Composite metal powder for sintered bearing, and sintered oil-retaining bearing

Abstract

Composite metal powder for sintered bearings, prepared by coating surface layers of particles of iron powder with 10 wt.% to less than 30 wt.% of copper based on the iron powder so that the particle size of the coated iron powder is at most 80 meshes, the content of the powder of at most 350 meshes is at most 30%, and the specific surface area of the powder is 450-750 cm<SP>2</SP>/g according to the subsieve sizer method. This metal powder can provide an oil-retaining bearing for motors, which is capable of providing a low gas-permeability without decreasing the oil content and which has a low and constant coefficient of friction, a high corrosion resistance, a high adaptability and a high durability, readily at a low cost.

Description

technical field [0001] The present invention relates to a composite metal powder for sintered bearings and oil-containing sintered bearings. This kind of bearings can be used as bearings for motors, etc., which is not only simple but also inexpensive, and can obtain low air permeability even without reducing the oil content, and has little friction and maintains In a constant state, it is an oil-impregnated bearing with strong corrosion resistance, excellent running-in performance and high durability. Background technique [0002] For the sintered body for bearings made of copper-coated iron powder, in No. 55-38019, it is proposed to use 30-60% copper-coated iron powder. Foil-like powder formed by layering the same metal or alloying metal. [0003] Japanese Patent Publication No. 7-54126 proposes that in order to improve the properties of sintered oil-impregnated bearings, it is considered necessary to lower the air permeability and add copper-graphite composite powder. In...

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Problems solved by technology

[0004] According to the above-mentioned Special Publication No. 55-38019, since the copper covering more than 30% is a necessary condition, a large amount of high-priced copper must be used, which has to increase the cost. The effect of the base is not fully exerted, so that the sliding performance as a bearing is poor, which is very disadvantageous

On the other hand, as disclosed in JP-A-3-166303, since a foil-shaped powder formed of the same metal or alloyed metal as the coating layer is added, the process is complicated and stable characteristics cannot be obtained, which is also disadvantageous. of

In particular, these disclosed high-performance bearing materials lack consideration for air permeability. Even after running-in, the oil pressure will escape from the oil hole on the sliding surface of the bearing. As an ideal oil-impregnated sintered bearing, it is difficult to obtain sliding close to fluid lubrication status, which is also very unfavorable

[0005] Regarding the above-mentioned situation of suppressing air permeability, although it is discussed in Japanese Patent Publication No. 7-54126, due to the addition of copper-graphite composite powder, the price of the powder has to become very high, and the sintered body The strength is reduced, which is very unfavorable

However, the above-mentioned JP-A-8-20836 discloses that 30 to 60% of copper-coated iron powder is used, and the process of sintering in a zinc atmosphere to make it adsorb zinc becomes a necessary condition, so even if excellent characteristics are obtained, it must be A large amount of copper is used, and since sintering in a zinc atmosphere is required, the number of man-hours increases rapidly, and the price has to be raised anyway.