CN106946567B - A kind of preparation method of iron-aluminum intermetallic compound and ZrO2 composite phase material mobile phone ceramic backplane - Google Patents

Abstract

The invention discloses a method for preparing a mobile phone ceramic back plate of an iron-aluminum intermetallic compound and ZrO ₂ composite material. The method comprises blending and grinding Fe ₃ Al intermetallic compound and ZrO ₂ , granulating and sintering to obtain the composite phase material. The composite material combines the excellent fracture toughness of Fe ₃ Al intermetallic compound with the good flexural strength and high hardness of ZrO ₂ due to the similar linear expansion coefficient of the two. In addition, the excess metal can be used as a sintering aid to make it work under normal pressure. It can be _densified in the sintering furnace, and the sintering aid fills the microscopic defects such as holes and cracks in the composite material to optimize the mechanical properties. The toughening effect reduces the problem of residual stress release and cracking during the cooling process of the multiphase material, improves the yield of sintered ceramics, and at the same time reduces the amount of zirconia used in the multiphase material and reduces the overall cost of the ceramic backplane.

Description

Preparation of a kind of Fe-Al intermetallic compound and ZrO2 composite material mobile phone ceramic backplane method

technical field

The invention relates to the field of preparation of structural ceramics, in particular to a method for preparing a mobile phone ceramic back plate made of an iron _- aluminum intermetallic compound and ZrO2 composite material.

Background technique

In recent years, with the rapid development of consumer electronics such as mobile phones, structural parts such as mobile phone backplanes have made remarkable progress. Especially driven by the design requirements of consumer electronic backplanes in the future 5G era, traditional metal casings and plastic casings are difficult to meet consumer demand, so new materials and preparation processes are urgently needed.

Because ZrO ₂ ceramics have high toughness, good hardness, and high wear resistance, they are widely used in the fields of structural ceramics and functional ceramics. It has also been reported that partially stabilized zirconia (TZP) can be used to prepare corrosion-resistant watch cases, watch parts and other instrument parts by powder metallurgy. Therefore, in recent years, more and more researchers have tried to apply it to mobile phone casings. For example, in the patent application number 201510309285.1, additives such as alumina and titanium oxide are added to the main phase of zirconia to prepare the mobile phone casing by casting. Another example is the patent application number 201510940002.3, which uses yttrium-stabilized zirconia ceramic powder and organic matter to mix and extrude the mobile phone casing. It is reported that the book "Structural Ceramics" written by Xie Zhipeng introduced that the fracture toughness of ZrO ₂ ceramics with the best toughening performance in commercial use is only 8-12MPa.m ^1/2 . Compared with the current metal shell and other structural parts, it is still low, resulting in the following problems: 1) The degree of drop resistance is still not good; 2) The yield rate of high-speed machining is low, and the cost of low-speed machining is high. In addition, yttrium partially stabilized zirconia has a phase change aging phenomenon, and repeated bumps and drastic temperature changes during use may lead to failure of structural parts. At the same time, the high cost of raw materials for the preparation of yttrium partially stabilized zirconia ceramics is also a problem that limits its large-scale application. . The present invention utilizes the iron _- aluminum compound and ZrO2 to basically have the same linear expansion coefficient in each temperature section, and develops a composite material of metal and ceramics, which effectively improves the fracture toughness and drop resistance of ceramic products.

Contents of the invention

In view of this, the present invention aims at the shortcomings of the prior art, and its main purpose is to provide a method for preparing a ceramic backplane of a mobile phone made of Fe-Al intermetallic compound and ZrO ₂ composite phase material, which method is to combine Fe ₃ Al intermetallic compound with Composite materials were obtained by granulating and sintering ZrO ₂ after blending and grinding. The composite material combines the excellent fracture toughness of the Fe ₃ Al intermetallic compound with the good flexural strength and high hardness of ZrO ₂ , and the prepared composite material has excellent comprehensive mechanical properties. In addition, in the material design process, the single metal deviates from the Fe ₃ Al molar ratio, and the excess metal can be used as a sintering aid to reduce the densification conditions of the composite material, so that it can be densified in an atmospheric sintering furnace, and the sintering aid can Fill the microscopic defects such as holes and cracks in the composite material, and further improve the mechanical properties of the composite material.

