderis dispersed in the iron-based sintered alloy.
- the iron-based sintered alloy thus sintered undergoes cutting as required, and a finished product is obtained.
- the iron-based sintered alloy thus obtained is porous inside, and has higher cutting resistance as compared to metal alloys obtained through melting. Therefore, it has been conventional practice to further add to the mixture powder a powder containing S, such as BaS, CaS, MnS, etc., as a free-machining component.
- an iron-based mixture powderfor sintering in which, for example, instead of a powder containing S, a metal fluoride powder such as an alkaline earth metal fluoride powder, etc., is mixed (see, for example, PatentLiterature 1).
- An iron-based sintered alloy sintered from this iron-based mixture powder for sintering allows for improved machinability as a result of the metal fluoride powder's adhesion to recessed parts in the iron-based powder.
- Patent Literature 1 Even in cases where the metal fluoride powder disclosed in Patent Literature 1 is used, the particles of the metal fluoride powder would sometimes flocculate when mixed with the other powders of the iron-based mixture powder for sintering. Thus, when an iron-based sintered alloy in which the particles of the metal fluoride powder have flocculated is machined, this metal fluoride powder does not function sufficiently as a free-machining component and cutting resistance with respect to cutting tools rises, thereby potentially shortening cutting tool life.
- the present invention is made in view of such circumstances, and an aspect thereof lies in providing an iron-based mixture powder for sintering that is capable of, even when a metal fluoride powder is used, reducing the cutting resistance of the iron-based sintered alloy sintered therefrom and of mitigating the shortening of cutting tool life, as well as in providing an iron-based sintered alloy using same.
- the present inventors have, through diligent research, come to believe that, in mixing a metal fluoride powder in an iron-based mixture powder for sintering, it is preferable to disperse the metal fluoride particles within the iron-based mixture powder for sintering.
- the present inventors have further found that the shape of the particles is important for favorable dispersion of the metal fluoride particles, thatthe particles become more susceptible to flocculation the closer their shape becomes to being spherical, and that, conversely, the particles are more readily dispersed within the iron-based mixture powder for sintering the further their shape is from being spherical (i.e., the more recesses and projections they have).
- an iron-based mixture powder for sintering according to an embodiment of the present invention comprises: an iron-based powder; a graphite powder; a hard powder that is harder than the iron-based powder; and a metal fluoride powder, wherein, with respect to particle asperity as expressed by the follow equation,
- particle asperity (perimeter of a section of a particle) 2 /(sectional area of the section ⁇ 4Pi),
- the particle asperity of the metal fluoride powder is within a range of 2 to 5.
- the shape of the particles of the metal fluoride powder is one that readily adheres to (engages with) the iron-based particles and the hard particles.
- the particles of the metal fluoride powder to be mixed in the iron-based mixture powder for sintering thus become more readily dispersible (i.e., less likely to flocculate).
- a metal fluoride which serves as a free-machining component, is dispersed among the iron-based particles and the hard particles in an iron-based sintered alloy sintered from such an iron-based mixture powder for sintering, it is possible to reduce the cutting resistance of the iron-based sintered alloy and to mitigate the shortening of cutting tool life.
- the metal fluoride powder particles are prone to flocculation during mixing.
- Metal fluoride powder particles with an asperity exceeding 5 are difficult to produce.
- particle asperity is an index indicating the recess/projection shape of particles, where the asperity of a particle approaches 1 as the shape of the particle becomes closer to being spherical (i.e., as the section ofthe particle becomes closer to being a true circle).
- peripheral of a section of a particle refers to the perimeter of a given section of a particle (e.g., alkaline earth metal fluoride powder particle)
- sectional area of the section refers to the sectional area of the section as measured with respect to the aforementioned perimeter.
- iron-based is used in connection with the present invention to refer to a material whose principal component (base) is iron.
- examples of the metal fluoride powder may include potassium fluoride, sodium fluoride, calcium fluoride, magnesium fluoride, strontium fluoride, barium fluoride, lead fluoride, selenium fluoride, tellurium fluoride, etc.
- the metal fluoride powder may preferably be an alkaline earth metal fluoride powder, and the alkaline earth metal fluoride powder may further preferably be a strontium fluoride powder.
- the alkaline earth metal fluoride powder is dispersed without causing the sintered body to become brittle, and without dissolving in the iron base or disappearing due to gasification.
