WO2014032418A1

WO2014032418A1 - Cermet and method for preparing cermet

Info

Publication number: WO2014032418A1
Application number: PCT/CN2013/072020
Authority: WO
Inventors: 颜焰; 陈辉; 万武辉
Original assignee: 成都美奢锐新材料有限公司
Priority date: 2012-08-29
Filing date: 2013-02-28
Publication date: 2014-03-06
Also published as: CN102839311B; CN102839311A

Abstract

A Ti(C,N)-based cermet with excellent comprehensive mechanical property, a cutting tool using the cermet and a method for preparing a reinforced and toughened Ti(C,N)-based cermet. The cermet comprises a hard phase, a bounding phase, and a strengthening phase. The hard phase comprises one or more compounds that are selected from a group consisting of carbides, nitrides, carbonitrides and carbonitride solid solutions of Group IV, Group V and Group VI metals in the periodic table, and Ti is a main metallic element that forms the compounds. The bounding phase mainly comprises metals of the iron group. The strengthening phase comprises AlN nanowires and TiAlN compounds formed on junctions between the AlN nanowires and the hard phase compounds. The proportion of the total weight of the Al element in the AlN nanowires and TiAlN compounds based on the weight of the cermet is greater than 0% and equal to or less than 5%. The hardness, bending strength and fracture toughness of the cermet are improved.

Description

Method for preparing cermet and cermet

The present invention relates generally to cermets and methods for their preparation, and more particularly to Ti(C,N)-based cermets and methods for their preparation.

Background technique

Ti ( C, N)-based cermets are mainly composed of Ti ( C, N) powder or a mixed powder of TiC and TiN as a hard phase, and a metal such as Co, Ni or Mo as a binder phase, and usually A transition metal metal carbide such as WC, TaC, NbC, Mo ₂ C, VC, Cr ₃ C ₂ or the like is added as a composite material obtained by pulverizing, mixing, molding, and sintering, and is mainly used for manufacturing a cutting tool. Among them, the selection range of the bonding phase metal is wide, and the patent document of CN102046823A (Applicant: Sumitomo Electric Industries Co., Ltd.) suggests that it can be arbitrarily selected among the iron group metals. In fact, in combination with this patent document, the hard phase in the Ti (C, N)-based cermet can be summarized as: It is a carbide selected from metals of Groups 4, 5 and 6 of the Periodic Table of the Elements. And one or more compounds of a nitride, a carbonitride, and a carbonitride solid solution, and the metal element constituting these compounds is mainly Ti. At present, in order to improve the hardness, fracture toughness and flexural strength of Ti (C, N)-based cermets, the research direction in the field mainly focuses on the addition of transition metal carbides.

Reference 1 "Impact of the addition of A1N to the mechanical properties and microstructure of Ti (C, N)-based cermets, Liu Ning et al., Physical and Chemical Testing, Physical Physics, 1997", in Ti (C, N)-based metals When the A1N micron powder is added to the ceramic, a Y ' [Ni ₃ (Al, Ti )] phase is formed in the bonding phase, and the γ ' phase increases the hindrance of dislocation motion, thereby strengthening the bonding phase, thereby improving The strength and hardness of cermets. Reference 2 - "Nano-TiN modified Ti (C, N)-based cermets for thermal shock resistance, Zhang Xiaobo et al., Carbide, Vol. 24, No. 3, September 2007" pointed out that in Ti (C, N) The addition of nano-TiN to the base cermet can significantly improve the comprehensive mechanical properties of the cermet. The main reason is that the dissolution of the nano-TiN in the binder phase reduces the solubility of the hard phase in the binder phase. The grain of the hard phase is refined; 2. The nano TiN particles are pinned to the dislocation, which increases the hindrance of dislocation motion; 3. The nano TiN is easily dissolved in the bonding phase, and the Ti is bonded to the phase. The metal acts as a solid solution strengthening.

Summary of the invention

The present invention aims to provide a Ti (C, N)-based cermet having excellent comprehensive mechanical properties, and a cutting tool using the cermet and a preparation method of the Ti (C, N)-based cermet capable of enhancing toughening .

To this end, the cermet of the present invention comprises:

a hard phase, the hard phase being composed of one or more compounds selected from the group consisting of carbides, nitrides, carbonitrides, and carbonitride solid solutions of Group 4, Group 5, and Group 6 metals of the Periodic Table; And the metal elements that make up these compounds are mainly Is Ti _;

a bonding phase, the bonding phase is mainly composed of an iron group metal;

a strengthening phase, the strengthening phase comprising an A1N nanowire and a TiAIN compound formed on a bonding surface of the A1N nanowire and the hard phase compound; the total weight of the A1 element in the A1N nanowire and the TiAIN compound is per unit metal The ratio of ceramic weight is >0% and 5%.

