阅读说明：本技术 一种陶瓷后盖及制备方法 (Ceramic rear cover and preparation method thereof ) 是由 周群飞 左友林 邱海浪 于 2020-09-09 设计创作，主要内容包括：本发明提供一种陶瓷后盖及制备方法,本发明的纹理陶瓷手机后盖采用流延工艺得到流延膜片,再将流延膜片叠层、真空包装后经温等静压成型得到具有纹理的陶瓷生坯,经脱脂烧结后得到纹理陶瓷毛坯,而且表面纹理图案及色彩稳定,不易变色,耐刮擦。本发明利用具有LOGO成型腔的成型模具制作LOGO,以实现纹理和LOGO的一次成型,且纹理面为阴文结构,LOGO面为阳文结构,纹理介质片的加入解决了脱模时生坯与模具粘连,造成LOGO处在脱模、抛光等过程产生的分层、脱落、缺角等缺陷,从而影响外观效果的问题。节约了模具的开发成本,缩短了新产品的开发周期,并有效提高加工效率。(The invention provides a ceramic rear cover and a preparation method thereof, the texture ceramic rear cover of a mobile phone obtains a casting membrane by adopting a casting process, then the casting membrane is laminated and vacuum-packed, and is subjected to warm isostatic pressing to obtain a ceramic green body with texture, and a texture ceramic blank is obtained after degreasing and sintering, and the texture ceramic blank has stable surface texture patterns and colors, is not easy to discolor and is scratch-resistant. According to the invention, the LOGO is manufactured by using the forming die with the LOGO forming cavity, so that the texture and the LOGO are formed at one time, the texture surface is of a negative structure, the LOGO surface is of a positive structure, and the addition of the texture medium sheet solves the problems that the LOGO is layered, falls off, unfilled corners and the like in the processes of demolding, polishing and the like due to the adhesion of a green body and the die during demolding, so that the appearance effect is influenced. The development cost of the die is saved, the development period of a new product is shortened, and the processing efficiency is effectively improved.)

1. A preparation method of a ceramic rear cover comprises the following steps:

A) mixing the raw materials to obtain mixed slurry;

the raw materials comprise zirconium oxide, an organic solvent, a dispersant, a binder and a plasticizer;

B) carrying out casting forming after vacuumizing and defoaming the mixed slurry to obtain a casting membrane;

C) sequentially placing the texture medium sheet and the casting film sheet into a mold with a LOGO molding cavity, and performing warm isostatic pressing to obtain a ceramic green body with 3D textures and LOGO patterns;

D) and sequentially carrying out glue discharging and sintering on the ceramic green body to obtain the ceramic rear cover with 3D textures and LOGO patterns.

2. The method according to claim 1, wherein the zirconia, the organic solvent and the dispersant are mixed, and the binder and the plasticizer are added to perform secondary mixing to obtain a mixed slurry.

3. The preparation method according to claim 1, characterized in that the mass fractions of the components in the mixed slurry are as follows:

zirconium oxide: 40-70%; organic solvent: 40-60%; dispersing agent: 0.4-3.0%; adhesive: 5-15%; plasticizer: 3-10%.

4. The method according to claim 1, wherein the viscosity of the mixed slurry after vacuum degassing is 2000 to 10000 cp.

5. The method of making of claim 1, wherein the depth of the LOGO in the mold is greater than the depth of the texture in the textured media sheet;

the mould is provided with a forming cavity, and the bottom edge of the forming cavity is provided with a chamfer.

6. The method as claimed in claim 1, wherein the texture media sheet is made of fiber cloth, nylon cloth, polyethylene or ABS plastic.

7. The method of making of claim 1, wherein said textured media sheet is provided with hollowed out areas corresponding to said LOGO pattern locations.

8. The method for preparing the silicon carbide ceramic according to claim 1, wherein the temperature of the warm isostatic pressing is 60-80 ℃; preheating for 5-10 min; the pressure maintaining pressure is 150-200 MPa; the pressure maintaining time is 10-25 min.

9. The preparation method according to claim 1, wherein the temperature of the binder removal is 500-800 ℃, and the heat preservation time of the binder removal is 1-2 hours;

the sintering temperature is 1350-1450 ℃, and the sintering heat preservation time is 1-2 hours.

10. The ceramic rear cover prepared by the preparation method according to any one of claims 1 to 9;

in the ceramic rear cover, the height of the LOGO pattern is greater than the depth of the 3D texture;

the mixed slurry comprises the following components in percentage by mass:

zirconium oxide: 40-70%; organic solvent: 40-60%; dispersing agent: 0.4-3.0%; adhesive: 5-15%; plasticizer: 3-10%.

