CN100516271C

CN100516271C - Sintered valve guide and manufacturing method thereof

Info

Publication number: CN100516271C
Application number: CNB2005100842015A
Authority: CN
Inventors: 近畑克直; 林幸一郎; 藤塚裕树; 坪井彻
Original assignee: Hitachi Powdered Metals Co Ltd
Current assignee: Resonac Holdings Corp
Priority date: 2004-07-15
Filing date: 2005-07-15
Publication date: 2009-07-22
Anticipated expiration: 2025-07-15
Also published as: EP1619263B1; CN1721566A; KR20060050208A; EP1619263A1; US20060032328A1

Abstract

Disclosed is a sintered valve guide guide formed of a sintered alloy consisting essentially of 3.5 to 5% copper, 0.3 to 0.6% tin, 0.04 to 0.15% phosphorus, 1.5 to 2.5% carbon and the balance iron, by mass, and as occasion needs, further containing 0.46 to 1.41% metal oxide, and MnS and/or magnesium silicate. The metallographic structure has: a matrix containing a pearlite phase, a Fe-P-C compound phase and a Cu-Sn alloy phase; pores; and a graphite of 1.2 to 1.7% by mass of the sintered alloy. In the cross section, the ratio of the pearlite phase to the matrix is 90 area % or more, the ratio of the Fe-P-C compound phase is 0.1 to 3 area % of the cross section, the ratio of the Cu-Sn alloy phase to the cross section is 1 to 3% by area, and the ratio of a portion of the Fe-P-C compound phase having a thickness of 15 microns or more is 10 area % or less of the whole Fe-P-C compound phase.

Description

Sintered valve guide and manufacture method thereof

Technical field

The valve that the present invention relates to be used for oil engine is led, and especially, relates to a kind of sintered valve guide of being made by the sintered alloy with good abrasion resistance properties and machinability, and manufacture method.

Background technology

Led being applied in the oil engine by castiron valve, recently, the sintered alloy valve is led owing to its abrasion resistance properties and mass production are used in the past.For example, applicant of the present invention just once disclosed the outstanding sintered valve guide material of abrasion resistance properties in Japanese Patent Publication 55-34858 communique and No. 2680927 communique of special permission.

Disclosed valve is led the moiety of material and is in the public clear 55-34858 communique of spy, with weight ratio, C:1.5～4%, Cu:1～5%, Sn:0.1～2%, P:0.1～0.3%, and Fe: surplus, its structure is, in the matrix that mixes by perlite and ferrite, be dispersed with, the iron-phosphorus-carbon compound phase that constitutes by the cocrystalization compound of Fe-P-C, Cu-Sn mutually and free graphite mutually.It has than traditional cast iron valve leads better abrasion resistance properties and than the better machinability of conventional iron base sintered alloy, although it is difficult to processing than cast prod is relative, is used in many automobile factorys.

On the other hand, specially permit in No. 2680927 communique disclosed valve and lead material, be that valve in the special public clear 55-34858 communique is led the improvement of material, lead disperse Magnesium Silicate q-agent mineral on the crystal boundary of material by the valve in the public clear 55-34858 communique of spy, under the prerequisite that does not influence abrasion resistance properties, improve machinability.

Disclosed valve is led bill of material and is revealed excellent abrasion resistance properties in No. 2680927 communique of special permission, and to lead material suitable with the valve in the public clear 55-34858 communique of spy, although its machinability improves, but than cast prod difference.Therefore, hope can further improve machinability.The application's applicant even lost abrasion resistance properties to a certain extent, also will be conceived to improve machinability by research, thereby has developed and driven in the 2002-69597 communique disclosed valve the spy and lead material.

Drive disclosed valve in the 2002-69597 communique the spy and lead the moiety of material and be, by weight, C:1.5～4%, Cu:1～5%, Sn:0.1～0.2%, P:0.01～0.1%, and Fe: surplus, its structure are that free graphite is scattered here and there in the matrix based on perlite.

But,, improve valve and lead the processibility of material and valve is led the demand of the good machinability of material also in continuous growth along with the efficient that improves the course of processing.

Summary of the invention

In view of the above problems, the purpose of this invention is to provide a kind of novel sintered valve leads, it has increased durability, and can lead material as valve and can effectively make by the sintered alloy that use has isostatic abrasion resistance properties and a machinability, with and manufacture method.

To achieve these goals, according to an aspect of the present invention, a kind of sintered valve guide is made by sintered alloy, the essentially consist of this sintered alloy is in mass, copper: 3.5～5%, tin: 0.3～0.6%, phosphorus: 0.04～0.15%, carbon: 1.5～2.5, iron: surplus, wherein sintered alloy has metallographic structure, it comprises: by the perlite phase, the matrix that Fe-P-C compound phase and Cu-Sn alloy phase constitute, the graphite of pore and the disperse that accounts for sintered alloy mass ratio 1.2～1.7% mutually, wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix alloy area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area smaller or equal to 10%.

According to a further aspect in the invention, a kind of sintered valve guide, make by sintered alloy, the essentially consist of this sintered alloy is in mass, copper: 3.5～5%, tin: 0.3～0.6%, phosphorus: 0.04～0.15%, carbon: 1.5～2.5, metal oxide: 0.46～1.41%, iron: surplus, wherein sintered alloy has metallographic structure, it comprises: by the perlite phase, Fe-P-C compound phase, the matrix that Cu-Sn alloy phase and metal oxide constitute mutually, the graphite of pore and the disperse that accounts for sintered alloy mass ratio 1.2～1.7% mutually, wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix alloy area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area smaller or equal to 10%.

According to a further aspect in the invention, a kind of sintered valve guide, it is made by sintered alloy, the essentially consist of sintered alloy is in mass, copper: 3.5～5%, tin: 0.3～0.6%, phosphorus: 0.04～0.15%, carbon: 1.5～2.5, be less than and equal 1.6% at least a solid lubricant in manganese sulfide and the Magnesium Silicate q-agent mineral that is selected from, iron: surplus, wherein sintered alloy has metallographic structure, it comprises: by the perlite phase, Fe-P-C compound phase, the matrix that Cu-Sn alloy phase and metal oxide constitute mutually, pore, account for the graphite phase of the disperse of sintered alloy mass ratio 1.2～1.7%, and described at least a solid lubricant, this lubricant is distributed in pore or is distributed in the crystal boundary of metallographic structure, and wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix alloy area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, the graphite that is distributed in pore account for mutually metallographic structure cross-sectional area 0.8～3.2%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area 10% or still less.

According to a further aspect in the invention, a kind of sintered valve guide, it is made by sintered alloy, the essentially consist of sintered alloy is in mass, copper: 3.5～5%, tin: 0.3～0.6%, phosphorus: 0.04～0.15%, carbon: 1.5～2.5, metal oxide: 0.46～1.41%, be less than and equal 1.6% at least a solid lubricant in manganese sulfide and the Magnesium Silicate q-agent mineral that is selected from, iron: surplus, wherein sintered alloy has metallographic structure, it comprises: by the perlite phase, Fe-P-C compound phase, the matrix that Cu-Sn alloy phase and metal oxide constitute mutually, pore, account for the graphite phase of the disperse of sintered alloy mass ratio 1.2～1.7%, and described at least a solid lubricant, lubricant is distributed in pore or is distributed in the crystal boundary of sintered alloy metallographic structure; Wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix alloy area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, the graphite that is distributed in pore account for mutually metallographic structure cross-sectional area 0.8～3.2%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area 10% or still less.

According to an aspect of the present invention, a kind of manufacture method of sintered valve guide, it comprises: the preparation powdered mixture, composition is the Fe-P powdered alloy in mass: 0.27～0.7%, and Cu-Sn powdered alloy: 3.93～5.44%, powdered graphite: 1.7～2.7%, iron powder: surplus; Wherein, Fe-P powder powder is made up of the iron of 15～21% phosphorus, unavoidable impurities and surplus in fact; The Cu-Sn powdered alloy is made up of the copper of 8～11% tin, unavoidable impurities and surplus in fact; Powdered mixture is compressed in tubular intracavity, and powdered mixture forms the tubulose compacts; With tubulose compacts sintering in non-oxidizing atmosphere, sintering temperature is 950～1050 ℃ then.

According to said process, can be good, the valve of isostatic abrasion resistance properties and cutting ability leads material, effectively makes the sintered valve guide with increased durability by having.

Description of drawings

Fig. 1 is the sectional schematic diagram of the metallographic structure of sintered valve guide of the present invention.

