CN102839311A - Metal ceramic and preparation method thereof - Google Patents

Abstract

The invention discloses a Ti(C, N)-based cermet with excellent comprehensive mechanical properties, a cutting tool using the cermet, and a preparation method of the Ti(C, N)-based cermet capable of strengthening and toughening. The cermet of the present invention comprises: a hard phase, the hard phase is selected from carbides, nitrides, carbonitrides and carbonitride solid solutions of Group 4, Group 5 and Group 6 metals of the periodic table One or more compounds, and the metal elements constituting these compounds are mainly Ti; a bonding phase, the bonding phase is mainly composed of iron group metals; and a strengthening phase, the strengthening phase includes AlN nanowires and formed on The TiAlN compound on the bonding surface of the AlN nanowire and the hard phase compound; the ratio of the total weight of the Al element in the AlN nanowire and the TiAlN compound to the weight of the cermet is > 0% and ≤ 5%. The cermet is improved in hardness, bending strength and fracture toughness, and achieves excellent comprehensive mechanical properties.

Description

Cermet and method for preparing cermet

technical field

The invention mainly relates to cermets and a preparation method thereof, in particular to Ti(C, N)-based cermets and a preparation method thereof.

Background technique

Ti(C,N)-based cermet is a kind of hard phase with Ti(C,N) powder or mixed powder of TiC and TiN as the main raw material, Co, Ni, Mo and other metals as the binder phase raw material, and usually WC, TaC, NbC, Mo ₂ C, VC, Cr ₃ C ₂ and other transition metal carbides are also added as additives, which are composite materials formed by crushing, mixing-molding-sintering, and are mainly used to manufacture cutting tools. Among them, the selection range of the binder phase metal is relatively wide, such as CN102046823A (applicant: Sumitomo Electric Industries, Ltd.) patent document, it is proposed that the iron group metal can be selected arbitrarily. In fact, further combining with this patent document, the hard phase in Ti(C,N)-based cermet can be summarized as: it is composed of carbides of metals selected from Group 4, Group 5 and Group 6 of the periodic table , nitrides, carbonitrides, and carbonitride solid solutions are composed of one or more compounds, and the metal elements constituting these compounds are 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 this field mainly focuses on the addition of transition metal carbides.

Reference 1 - "The effect of adding AlN on the mechanical properties and microstructure of Ti (C, N)-based cermets, Liu Ning et al., Physical and Chemical Testing-Physical Volume, 1997" pointed out that in Ti (C, N)-based metal After ceramics are added with AlN micropowder, a Y′[Ni ₃ (Al,Ti)] phase will be produced in the bonding phase, and the Y′ phase will increase the hindrance of dislocation movement, thereby strengthening the bonding phase, which can improve The strength and hardness of cermets. Reference 2 - "The Thermal Shock Resistance of Ti(C,N)-based Cermets Modified by Nano-TiN, Zhang Xiaobo et al., Cemented Carbide, Volume 24, No. 3, September 2007" pointed out that in Ti(C,N) Adding nano-TiN to N)-based cermets can significantly improve the comprehensive mechanical properties of cermets. The main reasons are 1. The dissolution of nano-TiN in the bonding phase reduces the solubility of the hard phase in the bonding phase, thus The grains of the hard phase are refined; 2. The nano-TiN particles have a pinning effect on the dislocation, which increases the hindrance of the dislocation movement; 3. The nano-TiN is easy to dissolve in the bonding phase, and the TiN is easy to dissolve in the bonding phase. Metal acts as a solid solution strengthener.

Contents of the invention

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

For this reason, the cermet of the present invention comprises:

A hard phase, the hard phase is composed of one or more compounds selected from carbides, nitrides, carbonitrides and carbonitride solid solutions of metals of Group 4, Group 5 and Group 6 of the periodic table , and the metal elements constituting these compounds are mainly Ti;

a binder phase consisting essentially of an iron group metal; and

A strengthening phase, the strengthening phase comprising AlN nanowires and a TiAlN compound formed on the bonding surface of the AlN nanowires and the hard phase compound; the total weight of the Al element in the AlN nanowires and the TiAlN compound per unit metal The proportion by weight of ceramics is >0% and ≤5%.