Technical Field

The invention belongs to the technical field of ceramic materials, and particularly relates to a ceramic rear cover and a preparation method thereof.

Background

With the coming of the 5G era, the requirements of smart phones on signal transmission are higher and higher, the metal back plate has a greater signal shielding effect and becomes a key factor restricting the development of the smart phones, and therefore, the rear cover material of the smart phones must be changed from a metal material into a non-metal material such as glass, ceramic and the like. Compared with glass materials, the ceramic material has the characteristics of good appearance effect, good touch feeling like jade, high strength, high hardness, corrosion resistance, high chemical stability, scratch resistance, friction resistance, no signal shielding, excellent heat dissipation performance and the like, and is gradually an important choice for realizing differentiation in the electronic consumer industry. At present, the material for manufacturing the ceramic mobile phone rear cover is mainly zirconia, and the ceramic mobile phone rear cover has the problems of few color types and monotonous appearance style, and cannot meet the individual requirements of consumers and the pursuit of fashionable and beautiful appearance of the mobile phone.

The currently common surface decoration treatment scheme for the rear cover of the ceramic mobile phone mainly comprises two types: 1. and manufacturing patterns or textures on the surface of the ceramic rear cover by adopting processes such as thermal spraying, silk-screen printing or PVD (physical vapor deposition). 2. Regular grooves are carved on the surface of the ceramic rear cover by adopting a laser carving process, so that a texture effect is realized. The method processes the sintered ceramics, the zirconia ceramics are hard and compact, the processing difficulty is high, product defects are easily caused in the processing process, the yield is low, the coating decoration only has a plane effect, the three-dimensional effect is avoided, the wear and the color fading are easy, and the texture effect with good durability and rich patterns cannot be manufactured.

Based on the above problems, the prior art proposes a method for transferring a texture or a LOGO pattern to a ceramic cover plate by using a casting process and a forming mold with the texture or the LOGO pattern, but the texture is a negative structure, the LOGO pattern is a positive structure, and the texture and the LOGO are processed and manufactured simultaneously, so that a green body is adhered to the mold during demolding, and the LOGO has the defects of layering, falling, unfilled corners and the like generated in post-processing processes of demolding, polishing and the like, thereby affecting the appearance effect. In addition, special dies need to be developed when products with different texture effects are manufactured, and the die opening cost is high.

Disclosure of Invention

The invention aims to provide a ceramic rear cover and a preparation method thereof, the preparation method can obtain texture and LOGO patterns with three-dimensional sense on the surface through one-step forming, and solves the problems of layering, falling off, corner defect and the like caused by the fact that LOGO is in the processes of demoulding, polishing and the like due to adhesion of a green body and a mould during demoulding.

The invention provides a preparation method of a ceramic rear cover, which comprises the following steps:

A) mixing the raw materials to obtain mixed slurry;

the raw materials comprise zirconium oxide, an organic solvent, a dispersant, a binder and a plasticizer;

B) carrying out casting forming after vacuumizing and defoaming the mixed slurry to obtain a casting membrane;

C) sequentially placing the texture medium sheet and the casting film sheet into a mold with a LOGO molding cavity, and performing warm isostatic pressing to obtain a ceramic green body with 3D textures and LOGO patterns;

D) and sequentially carrying out glue discharging and sintering on the ceramic green body to obtain the ceramic rear cover with 3D textures and LOGO patterns.

Preferably, the zirconia, the organic solvent and the dispersant are mixed, and then the binder and the plasticizer are added to perform secondary mixing, so as to obtain the mixed slurry.

Preferably, the mass fractions of the components in the mixed slurry are as follows:

zirconium oxide: 40-70%; organic solvent: 40-60%; dispersing agent: 0.4-3.0%; adhesive: 5-15%; plasticizer: 3-10%.

Preferably, the viscosity of the mixed slurry after vacuum degassing is 2000-10000 cp.

Preferably, the depth of the LOGO in the mold is greater than the depth of the texture in the textured media sheet;

the mould is provided with a molding cavity, and the bottom edge of the molding cavity is provided with a chamfer.

Preferably, the texture medium sheet is made of fiber cloth, nylon cloth, polyethylene or ABS plastic.

Preferably, the texture medium sheet is provided with a hollow-out area corresponding to the position of the LOGO pattern.

Preferably, the temperature of the warm isostatic pressing is 60-80 ℃; preheating for 5-10 min; the pressure maintaining pressure is 150-200 MPa; the pressure maintaining time is 10-25 min.

