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Solid-solution powder, method to prepare the solid-solution powder, cermet powder including the solid-solution powder, method to prepare the cermet powder, cermet using the cermet powder and method to prepare the cermet

a technology of solid-solution powder and cermet powder, which is applied in the direction of solid-state diffusion coating, titanium carbide, metallic material coating process, etc., can solve the problems of reducing the toughness of cermet, poor mechanical properties, and inability to achieve tangible effects, and achieves low toughness and high hardness

Active Publication Date: 2006-09-28
SEOUL NAT UNIV R&DB FOUND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides a solid-solution powder, a method for preparing the powder, a cermet powder, an agglomerate of the powder, and a cermet. The solid-solution powder has nano-sized crystallites and a complete solid-solution phase, which solves the problem of low toughness in conventional cermets. The cermet powder has increased hardness and toughness, making it suitable for use in cutting tools. The cermet powder can be agglomerated with a carbide or carbo-nitrite of at least two elements of metals selected from IVa, Va, and VIa Group metals of periodic table, or with at least one element of metals selected from Ni, Co, and Fe. The cermet powder can also be coated with a hard phase of TiC or other materials. The invention provides a solution for improving the mechanical properties of materials using cermets."

Problems solved by technology

However, in the TiC—Ni cermet system, coarsening of TiC grains results in poor mechanical properties.
Further, in case of preparing a cermet using TiC, upon sintered, binding phase metal of Ni is used as a liquid metal, so that a wetting angle comes to be large in comparison with that of a combination of WC—Co And rapid grain growth of TiC comes to occur, which cause the problem of reducing a toughness of the cermet.
In the 1960's and 1970's, to improve the toughness that was a great weakness of the TiC—Ni cermet system, there had been an attempt to add various kinds of elements thereto, which, however, could not have attained tangible results.
However, the cermet having such core / rim structure still has a problem in that the cermet has toughness lower than that of WC—Co hard alloy, so that the cermet cannot yet replace WC—Co completely.
Further, the strain developed at the interface between core and rim phases exerts a negative effect on the properties, facilitating crack propagation through the interface during machining.
Thus, there have been enormous efforts to produce homogeneous solid-solutions of single phase without core / rim structure in order to secure the application area of the cermet as broad as WC—Co However, many industrial attempts targeting this homogeneity have failed to provide it.

Method used

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  • Solid-solution powder, method to prepare the solid-solution powder, cermet powder including the solid-solution powder, method to prepare the cermet powder, cermet using the cermet powder and method to prepare the cermet
  • Solid-solution powder, method to prepare the solid-solution powder, cermet powder including the solid-solution powder, method to prepare the cermet powder, cermet using the cermet powder and method to prepare the cermet
  • Solid-solution powder, method to prepare the solid-solution powder, cermet powder including the solid-solution powder, method to prepare the cermet powder, cermet using the cermet powder and method to prepare the cermet

Examples

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Effect test

example 1

[0095] As an example, the anatase-TiO2 of purity 99+%, NiO of purity 99% (avg. particle size of 45 μm) and WO3 of purity 99+% (avg. particle size of 20 μm) were used.

[0096] They were mixed with carbon powder for the five target compositions as follows: (i) (Ti,W)C—Ni (containing 15 wt % of WC), (ii) (Ti,W)C—Ni (containing 30 wt % of WC), (iii) (Ti,W)(C,N)—Ni (containing 15 wt % of WC and C / N=2:1), (iv) (Ti,W)(C,N)—Ni (containing 30 wt % of WC and C / N=3:1), and (v) (Ti,W)C (containing 15 wt % of WC).

[0097] They were ground, i.e. high-energy ball milled using a planetary mill (Fritsch Pulverisette 7). Tungsten carbide (WC) balls with 5 mm in a diameter were used as milling media and mixed with powders at a ball-to-powder weight ratio of 20:1.

[0098] A tungsten carbide bowl was used and all milling was conducted at a speed of 250 RPM in air for 20 hours.

[0099] To this end, the ground nano powders were annealed at 1300° C. for one and half hours under a vacuum or hydrogen atmosphere ...

example 2

[0116] As an example, a simple target composition has been firstly selected, and to this end, TiO2, WO3, NiO nano oxides having a 50 nm crystallite size according to the respective contents has been prepared.

