KR101717347B1 - Copper based sintered alloy with wear resistance - Google Patents

Abstract

Wherein the total composition comprises, by mass ratio, 2.0 to 16.0% of Ni, 0.2 to 4.0% of Si, and the balance of Cu and inevitable impurities, the base consisting of pores and a copper or copper-nickel alloy, And the nickel suicide is a wear-resistant sintered copper alloy containing at least 2 mu m in size.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a copper alloy sintered alloy,

The present invention relates to a copper-based sintered alloy excellent in abrasion resistance, and more particularly to a copper-based sintered alloy excellent in thermal conductivity.

BACKGROUND ART A valve guide used in an automotive engine or the like is a component for supporting a shaft portion of a valve and supporting a reciprocating motion of the valve and is required to have a valve reciprocating at a high speed and excellent abrasion resistance for sliding. Conventionally, cast iron and high-strength brass have been used as the material for the valve guide. In recent years, however, iron-based sintered alloys excellent in abrasion resistance (Japanese Patent Publication Nos. 55-034858, 2680927, 4323467, etc.) are widely used.

Japanese Patent Publication No. 55-034858 Japanese Patent No. 2680927 Japanese Patent No. 4323467

Among the environmental awareness increasing year by year, further improvement of the fuel economy of the engine is demanded, and as a method of improving the fuel economy of the engine, the high compression ratio of the engine is examined. That is, the higher the compression ratio is, the more the fuel pressure is increased because the piston is pressed down even if the amount of exhaust gas is equal to the amount of the input fuel. In general, even if the engine of the same series is used, an engine with a high compression ratio has a higher output and a higher torque than an engine with a low compression ratio.

However, the conventional iron-based sintered alloy for valve guides has a low thermal conductivity of about 25 W / (m · K), and has a low ability to dissipate the heat of the valve relative to the slide through the valve guide. Therefore, heat in the beveled portion of the valve exposed to the combustion chamber is difficult to dissipate, heat in the combustion chamber tends to fill up, and knocking tends to occur if the compression ratio for improving fuel economy is increased.

Further, a copper-based alloy (high-strength brass) produced by casting has high thermal conductivity, but has low abrasion resistance, so that it can not be applied to only an engine with a small load.

Therefore, it is possible to increase the thermal conductivity, to have a high ability to dissipate heat from the valve relative to the slide, to prevent knocking even when the compression ratio is increased, and to provide a copper alloy valve A demand for a guide sintered alloy is becoming stronger.

Accordingly, it is an object of the present invention to provide a sintered alloy for a valve guide which has higher thermal conductivity than conventional iron-based sintered alloys and has higher abrasion resistance than conventional high-strength brass.

The present invention is directed to improving the thermal conductivity of a sintered alloy by using a copper-based sintered alloy as a base and improving wear resistance by dispersing hard particles in a matrix of a copper-based sintered alloy.

Specifically, the wear-resistant copper-based sintered alloy of the present invention has a total composition of 2.0 to 16.0% of Ni, 0.2 to 4.0% of Si, and the balance of Cu and inevitable impurities in a mass ratio, Or a copper-nickel alloy, and a granular nickel silicide dispersed in the matrix, and the nickel silicide has a size of 2 탆 or more.

In the above-described abrasion resistant copper-based sintered alloy, it is preferable that nickel silicide having a size of 2 탆 or more is 2% or more in area ratio in the metal structure. It is also preferable that the ratio of Ni to Si in the entire composition is in the range of 0.05 to 0.35 in terms of Ni: 1.

In the abrasion-resistant copper-based sintered alloy, the abrasion resistance can be further improved by further dispersing at least one of iron-based hard phase, cobalt-based hard phase and alloy iron in a total amount of 5.0% by mass or less, By further dispersing 3.0% by mass or less of black toner in the pore as C content in the whole composition, the slide property can be further improved.

