CN119571167A - A nano-precipitated phase-reinforced binder gradient hard composite material and preparation method thereof - Google Patents

Abstract

The present application belongs to the field of materials science and engineering technology, and in particular, relates to a nano-precipitation phase reinforced binder gradient hard composite material and a preparation method thereof. The present application provides a nano-precipitation phase reinforced binder gradient hard composite material, comprising: AlN powder, WC powder, metal binder and carbide. The present application also provides a preparation method for the above composite material. In the present application, a gradient cemented carbide with surface hard phase enrichment, high core binder content and gradient distribution at the micrometer scale is prepared through the innovative design of raw materials and preparation methods; a nano-scale precipitation phase gradient distribution can also be formed in the binder through different sintering temperatures; the gradient distribution of the hard phase-binder at the micrometer scale and the gradient distribution of the ordered γ' precipitation phase in the binder at the nanometer scale are coupled and synergistically strengthened to achieve an improvement in the comprehensive performance of the product.

Description

Nanometer precipitated phase reinforced adhesive gradient hard composite material and preparation method thereof

Technical Field

The application belongs to the technical field of material science and engineering, and particularly relates to a nano precipitated phase reinforced adhesive gradient hard composite material and a preparation method thereof.

Background

The hard alloy has the excellent characteristics of high hardness, high strength, high wear resistance, high corrosion resistance, low thermal expansion coefficient, high chemical stability and the like, is known as industrial teeth, and is widely used in the fields of cutting processing, geological exploration, mining, petroleum drilling, die manufacturing and the like. The hard alloy material mainly comprises WC as a hard phase and Co as a binder, wherein the WC endows the alloy with excellent wear resistance and bearing capacity, and the Co enhances the impact resistance of the alloy.

The traditional Co-based binder has insufficient performance, is difficult to meet the severe requirements of severe working conditions such as oxidation, corrosion and high temperature on the performance, and limits the industrial application range of the hard alloy. In addition, the hard phase mainly comprising WC and the binder mainly comprising Co have large differences in properties such as thermal expansion coefficient, elastic modulus, poisson's ratio and the like, so that the hard alloy still has the problem that the overall hardness and toughness are difficult to coordinate in the service process.

Therefore, a nano precipitated phase reinforced binder gradient hard composite material and a preparation method thereof are developed, which are used for solving the technical defects that hard alloy is difficult to meet the performance requirement of severe working conditions and the hardness and toughness are difficult to coordinate in the prior art, and become the problems to be solved urgently by the technicians in the field.

Disclosure of Invention

Based on the above, it is necessary to provide a nano precipitated phase reinforced binder gradient hard composite material and a preparation method thereof, aiming at the technical defects that hard alloy is difficult to meet the performance requirement of severe working conditions and the hardness and toughness are difficult to coordinate in the prior art.

The application provides a nano precipitated phase reinforced binder gradient hard composite material, which comprises AlN powder, WC powder and a metal binder, wherein the metal binder comprises Co and/or Ni;

In the metal binder, the feeding amount of Co element is 15-30wt% of the composite material, and the feeding amount of Ni element is 15-30wt% of the composite material.

In one embodiment, in the metal binder, the feeding amount of Co element is 20-25wt% of the composite material, and the feeding amount of Ni element is 20-25wt% of the composite material.

In one embodiment, the composition further comprises a carbide comprising TaC and/or NbC.

In one embodiment, the amount of the transition metal element in the carbide is 2-8wt% of the composite material.

In one embodiment, the amount of the transition metal element in the carbide is 4-6wt% of the composite material.

In one embodiment, the aluminum element in the AlN powder is added in an amount of 2-6wt% of the composite material in percentage by mass.

In one embodiment, the aluminum element in the AlN powder is added in an amount of 3-5wt% of the composite material in percentage by mass.

The application also provides a preparation method of the composite material, which comprises the steps of:

step one, raw material mixing, namely mixing all raw materials to obtain a first product;

ball milling and drying, namely, ball milling and drying the first product to obtain a second product;

step three, dry pressing, namely compacting the second product to obtain a third product:

sintering the third product under vacuum condition to obtain the product.

In one embodiment, in the fourth step, the sintering is subjected to denitrification pretreatment.

In one embodiment, the denitrification pretreatment method comprises the steps of heating the third product to 1200-1250 ℃ at a heating rate of 5-10 ℃ per minute, and maintaining the temperature for 60-120 min.

