CN107696233A - A kind of ceramic 3D printing equipment - Google Patents

Abstract

The present invention proposes a kind of ceramic 3D printing equipment, including printed for ceramic slurry 3D printing device, liftable low-temperature working stage apparatus and can temperature adjustment cooling device.The present invention realizes the 3D printing of the ceramic slurry based on freezing gelling characteristic, easily realizes the commercial application of high-performance ceramic product；The present invention realizes ceramics just " shallow " the freezing d type of base, defrosting and the whole process of " depth " freezing solidification, simple in equipment by temperature control system.

Description

A kind of ceramic 3D printing equipment

technical field

The invention relates to a ceramic 3D printing device, which belongs to the technical field of ceramic 3D printing.

Background technique

Ceramic 3D printing has the characteristics of layer-by-layer printing and molding. Compared with traditional ceramic manufacturing processes, the biggest advantages are high manufacturing precision, short production cycle, personalized production, diversity of production materials and relatively low production cost. At present, the common 3D printing methods mainly include: Laminated Objected Manufacturing (LOM), Fused Deposition Modeling (Fused Deposition Modeling, FDM), Stereo-Lithography (SLA), Selective Laser Flame (Selective) Laser Melting, SLM), Selective Laser Sintering (Selective Laser Sintering, SLS), three-dimensional printing method (3D Printing, 3DP), etc.

However, these unique 3D printing technologies are difficult to adapt to a variety of materials. It is often necessary to develop a corresponding 3D printing technology for a certain characteristic of ceramic properties. The cost is high, and the mechanical properties of the molded ceramic parts are not good. ideal. At present, the direct 3D rapid prototyping process of ceramics at home and abroad is not yet mature. The patent (CN104108131A) introduces a 3D printing molding method for ceramic materials. The working platform of the 3D printing equipment is placed in the freezing space, and the slurry with freezing and gelling properties is sprayed on the freezing platform to obtain a 3D printed ceramic blank. body.

The way of ceramic 3D printing based on slurry with freeze-gelation properties is a new idea to realize ceramic 3D printing, which is still in the research stage, and there is no printing device dedicated to realize the process.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and propose a ceramic 3D printing device based on cryogelation.

The technical solution of the present invention: a ceramic 3D printing equipment, including a 3D printing device for ceramic slurry printing, a liftable low-temperature working platform device, and a temperature-adjustable cooling device;

The 3D printing device includes a 3D printer head, a three-dimensional movable mobile structure for installing the 3D printer head, and a control module for controlling the 3D printer head and the mobile structure. The 3D printer head on the liftable low-temperature working platform device extrudes ceramic slurry along a predetermined path;

The specific design of the 3D printing device is a well-known technology in the art, as long as the ceramic slurry can be extruded according to the predetermined route and precision, for example, the ceramic printer design in CN201610117850.9 can be used.

The liftable low-temperature working platform device includes a platform lifting mechanism and a low-temperature working platform. The platform lifting mechanism realizes the lifting of the low-temperature working platform. During 3D printing, after each layer is printed, the platform lifting mechanism makes the low-temperature working platform The distance down to the thickness of one layer of the low-temperature environment chamber;

The temperature-adjustable cooling device includes a temperature control system, a low-temperature environment chamber, a low-temperature medium storage tank, a thawing medium storage tank, and a freezing medium storage tank. The temperature control system includes a temperature controller, a temperature sensor, and a flow control valve. The low-temperature medium , thawing medium and freezing medium storage tanks are respectively connected to the low-temperature environment chamber through the medium conveying pipeline, the flow control valve is installed on the medium conveying pipeline, the temperature sensor is installed in the low-temperature environment chamber to measure the temperature in the low-temperature environment chamber, and the temperature controller controls the flow control The valve realizes the communication between the storage tanks of different media and the low-temperature environment chamber, so that the low-temperature environment chamber can maintain different temperatures in different predetermined programs.

The low-temperature medium can be low-temperature gas or freezing liquid, and the temperature in the cooling container can be at the first preset low temperature. The first preset low temperature is -10°C to -20°C, which is the working temperature of 3D printing. That is, the temperature of the low-temperature working platform during 3D printing.

The thawing medium may be a substance such as gas or liquid, and it only needs to realize that the temperature in the cooling container is at a preset thawing temperature, and the preset thawing temperature is 25°C-40°C.

The freezing medium can be low-temperature gas or freezing liquid, and the temperature in the cooling container can be achieved at the second preset low temperature. The second preset low temperature is the cooling gel temperature of the ceramic slurry, and the second preset low temperature is ≤-80 ℃.