Preferably, the temperature of the discharged rubber is 500-800 ℃, and the heat preservation time of the discharged rubber is 1-2 hours;

the sintering temperature is 1350-1450 ℃, and the sintering heat preservation time is 1-2 hours.

The ceramic rear cover prepared by the preparation method described above;

in the ceramic rear cover, the height of the LOGO pattern is greater than the depth of the 3D texture;

the mixed slurry comprises the following components in percentage by mass:

zirconium oxide: 40-70%; organic solvent: 40-60%; dispersing agent: 0.4-3.0%; adhesive: 5-15%; plasticizer: 3-10%.

The invention provides a preparation method of a ceramic rear cover, which comprises the following steps: A) mixing zirconium oxide, an organic solvent, a dispersant, an adhesive and a plasticizer to obtain mixed slurry; B) carrying out casting forming after vacuumizing and defoaming the mixed slurry to obtain a casting membrane; C) sequentially placing the texture medium sheet and the casting film sheet into a mold with a LOGO pattern, and carrying out warm isostatic pressing to obtain a ceramic green body; D) and sequentially carrying out glue discharging and sintering on the ceramic green body to obtain the ceramic rear cover.

The texture ceramic mobile phone rear cover provided by the invention adopts a casting process to obtain the casting membrane, then the casting membrane is laminated, vacuum-packed and subjected to warm isostatic pressing to obtain the ceramic green body with the texture, and the texture ceramic blank is obtained after degreasing and sintering.

According to the invention, the LOGO is manufactured by using the forming die with the LOGO forming cavity so as to realize one-step forming of textures and the LOGO, the texture surface is a concave surface (a negative structure), the LOGO surface is a convex surface (a positive structure), and the addition of the texture medium sheet solves the problems that the LOGO is layered, falls off, unfilled corners and the like in the processes of demolding, polishing and the like due to adhesion of a green body and the die during demolding, so that the appearance effect is influenced. In addition, when products with different texture effects are manufactured, a special mold does not need to be developed, only a medium with different surface texture patterns needs to be provided, and the textures on the medium are transferred to the surface of a green body through warm isostatic pressing, so that the development cost of the mold is saved, the development period of a new product is shortened, and the processing efficiency is effectively improved.

Drawings

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

FIG. 1 is a schematic diagram of the formation of a ceramic rear cover according to the present invention, wherein 1 is a casting film, 2 is a texture medium, and 3 is a mold with LOGO;

FIG. 2 is a mold with a LOGO in one embodiment of the present invention;

FIG. 3 is an SEM photograph of a casting film sheet in example 1 of the present invention;

FIG. 4 is an SEM image of a green body cross-section in example 1 of the present invention;

FIG. 5 is an SEM image of a cast membrane of comparative example 1 of the present invention;

FIG. 6 is a SEM cross-section of a green compact of comparative example 1 of the present invention.

Detailed Description

The invention provides a preparation method of a ceramic rear cover, which comprises the following steps:

A) mixing the raw materials to obtain mixed slurry;

the raw materials comprise zirconium oxide, an organic solvent, a dispersant, a binder and a plasticizer;

B) carrying out casting forming after vacuumizing and defoaming the mixed slurry to obtain a casting membrane;

C) sequentially placing the texture medium sheet and the casting film sheet into a mold with a LOGO molding cavity, and performing warm isostatic pressing to obtain a ceramic green body with 3D textures and LOGO patterns;

D) and sequentially carrying out glue discharging and sintering on the ceramic green body to obtain the ceramic rear cover.

In the invention, the raw materials include, but are not limited to, zirconia, an organic solvent, a dispersant, an adhesive and a plasticizer, and the zirconia, the organic solvent and the dispersant are preferably mixed for 2-24 hours, then the adhesive and the plasticizer are added, and the mixing is continued for 2-24 hours, so as to obtain a uniformly mixed slurry. By adopting a two-step mixing mode, the defects of low green density and low sintering density caused by insufficient grinding and dispersion of powder due to the fact that the binder and the powder are combined in advance can be effectively avoided.

In the present invention, the raw materials are preferably mixed in a ball mill tank by a method of grinding and dispersing, preferably by one of ball milling, stirring milling and sand milling, more preferably by sand milling.