- strontium fluoride powders as compared to other metal fluoride powders (e.g., barium fluoride, lead fluoride, etc.), have a lower density, namely 4.24, and it is speculated that when the same amount(the same mass %) of a fluoride is added, its volume would be greatest as compared to others.
- the amount of strontium fluoride that comes into contactwith the other powders, such as the iron-based powder, the hard powder, etc. would increase, thereby improving the engagement with these powders. It is speculated that the machinability of the resultant iron-based sintered alloy would consequently improve as compared to those in which other metal fluorides are used.
- 0.5 to 3 mass % of the alkaline earth metal fluoride powder relative to the total amount of the iron-based mixture powder for sintering may preferably be contained. According to an embodiment of the present invention, by adding an alkaline earth metal fluoride powder, it is possible to reduce cutting resistance, improve cutting tool life, and, further, reduce surface damage to the sintered alloy.
- the alkaline earth metal fluoride powder content is less than 0.5 mass %, it may not, in some cases, be possible to improve the machinability of the resultant iron-based sintered alloy.
- it exceeds 3 mass % however, the alkaline earth metal fluoride powder becomes excessive, thereby increasing the likelihood of surface damage to the sintered alloy.
- the average particle size of theparticles of the alkaline earth metal fluoride powder may preferably be within the range of 1 to 20 micrometers. By keeping it within such a range, cutting resistance may be reduced and cutting tool life further improved, thereby making it possible to further reduce surface damage to the sintered alloy. Specifically, when the average particle size of (the particles of) the alkaline earth metal fluoride powder exceeds 20 micrometers, it becomes difficult for the alkaline earth metal fluoride to disperse at the grain boundary in the iron-based sintered alloy. This may result in increased cutting resistance and shortened cutting tool life, thereby increasing the likelihood of surface damage to the resultant sintered alloy.
- a lubricant, a binder, or the like may further be added to the iron-based mixture powder for sintering.
- a silicone resin may preferably be further added as the binder.
- silicone resins thermosetting resins, when a compact is produced by pressure molding the iron-based mixture powder for sintering and the compact is further sintered, it is possible to maintain the aforementioned binding force without the silicone resin softening. In addition, it is possible to maintain the aforementioned binding force even when a compact is produced through a warm mold lubrication method, or the like.
- FIG. 1 is a diagram showing projection views and the particle asperity of fluoride powders (particles of strontium fluoride powders) according to Example 1 and Comparative Example 1.
- FIG. 2 is a diagram showing the relationship between particle asperity and cutting tool wearwith respect to the strontium fluoride powders according to Example 1 and Comparative Example 1.
- FIG. 3 is an enlarged photograph of the metallographic structure of a specimen according to Example 2.
- FIG. 4A is a diagram showing test results for Example 3 and Comparative Example 2 with respect to cutting tool wear.
- FIG. 4B is a diagram showing test results for Example 3 and Comparative Example 2 with respect to cutting resistance.
- FIG. 4C is a diagram showing test results for Example 3 and Comparative Example 2 with respect to rattler value.
- FIG. 5A is a diagram showing test results for Example 4 and Comparative Example 2 with respect to cutting tool wear.
- FIG. 5B is a diagram showing test results for Example 4 and Comparative Example 2 with respect to cutting resistance.
- FIG. 5C is a diagram showing test results for Example 4 and Comparative Example 2 with respect to rattler value.
- a mixture powder according to an embodiment of the present invention may be an iron-based mixture powder for sintering for producing, through sintering, valve seats for internal combustion engines, etc.
- An iron-based mixture powder for sintering may be a mixture powder comprising an iron-based powder, a graphite powder, a hard powderthat is harder than the iron-based powder, and a metal fluoride powder.
- the iron-based powder may be a powder comprising particles whose principal component is iron, and may include a pure iron powder, such as an atomized iron powder, a reduced powder, etc., a steel powder in which an alloying element is pre-alloyed (pre-alloyed steel powder), a steel powder in which an alloying element is partially alloyed (partially alloyed steel powder), etc. Further, it may be a powder in which these powders are mixed.
- the iron-based powder forms the base of the iron-based sintered alloy. Further, the iron-based powder may preferably have an average particle size of 80 to 100 micrometers, and the iron-based powder content may preferably be 40 to 90 mass % relative to the total amount of the iron-based mixture powder for sintering.
- the graphite powder may be a powder containing graphite.
