CN114318038A

CN114318038A - Boride modified Mo2FeB2Base cermet and method for preparing same

Info

Publication number: CN114318038A
Application number: CN202111452354.6A
Authority: CN
Inventors: 刘文俊; 李延凤; 丰平; 余海洲; 黄威
Original assignee: China Three Gorges University CTGU
Current assignee: China Three Gorges University CTGU
Priority date: 2021-12-01
Filing date: 2021-12-01
Publication date: 2022-04-12
Anticipated expiration: 2041-12-01
Also published as: CN114318038B

Abstract

The invention discloses boride modified Mo₂FeB₂A base cermet and a preparation method thereof. Using Mo, FeB, Fe, Cr, Ni, C and LaB₆Mixing, ball-milling, drying, pressing, vacuum sintering and cooling the powder raw materials to obtain Mo₂FeB₂Hardness of base cermet, cermet88.5-90.3 HRA, the bending strength of 1691.93-2099.58MPa, and the fracture toughness of 22.7-27.6MPa^1/2. The invention has simple components, convenient preparation process and lower cost. The boride of the rare earth element is added, the crystal boundary is purified by the rare earth element, and other impurities are not doped in the boride of the rare earth element, so that the comprehensive mechanical property of the metal ceramic is greatly improved. And a rapid cooling mode is utilized for cooling, so that a part of Fe-based bonding phase structure is changed, and the comprehensive performance of the Fe-based bonding phase structure is improved. Meanwhile, the sintering period is shortened, and the time cost is reduced.

Description

Boride modified Mo2FeB2Base cermet and method for preparing same

Technical Field

The invention belongs to the technical field of metal ceramics and preparation, and particularly relates to boride modified Mo₂FeB₂A base cermet and a preparation method thereof.

Background

The ternary boride cermet has the characteristics of low density, high hardness, good conductivity, and good wear resistance and corrosion resistance. At present, the boronizing of ternary boride cermets has been applied to the fields of injection molding dies, nonferrous metal processing tools, lining plates of kilns and the like.

Mo₂FeB₂Compared with other ternary boride cermets, the base cermet has low cost and more excellent comprehensive mechanical property, the density is only 3/5 of common hard alloy, and the base cermet can be tightly combined with a steel matrix to form a coating material, so that the base cermet becomes an ideal material for preparing tools, dies and wear-resistant parts, and is widely applied to cutting tools, hot extrusion grinding tools, steel part coatings and the like.

To promote Mo₂FeB₂The comprehensive mechanical properties of base cermet, some researchers studied Mo in different alloy element pairs₂FeB₂The influence of comprehensive mechanical properties of the base metal ceramic rarely can improve the bending strength, hardness and fracture toughness of the metal ceramic at the same time. A Chinese patent with the application number of 201910110152.X discloses rare earth element modified Mo₂FeB₂A base cermet is prepared from Mo powder, FeB powder and Fe powder through respectively doping La powder and Y powder, ball grinding, baking, pressing and sintering₂FeB₂A base cermet. The maximum hardness of the metal ceramic obtained by the technology is 89.1HRA, and the maximum three-point bending strength is 1540.7 MPa. The three-point bending strength of the metal ceramic obtained by the technical scheme limits the application of the metal ceramic in a high-strength service environment, and the fracture toughness is not described in detail. Researchers have studied W on multi-step sintered Mo₂FeB₂Mechanical property of base cermetThe influence of energy, the doping of W obviously reduces the hardness of the metal ceramic, increases the fracture toughness of the metal ceramic, and slightly improves the bending strength, so that the W is the same as other metal elements and can not simultaneously improve the hardness and the fracture toughness of the metal ceramic.