In one embodiment, the sintering method is to raise the temperature to 1300-1400 ℃ at a temperature raising speed of 2-5 ℃ per minute, and keep the temperature for 30-120 min.

In summary, the nano precipitated phase reinforced binder gradient hard composite material provided by the application comprises the following raw materials of AlN powder, WC powder, a metal binder and carbide, wherein the feeding amount of aluminum element in the AlN powder is 2-6wt% of the composite material by mass percent. The application also provides a preparation method of the composite material, which comprises the steps of raw material mixing, ball milling and drying, dry pressing and sintering. According to the technical scheme, the gradient hard composite material with the enriched surface hard phases, the high core binder content and the gradient distribution in the micrometer scale is prepared through the innovative design of the raw materials and the preparation method, the gradient distribution of the precipitation phases in the nanometer scale can be formed in the binder through different sintering temperatures, and the product comprehensive performance is improved through mutual coupling and cooperative reinforcement of the gradient distribution of the hard phases in the micrometer scale and the gradient distribution of ordered gamma' precipitation phases in the nanometer scale, so that the technical defects that in the prior art, hard alloy is difficult to meet the requirements of severe working condition performance and hardness and toughness are difficult to coordinate are effectively overcome.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 shows the elemental contents of Al and W on the surface and core of a WC-25Co-25Ni-3Al sample in the technical scheme provided by the embodiment of the application;

FIG. 2 shows BSE images of (a) WC-25Co-25Ni-3Al, (b) WC-25Co-25Ni-3Al-8Ta, and (c) WC-25Co-25Ni-3Al-8Nb samples, showing the gradient region of the samples from the surface to the core, in the technical scheme provided by the embodiment of the application;

FIG. 3 is an SEM image of WC-25Co-25Ni-3Al sample binder, wherein (a) and (b) are near surface binders and (c) and (d) are core binders, according to an embodiment of the present application;

FIG. 4 is a plot of the macroscopic Vickers hardness HV0.2 of (a) WC-25Co-25Ni-3Al, (b) WC-25Co-25Ni-3Al-8Ta, and (c) WC-25Co-25Ni-3Al-8Nb samples from surface to core in the solution provided by the example of the present application;

FIG. 5 is a graph showing the micro Vickers hardness HV0.01 of a binder from surface to core of a sample sintered at 1350 ℃ (a) WC-25Co-25Ni-3Al, (b) WC-25Co-25Ni-3Al-8Ta, and (C) WC-25Co-25Ni-3Al-8Nb, WC-25Co-25Ni, according to the embodiment of the present application;

FIG. 6 is a graph showing the micro Vickers hardness HV0.01 of a sample of (a) WC-25Co-25Ni-3Al, (b) WC-25Co-25Ni-3Al-8Ta, and (C) WC-25Co-25Ni-3Al-8Nb sintered at 1320 ℃ from the surface to the core binder in the technical scheme provided by the embodiment of the application;

Fig. 7 is a schematic flow chart of a method for preparing a nano precipitated phase reinforced binder gradient hard composite material in the technical scheme provided by the embodiment of the application.

Detailed Description

The embodiment of the application provides a nano precipitated phase reinforced binder gradient hard composite material and a preparation method thereof, which are used for solving the technical defects that hard alloy is difficult to meet the performance requirement of severe working conditions and hardness and toughness are difficult to coordinate in the prior art.

In order that the above objects, features and advantages of the application will be readily understood, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.

In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present application, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed, mechanically connected, electrically connected, directly connected, indirectly connected through an intervening medium, or in communication between two elements or in an interaction relationship between two elements, unless otherwise explicitly specified. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present application, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

In the following, referring to fig. 7, the preparation of the gradient hard composite material is performed according to the nano precipitated phase reinforced binder gradient hard composite material and the preparation method thereof provided by the application.

Example 1

This example is a specific example of the preparation of a gradient hard composite product 1.

Step one, mixing raw materials

Mixing WC, co, ni, alN according to the following mass percentage, and mixing to obtain a first product 1;

WC:45.44%;Co:25%;Ni:25%;AlN:4.56%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 1 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 1 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 1 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 1.

Step four, sintering

And placing the third product 1 in a graphite crucible, and sintering in vacuum to obtain the product 1.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

The vacuum sintering method is that the temperature is raised from 1230 ℃ to 1350 ℃ at a temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 1 with the gamma' -nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface binder of the product 1 reaches 4.61GPa and the hardness HV0.01 of the core binder reaches 5.99GPa.