It was found that the TiAIN compound formed on the bonding surface of the A1N nanowire and the hard phase compound during sintering is a high temperature stable compound which effectively isolates the diffusion of Ti, N and C atoms in the hard phase. The effect is to effectively inhibit the dissolution and precipitation of Ti, N, C atoms in the bonding phase, reduce the solubility of titanium carbonitride in the bonding phase, and reduce the dissolution and growth of titanium carbonitride in the bonding phase. The resulting N decomposition enhances the stability of the titanium carbonitride, refines the titanium carbonitride grains, and improves the hardness and toughness of the cermet. At the same time, the A1N nanowires have a fiber-reinforced effect on the cermet, which further enhances the strength and toughness of the cermet. Based on such a mechanism, the Ti (C, N)-based cermet of the present invention is improved in hardness, flexural strength and fracture toughness, and achieves excellent comprehensive mechanical properties. However, the test also shows that if the total weight of the A1 element in the A1N nanowires and the TiAIN compound accounts for more than 5% by weight per unit of cermet, an increase in the brittle phase in the material will result in a decrease in the flexural strength and fracture toughness of the material to Unacceptable level.

In the Ti (C, N)-based cermet of the present invention, the total weight of the A1 element in the A1N nanowire and the TiAIN compound is preferably from 2% to 4% by weight per unit of the cermet. Tests have shown that Ti (C, N)-based cermets are significantly superior to existing metals in terms of hardness, flexural strength and fracture toughness when the total weight of the A1 element in the A1N nanowires and the TiAIN compound is within the above range. Ceramics; If the A1 content is less than 2%, the effect of strengthening and toughening is not very obvious. If the A1 content is higher than 4%, the increase of the brittle phase will lead to a decrease in the flexural strength and fracture toughness of the material.

The cutting tool of the present invention has a cermet substrate, and the cermet substrate comprises:

a hard phase, the hard phase being composed of one or more compounds selected from the group consisting of carbides, nitrides, carbonitrides, and carbonitride solid solutions of Group 4, Group 5, and Group 6 metals of the Periodic Table; And the metal element constituting these compounds is mainly Ti;

a bonding phase, the bonding phase is mainly composed of an iron group metal;

a strengthening phase comprising an A1N nanowire and a TiAIN compound formed on a bonding surface of the A1N nanowire and the hard phase compound, wherein the total weight of the A1 element in the A1N nanowire and the TiAIN compound is per unit metal The proportion of ceramic weight is less than 5%.

For the reasons stated above, in the cutting tool of the present invention, the total weight of the A1 element in the A1N nanowires and the TiAIN compound is preferably from 2% to 4% by weight per unit of the cermet matrix. A method for preparing a cermet, comprising the steps of:

1) Preparation of powder mixture

Raw material composition and ratio (% by weight)

Ti (C, N) powder: 40%~60%

Iron group metal: 10%~20%

A1N nanowire: 3%~6%

Transition metal carbide: the rest

According to the above components and ratios, the Ti (C, N) powder, the iron group metal and the transition metal carbide are pulverized and mixed, and then the A1N nanowires are added and mixed to prepare a powder mixture;

2) Forming

Forming the above powder mixture into a compact by pressure forming;

3) Sintering

The green compact is sintered in a vacuum or a protective atmosphere, and is kept at 1380 ° C to 1480 ° C for 1 hour to 3 hours during sintering, and the cermet is obtained after cooling.

It was examined that the TiAIN compound to be formed on the bonding surface of the A1N nanowire and the hard phase compound by the above preparation method. Further, in the prepared Ti (C, N)-based cermet, the total weight of the A1 element in the A1N nanowire and the TiAIN compound accounts for 2% to 4% by weight per unit of the cermet.

Specifically, the iron group metal is selected from one or more of Co, Ni, Fe, and Cu.

Specifically, the transition metal carbide is selected from one or more of WC, TaC, NbC, and Mo ₂ C.

Further, the transition metal carbide is composed of WC, TaC, NbC and Mo ₂ C, wherein the sum of the weights of WC, TaC and NbC is 10% to 20% of the powder mixture, and the balance is WC.

Pressure forming can be selected by methods such as molding, isostatic pressing, extrusion and rolling.

Compared with Reference 1, the position, morphology and structure of the strengthening phase formed in the Ti (C, N)-based cermet of the present invention are different, and the strengthening mechanism for the Ti (C, N)-based cermet is also Different. In addition, it can also be seen from the specific implementations to be given in the following description that the Ti (C, N)-based cermet of the present invention is significantly higher in hardness and flexural strength than Ti (C, N in Reference Document 1). The hardness and bending strength of the base cermet.