The wear-resistant copper-based sintered alloy of the present invention is a copper-based sintered alloy, so that it has excellent thermal conductivity and hard particles are dispersed in the matrix to improve abrasion resistance. When used as a valve guide, A good slide can be maintained and the heat of the valve serving as a slide partner can be dissipated through the valve guide so that the occurrence of knocking can be prevented even if the compression ratio of the engine is increased. And has an excellent effect.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a photograph showing a metal structure of a wear resistant sintered alloy of the present invention.

Cu has a thermal conductivity of 398 W / (m · K) and a thermal conductivity of 4.7 times that of 84 W / (m · K) of Fe. The copper alloy has a lower thermal conductivity than Cu, but exhibits a higher thermal conductivity than Fe and the conventional iron-based sintered alloy (about 25 W / (m · K)). For this reason, in order to improve the thermal conductivity of the sintered alloy, the base is made of copper or a copper alloy.

On the other hand, copper and copper alloys have a low abrasion resistance as compared with Fe and conventional iron-based sintered alloys, and therefore wear resistance is insufficient only by known. Therefore, by dispersing the hard particles in the matrix, the abrasion resistance is improved. The hard particles are preferably uniformly dispersed in the matrix, and preferably precipitated and dispersed in a copper alloy matrix.

From these points of view, the present inventors have found that Ni is suitable as an element to be alloyed with Cu, and that a high thermal conductivity and wear resistance can be secured by using nickel silicide as the hard particles precipitated and dispersed in the matrix. The reasons for limiting the components of the wear-resistant copper-based sintered alloy of the present invention will be described below.

Ni has the function of hiring to Cu, strengthening the base. Further, Ni has an effect of improving abrasion resistance of the copper-based sintered alloy by forming Si and nickel silicide (Ni ₂ Si) described later and precipitating and dispersing in the matrix. If the amount of Ni is less than 2.0 mass%, the above-mentioned effect becomes insufficient and the abrasion resistance of the copper-based sintered alloy becomes low. On the other hand, if the amount of Ni exceeds 16.0 mass%, the amount of Ni dissolved in Cu becomes excessive, and the amount of precipitated nickel silicide becomes excessive, whereby the thermal conductivity of the copper-based sintered alloy becomes remarkable. Therefore, the amount of Ni in the whole composition is 2.0 to 16.0 mass%.

Si is added to improve the wear resistance of the copper-based sintered alloy by forming Ni and nickel silicide (Ni ₂ Si) to precipitate and disperse in the matrix. Since Si has an effect of lowering the liquid phase generation temperature of Cu, sintering is promoted to densify the copper-based sintered alloy, thereby contributing to improvement of the strength of the copper-based sintered alloy. If the amount of Si is less than 0.2 mass%, the amount of nickel suicide to precipitate and disperse becomes insufficient, and the wear resistance of the copper-based sintered alloy becomes low. On the other hand, if the amount of Si exceeds 4.0 mass%, the amount of nickel suicide precipitated and dispersed in the matrix of the copper-based sintered alloy becomes excessive, and the thermal conductivity of the copper-based sintered alloy remarkably decreases. Therefore, the amount of Si in the whole composition is set to 0.2 to 4.0 mass%.

When the amount of Ni is insufficient for Ni or the amount of Ni is insufficient for Si, the amount of nickel suicide precipitated and dispersed is insufficient to lower the abrasion resistance, and at the same time, The amount of Ni or Si increases, and the thermal conductivity of the copper-based sintered alloy decreases. From this viewpoint, it is preferable that the ratio of Ni to Si in the whole composition is set to be Si: 0.05 to 0.35 relative to Ni: 1.

The nickel silicide which precipitates and disperses in the matrix of the copper-based sintered alloy, when it is fine, is plastically flowed to the base at the time of sliding with the valve which is a counter material, and the effect of improving the wear resistance is insufficient. For this reason, the nickel suicide should be in the form of a granule and contain a material having a size of 2 mu m or more. The size of the nickel silicide referred to here is the maximum diameter of one nickel silicide particle. The nickel silicide having a size of 2 mu m or more is preferably 2% or more in terms of the area ratio in the metal structure from the viewpoint of abrasion resistance.

