Preparation method for magnesium matrix composite

Abstract

The invention relates to a preparation method for a magnesium matrix composite. The preparation method comprises the following steps: (1) preparing magnesium ingots as raw materials and salt flux and reinforcements; (2) placing the salt flux in a crucible, performing heating to prepare salt flux melts, adding the reinforcements; (3) performing pouring into a normal-temperature crucible, and performing cooling to obtain precursors; (4) adding the raw materials in an iron crucible, and performing melting at 953K-1043K; (5) placing the precursors in raw material melt, after stirring, under a condition of 953K-993K, performing standing so that scum and melt are obtained; and (6) removing the scum, lowering temperature to 973K-982K, and performing casting. The method provided by the present invention is simple in process and low in cost. The method can be used for preparing bulk structural members of the magnesium matrix composite, and can be used for automatic production.

What is claimed is: 
     
         1 . A preparation method for a magnesium matrix composite, comprising:
 (1) preparing magnesium ingots as raw materials; preparing salt flux and reinforcements, wherein the salt flux is a mixture of barium chloride, magnesium chloride, sodium chloride and calcium chloride, the barium chloride accounts for 35-50% of a total mass of the salt flux, the magnesium chloride accounts for 10-20% of a total mass of the salt flux, the sodium chloride accounts for 10-20% of a total mass of the salt flux, a balance is the calcium chloride and impurities, the impurities account for no more than 1% of the total mass of the salt flux, the reinforcements are elementary metal, rare earth oxides, carbides, borides or metal oxides, the elementary metal is W, Mo or Ni, the rare earth oxides are La 2 O 3 , CeO 2  or Y 2 O 3 , the carbides are TiC or SiC, the borides are ZrB 2 , the metal oxides are MgO or SiO 2 , the reinforcements are 0.1%-30% of a total volume of the raw materials, and the reinforcements are 1%-50% of a total volume of the salt flux;   (2) placing the salt flux in a clay crucible or a graphite crucible, performing heating to 773K-923K to prepare salt flux melts, placing the reinforcements in the salt flux melts, and performing stirring until the reinforcements are uniformly dispersed to prepare a liquid-solid mixture;   (3) pouring the liquid-solid mixture into a normal-temperature clay crucible or graphite crucible, and performing cooling to normal temperature to obtain precursors;   (4) preheating an iron crucible until a body of the iron crucible is in a dark red heat, then placing the raw materials in the iron crucible, and performing melting on the raw materials at 953K-1043K to form a raw material melt;   (5) placing the precursors in the raw material melt of 953K-1043K, performing stirring until the precursors are dispersed uniformly, under a condition of 953-993K, adding refining agents, performing stirring for refining, after the refining is finished, controlling temperature to 1013K-1023K, and performing standing so that impurity components are separated from composite components, and scum and a composite melt are obtained;   (6) removing the scum from a surface of the composite melt, then cooling the composite melt to 973-982K, and performing casting to form the magnesium matrix composite.   
     
     
         2 . The preparation method according to  claim 1 , wherein a purity of the magnesium ingots is greater than or equal to 99.85%. 
     
     
         3 . The preparation method according to  claim 1 , wherein the reinforcements are fibers, particles or whiskers, wherein a particle size of the particles is 300 nm-20 μm, a diameter of the whiskers is 0.1 μm-1 μm, a length is 10 μm-100 μm, a diameter of the fibers is 5 μm-20 μm, and a continuous length is 10 mm-70 mm. 
     
     
         4 . The preparation method according to  claim 1 , wherein in the step (2), a stirring rate is 100 r/min-200 r/min, and a time is 2 min-10 min. 
     
     
         5 . The preparation method according to  claim 1 , wherein in the step (5), a stirring rate is 100 r/min-300 r/min, and a time is 5 min-15 min. 
     
     
         6 . The preparation method according to  claim 1 , wherein in the step (5), a standing time is 10 min-30 min. 
     
     
         7 . The preparation method according to  claim 1 , further comprising in the step (1): preparing the magnesium ingots and other metal components as the raw materials; when the step (4) is performed, placing the magnesium ingots and the other metal components in the iron crucible jointly, performing melting, and preforming stirring and uniform mixing to form a raw material melt, wherein the other metal components are one or more of aluminum ingots, zinc ingots, manganese chloride, magnesium-rare earth alloys, magnesium-zirconium alloys and magnesium-silicon alloys, and aluminum, zinc, manganese, rare earth, zirconium and silicon in the other metal components account for no more than 10% of a total mass of the raw materials. 
     
     
         8 . The preparation method according to  claim 1 , further comprising in the step (4): enabling covering flux to be scattered onto a surface of the raw material melt so as to prevent magnesium from burning, wherein the covering flux is No. 2 flux; when the step (5) is performed, mixing the covering flux with the scum; and when the step (6) is performed, removing the covering flux and the scum together. 
     
     
         9 . The preparation method according to  claim 1 , wherein in the step (5), the refining agents are the No. 2 flux. 
     
     
         10 . The preparation method according to  claim 1 , wherein raw material components in the magnesium matrix composite account for 80-99.9% of a total volume, and components of the reinforcements account for 0.1-20% of the total volume.