Compared with the reference 2, the Ti (C, N)-based cermet of the present invention is isolated from the Ti, N, and C atoms in the hard phase by the TiAIN compound formed on the bonding surface of the A1N nanowire and the hard phase compound. The diffusion is to achieve the purpose of refining the hard phase grains, while the reference 2 is to refine the hard phase grains by the dissolution of the nano TiN in the bonding phase, so the two also exist in nature. difference. DRAWINGS

Fig. 1 is a graph showing the change of the hardness of the material of the test example 1-8 of the present application to the amount of the A1 nanowire added.

Fig. 2 is a graph showing changes in the flexural strength of the material of Test Example 1-8 of the present application versus the amount of A1 nanowire added.

Fig. 3 is a graph showing changes in the flexural strength of the material of Test Example 1-8 of the present application versus the amount of A1 nanowire added.

The vertical axis unit of Fig. 1 is HRA, the vertical axis unit of Fig. 2 is Mpa, and the vertical axis unit of Fig. 3 is Mpam ^1/2 .

In Figures 1, 2 and 3, the horizontal axis is in weight percent.

detailed description

Ti (C, N)-based cermets were fabricated, and the hardness, fracture toughness and flexural strength of these Ti (C, N)-based cermets were examined.

The basic steps of the test are:

1) Preparation of powder mixture

The raw materials are weighed according to the set components and ratios, and mixed ball milling is carried out in a drum ball mill at a ball-to-ball ratio (6 to 8): 1, 20 to 40 rpm, for 60 to 90 hours. Powder mixture.

The addition of the A1N nanowires was completed at the start of the last 10 hours of ball milling.

2) Forming

A molding agent such as paraffin or PEG is added to the powder mixture, and the mixture is uniformly stirred. After sieving, it is molded into a compact in a mold, and the molding pressure is 100 MPa to 300 MPa.

3) Sintering

The green compact is sintered in a vacuum or a protective atmosphere, and is kept at 1380 ° C to 1480 ° C for 1 hour to 3 hours during sintering, and is cooled to obtain a Ti (C, N)-based cermet.

[Table 1]

The composition and ratio (% by weight) of the raw materials. Table 1

Test No. Ti (C, N) WC NbC Mo ₂ C Co Ni A1N Nanowire Powder

1 53 12 8 7 10 10 0

2 55 13 8 7 8 8 1

3 55 12 8 7 8 8 2

4 50 12 8 7 10 10 3

5 60 10 10 6 5 5 4

6 40 20 8 7 10 10 5

7 55 12 8 7 6 6 6

8 55 12 8 7 6 5 7 Description:

1. Test No. 1-8 corresponds to test number 1-8 in the following tables.

2. In the test of No. 1-8, the addition amount of A1N nanowires increased by 1% from 0%, and finally reached 7%.

3. For comparison, the transition metal carbides in the tests of No. 1-8 were selected from WC, NbC and Mo ₂ C. Those skilled in the art can determine the apparent _{addition, TaC, VC, Cr 3 C} 2 carbides and other transition metals can be used as such an additive.

4. For comparison, in the test of No. 1-8, the binder phase raw materials are all selected from Co and Ni o. However, it is obvious to those skilled in the art that in addition to Co and Ni, iron group metals such as Fe and Cu can be used as the binder. Phase metal.

5. The content of each component in the test of No. 1-8 is selected within the interval defined by the present invention.

6. Ti (C, N) powder, WC powder, NbC powder, Mo ₂ C powder, Co powder, Ni powder and A1N nanowires in the above table are all from commercially available products.

[Table 2]

Roller ball mill operating parameters Table 2

Speed ball milling time

Test number Ball material ratio A1N nanowire joining timing

(rev / min) (hours)

1 8:1 30 60 ―

2 7:1 30 70 Starting at the 60th hour of ball milling

3 7:1 30 70 Starting at the 60th hour of ball milling

4 8:1 30 60 Starting at the 50th hour of ball milling

5 7:1 30 70 Starting at the 60th hour of ball milling

6 8:1 30 80 Starting at the 70th hour of ball milling

7 7:1 30 70 Starting at the 60th hour of ball milling

8 7:1 30 70 Starting at the 60th hour of ball milling

[table 3]

Sintering condition

table 3

Test No. Environmental Gas Pressure Sintering Temperature Holding Time

(Mpa) (°C) (hours)

