A copper-tin alloy powder and a method for producing the same

Abstract

The application discloses a copper-tin alloy powder and a preparation method thereof. The copper-tin alloy powder is spherical and has 3-level pores, and the loose bulk density is 1.8-2.9 g / cm 3 The 3-level pores are as follows: the first-level pore size is 20-200 µm; the second-level pore size is 5-30 µm; and the third-level pore size is 0.5-10 µm. The strength of the powder compact prepared by the method is high. During the pressing process, the metal powder is deformed, and the powder is attached together. The lower the loose bulk density of the powder is, the larger the attached area is, and the better the strength of the green compact is. The strength of the bronze green compact prepared by the method is very high, and the strength of the green compact is 6-12 MPa.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper-tin alloy powder processing, and particularly relates to a copper-tin alloy powder and a preparation method thereof. BACKGROUND

[0002] The copper-tin 10 oil-containing bearing is a kind of porous material, which has a porous structure, is soaked in oil, and makes the micropores full of lubricating oil to become an oil-containing bearing. When the bearing works and rotates, the lubricating oil flows from the pores to the contact surface to generate oil film lubrication, and when the work is stopped, the lubricating oil returns from the contact surface to the pores of the bearing. The bearing is pressed and sintered from copper-tin 10 powder, and in the production process, the bearing blank is prone to be knocked during rotation. If the strength of the bearing blank is not good, the powder is prone to fall off, the corner is knocked off, and other defects are caused. In addition, the pore structure in the bearing also affects the overflow and backflow of the lubricating oil during the bearing operation. If large pores appear, the oil is easy to be thrown out and lost during high-speed rotation of the bearing. The pore structure with interconnected and small pores has better effect. SUMMARY

[0003] In order to overcome the deficiencies in the prior art, a copper-tin alloy powder with moderate and interconnected pores, which can be better applied to the manufacture of oil-containing bearings, is provided, and the technical scheme of the application is as follows:

[0004] A preparation method of a copper-tin alloy powder, comprising the following steps:

[0005] Step 1: mixing copper powder and copper-tin alloy powder to obtain a mixed powder with a tin content of 10wt%;

[0006] Step 2: preparing glue, dissolving a high molecular binder in water to obtain glue with a high molecular binder mass fraction of 1-10%, and the high molecular binder is polyvinyl alcohol, cellulose, or xanthan gum, etc.

[0007] Step 3: granulating the mixed powder with the glue prepared in step 2 to obtain a granulated powder with a particle size of less than 250µm;

[0008] Step 4: performing high-temperature oxidation treatment on the granulated powder prepared in step 3, the oxidation temperature is 300-600℃, the oxidation atmosphere is air, and the oxidation time is 20-120min;

[0009] Step 5: performing high-temperature reduction treatment on the oxidized powder prepared in step 4, the reduction temperature is 400-800℃, and the reduction is performed under a reduction atmosphere for 30-120min;

[0010] Step 6: performing crushing and screening treatment on the reduced powder prepared in step 5 to obtain the final target product.

[0011] Preferably, the particle size of the mixed powder in step 1 is 10-60µm.

[0012] The particle size of the granulated powder in step 3 is 10-250µm.

[0013] The oxidation temperature in step 4 is 400-550℃.

[0014] The reduction temperature in step 5 is 500-700℃; the reduction atmosphere is hydrogen, ammonia decomposition gas or carbon monoxide.

[0015] A copper-tin alloy powder, spherical, with three levels of holes.

[0016] Further, the three levels of holes include first level holes between granulated particles, with a hole size of 20-200µm, second level holes inside the granulated powder, between original powder particles, with a hole size of 5-30µm, and third level holes left over after oxidation and reduction of the copper or copper alloy powder, with a hole size of 0.5-10µm.

[0017] The present application first bonds the powder together with high molecular glue, the alloy powder has good sphericity, after granulation, although it is spherical, it is bonded by small particle powders, the bulk density of the granulated powder is not high, on the contrary, it is reduced, the bulk density is 1.8-2.9g / cm 3 , the flowability of the powder after granulation is very good; secondly, during oxidation of the granulated powder, the copper expands, many holes are formed inside the copper particles, during reduction, the holes shrink, but are still preserved, the bulk density of the granulated powder is further reduced after reduction. The alloy powder with small hole particle size prepared by the present application is used to make bearings, the small holes can store oil, the smaller the hole, the greater the capillary force, the oil will not be thrown out during high speed operation of the bearing. The holes in the bearing are distributed in three levels, between granulated particles, inside the granulated particles, and oxidation holes of the small particles. Furthermore, the strength of the green compact prepared by the method of the present application is high, during pressing of the metal powder, deformation occurs, the powder is bonded together, the lower the bulk density of the powder, the greater the bonding area, and the better the strength of the green compact, the green bronze compact prepared by the present application has very high strength, the green compact strength is 6-12MPa. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Metallographic phase diagram of the granulated powder prepared in step 3 of Example 1;

