Rotary expansible chamber devices – With wear surface treatment or integrally plated wear layer
Patent
1995-01-27
1996-11-12
Vrablik, John J.
Rotary expansible chamber devices
With wear surface treatment or integrally plated wear layer
418179, 428650, 428652, 428680, F04C 18344, F04C 18356, B32B 1504, B32B 1520
Patent
active
055733905
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to sliding material. More particularly, the present invention relates to sliding material used for the substrate of such sliding members as the vane, scroll, piston and the like of a cooler-compressor, said substrate consisting of aluminum-alloy being subjected to surface treatment.
PRIOR ART
It is known that the aluminum-alloy is used for the above described sliding material to reduce weight, and, further, surface treatment is carried out for enhancing its sliding properties.
As a prior art of surface treatment for enhancing the seizure-resistance of a scroll made of aluminum-alloy, Japanese Unexamined Patent Publication No. Sho 62-199,982 refers to electroless Ni plating, ceramic dispersion-plating, ceramic flame-plating and the like, as prior art. Allegedly, the electroless Ni-B plating is superior to these prior arts because of good wear-resistance and distribution of coating thickness.
Japanese Unexamined Patent Publication No. Sho 58-193,355, which belongs to a prior art of the surface treatment, is related to the plating method in which the electroless Ni-P plating is applied on the surface of a work piece made of steel and, subsequently, electroless composite plating is carried out with co-deposition of ultra-hard fine particles. It teaches that flash plating by the electroless Ni-P plating acts as a precursor of the composite plating and improves the throwing power of the plating.
In addition, Japanese Examined Patent Publication No. Hei 2-50,993 is related to the improvement of corrosion-resistance of coating, in which an Ni-W-P plating layer is formed on an Ni-P plating layer. Allegedly, no drawbacks of each of these plating layers appear, but, the coating provided exhibits improved corrosion-resistance, hardness, wear-resistance, and resistance to embrittlement, when these layers are used in a combination.
Since the hardness of Ni-B plating is in the range of Hv=700.about.900, while the hardness of aluminum alloy is in the range of Hv=100.about.140, the difference in hardness between the plating coating and the aluminum-alloy, which is a substrate, is very great. In addition, since the internal tensional stress acts on the Ni-B plating coating, peeling is likely to occur. Because of this property of the Ni-B plating coating, when the Ni-B plating coating is directly applied on the surface of aluminum alloy, and is exposed to the reciprocating load or impact force from the opposite material, chipping or peeling is likely to occur. This exerts a detrimental influence upon the sliding properties of Ni-B plating. Thin Zn plating is also carried out as a pre-treatment prior to the application of Ni-B plating. However in this case also, the problems as described above occur.
When Ni-B plating is applied on the surface of aluminum-alloy directly or with an intermediary of the Zn intermediate plating layer, Al or Zn dissolves from the work piece into the Ni-B plating liquid and is then incorporated into the Ni-B plating coating. Al and Zn exert a detrimental influence in the form of impurities and result in decomposition of the plating liquid and hence impairment of productivity.
DISCLOSURE OF INVENTION
It is, therefore, an object of the present invention to discourage chipping and peeling of the electroless Ni-B plating coating formed on the surface of aluminum-alloy, and to provide a sliding material whose electroless plating liquid is not detrimentally influenced by the dissolution of components of the mother material.
The sliding material according to the present invention is characterized by the provision of an electroless Ni-B plating coating formed of the surface of aluminum alloy via the intermediary of an electroless Ni-P plating coating.
The Ni-P plating is known itself and is used as the underlying plating layer in the above referred Japanese Unexamined Patent Publication No. sho 58-193,355 and Japanese Examined Patent Publication No. Hei 2-50,933. The present invention is different from the these prior arts in the point that the Ni-P plat
REFERENCES:
patent: 5269838 (1993-12-01), Inoue et al.
Kondo Hirokazu
Muramatsu Shogo
Takeuchi Katsuhiro
Toyama Yoichiro
Surtec Kariya Co., Ltd.
Taiho Kogyo Co., Ltd
Vrablik John J.
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