As shown in fig. 5 (a), the product 1 has a distribution of microhardness HV0.01 of the adhesive from the surface to the core, and as can be seen from fig. 5, the adhesive hardness near the surface of the product 1 is low, and the adhesive hardness gradually increases with increasing depth from the surface.

Furthermore, the binder hardness of product 1 is very significantly improved compared to pure WC-Co-Ni cemented carbide without gamma prime precipitation strengthening binder.

Example 2

This example is a specific example of the preparation of a gradient hard composite product 2.

Step one, mixing raw materials

Mixing WC, co, ni, alN, taC according to the following mass percentage, and mixing to obtain a first product 2;

WC:36.91%;Co:25%;Ni:25%;AlN:4.56%;TaC:8.53%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN, taC powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 2 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the mixture is dried for 8 hours in an oven at 80 ℃ to obtain the second product 2.

Step three, dry pressing

And placing the second product 2 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 2.

Step four, sintering

And placing the third product 2 in a graphite crucible, and sintering in vacuum to obtain the product 2.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

The vacuum sintering method is that the temperature is raised from 1230 ℃ to 1350 ℃ at a temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 2 with the gamma' -nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface binder of the product 2 reaches 5.08GPa and the hardness HV0.01 of the core binder reaches 6.06Gpa.

As shown in fig. 5 (b), the distribution of the microhardness HV0.01 of the adhesive of the product 2 from the surface to the core is shown, and as can be seen from fig. 5, the adhesive hardness of the near-surface and the core of the product 2 does not exhibit a distinct gradient distribution of hardness as that of the product 1, but is improved to some extent with respect to the adhesive hardness of the near-surface of the product 1. In addition, the binder hardness of product 2 is very significantly improved compared to pure WC-Co-Ni cemented carbide without gamma prime precipitation strengthening binder.

Example 3

This example is a specific example of the preparation of a gradient hard composite product 3.

Step one, mixing raw materials

Mixing WC, co, ni, alN, nbC according to the following mass percentage, and mixing to obtain a first product 3;

WC:36.41%;Co:25%;Ni:25%;AlN:4.56%;NbC:9.03%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN, nbC powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 3 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 3 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 3 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 3.

Step four, sintering

And placing the third product 3 in a graphite crucible, and sintering in vacuum to obtain the product 3.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

The vacuum sintering method is that the temperature is raised from 1230 ℃ to 1350 ℃ at a temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 3 with the gamma' -nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the binder on the surface layer of a sample of the product 3 reaches 5.72GPa and the hardness HV0.01 of the binder on the core reaches 6.02GPa.

The distribution of the microhardness HV0.01 of the adhesive of the product 3 from the surface to the core is shown in fig. 5 (c), and the adhesive hardness of the near surface and the core of the product 3 does not exhibit a significant gradient distribution of hardness as in the product 1, but is improved to some extent with respect to the adhesive hardness of the near surface of the product 1. In addition, the binder hardness of product 3 is very significantly improved compared to pure WC-Co-Ni cemented carbide without gamma prime precipitation strengthening binder.

Example 4

This example is a specific example of the preparation of a gradient hard composite product 4.

Step one, mixing raw materials

WC, co, ni, alN is proportioned according to the following mass percentage;

WC:45.44%;Co:25%;Ni:25%;AlN:4.56%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 4 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 4 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 4 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 4.

Step four, sintering

And placing the third product 4 in a graphite crucible, and sintering in vacuum to obtain the product 4.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

the vacuum sintering method is that the temperature is raised from 1230 ℃ to 1320 ℃ at the temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 4 with the gamma' -nano precipitated phase reinforced adhesive is obtained after vacuum sintering, and the hardness HV0.01 of the surface adhesive of the product 4 reaches 5.64GPa and the hardness HV0.01 of the core adhesive reaches 6.12GP.

The distribution of the microhardness HV0.01 of the binder of the product 4 from the surface to the core is shown in fig. 6 (a), and the binder hardness of the near-surface and core of the product 4 does not exhibit a significant gradient of hardness, but the binder hardness of the product 4 is very significantly improved compared to a pure WC-Co-Ni cemented carbide without a gamma prime precipitation phase strengthening binder.

Example 5

This example is a specific example of the preparation of a gradient hard composite product 5.