[0019] Figure 2 Metallographic phase diagram of the powder after oxidation in step 4 of Example 1;

[0020] Figure 3 Metallographic phase diagram of the powder after reduction in step 5 of Example 1;

[0021] Figure 4 Metallographic phase diagram of the fracture of the sintered block after sintering of the powder prepared in Example 1. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0023] Embodiment 1

[0024] The copper-tin alloy powder was prepared according to the following steps:

[0025] Step 1: The copper powder was mixed with the copper-tin alloy powder to obtain a mixed powder with a tin content of 10wt%, and the particle size of the mixed powder was 20µm;

[0026] Step 2: Glue preparation, polyvinyl alcohol was dissolved in water, and the mass ratio of polyvinyl alcohol was 5%;

[0027] Step 3: The mixed powder was granulated with the glue prepared in step 2 to obtain a granulated powder with a particle size of less than 250µm, and the particle size of the granulated powder was 150µm. The prepared granulated powder is shown in Figure 1 .

[0028] Step 4: The granulated powder prepared in step 3 was subjected to high-temperature oxidation treatment, the oxidation temperature was 400℃, the oxidation atmosphere was air, and the oxidation time was 60min. The powder after oxidation is shown in Figure 2 .

[0029] Step 5: The powder after oxidation prepared in step 4 was subjected to high-temperature reduction treatment, the reduction temperature was 600℃, and the reduction time was 60min under the reduction atmosphere. The powder after reduction is shown in Figure 3 .

[0030] Step 6: The powder after reduction prepared in step 5 was subjected to crushing and screening treatment to obtain the final target product.

[0031] The above powder was sintered, and the pore structure in the original particles was still maintained after sintering. The green strength was 8 MPa, the powder flowability was 34s / 50g, and the powder bulk density was 2.3g / cm 3 .

[0032] Embodiment 2

[0033] The copper-tin alloy powder was prepared according to the following steps:

[0034] Step 1: The copper powder was mixed with the copper-tin alloy powder to obtain a mixed powder with a tin content of 10wt%, and the particle size of the mixed powder was 20µm;

[0035] Step 2: glue preparation, the mass ratio of polyvinyl alcohol is 10%;

[0036] Step 3: the mixed powder is granulated with the glue prepared in step 2, and a granulated powder with a particle size of 250µm is obtained;

[0037] Step 4: the granulated powder prepared in step 3 is subjected to high-temperature oxidation treatment, the oxidation temperature is 400℃, the oxidation atmosphere is air, and the oxidation time is 60min;

[0038] Step 5: the oxidized powder prepared in step 4 is subjected to high-temperature reduction treatment, the reduction temperature is 600℃, and the reduction time is 60min under the reduction atmosphere;

[0039] Step 6: the reduced powder prepared in step 5 is subjected to crushing and screening treatment to obtain the final target product.

[0040] The above powder is sintered, and the pore structure in the original particles is still maintained after sintering. Test results show that the green strength is 7.5 MPa, the powder flowability is 32s / 50g, and the powder bulk density is 2.5g / cm 3 .

[0041] Example 3

[0042] The copper-tin alloy powder is prepared according to the following steps:

[0043] Step 1: copper powder and copper-tin alloy powder are mixed to obtain a mixed powder with a tin content of 10wt%, and the particle size of the mixed powder is 10µm;

[0044] Step 2: glue preparation, the mass ratio of cellulose in water is 2%;

[0045] Step 3: the mixed powder is granulated with the glue prepared in step 2, and a granulated powder with a particle size of 100µm is obtained;

[0046] Step 4: the granulated powder prepared in step 3 is subjected to high-temperature oxidation treatment, the oxidation temperature is 400℃, the oxidation atmosphere is air, and the oxidation time is 60min;

[0047] Step 5: the oxidized powder prepared in step 4 is subjected to high-temperature reduction treatment, the reduction temperature is 600℃, and the reduction time is 60min under the reduction atmosphere;

[0048] Step 6: the reduced powder prepared in step 5 is subjected to crushing and screening treatment to obtain the final target product.

[0049] The above powder is sintered, and the pore structure in the original particles is still maintained after sintering. Test results show that the green strength is 9 MPa, the powder flowability is 30s / 50g, and the powder bulk density is 2.1g / cm 3 .