In addition, in the original Mo₂FeB₂In the preparation process of the base metal ceramic, a furnace cooling method is mostly adopted in the vacuum sintering preparation method, and the Fe-based binding phase has no obvious structural change in the furnace cooling process. In the heat treatment quenching process of steel, residual austenite or martensite can be obtained according to different contents of C in the material, the residual austenite can improve the toughness of the material, and the martensite can improve the hardness of the material. In the presence of Mo₂FeB₂The rapid cooling sintering process is adopted in the base metal ceramic, which is similar to the heat treatment quenching process of steel, and the performance of the metal ceramic is improved by promoting the phase change of the Fe-based binding phase.

Disclosure of Invention

The invention aims to solve the technical problem of providing boride modified Mo aiming at the defects of the prior art₂FeB₂The base cermet and its preparation process can raise Mo content effectively₂FeB₂The metal ceramic has comprehensive mechanical properties, simple components, convenient preparation process, short sintering period and low cost, and can meet a certain material service environment.

The invention adopts the following technical scheme:

boride modified Mo₂FeB₂The preparation method of base cermet comprises mixing Mo, FeB, Fe, Cr, Ni, C and LaB with purity not lower than 99.5%₆Mixing the powder, adding absolute ethyl alcohol for ball milling, drying and sieving the wet material subjected to ball milling, then performing compression molding, sintering in a vacuum sintering furnace, and cooling along with the furnace to obtain Mo with excellent mechanical property₂FeB₂A base cermet.

Specifically, mixing the original powder according to the mass ratio: 44.4 percent of Mo; 29.7 percent of FeB; 19.125-20.125% of Fe; 2.5 percent of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:0~1.0%。

Furthermore, the ball milling adopts a wet milling mode, absolute ethyl alcohol is added as a ball milling medium, the mass ratio of the addition amount of the absolute ethyl alcohol to the powder is 1:1, the ball-material ratio is 5:1, the ball milling rotating speed is 200r/min, and the ball milling time is 36 h.

Specifically, the slurry after ball milling is dried in a vacuum drying oven, wherein the temperature of the vacuum drying oven is 80 ℃, and the time is 2 hours.

Further, the dried powder is pressed and molded, the molding pressure is 200MPa, and the pressure maintaining time is45 s.

Concretely, the pressed metal ceramic green body is put into a vacuum sintering furnace for sintering, and the vacuum degree is 10^-1100Pa, the sintering process mainly comprises the following stages:

a. room temperature-1035 ℃: the heating rate is 5 ℃/min, and the heat preservation time is 120 min;

b.1035 ℃ -1135 ℃: the heating rate is 1.5 ℃/min, and the heat preservation time is 60 min;

c.1135 ℃ -1230 ℃: the heating rate is 1.25 ℃/min, and the heat preservation time is 40 min;

d.1230-750 ℃: the average cooling speed is respectively 4 ℃/min, 8 ℃/min and 12 ℃/min;

e.750 ℃ -room temperature: the average cooling speed is respectively 1.2 ℃/min, 6.5 ℃/min and 8.5 ℃/min to obtain Mo₂FeB₂A base cermet.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention uses Mo, FeB, Fe, Cr, Ni, C and LaB₆Preparation of Mo from powder₂FeB₂The base metal ceramic has simple components, convenient preparation process and lower cost.

(2) The invention utilizes the rare earth effect of the rare earth element in the rare earth oxide to purify the crystal boundary, and oxygen element and impurities in the metal ceramic generate oxide to be discharged, thereby improving the comprehensive mechanical property of the metal ceramic and meeting certain service conditions of the material.

(3) The rapid cooling mode is adopted, the sintering time of the metal ceramic is shortened, the time cost is reduced, the sintering period is accelerated, the rapid cooling mode can enable part of Fe-based bonding phase structure to generate phase change, and the comprehensive performance of the material is improved.

The technical solution of the present invention is further described in detail by the following examples.

Drawings

FIG. 1 shows Mo obtained in examples 1 to 7 of the present invention₂FeB₂And (3) a base cermet microstructure diagram.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments, but the scope of the present invention is not limited to the following specific examples.

