CN103801697B - A metal paste 3D printing moldless gel forming method - Google Patents

Abstract

The invention provides a kind of metal slip 3D to print without mould gel forming method, 3D printing technique is combined with gel shaped technology, gel shaped technique is utilized to prepare metal slip, the raw material printed using this slip as 3D, then 3D printing device is utilized to print according to data model layering, make metal slip rapid solidification by the addition controlling initator and catalyst, successively accumulation forms metal body, and drying, sintering obtain large scale, complicated shape metal parts product.The method can prepare the part comprising the conventional gel such as enclosed cavity, complicated inner cavity casting and cannot prepare, utilize 3D printing technique direct forming base substrate, without mould development expense, single-piece, small lot batch manufacture are with the obvious advantage, and require low to powder stock, and process stabilizing is reliable, strong operability, fugitive rate consuming time is high, and cost is low, is conducive to the industrialization that 3D printing technique prepares large scale, complicated shape metal parts.

Description

A metal paste 3D printing moldless gel forming method

technical field

The invention relates to a metal powder forming technology, which belongs to the technical field of metal parts preparation, and in particular provides a method for preparing large-sized and complex-shaped metal parts by 3D printing of metal slurry without mold gel forming.

Background technique

3D printing, a type of rapid prototyping, is a technology based on a three-dimensional data model, using powder-like bondable materials, and constructing objects by layer-by-layer printing. 3D printing is usually realized by using digital technology material printers. It is often used to manufacture models in mold manufacturing, industrial design and other fields, and is now gradually used for direct manufacturing of products. The basic process is: divide the 3D model into several layers in the computer, use the 3D printing equipment to layer graphics according to the data model on a plane, sinter or bond materials such as plastics and metals together, and then superimpose them layer by layer. stand up. Through the accumulation of different graphics in each layer, a three-dimensional object is finally formed.

Metal parts 3D printing technology, as the most cutting-edge and most potential technology in the entire 3D printing system, is an important development direction of advanced manufacturing technology. At present, stainless steel, titanium-based, and nickel-based alloys have been prepared by 3D printing technology, and metal parts with almost arbitrary shapes and metallurgical bonding can be directly obtained. However, the cost of existing 3D printing technology is very high. On the one hand, due to the high cost of 3D printing equipment, heating systems such as lasers and electron beams are required to melt the powder. On the other hand, the cost of raw materials is high. Good, excellent fluidity, fine and uniform particle size, and the entire forming process is time-consuming and inefficient, which makes the production cost of a single product remain high.

Gel injection molding is a new type of wet forming process. It mainly prepares slurry with low viscosity and high solid phase content, and then polymerizes the organic monomer in the slurry to solidify the slurry in situ, so as to obtain high strength, Green body with high density and excellent uniformity. The basic process is as follows: the organic monomer and solvent are prepared into a premixed solution with a certain concentration, and the powder is added to form a slurry with low viscosity and high solid phase content. After adding the initiator and catalyst, the slurry is injected into a non-porous mold. The organic monomers in the slurry are cross-linked and polymerized to form a three-dimensional network polymer gel, and the slurry is bonded and solidified in situ to form a green body, which is dried, degummed and sintered to obtain parts. Compared with the traditional forming process, gel injection molding has the advantages of easy forming of large-size and complex-shaped parts, high green body strength, and low organic content. It has advantages in iron-based, stainless steel, titanium-based, and aluminum-based powder metallurgy parts. Broad application prospects. However, the gel injection molding technology first needs to prepare a mold, and the cost of single-piece and small-batch production is high, and some parts with complex shapes cannot be prepared into molds, such as closed cavities, complex inner cavities, etc., making gel injection molding Application is restricted.

The invention provides a method for preparing large-sized and complex-shaped metal parts by combining 3D printing technology with gel forming technology. The gel forming process is used to prepare viscous metal slurry, which can be controlled by the initiator and catalyst. The added amount solidifies rapidly. The slurry is used as the raw material for 3D printing, and the 3D printing equipment is used to print layers according to the data model. The metal slurry is rapidly solidified and accumulated layer by layer to form a metal body, and then dried and sintered to obtain metal parts. Compared with the metal 3D printing process, it has low cost, low requirement for metal powder, short time consumption and high efficiency. Compared with traditional gel injection molding, no mold is required, and it is highly adaptable to the size and shape of parts. At present, there are no related reports on the method of preparing large-size and complex-shaped metal parts by using metal slurry 3D printing without mold gel forming.