As described above, the wear-resistant copper-based sintered alloy of the present invention is composed of 2.0 to 16.0% of Ni, 0.2 to 4.0% of Si, and Cu and inevitable impurities in the total composition in mass ratio. The metal structure is a metal structure composed of inevitable pores, a base made of copper or a copper-nickel alloy in the production of a sintered alloy, and a nickel metal silicide dispersed in the base and having a grain size of 2 탆 or more .

The porosity is unavoidable in the sintered alloy, but it is preferably as small as possible because it lowers the strength and thermal conductivity of the sintered alloy, and it is preferable that the density of the copper-based sintered alloy is 7.5 Mg / m 3 or more.

The wear-resistant copper-based sintered alloy of the present invention can be produced as follows.

(Si) powder is added to any one of (1) copper powder and nickel powder, (2) copper-nickel alloy powder, and (3) copper powder and copper-nickel alloy powder, 2.0 to 16.0% of Ni, 0.2 to 4.0% of Si, and the balance of cu and unavoidable impurities in the composition ratio by mass.

The raw material powder thus adjusted is molded into a substantially cylindrical valve guide shape at a molding pressure of about 500 to 700 MPa to obtain a valve guide shaped article. Since the copper powder or the copper-nickel alloy powder is relatively soft, it can be set to 7.5 Mg / m < 3 > or more at such a molding pressure.

The obtained formed body is put into a sintering furnace and sintered by heating at a temperature of about 900 to 1050 DEG C in a non-oxidizing atmosphere, and cooled at a normal cooling rate (about 5 to 15 DEG C / minute) Copper-based sintered alloy can be obtained. Here, the nickel suicide is produced and precipitated at the time of cooling the sintering, and is granular and has a size of 2 탆 or more. Therefore, the solution treatment and the aging treatment are unnecessary.

Fig. 1 shows an example of the metal structure of the wear-resistant copper-based sintered alloy of the present invention. The copper-based sintered alloy of Fig. 1 has a total composition of 10% by mass of Ni, 2% by mass of Si and the balance of Cu and inevitable impurities, and the sinter density is 7.8 Mg / m3. In Fig. 1, the light gray portion is a copper alloy base, and the dark gray portion is a nickel silicide particle. In Fig. 1, nickel silicide particles having a maximum diameter of 2 mu m or more in the metal structure are 8 area%. The copper-based sintered alloy of Fig. 1 has a thermal conductivity of 99 W / (mK) and a thermal conductivity of about four times that of a conventional iron-based sintered alloy (about 25 W / (mK)).

The wear-resistant copper-based sintered alloy of the present invention produced by the above is high in thermal conductivity and excellent in abrasion resistance. When it is desired to further improve the abrasion resistance, the iron-based hardness The wear resistance can be further improved by further dispersing at least one of the cobalt-based hard phase and the alloy iron as the second hard phase. However, if the total amount of these hard phases dispersed in the matrix exceeds 5% by mass, the thermal conductivity of the copper-based sintered alloy is markedly lowered. Therefore, the total amount of the hard phases should be 5% by mass or less.

Among the above hard phases, a hard phase in which carbide particles precipitate and disperses in an iron-based alloy base is preferable as the iron hard phase. Specifically, (A) a hard phase consisting of Cr: 4 to 25%, C: 0.25 to 2.4%, and the balance Fe and inevitable impurities in the mass ratio, and the carbide particles of Cr are dispersed in the iron- ) Of at least one of Cr and Cr, 0.25 to 2.4% of Cr, 0.3 to 3.0% of Mo and 0.2 to 2.2% of V, and the balance of Fe and inevitable impurities, Mo: 4 to 8%, V: 0.5 to 3%, W: 4 to 8% by mass, and the hard phase in which the carbide particles of Cr, Mo and V and / or the composite carbide particles of these elements are dispersed in the alloy, V, W, and Cr carbide grains and / or complex carbide grains of these elements in the iron-based alloy, and the balance of Fe and inevitable impurities. Is preferably dispersed.