Fig. 2 is the sectional schematic diagram of metallographic structure with sintered valve guide of higher proportion iron-phosphorus-carbon compound phase.

Fig. 3 A-3D is the relation curve of the ratio (Fig. 3 D) of the amount (Fig. 3 C) of ratio (Fig. 3 B), free graphite phase of mutually content ratio (Fig. 3 A) of phosphorus content and iron-phosphorus-carbon compound, copper-tin alloy phase in total composition and ferritic phase.

Fig. 4 A-4D is the relation curve of phosphorus content and iron-phosphorus-carbon compound formation (Fig. 4 A), abrasion loss (Fig. 4 B), machinability index (Fig. 4 C) and radial crushing strength constant (Fig. 4 D) mutually in total composition.

Fig. 5 A-5D is the relation curve of the ratio (Fig. 5 D) of the amount (Fig. 5 C) of ratio (Fig. 5 B), free graphite phase of mutually ratio (Fig. 5 A) of tin content and iron-phosphorus-carbon compound, copper-tin alloy phase in total composition and ferritic phase.

Fig. 6 A-6D is the relation curve of tin content and iron-phosphorus-carbon compound formation (Fig. 6 A), abrasion loss (Fig. 6 B), machinability index (Fig. 6 C) and radial crushing strength constant (Fig. 6 D) mutually in total composition.

Fig. 7 A-7D is the relation curve of the ratio (Fig. 7 D) of the amount (Fig. 7 C) of ratio (Fig. 7 B), free graphite phase of mutually ratio (Fig. 7 A) of copper content and iron-phosphorus-carbon compound, copper-tin alloy phase in total composition and ferritic phase.

Fig. 8 A-8D is the relation curve of copper content and iron-phosphorus-carbon compound formation (Fig. 8 A), abrasion loss (Fig. 8 B), machinability index (Fig. 8 C) and radial crushing strength constant (Fig. 8 D) mutually in total composition.

Fig. 9 A-9D is the relation curve of the ratio (Fig. 9 D) of the amount (Fig. 9 C) of ratio (Fig. 9 B), free graphite phase of mutually ratio (Fig. 9 A) of carbon content and iron-phosphorus-carbon compound, copper-tin alloy phase in total composition and ferritic phase.

Figure 10 A-10D is the relation curve of carbon content and iron-phosphorus-carbon compound formation (Figure 10 A), abrasion loss (Figure 10 B), machinability index (Figure 10 C) and radial crushing strength constant (Figure 10 D) mutually in total composition.

Figure 11 A-11D is a sintering temperature and the relation curve of the ratio (Figure 11 D) of the amount (Figure 11 C) of the ratio (Figure 11 B) of mutually ratio (Figure 11 A) of iron-phosphorus-carbon compound, copper-tin alloy phase, free graphite phase and ferritic phase.

Figure 12 A-12D is a sintering temperature and the relation curve of iron-phosphorus-carbon compound formation (Figure 12 A), abrasion loss (Figure 12 B), machinability index (Figure 12 C) and radial crushing strength constant (Figure 12 D) mutually.

Figure 13 A-13D is a sintering time and the relation curve of the ratio (Figure 11 D) of the amount (Figure 13 C) of the ratio (Figure 13 B) of mutually ratio (Figure 13 A) of iron-phosphorus-carbon compound, copper-tin alloy phase, free graphite phase and ferritic phase.

Figure 14 A-14D is a sintering time and the relation curve of iron-phosphorus-carbon compound formation (Figure 14 A), abrasion loss (Figure 14 B), machinability index (Figure 14 C) and radial crushing strength constant (Figure 14 D) mutually.

Figure 15 A-15D is a speed of cooling and the relation curve of the ratio (Figure 15 D) of the amount (Figure 15 C) of the ratio (Figure 15 B) of mutually ratio (Figure 15 A) of iron-phosphorus-carbon compound, copper-tin alloy phase, free graphite phase and ferritic phase.

Figure 16 A-16D is a speed of cooling and the relation curve of iron-phosphorus-carbon compound formation (Figure 16 A), abrasion loss (Figure 16 B), machinability index (Figure 16 C) and radial crushing strength constant (Figure 16 D) mutually.

Figure 17 A-17D is the relation curve of the ratio (Figure 17 D) of the amount (Figure 17 C) of ratio (Figure 17 B), free graphite phase of mutually ratio (Figure 17 A) of oxide content and iron-phosphorus-carbon compound, copper-tin alloy phase in the iron powder and ferritic phase.

Figure 18 A-18D is the relation curve of oxide content and iron-phosphorus-carbon compound formation (Figure 18 A), abrasion loss (Figure 18 B), machinability index (Figure 18 C) and radial crushing strength constant (Figure 18 D) mutually in the iron powder.

Figure 19 A-19D is the atomized iron powder amount and the relation curve of the ratio (Figure 19 D) of the amount (Figure 19 C) of the ratio (Figure 19 B) of mutually ratio (Figure 19 A) of iron-phosphorus-carbon compound, copper-tin alloy phase, free graphite phase and ferritic phase.

Figure 20 A-20D is the atomized iron powder amount and the relation curve of iron-phosphorus-carbon compound formation (Figure 20 A), abrasion loss (Figure 20 B), machinability index (Figure 20 C) and radial crushing strength constant (Figure 20 D) mutually.

Figure 21 A-21D is the relation curve of the ratio (Figure 21 D) of the amount (Figure 21 C) of ratio (Figure 21 B), free graphite phase of mutually the ratio (Figure 21 A) of amount and iron-phosphorus-carbon compound of improving the powder of machinability component, copper-tin alloy phase and ferritic phase.

Figure 22 A-22D is the relation curve of amount and iron-phosphorus-carbon compound formation (Figure 22 A), abrasion loss (Figure 22 B), machinability index (Figure 22 C) and radial crushing strength constant (Figure 22 D) mutually that improves the powder of machinability component.

Embodiment

The sintered alloy of being made by powder metallurgy according to forming and use the particle diameter of raw material and create conditions, such as Heating temperature etc., has different each other metallographic structure.Even overall composition is identical, and the performance of material such as the physical strength of sintered alloy, depends on the structure of sintered alloy strongly.Among the present invention, consider the material behavior of each phase in the sintered alloy, when valve design is led the metallographic structure of material, consider that final valve is led the needed material behavior of material authorizes sintered alloy, and this basis that will become definite raw material and create conditions.

Valve is led and is required to have high strength and high abrasion resistance.Be used for the conventional alloys that valve leads and satisfy this two requirements, but aspect machinability deficiency, so user's strong request improves these deficiencies in the processing.So, in order to satisfy user's demand, the objective of the invention is, based on iron be the matrix of main component and contain for copper-tin alloy phase of improving abrasion resistance properties, iron-phosphorus-carbon compound mutually and free graphite alloy mutually, improve the machinability that valve is led.Below, the metallographic structure that is used for the sintered alloy of sintered valve guide of the present invention is elaborated.It should be noted that the ratio of each phase in the section of following metallographic structure is the mean value of area %.

In order to improve intensity, the matrix of sintered alloy is made of pearlitic structure, perlite during by raw material iron powder and powdered graphite sintering carbon be diffused in the raw material iron powder and form.Because when containing carbon as sosoloid in the metal-powder, hard and compression is so select iron powder and powdered graphite as raw material.If the quantity not sufficient of powdered graphite will cause that the amount of the carbon that engages with matrix metal reduces, thereby cause making the strength degradation of matrix owing in matrix, having formed a large amount of ferrite (α-iron).As described later, it should be noted that at formation iron-phosphorus-carbon compound mutually often with a little ferrite formation around the steadite phase.But, if perlite occupies 90% or above area ratio in matrix, all the other cable bodies for forming, this also is the acceptable scope, because very little to the reduction of the intensity of matrix.

