JPS5843459B2 - Aluminum sintered alloy member and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum sintered alloy member and a method for manufacturing the same.

Traditionally, sintered alloys with aluminum as the main component have advantages such as corrosion resistance and light weight.
There are problems such as insufficient mechanical strength and sintering conditions are set relatively far apart, and satisfactory results are not necessarily obtained.

This invention has succeeded in significantly improving these conventional problems. In particular, by incorporating a boron compound such as boron sesquioxide, the mechanical strength of the sintered alloy member can be improved. Moreover, the sintered alloy can be sintered in the atmosphere to obtain a sintered alloy.

That is, the weight ratio is 0.5-6% copper and 0.6% magnesium.
2-2 Hiroshi silicon 0.2-2%, boron sesquioxide (B20
3), Sodium tetraborate (Na2B407), colemanite which has been sintered to remove crystal water, pandermite (both Ca2B, 01), polonatrocalcite (C
The present invention provides an aluminum sintered alloy member consisting of 0.5 to 6% of a boron compound, which is a mixture of one or more selected from aB407 and NaBO2, and the balance aluminum, as well as a manufacturing method.

In this invention, the aluminum sintered alloy member refers to mechanical parts,
Refers to structural members, jigs, metal fittings, etc., and does not include sliding members that primarily slide.

According to experiments conducted by the present inventors, especially when used as a sliding member, in the case of Al-Cu-Mg-8i based sintered alloy, unless the amount of Si is at least 5 weight φ or more, sliding becomes difficult. It has been confirmed that the anti-seizure and load-bearing properties of this material as a moving member are insufficient, and it is almost impossible to put it into practical use.

In this invention, the boronate compound is boronate (B203)
, sand (Na2B407.10H20), colemanite (Ca2B601.-5H20), pandelmite (
Ca2B601, .3H20), boronatrocalcite (CaB407.NaBO2.6H20), etc. are used, but borium sesquioxide is particularly effective, followed by borax.

When using borate containing water of crystallization, it is important to use one that has all the water of crystallization removed.

That is, for example, borax (Na2B40710H20
), bake it at 400℃ to remove crystal water,
Used as sodium tetrabolate (Na2B407).

Products that contain water of crystallization will not be effective unless all of this water is removed before use.

The boronic compound has the effect of improving the sinterability of the green compact and significantly improving the mechanical strength of the sintered alloy member.

According to the inventor's experiments, the effect of boron sesquioxide is already visible when it is added at around 0.5 weight φ, and it also contributes to improving mechanical strength at around 2 weight φ, compared to the one without additive. It was confirmed that the strength increased approximately twice as much.

If a larger amount than 2 weights is added, the strength begins to decrease, and when around 10 weights is added, the strength becomes comparable to that of an alloy without additives.

The boron compounds mentioned above have the effect of dissolving metal oxides and preventing the oxidation of the components during compact sintering, so they improve the sinterability of aluminum powder, especially in the atmosphere. It is thought that this makes sintering possible, but an even greater effect is due to the use of copper and magnesium, or compounds of magnesium and silicon (M
By promoting the diffusion of gSi2) into aluminum and creating a uniform alloy composition, the present inventor confirmed this fact and the effect of analysis using an X-ray microanalyzer.

In other words, in alloys that do not contain boronate compounds,
For example, the copper component is largely distributed around grain boundaries or voids in the sintered alloy, but by adding this compound, the distribution of copper becomes extremely uniform, confirming that the diffusion into the aluminum is proceeding smoothly. It was done.

Therefore, it can be considered that the sintered body was highly alloyed and the strength as a sintered alloy member was significantly improved.

However, the addition of this boron compound tends to increase the porosity of the sintered body, and this tendency is particularly significant when the amount added exceeds 2 weight φ.

As mentioned above, the reason why the strength decreases as a peak with 2 weight predominant boron compounds is due to the progress of diffusion of components in the sintered alloy.
Although it has the advantage of being highly alloyed,
This increase in porosity has the disadvantage of a decrease in strength, and this is simply because the balance between the two has been disrupted.

When a sintered alloy is impregnated with lubricating oil to impart self-lubricating properties and is used as a sliding member, the porosity of the alloy is an important factor, but the present invention does not require porosity.

It is desired that the strength is as high as possible, and from this point of view, the boron compound is desirably 1 to 4 weights out of 0.5 to 6 weights.

The copper component contributes to improving the strength of the alloy, but in this invention, it has little effect if it is less than 0.5 weight, and if it is added in excess of 6 weight, it tends to make the material brittle. The amount is preferably Q, 5 to 6 weight kesa.

The magnesium component not only coexists with copper and contributes to improving the mechanical strength of the alloy, but also partially diffuses in the form of silicon and MgSi2 and contributes to the age hardenability of the aluminum sintered alloy.

In this invention, if less than 0.2 weight of rice cake is added, there is almost no effect, and if it is added in excess of 2 weight of rice cake, it will warp, resulting in a decrease in strength, and the sinterability will also deteriorate.

Therefore, it is desirable that the amount of magnesium be 0.2 to 2% by weight.

Silicon is contained in aluminum as an impurity, but it is limited to more than 2 parts by weight at most.

In particular, it is desirable that the weight φ is 0.2 to 0.8.

As already mentioned, silicon is magnesium and MgSi
Silicon forms an intermetallic compound of type 2, which contributes to the age hardenability of the aluminum sintered alloy, but most of the silicon exists in the alloy in the form of a dispersed silicon.

