Surface treatment method for powdered metal material

Abstract

To provide a method for surface treatment of a powdery metal material used for manufacture of harmonic structure metal in which a fine grain region and a coarse grain region are harmonically arranged. The method includes the steps of: using a blasting machine which ejects ejection powder with a compressed gas in a cabinet and causes the ejection powder to collide against an object to be collided and comprises dust collecting means; and performing blasting of causing a powdery metal material and a medium substance having hardness equal to or higher than that of the powdery metal material to collide with each other repeatedly, and exfoliate surface oxides from the powdery metal material and also form the fine grain region having a crystal grain diameter smaller than a crystal grain diameter of a center part in the vicinity of a surface of the powdery metal material.

1 . A method for surface treatment of a powdery metal material used for manufacture of harmonic structure metal in which a fine grain region and a coarse grain region are harmonically arranged comprising the steps of:
 using a blasting machine which ejects ejection powder with a compressed gas in a cabinet and causes the ejection powder to collide against an object to be collided and comprises dust collecting means for suctioning an inside of the cabinet and removing/collecting power dusts; and   performing blasting of causing a powdery metal material having an average grain diameter of 10 to 200 μm and a medium substance having hardness equal to or higher than that of the powdery metal material to collide with each other repeatedly at an ejection speed of 100 to 300 m/sec, and exfoliate surface oxides from the powdery metal material and also form the fine grain region having a crystal grain diameter smaller than a crystal grain diameter of a center part of the powdery metal material in the vicinity of a surface of the powdery metal material.   
     
     
         2 . The method for surface treatment of a powdery metal material according to  claim 1 , wherein
 the dust collecting means of the blasting machine comprises a cyclone for classifying the power dusts and the ejection powder.   
     
     
         3 . The method for surface treatment of a powdery metal material according to  claim 1 , wherein
 in the dust collecting means of the blasting machine, the collected power dusts are stored with inflammable powder.   
     
     
         4 . The method for surface treatment of a powdery metal material according to  claim 1 , wherein
 the blasting is performed by using the powdery metal material as the ejection powder and the medium substance as the object to be collided.   
     
     
         5 . The method for surface treatment of a powdery metal material according to  claim 1 , wherein
 the blasting is performed by using the medium substance with a powdery shape as the ejection powder and the powdery metal material as the object to be collided.   
     
     
         6 . The method for surface treatment of a powdery metal material according to  claim 1 , wherein
 the medium substance is made a powdery metal material of the same material and the same average grain diameter as the powdery metal material, and the ejection powder and the object to be collided are both made into the powdery metal material.   
     
     
         7 . The method for surface treatment of a powdery metal material according to  claim 1 , wherein
 a material of the medium substance is metal having hardness equal to or higher than hardness of the powdery metal material or ceramic having hardness equal to or higher than hardness of the powdery metal material after the surface treatment.   
     
     
         8 . The method for surface treatment of a powdery metal material according to  claim 2 , wherein
 in the dust collecting means of the blasting machine, the collected power dusts are stored with inflammable powder.   
     
     
         9 . The method for surface treatment of a powdery metal material according to  claim 2 , wherein
 the blasting is performed by using the powdery metal material as the ejection powder and the medium substance as the object to be collided.   
     
     
         10 . The method for surface treatment of a powdery metal material according to  claim 3 , wherein
 the blasting is performed by using the powdery metal material as the ejection powder and the medium substance as the object to be collided.   
     
     
         11 . The method for surface treatment of a powdery metal material according to  claim 4 , wherein
 the blasting is performed by using the powdery metal material as the ejection powder and the medium substance as the object to be collided.   
     
     
         12 . The method for surface treatment of a powdery metal material according to  claim 2 , wherein
 the blasting is performed by using the medium substance with a powdery shape as the ejection powder and the powdery metal material as the object to be collided.   
     
     
         13 . The method for surface treatment of a powdery metal material according to  claim 3 , wherein
 the blasting is performed by using the medium substance with a powdery shape as the ejection powder and the powdery metal material as the object to be collided.   
     
     
         14 . The method for surface treatment of a powdery metal material according to  claim 4 , wherein
 the blasting is performed by using the medium substance with a powdery shape as the ejection powder and the powdery metal material as the object to be collided.   
     
     
         15 . The method for surface treatment of a powdery metal material according to  claim 2 , wherein
 the medium substance is made a powdery metal material of the same material and the same average grain diameter as the powdery metal material, and the ejection powder and the object to be collided are both made into the powdery metal material.   
     
     
         16 . The method for surface treatment of a powdery metal material according to  claim 3 , wherein
 the medium substance is made a powdery metal material of the same material and the same average grain diameter as the powdery metal material, and the ejection powder and the object to be collided are both made into the powdery metal material.   
     
     
         17 . The method for surface treatment of a powdery metal material according to  claim 4 , wherein
 the medium substance is made a powdery metal material of the same material and the same average grain diameter as the powdery metal material, and the ejection powder and the object to be collided are both made into the powdery metal material.   
     
     
         18 . The method for surface treatment of a powdery metal material according to  claim 2 , wherein
 a material of the medium substance is metal having hardness equal to or higher than hardness of the powdery metal material or ceramic having hardness equal to or higher than hardness of the powdery metal material after the surface treatment.   
     
     
         19 . The method for surface treatment of a powdery metal material according to  claim 3 , wherein
 a material of the medium substance is metal having hardness equal to or higher than hardness of the powdery metal material or ceramic having hardness equal to or higher than hardness of the powdery metal material after the surface treatment.   
     
     
         20 . The method for surface treatment of a powdery metal material according to  claim 4 , wherein
 a material of the medium substance is metal having hardness equal to or higher than hardness of the powdery metal material or ceramic having hardness equal to or higher than hardness of the powdery metal material after the surface treatment.