1 gas 6 1420 2

2 Vacuum ― 1440 3

3 vacuum ― 1440 2

4 gas 6 1420 2

5 gas 8 1440 1

6 gas 6 1450 3

7 Nitrogen 6 1440 1

8 nitrogen 5 1440 2

[Table 4]

test results Table 4

Test No. Material Hardness Material Flexural Strength Material Fracture Toughness

(HRA) (MPa) (Mpam ¹⁷² )

1 91. 5 1900 10. 3

2 91. 7 2100 10. 6

3 92. 1 2300 11. 4

4 92. 6 2500 12. 6

5 93. 5 2600 12. 1

6 92. 8 2700 14. 8

7 93. 5 2500 13. 3

8 93. 8 1800 10. 9

Further, it was found by X-ray photoelectron spectroscopy (XPS) that, in the samples of Test Nos. 1 to 3 and 5-8, a TiAIN compound was formed on the bonding surface of the A1N nanowire and the hard phase compound.

Test description:

1. Calculated, the ratio of the total weight of the A1N nanowires in the cermet obtained in the test No. 4 and the A1 element in the TiAIN compound to the weight of the cermet per unit is about 2%; the A1N nanowire in the cermet obtained in the test No. 7 And the total weight of the A1 element in the TiAIN compound is about 4% by weight per unit of the cermet, and the total weight of the A1N nanowire in the cermet of No. 8 and the A1 element in the TiAIN compound is the weight per unit of the cermet. The ratio is approximately 4.6 %.

2. In Fig. 1, the hardness of the cermet obtained by the test of No. 6 suddenly drops, which is related to the decrease of the addition amount of Ti (C, N) powder; in Fig. 3, the fracture toughness of the cermet obtained by the test of No. 5 suddenly drops, which It is related to the decrease in the amount of the binder phase metal added. Excluding the influence of these factors, the hardness, flexural strength and fracture toughness of the materials increased during the process of increasing the amount of A1N nanowires from 0% to 5%. The preferred A1N nanowires of the present invention are added in an amount of 3% to 6%. During this interval, the hardness, flexural strength and fracture toughness of the material are significantly better than those of the prior cermets.

Claims

Claim

1, cermet, including:

a hard phase, the hard phase being one or more compounds selected from the group consisting of carbides, nitrides, carbonitrides, and carbonitride solid solutions of Group 4, Group 5, and Group 6 metals of the Periodic Table of the Elements Composition, and the metal element constituting these compounds is mainly Ti _;

a bonding phase, the bonding phase is mainly composed of an iron group metal;

a strengthening phase comprising an A1N nanowire and a TiAlN compound formed on a bonding surface of the A1N nanowire and the hard phase compound, wherein the total weight of the A1 element in the A1N nanowire and the TiAlN compound is per unit metal The ratio of ceramic weight is >0% and 5%.

The cermet according to claim 1, wherein the total weight of the A1 element in the A1N nanowire and the TiAlN compound accounts for 2% to 4% by weight per unit of the cermet.

The cermet according to claim 1 or 2, wherein the iron group metal is one or more selected from the group consisting of Co, Ni, Fe, and Cu.

4. A cutting tool having a cermet substrate, the cermet substrate comprising:

a bonding phase, the bonding phase is mainly composed of an iron group metal;

a strengthening phase comprising an A1N nanowire and a TiAlN compound formed on a bonding surface of the A1N nanowire and the hard phase compound, wherein the total weight of the A1 element in the A1N nanowire and the TiAlN compound is per unit metal The proportion of ceramic weight is below 5%.

The cutting tool according to claim 4, wherein the total weight of the A1 element in the A1N nanowire and the TiAlN compound is 2% to 4% by weight per unit of the cermet matrix.

The cutting tool according to claim 4 or 5, wherein the iron group metal is one or more selected from the group consisting of Co, Ni, Fe, and Cu.

7. The preparation method of the cermet, comprising the following steps:

1) Preparation of powder mixture

Raw material composition and ratio (% by weight)

Ti (C, N) powder: 40%~60% Iron group metal: 10%~20%

A1N nanowire: 3 %~6 %

Transition metal carbide: the rest

2) Forming

Forming the above powder mixture into a compact by pressure forming;

3) Sintering

The method for producing a cermet according to claim 7, wherein the iron group metal is one or more selected from the group consisting of Co, Ni, Fe, and Cu.

The method for producing a cermet according to claim 7 or 8, wherein the transition metal carbide is one or more selected from the group consisting of WC, TaC, NbC, and Mo ₂ C.

10. The method of preparing a cermet according to claim 9, wherein: said transition metal carbide is composed of WC, TaC, NbC and Mo ₂ C, wherein the sum of WC, TaC and NbC weights The powder mixture is 10% to 20%, and the balance is WC.