During the 3D printing process of the low-temperature environment chamber, the temperature control system controls the low-temperature environment chamber to communicate with the low-temperature medium storage tank, so that the temperature in the low-temperature environment chamber remains at the first preset low temperature; after the 3D printing is completed, the 3D printed After the ceramic blank enters the low-temperature environment chamber as a whole, the temperature control system controls the low-temperature environment chamber to be disconnected from the low-temperature medium storage tank, and connected to the thawing medium storage tank, so that the low-temperature environment chamber is kept at the preset thawing temperature, and the ceramic blank is subjected to 5~ Thaw for 10 minutes; after thawing, the temperature control system controls the low-temperature environment chamber to be disconnected from the thawing medium storage tank, and connected to the freezing medium storage tank, so that the low-temperature environment chamber is kept at the second preset low temperature to freeze and gel the ceramic blank.

The cryogelation of the ceramic preform can be carried out by adopting the prior art or the layer-by-layer cryogelation process provided by the present invention.

The cryogel of the ceramic preform adopts mode one or mode two to realize the layer-by-layer cryogel of the ceramic preform,

Method 1: Place the thawed ceramic preform in a low-temperature environment chamber, slowly inject a freezing medium (the second preset low temperature) from the bottom of the low-temperature environment chamber, and freeze and shape the ceramic preform layer by layer. The thickness of each layer is ≤ 1μm, that is, the height of the freezing medium injected each time is ≤1μm, and the freezing and holding time is not less than 0.5 minutes;

Method 2. The liftable low-temperature working platform device moves the thawed ceramic blanks out of the low-temperature environment chamber. The temperature in the low-temperature environment room is the second preset low temperature. Enter the low-temperature environment chamber (the temperature of the low-temperature environment chamber is the second preset low temperature), the entry speed is not greater than 1 μm/3min, and freeze and solidify layer by layer.

The present invention uses silica sol as the liquid phase of the preparation slurry to prepare ceramic slurry suitable for 3D printing, and performs layer-by-layer printing. With the help of 3D printing, the thickness of the ceramic layer is finely controlled. During the layer-by-layer printing process, each layer is directly printed on the printing platform. "Shallow" freezing of the printed paste (temperature control at the first preset low temperature), and then through the lifting mechanism, the printed part gradually enters the low temperature environment chamber (temperature control at the first preset low temperature) for heat preservation until printing At the end of the work, ensure that the water in the ceramic slurry is frozen to print the shape and obtain the ceramic blank; after the overall printing is completed, adjust the temperature in the low-temperature environment room to the thawing temperature, so that the obtained ceramic blank can be kept at this temperature. 5-10 minutes for rapid thawing, so that the frozen water phase in the preform is restored to the liquid phase; then the above-mentioned freezing method 1 or method 2 is used to realize the freezing and gelation of the ceramic preform layer by layer, and obtain a ceramic body with a microscopic layered structure ; Finally, the whole ceramic body is removed from the low-temperature environment chamber for drying and sintering, and high-performance layered 3D printed ceramic parts can be obtained.

Drying and sintering of green bodies is a well-known technology in the art, and can be selected according to specific material requirements.

The powder particle size and purity requirements for preparing ceramic slurry are well-known technologies in the art, and those skilled in the art can choose according to specific requirements.

The ceramic slurry of the present invention can add small molecular polyhydric alcohol organic matter (the addition amount is 0.5～3% of the liquid phase water mass in the ceramic slurry), and through the layer-by-layer slow control freezing adopted by the present invention, combined with small molecules Polyhydric alcohols can regulate the size and shape of ice crystals in the process of cryogelation of ceramic slurry, and can make the microscopic interface between the frozen layer formed in the layer-by-layer freezing process and the frozen layer microscopic interface form a jagged shape due to water crystallization. Micro-ice crystal structure, in the subsequent sintering, the formed ceramic rod-shaped crystals can grow in the micropores left by the micro-ice crystal structure, and form an interlayer structure in which ceramic rod-shaped crystals interweave in the microscopic interface between layers, thereby promoting the green body. Microscopic close bonding and good sintering properties of layered materials.