According to the invention, zirconia powder is preferably used as a raw material, and the mass fraction of the zirconia powder is preferably 40-70%, more preferably 45-65%, and most preferably 50-60%; the organic solvent is preferably one or more of ethyl acetate, butyl acetate, ethanol, isopropanol, methyl ethyl ketone and toluene, and the mass fraction of the organic solvent is preferably 40-60%, more preferably 45-55%, and most preferably 50-55%; when the organic solvent is ethanol and ethyl acetate, the mass ratio of the ethanol to the ethyl acetate is 1: 1; the dispersant is preferably one or more of castor oil, phosphate ester and polyacrylate, the mass fraction of the dispersant is preferably 0.4-3.0%, more preferably 0.5-2.5%, most preferably 1.0-2.0%, and specifically, in the invention, the mass fraction of the dispersant may be 1.5%; the adhesive is preferably polyvinyl butyral, and the mass fraction of the adhesive is preferably 5-15%, more preferably 8-12%, and most preferably 10-11%; specifically, in the embodiment of the present invention, the amount of the plasticizer may be 7% or 5%, the plasticizer is preferably one or more of dibutyl phthalate, dioctyl phthalate and polyethylene glycol, the mass fraction of the plasticizer is preferably 3% to 10%, more preferably 5% to 8%, and in the embodiment of the present invention, the amount of the plasticizer may be 5% or 4%.

The invention uses proper addition of the adhesive and the plasticizer, has positive effect on improving the strength and the plasticity of the casting film, can effectively improve the capability of the casting film of generating deformation and not cracking under the action of pressure, and is beneficial to forming complete textures and LOGO patterns on the surface of the casting film.

After the mixed slurry is obtained, the mixed slurry is preferably subjected to vacuum defoaming, the defoaming is stopped when the viscosity of the slurry reaches a set value, and after the slurry is aged for a certain time, the height of a scraper of a casting machine is adjusted for casting to obtain the casting film.

The control of the viscosity of the slurry is very important to the influence of the quality of the casting membrane, the viscosity is too large, the fluidity of the slurry is poor, and the casting is not facilitated; too low viscosity can cause the slurry to be very sensitive to the change of casting and drying process parameters, easily cause defects and influence the density uniformity of the casting film.

In the present invention, the viscosity of the vacuum defoamed mixed slurry is preferably 2000 to 10000cp, more preferably 2000 to 5000cp, and most preferably 3000 to 4000cp, and specifically, in the embodiment of the present invention, the viscosity may be 3000cp or 4000 cp.

In the invention, the thickness of the casting membrane is preferably 0.1-0.5 mm.

After obtaining the casting film, the casting film is cut into required sizes according to the specification of a product, then a plurality of casting films are laminated to the required thickness, the texture medium sheet and the laminated casting film are sequentially placed into a mold with a LOGO forming cavity, wherein the texture medium sheet is in contact with the inner cavity of the forming mold and is positioned between the forming mold and the casting film, and finally the casting film is subjected to vacuum packaging and then placed in a warm isostatic press for static pressure forming to obtain a ceramic green body with 3D textures and LOGO patterns.

In the present invention, the texture medium sheet is preferably made of a fiber cloth, a nylon cloth, or a polymer film. For flat plates or 2.5D products, the texture medium has no special requirements, and for 3D products, the texture medium used in the invention has certain deformation capacity, can be tightly attached to the casting membrane during texture transfer and synchronously deforms. The texture medium sheet is also provided with a hollow area corresponding to the position of the LOGO pattern.

In the present invention, the material of the mold is not particularly limited, and may be an aluminum mold, a steel mold, or a graphite mold, and more preferably an aluminum mold.

In the invention, the mould can be designed into a 2D or 3D structure according to the requirements of products, and when the mould is designed into the 3D structure, the bottom edge of the forming cavity in the mould is preferably provided with a chamfer so as to prevent texture media from being damaged under the action of pressure, so that demoulding cannot be carried out, or water is caused when a vacuum package is broken and the product is scrapped.

In the invention, the texture depth of the medium and the logo depth of the mold are not larger than the thickness of the casting diaphragm, and the logo depth is larger than the texture depth, so that the texture surface is not damaged by grinding processing of the logo surface.

The temperature and pressure of the warm isostatic pressing have a large influence on the uniformity of green density and the interlayer lamination of the casting film. If the temperature and the pressure are too low, the lamination between the casting membrane layers is not tight enough after the temperature isostatic pressing, and the layering phenomenon is easy to occur. When the temperature is above the glass transition temperature of the plasticizer, further increases in temperature tend to cause overpressure cracking of the cast film. The temperature isostatic pressing parameters for manufacturing the texture cover plate are consistent with those of the smooth cover plate, and the process parameters are not required to be adjusted when the product type is changed.