Example 1

Boride modified Mo₂FeB₂The base metal ceramic is prepared by mixing, ball milling, drying, molding and vacuum sintering raw materials, and comprises the following steps:

s1, adding Mo, FeB, Fe, Cr, Ni, C and LaB with the purity of not less than 99.5%₆Mixing the powder, wherein the mixing mass ratio is as follows: 44.4 percent of Mo; 29.7 percent of FeB; 20.125% of Fe and 2.5% of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:0%。

S2, pouring the mixed slurry into a ball milling tank, adding absolute ethyl alcohol as a ball milling medium, wherein balls for ball milling are hard alloy balls, the ball-material ratio is 5:1, the ball milling rotating speed is 200r/min, and the ball milling time is 36 h.

S3, placing the ball-milled slurry into a vacuum drying oven, wherein the temperature of the vacuum drying oven is 80 ℃, and the drying time is 2 hours.

And S4, pressing and forming the dried powder, wherein the forming pressure is 200MPa, and the pressure maintaining time is45 s.

S5, putting the pressed metal ceramic green body into a vacuum sintering furnace for sintering, wherein the vacuum degree is 10^-1100Pa, the sintering process mainly comprises the following stages:

d. 1230-750 ℃ C: the average cooling speed is4 ℃/min respectively;

e.750 ℃ -room temperature: the average cooling speed is 1.2 ℃/min respectively to obtain Mo₂FeB₂A base cermet.

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The properties of the obtained metal ceramic are as follows: the hardness is 89.8HRA, the bending strength is 2099.58MPa, and the fracture toughness is 22.7MPa^1/2。

Example 2

s1, adding Mo, FeB, Fe, Cr, Ni, C and LaB with the purity of not less than 99.5%₆Mixing the powder, wherein the mixing mass ratio is as follows: 44.4 percent of Mo; 29.7 percent of FeB; 19.875% of Fe and 2.5% of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:0.25%。

d. 1230-750 ℃ C: the average cooling speed is4 ℃/min respectively;

e.750 ℃ -room temperature: averageThe cooling speed is 1.2 ℃/min respectively to obtain Mo₂FeB₂A base cermet.

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The properties of the obtained metal ceramic are as follows: the hardness is 89.2HRA, the bending strength is 1889.99MPa, and the fracture toughness is 25.9MPa^1/2。

Example 3

s1, adding Mo, FeB, Fe, Cr, Ni, C and LaB with the purity of not less than 99.5%₆Mixing the powder, wherein the mixing mass ratio is as follows: 44.4 percent of Mo; 29.7 percent of FeB; 19.625 percent of Fe and 2.5 percent of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:0.50%。

d. 1230-750 ℃ C: the average cooling speed is4 ℃/min respectively;

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The properties of the obtained metal ceramic are as follows: the hardness is 89.5HRA, the bending strength is 1949.65MPa, and the fracture toughness is 26.9MPa^1/2。

Example 4

s1, adding Mo, FeB, Fe, Cr, Ni, C and LaB with the purity of not less than 99.5%₆Mixing the powder, wherein the mixing mass ratio is as follows: 44.4 percent of Mo; 29.7 percent of FeB; 19.375% of Fe and 2.5% of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:0.75%。

d. 1230-750 ℃ C: the average cooling speed is4 ℃/min respectively;

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The obtained cermet has the properties of: the hardness is 89.5HRA, the bending strength is 1705.06MPa, and the fracture toughness is 24.4MPa^1/2。

Example 5

s1, adding Mo, FeB, Fe, Cr, Ni, C and LaB with the purity of not less than 99.5%₆Mixing the powder, wherein the mixing mass ratio is as follows: 44.4 percent of Mo; 29.7 percent of FeB; 19.125% of Fe and 2.5% of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:1.00%。

d. 1230-750 ℃ C: the average cooling speed is4 ℃/min respectively;

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The properties of the obtained metal ceramic are as follows: the hardness is 89.5HRA, the bending strength is 1691.93MPa, and the fracture toughness is 20.5MPa^1/2. Example 6

d. 1230-750 ℃ C: the average cooling speed is 8 ℃/min respectively;

e.750 ℃ -room temperature: the average cooling speed is respectively 6.5 ℃/min to obtain Mo₂FeB₂A base cermet.