Step one, mixing raw materials

Mixing WC, co, ni, alN, taC according to the following mass percentage, and mixing to obtain a first product 5;

WC:36.91%;Co:25%;Ni:25%;AlN:4.56%;TaC:8.53%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN, taC powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 5 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 5 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 5 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 5.

Step four, sintering

And placing the third product 5 in a graphite crucible, and sintering in vacuum to obtain the product 5.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

the vacuum sintering method is that the temperature is raised from 1230 ℃ to 1320 ℃ at the temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 5 with the gamma' -nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface layer binder of the product 5 reaches 5.27GPa and the hardness HV0.01 of the core binder reaches 5.92GPa.

The product 5 has a distribution of microhardness HV0.01 of the binder from the surface to the core as shown in fig. 6 (b), and the product 5 has a lower binder hardness near the surface and a relatively higher binder hardness at the core. In addition, the binder hardness of product 5 is very significantly improved compared to pure WC-Co-Ni cemented carbide without gamma prime precipitation strengthening binder.

Example 6

This example is a specific example of the preparation of a gradient hard composite product 6.

Step one, mixing raw materials

Mixing WC, co, ni, alN, nbC according to the following mass percentage, and mixing to obtain a first product 6;

WC:36.41%;Co:25%;Ni:25%;AlN:4.56%;NbC:9.03%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN, nbC powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 6 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 6 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 6 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 6.

Step four, sintering

And placing the third product 6 in a graphite crucible, and sintering in vacuum to obtain the product 6.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

the vacuum sintering method is that the temperature is raised from 1230 ℃ to 1320 ℃ at the temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 6 with the gamma' -nano precipitated phase reinforced adhesive is obtained after vacuum sintering, and the hardness HV0.01 of the surface adhesive of the product 6 reaches 5.56GPa and the hardness HV0.01 of the core adhesive reaches 5.65GPa.

The product 6 has a distribution of microhardness HV0.01 of the binder from the surface to the core as shown in fig. 6 (c), with the binder hardness being lower near the surface of the product 6 and the binder hardness being relatively higher at the core. In addition, the binder hardness of product 6 is very significantly improved compared to pure WC-Co-Ni cemented carbide without gamma prime precipitation strengthening binder.

Example 7

This example is a specific example of the preparation of a gradient hard composite product 7.

Step one, mixing raw materials

Mixing WC, co, ni, alN according to the following mass percentage, and mixing to obtain a first product 7;

WC:50.44%;Co:15%;Ni:30%;AlN:4.56%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 7 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 7 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 7 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 7.

Step four, sintering

And placing the third product 7 in a graphite crucible, and performing vacuum sintering to obtain the product 7.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

The vacuum sintering method is that the temperature is raised from 1230 ℃ to 1350 ℃ at a temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 7 with the gamma-nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface binder of the product 7 reaches 4.90GPa and the hardness HV0.01 of the core binder reaches 5.79Gpa, and the experimental result shows that the hardness of the binder near the surface of the product 7 is slightly lower than that of the core binder, and in addition, compared with the pure WC-Co-Ni hard alloy without the gamma-nano precipitated phase reinforced binder, the hardness of the binder of the product 7 is remarkably improved.

Example 8

This example is a specific example of the preparation of a gradient hard composite product 8.

Step one, mixing raw materials

Mixing WC, co, ni, alN according to the following mass percentage, and mixing to obtain a first product 8;

WC:50.44%;Co:30%;Ni:15%;AlN:4.56%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 8 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 8 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 8 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 8.

Step four, sintering

And placing the third product 8 in a graphite crucible, and sintering in vacuum to obtain the product 8.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

The vacuum sintering method is that the temperature is raised from 1230 ℃ to 1350 ℃ at a temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 8 with the gamma-nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface binder of the product 8 reaches 5.08GPa and the hardness HV0.01 of the core binder reaches 5.63Gpa, and the experimental result shows that the hardness of the binder near the surface of the product 8 is slightly lower than that of the core binder, and in addition, compared with the pure WC-Co-Ni hard alloy without the gamma-nano precipitated phase reinforced binder, the hardness of the binder of the product 8 is remarkably improved.

Example 9

This example is a specific example of the preparation of a gradient hard composite product 9.

Step one, mixing raw materials

Mixing WC, co, ni, alN according to the following mass percentage, and mixing to obtain a first product 9;

WC:50.44%;Co:15%;Ni:30%;AlN:4.56%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 9 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 9 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 9 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 9.