More specifically, a hard phase in which molybdenum silicide particles are dispersed in an iron-based alloy matrix is preferable. Specifically, (D) 0.5 to 10% of Si, 10 to 50% of Si, and Fe and inevitable impurities 0.5 to 10% of Mo, 10 to 50% of Mo, 0.5 to 10% of Cr, 0.5 to 10% of Ni, and 0.5 to 10% of Mo are contained in the molten steel, and the molybdenum silicide particles are dispersed in the iron- Mn: 0.5 to 5%, and the balance of Fe and inevitable impurities, and the molybdenum silicide particles are dispersed in the iron-based alloy.

As the cobalt-based hard phase, a hard phase in which molybdenum silicide particles are dispersed in a cobalt-based alloy matrix is preferable. Specifically, (F) 1.5 to 3.5% of Si, 7 to 11% of Cr, To 30%, and the balance of Co and inevitable impurities, and the molybdenum silicide particles are dispersed in the cobalt-based alloy.

More specifically, it is preferable to use ferromolybdenum, ferrochrome, and ferro-tungsten as the alloy steel, and more specifically, in the mass ratio of (G), 55 to 65% of Mo, 4% or less of C, (H) a ferrochromic hard phase comprising 50 to 75% of Cr, 1% or less of C, 8% or less of Si, and the balance of Fe and unavoidable impurities at a mass ratio (H) I) a ferro-tungsten hard phase comprising 75 to 85% of W, 0.5% or less of C, 0.5% or less of Si, and the balance of Fe and unavoidable impurities.

These hard phases can be dispersed in the base of the copper-based sintered alloy by adding the powder of the hard phase composition to the raw powder and mixing and performing the above-described molding and sintering.

Further, in the wear resistant copper-based sintered alloy of the present invention, graphite powder of not more than 3.0% by mass can be further dispersed in the pores in the pores by adding 3.0% by mass or less of graphite powder to the raw powder. Graphite has excellent wall properties and acts as a solid lubricant. By dispersing such graphite in the form of graphite in pores, it is possible to further improve the sliding property with the valve which is a counter material.

Example

[First Embodiment]

Nickel alloy powder in which copper powder, nickel powder, silicon powder and an amount of Ni of 20 mass% and the balance of Cu and inevitable impurities were prepared, and the raw powder added and mixed in the ratios shown in Table 1 were mixed at a molding pressure of 600 MPa The obtained molded body was put into a sintering furnace, sintered at a sintering temperature of 1000 占 폚 in a non-oxidizing atmosphere, and cooled at a cooling rate of 12 占 폚 / min. To prepare a copper-based sintered alloy sample of Sample Nos. 01 to 21. Table 1 shows the total composition of these samples.

For comparison, a conventional high-strength brass as a whole was composed of Zn: 40% Zn, Mn: 2%, A1: 1.5%, Si: 0.6%, Pb: 0.6% and the balance Cu and inevitable impurities High-strength brass of the obtained solvent was machined into a cylindrical shape having an outer diameter of 18 mm, an inner diameter of 10 mm and a height of 100 mm as a sample of Sample No. 22.

In addition, iron-phosphorus alloy powder, copper-tin alloy powder and graphite powder were prepared at the end of iron powder as a conventional iron-based sintered alloy for valve guides, and powder having an outer diameter of 18 mm, an inner diameter of 10 mm and a height of 100 mm The resulting compact was sintered at a sintering temperature of 1000 占 폚 in a non-oxidizing atmosphere and cooled at a cooling rate of 12 占 폚 / min to obtain a steel sheet having a total composition of 4.5% Cu, , Sn: 0.5%, P: 0.28%, C: 2.4% and the balance of Fe and inevitable impurities was prepared as a sample of Sample No. 23.

