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Method for manufacturing nanophase TiC-based composite powders by metallothermic reduction

Inactive Publication Date: 2006-06-08
KOREA INST OF MASCH & MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0010] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a method for manufacturing TiC powder, TiCN powder, or nanophase TiC and TiCN composite powders containing Ni, Co and Al as alloy elements by means of metallothermic reduct

Problems solved by technology

These processes have difficulty in their commercial uses due to the following problems.
That is, the reduction / carburization of titanium dioxide requires a very high reaction temperature of as high as 2000° C., which is economically disadvantageous.
Since the direct carburization using Ti and TiH2 and self heated sintering processes use an expensive starting material (high purity sponge titanium powder), there is a problem of high manufacturing costs.
The sol-gel process and the mechanical alloying (MA) process have problems of difficult stoichiometric manufacturing of TiC and TiCN powders and serious impurity incorporation during manufacture of TiC and TiCN powders, etc.
In addition, according to the above-mentioned processes, since finally manufactured powders are often obtained in the form of oxides such as TiCxOy or TiCxNyOz, there is a difficulty in the manufacture of desired high quality powders.
Furthermore, the processes require a separate grinding step, such as re-milling, to obtain a desired particle size, owing to severe sintering of TiC by high reaction temperature.

Method used

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  • Method for manufacturing nanophase TiC-based composite powders by metallothermic reduction
  • Method for manufacturing nanophase TiC-based composite powders by metallothermic reduction
  • Method for manufacturing nanophase TiC-based composite powders by metallothermic reduction

Examples

Experimental program
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Effect test

example 1

[0070] This Example describes a method for manufacturing TiC by means of metallothermic reduction. This Example was based on the following reaction 2.

TiCl4(g)+CCl4(g)+4Mg(l)→TiC(s)+4MgCl2(l)  (2)

[0071] The purities of TiCl4 and CCl4 were 99.9%. First, 1 mole (189.7 g) of TiCl4 was prepared. Since the boiling point of CCl4 is lower than that of TiCl4, that is, more volatile, CCl4 is first evaporated. Accordingly, some amount of CCl4 was condensed at the inner wall of a reactor and thus did not react with molten magnesium. This lowered the content of fixed carbon in final TiC compound.

[0072] To avoid this disadvantage, 1.05 moles (157.3 g) of CCl4 was set as a minimum amount and 1.15 moles (172.3 g) of CCl4 was set as a maximum amount, relative to the stoichiometric ratio (149.8 g) with TiCl4.

[0073] The purity of magnesium, a reducing agent of a starting solution of titanium tetrachloride in carbon tetrachloride, was 99.9%. Although 4 moles of magnesium corresponds to 97.3 g, a su...

example 2

[0089] This Example describes a method for manufacturing TiCN by means of metallothermic reduction. Specifically, a TiCN compound having a composition TiC0.5N0.5 was manufactured in the same manner as in Example 1 except that a solution of TiCl4 in C2Cl4 was used as a starting solution and nitrogen (N2) gas was used to create the atmosphere of a closed container instead of argon (Ar) gas.

[0090] The TiCN compound having a composition TiC0.5N0.5 was manufactured, based on the following reaction 4:

TiCl4(g)+1 / 4C2Cl4(g)+5 / 2Mg(l)+(1 / 4N2(g))→TiC0.5N0.5(s)+5 / 2MgCl2(l)  (4)

[0091] TiCl4, C2Cl4 and Mg were used in the amounts of 189.7 g, 87.0 g and 250 g, respectively. Changes in the contents of free carbon, fixed carbon and fixed nitrogen at various feeding rates of the starting solution into molten magnesium and various reaction temperatures are shown in FIG. 6.

[0092] When Ti, separated by the reduction of Mg, was bonded to ½C atom, bonding with a nitrogen atom followed, unlike in the ma...

example 3

[0100] This Example describes a method for manufacturing a TiC+Ni (Al, Co) composite or TiCN+Ni (Al, Co) composite by means of metallothermic reduction.

[0101] Specifically, the TiC+Ni composite was manufactured in the same manner as in Examples 1 and 2 (e.g., reaction temperature: above 1000° C. and feeding rate: below 20 g / min) except that molten magnesium alloy including at least one metal selected from nickel (Ni), aluminum (Al) and cobalt (Co) was used instead of pure magnesium. In this Example, molten Mg—Ni alloy was used as a reducing agent.

[0102] The TiC+Ni composite was manufactured, based on the following reaction 5:

TiCl4(g)+1 / 2C2Cl4(g)+3Mg / (Ni)(l)→TiC(s)+(Ni)(s)+3MgCl2(l)  (5)

[0103] Referring to the reaction 5, since Al or Co can be used instead of Ni, a TiC(s)+Al(s) composite or TiC(s)+Co(s) composite can be manufactured. In addition, in the case where nitrogen gas was used to create the atmosphere of the closed container, TiCN(s)+Al, Ni, Co(s) composites can be manuf...

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Abstract

Disclosed herein is a method for economically manufacturing high quality TiC powder, TiCN powder or ultrafine nanophase TiC+Ni (Co, Al) and TiCN+Ni (Co, Al) composite powders by means of metallothermic reduction. The method comprises the steps of preparing a starting solution of titanium tetrachloride (TiCl4) in a carbon chloride, feeding the starting solution into a closed container containing molten magnesium (Mg) under inert atmosphere, vacuum-separating unreacted liquid-phase Mg and magnesium chloride (MgCl2) remaining after reduction of magnesium from the closed container, and collecting a TiC compound from the closed container. TiC powder, TiCN powder or ultrafine nanophase TiC+Ni (Co, Al) and TiCN+Ni (Co, Al) composite powders having a particle size of a few tens nm can be manufactured in a simpler manner using economically advantageous starting materials such as titanium tetrachloride and carbon chlorides.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. application Ser. No. 10 / 600,159 filed Jun. 20, 2003. The entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a method for manufacturing nanophase TiC-based composite powders by means of metallothermic reduction, and more particularly to a method for economically manufacturing high quality TiC powder, TiCN powder or ultrafine nanophase TiC+Ni (Co, Al) and TiCN+Ni (Co, Al) composite powders by means of metallothermic reduction. [0004] 2. Description of the Related Art [0005] In general, titanium carbide (TiC) and titanium carbo-nitride (TiCN) powders are currently used as additives for improving high-temperature hardness and wear-resistance of WC / Co hard metal tools. In addition, these powders are widely used as starting powders for manufacturing cermet tools, rolls and molds by forming co...

Claims

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Application Information

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IPC IPC(8): C01B31/34B22F9/18B82B3/00C01B21/082C01B31/30C01B32/949C01F5/30C01G23/00C22B5/04C22B34/12C22C1/05
CPCB82Y30/00C01B21/0828C01B31/305C01F5/30C01P2002/60C01P2002/72C01P2002/77C01P2004/03C01P2004/62C01P2004/64C01P2004/80C01P2006/80C04B35/5611C04B35/58021C04B35/6264C04B2235/3275C04B2235/3279C04B2235/3843C04B2235/3856C04B2235/3886C04B2235/402C04B2235/404C04B2235/405C04B2235/5454C04B2235/72C04B2235/721C04B2235/724C04B2235/725C04B2235/80C22B5/04C22B34/1272C22B34/1295C22C1/053C01B32/921C01G23/00B82B3/00
Inventor LEE, DONG-WONKIM, BYOUNG-KEE
Owner KOREA INST OF MASCH & MATERIALS
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