Step four, sintering

And placing the third product 9 in a graphite crucible, and performing vacuum sintering to obtain the product 9.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

the vacuum sintering method is that the temperature is raised from 1230 ℃ to 1320 ℃ at the temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 9 with the gamma-nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface binder of the product 9 reaches 5.14GPa and the hardness HV0.01 of the core binder reaches 5.69Gpa, and the experimental result shows that the hardness of the binder near the surface of the product 9 is slightly lower than that of the core binder, and in addition, compared with the pure WC-Co-Ni hard alloy without the gamma-nano precipitated phase reinforced binder, the hardness of the binder of the product 9 is remarkably improved.

Example 10

This example is a specific example of the preparation of a gradient hard composite product 10.

Step one, mixing raw materials

Mixing WC, co, ni, alN according to the following mass percentage, and mixing to obtain a first product 10;

WC:50.44%;Co:30%;Ni:15%;AlN:4.56%;

wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co, ni, alN powder is more than or equal to 99.9%, and the granularity is 1-3 mu m.

Step two, ball milling and drying

The first product 10 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball-material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the second product 10 is obtained after drying for 8 hours in an oven at 80 ℃.

Step three, dry pressing

And placing the second product 10 in a die, pressurizing at 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third product 10.

Step four, sintering

And placing the third product 10 in a graphite crucible, and performing vacuum sintering to obtain the product 10.

The specific process conditions are as follows:

The denitrification pretreatment method comprises the steps of heating to 1230 ℃ at a heating rate of 5-10 ℃ per min, and preserving heat for 120min at the temperature;

the vacuum sintering method is that the temperature is raised from 1230 ℃ to 1320 ℃ at the temperature rising speed of 2 ℃ per minute, the temperature is kept for 60 minutes, and the vacuum degree is always kept to be less than or equal to 10Pa in the sintering process.

In the embodiment, the gradient hard composite material product 10 with the gamma-nano precipitated phase reinforced binder is obtained after vacuum sintering, and the hardness HV0.01 of the surface binder of the product 10 reaches 4.93GPa and the hardness HV0.01 of the core binder reaches 5.57Gpa, and the experimental result shows that the hardness of the binder near the surface of the product 10 is slightly lower than that of the core binder, besides, compared with the pure WC-Co-Ni hard alloy without the gamma-nano precipitated phase reinforced binder, the hardness of the binder of the product 10 is remarkably improved.

Comparative example

This comparative example is a specific example for preparing a control, in which AlN and MC (m=ta, nb) were not added to the raw materials.

Step one, mixing raw materials

Proportioning WC, co and Ni according to the following mass percentage to obtain a first reference substance 1;

WC:50%;Co:25%;Ni:25%;

Wherein the purity of WC powder is more than or equal to 99.9%, the granularity is 3-5 mu m, the purity of Co powder is more than or equal to 99.9%, and the granularity is 1-3 mu m;

Step two, ball milling and drying

The first control 1 is put into a ball mill, ball milling is carried out for 6 hours under the conditions that the ball material ratio is 5:1 and absolute ethyl alcohol is used as a grinding medium and the rotating speed is 200r/min until the powder is fully and uniformly mixed, and then the mixture is dried for 8 hours in an oven at 80 ℃ to obtain the second control 1.

Step three, dry pressing

And (3) placing the second comparison object 1 in a die, pressurizing for 150MPa, maintaining the pressure for 5-10 min, and demolding to prepare a pressed blank to obtain a third comparison object 1.

Step four, sintering

And placing the third control object 1 in a graphite crucible, and adopting vacuum sintering, wherein the sintering process conditions are that the heating speed is 5-10 ℃ per minute, the sintering temperature is 1350 ℃, the sintering heat preservation time is 120 minutes, and the sintering vacuum degree is less than or equal to 5Pa.

The average HV0.01 of the control obtained by vacuum sintering was 3.28Gpa, and the adhesive hardness HV0.01 of the sample was used as the comparison data of FIGS. 5 and 6.

According to the technical scheme and the embodiment, the nano precipitated phase reinforced adhesive gradient hard composite material and the preparation method thereof provided by the application have the following advantages:

Firstly, the nano precipitated phase reinforced adhesive gradient hard composite material prepared by adopting the technical scheme provided by the application has a gradient structure composed of WC, alN and a composite adhesive, and the gradient structure sequentially comprises that the surface hard phase is enriched, alN is not contained, the content of the core adhesive is higher, the hard phase-adhesive has gradient distribution on the micrometer scale, the advantages of higher surface hardness and good core toughness are realized, and the good combination of the hardness and the toughness of the hard composite material is realized.

