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.

Description

TECHNICAL FIELD[0001]This invention relates to a method of preparing a metal matrix composite, and a metal matrix composite coating layer and metal matrix composite bulk prepared by using the same. More particularly, the invention relates to a method of preparing a coating layer with wear resistance and excellent resistance against fatigue crack by securing high hardness by the dispersion of intermetallic compounds and ceramic particles without causing damages such as heat strain to a substrate in the process of preparing the coating layer and a method of providing a bulk which is prepared by separating the coating layer from the substrate, and a coating layer and bulk prepared thereby.BACKGROUND ART[0002]Dispersion reinforcement methods are used to improve the strength, hardness, wear resistance of alloys or metals. The dispersion reinforcement methods form a structure of intermetallic compounds being dispersed within the matrix of alloys or metals and their representative examples...

AI Technical Summary

Benefits of technology

[0029]In accordance with the method of preparing metal matrix composite of the invention and the metal matrix composite coating layer and bulk prepared by using the same, the production of metal matrix composites where intermetallic compounds and ceramic powders are dispersed is possible at low temperatures in comparison with the prior art so that there is no likelihood of causing damages by thermal strain and thermal shock to the substrates, the growth of intermetallic compounds was suppressed so that mechanical characteristics such as high temperature strength are improved, and the accumulation of heat on the coating layers is prevented and crack generation between the substrates and coating layers or inside the coating layers is suppressed so that res

Problems solved by technology

Accordingly, such dispersion reinforcements as precipitation hardening are inappropriate for heat resistant aluminum alloys.

However, thin aluminum oxide (Al2O3) is formed on the surface of the aluminum metal powder in air even at room temperatures and this surface aluminum oxide membrane interferes the reaction of aluminum and other metal elements and thus inhibits the formation of intermetallic compounds.

Accordingly, as the powder metallurgy requires thermal treatment at a high temperature above the melting point of the alloys to produce intermetallic compounds, it proposes high costs resulting from high temperature operation and safety securing problems of facilities.

Further, the powder metallurgy involves complex manufacturing process including the suitable control of sintering atmosphere in order to prevent the oxidation of aluminum at high temperature in the course of sintering and according to the powder metallurgy, the formation of intermetallic compounds with transition metals having high melting points such as Ti or Ni has been known to be very difficult.

Besides, in the powder metallurgy, as a desired shape is prepared by a mold, it costs a lot to prepare the mold and it also has size limitation.

This method generates the same problems as in the casting.

In particular, where aluminum-transition metal alloys are prepared by the thermal spraying, coarse secondary phases are formed within the aluminum matrix and they exhibit inferior alloy characteristics.

Hence, ac

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