JPH0346536B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a sintered alloy for Al-Pb bearings. Recently, Al-Pb alloys have attracted attention as bearing materials or superconducting materials, and various studies have been conducted on them. However, Al-Pb alloy is extremely difficult to manufacture for the following reasons. In other words, in Figure 1
As shown in the Al-Pb phase diagram, the maximum solubility of Pb in Al is 0.02% by weight (1.5 atomic%) at a monolithic temperature of 658.5°C, and the solubility of Al in Pb is 0.9% by weight (0.12 atomic%). is also extremely small. Furthermore, the specific gravity of Al is 2.70, while that of Pb is 11.36, and the specific gravity of Pb is 4.2 times that of Al. Therefore, when producing an Al-Pb alloy by casting, for example, in normal melting, Al and Pb separate into upper and lower phases due to the difference in specific gravity, and when cooled, the Al phase melts at 658.5°C and the Al phase melts at 326.8°C. The Pb phase solidifies separately. This indicates that the temperature is higher than the temperature of the melt solubility curve (for example, 1080℃ or higher for 20% Pb),
For 40% Pb, there is a method of rapid cooling from a high temperature (1300℃ or higher). However, this method
Because Pb is melted at high temperatures, it oxidizes violently in the atmosphere and must be manufactured in an inert atmosphere.
Difficult to manufacture. In addition, when manufacturing by powder metallurgy, since the difference in specific gravity between Al powder and Pb powder is large, the two powders tend to separate into two phases during the mixing process, making it difficult to mix them uniformly. Moreover, since the solubility of both powders is extremely low, sintering is also difficult. On the other hand, a mechanical alloying method was developed in 1973 that made it possible to produce an alloy system in which multiple constituent elements were uniformly dispersed using the conventional method, using a ball mill. It is disclosed in Publication No. 37631. However, the above publication does not specifically disclose an Al-Pb sintered alloy that is a combination of Al powder and Pb powder, and the Al-Pb sintered alloy is still useful.
No sintered alloy was obtained. In addition, the inventors described in the above publication, J.S., JSBenjamin, etc.,
Furthermore, two types of metal powder were mixed using a ball mill.
Although it has been reported that two types of metals have a layered distribution structure or a random homogeneous distribution structure, there has been no specific report regarding Al-Pb sintered alloys. Therefore, we have traditionally developed useful materials with excellent mechanical performance.
It was hoped that an Al-Pb sintered alloy would emerge. The present invention was made in view of these points, and has a distribution structure in which Pb is uniformly dispersed in layers or particles in Al, and has excellent mechanical performance such as damping ability characteristics, friction characteristics, and heat generation characteristics. The purpose of the present invention is to provide a sintered alloy for Al-Pb bearings that can be used as a high-quality bearing material. That is, the Al-Pb sintered alloy for bearings of the first aspect of the present invention is a sintered alloy for Al-Pb bearings consisting of 5 to 40% by weight of Pb and the balance Al, wherein the balance is Al.
Al and Pb are characterized by having a distribution structure in which Pb is distributed in layers in the remaining Al. Further, the Al-Pb bearing sintered alloy of the second invention of the present invention is an Al-Pb bearing sintered alloy comprising 5 to 40% by weight of Pb and the balance Al.
And Pb is characterized by having a distribution structure in which Pb is distributed in granular form in the remaining Al. Next, the sintered alloy for Al-Pb bearings of the present invention and its manufacturing method will be explained with reference to the drawings. First, Al powder and Pb powder, which are components of the sintered alloy for Al-Pb bearings of the present invention, are mixed so that the Pb powder content is 5 to 40% by weight. As Al powder, 20
A spray powder of about 500 mesh, particularly preferably 80 to 325 mesh, is used. As the Pb powder, fine powder of 20 mesh or less, particularly preferably 200 mesh
~350 mesh of spray powder is used. Al powder and Pb
The use of such a fine powder for Al
This is to disperse the Pb powder as uniformly as possible in the powder. In addition, the reason why Pb contained in Al was limited to 5 to 40% by weight was to consider the damping ability (vibration absorption) characteristics and strength of the resulting Al-Pb bearing alloy.
If it is less than 40% by weight, the damping capacity characteristics are small and it is not suitable for a bearing, and if it exceeds 40% by weight, the strength is insufficient for a bearing. Next, the mixed powder of Pb powder and Al powder is mixed into a second powder.