The sintered product density of the copper-based sintered alloy samples of Samples 01 to 21 was measured in accordance with the sintered product density measurement method (underwater weight method) prescribed by JIS Z 2505. The cross section (x 340) of the metal structure of the sintered body was observed using a microscope, and the ratio (area%) of the nickel silicide of 2 탆 or more occupied in the cross section of the metal structure was obtained using QuickGrain Standard manufactured by Innotek Corporation. These results are shown together in Table 1.

Further, for all the samples (sample Nos. 0 to 23), the thermal conductivity was measured, and the abrasion test was carried out to measure the abrasion amount. These results are shown together in Table 1. In the abrasion test, a cylindrical sintered body was attached to a vertical valve guide abrasion tester to perform abrasion test. In the abrasion test, a valve stem was attached to the lower end portion of the piston whose axis was set in the vertical direction, the valve was inserted into the inner diameter of the sintered body, and the valve was reciprocated in an exhaust gas atmosphere at 500 캜 . At this time, the stroke speed was 3000 rpm and the stroke length was 8 mm. After the reciprocating motion for 30 hours, the wear amount (mu m) of the inner circumferential surface of the sintered body was measured.

Further, in evaluating the thermal conductivity, it was evaluated as acceptable that the value of the thermal conductivity of the iron-based sintered alloy sample of the sample No. 23 prepared as the conventional iron-based sintered alloy for valve guides was twice or more. Further, in the evaluation of the amount of wear, it was evaluated as acceptable that the wear amount of the high-strength brass sample of Sample No. 22 prepared as the conventional high-strength brass was 60% or less.

In the copper-based sintered alloy samples of Sample Nos. 01 to 10 of Table 1, the influence of the amount of Ni in the whole composition can be investigated. In the copper-based sintered alloy samples of Samples Nos. 06 and 11 to 20 of Table 1, the influence of the amount of Si in the entire composition can be examined. Further, by comparing the copper-based sintered alloy sample of Sample No. 06 in Table 1 with the copper-based sintered alloy sample of Sample No. 21, the influence of the addition form of Ni can be investigated.

[Influence of Ni amount]

Sample No. 01 does not contain Ni, and nickel silicide (Ni ₂ Si) does not precipitate, and the entire amount of Si is dissolved in the Cu base. For this reason, the amount of wear is as large as 645 mu m. The thermal conductivity is 68 W / (m · K), which is about 2.5 times higher than that of the conventional iron-based sintered alloy sample of Sample No. 23.

Since the sample of the sample No. 02 contains 2 mass% of Ni, Ni is bonded to Si and the nickel suicide (Ni ₂ Si) precipitates and disperses in the matrix. As a result, the abrasion resistance is improved and the wear amount is 352 탆. And is reduced to 57% of the conventional high-strength brass samples. At this time, the nickel silicide having a size of 2 탆 or more occupies 2.1% in the area of the metal structure. In addition, Si precipitates as nickel silicide, and the amount of Si dissolved in the copper alloy base decreases, so that the thermal conductivity also shows a very high thermal conductivity of 121 W (m 占)).

Further, in the samples of Sample Nos. 03 to 10, as the amount of Ni increased, the amount of deposited nickel silicide was increased, and the area ratio of the nickel silicide having a size of 2 탆 or more to the metal structure was increased, Wear resistance is improved. Therefore, the wear amount tends to decrease as the amount of Ni increases.

On the other hand, when the amount of Ni is increased, the amount of nickel silicide precipitated in the matrix increases, so that the proportion of the copper alloy base decreases. For this reason, the thermal conductivity showed a tendency to decrease with increasing amount of Ni, and the sample with sample No. 10 having an amount of Ni of 18 mass% showed a remarkable deterioration in thermal conductivity, and the sample of the conventional sample of iron-based sintered alloy The value is not satisfied.

As described above, it was confirmed that by increasing the Ni content of the abrasion-resistant copper-based sintered alloy to 2.0 to 16.0 mass%, it is possible to improve the thermal conductivity and improve the abrasion resistance (abrasion loss).

