CN108821767B

CN108821767B - Preparation method of composite zirconia ceramic backboard

Info

Publication number: CN108821767B
Application number: CN201810635869.1A
Authority: CN
Inventors: 贾建平; 周晖雨
Original assignee: Suzhou Shanren Nano Technology Co ltd
Current assignee: SUZHOU SHANREN NANO TECHNOLOGY Co.,Ltd.
Priority date: 2018-06-20
Filing date: 2018-06-20
Publication date: 2022-01-18
Anticipated expiration: 2038-06-20
Also published as: CN108821767A

Abstract

The invention discloses a preparation method of a composite zirconia ceramic backboard, which comprises the steps of pouring composite zirconia granulation powder into a backboard die for dry pressing and molding, and preparing a backboard sintered body by degreasing, high-temperature roasting and flash-firing the obtained model. The preparation method of the composite zirconia ceramic backboard related by the patent combines hot-pressing sintering and flash-firing technologies, the high-temperature roasting temperature is 500-700 ℃ lower than that of the hot-pressing sintering technology, and the total time of the high-temperature roasting is not more than two minutes, the obtained backboard sintering body not only has equivalent mechanical property with the product obtained by the hot-pressing sintering technology, but also has the characteristics of compact structure and no microscopic cavity defect; in addition, the method also has the advantages of simple and controllable process, high preparation efficiency and energy conservation, and is suitable for industrial production.

Description

Preparation method of composite zirconia ceramic backboard

Technical Field

The invention belongs to the technical field of ceramic back plates, and particularly relates to a preparation method of a composite zirconia ceramic back plate.

Background

With the development of communication technology and mobile phone technology, the 5G and wireless charging era is coming, but the requirements of the two on the material of the mobile phone back plate are high, and the shielding effect on electromagnetic signals needs to be as small as possible, so that the non-metal back plate material will become the inevitable choice for future mobile phones.

The composite zirconia ceramic has good performances such as hardness, breaking strength, toughness and thermal conductivity, and has obvious advantages compared with non-metallic materials such as plastic and glass back plates; in addition, the composite zirconia ceramics has the characteristics of beauty and skin friendliness, so that the composite zirconia ceramics is expected to be applied to high-end mobile phone products. The manufacturing and processing flow of the composite zirconia ceramic back plate can be divided into four links of material proportioning, molding, sintering and finish machining; the sintering process generally adopts a high-temperature sintering technology, the time consumption is long, the energy consumption is high, the control of the product quality is difficult, and the yield of the obtained product is low, so that the cost of the existing ceramic back plate is high, the capacity is limited, especially the three-dimensional mobile phone back plate has higher machining difficulty due to the complex design shape, and if the machining allowance can be reduced in the sintering process, the near-net forming is realized, and the production cost of the mobile phone back plate can be greatly reduced. Therefore, the rapid and efficient sintering process of the composite zirconia ceramic three-dimensional mobile phone backboard is the key point for accelerating the application of the backboard.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method of the composite zirconia ceramic back plate, which not only improves the production efficiency and performance of the composite zirconia ceramic back plate, but also reduces the production cost.

In order to achieve the purpose, the technical scheme of the invention is as follows: a preparation method of a composite zirconia ceramic backboard comprises the following steps:

(1) pouring the composite zirconia granulation powder into a back plate mold for dry pressing molding;

(2) placing the model obtained in the step (1) in air for degreasing to obtain a biscuit;

(3) placing the biscuit obtained in the step (2) in air for roasting;

(4) and (3) placing electrodes on two sides of the biscuit obtained in the step (3), applying direct current, linearly increasing the voltage until a flash phenomenon occurs, then keeping the current constant, sintering for a certain time, and cooling to room temperature to obtain the back plate sintered body.

Preferably, the backboard is a three-dimensional mobile phone backboard.

Preferably, the composite zirconia granulated powder in the step (1) consists of the following components: 3-12 mol% of yttrium oxide, 22-88 mol% of zirconium oxide and 0-66 mol% of aluminum oxide.

Preferably, the pressure for dry pressing in the step (1) is 200-250MPa, and the dwell time is 20-40 s.

Preferably, the degreasing temperature of the mold in the step (2) is 400-.

Preferably, the roasting temperature of the biscuit in the step (3) is 900-1000 ℃, and the roasting time is 30-60 s.

Preferably, the electrode in the step (4) is a platinum electrode.