In the preparation method provided by the application, heat preservation treatment is carried out in the denitrification stage, alN close to the surface is decomposed first, nitrogen is released outwards, and along with the denitrification process, an N element distribution gradient with rich core part and poor surface is formed. Due to the effect of the N element on the activity of the W element in the binder, at this stage the W element has a tendency to migrate from the N-rich core to the N-lean surface, eventually the W element forms a gradient distribution of elements with a core lean in W and a surface rich in W.

In the cooling stage of the sintering process, more WC grains are separated out due to the enrichment of W element in the binder near the surface, so that a gradient structure with enriched surface hard phases and higher core binder content is formed.

Further, in order to verify the analysis results, samples having the compositions WC-25Co-25Ni-3Al, WC-25Co-25Ni-3Al-8Ta, WC-25Co-25Ni-3Al-8Nb were vacuum sintered according to the denitrification process parameters (120 min at 1230 ℃) and the sintering process parameters (60 min at 1320 ℃).

After the sintered product is inlaid and polished, the content of each element in the binder of the WC-25Co-25Ni-3Al sample near the surface and the core is detected by using a Scanning Electron Microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), wherein the content of Al and W elements is shown in figure 1. The back scattered electron image (BSE) of the three component sample is shown in fig. 2.

It can be derived from fig. 1 and fig. 2 that, after the treatment of the preparation method provided by the application, gradient distribution of elements is formed in the sample, gradient distribution of Al and W elements are mutually coupled, and finally, a gradient structure of the surface hard phase as shown in fig. 2, which is enriched and has no AlN and higher content of core binder, and the hard phase-binder is in micrometer scale, is formed.

Secondly, the nano precipitated phase reinforced adhesive gradient hard composite material prepared by adopting the technical scheme provided by the application has the gamma '-nano precipitated phase with an L1 ₂ structure in the adhesive, wherein the gamma' -nano precipitated phase is a hard and brittle phase, is precipitated in a gamma matrix phase and is in a coherent relation with the matrix phase, so that the hardness of the adhesive can be obviously improved on the premise of keeping the toughness of the matrix phase, and the mechanical property of the adhesive is comprehensively improved.

In the preparation method provided by the application, heat preservation treatment is carried out in the denitrification stage, alN close to the surface is decomposed first, part of Al is dissolved in the binder in a solid manner, and along with the denitrification process, an N element distribution gradient with rich core part and poor surface N is formed. Because of the influence of N element on the activities of Al and W elements in the binder, the Al element in the binder forms an element distribution gradient with rich core and poor surface with the progress of dissolution and precipitation, and the W element forms an element distribution gradient with poor core and rich surface with W during the heating stage of the sintering process.

Wherein, al element is used as a forming element of gamma ' phase, which can increase the volume fraction of gamma ' phase in the binder and increase the quantity of gamma ' phase, and W element is used as a stabilizing element of gamma ' phase, which can increase the solid solution temperature and volume fraction of gamma ' phase. The binder near the surface has relatively low content of Al element, high content of W element, high solid solution temperature of gamma ' phase, long evolution temperature interval of gamma ' phase, high evolution degree, and large grain diameter of the final gamma ' phase in the whole cooling process, and relatively, the binder of the core has relatively high content of Al element, low content of W element, low solid solution temperature of gamma ' phase and small grain diameter of the final gamma ' phase.

Further, to verify the above analysis conclusion, the morphology of the binder was observed under SEM after cutting, inlaying, polishing, and etching the sample having the composition WC-25Co-25Ni-3Al, as shown in fig. 3.

As can be seen from fig. 3, the size of the precipitated phase in the near-surface binder is significantly larger than that of the core, and the gradient distribution of the particle size of the precipitated phase is formed in the binder because the N element gradient inside the product is formed by decomposition of AlN during the denitrification pretreatment in the sintering process, and the Al element gradient is formed by the Al element.

Thirdly, the nano precipitated phase reinforced adhesive gradient hard composite material prepared by the technical scheme provided by the application realizes gradient distribution in a hard phase, an adhesive layer, an adhesive internal matrix and a nano precipitated phase layer respectively, and the hard phase, the adhesive layer, the adhesive internal matrix and the nano precipitated phase layer are mutually coupled and cooperatively reinforced, so that the hardness and the toughness of the material are effectively improved.

