Process for producing aluminum composite material

Abstract

The present invention is such that it is an assignment to be solved to provide a process for producing aluminum composite material in which an iron sintered body of much higher adhesion is cast-in inserted with aluminum. A process according to the present invention for producing aluminum composite material is characterized in that it has: a preform molding step of molding a porous iron sintered-material preform by molding an iron powder so that an occupational volumetric fraction becomes from 50% or more to 70% or less, and then by sintering the iron powder, thereby molding a porous iron sintered material preform; and a composite-material forming step of placing said preform in a casting die whose die temperature is from 200° C. or more to 400° C. or less, the preform being preheated at a preheating temperature of from 300° C. or more to 400° C. or less in vacuum, in an inert-gas atmosphere, in a reducing-gas atmosphere, or in a mixture-gas atmosphere of inert gas and reducing gas, and then carrying out casting by means of impregnating the preform with molten aluminum or aluminum alloy by pressurizing the molten aluminum or aluminum alloy by a 2-stage pressurizing method, the 2-state pressurizing method comprising a first pressurizing stage and a second pressurizing stage.

1 . A process for producing aluminum composite material, the process being characterized in that it has:
 a preform molding step of molding a porous iron sintered-material preform by molding an iron powder so that an occupational volumetric fraction becomes from 50% or more to 70% or less, and then by sintering the iron powder at a sintering temperature of from 1,100° C. or more to 1,300° C. or less in vacuum, in an inert-gas atmosphere, in a reducing-gas atmosphere, or in a mixture-gas atmosphere of inert gas and reducing gas, thereby molding a porous iron sintered material preform; and   a composite-material forming step of placing said preform in a casting die whose die temperature is from 200° C. or more to 400° C. or less, the preform being preheated at a preheating temperature of from 300° C. or more to 400° C. or less in vacuum, in an inert-gas atmosphere, in a reducing-gas atmosphere, or in a mixture-gas atmosphere of inert gas and reducing gas, and then carrying out casting by means of impregnating the preform with molten aluminum or aluminum alloy by pressurizing the molten aluminum or aluminum alloy by a 2-stage pressurizing method, the 2-stage pressurizing method comprising a first pressurizing stage in which the molten aluminum or aluminum alloy is pressurized at a lower pressure and a second pressurizing stage which follows the first pressurizing stage and in which the molten aluminum or aluminum alloy is pressurized at a higher pressure than the pressure in the first pressurizing stage.   
   
   
       2 . The process for producing aluminum composite material set forth in  claim 1 , wherein said occupational volumetric fraction is from 55% or more to 65% or less. 
   
   
       3 . The process for producing aluminum composite material set forth in  claim 1 , wherein said preheating temperature is from 350° C. or more to 400° C. or less. 
   
   
       4 . The process for producing aluminum composite material set forth in  claim 1 , wherein said die temperature is from 200° C. or more to 250° C. or less. 
   
   
       5 . The process for producing aluminum composite material set forth in  claim 1 , said 2-stage pressurizing method comprises: a first pressurizing stage in which the molten aluminum or aluminum alloy is pressurized at a lower pressure of from 20 MPa or more to 30 MPa or less for from 5 seconds or more to 15 seconds or less; and a second pressurizing stage which follows the first pressurizing method and in which the molten aluminum or aluminum alloy is pressurized at a higher pressure of from 70 MPa or more to 100 MPa or less for from 3 minutes or more to 5 minutes or less. 
   
   
       6 . The process for producing aluminum composite material set forth in  claim 1 , wherein said iron powder is such that the particle diameter is from 45 μm or more to 200 μm or less. 
   
   
       7 . The process for producing aluminum composite material set forth in  claim 1 , wherein said die temperature of the casting die is said preform preheating temperature or less. 
   
   
       8 . A process for producing aluminum composite material, the process being characterized in that it has:
 a composite-material forming step of placing a porous iron sintered-material preform in a casting die whose die temperature is from 200° C. or more to 400° C. or less, porous iron sintered-material preform which is preheated at a preheating temperature of from 300° C. or more to 400° C. or less in vacuum, in an inert-gas atmosphere, in   a reducing-gas atmosphere, or in a mixture-gas atmosphere of inert gas and reducing gas, and porous iron sintered-material preform in which an occupational volumetric fraction of iron powder is from 50% or more to 70% or less and then carrying out casting by means of impregnating the porous iron sintered-material preform with molten aluminum or aluminum alloy by pressurizing the molten aluminum or aluminum alloy with a 2-stage pressurizing method, the 2-stage pressurizing method comprising a first pressurizing stage in which the molten aluminum or aluminum alloy is pressurized at a lower pressure and a second pressurizing stage which follows the first pressurizing stage and in which the molten aluminum or aluminum alloy is pressurized at a higher pressure than the pressure in the first pressurizing stage.   
   
   
       9 . The process for producing aluminum composite material set forth in  claim 1 , wherein:
 said occupational volumetric fraction is from 55% or more to 65% or less;   said preheating temperature is from 350° C. or more to 400° C. or less;   said die temperature is from 200° C. or more to 250° C. or less;   said iron powder is such that the particle diameter is from 45 μm or more to 200 μm or less; and   said die temperature of the casting die is said preform preheating temperature or less.