WO2020103235A1

WO2020103235A1 - Transition metal boride hard ceramic material, preparation method therefor and application thereof

Info

Publication number: WO2020103235A1
Application number: PCT/CN2018/121024
Authority: WO
Inventors: 龙莹; 黄路江; 车金涛; 林华泰
Original assignee: 广东工业大学
Priority date: 2018-11-19
Filing date: 2018-12-14
Publication date: 2020-05-28
Also published as: CN109437915A

Abstract

A transition metal boride hard ceramic material, a preparation method therefor and an application thereof. The transition metal boride hard ceramic material is Os_I-xMT_xB₂, wherein MT is Re, W or Ir, and x is 0.01-0.5; under an inert gas, a mechanochemical method is used to mix Os, MT and B powder to form an Os_I-xMT_xB₂ powder; a sintering aid Ni is added to the Os_I-xMT_xB powder, sieving treatment is performed after milling, and the Ni-containing Os_I-xMT_xB₂ powder is sintered at 1400-1800°C so as to obtain the material. By means of adding Ni as a sintering aid, bulk sintering temperature is reduced, a bulk material having a relatively high density is obtained, and the mechanical properties of the bulk material are improved. The ceramic material may be used in industrial fields such as cutting tools and grinding.

Description

Transition metal boride hard ceramic material and preparation method and application thereof

Technical field

The present invention belongs to the technical field of inorganic non-metallic materials, and more specifically, relates to a transition metal boride hard ceramic material Os _1-x MT _x B ₂ (MT = Re, W, Ir) and a preparation method and application thereof.

Background technique

With the rapid development of industrialization, the demand for high-performance materials is increasing. Superhard materials are widely used in many fields such as precision manufacturing, aerospace, machinery and medical treatment, and are known as industrial "teeth". At present, the main superhard materials are diamond and cubic boron nitride, but the thermal stability and chemical inertness of diamond are relatively poor, and the cutting of iron-containing workpieces is easy to graphitize, and its use range is limited to a certain extent; cubic boron nitride is currently The second hardest material, although it can replace diamond on the cutting iron-containing workpieces, but the synthesis of cubic boron nitride requires high temperature and high pressure, and the cost is relatively high. Therefore, there is an urgent need to find a new type of super-hard material.

The research of new superhard materials mainly includes B-C-N-O series and transition metals (Re, Os, Ru, Ir) and light elements (B, N, C) series. Although great progress has been made in the research of BCNO series compounds, the synthesis conditions are harsh and the manufacturing cost is too high. Therefore, in order to find super-hard materials that are inexpensive and expensive, many researchers have devoted themselves to the transition metals and light elements. the study.

In the study of transition metal elements and light elements, osmium has attracted attention because of its highest valence electron density. The researchers predicted that OsB ₂ has three types of structures through first-principles calculations: (1) RuB ₂ type orthogonal structure (2) ReB ₂ type hexagonal structure (3) AlB ₂ type hexagonal structure, and the calculation results show that the hexagonal structure The hardness is higher than the orthogonal structure. However, since the ReB ₂ type hexagonal structure OsB ₂ is a metastable phase, all the OsB ₂ prepared by experiments have been RuB ₂ type orthogonal structures. As described in US Patent US09701542B2, in 2014, xie et al. Synthesized the ReB ₂ type hexagonal structure OsB ₂ for the first time by mechanochemical methods, but they found that part of the ReB ₂ type hexagonal structure OsB _{2 was} transformed into orthogonal in the subsequent spark plasma sintering process. Structure, the occurrence of phase change will cause the performance of the material to decrease. The researches of Chinese Patent CN107043260A and Chinese Patent CN107188565A found that ReB ₂ type hexagonal structure OsB ₂ undergoes a phase transition to an orthogonal structure at above 600 ℃. By doping a certain amount of rhenium (Re), With iridium (Ir) or tungsten (W) elements, a stable ReB ₂ type hexagonal structure third element doped OsB ₂ can be obtained. At present, Os _1-x MT _x B ₂ (MT = Re, W, Ir, etc.) transition metal boride hard material without sintering aid, through SPS sintering, hot pressing sintering and pressureless sintering block The density of the material is not high, and the corresponding mechanical properties are also very low.