Further, to verify the above conclusion, samples of the compositions WC-25Co-25Ni-3Al, WC-25Co-25Ni-3Al-8Ta, WC-25Co-25Ni-3Al-8Nb were vacuum sintered according to the denitrification process parameters (120 min at 1230 ℃) and the sintering process parameters (60 min at 1320 ℃).

The product obtained after sintering was subjected to a vickers hardness test with a load of 200gf from the surface to the core after inlay and polishing, and the test results are shown in fig. 4.

As can be seen from fig. 4, all samples exhibited a high surface macro hardness and a lower core macro hardness, consistent with the microscopic image results shown in fig. 2. The results show that the sample prepared by the preparation method provided by the application has the characteristics of enrichment of the surface hard phase, no AlN and gradient distribution of the hard phase-binder with higher core binder content in micrometer dimensions, has the advantages of higher surface hardness and good core toughness, and realizes good combination of hardness and toughness of the hard composite material.

Fourth, in the preparation method provided by the application, the operation is simple, the control of the thickness of the gradient layer can be realized by controlling the heat preservation time and the temperature rise and reduction speed in the denitrification stage, and in addition, the high vacuum degree is also beneficial to reducing the sintering temperature, so that the sintering preparation of the nano precipitated phase reinforced adhesive gradient hard composite material product is realized efficiently.

In summary, the nano precipitated phase reinforced binder gradient hard composite material provided by the application comprises the following raw materials of AlN powder, WC powder, a metal binder and carbide, wherein the feeding amount of aluminum element in the AlN powder is 2-6wt% of the composite material in percentage by mass. The application also provides a preparation method of the composite material, which comprises the steps of raw material mixing, ball milling and drying, dry pressing and sintering. According to the technical scheme, the gradient hard composite material with the enriched surface hard phases, the high core binder content and the gradient distribution in the micrometer scale is prepared through innovative design of raw materials and a preparation method, the gradient distribution of precipitation phases in the nanometer scale can be formed in the binder through different sintering temperatures, and the comprehensive performance of the product is improved through mutual coupling and synergistic reinforcement of the gradient distribution of the hard phases in the micrometer scale and the gradient distribution of ordered gamma' precipitation phases in the binder in the nanometer scale. Therefore, the technical defect that in the prior art, hard alloy is difficult to meet the performance requirement of severe working conditions and hard to coordinate the hardness and toughness is effectively overcome.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description. Also, other implementations may be derived from the above-described embodiments, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the claims. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (9)

1. The nano precipitated phase reinforced adhesive gradient hard composite material is characterized in that the raw materials of the composite material comprise AlN powder, WC powder and a metal adhesive, wherein the metal adhesive comprises Co and/or Ni;

In the metal binder, the feeding amount of Co element is 15-30wt% of the composite material, and the feeding amount of Ni element is 15-30wt% of the composite material.

2. The composite material according to claim 1, wherein the metal binder comprises 20-25wt% of the composite material and 20-25wt% of the composite material.

3. The composite material according to claim 1 or 2, wherein the composite material further comprises a carbide comprising TaC and/or NbC.

4. The composite material according to claim 3, wherein the amount of the transition metal element added to the carbide is 2-8 wt% of the composite material.

5. The composite material according to claim 1 or 2, wherein the amount of aluminum element in the AlN powder is 2 to 6wt% of the composite material in mass percent.

6. A method of producing a composite material according to any one of claims 1 to 5, comprising:

step one, raw material mixing, namely mixing all raw materials to obtain a first product;

ball milling and drying, namely, ball milling and drying the first product to obtain a second product;

step three, dry pressing, namely compacting the second product to obtain a third product:

sintering the third product under vacuum condition to obtain the product.

7. The method according to claim 6, wherein in the fourth step, the sintering is subjected to denitrification pretreatment.

8. The method according to claim 7, wherein the denitrification pretreatment is carried out by heating the third product to 1200-1250 ℃ at a heating rate of 5-10 ℃ per minute, and maintaining the temperature for 60-120 min.

9. The method according to any one of claims 6 to 8, wherein the sintering method is performed by heating to 1300 to 1400 ℃ at a heating rate of 2 to 5 ℃ per minute, and maintaining the temperature for 30 to 120 minutes.