The study found that the TiAlN compound formed on the bonding surface of the AlN nanowire and the hard phase compound during the sintering process is a stable compound at high temperature, which can effectively isolate the outward diffusion of Ti, N, and C atoms in the hard phase. effect, thereby effectively inhibiting the dissolution and precipitation of Ti, N, and C atoms in the bonding phase, reducing the solubility of titanium carbonitride in the bonding phase, and reducing the dissolution and precipitation of titanium carbonitride in the bonding phase and growing The resulting N decomposition enhances the stability of titanium carbonitride, refines the grains of titanium carbonitride, and improves the hardness and toughness of cermets. At the same time, the AlN nanowires have a fiber-reinforced effect on the cermet, which can further improve 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, bending strength and fracture toughness, and achieves excellent comprehensive mechanical properties. However, tests have also shown that if the total weight of Al elements in AlN nanowires and TiAlN compounds accounts for more than 5% of the weight of the cermet, the increase in brittle phases in the material will reduce 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 Al element in the AlN nanowire and the TiAlN compound preferably accounts for 2%-4% of the weight of the cermet. Tests have shown that when the total weight of Al elements in AlN nanowires and TiAlN compounds is within the above range, Ti(C,N)-based cermets are significantly better than existing metals in terms of hardness, flexural strength and fracture toughness. Ceramics; if the Al content is less than 2%, the effect of strengthening and toughening is not very obvious. If the Al content is higher than 4%, the increase of brittle phases 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 is composed of one or more compounds selected from carbides, nitrides, carbonitrides and carbonitride solid solutions of metals of Group 4, Group 5 and Group 6 of the periodic table , and the metal elements constituting these compounds are mainly Ti;

a binder phase consisting essentially of an iron group metal; and

Strengthening phase, the strengthening phase includes AlN nanowires and a TiAlN compound formed on the bonding surface of the AlN nanowires and the hard phase compound, the total weight of the Al element in the AlN nanowires and the TiAlN compound accounts for The proportion of ceramic weight is less than 5%.

Based on the stated reasons, in the cutting tool of the present invention, the total weight of the Al elements in the AlN nanowires and the TiAlN compound preferably accounts for 2%-4% of the weight of the cermet matrix.

A method for preparing a cermet comprising the steps of:

1) Prepare the powder mixture

Composition and ratio of raw materials (weight percent)

Ti(C,N) powder: 40%～60%

Iron group metals: 10% to 20%

AlN nanowires: 3% to 6%

Transition metal carbides: the rest

According to the above components and proportions, Ti(C,N) powder, iron group metals and transition group metal carbides are pulverized and mixed, then AlN nanowires are added and mixed to obtain a powder mixture;

2) Molding

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

3) Sintering

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

After testing, through the above preparation method, the TiAlN compound will be formed on the bonding surface of the AlN nanowire and the hard phase compound. Moreover, in the prepared Ti(C,N)-based cermet, the total weight of the Al element in the AlN nanowire and the TiAlN compound accounts for 2%-4% of the weight of the cermet.

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

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

Further, the transition group metal carbide is composed of WC, TaC, NbC and Mo ₂ C, wherein the sum of WC, TaC and NbC by weight accounts for 10%-20% of the powder mixture, and the rest is WC.

Pressure forming can choose methods such as molding, isostatic pressing, extrusion and rolling.

Compared with reference 1, the position, shape and structure of the strengthening phase formed in the Ti(C,N)-based cermet of the present invention are different, and the strengthening mechanism of the Ti(C,N)-based cermet also has different. In addition, it can also be seen from the specific implementation that will be given below in this specification that the Ti(C,N)-based cermet of the present invention is significantly higher than the Ti(C,N)-based cermet in Reference 1 in terms of hardness and flexural strength. ) hardness and flexural strength of the base cermet.

