JPS6253580B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing sintered alloys, and is a novel sintered alloy that has excellent strength, toughness, and corrosion resistance, and has stable performance with little variation, as well as excellent properties in terms of coefficient of friction and other bearing functions. This is an attempt to obtain a method for producing gold. Various sintered alloys have been known for use as bearing materials and other materials, but they can be roughly divided into copper-based and iron-based.
Sn, Cu-Sn-C, Cu-Sn-Pb-C alloys, etc., and iron-based alloys such as Fe-C, Fe-Pb-C, Fe-
Various types of alloys such as Cu and Fe-Cu-C alloys have been proposed and put into practical use. However, in such conventional products, iron-based products have higher hardness than copper-based products, so they do not necessarily fit well with shaft materials, etc., and are inferior in corrosion resistance, etc., but the machine Copper-based materials have the advantage of having excellent physical properties, allowing for thin walls, and being relatively inexpensive. Copper-based materials have a symmetrical relationship with respect to these properties. As an intermediate between these, there is an iron-copper system in which only copper is added in the range of 5 to 30% to iron, but this type has a structure in which simple particles of iron and copper are exposed on the bearing surface. This has disadvantages such as copper particles adhering to the shaft surface and peeling off, increasing the coefficient of friction and generating heat, shortening the life of the bearing. As will be described later, when sintering a powder compact containing components such as zinc that vaporize and escape during sintering, the compacted body may be charged into carbon powder or placed in a metal case and covered with a lid. Reducing vaporization escape is disclosed in Japanese Patent Publication No. 27-2956 by the present applicant,
Published by Nikkan Kogyo Shimbun on July 25, 1962, edited by Powder Metallurgy Technology Association, “Powder Metallurgy Technology Course”, Volume 8, p. 135,
Published by Gijutsu Shoin on June 1, 1962, edited by Powder and Powder Metallurgy Association, “Design Handbook of Sintered Machinery Parts”, page 47, Showa
They are well-known as they are described in "Nonferrous Metal Materials", page 26, published by Corona Publishing on May 30, 1946. The present invention was devised after repeated studies in view of the above-mentioned circumstances. Mixed metal powder containing 3 to 20 parts by weight of bronze powder (if necessary, 6 parts by weight)
It is proposed to compact and sinter 1 part by weight of graphite powder or 0 to 3 parts of molybdenum or molybdenum disulfide (or a mixture of both). That is, to further explain the present invention, based on the technical concept as described above, the present inventor has developed an iron,
As a result of detailed studies on various sintered alloys using copper and zinc, we found that the behavior during sintering differs when copper and zinc are combined as single substances and when they are used as an alloy of brass. I discovered something different. The brass lid is generally made of brass.
Cu: 59 to 88%, containing one or more of Pb, Sn, Al, and Fe in a range of 1% or less each, with the remainder
It has a composition of Zn (Zn is generally 10 to 39%), and even within this range, different properties can be obtained by varying the percentage range of each component. However, the melting point of such brass is considerably lower than that of pure copper. However, when iron, copper, and zinc powders are mixed as described above, Zn has a relatively low melting point of about 420℃, whereas Cu has a relatively low melting point of about 420℃.
Their melting points are high at 1083℃ and Fe at 1539℃, respectively, and even if these three types of metal powder are simply mixed and molded and sintered, segregation of Zn will occur and the β phase with high Zn content will be formed. In addition, when Zn is added as a single substance and mixed, even if it is added as a solid brass, the Zn will be diffused, and it is necessary to bury it in charcoal powder or in an iron box to reduce this dispersion. Even if it is sintered by storage, this dispersion cannot be effectively prevented, and the preferable and stable characteristics described later due to the addition of brass cannot be obtained, and the product lacks compatibility with the preferred shaft material, etc. However, brass powder obtained by once alloying Cu and Zn is used as the main ingredient, and 3 to 20 parts by weight of bronze powder is added to 100 parts by weight of the mixture with this Fe powder. In the case of