Contents of the invention

The purpose of the present invention is to provide a method for preparing large-sized and complex-shaped metal parts by 3D printing of metal slurry without mold gel forming. The metal slurry is prepared by using the gel forming process as a raw material for 3D printing, and then the metal slurry is used as a raw material for 3D printing. The printing technology prepares the metal body, and after drying and sintering, large-sized and complex-shaped metal parts are obtained. The specific process and parameters are as follows:

1) Prepare the premix solution: Mix the organic monomer hydroxyethyl methacrylate (HEMA) and the solvent toluene in a certain proportion to form a premix solution. The concentration of the organic monomer HEMA is 30vol.%~50vol.%. It can quickly polymerize and gel by controlling the amount of initiator and catalyst added;

2) Preparation of metal slurry: Add metal powder with an average particle size of 5-50 μm to the above premix to prepare a slurry with a solid phase content of 40vol.%~60vol.%, and then add oil with a powder mass of 0.01wt~0.2wt% Acid improves slurry fluidity;

3) Data modeling: Use 3D modeling software to design part models of the required structural shape, especially large-scale part models with closed cavities and complex inner cavities, and slice the part models in layers with a thickness of 0.05 mm~0.25mm, get the 3D model data of the part;

4) 3D printing: import the 3D model data of the part into the 3D printing equipment, add 0.1~1wt.% initiator benzoyl peroxide, 0.5~3mmol/L (relative to the premixed solution) into the metal slurry Volume) catalyst dimethylaniline, after uniform mixing, print according to the three-dimensional data model, after layer printing, the organic monomer in the paste is chemically cross-linked to form a three-dimensional network polymer gel, so that the metal paste can be quickly solidified , accumulate layer by layer to form green body;

5) Body drying and degumming: The metal body is vacuum-dried at 60°C~100°C for 2~8h, and then the part body is kept at 300°C~600°C for 3~6h under the condition of argon flow atmosphere for degumming deal with;

6) Green body sintering: Under vacuum conditions, sinter the green body at a temperature range of 600-1500°C for 2-4 hours to obtain the required complex-shaped metal parts.

Compared with the prior art, the present invention has the following characteristics:

1) Strong adaptability to the shape of parts: 3D printing can produce large-sized and complex-shaped parts that cannot be prepared by traditional gel injection molding, including closed cavities and complex inner cavities;

2) No mold: When using the traditional gel injection molding process to prepare parts, it is first necessary to prepare a mold, then prepare a slurry and inject it into the mold to form a green body, while the present invention uses metal slurry 3D printing to directly form a green body without a mold Development costs, single piece and small batch production have obvious advantages;

3) Low requirements for powder raw materials: direct 3D printing of metals has high requirements for powder raw materials, and requires powders with good sphericity, excellent fluidity, fine and uniform particle size, and the melting-cooling process time is short when preparing alloys. Alloy powder must be selected for uniformity; and the present invention has low requirements for powder raw materials, and elemental powder can be used;

4) Ease of industrialization: Compared with metal direct 3D printing, the present invention has low cost, high reliability and strong operability, and is convenient for industrialized production.

Detailed ways

Implementation example 1: Using stainless steel powder slurry to 3D print moldless gel forming to prepare large-sized and complex-shaped stainless steel parts

1) Prepare the premix solution: mix the organic monomer hydroxyethyl methacrylate (HEMA) and the solvent toluene in a certain proportion to form a premix solution. The concentration of the organic monomer HEMA is 50vol.%. Rapid polymerization and gelation with the addition of additives and catalysts;

2) Preparation of stainless steel powder slurry: adding stainless steel powder with an average particle size of 20 μm to the above premix to prepare a slurry with a solid phase content of 60vol.%, and then adding 0.1wt% oleic acid to improve the fluidity of the slurry;

3) Data modeling: Use 3D modeling software to design large-scale part models with the required structural shape, especially large-scale part models with closed cavities and complex inner cavities, and perform layered slice processing on the part models. 0.05mm, get the three-dimensional model data of the part;

