JPH0772329B2 - Corrosion resistant Fe-based sintered parts - Google Patents

Description

Detailed Description of the Invention a. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe-based metal powder sintered alloy component which is excellent in corrosion resistance, particularly corrosion resistance to alcohol such as methanol, and is inexpensive.

B. 2. Description of the Related Art Recently, for example, mainly in the automobile industry, alternative fuels obtained by adding alcohol such as methanol to gasoline have been studied. In this case, if alcohol such as methanol is added to gasoline, OH from alcohol contained in the fuel
The action of ions causes a problem of corrosion of Fe-based alloy parts. These parts may be manufactured from ingots by machining or as sintered parts by powder metallurgy. In any case, when using methanol-added gasoline fuel, parts that come into contact with the fuel, such as a fuel pump Corrosion-resistant products are required for the rotors and cams, and stainless steel parts are used. For example, Japanese Examined Patent Publication No. 1-15581.
Generally, addition of Ni, Cr, etc. to Fe-based materials such as stainless steel is effective for improving corrosion resistance.

C. Problems to be Solved by the Invention However, when stainless steel parts are manufactured with ingot, the cost is high for mass production because the machinability of stainless steel is poor and burr treatment during processing is difficult. There is.

In the case of sintered parts suitable for mass production, general sintered steels that are easy to sinter, such as Fe-C, Fe-Cu-C, and Fe-Ni-Cu-C, are 100% gasoline, but methanol is not a problem. If added, it cannot be used because rust (corrosion) occurs. Also, in the case of sintered stainless steel, although it is satisfactory in rust prevention,
The dimensional accuracy when sintered is poor, the raw material is expensive, and since it contains Cr, which is easy to oxidize, a reducing gas such as H ₂ gas, a special sintering atmosphere such as vacuum is required, and there is a disadvantage that the cost becomes high. .

D. Means for Solving the Problems The present invention is inferior in corrosion resistance to some extent as compared with sintered stainless steel, but has sufficient corrosion resistance to alcohol such as methanol and the production cost of conventional sintered stainless steel parts is low. It is an object of the present invention to provide a corrosion-resistant sintered part that eliminates high drawbacks.

As a result of conducting a search for various materials, the present inventors found that Fe
The present invention has been made by discovering that an alloy containing no alloying elements other than inevitable impurities, such as Cu, Cr, and Mo, in the -Ni-C sintered alloy comes to the above object.

That is, the present invention is Ni ...... 2.0 to 10.0% C ...... 0.2 to 1.2% Fe ...... Residue and other unavoidable impurities ...... 2% or less, however, unavoidable impurities are usually contained in the above Fe, Ni, C raw material powder Mn, S,
Mo, Cr, V, Cu, B, etc., which indicate P, O, N, etc. and are positively added as alloying elements in sintered steel, are sintered parts having a composition that does not include.

The sintered part of the present invention contains Ni, and since Ni diffuses into Fe during sintering, it has good corrosion resistance to a gasoline fuel added with methanol or the like. Further, as a sintered material, the dimensional change during sintering is small and the dimensional accuracy is excellent. Furthermore, the composition is simple and the material cost is low, and since it does not contain Cr, it can be easily sintered in a normal neutral or reducing atmosphere, and the manufacturing cost is low.

In the present invention, when Ni is less than 2.0%, there is no effect on the corrosion resistance, and when Ni of 10% or more is used, the material cost increases. Further, it is necessary to contain C in order to impart wear resistance as a sintered part. It is necessary to contain Mo, Cr, V, Cu, B, which are alloying elements other than unavoidable impurities such as Mn, S, P, O, and N that are usually contained in raw material powders such as Fe, Ni, and C. Is. The total amount of unavoidable impurity elements is limited to the content in ordinary raw material powders. In this case, the normal raw material powder refers to reduced iron powder and atomized iron powder for Fe, carbonyl nickel powder for Ni, and natural or artificial graphite powder for powder metallurgy.

E. Example A sintered part having the composition shown in Table 1 and an outer diameter of 15 mm and a thickness of 5 mm was produced.

The above various metal powder sintered materials were mixed according to their respective compositions, preformed by a press to have a density of 6.8 to 6.9 g / cm, and sintered at 1130 ° C. for 30 minutes in an RX gas atmosphere.

Samples (A) gasoline (100%), (B) gasoline + methanol (5%), (C) gasoline + methanol (10%)
%) Was immersed in three types of fuel for 3200 hours, and the rust generation state was observed.

The results are shown in Table 2.

From the above results, it is understood that the Fe-based sintered component of the present invention has sufficient corrosion resistance to alcohol such as methanol.

F. Effects of the Invention As described in detail above, the Fe-based sintered parts of the present invention are suitable for mass production as compared with ingot materials, and Ni-based
It has sufficient corrosion resistance to a fuel containing alcohol such as methanol by simply adding. In addition, the material is cheaper than stainless steel sintered parts and it does not contain Cr, so it can be sintered in normal atmospheric gas, and the dimensional accuracy after sintering is good, and the manufacturing cost is low. Therefore, it is very effective for use as a Fe-based sintered component in a portion in contact with an alcohol-containing petroleum product such as methanol-added gasoline, for example, a component such as a rotor, a cam or a side plate of a fuel pump.

Claims (2)

[Claims] 1. A Fe-based metal powder sintering material used for a machine part that is in contact with a liquid containing alcohol such as methanol, Ni: 2.0 to 10.0% C: 0.2 to 1.2% Fe: Residual and other inevitable Impurities: Corrosion-resistant Fe-based sintered parts characterized by being composed of 2.0% or less of components. 2. The corrosion-resistant Fe-based sintered component according to claim 1, which is used for a fuel pump of an automobile.