In the invention, the temperature of the warm isostatic pressing is preferably 60-80 ℃, more preferably 65-75 ℃, and most preferably 70 ℃, specifically, in the embodiment of the invention, 70 ℃ or 80 ℃; according to the invention, the temperature of the warm isostatic pressing water is preferably slowly raised to the required temperature, namely a preheating process exists before the warm isostatic pressing, and the preheating time of the warm isostatic pressing is preferably 5-10 min, more preferably 6-9 min, and most preferably 7-8 min. The pressure of the warm isostatic pressing is preferably 150 to 200MPa, more preferably 160 to 180MPa, and in an embodiment of the present invention, the pressure may be 150MPa or 180 MPa. The dwell time of the warm isostatic pressing is preferably 10 to 25min, more preferably 15 to 20min, and specifically, in the embodiment of the present invention, may be 20 min.

According to the invention, the mold does not need to be manufactured again, and the texture medium sheet only needs to be replaced in the mold with the LOGO forming cavity. By warm isostatic pressing, the casting film is softened and pressed into the texture of the medium under certain temperature and pressure conditions. After cooling, the texture on the surface of the medium and the LOGO pattern on the surface of the die are transferred to the surface of the casting membrane, and a ceramic mobile phone rear cover green body with 3D presented texture and LOGO is obtained.

And sequentially carrying out glue discharging and sintering on the obtained green body to obtain the ceramic rear cover with the LOGO pattern with the 3D texture.

In the invention, the temperature of the binder removal is preferably 500-800 ℃, more preferably 550-750 ℃, and most preferably 600-700 ℃, specifically, in the embodiment of the invention, 550 ℃; the heat preservation time of the binder removal is preferably 1-2 hours. Preferably, the temperature rise procedure of the rubber discharge is as follows:

firstly, heating from normal temperature to 200 ℃ at the speed of 1-2 ℃/min, then heating from 200 ℃ to 500-800 ℃ at the speed of 0.3-1 ℃/min, and finally carrying out glue removal at the temperature of 500-800 ℃ to remove organic matter components in the blank.

In the invention, the sintering temperature is preferably 1350-1450 ℃, and more preferably 1400 ℃; the sintering time is preferably 1-2 hours.

After sintering is completed, the sintered product is preferably subjected to precise shape processing through CNC (computerized numerical control) so as to meet the size requirement of the finished product. Because the surface of the ceramic blank is a texture surface, only the inner cavity needs to be thinned, the machining allowance is greatly reduced, and the material cost and the machining cost are saved.

And finally, polishing treatment is carried out, so that the texture and LOGO on the surface of the glass are smoother, brighter and stronger in stereoscopic impression.

The invention provides a preparation method, which comprises the following steps: A) mixing zirconium oxide, an organic solvent, a dispersant, an adhesive and a plasticizer to obtain mixed slurry; B) carrying out casting forming after vacuumizing and defoaming the mixed slurry to obtain a casting membrane; C) sequentially placing the texture medium sheet and the casting film sheet into a mold with a LOGO pattern, and performing warm isostatic pressing to obtain a ceramic green body with 3D textures and the LOGO pattern; D) and sequentially carrying out glue discharging and sintering on the ceramic green body to obtain the ceramic rear cover with 3D textures and LOGO patterns.

The texture ceramic mobile phone rear cover provided by the invention adopts a casting process to obtain the casting membrane, then the casting membrane is laminated, vacuum-packed and subjected to warm isostatic pressing to obtain the ceramic green body with the texture, and the texture ceramic blank is obtained after degreasing and sintering.

According to the invention, the LOGO is manufactured by using the forming die with the LOGO forming cavity so as to realize one-step forming of textures and the LOGO, the texture surface is a concave surface (i.e. a negative structure), the LOGO surface is a convex surface (i.e. a positive structure), and the addition of the texture medium sheet solves the problem that the LOGO is influenced by the defects of layering, falling, unfilled corner and the like generated in the processes of demolding, polishing and the like due to adhesion of a green body and the die during demolding. In addition, when products with different texture effects are manufactured, a special mold does not need to be developed, only a medium with different surface texture patterns needs to be provided, and the textures on the medium are transferred to the surface of a green body through warm isostatic pressing, so that the development cost of the mold is saved, the development period of a new product is shortened, and the processing efficiency is effectively improved.

In order to further illustrate the present invention, the following detailed description is provided for the preparation method of a ceramic back cover in accordance with the present invention, but it should not be construed as limiting the scope of the present invention.