Method of Preparing Metal Matrix Composite and Coating Layer and Bulk Prepared Thereby

Abstract

This invention provides a method of preparing a metal matrix composite, and a coating layer and bulk prepared by using the same and in particular, it provides a method of preparing a metal matrix composite, which comprises the steps of providing a substrate; preparing a mixed powder comprising i) a first metal powder comprising a metal, alloy or mixture particle thereof, ii) a second metal powder comprising an intermetallic compound forming metal particle which forms an intermetallic compound along with the metal or the alloy element of the alloy, and iii) a ceramic powder comprising a ceramic or mixture particle thereof; injecting the mixed powder prepared above into a spray nozzle for coating; coating the mixed powder on the surface of the substrate by accelerating the mixed powder in the state of non-fusion at a speed of 300 to 1,200 m/s by the flow of transportation gas flowing in the spray nozzle; and forming the intermetallic compound by the thermal treatment of the coated coating layer, and a coating layer and bulk prepared by using the same, whereby the coating layer and bulk material with high wear resistance and excellent resistance against fatigue crack on the surface without causing damages such as heat strain to the substrate during the preparation of the coating layer can be provided.

1 . A method of preparing a metal matrix composite, the method comprising the steps of:
 providing a substrate;   preparing a mixed powder comprising i) a first metal powder comprising a metal, alloy or mixture particle thereof, ii) a second metal powder comprising an intermetallic compound forming metal particle which forms an intermetallic compound along with the metal or the alloy element of the alloy, and iii) a ceramic powder comprising a ceramic or mixture particle thereof;   injecting the mixed powder prepared above into a spray nozzle for coating;   coating the mixed powder on the surface of the substrate by accelerating the mixed powder in the state of non-fusion at a speed of 300 to 1,200 m/s by the flow of transportation gas flowing in the spray nozzle; and   forming the intermetallic compound by the thermal treatment of the coated coating layer.   
   
   
       2 . The method of preparing the metal matrix composite of  claim 1  wherein the metal of the first metal powder is aluminum or alloy thereof, and the intermetallic compound forming metal particle of the second metal powder is a metal selected from the group consisting of titanium, nickel, chromium, iron and combination thereof. 
   
   
       3 . The method of preparing the metal matrix composite of  claim 1  wherein the ceramic of the ceramic powder is oxide, carbide, nitride or mixture thereof. 
   
   
       4 . The method of preparing the metal matrix composite of  claim 3  wherein the ceramic is alumina or SiC. 
   
   
       5 . The method of preparing the metal matrix composite of  claim 3  wherein the ceramic particle to be mixed into the mixed powder is supplied in the form of an agglomerated powder. 
   
   
       6 . The method of preparing the metal matrix composite of claim  1  wherein the substrate is aluminum, aluminum alloy, cast, ceramic or resin. 
   
   
       7 . The method of preparing the metal matrix composite of  claim 1  wherein the coating efficiency in the coating step is kept at most 50%. 
   
   
       8 . The method of preparing the metal matrix composite of  claim 1  wherein the metal of the first metal powder is aluminum or alloy thereof, the intermetallic compound forming metal particle of the second metal powder is a metal selected from the group consisting of titanium, nickel, chromium, iron and combination thereof, and the speed of the powder to be coated on the substrate is 300 to 500 m/s. 
   
   
       9 . The method of preparing the metal matrix composite of  claim 1  wherein the nozzle is a convergence-straight nozzle or convergence-divergence nozzle having a throat and the injection of the mixed powder is carried out at the divergence or straight section of the nozzle via an injection tube located through the throat. 
   
   
       10 . The method of preparing the metal matrix composite of  claim 9  wherein when the mixed powder is injected into the nozzle, the injection pressure is 90 to 120 psi. 
   
   
       11 . The method of preparing the metal matrix composite of  claim 1  wherein when the mixed powder is coated through the nozzle, the temperature of the transportation gas fed into the nozzle is 280±5° C. 
   
   
       12 . The method of preparing the metal matrix composite of  claim 1  wherein the mixing ratio of the ceramic powder or the mixing ratio of the second powder to the first metal powder has a concentration gradient as it goes to outer surface from the substrate surface. 
   
   
       13 . The method of preparing the metal matrix composite of  claim 1  wherein the particle size of the second metal powder or the particle size of the ceramic powder has a constant gradient with regard to particle size as it goes to outer surface from the substrate surface. 
   
   
       14 . The method of preparing the metal matrix composite of  claim 1  wherein the thermal treatment step is carried out at a temperature not higher than the eutectic temperatures of the first metal powder and the second metal powder. 
   
   
       15 . The method of preparing the metal matrix composite of  claim 14  wherein the metal of the first metal powder is aluminum or alloy thereof, the intermetallic compound forming metal particle of the second metal powder is a metal selected from the group consisting of titanium, nickel, chromium, iron and combination thereof, and the thermal treatment step is carried out at least 500° C. 
   
   
       16 . The method of preparing the metal matrix composite of  claim 1  further comprising the step of separating the part formed in the coating step from the substrate after the thermal treatment step. 
   
   
       17 . A metal matrix composite coating layer prepared by the method of preparing the metal matrix composite of  claim 1 . 
   
   
       18 . The metal matrix composite coating layer of  claim 17  wherein the thickness of the coating layer is 10 um to 1 mm. 
   
   
       19 . A metal matrix composite bulk prepared by the method of preparing the metal matrix composite of  claim 16 .