The beneficial effect of the present invention compared with prior art:

(1) The present invention realizes the 3D printing of the ceramic slurry based on the freezing and gelling characteristics, and easily realizes the industrial application of high-performance ceramic products;

(2) The present invention realizes the whole process of "shallow" freezing dimensioning, thawing and "deep" freezing and solidification of the ceramic blank through the temperature control system, and the equipment structure is simple;

(3) The present invention adopts a liftable low-temperature working platform device and a temperature control system, which can realize the layer-by-layer freezing control of the ceramic blank, so that the water crystallization between the macroscopic layer interfaces forms a jagged micro-ice crystal structure during the "deep" freezing process, It promotes the close bonding between the layers of the green body, ensures the good sinterability of the layered ceramics, and at the same time controls the freezing to form a microscopic thin layer (≤1μm) structure in the macroscopic layer of each layer. This layered structure can be greatly improved. The mechanical properties of ceramic materials, and give full play to the unique energy dissipation structure advantages of layered ceramics, overcome the fatal shortcomings of sudden fracture of ceramics, and greatly improve the reliability of ceramic materials.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2a, b are microstructures of ceramic materials obtained by the present invention.

detailed description

The present invention will be described in detail below in conjunction with specific examples and accompanying drawings.

As shown in Figure 1, the present invention includes a 3D printing device for ceramic slurry printing, a liftable low-temperature working platform device and a temperature-adjustable cooling device.

The 3D printing device includes a 3D printer head 1 for extruding ceramic slurry, a moving structure and a control module. The 3D printer head 1 is installed on the three-dimensionally movable mobile structure controlled by the control module. According to the design of model establishment and model layering, ceramic slurry is extruded along a predetermined path on the liftable low-temperature working platform.

The liftable cryogenic work platform device includes a cryogenic work platform 2 and a platform lifting mechanism. The platform lift mechanism includes a lifting screw 3 and a lifting controller 6. The lifting controller 6 controls the movement of the lifting screw 3 to realize the lifting of the low temperature working platform 2. During 3D printing, after each layer is printed, the lift controller 6 lowers the low-temperature working platform 2 to the distance of the thickness of one layer in the low-temperature environment chamber 5 .

The temperature-adjustable cooling device includes a medium inlet hole 4, a low-temperature environment chamber 5, a temperature sensor 7, a temperature controller 8, a low-temperature medium storage tank 9, a thawing medium storage tank 10, and a cooling medium storage tank 11; the medium inlet hole 4 is installed on At the bottom of the low-temperature environment chamber 5, the temperature sensor 7 is installed on the top of the low-temperature environment chamber 5 to measure the temperature in the low-temperature environment chamber 5. The low-temperature medium storage tank 9, the thawing medium storage tank 10 and the cooling medium storage tank 11 pass through the medium delivery pipeline and The medium inlet hole 4 is connected with the low temperature environment chamber 5, the flow control valve 12 is installed on the medium conveying pipeline, and the temperature controller controls the flow control valve 12 to realize the communication between different storage tanks and the low temperature environment chamber 5, so that the low temperature environment chamber 5 can operate in different predetermined programs. Different temperatures are maintained in the low temperature environment chamber 5; the processing medium discharge hole on the low temperature environment chamber 5 is used to discharge the medium in the low temperature environment chamber 5 when the predetermined program is replaced.

Adopt the 3D printing Si ₃ N ₄ ceramic material of the present invention, prepare ceramic slurry, ceramic slurry is made of alkaline silica sol, silicon nitride powder, a small amount of sintering aid, carboxymethyl cellulose and glycerine that increase the plasticity of ceramic slurry The slurry is composed of alcohol, the amount of carboxymethyl fiber and glycerin is 1% of the mass of the liquid phase water in the ceramic slurry, and 1% of tetramethylammonium hydroxide is added as a dispersant, and the ball mill is mixed for 5 hours in a high-speed ball mill .

After the ceramic slurry is degassed, it is loaded into the 3D printer, and is continuously printed layer by layer through the 3D printer head 1. Each layer is printed on the low-temperature working platform 2 under the condition of -10～-20°C, so that the slurry printing process remains "shallow". "Freezing, Dimensional Printing for Ceramic Slurries. Every time a layer is printed, the lifting controller 6 controls the lifting screw 3 to lower the low-temperature working platform 2 to the distance of the thickness of one layer of the low-temperature environment chamber 5. At this time, the temperature controller 8 controls the flow control valve 12 to make the low-temperature environment chamber 5 and the low-temperature medium The storage tank 9 is connected, and the temperature sensor 7 measures the temperature in the low temperature control room as -15°C.

After the printing is finished, the printed preforms are quickly thawed as a whole. The temperature controller 8 controls the flow control valve 12 to connect the low-temperature environment chamber 5 with the thawing medium storage tank 10, so that the temperature in the low-temperature environment chamber 5 is kept at 30°C. The billet was thawed for 10 minutes, and the frozen water phase in the first billet was restored to the liquid phase again.