Summary of the invention

In order to solve the above shortcomings and shortcomings of the prior art, the present invention provides a transition metal boride hard material. The material has the advantages of high density and excellent mechanical properties.

Another object of the present invention is to provide a method for preparing the above transition metal boride hard material. This method improves the density and mechanical properties of Os _1-x MT _x B ₂ (MT = Re, W, Ir) transition metal boride hard materials by adding sintering aid Ni.

Another object of the present invention is to provide the application of the above transition metal boride hard material.

The object of the present invention is achieved by the following technical solutions:

A transition metal boride hard ceramic material, the transition metal boride hard ceramic material is Os _1-x MT _x B ₂ , where MT is Re, W or Ir; x is 0.01 to 0.5;

The transition metal boride hard ceramic material is made of Os, MT and B powder under argon gas by mechanochemical method to make Os _1-x MT _x B ₂ powder, wherein Os _: MT: B mole in the mixed powder The ratio is (0.5 ～ 0.99) :( 0.01 ～ 0.5) :( 2.25 ～ 5); Add the sintering aid Ni to Os _1-x MT _x B ₂ powder, grind and sieve to treat Os ₁ containing Ni _-x MT _x B ₂ powder is obtained by sintering at 1400 ～ 1800 ℃.

Preferably, the addition amount of the sintering aid Ni is 1-12 wt.% Of the Os _1-x MT _x B ₂ powder; the B powder is amorphous, and the molar ratio of Os, MT and B is 0.9: 0.1: (2.25 ～ 5).

Preferably, the density of the transition metal boride hard ceramic material is 85-99%, and the Vickers hardness value of the transition metal boride hard ceramic material is 1700-4000 Hv.

Preferably, the main phase of the transition metal boride hard ceramic material has a hexagonal structure and Os _1-x MT _x B ₂ is ReB ₂ type.

The preparation method of the transition metal boride hard ceramic material includes the following specific steps:

S1. Under inert gas, mix Os, MT and B powder by mechanochemical method to make Os _1-x MT _x B ₂ powder;

S2. Adding sintering aid Ni to Os _1-x MT _x B ₂ powder, and then sieving after grinding;

S3. The Ni _- containing Os _1-x MT _x B ₂ powder obtained in step S2 is obtained by sintering at 1400-1800 ° C.

Preferably, the equipment used in the mechanochemical method in step S1 is a high-energy ball mill, a vibrating ball mill, a planetary ball mill, or a plasma assisted high-energy ball mill.

Preferably, the milling time in step S2 is 20-30 min, and the hole diameter of the sieve is 100-200 mesh.

Preferably, the sintering method in step S3 is pressureless sintering, hot press sintering or spark plasma sintering.

More preferably, the temperature increase rate in the pressureless sintering is 3-15 ° C / min, and the holding time is 1-2h; the temperature increase rate in the hot pressure sintering is 5-15 ° C / min, and the sintering pressure is 20-70MPa , The sintering pressure should be as large as possible in the interval of 20MPa-70MPa, and the holding time for heat preservation should be 1 ~ 2h; the heating rate of the discharge plasma sintering is 100 ~ 200 ℃ / min, the sintering pressure is 20 ~ 70MPa, heat preservation The pressure holding time is 10 ～ 15min.

The application of the transition metal boride hard ceramic material in the field of cutting tools or grinding industry.

Preferably, the cutting tool is a dry cutting tool containing ferrous metal.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the present invention, an appropriate amount of Ni is selected to obtain a transition metal boride hard ceramic material Os _1-x MT _x B ₂ (MT = Re, W, Ir) with high density, high hardness and controllable bulk main phase ), Os _1-x MT _x B ₂ whose main phase has a hexagonal structure is of ReB ₂ type.

2. In the present invention, by controlling the sintering parameters, a higher density of bulk materials is obtained, and the density is between 85 and 99%.

3. The present invention intends to use the solid-liquid sintering principle to promote the compaction of the bulk during the sintering process by establishing the relationship between the sintering process and the amount of Ni added-the bulk material microstructure and the density-bulk material mechanical properties. The method of chemical sintering is used to guide the adjustment of process parameters and the amount of Ni added to optimize the main phase, crystal structure, density and hardness of the material.