Using a ball mill as shown in the figure, a composite is produced by mechanically forming a Pb phase around an Al phase. Ball mill has rotating shaft 1
A stand 2 is attached to the top, a storage container 3 is placed on one side, and cemented carbide balls 4 of various sizes, for example, diameters of 12 mm, 15 mm, 20 mm, and 30 mm, are placed in the storage container 3. . To explain further, the storage container 3 has a cylindrical shape, and the dimensions of the internal storage space are 70 mm in inner diameter and 80 mm in height, and the central axis of the cylinder is offset by about 50 mm with respect to the rotation axis 1. It is attached to the stand 2 in this manner, and only one ball 4 made of cemented carbide is inserted therein. When the mixture of Al powder and Pb powder is put into the storage container 3 of this ball mill and the storage container 3 is rotated at a predetermined speed, due to the action of the balls 4 which have obtained centrifugal force,
Pb powder is uniformly dispersed in Al powder and mechanically composited. When manufacturing the Al-Pb sintered alloy for bearings of the present invention, it is necessary not only to uniformly disperse Pb in Al, but also to reduce the total amount of work applied to the composite when producing the composite using a ball mill. By variable adjustment, the final product Al of the present invention
-The distribution structure of Pb in the sintered alloy for Pb bearings is variably adjusted. This variable adjustment of the total amount of work by the ball mill can be done by adjusting the processing time to be longer or shorter when the same ball mill is rotated at a constant speed, or by varying the rotation speed of the same ball mill. Alternatively, a plurality of ball mills with different performances may be prepared, and each ball mill may be used depending on the purpose. The degree of variation in the distribution structure of Pb in Al based on the variable adjustment of the total work by this ball mill is as follows:
Depending on the change in total work, the final product Al
- How the hardness and Pb distribution structure of the Pb sintered alloy change is determined in advance, for example, as shown in Figures 3 and 4, and then the produced Al-Pb sintered alloy is examined. The determination can be made by measuring the change tendency of the total work and hardness and comparing the change tendency with the data shown in FIG. The specific contents will be explained based on FIGS. 3 and 4. Figure 3 shows the processing time and micro milling at a measured load of 25 g when one cemented carbide ball 4 with a diameter of 12 mm is placed in the ball mill shown in Figure 2 and rotated at approximately 400 rpm to perform compounding. This shows the relationship with Vickers hardness. Black circle (●) in the diagram
The sample is a mixture of -80/+150 mesh Al powder and -200 mesh Pb powder to give Al-20 weight% Pb.The white circle (○) is a -150/+325 mesh Al powder, −200 mesh of Pb powder and Al
- This is a sample mixed so that the Pb content is 20% by weight.
In addition, (x) indicates a comparison sample using only Al powder of -150/+325 mesh. As is clear from this figure 3, the processing time is 1000
Up to 1,000 minutes, the hardness fluctuates high and low, but macroscopically it shows an increasing trend where the hardness gradually increases.When the processing time exceeds 1000 minutes, the hardness shows a decreasing trend where it gradually decreases, and then becomes a constant value. It changes like this. In addition, when this treatment time is less than 1000 minutes, Pb is distributed in a layered manner as shown in the micrograph in FIG. 4A. On the other hand, anything over 1000 minutes,
As shown in the figure (b), the Pb phase is distributed in a granular manner. Furthermore, the generation process of the Pb phase distribution structure will be explained based on FIG. When the compounding process of AI powder and Pb powder using a ball mill starts, the Pb powder is mechanically and forcibly pressed onto the outer periphery of the Al powder, and the Pb powder is forced onto the grain boundaries of the Al powder.
It exhibits a distribution in which Pb is included. After that, as the total amount of work by the ball mill increased, one
Further around the Pb which is crimped around the Al particles
Pb is compressed and the unit particles become coarser.
When this coarsening progresses to a certain extent, Pb causes slippage due to its small shear stress, causing the coarsened unit particles to bend and become finer. Then, as the total work of the ball mill increases, the particles become coarser and finer, and the Pb phase is distributed in layers. In Figure 3, the processing time is
Macroscopically, the hardness of Al-Pb sintered alloy for bearings tends to increase within 1000 minutes.