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The properties of the obtained metal ceramic are as follows: the hardness is 90.0HRA, the bending strength is 1893.26MPa, and the fracture toughness is 27.6MPa^1/2。

Example 7

Boride modified Mo₂FeB₂The base cermet is prepared through mixing the raw materials, ball millingThe preparation method comprises the following steps of drying, forming and vacuum sintering:

d. 1230-750 ℃ C: the average cooling speed is 12 ℃/min respectively;

e.750 ℃ -room temperature: the average cooling speed is respectively 8.5 ℃/min to obtain Mo₂FeB₂A base cermet.

Mo in the invention₂FeB₂The preparation method of the base metal ceramic is simple and has low cost. The properties of the obtained metal ceramic are as follows: the hardness is 90.3HRA, the bending strength is 1867.26MPa, and the fracture toughness is 24.8MPa^1/2。

For Mo prepared in examples 1 to 7₂FeB₂Relative density and mechanical properties of the base cermets, measured according to the international standard (ISO/BIS 4505), the results of which are shown in table 1:

TABLE 1

The above is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification made on the basis of the technical scheme according to the technical idea provided by the invention falls within the protection scope of the claims of the invention.

Claims

1. Boride modified Mo₂FeB₂The base cermet is characterized in that: mo₂FeB₂The base cermet consists of Mo, FeB, Fe, Cr, Ni, C and LaB₆The powder material is prepared through mixing, ball milling, drying, pressing to form and vacuum sintering, and is mainly prepared with Mo₂FeB₂Hard phase and Fe-based binder phase.

2. The boride-modified Mo of claim 1₂FeB₂The base cermet is characterized in that Mo, FeB, Fe, Cr, Ni, C and LaB₆The mass ratio of the powder is respectively as follows: 44.4 percent of Mo; 29.7 percent of FeB; 19.125-20.125% of Fe and 2.5% of Cr; 2.9 percent of Ni; 0.375 percent of C; LaB₆:0.1~1.0%。

3. The boride-modified Mo of claim 2₂FeB₂The base cermet is characterized in that LaB₆The mass ratio of the components is respectively as follows: 0.25%, 0.5%, 0.75%, or 1.0%.

4. Boride modified Mo₂FeB₂The preparation method of the base cermet is characterized by comprising the following steps:

(1) mixing Mo, FeB, Fe, Cr, Ni, C and LaB₆Weighing according to the mass ratio to obtain mixed powder, and carrying out ball milling by taking absolute ethyl alcohol as a ball milling medium;

(2) placing the slurry subjected to ball milling in the step (1) into a vacuum drying oven for drying, wherein the temperature of the vacuum drying oven is 80 ℃, and the drying time is 2 hours;

(3) pressing and forming the dried powder obtained in the step (2), wherein the forming pressure is 200MPa, and the pressure maintaining time is45 s;

(4) and (4) putting the pressed and formed green body in the step (3) into a vacuum sintering furnace for sintering.

5. The boride-modified Mo of claim 4₂FeB₂The preparation method of the base cermet is characterized by comprising the following steps: mo, FeB, Fe, Cr, Ni, C and LaB in step (1)₆The purity of the powder is more than 99.5 percent.

6. The boride-modified Mo of claim 4₂FeB₂The preparation method of the base cermet is characterized by comprising the following steps: the mass ratio of the mixed powder to the absolute ethyl alcohol in the step (1) is as follows: m is_Powder：m_EthanolThe rotation speed is 200-.

7. The boride-modified Mo of claim 4₂FeB₂The preparation method of the base cermet is characterized by comprising the following steps: the vacuum sintering stage in the step (4) is divided into the following stages:

8. The boride-modified Mo of claim 7₂FeB₂Preparation method of base cermetThe method is characterized in that: each sintering stage is under a vacuum degree of 10^-1Sintering under the pressure of-100 Pa.