Iron-phosphorus-carbon compound phase disperse is in pearlite matrix.By iron-phosphorus alloy powder is mixed mutually with the raw material iron powder, carry out sintering together with powdered graphite, iron-phosphorus-carbon compound is separated out with film like on the crystal boundary of perlite phase, has formed hard iron-phosphorus-carbon compound phase, and has improved the abrasion resistance properties of sintered alloy.Area ratio on the section of iron-phosphorus-carbon compound in metallographic structure reaches 0.1% or more for a long time, the raising of abrasion resistance properties is more remarkable.On the other hand, the increase of the formation amount of iron-phosphorus-carbon compound phase causes the increase of film thickness, thereby forms flaky iron-phosphorus-carbon compound phase, and the result is the rapid deterioration of the machinability of sintered alloy.Therefore, reduce the amount of iron-phosphorus-carbon compound phase, and iron-phosphorus-carbon compound is dispersed into the decline that film like prevents the sintered alloy machinability mutually is crucial.Particularly on the section of metallographic structure, iron-phosphorus-carbon compound should account for 3 area % or lower of metallographic structure section mutually, and iron-phosphorus-carbon compound phase that thickness meets or exceeds 15 μ m should account for 10 area % or lower of total iron-phosphorus-carbon compound phase.More specifically, iron-phosphorus-carbon compound that thickness meets or exceeds 15 μ m is preferably the 0.1 area % that is no more than of total iron-phosphorus-carbon compound phase mutually, another part thickness is more than or equal to 5 μ m, preferably account for 10～40 area % less than 15 μ m, other are iron-phosphorus-carbon compound phase of thickness less than 5 μ m, and the preferential such tissue of formation of selecting.Iron-phosphorus-carbon compound will be captured the carbon in the pearlite matrix in growth, make to produce some ferrites mutually on every side at iron-phosphorus-carbon compound.The amount that the ferrite that intensity is low can allow in the matrix of sintered alloy is smaller or equal to 10 area %, but does not wish the ferrite of volume.If the too high levels of phosphorus in raw material powder will cause generating thick iron-phosphorus-carbon compound phase, but simultaneously, by capturing the carbon in the perlite, the low ferritic amount of intensity that is scattered in the matrix increases.Therefore the amount of iron-phosphorus-carbon compound phase that should conscientiously control generation to be to prevent the above-described problem from occurring, and particularly, the ratio that iron-phosphorus-carbon compound accounts for the section of metallographic structure mutually should remain on the scope of 0.1～3 area %.Therefore, should to adjust to phosphorus content be 0.04～0.15 quality % in sintered alloy to the amount of the iron of use-phosphorus alloy powder.If the intensity of laying particular stress on or wear resistance, the amount of iron-phosphorus alloy are 0.1～0.15 quality %,, then be 0.04～0.1 quality % if lay particular stress on machinability.

Among the present invention, copper-tin alloy is scattered in the sintered alloy mutually.Copper-tin alloy is soft, by the consistency of raising and valve or slide unit, can effectively improve the wearability of sintered alloy.When copper-tin alloy is distributed in the sintered alloy mutually, reach 1 area % of metallographic structure section or more for a long time, its effect is more remarkable.But, when copper-tin alloy surpasses about 3 area % mutually, and since the expansion of copper in sintering, the dimensional stability during with the infringement sintering, and therefore, it is 1～3 area % that the blending ratio in the raw material powder preferably is adjusted to the area of copper-tin alloy on section.Copper-tin alloy mutually can be by being that raw material powder forms with independent copper powder and independent tin powder, and still like this, it is very big to be fluctuateed by the composition in its copper-tin alloy that forms and the meeting that distributes, the dimensional stability and the abrasion resistance properties of infringement sintered alloy.Therefore, preferably use copper-tin alloy.Copper-tin alloy in being scattered in pearlite matrix is with tiny shape, for example largest grain size is smaller or equal to 20 μ m, and account for 80 area % of total copper-tin alloy phase and when above, the dispersion homogeneity of copper-tin alloy phase improves, from the consistency angle with also more effective.When preparation compacts blank, because the bridging state of powder particle, copper-tin alloy powder may keep not disperse state, may form the copper-tin alloy phase of grain-size more than or equal to 150 μ m by the copper-tin alloy powder that does not spread.If such copper-tin alloy accounts for the ratio of whole copper-tin alloy phase on section be 5 area % or still less, such amount is an acceptable.Copper in the sintering-tin alloy powder forms liquid phase, will help to quicken sintering, and correspondingly, copper and tin are dissolved in matrix and strengthen matrix with soluble solids.But the copper of excessive solid solution is because its expansion causes dimensional stability sharply to descend, and the tin of excessive solid solution makes matrix produce fragility.In order to prevent the above-described problem from occurring and to make the dispersion of appropriateness mutually of copper-tin alloy, in copper-tin alloy powder of using, the content of tin is preferably in 8～11 quality %.As a result, the composition of copper in the sintered alloy-tin alloy phase very approaching above-mentioned scope that also becomes.So according to the composition and the area ratio of copper-tin alloy on section of copper-tin alloy powder, the definite suitable copper and the content of tin account for 3.5～5 quality % and 0.3～0.6 quality % of total alloy composition respectively.

It is then even more ideal mutually to add the little metal oxide compound in pearlite matrix, but optional.The oxide compound of at least a metal of selecting in the cohort that metal oxide is made up of aluminium, silicon, manganese, iron, titanium and calcium is mutually formed, and oxide compound improves machinability as the component that is easy to cut.But excessive oxide compound will cause the fragility of matrix, and preferably the amount of oxide compound accounts for 0.46～1.41 quality % of total composition, is scattered in the pearlite matrix.The homogeneous dispersing metal oxides is crucial mutually in matrix, can use the iron powder that contains metal oxide as raw material powder.Metal oxide in the iron powder preferably accounts for 0.5～1.5 weight % of total amount, comprises the mineral reduction iron powder in such iron powder.The metal oxide that atomized iron powder commonly used and iron scale reduced iron powder contain is less.

In addition, be dispersed with the free graphite phase in the metallographic structure.It improves the machinability and the wearability of sintered alloy from the powdered graphite of raw material with the form of solid lubricant.Although because of it loses in specimen preparation, metallographic section by alloy is difficult to accurately determine the ratio of free graphite in sintered alloy, according to JIS-G1211 " analytical procedure of carbon content ", the method of quantitatively definite uncombined carbon can be determined the mass ratio of free graphite, according to the content of graphite that as above obtains and the proportion of graphite, the relation between the ratio that can obtain the free graphite phase and the free graphite effect mutually.According to above-mentioned,,, will cause rigid cementite (FeC if the amount of the free graphite that contains in the sintered alloy that forms surpasses 3.2 area % when free graphite is approximately 0.8 area % or when higher, its effect is more remarkable mutually ₃) in matrix, separate out, thereby reduce machinability.Excessive powdered graphite also can damage the compactibility of powder, reduces the ratio of matrix in sintered alloy, reduces the intensity of sintered alloy.Therefore, the ratio of free graphite phase, preferably the section with respect to alloy is more than or equal to 0.8 area %, smaller or equal to 3.2 area %.

In order further to improve machinability, at least a solid lubricant that is used as in the mineral dust of manganese sulfide (MnS) powder and Magnesium Silicate q-agent mixes, ratio in raw material powder is smaller or equal to 1.6 quality %, and it will be dispersed in the pore of sintered alloy or the crystal boundary of powder.MnS improves wearability mutually with Magnesium Silicate q-agent mutually, and is effective especially to improving machinability.In addition, MnS protects the blade of cutting tool mutually and prolongs life-span of instrument; The Magnesium Silicate q-agent mineral have the property of riving, and make cutting easily in cutting, can effectively reduce cutting force.These two kinds of compositions have the effect of fragment rimose, effective proactive tool cutting edge is heated, thereby prolongs life tools by fragment is rived.

The metallographic structure of above-mentioned sintered alloy has free graphite phase, iron-phosphorus-carbon compound phase, copper-tin alloy phase, metal oxide phase and solid lubricant phase as required, such sintered alloy can be made by the following method, be used for making sintered valve guide then, as long as the compacts forming step is set, just can obtain having the sintered valve guide of desired shape in the manufacturing of sintered alloy.The result is that the sintered alloy of formation and sintered valve guide have following composition, copper: 3.5～5 quality %, tin: 0.3～0.6 quality %, phosphorus: 0.04～0.15 quality %, carbon: 1.5～2.5 quality %, metal oxide: 0.46～1.41 quality %, and the iron of surplus.The amount of solid lubricant, if desired, then smaller or equal to 1 quality % of the total composition of alloy.

The density that general valve is led is 6.3～6.9g/cm ³, and comprise by density than about 4～15% the pore that calculates.Above-mentioned according to sintered valve guide of the present invention in this too.

Make sintered alloy and sintered valve guide, at first will prepare powdered mixture.Raw material comprises, powdered graphite, iron-phosphorus alloy powder, copper-tin alloy powder, iron powder, and solid lubricant powder as required with these powder uniform mixing, form powdered mixture.Below will describe in detail this raw material powder.