1100℃, which is generally adopted for Fe-based sintered metals, even if Fe powder is mainly used.
The Zn contained in the brass during sintering is not only sintered at a considerably lower temperature than the before and after.
During sintering, part of the brass component becomes eutectic with iron to create a brass-iron alloy composition, and especially with such a brass-iron alloy composition. Zn has a tendency to coat the surface of iron particles, and exhibits corrosion resistance due to Zn. Even when a considerable amount of iron powder is mixed, the color and feel are similar to those of brass sintered alloys, and the composition is uniform, making it more durable than iron. - There is no unavoidable segregation in copper sintered products, and a stable sintered alloy with little variation in performance can be obtained. It is clear that a material that is uniform, has no segregation, prevents Zn from dispersing, and coats the surface of Fe particles with a brass-iron alloy to ensure corrosion protection by Zn exhibits sufficient corrosion resistance.
In addition, the material of the present invention, in which Fe particles exist in the core and is coated with a brassy alloy that suppresses the diffusion of Zn, has a mechanical strength equal to or greater than that of conventional iron-based sintered alloys. Furthermore, due to the brass and bronze coating layers, good conformability to the shaft material etc. can be obtained. The mixing ratio of the Fe powder and the brass powder can be changed as appropriate within the range of 30 to 70 parts by weight of the brass powder and 70 to 30 parts by weight of the Fe powder. In other words, if the brass powder is less than 30 parts by weight and the iron powder is more than 70 parts by weight, it will become similar to a mere iron-based sintered body and a sufficient alloy layer with brass will not be obtained. The characteristics of the invention cannot be effectively obtained. In addition, if the brass powder is 70 parts by weight or more and the iron powder is less than 30 parts by weight, the above-mentioned
The core effect of Fe particles cannot be obtained, and the mechanical strength etc. are inferior. In addition, to prevent the Zn from escaping when a mixture of iron powder and brass powder is compressed and sintered, it must be stored in an iron box.
Alternatively, it is necessary to add at least 3 parts by weight of bronze powder to 100 parts by weight of the mixed powder instead of just burying it in the carbon powder, thereby properly dispersing the Zn content during sintering. It can be prevented.
The upper limit of the bronze powder is 20 parts by weight; adding more than this limit is not economical and tends to increase the Cu content, resulting in a slight decrease in mechanical strength. The sintering temperature should be adjusted accordingly depending on the amount of brass powder mixed within the above range. For example, if the brass powder is 30 parts by weight and the iron powder is 70 parts by weight,
In the case of the present invention as described above, the temperature is around 900°C, and when the brass powder is 70 parts by weight and the iron powder is 30 parts by weight, the temperature is around 820°C. This is the reason why these characteristics can be effectively exhibited, and in the case of an intermediate composition relationship between them, the sintering temperature is adjusted according to the degree of the relationship. Furthermore, the performance can be further improved by adding graphite powder in an amount of 6 parts by weight or less and molybdenum or molybdenum disulfide powder in an amount of 3 parts by weight or less to 100 parts by weight of the above-mentioned main powder. be able to. A specific manufacturing example of the product according to the present invention will be described below. Production example 1 Cu: 60.5%, Zn: 38.5%, balance Pb, Sn,
60~ obtained by melting and spraying a brass casting consisting of 0.5% or less of Al and Fe and unavoidable impurities.
350 mesh brass powder (commercially available so-called 6,4 brass powder), 150 to 250 mesh reduced iron powder, and
Sprayed bronze powder (100 mesh or less) containing Sn: 10% was prepared, and these metal powders were mixed as shown in Table 1 below. That is, A-1 to A-6 are according to the present invention, A-1 to E-6 are comparative materials, and X is Fe90-Cu10.
The material and Y are Cu90-Sn10 material.