Preferably, the voltage increase rate in the step (4) is 20 to 100V/s.

Preferably, the constant current in the step (4) is 800-1000A.

Preferably, the sintering time at a constant current in the step (4) is 20 to 50 s.

Preferably, the voltage at which the flash phenomenon occurs in the step (4) is 60 to 100V.

The invention has the beneficial effects that:the invention relates to a preparation method of a composite zirconia ceramic backboard, which combines hot-pressing sintering and flash-firing technologies, wherein the high-temperature sintering temperature is 500-700 ℃ lower than that of the hot-pressing sintering technology, the total time of the high-temperature sintering is not more than two minutes, the obtained backboard sintered body not only has equivalent mechanical property to the product obtained by the hot-pressing sintering technology, but also has the characteristics of compact structure and no microscopic cavity defect, the density can reach more than 99.5 percent of theoretical density, the bending strength is higher than 850MPa, and the fracture toughness exceeds 7 MPa.m^1/2And an average grain size of less than 1 micron; in addition, the method also has the advantages of simple and controllable process, high preparation efficiency and energy conservation, and is suitable for industrial production.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments will be briefly introduced below.

FIG. 1 is an SEM photograph of a sintered body of a backing plate obtained by the first preparation example;

FIG. 2 is an SEM photograph of a sintered body of a back plate obtained in example II;

FIG. 3 is an SEM photograph of a sintered body of a back plate obtained by the third preparation example;

FIG. 4 is an SEM photograph of a sintered body of a back plate obtained by the fourth preparation example.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the following will make clear and complete descriptions of the technical solutions in the present application with reference to the embodiments.

Example one

A preparation method of a composite zirconia ceramic backboard comprises the following steps:

(1) pouring the composite zirconia granulation powder into a three-dimensional mobile phone backboard mould, and keeping the pressure at 200Mpa for 30s to perform dry pressing and molding, wherein the components of the composite zirconia granulation powder are shown in Table 1;

(2) degreasing the model obtained in the step (1) in the air at 470 ℃ for 2.0h to obtain a biscuit;

(3) placing the biscuit obtained in the step (2) in air and roasting at 930 ℃ for 50 s;

(4) and (3) placing platinum electrodes on two sides of the biscuit obtained in the step (3), introducing direct current, linearly increasing the voltage at the speed of 60V/s until a flash phenomenon occurs, keeping the current constant at 950A for 20s, and cooling to room temperature to obtain the back plate sintered body.

The obtained sintered body of the back plate was characterized by a field emission electron microscope (SEM), and the result is shown in fig. 1, from which it can be seen that the sintered body of the back plate prepared in this example has a compact structure, no micro-hole defects, uniform grain size, and an average grain size of less than 1 μm.

Example two

(1) pouring the composite zirconia granulation powder into a three-dimensional mobile phone backboard mould, and keeping the pressure for 20s at 220Mpa to dry-press the composite zirconia granulation powder, wherein the components of the composite zirconia granulation powder are shown in Table 1;

(2) degreasing the model obtained in the step (1) in air at 400 ℃ for 2.5h to obtain a biscuit;

(3) placing the biscuit obtained in the step (2) in air and roasting for 40s at 1000 ℃;

(4) and (3) placing platinum electrodes on two sides of the biscuit obtained in the step (3), applying direct current, linearly increasing the voltage at the speed of 20V/s until a flash phenomenon occurs, keeping the current constant at 1000A for 30s, and cooling to room temperature to obtain the back plate sintered body.

The obtained sintered body of the back plate was characterized by a field emission electron microscope (SEM), and the result is shown in fig. 2, which shows that the sintered body of the back plate prepared in this example has a compact structure, no micro-hole defects, uniform grain size, and an average grain size of less than 1 μm.

EXAMPLE III

(1) pouring the composite zirconia granulation powder into a three-dimensional mobile phone backboard mould, and keeping the pressure at 230Mpa for 40s to perform dry pressing and molding, wherein the components of the composite zirconia granulation powder are shown in Table 1;

(2) degreasing the model obtained in the step (1) in air at 500 ℃ for 3.0h to obtain a biscuit;

(3) placing the biscuit obtained in the step (2) in air and roasting for 30s at 900 ℃;

(4) and (3) placing platinum electrodes on two sides of the biscuit obtained in the step (3), applying direct current, linearly increasing the voltage at the speed of 100V/s until a flash phenomenon occurs, keeping the current at 800A for 40s, and cooling to room temperature to obtain the back plate sintered body.