Therefore, it is easy to damage the homogeneity of the alloy, so unless it is used as a sliding member that requires seizure resistance, etc.
It is not beneficial to disperse silicon in large amounts.

When obtaining the sintered alloy member of the present invention having the above-mentioned composition, a suitable molding pressure is 1 to 6 tons/cd, particularly 2 to 5 tons/cd.

When the molding pressure is 2 tons/cd, the theoretical density ratio exceeds 90%.

It is appropriate that the sintering temperature is 550 to 640°C, which is below the melting point of aluminum, and the sintering time is 5 to 60 minutes.

The sintering atmosphere may be neutral or reducing, but the feature of this invention is that sintering can be performed in the air, and there is no significant difference in the mechanical strength of the obtained sintered body depending on the atmosphere. This means that it is not recognized.

Moreover, the strength is significantly higher than that of sintered alloys that do not contain boron compounds.

In air sintering, there is no benefit in taking too long a sintering time.

It is desirable to proceed with the sintering quickly in a furnace adjusted to the predetermined temperature mentioned above, and the mechanical strength of the sintered body reaches approximately the maximum strength after sintering time of about 30 minutes.

The outer surface of the obtained sintered body is almost comparable to that of one sintered under controlled atmosphere.

In this way, the weight ratio is 0.5 to 6% copper and 0.5% magnesium.
2-2 Hiroshi Silicon 0.2-2 Hiroshi Boron Compound 0.5-6%
The mechanical strength of the sintered alloy member, which is made of aluminum with the remainder being aluminum, has significantly increased mechanical strength, making it ideal for applications such as mechanical parts and structural parts.

In particular, the boron compound in the component not only improves sinterability and mechanical strength, but also contributes to the age hardenability of the sintered alloy, making the sintered alloy member even stronger. .

A few examples will be described below.

Example 1 4 weight φ of electrolytic copper powder passing through 200 meshes, 0.5 weight cup of magnesium powder passing through 200 meshes, 0.8 weight cup of silicon powder passing through 250 meshes, and sesquioxide passing through 200 meshes 2 weight rice cake with borosin,
The remainder is atomized aluminum powder that passes through 250 meshes, and a small amount of lubricant such as lauryl alcohol (2 parts by weight per 100 parts by weight of alloy powder) is uniformly mixed with this, and the resulting mixed powder is placed in a mold. After compacting at a molding pressure of 4 tons/cd, the powder was removed from the mold and fired in the atmosphere at a temperature of 580±10° C. for 10 minutes.

The sintered alloy thus obtained was then heat treated under the following temperature conditions.

b) After holding at 505±5°C for 30 minutes mouth) water cooling, c) After keeping at 160±5°C for 18 hours, let it cool.

Example 2 A sintered alloy was obtained in the same manner as in Example 2 except that the molding pressure was 6 tons/cd.

This was then heat treated under the same temperature conditions as in Example (2).

Example ■ In Example ■, 5 sand was used instead of boron sesquioxide.
A sintered alloy was obtained in the same manner using sodium tetraborate (Na2B40□) powder obtained by baking at 00°C to completely remove crystallization water.

This was then heat-treated under the same temperature conditions as in Example (2).

Comparative Example 1 A sintered alloy was obtained in the same manner as in Example (2) except that boron sesquioxide was not added and the remainder was aluminum powder.

This was then heat-treated under the same temperature conditions as in Example (2).

Comparative Example 2 In Example ■, no boron sesquioxide was added, the remainder was aluminum powder, and the molding pressure was 6 tons/c.
A sintered alloy was obtained as rA in the same manner as below.

This was then heat-treated under the same temperature conditions as in Example (2).

The table shows the mechanical strength of the sintered alloys according to each of the above examples and comparative examples.

From the above table, it can be seen that the mechanical strength of the aluminum sintered alloy members of Examples 1 and 2 is significantly increased compared to Comparative Examples 1 and 2.

Depending on the intended use of the sintered alloy member, a sintering method in which the green compact is heated while being pressurized in a mold, in addition to the method described in the above embodiment, may be used to achieve even higher density and higher strength. A sintered metal member can be obtained.

Depending on the purpose of use, a sintered alloy member with even higher density and higher strength can be obtained by adopting a sintering method of heating while pressurizing in a mold.

Claims (1)

[Claims] 1. Copper 0.5-6%, magnesium 0.2-2% by weight
A mixture of one or more selected from the group consisting of 0.2 to 2% borosilicon, boron sesquioxide, sodium tetraborate, colemanite, pandermite, and boronatrocalcite which have been calcined to remove crystal water. boron compound 0.5~6φ,
And an aluminum sintered metal member for mechanical parts and structural members, characterized in that the remainder is made of aluminum. 2 Copper powder 0.5-6% by weight, magnesium powder 0
．． 2% to 2%, silicon powder 0.2% to 2%, boron sesquioxide, sodium tetraborate, a type selected from colemanite, pandermite, and boronatrocalcite, which have been calcined to remove crystal water, or 0.5-6% boron compound powder, which is a mixture of two or more types, and the balance aluminum powder were uniformly mixed together with a small amount of lubricant, and the obtained mixed powder was compacted at a compacting pressure of 1-6 tons/cd. A method for producing an aluminum sintered alloy member for mechanical parts and structural members, characterized in that the molded product is then sintered at a temperature of 550 to 640°C for 5 to 60 minutes.