Immediately afterwards, the whole printed preform is "deeply" frozen. The temperature controller 8 controls the flow control valve 12 to connect the low-temperature environment chamber 5 with the cooling medium storage tank 11. The bottom of the low-temperature environment chamber 5 is slowly injected with the freezing medium through the medium inlet hole 4. Control the freezing temperature and freezing rate so that the blank enters the freezing medium gradually and slowly, and the entry speed is 1μm/3min to achieve layer-by-layer freezing control, realize the overall solidification of the printed part, and form a ceramic body with a certain strength.

The green body is dried and sintered to obtain a Si ₃ N ₄ ceramic material with a layered microstructure.

As can be seen from the microstructure of Figure 2a and b, the material is relatively dense and has good interlayer bonding. The material has a relatively obvious thin layer structure, and Si ₃ N ₄ ceramic rod-shaped crystal layers are formed between the microscopic layers, thereby promoting the microscopic Close bonding between layers and good sintering properties of the material.

Parts not described in detail in the present invention are well-known technologies for those skilled in the art.

Claims (8)

1. A kind of 1. ceramic 3D printing equipment, it is characterised in that：Including the 3D printing device, liftable printed for ceramic slurry Low-temperature working stage apparatus and can temperature adjustment cooling device；

   Described 3D printing device include 3D printing head, the moving structure that can be three-dimensional mobile for installing 3D printing head and Control the control module of 3D printing head and moving structure；Described liftable low-temperature working stage apparatus includes lifting platform Mechanism and low-temperature working platform, described platform lifting mechanism realize the lifting of low-temperature working platform；

   It is described can the cooling device of temperature adjustment include temperature control system, low temperature environment room, cryogenic media holding vessel, thaw Media storage tank and refrigerant storage tank, temperature control system include temperature controller, temperature sensor and flow control valve, low temperature Medium, defrosting medium and refrigerant storage tank are connected by medium delivery pipe road with low temperature environment room respectively, flow control valve On medium delivery pipe road, temperature sensor is arranged in low temperature environment room, measures the temperature in low temperature environment room, temperature control Instrument control flow control valve realizes that different medium storage tank connects with low temperature environment room, makes low temperature environment room in different preset programs It is middle to keep different temperature.
2. A kind of 2. ceramic 3D printing equipment according to claim 1, it is characterised in that：Described low temperature environment room is beaten in 3D During print, temperature control system control low temperature environment room connects with cryogenic media holding vessel, makes the temperature in low temperature environment room It is maintained at the first default low temperature；After the completion of 3D printing, after base at the beginning of the ceramics of 3D printing integrally enters low temperature environment room, temperature control System control low temperature environment room processed disconnects with cryogenic media holding vessel, is connected with defrosting media storage tank, protects low temperature environment room Hold in default thaw point, base at the beginning of ceramics is thawed；After defrosting, temperature control system control low temperature environment room is situated between with thawing Matter storage tank disconnects, and is connected with refrigerant storage tank, low temperature environment room is maintained at the second default low temperature and base at the beginning of ceramics is entered Row freezing gel.
3. A kind of 3. ceramic 3D printing equipment according to claim 2, it is characterised in that：Described first default low temperature for- 10 DEG C~-20 DEG C.
4. A kind of 4. ceramic 3D printing equipment according to claim 2, it is characterised in that：Described default thaw point is 25 DEG C~40 DEG C.
5. A kind of 5. ceramic 3D printing equipment according to claim 2, it is characterised in that：Described second presets low temperature ≤-80℃。
6. A kind of 6. ceramic 3D printing equipment according to claim 2, it is characterised in that：Described being carried out to base at the beginning of ceramics is cold Glue is congealed using successively freezing gel technique.
7. A kind of 7. ceramic 3D printing equipment according to claim 6, it is characterised in that：The first base freezing gel of described ceramics Employing mode one or mode two realize the first base of ceramics successively freezing gel,

   Mode one, by the ceramics after defrosting, just base is placed in low temperature environment room, and being slowly injected into freezing from low temperature environment room bottom is situated between Matter, successively freeze forming, every layer of freezing thickness≤1 μm, i.e., height≤1 of the refrigerant injected every time are carried out to base at the beginning of ceramics μm, freezing soaking time is not less than 0.5 minute；

   Mode two, by the ceramics after defrosting, just base removes low temperature environment room, low temperature environment to liftable low-temperature working stage apparatus Temperature is the second default low temperature in room, and by the ceramics after defrosting, just base persistently slowly enters liftable low-temperature working stage apparatus Into low temperature environment room, admission velocity is no more than 1 μm/3min, is successively freezed curing molding.
8. A kind of 8. ceramic 3D printing equipment according to claim 1, it is characterised in that：Added in described ceramic slurry small Molecule multi-hydroxy alcohol type organic, addition are 0.5~3% of liquid phase water quality in ceramic slurry.