The obtained sintered body of the back plate was characterized by a field emission electron microscope (SEM), and the result is shown in fig. 3, which shows that the sintered body of the back plate prepared in this example has a compact structure, no micro-hole defects, uniform grain size, and an average grain size of less than 1 μm.

Example four

(1) pouring the composite zirconia granulation powder into a three-dimensional mobile phone backboard mould, and keeping the pressure at 250Mpa for 35s to perform dry pressing and molding, wherein the components of the composite zirconia granulation powder are shown in Table 1;

(2) degreasing the model obtained in the step (1) in air at 450 ℃ for 4.0h to obtain a biscuit;

(3) placing the biscuit obtained in the step (2) in air and roasting at 970 ℃ for 60 s;

(4) and (3) placing platinum electrodes on two sides of the biscuit obtained in the step (3), applying direct current, linearly increasing the voltage at the speed of 80V/s until a flash phenomenon occurs, keeping the current at 900A for 50s, and cooling to room temperature to obtain the back plate sintered body.

The obtained sintered body of the back plate was characterized by a field emission electron microscope (SEM), and the result is shown in fig. 4, from which it can be seen that the sintered body of the back plate prepared in this example has a compact structure, no micro-hole defects, uniform grain size, and an average grain size of less than 1 μm.

TABLE 1

Comparative example 1

The back plate sintered body is prepared by adopting the raw material ratio of the first embodiment and adopting the traditional hot-pressing sintering technology.

The sintered bodies of the back plates prepared in examples one to four and comparative example one were subjected to density, bending strength, fracture toughness and mechanical property tests, and the test results are shown in table 2.

Wherein, the density testing method is an Archimedes method, and the testing temperature is as follows: 25 ℃; the bending strength adopts a bending strength tester, and the testing method is a three-point bending method; the testing method of fracture toughness is an indentation method;

TABLE 2

As can be seen from Table 2, the mechanical properties of the back plate sintered body doped with alumina are obviously improved, and the back plate sintered body with a compact structure can be obtained by the method of the invention, and the density of the back plate sintered body can reach the theoretical density (6.11 g/cm)³) 99.5% or more, bending strength higher than 850MPa, fracture toughness over 7 MPa.m^1/2(ii) a In addition, as can be seen from the comparison of the first example and the first comparative example, the mechanical properties of the product obtained by the method of the present invention are equivalent to those of the product obtained by the hot-pressing sintering technology, but the temperature for high-temperature roasting is low, the time is short, and therefore, the preparation cost is low, and the production process is simple, green and controllable.

The above-described embodiments are merely preferred embodiments of the present invention, and are not intended to limit the present invention. It should be noted that, for a person skilled in the art, many variations and modifications can be made without departing from the spirit of the invention, which falls within the scope of the invention.

Claims

1. The preparation method of the composite zirconia ceramic backboard is characterized by comprising the following steps:

(1) pouring the composite zirconia granulation powder into a back plate mold for dry pressing molding, wherein the pressure of the dry pressing molding is 200-250MPa, the pressure maintaining time is 20-40s, and the composite zirconia granulation powder comprises the following components: 6-12 mol% of yttrium oxide, 22-66 mol% of zirconium oxide and 25-66 mol% of aluminum oxide;

(2) placing the model obtained in the step (1) in air for degreasing to obtain a biscuit, wherein the degreasing temperature is 400-;

(3) placing the biscuit obtained in the step (2) in air for roasting, wherein the roasting temperature of the biscuit is 900 ℃, and the roasting time is 30 s;

(4) and (3) placing electrodes on two sides of the biscuit obtained in the step (3), applying direct current, linearly increasing the voltage until the flash phenomenon occurs, keeping the voltage at 60-100V when the flash phenomenon occurs, keeping the current constant, sintering for a certain time, keeping the constant current at 800-1000A, keeping the sintering time at the constant current at 20-50s, and cooling to room temperature to obtain the backboard sintered body.

2. The method for preparing a composite zirconia ceramic backplate according to claim 1, wherein the backplate is a three-dimensional mobile phone backplate.

3. The method for preparing a composite zirconia ceramic backplate according to claim 1, wherein the electrode in step (4) is a platinum electrode.

4. The method for preparing a composite zirconia ceramic backplate according to claim 1, wherein the voltage increase rate in the step (4) is 20 to 100V/s.