Form the raw material iron powder of pearlite matrix, atomized iron powder for example, the size of particle is approximately-150 to-65 orders (by 65～150 purpose sieves, be 104～200 μ ms to particle diameter).Perhaps use the mineral reduction iron powder, its size of particles is-150 to-65 orders, and contains aforesaid metal oxide, and the amount of total oxide compound is 0.5～1.5 quality %, and oxide compound can improve machinability.The mineral reduction oxide compound contains the metal oxide of high level, and this is to be brought by its previous preparation method, and metal oxide can effectively improve machinability.The content of metal oxide is lower than above-mentioned scope, with the improvement that reduces machinability.The content of metal oxide is higher than above-mentioned scope, will cause sclerosis, and the compressibility of infringement powder, thereby is undesirable.The mineral reduction iron powder is porous, can be absorbed in the copper-tin alloy of the liquid phase that forms in the sintering process because of wicking action, and this makes that the composition profiles in the sintered alloy is more even.The big mineral reduction iron powder of grain-size is difficult to improve the density of powder, and the flowable of the little reduction powder of grain-size, therefore, size is approximately-150 more suitable to-65 purpose powder.But the mineral reduction iron powder contains more metal oxide, and is hard slightly than atomized iron powder and so on, and compressibility is poor slightly, so the intensity of the sintered valve guide that obtains is by will hanging down a bit slightly that atomized iron powder makes.Like this, can be according to characteristic to sintered valve guide, intensity or machinability are selected the raw material iron powder.Perhaps, use the mixed mixture of mineral reduction iron powder and atomized iron powder, for example, contain the atomized iron powder of 10 quality % or more in the mixed powder, improve the compressibility of powder and the intensity of gained sintered alloy.In this case, if the alternative ratio of atomized iron powder greater than 30 quality %, may cause the irregular distribution of metal oxide, suppressed the improvement of machinability.So when mixed mineral reductibility iron powder and atomized iron powder, alternative ratio is preferably 10～30 quality %.The size of particles that atomizing iron divides is identical or slightly little with the mineral reduction iron powder.

Iron-phosphorus alloy powder is the material that is used to provide phosphorus, and using it mainly is angle from safety control, because phosphorus is very unstable and inflammable.Phosphorous diffusion enters the matrix of iron, by forming intensity and the abrasion resistance properties that iron-phosphorus-carbon compound improves the pearlite matrix metal mutually.When the phosphorus content in iron-phosphorus alloy is approximately 10～13 quality %, can form the liquid phase of iron-phosphorus alloy 950～1050 ℃ of scopes.A large amount of liquid phases is undesirable, because can damage size stability in sintering, but the liquid phase of appropriate amount promotes the growth of constriction, improves the intensity of sintered alloy.So to be preferably be 15 quality % or more to phosphorus content in iron-phosphorus alloy powder, be used for the amount of the liquid phase that appropriateness control produces.Be diffused in sintering in the iron more than or equal to the phosphorus in iron-phosphorus alloy of 15 quality % at phosphorus content, when the concentration of the phosphorus of some position reached above-mentioned scope, powdered alloy will produce liquid phase.Liquid phase has wet the surface of iron powder, and phosphorus then enters iron powder by liquid phase fast, has reduced that the concentration of phosphorus is lower than above-mentioned scope in the liquid phase, and liquid phase is solidified.So iron-phosphorus alloy improves intensity by the growth that promotes the constriction between iron particle, and the generation by the part limits liquid phase and liquid phase is solidified prevent to damage to heavens dimensional stability.If in the iron-phosphorus alloy powder that uses phosphorus content be lower than 15 quality %, the composition of iron-phosphorus alloy reaches above-mentioned scope, in sintering, produce liquid phase because of phosphorous diffusion, make liquid phase ground form more fierce, cause the dimensional stability deterioration, with the reduction of the iron-phosphorus that produces to whole substrate because of phosphorous diffusion-carbon compound amount mutually.On the other hand, the phosphorus content in the iron-phosphorus alloy powder that uses is higher than 21 quality %, iron-phosphorus alloy phase hardening, and the compressibility of powdered mixture reduces, and makes the density of compacts blank and sintered alloy reduce, and causes the strength degradation of the sintered valve guide of gained.In addition, the iron-phosphorus of generation-carbon compound thickening reduces the machinability of sintered alloy, and therefore, the content of phosphorus is 15～21 quality % in preferential iron-phosphorus alloy of selecting, is approximately 0.27～0.7 quality % corresponding to the amount of total powder.From the compressibility of powder, the size of particles of the powder of the iron-phosphorus alloy of use is preferably approximately-250 to-150 orders (maximum size of particles: 61～104 μ m).Iron-phosphorus alloy powder can contain a certain amount of impurity inevitably, for example carbon, silicon, manganese and other, and total impurity level is less than and equals 1.5 quality %.

Copper-tin alloy powder is used for reducing size and increases the distributing homogeneity of copper-tin alloy at sintered alloy, and its size of particles is preferably less than iron powder.The deterioration of the dimensional stability that produces for the expansion that prevents because of copper, embrittlement with the matrix that causes because of the transition solid solution of tin, the content of tin is preferably in 8～11 quality % in copper-tin alloy powder of using, the amount of using preferably is approximately 3.93～5.44 quality % with respect to the integrated powder mixture.From the above mentioned, copper content and tin content are respectively 3.5～5.0 quality % and 0.3～0.6 quality % in the powdered mixture.The size of particles of copper-tin alloy powder is preferably less than iron powder, makes copper-tin alloy powder homodisperse in powdered mixture, and makes the trickle copper-tin alloy that forms to be distributed in the sintered alloy equably mutually.35～61 μ m) then even more ideal if the particle diameter of copper-tin alloy powder of using is-250400 orders (maximum size of particles:.Also inevitably there is a certain amount of impurity in copper-tin alloy powder.

Powdered graphite by engaging with iron powder and iron-phosphorus alloy, has formed pearlitic structure and has produced iron-phosphorus-carbon compound in sintering, and residual graphite forms the free graphite phase.The carbon content that is fit in the sintered alloy is 1.5～2.5 quality %, but consider the consumption of metal oxide in reduced iron powder and the loss that causes with the reaction of water in the ambiance, the amount of powdered graphite is preferably 1.7～2.7 quality % of total powdered mixture.Separate out in pearlite matrix but excessive carbon can cause cementite, and reduce the compactibility of powdered mixture, thereby cause the decline of the density of compacts blank and sintered alloy, and the decline of the intensity of sintered valve guide.If the particle size of the powdered graphite that uses is extremely trickle, free graphite residual behind sintering just becomes very rare mutually; If the particle size of powdered graphite is very big, the compactibility step-down of powdered mixture then, the distribution of each composition in the sintered alloy irregular that becomes, tendency forms ferritic phase around iron-phosphorus-carbon mixture phase.

As mentioned above, the solid lubricant that uses for example can be as MnS and/or Magnesium Silicate q-agent mineral dust, Magnesium Silicate q-agent mineral, Magnesium Silicate q-agent mineral and positive Magnesium Silicate q-agent mineral.Typical Magnesium Silicate q-agent mineral comprise protobastite, clinoenstatite, orthorhombic pyroxene, hypersthene etc., and typical positive Magnesium Silicate q-agent mineral comprise forsterite, chrysolite etc.When using with solid lubricant, in order to prevent that the intensity of sintered alloy is had infringement, its content is preferably 1 quality % of total powdered mixture or still less.

Powdered mixture by above-mentioned raw materials powder uniform mixing forms forms the compacts blank through the shaping dies compression.The mould that uses in the compression has and the corresponding shape of the shape of desired product, and for preparing the mould that valve is led, it has oval tubular intracavity.Particularly, the mould that uses is made up of following: the punch die with hole of oval tubular, with punch die constitute the inner chamber of oval tubular and be positioned at above-mentioned punch die inner chamber the center cylindric core bar and have circular cylindrical cross-section, be positioned at the upper and lower drift of inner chamber.Lower punch is placed inner chamber, powdered mixture is filled in inner chamber, then upper punch is placed on the powder, compress the powder between upper and lower drift more in the axial direction, make the compacts blank therefrom.At this moment, compression pressure preferably be adjusted to make compacts shaping density be about 6.5～7.1g/cm ³

After the above-mentioned shaping, because compacts is long in the axial direction, perhaps compression pressure does not reach the middle portion at axial direction due, cause the compacts blank in the compacted density of axial middle portion less than two ends.Like this, the intensity of the sintered valve guide of gained can die down at axial region intermediate.In order to overcome such problem, in the circumferential surface of the inwall of the inner chamber of punch die and core bar, have at least one will tilt slightly again with respect to the drift travel direction.If this pitch angle is very little, influence to the size of compacts blank can be remedied by the elasticity rebound effect of powder particle, product size is not being produced under the prerequisite of substantial effect, make compression pressure arrive axial middle portion, can obtain the compacts blank of density homogeneous like this.Rake ratio if it less than 1/5000, is not enough to improve the compacted density of middle portion, greater than 1/1000, can make that then the diameter of middle portion is obviously different with the two ends of compacts blank being greatly desirable about 1/5000～1/1000 o'clock.