This is because the crimped particles between Pb and Pb gradually become finer, and when viewed microscopically, the hardness rises and falls because the hardness increases when the crimped particles become coarser and decreases when they become finer. be. The refinement of each particle in the layered distribution structure of Pb progresses as the total work of the ball mill increases, and the total work of the ball mill increases even further than when the hardness of the sintered alloy for Al-Pb bearings reaches its maximum value. As Pb increases, each particle becomes finer and Pb becomes granular and distributed. In the embodiment of FIG. 3, the bifurcation point between layered and granular depends on whether the processing time is less than or more than about 1000 minutes. In this way, when the hardness tends to increase in response to an increase in the total amount of work, the Pb distribution structure is layered, and when the hardness tends to decrease, the Pb distribution structure is granular. Therefore, for the Al-Pb bearing sintered alloy with any Pb component ratio to be manufactured, the relationship between the total work and hardness is determined, and from the change tendency of the hardness, the Pb The distribution structure of can be appropriately determined. For example, in the example shown in Figure 3, in order to obtain a sintered alloy for Al-Pb bearings having a distribution structure in which Pb is dispersed in layers, a treatment time of 300 to 600 minutes is appropriate; The hardness of sintered alloy for bearings is 40
~60Kg/ ^mm2 . In addition, in order to obtain a sintered alloy for Al-Pb bearings in which Pb is dispersed in granular form, the processing time is preferably about 2000 minutes, and the hardness at this time is 50
It is around Kg/ ^mm2 . Next, in this example, the composite is compression molded and then sintered to produce a sintered alloy for an Al--Pb bearing. Compression molding and sintering here are performed according to conventional methods, for example, compression molding is performed at a pressure of 3 tons/cm ² or less, and sintering is performed at a temperature of 500 to 900°C and a degree of vacuum of approximately 10 ^-2 mmHg. Do this for 0.5-1.5 hours. Through this sintering, the Al powders are sintered together, and Pb is sintered while maintaining its dispersed state in the green compact, that is, the layered distribution structure or the granular distribution structure. Note that after mechanically compounding the mixture of Al powder and Pb powder, it may be formed into a predetermined shape without compression molding, and then sintered. The thus obtained sintered alloy for Al--Pb bearings of the present invention has good damping performance characteristics and excellent friction characteristics. Also, since it is a sintered material, it can be impregnated with oil. Therefore, it is extremely effective as a bearing material. A sintered alloy for Al-Pb bearings in which the Pb phase is distributed in a granular manner has better damping performance characteristics than one in which the Pb phase is distributed in a layered manner. This is because Pb, which has a smaller shear stress, is more finely and uniformly distributed in the granular distribution structure. Next, specific examples of the present invention will be described. In the following examples, a spray powder that passes through 80 meshes was used as the Al powder, and a spray powder that passes through 100 meshes was used as the Pb powder. Example 1 () 95-60% by weight of Al powder, 5-40% of Pb powder,
Using the ultra-hard high-speed centrifugal ball mill, dry mix for 400 minutes under the same operating conditions as above to create a mechanically composite Al-Pb composite powder,
Then put it into a mold and apply a molding pressure of 2 tons/cm ²
The ^Al-
Sintered alloys for Pb bearings (No. 1 to No. 5) were obtained. Each of the sintered alloys for Al-Pb bearings obtained in this way
The dispersion state of Pb was observed and the bending strength was measured.
The results are shown in Table 1 along with the manufacturing conditions. Furthermore, as a representative of samples No. 1 to No. 5, a microscopic photograph of the surface of the sintered alloy No. 5 is shown in FIG. 6A. () Dry mixing 95-60% by weight of Al powder and 5-40% by weight of Pb powder in a carbide high-speed centrifugal ball mill for 2000 minutes to create a mechanically composite Al-Pb composite powder and mix it. This was formed at 2 tons/cm ² and then fired in a vacuum (~10 ^-2 mmHg) at a firing temperature of 650°C for 30 minutes to produce Al-Pb bearing sintered alloys (No. 6 to No. 10). I got it. Table 1 shows the measured values of the Pb dispersion state and bending strength of each of the Al--Pb bearing sintered alloys obtained in this way. Furthermore, as a representative of samples No. 6 to No. 10, a microscopic photograph of the surface of the sintered alloy No. 10 is shown in FIG. 6B. Example 2 Specific wear amounts were measured for samples Nos. 1 to 5 in an oil-free state, and samples Nos. 6 to 10 in an oil-free state and an oil-containing state, and their friction resistance was investigated. The results are shown in Table 2. For comparison, lead bronze type 4 (No. 11), which is said to have the best wear resistance among conventional bearing materials, and Al-4.4 wt% Cu-0.8 wt% Si- The specific wear amount was measured for 0.4% by weight Mg (No. 12), and the results are also listed in Table 2. In this case, the test machine used was an Okoshi type rapid wear test machine, with a friction speed of 3.62 m/sec and a final load of
It was set at 2.1Kg/ ^mm2 . From Table 2, the sintered alloy for Al-Pb bearings of the present invention is:
Although there are variations in numerical data in the case of oil-free bearing materials, it has wear resistance that is almost equal to or higher than that of conventional bearing materials with the highest wear resistance, and has better friction characteristics than conventional bearing materials. It turns out that it is excellent. In particular, samples Nos. 5, 8, 9, and 10 each have superior specific wear values by an order of magnitude. Example 3 Samples No. 3 and 8 according to the present invention and comparative sample No. 11 were tested for heat generation characteristics due to friction in an oil-containing state using an Okoshi type rapid wear tester, with friction characteristics of 3.62 m/sec,
The final load was measured under the condition of 5 kg, and the result was
As shown in the figure. In the figure, A ₃ is the sample No. 3, and A ₈ is the sample No. 3.