- C carbon
- an iron-based sintered alloy containing a suitable amount of C allows for such heat treatments as quenching and tempering, through which it is possible to improve the mechanical properties of the iron-based sintered alloy.
- C is not pre-contained in the iron-based powder for such reasons as the moldability of the raw powders, ease of adjusting C content, etc.
- the graphite powder may further contain a metal powder such as copper, etc., or an alloy powder.
- the graphite powder may preferably have an average particle size of 25 micrometers or below, andthe graphite powder content may preferably be 0.2 to 5 mass % relative to the total amount of the iron-based mixture powder for sintering. When the graphite powder content exceeds 5 mass %, ductility may drop significantly, and strength may drop.
- the hard powder may be a powder comprising hard particles that are harder than the iron particles of the iron-based powder. By dispersing the hard particles in the iron-based sinteredalloy, it is possible to improve the wear resistance of the iron-based sintered alloy.
- the hard particles constituting the hard powder may include: (1) particles comprising, in mass %, 20-70% Mo, 0.2-3% C, and 1-15% Mn, with the remainder comprising incidental impurities and Co; (2) particles comprising, in mass %, 20-70% Mo, 0.5-3% C, 5-40% Ni, and 1-20% Mn, with the remainder comprising incidental impurities and Fe; (3) particles comprising,in mass %, 20-60% Mo, 0.2-3% C, 5-40% Ni, 1-15% Mn, and 0.1-10% Cr, with the remainder comprising incidental impurities and Fe; (4) particles comprising, in mass %, 20-40% Mo, 0.5-1.0%C, 5-30% Ni, 1-10% Mn, 1-10% Cr, 5-30
- the hard particles are harder than the iron particles, and Si, etc., by way of example, may further be included in addition to these particles.
- the hard powder may preferably have an average particle size of 80 to 120 micrometers, and the hard powder content may preferably be 10to 60 mass % relative to the total amount of the iron-based mixture powder for sintering.
- a strontium fluoride powder (a powder comprising particles of strontium fluoride) is prepared as an alkaline earth metal fluoride powder (a powder comprising particles of an alkaline earth metal fluoride).
- Alkaline earth metal fluoride powders, such as strontium fluoride powders, etc., used in metallurgy, such as sintering, etc. have hitherto been produced generally by precipitating alkaline earth metal fluoride particles from a solution in which an alkaline earth metal is dissolved in hydrogen fluoride, and particles of such powders have shapes that are close to being spherical.
- a bulk material in which crystals of strontium fluoride (an alkaline earth metal) are consolidated, or a bulk material obtained by melting them, is pulverized with a mill, etc., to produce particles having recesses and projections.
- pulverizing conditions such as the shape of the pulverizing part of the mill, the pulverizing load, etc., were so selected that the asperity of the strontium fluoride particles would fall within the range of 2 to 5, and strontium fluoride was thus produced. It is noted that as the asperity of the particles approaches 1, the particles become more spherical. With respect to methods in which strontium fluoride particles are precipitated, particle asperity is extremely close to 1.
- the particle asperity of the strontium fluoride powder is made to fall within the range of 2 to 5
- the shape of the particles of the strontium fluoride powder is conducive to adhesion with the iron-based particles and the hard particles. Consequently, with respect to the iron-based mixture powder for sintering, the particles of the strontium fluoride powder to be mixed become readily dispersible (less likely to flocculate).
- strontium fluoride which serves as a free-machining component, is dispersed among the iron-based particles and the hard particles in the iron-based sintered alloy sintered from this iron-based mixture powder for sintering, it is possible to reduce the cutting resistance of the iron-based sintered alloy and to mitigate the shortening of cutting tool life.
- the strontium fluoride powder content may preferably be 0.5 to 3 mass % relative tothe total amount of the iron-based mixture powder for sintering, and the average particle size of the strontium fluoride powder may preferably be within the range of 1 to 20 micrometers.
- a lubricant, a binder, etc. may further be added to the iron-based mixture powder for sintering.
- a silicone resin e.g., one that is methyl-based
- this resin may preferably be addedby diluting it with an organic solvent, mixing it with an iron powder and strontium fluoride, and removing any excessive organic solvent through heating and drying.
- the silicone resincontent may preferably be 1 mass % or less relative to the total amount of the iron-based mixture powder for sintering.