By the compacts blank of die forming, in non-oxidizing atmosphere, carry out sintering and cooling at 950～1050 ℃.In the said temperature scope, graphite and iron powder reaction form pearlitic structure.Also have, a part of iron-phosphorus alloy becomes liquid phase, and it is strong to promote to form sintering by the diffusion between powder, and simultaneously, phosphorous diffusion with the graphite reaction, forms iron-phosphorus-carbon compound phase, and forms separating out of iron-phosphorus-carbon compound phase in the cooling behind sintering in iron powder.Copper-tin alloy becomes liquid phase in agglomerating heat-processed, quickens sintering and promotes copper and tin to be diffused in the iron-based body.Sintering and cooled sintered alloy comprise, in perlite disperse with separate out, with the iron-phosphorus-carbon compound of film like mutually, with disperse with the trickle copper-tin alloy of from liquefaction copper and tin, separating out mutually.Metallographic structure formed in 5 minutes greatly, but the prolongation sintering time improves the intensity of sintered products by further growth constriction between ferrous powder granules, therefore, sintering time is more preferably greater than equaling 20 minutes, and is then even more ideal more than or equal to 45 minutes from the angle of intensity.But carry out sintering in the sintering temperature that is higher than 1050 ℃, perhaps sintering time can quicken graphite diffusion and enter in the matrix above 90 minutes, thereby reduced the amount of residual free graphite, increase iron-phosphorus-carbon compound phase of separating out, also improved the thickness of iron-phosphorus-carbon compound phase.Thereby cause the rapid decline of machinability.On the other hand, if sintering temperature is lower than 950 ℃, sintering process is carried out insufficiently, form undesirable metallographic structure, and intensity reduces significantly.Because the formation speed of liquid phase changes with Heating temperature in sintering, so the best short period of time sintering at high temperature of compacts blank, perhaps long-time at low temperatures sintering is to obtain required metallographic structure.Since at a slow speed cooling can cause that the amount of iron-phosphorus-carbon compound phase increases, the separating out and the increase of thickness of ferritic phase, so speed of cooling is even more ideal greater than 10 ℃/minute more preferably greater than equaling 8 ℃/minute.

According to as above sintering, obtain the sintered valve guide blank, next carry out the high-accuracy mechanical processing of internal surface by reamer, form final sintered valve guide.The present invention has realized improving the machinability of the sintered alloy that is used for sintered valve guide, thereby has shortened mechanical workout institute time-consuming, has reduced manufacturing deficiency.

The blank of sintered valve guide is immersed in the oil, make by wicking action and will effectively improve the resistance to air loss of sintered valve guide by adsorbed oil in the pore.Oil can also play the effect of lubricating oil in mechanical workout, can improve machinability.When immersion oil, can force to make oil to penetrate in the blank of sintered valve guide by vacuum outgas.In addition, adding similar molybdenumdisulphide etc. in oil helps and improves machinability and wear-resistant property.

According to the section of the metallographic structure of the sintered valve guide of the present invention that obtains as mentioned above as shown in Figure 1.Metallographic structure comprises by matrix, pore P, is scattered in the graphite phase G of pore P, and matrix itself comprises perlite phase PE, the copper-tin alloy phase CS that may contain metal oxide MO and iron-phosphorus-carbon compound FPC mutually.Iron-phosphorus-carbon compound phase FPC is very thin, is surrounded by very small amount of ferrite F.

What Fig. 2 showed is the sectional schematic diagram of the metallographic structure of described conventional sintering alloy, for example the sintered alloy of the high content of phosphorus in the public clear 55-34858 communique of spy.Wherein, it is more more than or equal to the part of thick iron-phosphorus-carbon compound phase of 15 μ m to have thickness, owing to the not enough ferritic amount that forms of carbon also than higher, surround iron-phosphorus-carbon compound phase.Sintered alloy with such metallographic structure is compared with the sintered alloy with metallographic structure as shown in Figure 1, and machinability and intensity are all poor.That is to say that the sintered alloy in the special public clear 55-34858 communique has thick iron-phosphorus-carbon compound phase as shown in Figure 2.

Embodiment

Below with reference to embodiment the present invention is described in detail.

Embodiment 1

Sample 1～27

With mineral reduction iron powder (containing metal oxide compound 0.1 quality %) or atomized iron powder (containing metal oxide compound 0.2 quality %) as the raw material iron powder, according to the described blending ratio of table 1, raw material iron powder and iron-phosphorus alloy powder, copper-tin alloy powder and powdered graphite are mixed, prepare the powdered mixture of sample 1～27 respectively.The integral body of each powder mixes matter sample is formed as shown in table 2.The particle diameter of various powder is as follows respectively: the mineral reduction iron powder is (more than or equal to 150 μ m:5%, 45～150 μ m:75%, less than 45 μ m:20%), atomized iron powder is (more than or equal to 150 μ m:17%, 45～150 μ m:58%, less than 45 μ m:25%), iron-phosphorus alloy powder is (more than or equal to 63 μ m:3%, 45～63 μ m:10%, less than 45 μ m:87%), and copper-tin alloy powder (more than or equal to 150 μ m:7%, 45～150 μ m:73%, less than 45 μ m:20%), powdered graphite (median size: 0.6～0.8mm).

Each powder mixes matter sample is suppressed under 550MPa pressure, form pipe shape compacts green compact (being used for wearing test and machinability test), its external diameter is 11mm, internal diameter is 6mm, length is 40mm, and ring-type compacts green compact (being used for radially crushing test), and its external diameter is 18mm, internal diameter 10 is mm, and length is 10mm.Two kinds of compacts green compact temperature in non-oxidizing atmosphere is 1000 ℃ of sintering 60 minutes, is cooled to 600 ℃ with 12 ℃/minute speed from 1000 ℃, is cooled to room temperature then, obtains sintered compact sample 1～27.

The section of the metal structure of each sintered compact is by microscopic examination (* 340), measure iron-phosphorus-carbon compound phase, the copper-tin alloy ratio (area %) in metallographic structure respectively, the ratio (area %) of ferritic phase in matrix, the ratio of free graphite (quality %), and the thickness of iron-phosphorus-carbon compound in mutually less than 5 μ m, more than or equal to 5 μ m smaller or equal to 15 μ m, greater than the ratio separately (area %) of 15 μ m.The result is as shown in table 3.

In addition, each sintered compact sample 1～27 is carried out wearing test, machinability test and crushing test radially respectively, to determine abrasion loss, the machinability exponential sum radial crushing strength constant of each sample.The result is as shown in table 3.

Wearing test: the wearing test of each tubular body is to lead on the wear testing machine at vertical valve to carry out.In the wearing test, the bottom of valve rod and piston links, and is vertical direction with the axis of piston, and valve is inserted in the sintered compact, moves forward and backward 500 ℃ of transverse loads that apply 3MPa under atmosphere of exhaust.The speed of stroke is 3000rmp, and length of stroke is 8mm.After the to-and-fro movement after having carried out 30 hours, measure the abrasion loss (μ m) of the inner peripheral surface of sintered compact.

Machinability test: use the sintered hard alloy reamer, the inner peripheral surface of tubular body is cut, time necessary when measuring the cutting sintered compact and reaching the degree of depth of axial 10mm.With the needed time of sample 13 (composition is equivalent to the alloy in the special public clear 55-034858 communique, hereinafter is called conventional alloys) be 100, correspondingly the needed time of each sample is converted into index value.Wherein, the low more sintered compact that shows of index is easy to cutting, and the used time is short, and promptly cutting ability is outstanding.

Crushing test radially:, ring-shaped sintered body radially applying increased pressure gradually, is broken up to sintered compact according to JIS Z2507 " sintered bearing-radial crushing strength measuring method ".Radial crushing strength constant K (N/mm ²) calculate (wherein, F is the peak pressure load (N) of sintered compact when breaking, and L is ring-shaped sintered body length (mm), and D is the external diameter (mm) of ring-shaped sintered body, and e is the wall thickness (mm) of ring-shaped sintered body) by above-mentioned peak pressure load by following formula (1).