In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing a ceramic backboard of a mobile phone made of an iron-aluminum intermetallic compound and ZrO ₂ composite phase material, comprising the following steps:

a) Mole percentage Fe: Al=(71-77): (23-29) Weigh iron powder and aluminum powder to smelt the alloy, and spray under high pressure in an inert atmosphere to prepare iron-aluminum intermetallic compound powder;

b) weighing the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder obtained in step a) into a grinding jar according to the weight ratio (60-90): (10-40), using alcohol or water as the grinding medium, Grinding for 18h-24h to obtain mixed grinding powder;

c) high-energy ball milling the mixed grinding powder obtained in step b) for 3h to 5h;

d) granulating the mixed grinding powder treated in step c) to obtain granulated powder;

e) subjecting the granulated powder obtained in step d) to cold isostatic pressing under a pressure of 200MPa to 250MPa after dry pressing to obtain a cold isostatic pressed green body;

f) Processing and shaping the cold isostatic pressed green body by a numerical control machine tool in step e) to obtain a mobile phone ceramic back plate green body;

g) Sintering and cooling the mobile phone ceramic back plate green body obtained in step e) under vacuum or an inert atmosphere.

Preferably, Fe:Al=(71-75):(25-29) in step a).

Preferably, Fe:Al=(74-75):(25-26) in step a).

Preferably, the inert gas in step a) is Ar gas, and the pressure is 0.3MPa-0.5MPa.

Preferably, the weight percentage of the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder in step b) is (70-90): (10-30).

Preferably, the weight percentage of the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder in step b) is (85-90): (10-15).

Preferably, step d) is spray granulation.

Preferably, the degree of vacuum in step g) is -0.095MPa˜-0.099MPa, and the inert atmosphere is Ar gas.

Preferably, the sintering temperature in step g) is 1400° C. to 1600° C., and the heat preservation and sintering time is 2 h to 5 h.

Preferably, the cooling process in step g) is that the cooling rate is no higher than 1 °C/min above 1200 °C, the cooling rate is no lower than 50 °C/min between 1200 °C and 800 °C, and the temperature is cooled below 800 °C.

The beneficial effect of the present invention is to provide a method for preparing the ceramic backboard of a mobile phone made of iron _- aluminum intermetallic _compound and ZrO ₂ composite material. phase material. The composite material combines the excellent fracture toughness of the Fe ₃ Al intermetallic compound with the good flexural strength and high hardness of ZrO ₂ , and the prepared composite material has excellent comprehensive mechanical properties. In addition, the single component of the material design is excessive, and the excess component can be used as a sintering aid to reduce the densification condition of the composite material, so that it can be densified in the normal pressure sintering furnace, and the sintering aid can fill the composite phase material Micro-defects such as holes and cracks optimize the mechanical properties. The staged cooling process not only saves the ZrO2 high _- temperature phase in the composite material to room temperature, improves its toughening effect, but also reduces the release of residual stress during the cooling process of the composite material. The problem of cracking improves the yield rate of the product. At the same time, the amount of zirconia used in the composite material is reduced, and the cost is reduced.

Description of drawings

Figure 1 is a schematic diagram of the steps of the preparation method.