- silicone resins are thermosetting resins, in producing a compact by pressure molding the iron-based mixture powder for sintering and then further sintering the compact, it is possible to maintain the aforementionedbinding force without the silicone resin softening. In addition, it is possible to maintainthe aforementioned binding force even when a compact is produced through a warm mold lubrication method, etc., since they are resistant to temperatures of at least 150 degrees C.
- the iron-based mixture powder for sintering may contain, for the lubricant, a thermoplastic resin powder, zinc stearate, lithium stearate, stearic acid, oleic acid amide, stearic acid amide, a molten mixture of stearic acid amide and ethylenebis stearic acid amide, ethylenebis stearic acid amide, polyethylene with a molecular mass of ten thousand or less, or a molten mixture of ethylenebis stearic acid amide and polyethylene with a molecular mass of ten thousand or less.
- An iron-based mixture powder for sintering was produced by mixing an iron-based powder, a graphite powder, a hard powder that is harder than the iron-based powder, a metal fluoride powder, and a lubricant.
- an iron-based powder (Fe)—1.1 mass % graphite powder (Gr)—30 mass % hard powder—1 mass % strontium fluoride powder (SrF 2 )—0.8 mass % lubricant (ZnSt) were prepared.
- the iron-based powder was a pure iron powder produced through a reductive method, and the iron-based particles forming the iron-based powder were a powder with an average particle size of 100 micrometers.
- the hard powder was produced through a gas atomization method, and the hard particles forming the hard powder comprised: 0.8 mass % C—1.1 mass % Si—5.1 mass % Mn—21 mass % Ni—6 mass % Cr—39 mass % Mo—22 mass % Co—4.5 mass % Fe—0.2 mass % Y.
- the hard powder was a powder with an average particle size of 100 micrometers.
- the strontium fluoride powder was produced by pulverizing, with a mill, etc., a bulk material into which strontium fluoride (alkaline earth metal) crystals had been consolidated.
- the particles of this powder were particles having recesses and projections and an average particle size of 5 micrometers. Further, defining powder particle asperity as being:
- powder particle asperity (perimeter of a section of a particle) 2 /(sectional area of the section ⁇ 4Pi),
- FIG. 1 An image of a strontium fluoride particle with an asperity of 2.65, which is one of the Examples, is shown in FIG. 1 .
- iron-based mixture powders for sintering were pressure molded at 784 MPa and at room temperature, and thereafter sintered at 1120 degrees C. to obtain specimens made of an iron-based sintered alloy and that were of a shape corresponding to a valve seat.
- the average particle size was measured through a sieving method. Specifically, using JIS Z8801-1compliant test sieves, the sizes of the particles were determined based on the size of the openings in the mesh that were passed. Specifically, by sieving using several kinds of sieves with varying mesh sizes, particle size distribution, by mass, was determined by computing the weight ratio on each sieve.
- a specimen made of an iron-based sintered alloy was produced in a similar fashion to Example1. Differences with respect to the Example lie in the strontium fluoride powder.
- the strontium fluoride powder in Comparative Example 1 was a powder that was obtained by precipitating alkaline earth metal fluoride particles from a solution in which strontium fluoride was dissolved in hydrogen fluoride, and whose particle asperity was 1.0.
- An image of a strontium fluoride particle of Comparative Example 1 with an asperity of 1.0 is shown inFIG. 1.
- 300 passes' worth of a cutting process (where one pass corresponds to the cutting length forone valve seat) was performed with respect to specimens of Example 1 and Comparative Example1 at a feed rate of 0.3 mm and a cutting speed of 0.08 mm/rev using a cutting tool (material: carbide). Then, using an optical microscope, the greatest depth of wear of the flank faceof the cutting tool was measured as cutting tool wear Vbmax. The results are shown in FIG. 2 .
- Example 1 There was less cutting tool wear in Example 1 as compared to Comparative Example 1. It is speculated that this is because strontium fluoride powders comprising particles with an asperity of 2 to 5 are of such shapes that readily adhere to (engage with) the iron-based particles and the hard particles, and the particles of the strontium fluoride powders to be mixed are more readily dispersible (less likely to flocculate) in the iron-based mixture powder forsintering.
- Example 2 The specimen of Example 2 was cut out, and a section thereof was observed using an electron microscope. The result is shown in FIG. 3 .
- the Sr- and F-contents (the amounts added) of the specimen of Example 2 were measured through X-ray atomic absorption spectroscopy.