4. The transition metal boride hard ceramic material Os _1-x MT _x B ₂ (MT = Re, W, Ir) prepared by the present invention can be effectively used for cutting tools, especially high-speed dry cutting of ferrous metals.

BRIEF DESCRIPTION

FIG. 1 is an XRD pattern of Os-Re-B mixed powder high-energy ball milling in Example 1 and Comparative Example 1 after 40 hours.

FIG 2 is a Os _0.9 Re _0.1 B ₂ powder of Comparative Example 1 after 40h ball milling in Example 1 and Os _0.9 Re _0.1 B ₂ powder added 3wt.% Ni sintering aid was 1750 ℃, after hot pressing sintering 30MPa Block XRD pattern.

FIG 3 is a powder of Comparative Example ₂ Os _powder _0.9 Re _0.1 B 1 and Example 1 Os _0.9 Re _0.1 B added 3wt.% Ni sintering aid was 1750 ℃, SEM cross-section of the block after sintering, and hot pressing 30MPa EDS photos.

4 is a cross-sectional scanning photograph of a block of Os _0.9 Re _0.1 B ₂ with 3 wt.% Ni sintering aid added to the Os _0.9 Re _0.1 B ₂ powder in Example 1. FIG.

FIG 5 is a Comparative Example 1 was added in 3 wt Os _0.9 Re _0.1 B ₂ powder in Example 1 Os _0.9 Re _0.1 B ₂ powder.% Ni sintering aid was 1750 ℃, block polished surface after hot press sintering 30MPa Backscatter.

detailed description

The content of the present invention is further described below with reference to specific embodiments, but it should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

Example 1

(1) Taking Os _0.9 Re _0.1 B ₂ powder as an example, Os _0.9 Re _0.1 B ₂ powder was synthesized using a high-energy ball mill with a model of 8000M from the US SPEX company, and then an appropriate amount of Ni powder was added as a sintering aid for densification and sintering. First, in a glove box filled with argon, high-purity osmium powder (Os), rhenium powder (Re) (where the molar ratio of osmium powder to rhenium powder is 9: 1) and boron (B) powder are stoichiometric ratio 1: 3 ingredients. The grinding balls used are made of tungsten carbide, the number is 6, the diameter is 11.20mm, and the ball to material ratio is 4: 1.

(2) Fix the ball mill jar with the powder and balls installed on the fixture of the high-energy ball mill, and perform ball milling for 40 hours. To prevent the motor from overheating, set the machine to stop for 20 minutes every 1 hour.

(3) Take a certain amount of Os-Re-B mixed powder after 40 hours of high-energy ball milling, add Ni powder with a mass fraction of 3%, use a mortar to grind and mix evenly, and then sieve the mixed powder, and sieve The specification is 200 mesh.

(4) Os _0.9 Re _0.1 B ₂ powder added with 3wt.% Ni was sintered in a hot-press furnace at 1750 ° C, 30MPa, and kept under heat and pressure for 1h to obtain a bulk material of Os _0.9 Re _0.1 B ₂ added with 3wt.% Ni.

Comparative Example 1

(1) Taking Os _0.9 Re _0.1 B ₂ powder as an example, Os _0.9 Re _0.1 B ₂ powder was synthesized using a high-energy ball mill model 8000M of the American SPEX company, and then densified and sintered. First, in a glove box filled with argon, high-purity osmium powder (Os), rhenium powder (Re) (where the molar ratio of osmium powder to rhenium powder is 9: 1) and boron (B) powder are stoichiometric ratio 1: 3 ingredients. The grinding balls used are made of tungsten carbide, the number is 6, the diameter is 11.20mm, and the ball to material ratio is 4: 1.

(3) Take a certain amount of Os-Re-B mixed powder after 40 hours of high-energy ball milling, and then sieve it, the screen size is 200 mesh.

(4) Os _0.9 Re _0.1 B ₂ powder obtained after high-energy ball milling for 40 h was sintered in a hot-press furnace at 1750 ° C. and 30 MPa, and kept under heat and pressure for 1 h to obtain Os _0.9 Re _0.1 B ₂ bulk material.