Detailed ways

The present invention is described in further detail below: a method for preparing a ceramic backboard of a mobile phone made of an iron-aluminum intermetallic compound and ZrO ₂ composite phase material, comprising the following steps:

a) Mole percentage Fe: Al=(71-77): (23-29) Weigh iron powder and aluminum powder to smelt the alloy, and spray under high pressure in an inert atmosphere to prepare iron-aluminum intermetallic compound powder;

b) weighing the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder obtained in step a) into a grinding jar according to the weight ratio (60-90): (10-40), using alcohol or water as the grinding medium, Grinding for 18-24 hours to obtain mixed grinding powder;

c) high-energy ball milling the mixed grinding powder obtained in step b) for 3h to 5h;

d) granulating the mixed grinding powder treated in step c) to obtain granulated powder;

e) subjecting the granulated powder obtained in step d) to cold isostatic pressing under a pressure of 200MPa to 250MPa after dry pressing to obtain a cold isostatic pressed green body;

f) Processing and shaping the cold isostatic pressed green body obtained in step e) by a numerical control machine tool to obtain a mobile phone ceramic back plate green body;

g) Sintering and cooling the mobile phone ceramic back plate green body obtained in step e) under vacuum or an inert atmosphere.

In this embodiment, Fe:Al=(71-75):(25-29) in step a).

In this embodiment, Fe:Al=(74-75):(25-26) in step a).

In this embodiment, the inert gas in step a) is Ar gas, and the pressure is 0.3-0.5 MPa.

In this embodiment, the weight percentage of the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder in step b) is (70-90): (10-30).

In this embodiment, the weight percentage of the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder in step b) is (85-90): (10-15).

In this embodiment, step d) is spray granulation.

In this embodiment, the degree of vacuum in step g) is -0.095MPa˜-0.099MPa, and the inert atmosphere is Ar gas.

In this embodiment, the sintering temperature in step g) is 1400° C. to 1600° C., and the heat preservation and sintering time is 2 h to 5 h.

In this embodiment, the cooling process in step g) is that the cooling rate is not higher than 1 °C/min above 1200 °C, the cooling rate is not lower than 50 °C/min between 1200 °C and 800 °C, and the cooling is carried out with the furnace below 800 °C.

The following are embodiments of the invention:

Example 1:

Calculated on the basis of 10kg of alloy ingredients, weigh iron powder and aluminum powder according to the molar percentage Fe:Al=71:29 and add them to the vacuum melting furnace, heat up to 1300°C for 2 hours to obtain iron-aluminum metal liquid, and drain it to an air pressure of 0.3MPa Ar gas atmosphere spraying prilling tower cooling powder to obtain iron-aluminum intermetallic compound powder.

Calculated on the basis of 3kg of alloy ingredients, weigh yttria-stabilized zirconia powder and iron-aluminum intermetallic compound powder into the grinding tank at a weight ratio of 60:40, use alcohol as the grinding medium, and grind for 24 hours to obtain a mixed grinding powder. The mixed and ground powder was high-energy ball milled again for 3 hours, then dried and ground by manual addition of paraffin wax binder, and closed spray granulation with nitrogen protection to obtain granulated powder. Put the granulation powder into the mold and dry press it to demould, and then use the cold isostatic pressing equipment to keep the pressure at 200MPa for 3 to 5 minutes, then release the pressure to obtain the cold isostatic pressed green body, and process and shape the green body with a CNC machine tool to obtain Mobile phone ceramic back plate green body.

Put the green body into a vacuum sintering furnace, set the vacuum degree to -0.095MPa, heat up to 1400°C for 5 hours and then cool down after sintering. Before cooling down to 1200°C, the cooling rate is 1°C/min. The cooling section adopts the rapid cooling process of filling with Ar gas, the cooling rate is 50°C/min, and the furnace cools below 800°C.

In order to test the mechanical properties of the mobile phone shell (back plate) ceramics, a number of samples tested by the three-point bending method and the single-side notched beam method were prepared according to the same process for mechanical performance testing. The test results show that the bending strength of the composite material is 840MPa , the fracture toughness is 31.7MPa.m ^1/2 . The fracture toughness is obviously better than commercial zirconia toughened ceramics, and the bending strength is equivalent to it. It solves the technical problem of poor fracture toughness of the mobile phone shell of the existing zirconia toughened ceramics, and is suitable for the development of mobile phones. and other structural needs.