[Influence of Si amount]

Sample No. 11 is a sample containing no Si, and nickel silicide (Ni ₂ Si) does not precipitate, and the entire amount of Ni is dissolved in the Cu base. For this reason, the wear amount shows a large value of 534 占 퐉, and the thermal conductivity is 33 W / (m 占 K), which is a value that does not satisfy the double value of the conventional iron-based sintered alloy sample of the sample No. 23.

The sample of the sample No. 12 contains 0.2 mass% of Si, so that the Ni is bonded to Si and the nickel suicide (Ni ₂ Si) precipitates and disperses in the matrix. As a result, the wear resistance is improved and the wear amount is 370 탆. To about 60% of the conventional high-strength brass samples. The area ratio occupied by the nickel silicide having a size of 2 탆 or more in the metal structure at this time is 2.0%. In addition, Ni precipitates as nickel silicide, and Ni dissolved in the copper alloy base decreases, and the thermal conductivity is also improved to 2.2 times that of the conventional iron-based sintered alloy sample of Sample No. 23 at 55 W / (m · K).

In the samples Nos. 13 to 15, 06 and 16 to 20, the amount of nickel silicide precipitated as the amount of Si increases, and the area ratio of the nickel silicide having a size of 2 탆 or more in the metal structure increases, The wear resistance of the sintered alloy is improved. Therefore, the wear amount tends to decrease as the amount of Si increases.

In addition, the thermal conductivity decreases with an increase in the amount of Si up to 3.0 mass%, but decreases with the amount of Si exceeding 3.0 mass%. This is because of the balance between the improvement of the thermal conductivity due to the reduction of the amount of Ni contained in the copper alloy base and the balance of the decrease of the thermal conductivity due to the precipitation of nickel silicide in the copper alloy base. When the amount of Si is 3.0 mass% However, if the amount of Si exceeds 3.0% by mass, the latter influence becomes large and the thermal conductivity is considered to be lowered. For this reason, in the sample of the sample No. 20 in which the amount of Si is more than 4% by mass, the thermal conductivity is remarkably lowered, and the value is not satisfied twice the conventional iron-based sintered alloy sample of the sample No. 23.

As described above, it was confirmed that by increasing the Si content of the wear-resistant copper-based sintered alloy in the range of 0.2 to 4.0 mass%, it is possible to improve the thermal conductivity and improve the abrasion resistance (abrasion loss).

[Effect of addition type of Ni]

The copper-based sintered alloy sample of Sample No. 06 is an example in which Ni is added in the form of nickel powder, and the copper-based sintered alloy sample of Sample No. 21 is an example of Ni in the form of copper-nickel alloy powder. 10% by mass of Ni, 2% by mass of Si and the balance of Cu and inevitable impurities, and only the addition form of Ni is another sample. When these samples are compared, it can be seen that the thermal conductivity and wear amount are almost the same value, and the addition form of Ni is not affected.

[Second Embodiment]

The copper powder, nickel powder and silicon powder used in Example 1 and the hard phase forming powders of the compositions shown in Table 2 (numerical values of the element symbol are expressed in% by mass) were prepared and added in the ratios shown in Table 2 The raw material powders thus mixed were molded and sintered under the same conditions as in Example 1 to prepare samples of copper-based sintered alloys of Sample Nos. 24 to 38. Table 3 shows the total composition of these samples.

These samples were measured for thermal conductivity and abrasion resistance in the same manner as in the first example. The results are also shown in Table 3. Tables 2 and 3 together show the values of the samples of Sample Nos. 06, 22 and 23 of the first embodiment.

In the copper-based sintered alloy samples of Samples Nos. 06 to 31 of Table 2 and Table 3, the influence of the amount of the second hard phase can be investigated. In addition, by comparing copper-based sintered alloy samples of sample Nos. 28 and 32 to 38 of Tables 2 and 3, it is possible to investigate the influence of the kind of the second hard phase.