[0117] As a target composition, two compositions were selected as follows: (i) (Ti,W)C—Ni (containing 15 wt % of WC) and (ii) (Ti,W)C—Ni (containing 30 wt % of WC).

[0118] Carbon powders and above nano oxides prepared were mixed and ground, and the ground nano powders were annealed at 1300° C. for two hours under a vacuum or hydrogen, CH4, CO / CO2 atmosphere to be reduced, and carburized.

[0119] During sintering of the cermet powders prepared, 1˜100 torr of nitrogen is introduced to the furnace at the sintering temperature, and the pressure (1˜100 torr) is made to be kept to a cooling process.

[0120]FIG. 4a are photographs of FE-SEM showing the sintered specimen (1510° C. and one hour) of (Ti,W)C—Ni cermet powder (containing 15 wt % of WC) in nitrogen atmosphere prepared by the ...

example 3

[0127] As an example, a simple target composition has been firstly selected, and to this end, TiO2, WO3, NiO nano oxides having a 50 nm crystallite size according to the respective contents has been prepared.

[0128] As a target composition, four compositions were selected as follows: (i) (Ti,W)C—Ni (containing 15 wt % of WC), (ii) (Ti,W)C—Ni (containing 30 wt % of WC), (iii) (Ti,W)CN—Ni (containing 15 wt % of WC) and (iv) (Ti,W)CN—Ni (containing 30 wt % of WC).

[0129] Carbon powders and above nano oxides prepared were mixed and ground, and the ground nano powders were annealed at 1300° C. for two hours under a vacuum or hydrogen, CH4, CO / CO2 atmosphere to be reduced, and carburized. In case of carbo-nitrite, nitrogen was injected into a vacuum furnace.

[0130] During sintering of the cermet powders prepared, vacuum atmosphere (or argon, nitrogen) is used. Further, coating layer of TiN is formed on the surface of the cermet sintered by using PVD method. The coating layer of TiN show c...

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Abstract

Disclosed are a solid-solution powder, a method for preparing the solid-solution powder, a cermet powder including the solid-solution powder, a method for preparing the cermet powder, a cermet using the cermet powder and a method to prepare the cermet. According to the present invention, the problem of low toughness due to high hardness that conventional cermets (especially TiC or Ti(CN) based cermet) have is resolved because a complete solid-solution phase without core / rim structure is provided to the cermets as a microstructure thereof, and in which further increased the hardness as well as the toughness, thereby substantially and considerably increasing general mechanical properties of materials using the cermet, and thus substituting WC—Co Hard material and allowing manufacturing of cutting tools with high hardness and toughness.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a solid-solution powder, a method for preparing the solid-solution powder, a cermet powder including the solid-solution powder, a method for preparing the cermet powder, a cermet using the cermet powder and a method to prepare the cermet, which are adapted to materials for high-speed cutting tools and die used in a machine industry such as manufacture of machine, an automotive industry and so on, in order to improve general mechanical properties, particularly toughness and hardness for the materials. [0003] 2. Description of the Related Art [0004] For major cutting tools or wear-resistance tools utilized in metal cutting required for a machine industry, WC based hard alloys, various TiC or Ti(CN) based cermet alloys and other ceramic or high-speed steels, etc. Are used. [0005] A cermet means ceramic metal composite sinter. Usually, the cermet includes hard phase of TiC and Ti(CN) and...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C29/02B22F9/20C22C1/05C23C8/02C23C8/20C23C8/24C23C8/30C23C8/80C23C30/00
CPCB22F2999/00B82Y30/00C01B31/305C01B31/34C04B35/5611C04B35/58021C04B35/6265C04B35/62675C04B35/6268C04B2235/3231C04B2235/3232C04B2235/3839C04B2235/3843C04B2235/3847C04B2235/3856C04B2235/3886C04B2235/422C04B2235/5454C04B2235/549C22C1/055C22C29/02C23C8/02C23C8/20C23C8/24C23C8/30C23C8/80C23C30/005B22F9/04C01B32/921C01B32/949B22F9/20
Inventor KANG, SHINHOO
Owner SEOUL NAT UNIV R&DB FOUND