Example 2:

Calculated on the basis of 15kg of alloy ingredients, weigh iron powder and aluminum powder according to the molar percentage Fe:Al=77:23 and add them to the vacuum melting furnace, heat up to 1350°C for 1.5 hours to obtain iron-aluminum metal liquid, and drain it to a pressure of 0.5 The Ar gas atmosphere of MPa is sprayed in a prilling tower to cool and make powder to obtain iron-aluminum intermetallic compound powder.

Calculated on the basis of a 30kg alloy batching, the magnesia-stabilized zirconia powder and the iron-aluminum intermetallic compound powder are weighed into the grinding tank at a weight ratio of 90:10, and water is used as the grinding medium to grind for 18 hours to obtain a mixed grinding powder. The mixed milled powder was high-energy ball milled again for 5 hours, and then a polyvinyl alcohol binder was added to spray and granulate to obtain granulated powder. Put the granulation powder into the mold and then dry press it to demould, and then use the cold isostatic pressing equipment to keep the pressure under the pressure of 250MPa for 3 to 5 minutes, and then release the pressure to obtain the cold isostatic pressed green body, which is machined and shaped by the CNC machine tool to obtain Mobile phone ceramic back plate green body.

Put the green body into a vacuum sintering furnace, set the vacuum degree to -0.099MPa, raise the temperature to 1550°C for 2 hours and then cool down after sintering. Before cooling down to 1200°C, the cooling rate is 0.8°C/min. The cooling section adopts the rapid cooling process of filling with Ar gas, the cooling rate is 60°C/min, and it is cooled with the furnace below 800°C.

In order to test the mechanical properties of the mobile phone shell (back plate) ceramics, a number of samples tested by the three-point bending method and the single-side notched beam method were prepared according to the same process for mechanical performance testing. The test results show that the bending strength of the composite material is 950MPa , the fracture toughness is 18.1MPa.m ^1/2 . The fracture toughness is obviously better than commercial zirconia toughened ceramics, and the bending strength is equivalent to it. It solves the technical problem of poor fracture toughness of the mobile phone shell of the existing zirconia toughened ceramics, and is suitable for the development of mobile phones. and other structural needs.

Example 3:

Calculated on the basis of 15kg of alloy ingredients, weigh iron powder and aluminum powder according to the molar percentage Fe:Al=75:25 and add them to the vacuum melting furnace, heat up to 1300°C for 2 hours to obtain iron-aluminum metal liquid, and drain it to an air pressure of 0.5MPa Ar gas atmosphere spraying prilling tower cooling powder to obtain iron-aluminum intermetallic compound powder.

Calculated on the basis of a 30kg alloy batching, the magnesia-stabilized zirconia powder and the iron-aluminum intermetallic compound powder are weighed into the grinding tank at a weight ratio of 70:30, and alcohol is used as the grinding medium to grind for 20 hours to obtain a mixed grinding powder. The mixed milled powder was high-energy ball milled again for 4 hours, and then a paraffin wax binder was added to spray granulate to obtain granulated powder. Add the granulation powder into the mold and dry press it to demould, and then use the cold isostatic pressing equipment to keep the pressure under the pressure of 220MPa for 3 to 5 minutes, and then release the pressure to obtain the cold isostatic pressed green body. Mobile phone ceramic back plate green body.

Put the green body into an Ar gas atmosphere sintering furnace, raise the temperature to 1600°C for 2 hours and then cool down after sintering. Before cooling down to 1200°C, the cooling rate is 0.8°C/min. In the cold process, the cooling rate is 60°C/min, and the furnace cools below 800°C.

In order to test the mechanical properties of the mobile phone shell (back plate) ceramics, a number of samples tested by the three-point bending method and the single-side notched beam method were prepared according to the same process to test the mechanical properties. The test results show that the bending strength of the composite material is 980MPa , the fracture toughness is 25.5MPa.m ^1/2 . The fracture toughness is obviously better than commercial zirconia toughened ceramics, and the bending strength is equivalent to it. It solves the technical problem of poor fracture toughness of the mobile phone shell of the existing zirconia toughened ceramics, and is suitable for the development of mobile phones. and other structural needs.