【table】

[Table] All of the above formulations have an outer diameter of 10
mm, inner diameter 4mm, height 8mm, porosity approximately 20%
It is formed into a bearing material of 30 due to temperature of 900℃
The bearing material obtained in this way was subjected to a sintering process for several minutes and then sized to produce a product.
The results are shown in Table 2 below, categorized by those with the same blending ratio of Fe and brass.

【table】

[Table] In other words, the comparative materials I-1, I-2, and I-3, which do not use bronze, lose their Zn content through sintering even when they are housed in an iron box and under conditions to prevent diffusion. In contrast, in the case of the present invention, even with just 3% bronze addition, this Zn loss is significantly reduced to at least one-third or less, and with 20% addition, Zn decreases by more than 2%. It can be reduced to about 1/7. In addition, if bronze is not used during sintering without being housed in an iron box or embedded in carbon powder, and bronze is not used,
The Zn% reached the 4-6% range, and the Zn% after sintering was 6-7% in group (a), 10-12% in group (b),
In group (c), it is about 17-19%. In addition, the average value and deviation value of the results of measuring the radial crushing strength of 30 pieces of each of these products are shown in Table 2. Not only does it show a considerably high value, but the deviation value is almost halved,
This clearly indicates that the volatilization of zinc during sintering was effectively prevented. Friction coefficient and temperature rise are the first factors regarding bearing performance.
As shown in Figure 3, the friction coefficient is particularly excellent in the high load and high PV value range, and the temperature rise is similar to that of conventional expensive copper-based sintered metal bodies (containing about 10% tin). It was confirmed that it was. Furthermore, the fluctuation state of the radial crushing strength with respect to the change in porosity is as shown in FIG. 4, and in any case, it was confirmed that the product was of excellent quality. Production Example 2 Comparative Example Ro-1 was prepared using the same brass powder and iron powder as in Production Example 1, and was mixed in a ratio of 50 parts of brass powder, 48 parts of iron powder, and 2 parts of graphite powder, and this was mixed with 20 parts of bronze powder.
Example B-1 of the present invention was prepared by further blending the following parts. Apart from this, using the same brass powder and iron powder,
Comparative Example Ro-2 was prepared by mixing 50 parts of brass powder, 50 parts of iron powder, and 2 parts of graphite powder, and Invention Example B-2 was prepared by further adding 3 parts of bronze powder. However, these inventive examples and comparative examples were molded in the same manner as in Production Example 1 described above,
Sintered. Furthermore, in addition to these examples of the present invention and comparative examples, there is a conventional example Conventional Example Y was prepared by mixing 90 parts of tin powder with 10 parts of tin powder, molding it, and sintering it at 800°C. Furthermore, regarding the sintered alloys of Examples B-1 and B-2 of the present invention, Comparative Examples Ro-1 and Ro-2, and Conventional Examples X and Y, each impregnated with the same turbine oil-based lubricating oil, The results of testing and measuring the bearing performance are as shown in Figure 5.
It was confirmed that bearing performance was improved over conventional copper-based bearings at 15 kg/mm ² or more (PV value of 1000 or more), and of course it had more favorable characteristics over the entire range than iron-based bearings. I found that it was even more preferable than the comparative example. In addition, the mechanical strength of the production examples of the present invention, comparative examples, and conventional examples as described above was examined, that is, the results of measuring the radial crushing strength of the products with various porosity adjustments after compression molding and sintering. As shown in FIG. 6, it was confirmed that the material according to the present invention exhibited superior mechanical strength than the conventional example regardless of the porosity, and was even better than the comparative example. The inventors of the present invention also studied other brass powders having the following component compositions as described above, and were able to obtain similar results with all of them. Cu with low Zn content within the range of the present invention: 83 to 88
%, Zn: 22-27%, Pb: 0.5% or less, Sn, Al,
The total value of Fe is 1.0% or less. Cu with intermediate Zn content within the range of the present invention: 65 to 70
%, Zn: 30-35%, Pb: 0.5-3%, Sn: 1%
Below, Al: 0.5% or less, Fe: 0.8% or less. Moreover, various mechanical parts such as gears, electric motor parts, valve materials, etc. can be manufactured by appropriately changing the compounding ratio, molding density, and sintering temperature within the above-mentioned ranges. According to the present invention as explained above, brass is used, and by using an appropriate amount of bronze powder, the dispersion of Zn in the brass is appropriately prevented, and in terms of conformability to shaft materials and corrosion resistance, compared to conventional copper-based It is equivalent to or better than sintered alloys, and its mechanical strength is comparable to that of conventional iron-based sintered alloys.In addition, it has stable characteristics with little variation in quality. It is possible to accurately provide a new sintered alloy, and it has characteristics such as less mold wear during compression molding than conventional iron-based sintered alloys, making it suitable for industrial use. This is a highly effective invention.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and FIGS. 1 to 3 are charts showing the results of measuring the bearing performance of the sintered alloy according to Production Example 1 of the present invention together with the conventional example, and FIG. Figure 5 is a diagram showing the results of measuring the mechanical performance of a representative example together with conventional examples and comparative examples. FIG. 6 is a chart showing the same relationship as FIG. 4 regarding the mechanical performance.

Claims (1)

[Claims] 1 Cu: 59-88% and any one of Pb, Sn, Al, Fe
Containing one species or two or more species in a range of 1% or less each,
30 to 70 parts by weight of brass powder, the balance of which is Zn, and iron powder
Mainly containing 70 to 30 parts by weight, 3 to 20 parts by weight of bronze powder is blended to 100 parts by weight of these powders, and the blended metal powder is compacted and then sintered. Manufacturing method of sintered alloy.