Compared with reference document 2, the Ti(C,N)-based cermet of the present invention isolates the Ti, N, and C atoms in the hard phase from the outside through the TiAlN compound formed on the bonding surface of the AlN nanowire and the hard phase compound. diffusion to achieve the purpose of refining the grains of the hard phase, while Reference 2 achieves the purpose of refining the grains of the hard phase through the dissolution and occupancy of nano-TiN in the binder phase, so the two also have the essence difference.

Description of drawings

FIG. 1 is a graph showing the variation of material hardness versus the amount of Al nanowires added in Test Examples 1-8 of the present application.

Fig. 2 is a graph showing the variation of the flexural strength of the materials in Test Examples 1-8 of the present application with respect to the addition amount of Al nanowires.

Fig. 3 is a graph showing the variation of the flexural strength of the materials in Test Examples 1-8 of the present application with respect to the amount of Al nanowires added.

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

The unit of the horizontal axis in Fig. 1, Fig. 2 and Fig. 3 is percentage by weight.

Detailed ways

<Test example>

Manufacture Ti(C,N)-based cermets, and then test the hardness, fracture toughness and flexural strength of these Ti(C,N)-based cermets.

The basic steps of the test are:

1) Prepare the powder mixture

Weigh the raw materials according to the set components and proportions, and carry out mixed ball milling for 60-90 hours in a drum-type ball mill at a ball-to-material ratio (6-8): 1, at a speed of 20-40 rpm, to prepare powder mix.

The addition of AlN nanowires was scheduled to be completed at the beginning of the last 10 hours of ball milling.

2) Molding

Add molding agents such as paraffin wax and PEG to the powder mixture, stir evenly, sieve and mold in a mold to form a green compact, and the molding pressure is 100Mpa to 300Mpa.

3) Sintering

The above-mentioned compact is placed in a vacuum or a protective atmosphere for sintering. During sintering, it is kept at 1380°C-1480°C for 1 hour to 3 hours, and the Ti(C,N)-based cermet is obtained after cooling.

[Table 1]

Components and proportions of raw materials (percentage by weight).

Table 1

illustrate:

1. Test numbers 1-8 correspond to test numbers 1-8 in the following tables respectively.

2. In the tests numbered 1-8, the addition amount of AlN nanowires increased by 1% from 0% to 7% at last.

3. For the convenience of comparison, the transition group metal carbides in the tests No. 1-8 are all selected from WC, NbC and Mo ₂ C. However, those skilled in the art can clearly determine that other transition metal carbides such as TaC, VC, Cr ₃ C ₂ and the like can be used as additives.

4. For the convenience of comparison, the raw materials of the bonding phase in the tests No. 1-8 are all selected from Co and Ni. However, those skilled in the art can clearly determine 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 contents of each component in the tests numbered 1-8 are all selected within the range defined by the present invention.

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

[Table 2]

Roller ball mill operating parameters

Table 2

[table 3]

Sintering conditions

table 3

[Table 4]

test results

Table 4

In addition, it was found by X-ray photoelectron spectroscopy (XPS) detection that, in the samples of test numbers 1-3 and 5-8, TiAlN compounds were formed on the bonding surfaces of AlN nanowires and hard phase compounds.

Test description:

1. After calculation, the total weight of the AlN nanowires in the cermet obtained in the test No. 4 and the Al element in the TiAlN compound accounted for about 2% of the weight of the cermet; the AlN nanowires in the cermet obtained in the test No. 7 And the total weight of the Al element in the TiAlN compound accounts for about 4% of the weight of the cermet per unit. The proportion is about 4.6%.