FIG. 1 is an XRD pattern of the Os-Re-B mixed powder in Example 1 and Comparative Example 1 after high-energy ball milling for 40 hours, where (Os, Re = 9: 1): B = 1: 3. It can be seen from FIG. 1 that the mixed powder under the stoichiometric ratio of Os-Re-B is _0.9: _0.1: ₃ , after high-energy ball milling for 40h, the main phase of the product obtained is ReB ₂ type Os _0.9 Re _0.1 with hexagonal structure B ₂ powder. In addition, there is a small amount of WC in the synthesized powder, which may come from the pollution of the ball mill jar and the ball.

Fig. 2 is the block of the Os _0.9 Re _0.1 B ₂ powder after being ball milled for 40 hours in Comparative Example 1 and the Os _0.9 Re _0.1 B ₂ powder in Example 1 after adding 3wt.% Ni sintering aid and sintered by hot pressing at 1750 ℃ and 30MPa XRD pattern. It can be seen from (a) in FIG. 2 that the Os _0.9 Re _0.1 B ₂ powder and the Os _0.9 Re _0.1 B ₂ powder after 40 h of ball milling are added with 3wt.% Ni for hot-press sintering at 1750 ° C and 30 MPa. The XRD after sintering of both There are only Os _0.9 Re _0.1 B ₂ diffraction peaks with hexagonal structure in the spectrum, indicating that the addition of the sintering aid Ni did not affect the change of its main phase. Combined with (b) in Fig. 2, it can be seen that there is a certain amount of shift in the XRD diffraction peak of the bulk with the addition of 3wt.% Ni sintering aid, which may be due to the solid solution of the sintering aid Ni added to Os _0.9 Re _0.1 In the B ₂ crystal, lattice distortion is caused, and peak position shift occurs.

FIG 3 is a powder of Comparative Example ₂ Os _powder _0.9 Re _0.1 B 1 and Example 1 Os _0.9 Re _0.1 B added 3wt.% Ni sintering aid was 1750 ℃, SEM cross-section of the block after sintering, and hot pressing 30MPa EDS photos. Among them, (a) and (b) are without added Ni, and (c) and (d) are added with 3wt.% Ni. It can be seen from Figures 3 (a) and (c) that the samples sintered without adding Ni and adding 3wt.% Ni sintering aid have similar microstructures, and the fracture forms are all transcrystalline fractures, and the crystal grains of the two groups of samples are mostly Bar-shaped crystals and grains are staggered and disordered, as can be seen from Figure 3, there are pores, the density is not high, but the density of the block with 3wt.% Ni added is higher than that without the block, and the density The values are 79% and 85.3%, respectively. (b) and (d) are partially enlarged views of (a) and (b), respectively. It can be seen from the figure that the grains in FIG. 3 (b) are sintered together, and combined with the corresponding EDS, it can be seen that only the grain boundaries between Excess B exists, there is no other second phase; and at the grain boundary in FIG. 3 (d) with the addition of sintering aid Ni, combined with its corresponding EDS diagram, it can be seen that except for the presence of excess B at the grain boundary, Ni element is also present.

Fig. 4 is a scanning photograph of the cross-section of the Os _0.9 Re _0.1 B ₂ block with 3 wt.% Ni sintering aid added to the Os _0.9 Re _0.1 B ₂ powder in Example 1, and it can be seen from Fig. 4 that Os and Re are present in the sintered sample , B, O and Ni elements, and the distribution of each element is uneven, in which Ni element is mainly distributed at the grain boundary. Comparative Example 5 is added 1 Os _0.9 Re _0.1 B ₂ powder in Example 1 Os _0.9 Re _0.1 B ₂ powder 3wt.% Ni sintering aid was 1750 ℃, block polished surface after hot press sintering back 30MPa scattering. Among them, (a) no added Ni and (b) added 3wt.% Ni. It can be seen from Figure 5 that the grain size of the two groups of samples is large and there are some black areas, which may be the accumulation of excess boron powder to generate black areas. It is also possible that the gas generated by the boron powder volatilization during the sintering process is too late to be discharged and the pores formed.