[Influence of the amount of the second hard phase]

With respect to the sample No. 06 which does not include the second hard phase, the samples of the samples Nos. 24 to 31 including the second hard phase have a reduced amount of wear, and as the amount of the second hard phase increases, And the like. On the other hand, in the samples Nos. 24 to 31 including the second hard phase, the thermal conductivity of the sample of the sample No. 06 which does not contain the second hard phase was lowered and the amount of the second hard phase was increased The thermal conductivity tends to decrease. For this reason, in the sample of the sample No. 31 in which the second hard phase amount is more than 5 mass%, the decrease of the thermal conductivity is remarkable, and the value is not satisfied twice the conventional iron-based sintered alloy sample of the sample No. 23.

As described above, it was confirmed that the abrasion resistance can be improved (the abrasion loss can be reduced) by dispersing the second hard phase, but the amount should be 5.0 mass% or less.

[Influence of kind of the second hard phase]

The samples of sample Nos. 28 and 32 to 38 differ in the type of the second hard phase. Here, the sample of the sample No. 28 is an example of the (G) ferromolybdenum hard phase, the sample of the sample No. 32 is an example of the (H) ferrochrome hard phase, and the sample of the sample No. 33 is the (I) ferro tungsten hard phase. The sample of the sample No. 34 is a hard phase sample in which the carbide particles of Cr are dispersed in the (A) iron-based alloy, the sample of the sample No. 35 is the sample of the carbide particles of Cr, Mo, V and / (C) is an example of a hard phase in which carbide grains of Mo, V, W and Cr and / or complex carbide grains of these elements are dispersed in an iron-based alloy (C). The sample of the sample No. 37 is an example of a hard phase in which molybdenum silicide particles are dispersed in the (E) iron-based alloy, and the sample of the sample No. 38 is an example of the hard phase in which the molybdenum silicide particles are dispersed in the (F) cobalt-based alloy.

It was confirmed that the samples of the sample Nos. 28 and 32 to 38 were less abrasive than the sample of the sample No. 06 which did not contain the second hard phase, contributing to the improvement of the abrasion resistance of the copper-based sintered alloy.

[Third Embodiment]

The copper powder, the nickel powder, the silicon powder and the graphite powder used in the first embodiment were prepared and added in the proportions shown in Table 4, and the mixed raw powder was molded and sintered under the same conditions as in Example 1 to obtain Sample No. 24 To 36 samples of copper-based sintered alloy were prepared. These samples were measured for thermal conductivity and abrasion resistance in the same manner as in the first example. The results are shown together in Table 4. In Table 4, the values of the samples of Sample Nos. 06, 22 and 23 of the first embodiment are also shown.

The influence of the amount of the graphite phase can be investigated in the samples of the copper-based sintered alloys of the sample Nos. 06 and 39 to 44 in Table 4. [

[Influence of amount of graphite phase]

The samples of Sample Nos. 39 to 43 containing C and containing graphite were found to have a C content, that is, a C content up to 3.0% by mass, in the samples of Sample No. 06 containing no C and containing no graphite The amount of abrasion tends to decrease with an increase in the amount of C, while the amount of abrasion tends to increase in the case of Sample No. 44 in which the amount of C exceeds 3.0 mass%. In addition, since the graphite powder inhibits the densification of the copper-based sintered alloy in sintering, the density of the sintered body tends to decrease as the amount of C, that is, the amount of graphite, increases. If the C content exceeds 3.0 mass%, the tendency that the amount of wear increases inversely is considered to be caused by the lowering of the density of the sintered body. In other words, since the decrease in density of the sintered body leads to the deterioration of the known strength, it is considered that the sample of Sample No. 44 in which the C content exceeds 3.0 mass% is increased in wear due to the influence of the deterioration of the known strength.

Further, the thermal conductivity tends to decrease with the increase of the amount of C due to the decrease of the density of the sintered body due to the increase of the amount of C, that is, the amount of the graphite, and in the sample of the sample No. 44 in which the amount of C exceeds 3.0 mass% And a value which is twice as large as that of the conventional iron-based sintered alloy sample of the sample No. 23 is obtained.