- the results are presented in Table 1 below. It is noted that, of the values presented in Table 1, the theoretical values indicate the respective proportions (in mass %) of Sr and F relative to 1 mass % of the strontium fluoride powderthat has been added, and that the analytical values indicate the respective proportions (in mass %) of Sr and F as measured.
- the values in parentheses provided with the analytical values indicate values calculated by dividing the analytical values with the respective theoretical values.
- strontium fluoride SrF 2
- SrF 2 strontium fluoride
- Table 1 even after sintering, morethan 85% of the strontium fluoride remained. From such results, it is speculated that the machinability of the iron-based sintered alloy would improve dramatically by virtue of the dispersed strontium fluoride.
- Example 1 Specimens made of an iron-based sintered alloy were produced in a similar fashion to Example1. Differences with respect to Example 1 lie in the fact that, by changing the pulverization conditions, there were produced powders whose particle asperity of the strontium fluoride powder was 2.7, and in the fact that 0.5 mass % to 5.0 mass % of the strontium fluoride powder was added as shown in FIG. 4 . The average particle size was 5 micrometers for all strontium fluoride powders.
- Example 1 A specimen made of an iron-based sintered alloy was produced in a similar fashion to Example1. Differences with respect to Example 1 lie in the fact that no strontium fluoride powder was added to the iron-based mixture powder for sintering.
- Cutting tool wear tests were performed with respect to the specimens of Example 3 and Comparative Example 2 in a similar fashion to Example 1. To that end, using a cutting resistance measuring method, cutting resistance was measured with a dynamometer attached to a cutting tool fixing part. Cutting tool wear and cutting resistance are respectively presented in FIG. 4A and FIG. 4B .
- Example 3 exhibited less cutting tool wear and cutting resistance as compared to Comparative Example 2. Further, as shown in FIG. 4C , of the specimens of Example 3, the specimen whose amount added was 5 mass % exhibited a rattler value exceeding 20%, which was greater than those of the other specimens. From these results, it may be inferred that, in order to improve the machinability of the iron-based sintered alloy by way of strontium fluoride, 0.5 mass % or more of strontium fluoride may preferably be added. Further, in order to reduce the susceptibility to surface damage of the iron-based sintered alloy, 3.0 mass % or less of strontium fluoride may preferably be added, or 1.5 mass % or less may further preferably be added.
- strontium fluoride SrF 2
- Example 1 Specimens made of an iron-based sintered alloy were produced in a similar fashion to Example1. Differences with respect to Example 1 lie in the fact that, by changing the pulverization conditions, there were produced powders whose particle asperity of the strontium fluoride powder was 2.7, and in the fact that the particle sizes of the particles of these powders were made to be such that their average particle sizes fell within the range of 1 to 100 micrometers as shown in FIGS. 5A through 5C . Particles with average particles sizes of 50 micrometers to 100 micrometers were granulated using a liquid adhesive (PVP) as a method of varying particle size. For the other particles, predetermined particle sizes were selected through grading using sieves. It is noted that the amount of strontium fluoride powder added was 1.0 mass %.
- PVP liquid adhesive
- a cutting tool wear test and a rattler test were conducted with respect to the specimens of Example 4 as in Example 3.
- Cutting tool wear, cutting resistance, and rattler values are indicated in FIG. 5A , FIG. 5B , and FIG. 5C , respectively.
- the results for Comparative Example2 are also indicated in FIGS. 5A through 5C .
- Example 4 exhibited less cutting tool wear and cutting resistance as compared to Comparative Example 2.
- SrF 2 strontium fluoride
- Example 4 exhibited less cutting tool wear and cutting resistance as compared to Comparative Example 2.
- FIG. 5A As the average particle sizes of the powders of Example 4 increased, cutting tool wear also increased.
- FIG. 5B As the average particle size increased to 50 micrometers and 100 micrometers, cutting resistance increased.
- FIG. 5C As the average particle size increased to 50 micrometers and 100 micrometers, the rattler value also increased.
- the average particle size of (the particles of) the strontium fluoride powder is 5 micrometers or less, the degree to which strontium fluoride contributes as a solid lubricant during sintering is greater. Further, it is speculated that, asthe average particle size of the strontium fluoride powder increases to a certain level (as it exceeds 20 micrometers), it inhibits engagement among the iron powder particles instead of contributing as a solid lubricant.
- perimeters of sections (largest sections) of particles, and sectionalareas of such sections were measured using projected images of particles as observed with a microscope.