Sample No. 8 and A ₁₁ indicate sample No. 11, respectively. Figure 5 shows that the heat generation properties of the Al-Pb sintered alloy for bearings of the present invention are different from that of the lead bronze based bearing material, which is considered to be the conventional bearing material with the best heat generation properties. It can be seen that the heat generating properties are almost the same as those of the conventional example, and those having a granular distribution structure have even better heat generating properties, which are extremely excellent. Example 4 The attenuation capacity of samples Nos. 1 to 10 was measured, and the results are shown in Table 3. For comparison, pure aluminum sintered material (No. 13), pure aluminum cast material (No. 14) and Al-4.4 wt% Cu-0.8 wt% Si-0.4 wt% Mg
The damping capacity of the sintered material (No. 15) was measured and is also listed in Table 3. Here, the damping ability is a value measured at a strain amplitude of 5×10 ⁻⁴ and a vibration frequency of 300 to 600 C/S by the both-end free transverse vibration method. From Table 3, it can be seen that the sintered alloy for Al--Pb bearings of the present invention has far better damping performance characteristics than conventional ones, and can reduce vibrations that are a source of noise in bearings. In addition, Al-
It can be seen that the sintered alloys for Pb bearings (Nos. 6 to 10) have better damping ability than those distributed in layers (Nos. 1 to 5) with the same composition. As described above, the Al-Pb bearing sintered alloy of the present invention is
Because it has a distribution structure in which Pb is dispersed in layers or particles in Al, it has excellent mechanical properties such as friction characteristics, damping ability characteristics, and heat generation characteristics, making it extremely effective as a bearing material. play.

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[Table] By the way, the sintered alloy for Al-Pb bearings of the present invention having the above structure is composed of two elements, Al and Pb. A sintered alloy for bearings (hereinafter referred to as 3
The sintered alloy for bearings will be explained below. This ternary sintered alloy for bearings includes Al and Pb, which have the same components as those of the present invention, and further contains a small amount of other active elements, such as Mg, which is an element that activates sintering of Al powder together. It is added in an amount of 2% by weight based on the entire alloy. This Mg forms Al ₃ Mg ₂ with Al on the other hand,
It becomes an alloy of Al ₃₀ Mg ₂₃ and Al ₁₂ Mg ₁₇ , and the other
It becomes an alloy of Mg ₂ Pb with Pb, and active sintering occurs between Al powders and Pb powders, and the Mg of both alloys
The parts are strongly connected to each other, and Mg is connected to Al and
It is thought that the strength of the produced ternary sintered alloy for bearings is greatly increased by solid solution in Pb. Next, a specific example will be explained. In the following examples, the Al powder used was a sprayed powder that passed through 80 meshes, the lead powder used as a sprayed powder that passed through 100 meshes, and the Mg powder used as a sprayed powder that passed through 200 meshes. Example 1 () 95-60% by weight of Al powder, 5-40% of lead powder,
Using the ultra-hard high-speed centrifugal ball mill, dry mix for 400 minutes under the same operating conditions as above to create a mechanically composite Al-Pb composite powder,
2% by weight of Mg powder is added to the total weight of this, further mixed, then put into a mold, formed at a molding pressure of 2 tons/cm ² , and then fired at a temperature of
Sintering was performed at 650° C. in vacuum (~10 ^-2 mmHg) for 30 minutes to obtain ternary bearing sintered alloys (No. a to No. e). The dispersion state of Pb in each of the ternary sintered alloys for bearings thus obtained was observed, and the bending strength was measured. The results are shown in Table 4 along with the manufacturing conditions. () Dry mixing 95-60% by weight of Al powder and 5-40% by weight of Pb powder in a carbide high-speed centrifugal ball mill for 2000 minutes to create a mechanically composite Al-Pb composite powder, and further Magnesium was added in an amount of 2% by weight based on the total weight, further mixed, and formed at 2 tons/cm ² , followed by firing at a temperature of 650°C.