As described above, it was confirmed that the amount of C should be kept at 3.0% by mass or less although the abrasion resistance can be improved (abrasion loss can be reduced) by containing C and dispersing the black toner image.

The wear-resistant copper-based sintered alloy of the present invention combines heat conductivity and wear resistance, and knocking can be prevented even if the compression ratio of the engine is increased, thereby contributing to improvement in fuel economy of the engine. It is very suitable.

Claims (7)

Wherein a total composition is composed of a base composed of 2.0 to 16.0% of Ni, 0.2 to 4.0% of Si, and the balance of Cu and inevitable impurities and composed of pores and a copper or copper-nickel alloy in a mass ratio, And the nickel suicide has a size of 2 탆 or more. 2. A wear-resistant copper-based sintered alloy for a valve guide according to claim 1, wherein the nickel silicide is a nickel silicide. The method according to claim 1,
Wherein the nickel suicide having a size of 2 mu m or more is 2% or more in area ratio in the metal structure. The method according to claim 1 or 2,
Characterized in that the ratio of Ni to Si in the whole composition is from 0.05 to 0.35 of Si relative to Ni: 1. 2. A wear-resistant copper-based sintered alloy according to claim 1, The method according to claim 1 or 2,
Wherein the alloy composition further contains at least 3.0 mass% of at least one of Sn, P and Co in the total composition. Wherein a total composition is composed of a base composed of 2.0 to 16.0% of Ni, 0.2 to 4.0% of Si, and the balance of Cu and inevitable impurities and composed of pores and a copper or copper-nickel alloy in a mass ratio, And the nickel suicide has a size of 2 탆 or more,
Wherein at least one of (A) to (I) below is dispersed in a total amount of 5.0% by mass or less in the matrix, and further contains a selected component in the whole composition.
(A) a hard phase consisting of Cr: 4 to 25%, C: 0.25 to 2.4%, and the balance Fe and inevitable impurities, in which iron carbide particles are dispersed in the iron-
(B) at least one or more of Cr: 4 to 25%, C: 0.25 to 2.4%, Mo: 0.3 to 3.0% and V: 0.2 to 2.2%, and the balance of Fe and inevitable impurities , A hard phase in which carbide particles of Cr, Mo, V and / or complex carbide particles of these elements are dispersed in an iron-based alloy
(C), and the balance of Fe and inevitable impurities is composed of 4 to 8% of Mo, 0.5 to 3% of V, 4 to 8% of W, 2 to 6% of Cr, 0.6 to 1.2% A hard phase in which the carbide grains of Mo, V, W, Cr and / or complex carbide grains of these elements are dispersed in the iron-
(D) a hard phase in which molybdenum silicide particles are dispersed in an iron-based alloy, the balance being composed of Si: 0.5 to 10%, Mo: 10 to 50%, and the balance of Fe and inevitable impurities
At least one of 0.5 to 10% of Si, 10 to 50% of Mo, 0.5 to 10% of Cr, 0.5 to 10% of Ni, 0.5 to 5% of Mn, Fe and inevitable impurities, and the molybdenum silicide particles are dispersed in the iron-based alloy,
Wherein the molybdenum silicide particles are dispersed in the cobalt-based alloy, wherein the molar ratio of Si: 1.5 to 3.5%, Cr: 7 to 11%, Mo: 26 to 30% Prize
(G) mass ratio of ferromolybdenum hard phase consisting of 55 to 65% of Mo, 4% or less of C, 2% or less of Si and the balance of Fe and inevitable impurities
(H) a ferrochrome hard phase comprising 50 to 75% of Cr, 1% or less of C, 8% or less of Si, and the balance of Fe and inevitable impurities
(I) a ferro-tungsten hard phase consisting of 75 to 85% of W, 0.5% or less of C, 0.5% or less of Si, and the balance of Fe and inevitable impurities The method according to claim 1 or 2,
And further contains C: 3.0% by mass or less in the whole composition, and a graphite phase is dispersed in the pores. The method according to claim 1 or 2,
And a density of 7.5 kg / m < 3 > or more.

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