Cu-based sintered alloy and method for producing the same and bearing used for motor for pure water

Abstract

A sintered alloy has prolonged life span in a state where it is in contact with pure water. A bearing 5 is made of a Cu-based sintered alloy 51 having excellent corrosion resistance against liquid including sulfur or its compounds. A tetrafluoroethylene resin layer 53 is provided at the external surface of the sintered alloy 51. The Cu-based sintered alloy 51 is covered with a tetrafluoroethylene resin layer 53 having corrosion resistance, so that it is possible to secure high corrosion resistance even when the sintered alloy 51 is in contact with ionized pure water. It is also possible to provide a sintered alloy having prolonged life span while it is in contact with pure water.

What is claimed is:  
     
         1 . A Cu-based sintered alloy containing, by mass percent, Ni: about 5 to about 25%, P: about 0.1 to about 0.9%, and C: about 1 to about 7%, with a fluororesin layer provided in its external surface.  
     
     
         2 . The Cu-based sintered alloy according to  claim 1 , wherein the fluororesin comprises tetrafluoroethylene resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer or tetrafluoroethylene-hexafluoropropylene copolymer.  
     
     
         3 . The Cu-based sintered alloy according to  claim 1 , wherein the thickness of the fluororesin layer is about 1 to about 40 μm.  
     
     
         4 . A bearing used for a motor for pure water, wherein the bearing is made of the Cu-based sintered alloy according to  claim 1 .  
     
     
         5 . A method for producing a Cu-based sintered alloy, wherein fluororesin is impregnated in the Cu-based sintered alloy which contains, by mass percent, Ni: about 5 to about 25%, P: about 0.1 to about 0.9%, and C: about 1 to about 7%.  
     
     
         6 . The method for producing the Cu-based sintered alloy according to  claim 5 , wherein the open porosity of Cu-based sintered alloy before impregnation of fluororesin is about 2 to about 30%.  
     
     
         7 . The method for producing the Cu-based sintered alloy according to  claim 5 , wherein the fluororesin comprises tetrafluoroethylene resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer or tetrafluoroethylene-hexafluoropropylene copolymer.  
     
     
         8 . A bearing used for a motor for pure water, wherein the bearing is made of the Cu-based sintered alloy according to  claim 5 .  
     
     
         9 . The method for producing the Cu-based sintered alloy according to  claim 6 , wherein the fluororesin comprises tetrafluoroethylene resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer or tetrafluoroethylene-hexafluoropropylene copolymer.