Brief introduction of zirconia ceramic mobile phone back sheet forming process
Time: 2018-12-29 Writer: mingrui
Brief introduction of zirconia ceramic mobile phone back sheet forming process
Ceramics have been widely used in our life due to their excellent characteristics. Among them, zirconia ceramics is expected to lead the future of smart products such as mobile phone backboards, smart watches and fingerprint recognition. Today, this article will briefly talk about the molding process of zirconia ceramic mobile phone back plate.
The molding from the raw material to the back of the mobile phone is roughly divided into the following stages: preparation of zirconia ceramic powder → processing and forming → discharge sintering → CNC grinding → grinding and polishing → laser / PVD → AF treatment.
1. Preparation of zirconia ceramic powder
Microcrystalline ceramics are a composite solid material obtained by heating glass crystallization to obtain a large amount of microcrystalline phase and a small amount of glass phase. Microcrystalline zirconium ceramics are abbreviated as microcrystalline zirconium, which has the properties of wear resistance, corrosion resistance, high strength and toughness.
The quality requirements for microcrystalline zirconium ceramic powder are as follows:
1. The particle size distribution is a normal distribution, and the classification accuracy is high;
2. The shape of the particles is close to a circle, the particle strength is high, and the stress is uniform;
3, the dispersion is better, no reunion or rarely reunion;
4, the purity should be as high as harmful impurities should be as low as possible.
Second, the zirconia ceramic powder processing:
At present, there are mainly four processing methods in the process:
1. Injection molding
Injection molding is carried out by adding a flow aid to the powder to fill the body of the desired shape. It mainly produces small precision ceramic parts with complex shapes, precise dimensions or with inserts.
2, compression molding
The molding is a powder which is granulated, has good fluidity, and is suitably granulated, and is loaded into the grinding tool, and an external force is applied through the plunger of the press to make the powder into a certain shape of the embryo body. The method is mainly used for producing ceramic products with high rigidity and flat shape, and has low cost, high material utilization rate, good shearability and recovery.
3, casting molding
The main steps of the casting process are as follows:
(1) firstly mixing the pulverized ceramic powder with an additive in a solvent to prepare a slurry having a certain viscosity;
(2) the slurry flows down from the container tube, and is scraped and coated on the special base tape by a scraper with a certain thickness;
(3) After drying and solidifying, the film which becomes the green germ strip is peeled off from the base tape.
(4) According to the size and shape of the finished product, it is necessary to process the raw embryo by punching, laminating, etc., and prepare the finished blank to be sintered.
The method is suitable for producing flaky ceramic products with a thickness of 0.2 mm to 3 mm, and has the advantages of high production speed, high degree of automation, uniform structure, and good product quality.
4, isostatic pressing
Isostatic molding utilizes the incompressibility and uniform transfer force of the liquid medium to place the sample in a high pressure vessel containing the liquid and subjected to the same pressure as in the same depth of still water.
The preform prepared by the method has the characteristics of high density and uniformity, and small stress in the embryo, and the binder can be used less or not.
Dry pressing isostatic pressing: isostatic pressing on a dry press basis. This is the most efficient, lowest cost, and best performing method for making simple shapes.
Third, the discharge of rubber:
Discharge: Remove organic matter from the embryo by heating or other physicochemical methods.
By sintering, the pores in the formed body can be reduced, the bonding between the particles can be increased, and the mechanical strength can be improved. Discharge and sintering can be carried out in the same equipment.
Degreasing before sintering, there are three main stages of degreasing:
(1) Low temperature section from room temperature to 200 degrees Celsius: Paraffin wax and stearic acid with relatively small molecular weight are mainly melted and decomposed.
(2) Medium temperature section of 200 to 400 degrees Celsius: mainly oxidizes, decomposes and removes polypropylene having a relatively large molecular weight.
(3) Short temperature of 400 to 600 degrees Celsius: completely remove a small amount of residual binder.
Fourth, CNC grinding
Grinding is the finishing of the fuselage, the curve of the fuselage is softer and the look is more comfortable. During ceramic grinding, brittle stripping of materials is accomplished by the formation or extension, spalling and fragmentation of voids and cracks.
Five, grinding and polishing
Grinding is to achieve rapid thinning, and the mechanism of material stripping is mainly rolling and crushing.
Polishing is the use of a fine abrasive elastoplastic polishing machine to rub the surface of the workpiece, plastically flow the surface of the workpiece, generate fine chips, use the elasticity and cushioning effect of the flannel, close to the surface of the porcelain, and remove the remaining from the previous process. 加工, scratches, rubbing and other processing marks to obtain a smooth surface.
Six, laser / PVD
Laser is a marking method that uses a high-energy-density laser to locally irradiate a workpiece to vaporize the surface layer or cause a chemical reaction of color change, thereby leaving a permanent mark.
PVD: The process of transferring a substance or molecule from a source to a surface of a substrate using physical processes.
Seven, AF (Anti-fingerprint, anti-fingerprint) processing
The anti-fingerprint treatment uses the principle of lotus leaf to deposit a layer of nano-chemical material on the surface of the ceramic by evaporation to minimize the surface tension of the ceramic. It has strong hydrophobicity, anti-fingerprint and anti-oil resistance, making the ceramic surface not easy to produce. Good fingerprint and wear resistance.
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