Example 4:

Calculated on the basis of 15kg of alloy ingredients, weigh iron powder and aluminum powder according to the molar percentage Fe:Al=74:26 and add them to the vacuum melting furnace, heat up to 1300°C for 2 hours to obtain iron-aluminum metal liquid, and drain it to an air pressure of 0.4MPa Ar gas atmosphere spraying prilling tower cooling powder to obtain iron-aluminum intermetallic compound powder.

Calculated on the basis of a 25kg alloy batching, the magnesia-stabilized zirconia powder and the iron-aluminum intermetallic compound powder are weighed into the grinding tank at a weight ratio of 85:15, and water is used as the grinding medium to grind for 20 hours to obtain a mixed grinding powder. The mixed milled powder was high-energy ball milled again for 4 hours, and then a polyvinyl alcohol binder was added to spray granulate to obtain granulated powder. Add the granulation powder into the mold and dry-press it, then demould, and then use the cold isostatic pressing equipment to keep the pressure under the pressure of 220MPa for 3 to 5 minutes, and then release the pressure to obtain the cold isostatic pressed green body, which is machined and shaped to obtain Mobile phone ceramic back plate green body.

Put the green body into a vacuum sintering furnace, raise the temperature to 1550°C for 3 hours and then cool down after sintering. Before cooling down to 1200°C, the cooling rate is 0.8°C/min. In the cold process, the cooling rate is 60°C/min, and the furnace cools below 800°C.

In order to test the mechanical properties of the mobile phone shell (back plate) ceramics, a number of samples tested by the three-point bending method and the single-side notched beam method were prepared according to the same process for mechanical performance testing. The test results show that the bending strength of the composite material is 910MPa , the fracture toughness is 19.9MPa.m1/2. The fracture toughness is obviously better than commercial zirconia toughened ceramics, and the bending strength is equivalent to it. It solves the technical problem of poor fracture toughness of the mobile phone shell of the existing zirconia toughened ceramics, and is suitable for the development of mobile phones. and other structural parts.

Example 5:

Calculated on the basis of 15kg of alloy ingredients, weigh the iron powder and aluminum powder according to the molar percentage Fe:Al=74.5:25.5, add them to the vacuum melting furnace, heat up to 1300°C for 2 hours to obtain iron-aluminum metal liquid, and drain it to a pressure of 0.4MPa Ar gas atmosphere spraying prilling tower cooling powder to obtain iron-aluminum intermetallic compound powder.

Calculated on the basis of a 25kg alloy batching, the magnesia-stabilized zirconia powder and the iron-aluminum intermetallic compound powder are weighed into the grinding tank at a weight ratio of 87:13, and water is used as the grinding medium to grind for 20 hours to obtain a mixed grinding powder. The mixed milled powder was high-energy ball milled again for 4 hours, and then a polyvinyl alcohol binder was added to spray granulate to obtain granulated powder. Add the granulation powder into the mold and dry-press it, then demould, and then use the cold isostatic pressing equipment to keep the pressure under the pressure of 220MPa for 3 to 5 minutes, and then release the pressure to obtain the cold isostatic pressed green body, which is machined and shaped to obtain Mobile phone ceramic back plate green body.

Put the green body into a vacuum sintering furnace, raise the temperature to 1550°C for 3 hours and then cool down after sintering. Before cooling down to 1200°C, the cooling rate is 0.8°C/min. In the cold process, the cooling rate is 60°C/min, and the furnace cools below 800°C.