Example 3

The difference from Example 1 is that 6wt.% Ni is added as a sintering aid.

Example 4

The difference from Example 1 is that 9wt.% Ni is added as a sintering aid.

Example 5

The difference from Example 1 is that 12 wt.% Ni is added as a sintering aid.

Example 6

The difference from Example 1 is that Os _0.9 Re _0.1 B ₂ powder added with 3wt.% Ni is sintered with SPS at 1600 ° C, 40MPa, and holding pressure for 10 minutes.

Example 7

The difference from Example 1 is that Os _0.9 Re _0.1 B ₂ powder added with 3wt.% Ni is sintered in a pressure-free furnace at 1700 ° C and a heat preservation pressure for 90 minutes.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above examples, and any other changes, modifications, substitutions, combinations and changes made without departing from the spirit and principle of the present invention The simplifications should all be equivalent replacement methods, which are all included in the protection scope of the present invention.

Claims

A transition metal boride hard ceramic material, characterized in that the transition metal boride hard ceramic material is Os 1-x MT x B 2 , wherein MT is Re, W or Ir; x is 0.01 to 0.5 ;

The transition metal boride hard ceramic material is made of Os, MT and B powder under argon gas by mechanochemical method to make Os 1-x MT x B 2 powder, wherein Os : MT: B mole in the mixed powder The ratio is (0.5 ～ 0.99) :( 0.01 ～ 0.5) :( 2.25 ～ 5); Add the sintering aid Ni to Os 1-x MT x B 2 powder, grind and sieve to treat Os 1 containing Ni -x MT x B 2 powder is obtained by sintering at 1400 ～ 1800 ℃.
The transition metal boride hard ceramic material according to claim 1, wherein the addition amount of the sintering aid Ni is 1-12wt.% Of the Os 1-x MT x B 2 powder; the B The powder is amorphous, and the molar ratio of Os, MT and B is 0.9: 0.1: (2.25 to 5).
The transition metal boride hard ceramic material according to claim 1, wherein the density of the transition metal boride hard ceramic material is 85-99%, and the transition metal boride hard ceramic material The Vickers hardness value is 1700 ～ 4000Hv.
The transition metal boride hard ceramic material according to claim 1, wherein the main phase of the transition metal boride hard ceramic material has a hexagonal structure and Os 1-x MT x B 2 is of ReB 2 type.
The method for preparing a transition metal boride hard ceramic material according to any one of claims 1 to 4, characterized in that it includes the following specific steps:

S1. Under inert gas, mix Os, MT and B powder by mechanochemical method to make Os 1-x MT x B 2 powder;

S2. Adding sintering aid Ni to Os 1-x MT x B 2 powder, and then sieving after grinding;

S3. The Ni - containing Os 1-x MT x B 2 powder obtained in step S2 is sintered at 1400-1800 ° C. to obtain a transition metal boride hard ceramic material.
The method for preparing a transition metal boride hard ceramic material according to claim 5, wherein the equipment used in the mechanochemical method in step S1 is a high-energy ball mill, a vibrating ball mill, a planetary ball mill or a plasma assisted high-energy ball mill .
The method for preparing a transition metal boride hard ceramic material according to claim 5, characterized in that, in step S2, the milling time is 20-30 min, and the pore diameter of the sieve is 100-200 mesh.
The method for preparing a transition metal boride hard ceramic material according to claim 5, wherein the sintering method in step S3 is pressureless sintering, hot press sintering or spark plasma sintering.
The method for preparing a transition metal boride hard ceramic material according to claim 8, characterized in that, the temperature increase rate in the pressureless sintering is 3 to 15 ° C / min, the holding time is 1 to 2h; The heating rate during sintering is 5 ～ 15 ℃ / min, the sintering pressure is 20 ～ 70MPa, and the holding time is 1 ～ 2h; the heating rate during spark plasma sintering is 100 ～ 200 ℃ / min, and the sintering pressure is 20 ～ 70MPa , Holding time is 10 ～ 15min.
The use of the transition metal boride hard ceramic material according to any one of claims 1 to 4 in the field of cutting tools or grinding industry.