4) 3D printing: Import the 3D model data of the part into the 3D printing equipment, add stainless steel powder mass 1wt.% initiator benzoyl peroxide, 0.5mmol/L (relative to the volume of the premix) Catalyst dimethylaniline, uniformly mixed and printed according to the three-dimensional data model, the organic monomer in the slurry after layered printing is chemically cross-linked to form a three-dimensional network polymer gel, so that the metal slurry is rapidly solidified, layer by layer Accumulate to form a green body;

5) Body drying and degumming: vacuum dry the metal body at 60°C for 8 hours, and then degumming the part body at 600°C for 3 hours under a flowing atmosphere;

6) Green body sintering: Under vacuum conditions, sinter the green body at a temperature range of 1350°C for 2 hours to obtain the required large-sized and complex-shaped stainless steel parts.

Implementation example 2: Using titanium powder slurry to 3D print moldless gel forming to prepare large-sized and complex-shaped pure titanium parts

1) Prepare the premix solution: Mix the organic monomer hydroxyethyl methacrylate (HEMA) and the solvent toluene in a certain proportion to form a premix solution. The concentration of the organic monomer HEMA is 30vol.%. Rapid polymerization and gelation with the addition of additives and catalysts;

2) Preparation of metal slurry: adding titanium powder with an average particle size of 50 μm to the above premix to prepare a slurry with a solid phase content of 40vol.%, and then adding oleic acid with a powder mass of 0.2wt% to improve the fluidity of the slurry;

3) Data modeling: Use 3D modeling software to design large-scale part models with the required structural shape, especially large-scale part models with closed cavities and complex inner cavities, and perform layered slice processing on the part models. 0.25mm, get the three-dimensional model data of the part;

4) 3D printing: Import the 3D model data of the part into the 3D printing equipment, add 0.1wt.% of the initiator benzoyl peroxide of the powder mass, 3mmol/L (relative to the volume of the premix) into the metal slurry Catalyst dimethylaniline, uniformly mixed and printed according to the three-dimensional data model, the organic monomer in the slurry after layered printing is chemically cross-linked to form a three-dimensional network polymer gel, so that the metal slurry is rapidly solidified, layer by layer Accumulate to form a green body;

5) Body drying and degumming: the metal body is vacuum-dried at 100°C for 2 hours, and then the part body is kept at 300°C for 6 hours under the condition of argon flow atmosphere for degumming treatment;

6) Green body sintering: Under vacuum conditions, sinter the green body at 1200°C for 4 hours to obtain the required large-sized and complex-shaped pure titanium parts.

Claims (1)

1. A metal slurry 3D printing moldless gel forming method, characterized in that: Step 1. Prepare the premix solution: mix the organic monomer hydroxyethyl methacrylate and the solvent toluene in a certain proportion to form a premix solution. The concentration of the organic monomer hydroxyethyl methacrylate is 30vol.%-50vol.%; Step 2. Prepare metal slurry: add metal powder with an average particle size of 5-50 μm to the above premix to prepare a slurry with a solid phase content of 40vol.%-60vol.%, and then add 0.01wt-0.2wt% of the metal powder Oleic acid improves slurry fluidity; Step 3. Data modeling: Use 3D modeling software to design a large-scale part model with a closed cavity and a complex inner cavity, and slice the part model in layers. The thickness of the layer is 0.05mm-0.25mm, and the 3D part is obtained. model data; Step 4, 3D printing: Import the 3D model data of the part into the 3D printing equipment, add 0.01-1wt.% of the powder mass to the metal slurry as the initiator benzoyl peroxide and 0.1-3mmol/L relative to the volume of the premix The catalyst dimethylaniline is mixed uniformly and printed according to the three-dimensional data model. After layer printing, the organic monomers in the slurry form a three-dimensional network polymer gel through chemical cross-linking, so that the metal slurry is rapidly solidified and gradually The layers are accumulated to form a green body; Step 5. Body drying and degumming: The metal body is vacuum-dried at 60°C-100°C for 2-8h, and then the part body is kept at 300°C-600°C for 3-6h under the condition of argon flow atmosphere. Degumming treatment; Step 6. Green body sintering: under vacuum condition, sinter the green body after degumming treatment in the temperature range of 600-1500° C. for 2-4 hours to obtain the required metal parts.