In order to test the mechanical properties of the mobile phone shell (back plate) ceramics, a number of samples tested by the three-point bending method and the single-side notched beam method were prepared according to the same process for mechanical performance testing. The test results show that the bending strength of the composite material is 960MPa , Fracture toughness is 19.5MPa.m1/2. The fracture toughness is obviously better than commercial zirconia toughened ceramics, and the bending strength is equivalent to it. It solves the technical problem of poor fracture toughness of the mobile phone shell of the existing zirconia toughened ceramics, and is suitable for the development of mobile phones. and other structural parts.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. a kind of iron _- aluminum intermetallic compound and ZrO Composite material mobile phone ceramic back plate preparation method, it is characterized in that comprising the following steps: a) Mole percentage Fe: Al=(74.5~77): (23~25.5) Weigh iron powder and aluminum powder to smelt the alloy, and spray under high pressure in an inert atmosphere to prepare a non-stoichiometric Fe ₃ Al iron-aluminum intermetallic Compound powder, in which excess metal participates in sintering as a sintering aid; b) weighing the yttrium-stabilized zirconia powder and the iron-aluminum intermetallic compound powder obtained in step a) into a grinding tank according to the weight ratio (87-90): (10-13), using alcohol or water as the grinding medium, Grinding for 18h-24h to obtain mixed grinding powder; c) high-energy ball milling the mixed grinding powder obtained in step b) for 3h to 5h; d) granulating the mixed grinding powder treated in step c) to obtain granulated powder; e) Dry pressing the granulated powder obtained in step d) and then performing cold isostatic pressing under a pressure of 200MPa to 250MPa to obtain a cold isostatic pressed green body; f) Processing and shaping the cold isostatic pressed green body by a numerical control machine tool in step e) to obtain a mobile phone ceramic back plate green body; g) Sintering and cooling the mobile phone ceramic back plate green body obtained in step e) under vacuum or an inert atmosphere. 2. the preparation method of the mobile phone ceramic back plate of iron-aluminum intermetallic compound and ZrO composite phase material according to claim ₁ , is characterized in that: the Fe in step a): Al=74.5:25.5. 3. the preparation method of the mobile phone ceramic backboard of iron-aluminum intermetallic compound and ZrO ₂ composite phase material according to claim 2, it is characterized in that: step a) in Fe:Al=77:23. 4. The preparation method of the mobile phone ceramic backplane made of iron-aluminum intermetallic compound and ZrO2 composite material according to claim ₃ , characterized in that: in step a), the inert gas is _N2 , and the pressure is 0.3MPa～0.5MPa . 5. iron-aluminum intermetallic compound according to claim 4 and ZrO _The preparation method of the mobile phone ceramic backboard of composite phase material, it is characterized in that: step b) in the yttrium-stabilized zirconia powder and iron-aluminum intermetallic compound powder The weight percentage is 87:13. 6. iron-aluminum intermetallic compound according to claim 5 and ZrO _The preparation method of the mobile phone ceramic backboard of composite phase material, it is characterized in that: step b) in the yttrium-stabilized zirconia powder and iron-aluminum intermetallic compound powder The weight percentage is 90:10. 7. The method for preparing a mobile phone ceramic backplane made of iron-aluminum intermetallic compound and ZrO ₂ composite phase material according to claim 6, characterized in that: step d) is spray granulation. 8. The method for preparing a mobile phone ceramic backplane made of iron-aluminum intermetallic _compound and ZrO composite phase material according to claim 7, characterized in that: the degree of vacuum in step g) is -0.095MPa～-0.099MPa, and the inert atmosphere for argon gas. 9. The preparation method of the mobile phone ceramic backboard of iron-aluminum intermetallic _compound and ZrO composite phase material according to claim 8, it is characterized in that: in step g), the sintering temperature is 1400 DEG C ~ 1600 DEG C, and the heat preservation and sintering time is 2h～5h. 10. The preparation method of the mobile phone ceramic backplane made of iron _- aluminum intermetallic compound and ZrO2 composite material according to claim 9, characterized in that: step g) cooling process is that the cooling rate is not higher than 1°C above 1200°C /min, the cooling rate is not lower than 50°C/min at 1200°C~800°C, and cools with the furnace below 800°C.