K＝F(D-e)/(L×e ²)(1)

The relative integrally combined thing of phosphorus content in the sample 1～9 changes, and the content of phosphorus in iron-phosphorus alloy powder is fixed in the sample 1～7, and phosphorus content all changes with respect to whole compositions and iron-phosphorus alloy powder in the sample 8 and 9.Fig. 3 A-3D has shown with respect to the relation between the ratio of relevant each phase of the phosphorus content of total composition and these samples and sample 10 (the disclosed sintered alloy in the special public clear 55-034853 communique is called conventional alloys later on).Phosphorus content and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Fig. 4 A-4D.

Shown in Fig. 3 A, 3C, 3D and Fig. 4 A, the increase of phosphorus content changes little (Fig. 3 B) to the ratio of copper-tin alloy phase, still, the thickness of iron-phosphorus-carbon compound phase increases and sharply increases with phosphorus content, during greater than 0.15 quality %, the free graphite amount reduces at phosphorus content, and ferritic amount increases.These results show that the formation of iron-phosphorus-carbon compound phase has been quickened in the increase of phosphorus content, but form the carbon that iron-phosphorus-carbon compound will consume free graphite mutually and be dissolved in matrix, have correspondingly increased ferritic amount.In addition, as Fig. 4 B, Fig. 4 C, Fig. 4 D, phosphorus content has outstanding machinability less than the sintered compact of 0.04 quality %, but abrasion loss is big, the radial crushing strength constant is little.When phosphorus content more than or equal to 0.04 quality %, along with phosphorus content increases, radial crushing strength increases and abrasion loss descends the machinability index decreased.Particularly, phosphorus content is more than or equal to 0.15 quality %, and the machinability index significantly improves.

Shown in Fig. 3 D, 4A, 4C, machinability exponential fluctuation obviously ratio and the thickness with the iron-phosphorus-carbon compound phase that forms is relevant more than or equal to the ratio of 15 μ m.When phosphorus content more than or equal to 0.15 quality %, iron-phosphorus-carbon compound mutually in thickness be smaller or equal to 10 area % more than or equal to the ratio of 15 μ m, the machinability index is smaller or equal to 35, that is, iron-phosphorus-carbon compound phase trickle or that reduce size can be improved machinability.

On the other hand, the fluctuation of radial crushing strength is relevant with the ratio of iron-phosphorus-carbon compound phase.Increase along with the ratio of iron-phosphorus-carbon compound phase, the radial crushing strength index raises, at phosphorus content during more than or equal to 0.04 quality %, the radial crushing strength constant of sintered compact has the sufficiently high value more than or equal to 500MPa, and iron-phosphorus-carbon compound becomes mutually smaller or equal to 0.1 area %, and phosphorus content is during more than or equal to 0.1 quality %, and the radial crushing strength constant is higher than conventional alloys.But the ferritic ratio that intensity is low also increases along with the growth of phosphorus content, so phosphorus content will cause strength deterioration more than or equal to 0.2 quality %.

The fluctuation of abrasion loss is relevant with the ratio of iron-phosphorus-carbon compound phase, and when phosphorus content was 0.1 area % more than or equal to 0.04 quality % with iron-phosphorus-carbon compound ratio mutually, the abrasion loss of sintered compact sharply descended.That is, abrasion loss descends along with the increase of iron-phosphorus-carbon compound ratio mutually of phosphorus content and formation.

The above results shows, when the phosphorus content of all relatively compositions is 0.04～0.15 quality %, the ratio of iron-phosphorus-carbon compound phase is 0.1～3 area %, the ratio that thickness accounts for total iron-phosphorus-carbon compound phase more than or equal to the area of 15 μ m iron-phosphorus-carbon compound phases can obtain to lead at the suitable valve of radial crushing strength, machinability and abrasion resistance properties during smaller or equal to 10 area %.

In sample 4 and 11～23, tin content and/or copper content change with respect to the integrally combined thing.Particularly, for fixing, the composition of copper-tin alloy powder is consistent to copper content in sample 4 and sample 15～19 in sample 4 and sample 11～14, and the ratio of the composition of tin and copper in total composition changes in sample 20～23.For these samples and sample 13, the relation in total composition between tin content and each ratio mutually is referring to Fig. 5 A-5D.Tin content and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Fig. 6 A-6D.In addition, the relation between copper content and each ratio mutually is referring to Fig. 7 A-7D, and copper content and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Fig. 8 A-8D.

Among Fig. 5 B, the variation of the composition of copper-tin alloy phase sharply changes along with the addition manner of tin, as if shown in this result and Fig. 7 B, the ratio of copper-Xi phase more depends on copper content rather than tin content.In addition, Fig. 5 A, Fig. 5 C, Fig. 5 D and Fig. 6 A show that also tin content is also less to the influence of each phase morphology in the metallographic structure.

On the contrary, along with the increase of tin content, abrasion resistance properties and radial crushing strength raise and the machinability reduction.When the relative integrally combined thing of tin content during more than or equal to 0.3 quality %, sintered compact shows suitable wear-resistant property and radial crushing strength, and for example abrasion loss is that radial crushing strength is more than or equal to 500MPa smaller or equal to 70 μ m.Consider machinability, tin content is preferably smaller or equal to 0.6 quality %.

According to Fig. 7 A and Fig. 8 A, the increase of copper content can cause the iron-phosphorus-ratio of carbon compound phase and the decline of thickness, thereby has improved machinability shown in Fig. 8 C.At this moment because copper has promoted the hardenability of matrix and has accelerated apparent speed of cooling (will describe in detail in the back by the influence of speed of cooling).Also have, Fig. 7 B shows increases the ratio that copper content can improve copper-tin alloy phase.The existence of copper-tin alloy phase, himself is softer, compactibility is outstanding, can improve abrasion resistance properties and be easy to processing, so copper content during more than or equal to 3.5 quality % sintered compact show suitable machinability index (Fig. 8 C) more than or equal to 35.In addition, copper-tin alloy also can improve radial crushing strength (Fig. 8 D), but, more than or equal to 5 quality % the time, can reduce intensity, because copper-tin alloy self is soft excessively.According to The above results, the optimum range of tin content is 0.3～0.6 quality %, and the scope of copper is 3.5～5.0 quality %.

At sample 4 and sample 24～27, changed the content of carbon with respect to the integrally combined thing.In these samples and the sample 13, with respect to the relation between the carbon content of integrally combined thing and corresponding each ratio mutually referring to Fig. 9 A-9D, and carbon content and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 10 A-10D.

By Fig. 9 A and Figure 10 A as can be known, along with carbon content increases, the ratio of iron-phosphorus-carbon compound phase and thickness increase, and the amount of free graphite also increases (Fig. 9 C).But when Fig. 9 D was presented at carbon content and is higher than 2.5 quality %, ferritic amount sharply increased, and shows the generation along with iron-phosphorus-carbon compound phase, is accompanied by the disengaging of carbon from matrix.

Machinability index among Figure 10 C is subjected to the influence of the thickness of iron-phosphorus-carbon compound phase, also is subjected to the influence of free graphite phase ratio.In carbon content is the scope of 1.5～2.5 quality %, the machinability index is minimum, and be accompanied by because of having increased the machinability exponential that free graphite produces and reduce (machinability raisings), and because of the increase and the growth machinability exponential raising (deterioration of machinability) of iron-phosphorus-carbon compound phase.As for abrasion loss, can think and reduce along with the increase of iron-phosphorus-carbon compound phase.But although prediction radial crushing strength index will improve along with the increase of iron-phosphorus-carbon compound phase, in fact, shown in Figure 10 D, the radial crushing strength index reduces, particularly in carbon content during greater than 2.5 quality %.At this moment because the increase of carbon powder content can cause the compactibility deterioration of powdered mixture, thereby is lowered into the intensity of body blank and sintered compact.According to The above results, consider that from the angle of radial crushing strength, machinability and abrasion resistance properties optimal carbon content is 1.5～2.5 quality %.

Embodiment 2

Sample 28～38

The powdered mixture of sample 4 same compositions of use and embodiment 1, by preparing sintered compact sample 28～31 with sample 4 similar operation (prepare powdered mixture, manufacture body blank, sintering and cooling), wherein sintering temperature changes to some extent, as shown in table 4, be respectively 900 ℃ (samples 28), 950 ℃ (sample 29), 1050 ℃ (sample 30), 1100 ℃ (sample 31).The integral body of the powdered mixture of each sample is formed as shown in table 5.

