Composited cast member, iron-based porous substance for composited cast members, and pressure casing processes for producing the same, constituent member of compressors provided with composited cast members and the compressors

Abstract

A pressure casing includes a composited cast member. The composited cast member includes an iron-based porous substance whose major component is Fe and which has a large number of pores, and a cast-wrapping member whose major component is a light metal and which cast-wraps a part of the iron-based porous substance at least. The iron-based porous substance includes a connector disposed adjacent to a boundary between the iron-based porous substance and the cast-wrapping member and exhibiting a larger porosity, and a high-strength reinforcer disposed in the iron-based porous substance free from the connector and exhibiting a smaller porosity. The connector is impregnated with the cast-wrapping member, and solidifies therewith, thereby firmly bonding the iron-based porous substance and the cast-wrapping member in the composited cast member. The pressure casing secures strength with the reinforcer, and secures adhesiveness with the connector.

1 . A composited cast member, comprising: 
 an iron-based porous substance comprising iron (Fe), and having a large number of pores; and    a cast-wrapping member comprising a metal whose major component is at least one member selected from the group consisting of aluminum (Al) and magnesium (Mg), and cast-wrapping a part of the iron-based porous substance at least;    the iron-based porous substance further comprising a connector disposed adjacent to a boundary between the iron-based porous substance and the cast-wrapping member and exhibiting a predetermined porosity, and a high-strength reinforcer disposed in the iron-based porous substance free from the connector and exhibiting a porosity smaller than that of the connector; and    the connector being impregnated with the cast-wrapping member, and solidifying therewith, thereby firmly bonding the iron-based porous substance and the cast-wrapping member.    
   
   
       2 . The composited cast member set forth in  claim 1 , wherein the connector exhibits a porosity of from 25 to 50% by volume, and the reinforcer exhibits a porosity of from 5 to 25% by volume.  
   
   
       3 . The composited cast member set forth in  claim 1 , wherein the porosity decreases from large to small in a gradient manner from the connector to the reinforcer.  
   
   
       4 . The composited cast member set forth in  claim 1 , wherein the iron-based porous substance comprises an iron-based porous sintered substance which is made by sintering a powder compact formed by pressing a ferrous powder whose major component is Fe.  
   
   
       5 . The composited cast member set forth in  claim 1 , wherein the iron-based porous substance is formed as a cylinder-shaped member in which the connector is disposed on an outer peripheral side and the reinforcer is disposed on an inner peripheral side, and the reinforcer is subjected to an internal pressure.  
   
   
       6 . A process for producing the composited cast member set forth in  claim 1 , the process comprising the steps of: 
 impregnating an iron-based porous substance with a molten metal for making a cast-wrapping member by pouring the molten meal into a cavity of a mold in which the iron-based porous substance is disposed, the iron-based porous substance comprising a connector whose major component is Fe, having a large number of pores and exhibiting a predetermined porosity, and a high-strength reinforcer exhibiting a porosity smaller than that of the connector, the molten metal comprising a metal whose major component is at least one member selected from the group consisting of Al and Mg, thereby impregnating the iron-based porous substance with the molten metal inward from the connector into the iron-based porous substance; and    solidifying the molten metal by cooling after the impregnating step;    thereby producing a composited cast member in which the iron-based porous substance is firmly bonded to the cast-wrapping member at the connector, and is cast-wrapped by the cast-wrapping member.    
   
   
       7 . An iron-based porous substance used in the composited cast member set forth in  claim 1 , the iron-based porous substance comprising Fe, having a large number of pores and being cast-wrapped by a cast-wrapping member comprising a metal whose major component is at least one member selected from the group consisting of Al and Mg, and the iron-based porous substance further comprising: 
 a connector disposed adjacent to a potential boundary between the iron-based porous substance and the cast-wrapping member, and exhibiting a predetermined porosity; and    a high-strength reinforcer disposed in the iron-based porous substance free from the connector, and exhibiting a porosity smaller than that of the connector.    
   