- the present invention is by no means limited to such a method as long as asperity may be measured by directly measuring perimeters and sections, for example.
- the present invention may be suitably used in valve systems (e.g., valve seats, valve guides) of engines that run on compressed natural gas or gasoline and which are placed under high temperature use conditions.
- valve systems e.g., valve seats, valve guides
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JP2010194116A JP2012052167A (ja) | 2010-08-31 | 2010-08-31 | 焼結用鉄基混合粉末及び鉄基焼結合金 |
PCT/JP2011/004777 WO2012029274A2 (en) | 2010-08-31 | 2011-08-29 | Iron-based mixture powder for sintering and iron-based sintered alloy |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150104346A1 (en) * | 2013-10-11 | 2015-04-16 | Seiko Epson Corporation | Laser sintering powder, method for producing structure, apparatus for producing structure |
US20180141117A1 (en) * | 2015-05-27 | 2018-05-24 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Mixed powder for iron-based powder metallurgy, method for producing same, sintered body produced using same, and method for producing sintered body |
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JP5637201B2 (ja) * | 2012-11-14 | 2014-12-10 | トヨタ自動車株式会社 | 焼結合金配合用硬質粒子、耐摩耗性鉄基焼結合金、及びその製造方法 |
JP6502085B2 (ja) * | 2014-12-19 | 2019-04-17 | Ntn株式会社 | 圧粉体及びその製造方法 |
JP7069800B2 (ja) * | 2018-02-16 | 2022-05-18 | 大同特殊鋼株式会社 | 焼結体用硬質粒子粉末 |
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US5512080A (en) * | 1992-11-27 | 1996-04-30 | Toyota Jidosha Kabushiki Kaisha | Fe-based alloy powder adapted for sintering, Fe-based sintered alloy having wear resistance, and process for producing the same |
US6802883B2 (en) * | 2002-03-12 | 2004-10-12 | Kabushiki Kaisha Riken | Iron-based sintered alloy for use as valve seat and its production method |
US7241327B2 (en) * | 2004-05-17 | 2007-07-10 | Riken Corporation | Iron-based sintered alloy with dispersed hard particles |
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US6144820A (en) * | 1998-04-17 | 2000-11-07 | Canon Kabushiki Kaisha | Developing apparatus with a sealing member having an insulating layer and a conductive portion |
JPH11344859A (ja) * | 1998-05-29 | 1999-12-14 | Canon Inc | 現像装置およびプロセスカートリッジおよび画像形成装置 |
JP3952344B2 (ja) * | 1998-12-28 | 2007-08-01 | 日本ピストンリング株式会社 | バルブシート用耐摩耗性鉄基焼結合金材および鉄基焼結合金製バルブシート |
JP3873609B2 (ja) * | 2000-11-17 | 2007-01-24 | Jfeスチール株式会社 | 粉末冶金用鉄基混合粉および鉄基焼結体 |
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2011
- 2011-08-29 WO PCT/JP2011/004777 patent/WO2012029274A2/en active Application Filing
- 2011-08-29 CN CN2011800414603A patent/CN103080349A/zh active Pending
- 2011-08-29 US US13/819,618 patent/US20130152735A1/en not_active Abandoned
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US5512080A (en) * | 1992-11-27 | 1996-04-30 | Toyota Jidosha Kabushiki Kaisha | Fe-based alloy powder adapted for sintering, Fe-based sintered alloy having wear resistance, and process for producing the same |
US6802883B2 (en) * | 2002-03-12 | 2004-10-12 | Kabushiki Kaisha Riken | Iron-based sintered alloy for use as valve seat and its production method |
US7491256B2 (en) * | 2004-04-26 | 2009-02-17 | Höganäs Ab | Iron-based powder composition |
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US20150104346A1 (en) * | 2013-10-11 | 2015-04-16 | Seiko Epson Corporation | Laser sintering powder, method for producing structure, apparatus for producing structure |
US20180141117A1 (en) * | 2015-05-27 | 2018-05-24 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Mixed powder for iron-based powder metallurgy, method for producing same, sintered body produced using same, and method for producing sintered body |
Also Published As
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CN103080349A (zh) | 2013-05-01 |
JP2012052167A (ja) | 2012-03-15 |
WO2012029274A3 (en) | 2012-04-26 |
WO2012029274A2 (en) | 2012-03-08 |
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