Also have, by preparing sintered compact sample 32～36 with sample 4 similar operation (preparation mix powder, manufacture body blank, sintering and cooling), but sintering time is changed into 10 minutes (sample 32), 20 minutes (sample 33), 45 minutes (sample 34), 90 minutes (sample 35) and 120 minutes (sample 36).

In addition by preparing sintered compact sample 37 and 38 with sample 4 similar operation (preparation mix powder, manufacture body blank, sintering and cooling), but the speed of cooling behind the sintering is changed into 8 ℃/minute (samples 37) and 4 ℃/minute (sample 38).

Use each sintered compact sample 28～38,,, measure corresponding each corresponding proportion on the metallographic structure section of sintered compact according to the identical method of above-mentioned and sample 1～27 by observation to section, and wear and tear, machinability and radial crushing strength test.The result is as shown in table 6.

Table 4

Table 5

For the relation of the sintering temperature of sample 4 and sample 28～31 and corresponding each ratio in the integral body composition shown in Figure 11 A-11D, and sintering temperature with iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 12 A-12D.

According to Figure 11 B, the ratio of copper-tin alloy phase and sintering temperature are irrelevant.On the other hand, when sintering temperature is higher than 900 ℃, form iron-phosphorus-carbon alloy phase, its ratio and thickness increase (Figure 11 A and 12A) with the rising of sintering temperature, and in contrast, the amount of free graphite reduces (Figure 11 C).This is that the dissolving and the diffusion process of graphite accelerate, and form a high proportion of ferrite in lower sintering temperature because under higher sintering temperature, and this is because the diffusion difficulty of graphite grains.But ferritic ratio increases when being higher than 1100 ℃, causes the deficiency (Figure 11 D) of carbon because excessively formed iron-phosphorus-carbon compound phase.

From Figure 11 A-11D and Figure 12 A-12D as can be seen, there is definite relation between the thickness of machinability exponential sum iron-phosphorus-carbon compound phase and the ratio of free graphite phase.During smaller or equal to 1050 ℃, the machinability index is smaller or equal to 35 in sintering temperature, and the ratio of iron-phosphorus-carbon compound phase is about smaller or equal to 3 area %, and thickness more than or equal to the ratio of iron-phosphorus-carbon compound phase of 15 μ m smaller or equal to 10 area %.

As for radial crushing strength, not only the ratio with iron-phosphorus-carbon compound phase is relevant, and relevant with the ratio of ferritic phase, and the ferritic phase ratio is when higher, and radial crushing strength descends.When sintering temperature was in 950～1050 ℃ of scopes, radial crushing strength was more than or equal to 500MPa, and the ratio of iron-phosphorus-carbon compound phase of this moment is 0.2～3 area %, and ferritic phase is smaller or equal to 9 area %.

As mentioned above, although composition is identical, it is very remarkable that the metallographic structure of formation and material behavior are influenced by sintering temperature.Resulting sintered valve guide has suitable material behavior in sintering temperature is 950～1050 ℃ of scopes, the ratio of its iron-phosphorus-carbon compound phase is 0.2～3 area %, smaller or equal to 10 area %, and the ratio of ferritic phase is smaller or equal to 9 area % to thickness more than or equal to the ratio of iron-phosphorus-carbon compound phase of 15 μ m.

For sample 4 and 32～36, the relation of sintering time and corresponding each ratio in integral body composition shown in Figure 13 A-13D, sintering time and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 14 A-14D.

Shown in Figure 13 A, 13C and 13D, the solid solution of carbon is carried out along with the prolongation of sintering time with diffusion and the formation mutually of iron-phosphorus-carbon compound, and when the diffusion deficiency of carbon or iron-phosphorus-carbon compound excessively generated mutually, the ratio of ferritic phase increased.The influence of these results and sintering temperature is similar.

So, the ratio of iron-phosphorus-carbon compound phase and thickness and free graphite ratio mutually, with the relation of machinability shown in Figure 13 A-13D and Figure 14 A-14D, sintering time is smaller or equal to 90 minutes scope the time, the machinability index is smaller or equal to 35, and wherein the ratio of iron-phosphorus-carbon compound phase is smaller or equal to 3 area %, and thickness is more than or equal to the ratio of iron-phosphorus-carbon compound phase of 15 μ m 10 area % smaller or equal to total iron-phosphorus-carbon compound phase, and free graphite is more than or equal to 1 area %.

Also have, make that radial crushing strength is more than or equal to 20 minutes more than or equal to the sintering time of 500MPa.Even sintering time smaller or equal to 20 minutes, also can form iron-phosphorus-carbon compound phase, and the amount that forms is enough to represent special intensity, and metallographic structure forms in essence.The increase of the sintered compact intensity that the prolongation sintering time brings is the growth owing to the constriction between the iron particle, and sintering time should be determined according to needed radial crushing strength and abrasion resistance properties.

For sample 4,37 and 38, the relation of speed of cooling and corresponding each ratio in integral body composition shown in Figure 15 A-15D, speed of cooling and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 16 A-16D.

From Figure 15 A-15D and 16A as can be seen, copper-tin alloy does not have any relation with free graphite amount and speed of cooling mutually mutually, but under higher speed of cooling, the amount of iron-phosphorus-carbon compound phase and ferritic amount reduce, thereby the thickness of iron-phosphorus-carbon compound phase also descends.

In material behavior, machinability is subjected to having the greatest impact of speed of cooling change.Usually, along with speed of cooling is accelerated, the precipitate size miniaturization that under higher speed of cooling, is solidified to form by liquid substance.Iron-the phosphorus of separating out in the sintered valve guide-carbon compound phase attenuation, amount also diminishes, and ferritic ratio descends.The result is that the machinability of the sintered compact of formation is improved.Copper-tin alloy phase the precipitate of separating out from liquid phase has also diminished.Make the machinability index smaller or equal to 35 speed of cooling for more than or equal to 8 ℃/minute, this moment, the ratio of iron-phosphorus-carbon compound phase was smaller or equal to 3 area %, thickness is that the ratio of ferritic phase also is less than and equals 5 area % smaller or equal to 10 area % of total iron-phosphorus-carbon compound phase more than or equal to the ratio of iron-phosphorus-carbon compound phase of 15 μ m.

Embodiment 3

Sample 39～49

Sintered compact sample 39～42 is by powdered mixture 4 similar steps (prepare powdered mixture, manufacture body blank, sintering and the cooling) preparation per sample of listed sample in the table 7, but in the raw material iron powder, contain oxide compound, be respectively 0.2 quality % (iron scale reduced iron powder, sample 39), 0.5 quality % (sample 40), 1.5 quality % (sample 41), 2.0 quality % (sample 42).The integral body of the powdered mixture of each sample is formed as shown in table 8.

Prepare sample 43～49 separately, basic identical with the operation (prepare powdered mixture, manufacture body blank, sintering and cooling) of sample 4, except some or all of mineral reduction iron powder is atomized iron powder (oxide content: 0.2 quality %) substitute, and its ratio that accounts for total powdered mixture is 5 quality % (sample 43), 10 quality % (sample 44), 15 quality % (sample 45), 20 quality % (sample 46), 30 quality % (sample 47), 40 quality % (sample 48), 92.2 quality % (sample 49).Use each sintered compact sample 39～49,,, measure corresponding each corresponding proportion on the metallographic structure section of sintered compact, to carry out and wearing and tearing, machinability and radial crushing strength are tested according to the identical method of above-mentioned and sample 1～27 by observation to section.The result is as shown in table 9.

For

sample

4,10 and 39～42, oxide content and the relation of corresponding each ratio in total composition be shown in Figure 17 A-17D in the iron powder, in the iron powder oxide content and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 18 A-18D.

According to Figure 17 A-17D and 18A, oxide content does not almost influence with the formation mutually of copper-tin alloy such as iron-phosphorus-carbon compound mutually for other in the iron powder, and oxide compound separately exists in the metallographic structure.On the other hand, along with oxide content increases, machinability index decreased (Figure 18 C), but simultaneously, radial crushing strength constant and abrasion loss increase (Figure 13 D).So, according to Figure 18 B-18D, make the machinability index smaller or equal to 35, smaller or equal to 360 μ m, the scope of the oxide content in the iron powder is 0.5～1.5 quality % to the radial crushing strength constant more than or equal to 500MPa, abrasion loss.

For

sample

4,10 and 43～49, the relation of the blending ratio of atomized iron powder and corresponding each ratio in total composition shown in Figure 19 A-19D, the blending ratio of atomized iron powder and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 20 A-20D.