Bake in vacuum (~10 ^-2 mmHg) for 30 minutes at
Sintered alloys (No.f to No.j) for base bearings were obtained. The measured values of the Pb dispersion state and bending strength of each ternary bearing sintered alloy obtained in this way were measured in the fourth test.
Shown in the table. () 80% by weight of Al powder and 20% by weight of Pb powder were dry mixed for 2000 minutes in a carbide high-speed centrifugal ball mill.
Create mechanically composite Al-Pb alloy powder,
Magnesium is 2% by weight based on the total weight of this
Add and mix further, then bake at a temperature of 600 to 900.
Bake for 30 minutes in vacuum (~10 ^-2 mmHg) at ℃3.
Sintered alloys (No. k1 to No. o) for base bearings were obtained. Table 4 shows the measured values of the Pb dispersion state and bending strength of each of these ternary bearing sintered alloys. Example 2 Specific wear amounts were measured for samples No. a to e, h, and j in oil-free and oil-containing states, and their friction resistance was investigated. The results are shown in Table 5. For comparison, lead bronze type 4 (No. 11) and Al-4.4 wt%Cu
The specific wear amount was measured for -0.8 wt% Si-0.4 wt% Mg (No. 12), and the results are also listed in Table 5. In this case, the test machine used was an Okoshi type rapid wear test machine, with a friction speed of 3.62 m/sec and a final load of
It was set at 2.1Kg/ ^mm2 . From Table 5, it can be seen that the ternary sintered alloys for bearings of each of the examples described above have superior frictional characteristics compared to the conventional ones, similar to each of the examples of the present invention. Example 3 The heat generation characteristics due to friction in the oil-containing state of Sample Nos. c and h according to this example and Comparative Sample No. 11 were measured using an Okoshi type rapid abrasion tester at a friction property of 3.62 m/sec and a final load of 5 kg. Measurements were made under these conditions, and the results are shown in FIG. In addition, in the figure, A _c is No.c sample A _h is No.h
A 11 indicates sample No. 11, and A ₁₁ indicates sample No. 11, respectively. From FIG. 5, it can be seen that the heat generation characteristics of the ternary bearing sintered alloy of the above example are extremely excellent, as in each of the above embodiments of the present invention. Example 4 The attenuation capacities of samples No. a to j were measured and are shown in Table 6. For comparison, pure aluminum sintered material (No. 13) and pure aluminum cast material (No. 13) were used.
14) and Al-4.4 wt.% Cu-0.8 wt.% Si-0.4 wt.% Mg sintered material (No. 15) were measured for damping capacity, and the results are also listed in Table 6. Here, the damping ability is a value measured at a strain amplitude of 5×10 ⁻⁴ and a vibration frequency of 300 to 600 C/S by the both-end free transverse vibration method. From Table 6, it can be seen that the ternary sintered alloys for bearings of each of the present examples have damping capacity characteristics far superior to those of the conventional ones, as in each of the examples of the present invention.

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【table】 [Brief explanation of drawings]

Fig. 1 is a state diagram of the Al-Pb alloy, Fig. 2 is a sectional view of a ball mill used to manufacture the sintered alloy for Al-Pb bearings of the present invention, and Fig. 3 is a diagram showing the processing time and Al-Pb alloy. A diagram showing the relationship between the micro-Vickers hardness of the sintered alloy for Pb bearings. Figure 4A is a micrograph of the sintered alloy for Al-Pb bearings of the present invention in which Pb is distributed in layers, and Figure 4B is the micrograph of the sintered alloy for Al-Pb bearings of the present invention in which Pb is Micrographs of the sintered alloy for Al-Pb bearings of the present invention distributed in granular form, Figure 5 is a diagram showing heat generation characteristics due to friction, Figure 6 is a diagram showing heat generation characteristics due to friction.
Figure A is a micrograph of the Al-Pb sintered alloy for bearings of the present invention according to sample No. 5 in which Pb is distributed in a layered manner. - This is a microscopic photograph of a sintered alloy for Pb bearings.

Claims (1)

[Claims] 1. Al- consisting of 5 to 40% by weight of Pb and the balance Al.
A sintered alloy for Pb bearings, wherein the remaining Al and
The Al-Pb sintered alloy for bearings is characterized in that Pb has a distribution structure in which Pb is distributed in layers in the remaining Al. 2 Al− consisting of 5 to 40% by weight of Pb and the balance Al
A sintered alloy for Pb bearings, wherein the remaining Al and
A sintered alloy for an Al-Pb bearing, characterized in that Pb has a distribution structure in which Pb is distributed in granular form in the remaining Al.