2. In Figure 1, the hardness of the cermet obtained from the test No. 6 suddenly decreased, which was related to the decrease in the amount of Ti(C, N) powder added; in Figure 3, the fracture toughness of the cermet obtained from the test No. 5 decreased suddenly, which is It is related to the reduction of the addition of binder phase metal. Excluding the influence of these factors, the hardness, flexural strength and fracture toughness of the material all showed an increasing trend when the addition of AlN nanowires increased from 0% to 5%. The preferred addition amount of AlN nanowires in the present invention is 3% to 6%. In this range, the hardness, bending strength and fracture toughness of the material are obviously better than the existing cermets.

Claims (10)

1. sintering metal comprises:

The hard phase, said hard is made up of one or more compounds in the carbide that is selected from the periodic table of elements the 4th family, the 5th family and the 6th family's metal, nitride, carbonitride and the carbonitride sosoloid, and the metallic element that constitutes these compounds is mainly Ti;

Bonding phase saidly bondingly mainly is made up of the iron family metal mutually; And

Strengthening phase; Said strengthening phase comprises the AlN nano wire and is formed at said AlN nano wire and the hard TiAlN compound on the compound bonding surface mutually, the gross weight of the Al element in said AlN nano wire and the TiAlN compound account for per unit sintering metal weight ratio＞0% and≤5%.

2. sintering metal as claimed in claim 1 is characterized in that: the gross weight of the Al element in said AlN nano wire and the TiAlN compound accounts for 2%～4% of per unit sintering metal weight.

3. according to claim 1 or claim 2 sintering metal, it is characterized in that: said iron family metal is selected from one or more among Co, Ni, Fe, the Cu.

4. cutting tool has the sintering metal matrix, and said sintering metal matrix comprises:

The hard phase, said hard is made up of one or more compounds in the carbide that is selected from the periodic table of elements the 4th family, the 5th family and the 6th family's metal, nitride, carbonitride and the carbonitride sosoloid, and the metallic element that constitutes these compounds is mainly Ti;

Bonding phase saidly bondingly mainly is made up of the iron family metal mutually; And

Strengthening phase; Said strengthening phase comprises the AlN nano wire and is formed at said AlN nano wire and the hard TiAlN compound on the compound bonding surface mutually that the gross weight of the Al element in said AlN nano wire and the TiAlN compound accounts for the ratio of per unit sintering metal weight below 5%.

5. cutting tool as claimed in claim 4 is characterized in that: the gross weight of the Al element in said AlN nano wire and the TiAlN compound accounts for 2%～4% of per unit ceramet group body weight.

6. like claim 4 or 5 described cutting tools, it is characterized in that: said iron family metal is selected from one or more among Co, Ni, Fe, the Cu.

7. ceramic-metallic preparation method, the step that comprises is:

1) preparation powdered mixture

The component of raw material and proportioning (weight percent)

Ti (C, N) powder: 40%～60%

Iron family metal: 10%～20%

AlN nano wire: 3%～6%

Transition metal carbides: all the other

According to above-mentioned component and proportioning, with Ti (C, N) powder, iron family metal and transition metal carbides are pulverized and are mixed, and add the AlN nano wire then, mixed powdered mixture;

2) moulding

Through pressure forming above-mentioned powdered mixture is processed pressed compact;

3) sintering

Place vacuum or protective atmosphere to carry out sintering above-mentioned pressed compact, be incubated 1 hour～3 hours down at 1380 ℃～1480 ℃ during sintering, promptly obtain said sintering metal after the cooling.

8. ceramic-metallic preparation method as claimed in claim 7 is characterized in that: said iron family metal is selected from one or more among Co, Ni, Fe, the Cu.

9. like claim 7 or 8 described ceramic-metallic preparing methods, it is characterized in that: said transition metal carbides is selected from WC, TaC, NbC, Mo ₂Among the C one or more.

10. the ceramic-metallic preparation method who states like claim 9 is characterized in that: said transition metal carbides is by WC, TaC, NbC and Mo ₂C forms, and wherein, WC, TaC and NbC weight sum account for 10%～20% of said powdered mixture, and all the other are WC.

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