In Figure 19 A-19D and 20A, do not observe of the influence of the blending ratio of atomized iron powder to the formation of other phases.In Figure 20 B-20D, very little along with the increase of the blending ratio of atomized iron powder to the performance impact of material, but specifically, the radial crushing strength constant raises, and when all using atomized iron powder, has reached the maximum value of intensity.In addition, the combined amount of atomized iron powder descends, and the machinability index also descends, particularly, and when the addition of atomized iron powder during smaller or equal to 30 quality %, to promoting that machinability is more effective.When using the iron scale reduced iron powder, the machinability index is consistent when using atomized iron powder, but more much better than using the mineral reduction iron powder, and the radial crushing strength constant is a little less than the use atomized iron powder.Therefore, if sintered valve guide needs higher intensity, preferably use atomized iron powder; Better if desired machinability is then preferably used the mineral reduction iron powder.Use if mineral reduction iron powder and atomized iron powder mix, the blending ratio of atomized iron powder is preferably less than and equals 30 quality %, and this moment is more effective to the raising of machinability.

Embodiment 4

Sample 50～66

Composition according to the powdered mixture of each sample as shown in table 10, by preparing sample 50～66 with sample 4 similar operation (prepare mix powder, manufacture body blank, sintering and cooling), wherein add as the magnesium sulfide that improves the machinability composition, content is 0.2～2.0 quality % (sample 50～55 and sample 62～66), perhaps Magnesium Silicate q-agent powder, content is 0.2～2.0 quality % (sample 56～61 and sample 62～66).The relative integrated powder the ingredients of a mixture of each sample is as shown in table 11.

Use each sintered compact sample 55～66,,, measure corresponding each corresponding proportion on the metallographic structure section of sintered compact according to the identical method of above-mentioned and sample 1～27 by observation to section, and wearing and tearing, machinability and radial crushing strength.The result is as shown in table 12.

For

sample

4,10,50～66, corresponding each relation mutually is shown in Figure 21 A-21D in the powder that improves the machinability composition that adds powdered mixture to and whole the composition, the amount that joins the powder that improves the machinability composition in the powdered mixture and iron-phosphorus-carbon compound mutually thickness and the relation of material property (abrasion loss, machinability exponential sum radial crushing strength constant) shown in Figure 22 A-22D.

According to Figure 21 C and 22C, along with the increase of the amount of the powder that improves the machinability composition in powdered mixture, the ratio of free graphite phase increases gradually and the machinability index reduces gradually.But, the effect of improving the machinability composition is gentle relatively, and the reduction gradually with the increase of addition of radial crushing strength constant, when addition surpasses 1.6 quality %, owing to sintering hinders the fragility of the matrix that (diffusion suppresses) cause, make abrasion loss sharply increase.Therefore rely on separately and improve the very difficult machinability of improving significantly of machinability composition powder.Therefore, should be to influencing the factor of machinability, for example the ratio of iron-phosphorus-carbon compound phase and thickness, free graphite ratio mutually etc. are optimized, and are necessary to consider that balance radial crushing strength and abrasion resistance properties are determined composition and processing conditions simultaneously.

It may be noted that the present invention not only limits and above embodiment, also comprises the change that does not break away from claim of the present invention.

Claims

1. sintered valve guide, it is made by sintered alloy, and sintered alloy is made up of 3.5～5% copper, 0.3～0.6% tin, 0.04～0.15% phosphorus, 1.5～2.5% carbon and balance iron, in mass,

Wherein sintered alloy has metallographic structure, and it comprises: by perlite phase, Fe-P-C compound mutually and the graphite of Cu-Sn the alloy phase matrix, the pore that constitute and the disperse that accounts for sintered alloy mass ratio 1.2～1.7% mutually, and

Wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area 10% or below.

2. sintered valve guide, it is made by sintered alloy, and sintered alloy is by 3.5～5% copper, 0.3～0.6% tin, 0.04～0.15% phosphorus, 1.5～2.5% carbon, and 0.46～1.41% metal oxide and balance iron are formed, in mass,

Wherein sintered alloy has metallographic structure, and it comprises: the graphite of matrix, pore that constitutes mutually by perlite phase, Fe-P-C compound phase, Cu-Sn alloy phase and metal oxide and the disperse that accounts for sintered alloy mass ratio 1.2～1.7% mutually,

Wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix alloy area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area 10% or below.

3. sintered valve guide, it is made by sintered alloy, sintered alloy by 3.5～5% copper, 0.3～0.6% tin, 0.04～0.15% phosphorus, 1.5～2.5% carbon, smaller or equal to 1% be selected from solid lubricant at least a in manganese sulfide and the Magnesium Silicate q-agent and balance iron is formed, in mass

Wherein sintered alloy has metallographic structure, it comprises: the matrix, pore, the graphite phase that are made of mutually perlite phase, Fe-P-C compound phase, Cu-Sn alloy phase and metal oxide, and described at least a solid lubricant, this lubricant is distributed in pore or is distributed in the crystal boundary of sintered alloy metallographic structure

Wherein, on the section of the metallographic structure of sintered alloy, perlite account for mutually matrix alloy area 90% or more than, the Fe-P-C compound account for mutually metallographic structure cross-sectional area 0.1～3%, the Cu-Sn alloy phase account for metallographic structure cross-sectional area 1～3%, the graphite that is distributed in pore account for mutually metallographic structure cross-sectional area 0.8～3.2%, have the part of thickness in the Fe-P-C compound more than or equal to 15 μ m, account for total Fe-P-C compound phase area 10% or below.

4. sintered valve guide, it is made by sintered alloy, sintered alloy by 3.5～5% copper, 0.3～0.6% tin, 0.04～0.15% phosphorus, 1.5～2.5% carbon, 0.46～1.41% metal oxide, be less than equal 1.6% be selected from solid lubricant at least a in manganese sulfide and the Magnesium Silicate q-agent and balance iron is formed, in mass

5. sintered valve guide according to claim 2, wherein said metal oxide comprises the oxide compound that is selected from least a metal in aluminium, magnesium, iron, calcium and the tin.

6. sintered valve guide according to claim 1, wherein on the section of metallographic structure, thickness is more than or equal to 5 μ m, account for mutually less than the Fe-P-C compound of 15 μ m total Fe-P-C compound phase area 10～40%, remaining Fe-P-C compound phase thickness is less than 5 μ m.

7. the manufacture method as each described sintered valve guide among the claim 1-4 may further comprise the steps,

The preparation powdered mixture, in mass, it comprises 0.27～0.7% Fe-P powdered alloy, 3.93～5.44% Cu-Sn powdered alloy, 1.7～2.7% powdered graphite and surplus iron powder; Wherein, Fe-P powder powder is made up of the iron of 15～21% phosphorus, unavoidable impurities and surplus; The Cu-Sn powdered alloy is made up of the copper of 8～11% tin, unavoidable impurities and surplus;

Powdered mixture is compressed in tubular intracavity, and powdered mixture forms the tubulose compacts,

With tubulose compacts sintering in non-oxidizing atmosphere, sintering temperature is 950～1050 ℃ then.

8. manufacture method according to claim 7, wherein iron powder comprises and contains the mineral reduction iron powder that accounts for burning amount 0.5～1.5%.

9. manufacture method according to claim 7, wherein iron powder is the mixture of mineral reduction iron powder and atomized iron powder, wherein the content of atomized iron powder is 10～30 quality % in the mixture.

10. manufacture method according to claim 7, wherein the particle diameter of iron powder is-150～-65 orders.

11. manufacture method according to claim 7, wherein the particle diameter of Fe-P powdered alloy is-250～-150 orders, and the particle diameter of Cu-Sn powdered alloy is-250～-400 orders.

12. manufacture method according to claim 7, wherein sintering time is 15～90 minutes.

13. manufacture method according to claim 7 wherein prepares powdered mixture and also further may further comprise the steps:

At least a powder mixes in manganese sulfide and the Magnesium Silicate q-agent mineral is entered in the powdered mixture, and regulating the ratio of described at least a powder in powdered mixture is smaller or equal to 1.6 quality %.

14. manufacture method according to claim 7, wherein tubular intracavity is at the inner circular side face of punch die and constitute in the circumferential surface of a drift of aforementioned tubular intracavity, has one at least with 1/5000～1/1000 rake ratio and tilt.

15. manufacture method according to claim 7 also further comprises, in the sintered compact immersion oil with the sintering gained.

16. manufacture method according to claim 7 also further comprises, with the sintered compact of 8 ℃/minute speed of cooling coolings by the sintering acquisition.