   
       8 . A process for producing the iron-based porous substance set forth in  claim 7 , the process comprising the steps of: 
 laminating a first powder compact exhibiting a predetermined porosity, the first powder compact formed by pressing a ferrous powder whose major component is Fe, on a second powder compact exhibiting a smaller porosity than that of the first powder compact, the second powder compact formed by pressing the ferrous powder, thereby making a laminated powder compact; and    sintering the laminated powder compact, thereby producing an iron-based porous sintered substance comprising a connector formed of the first powder compact and exhibiting a predetermined porosity, and a high-strength reinforcer formed of the second powder compact and exhibiting a smaller porosity than that of the connector.    
   
   
       9 . A process for producing the iron-based porous substance set forth in  claim 7 , the process comprising the steps of: 
 producing a powder compact by pressing a first powdery portion comprising a mixture powder of a ferrous powder whose major component is Fe and a pore-making material forming pores by disappearing when being heated at temperatures of a sintering temperature of the ferrous powder or less, and a second powdery portion comprising the ferrous powder more than the first powdery portion does and the pore-making material less than the first powdery portion does; and    sintering the powder compact, thereby producing an iron-based porous sintered substance in which the first powdery portion is turned into a connector exhibiting a predetermined porosity and the second powder portion is turned into a high-strength reinforcer exhibiting a smaller porosity than that of the connector.    
   
   
       10 . A pressure casing, at least a part of the pressure casing comprising a composited cast member, the composited cast member comprising: 
 an iron-based porous substance comprising Fe and having a large number of pores; and    a cast-wrapping member comprising a metal whose major component is at least one member selected from the group consisting of Al and Mg and cast-wrapping a part of the iron-based porous substance at least;    the iron-based porous substance further comprising a connector disposed adjacent to a boundary between the iron-based porous substance and the cast-wrapping member and exhibiting a predetermined porosity, and a high-strength reinforcer disposed in the iron-based porous substance free from the connector and exhibiting a porosity smaller than that of the connector; and    the connector being impregnated with the cast-wrapping member, and solidifying therewith, thereby firmly bonding the iron-based porous substance and the cast-wrapping member.    
   
   
       11 . The pressure casing set forth in  claim 10 , wherein the iron-based porous substance and the composited cast member are formed as a cylinder-shaped member, respectively, and the pressure casing is subjected to an internal pressure exerted from an inner peripheral side of the composited cast member.  
   
   
       12 . The pressure casing set forth in  claim 11 , wherein the iron-based porous substance comprises the connector disposed on an outer peripheral side, and the reinforcer disposed on an inner peripheral side; and 
 the composited cast member comprises the iron-based porous substance, and the cast-wrapping member cast-wrapping around the connector of the iron-based porous substance.    
   
   
       13 . A process for producing the pressure casing set forth in  claim 10 , comprising the steps of: 
 impregnating an iron-based porous substance with a molten metal for making a cast-wrapping member by pouring the molten meal into a cavity of a mold in which the iron-based porous substance is disposed, the iron-based porous substance comprising a connector whose major component is Fe, having a large number of pores and exhibiting a predetermined porosity, and a high-strength reinforcer exhibiting a porosity smaller than that of the connector, the molten metal comprising a metal whose major component is at least one member selected from the group consisting of Al and Mg, thereby impregnating the iron-based porous substance with the molten metal inward from the connector into the iron-based porous substance; and    solidifying the molten metal by cooling after the impregnating step;    thereby producing a pressure casing partially provided with a composited cast member in which the iron-based porous substance is firmly bonded to the cast-wrapping member at the connector, and is cast-wrapped by the cast-wrapping member.    
   
   
       14 . A constituent member of compressors which compress an intake working fluid and discharge the highly pressurized working fluid, at least a part of the constituent member comprising: 
 a composited cast member comprising: 
 an iron-based porous substance comprising Fe and having a large number of pores; and  
 a cast-wrapping member comprising a metal whose major component is at least one member selected from the group consisting of Al and Mg, and cast-wrapping a part of the iron-based porous substance at least;  
 the iron-based porous substance further comprising a connector disposed adjacent to a boundary between the iron-based porous substance and the cast-wrapping member and exhibiting a predetermined porosity, and a high-strength reinforcer disposed in the iron-based porous substance free from the connector and exhibiting a porosity smaller than that of the connector, the connector being impregnated with the cast-wrapping member and solidifying therewith, thereby firmly bonding the iron-based porous substance and the cast-wrapping member in the composited cast member.  
   
   
   
       15 . A compressor, comprising: 
 the constituent member set forth in  claim 14.