[0050] Example 4

[0051] The copper-tin alloy powder is prepared according to the following steps:

[0052] Step 1: Mix the copper powder with the copper-tin alloy powder to obtain a mixed powder with a tin content of 10wt%, and the particle size of the mixed powder is 20µm;

[0053] Step 2: Prepare the glue by dissolving xanthan gum in water, and the mass ratio of xanthan gum is 2%;

[0054] Step 3: Granulate the mixed powder with the glue prepared in Step 2 to obtain a granulated powder with a particle size of 100µm;

[0055] Step 4: Perform high-temperature oxidation treatment on the granulated powder prepared in Step 3, the oxidation temperature is 400℃, the oxidation atmosphere is air, and the oxidation time is 60min;

[0056] Step 5: Perform high-temperature reduction treatment on the oxidized powder prepared in Step 4, the reduction temperature is 600℃, and the reduction time is 60min under the reduction atmosphere;

[0057] Step 6: Perform crushing and screening treatment on the reduced powder prepared in Step 5 to obtain the final target product.

[0058] The above powder is sintered, and the pore structure in the original particles is still maintained after sintering. Test results show that the green strength is 8.5 MPa, the powder flowability is 30s / 50g, and the powder bulk density is 2.6g / cm 3 .

[0059] Example 5

[0060] The copper-tin alloy powder is prepared according to the following steps:

[0061] Step 1: Mix the copper powder with the copper-tin alloy powder to obtain a mixed powder with a tin content of 10wt%, and the particle size of the mixed powder is 10µm;

[0062] Step 2: Prepare the glue by dissolving xanthan gum in water, and the mass ratio of xanthan gum is 3%;

[0063] Step 3: Granulate the mixed powder with the glue prepared in Step 2 to obtain a granulated powder with a particle size of 250µm;

[0064] Step 4: The granulated powder prepared in step 3 is subjected to high-temperature oxidation treatment, the oxidation temperature is 400℃, the oxidation atmosphere is air, and the oxidation time is 60 min;

[0065] Step 5: The oxidized powder prepared in step 4 is subjected to high-temperature reduction treatment, the reduction temperature is 600℃, and the reduction time is 60 min under the reduction atmosphere;

[0066] Step 6: The reduced powder prepared in step 5 is subjected to crushing and screening treatment to obtain the final target product.

[0067] The above powder is sintered, and the pore structure in the original granules is still maintained after sintering. Test results show that the green strength is 12 MPa, the powder flowability is 36s / 50g, and the powder bulk density is 1.8g / cm 3 .

Claims

1. A method for producing a copper-tin alloy powder, characterized by The method comprises the following steps: Step 1: mixing copper powder with copper-tin alloy powder to obtain mixed powder with tin content of 10wt%; Step 2: glue preparation, dissolving polymer binder in water to obtain glue with polymer binder mass fraction of 1-10%; Step 3: granulating the mixed powder with the glue prepared in step 2 to obtain granulated powder with particle size less than 250µm; Step 4: high-temperature oxidation treatment of the granulated powder prepared in step 3, oxidation temperature being 300-600℃, oxidation atmosphere being air, and oxidation time being 20-120min; Step 5: high-temperature reduction treatment of the oxidized powder prepared in step 4, reduction temperature being 400-800℃, and reduction time being 30-120min under reduction atmosphere; Step 6: crushing and screening treatment of the reduced powder prepared in step 5 to obtain the final target product, the copper-tin alloy powder being spherical and having 3-level holes, the 3-level holes being specifically as follows: first-level hole size being 20-200µm; second-level hole size being 5-30µm; and third-level hole size being 0.1-5µm. The particle size of the mixed powder in step 1 is 10-60µm. Third order pore size 0.5-10 pm, loose bulk density 1.8-2.9 g / cm3 3 .

2. The method of producing a copper-tin alloy powder according to claim 1, characterized by The polymer binder in step 2 is polyvinyl alcohol, cellulose or xanthan gum.

3. The method of producing a copper-tin alloy powder according to claim 1, characterized by The particle size of the granulated powder in step 3 is 10-250µm.

4. The method of producing a copper-tin alloy powder according to claim 1, characterized by The oxidation temperature in step 4 is 400-550℃.

5. The method of producing a copper-tin alloy powder according to claim 1, characterized by The reduction temperature in step 5 is 500-700℃, and the reduction atmosphere is hydrogen, ammonia decomposition gas or carbon monoxide.

6. The method of producing a copper-tin alloy powder according to claim 1, characterized by The product is prepared by the method of any one of claims 1-6.

7. A copper-tin alloy powder, characterized by, ​

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