CN100408232C - A kind of Ti6Al4V alloy gel injection molding method - Google Patents

Abstract

The invention discloses a Ti6Al4V alloy gel injection molding method, which belongs to the technical field of titanium alloy forming. The titanium alloy green body is prepared by gel injection molding technology, and then the titanium alloy is prepared by degreasing and sintering. The process includes: preparation of premix liquid, preparation of slurry, preparation of green body, drying and debinding of green body, and sintering of green body. The invention has the advantages of simple operation procedure, low equipment cost, and low mold cost; less organic content used, less green body shrinkage, and parts with complex shapes near net size can be prepared; the green body has high strength and can be processed Further machining; low organic content and easy removal.

Description

A kind of Ti6Al4V alloy gel injection molding method

technical field

The invention belongs to the technical field of titanium alloy forming, and in particular provides a Ti6Al4V alloy gel injection molding method, which realizes the preparation of low-cost and high-performance titanium alloy.

Background technique

Titanium and titanium alloys have low density, high specific strength, low elastic modulus, good high temperature strength, non-toxic and non-magnetic, excellent corrosion resistance and other properties, and are widely used in petrochemical, aerospace, automobile, bioengineering (good compatibility Sex), watches, environmental protection, golf equipment, spectacle frames and other fields. Therefore, the study of this material has always been a hot spot in the field of material research. At present, the relatively mature methods for preparing Ti6Al4V mainly include vacuum melting, precision casting, powder metallurgy and metal injection molding. Vacuum smelting and precision casting have defects, such as easy segregation of components and uneven structure, introduction of impurities, low production efficiency and high production cost. The traditional powder metallurgy method uses a simple three-step process of powder mixing-pressing-sintering to produce high-performance titanium alloys, but this method can only produce parts with simple shapes, and the production efficiency is low and the production cost is high. The metal injection molding method can prepare parts with complex shapes, but this method needs to mix a large amount of organic binder in the metal powder, so that the degreasing and wax removal process of the formed body takes a very long time, and the elimination of organic matter During the process, it is easy to cause defects or even collapse, and it is not suitable to form a large green body with an uneven structure and a complex inner cavity. At the same time, high O and C will remain (due to the decomposition of the binder during the removal of the binder). The gel injection molding method has short process time, low organic matter content, uniform product composition and structure, and accurate size, which can realize low-cost continuous production of titanium alloy parts. The method firstly mixes the Ti6Al4V powder with the premix liquid composed of monomer, cross-linking agent and deionized water, adds catalyst and initiator, injects it into the mold cavity, waits for in-situ solidification, demoulds it to form a preform, and then After degreasing and sintering, a titanium alloy with high performance is prepared.

Contents of the invention

The purpose of the present invention is to provide a Ti6Al4V gel injection molding method, which can produce titanium alloy parts with complex shapes and high dimensional accuracy in batches at low cost, so that the material can be widely used.

The invention adopts the gel injection molding technique to prepare the titanium alloy green body, and then prepares the titanium alloy through debinding and sintering. The specific process is:

a. Preparation of master mix

An organic monomer capable of generating free radicals is dissolved in deionized water to form a solution with a mass concentration of the monomer of 9% to 20%, and a crosslinking agent is added, the mass of which is 1/120 to 1/30 of the mass of the monomer.

b. Preparation of slurry

The powder is gas-atomized Ti6Al4V powder, or a powder prepared by hydrogenation-dehydrogenation Ti6Al4V powder and gas-atomized Ti6Al4V powder (wherein the mass percentage of gas-atomized Ti6Al4V powder is 60-100%). Add 450-600 grams of prepared powder to each 100 mL of premixed liquid, and stir evenly. This process may generate air bubbles, which can be defoamed by adding a defoamer (0.1-1% of the total mass of the powder);

c. Prepare green body

Add catalyst and initiator to the slurry (1 to 100 microliters of catalyst and 1 to 10% aqueous solution of initiator by mass fraction are added to each 100 milliliters of slurry), stir evenly and inject into the cavity of the mold, and wait for gelation After melting, the mold is demoulded to obtain a green body with a certain strength;

d. Green body drying and debinding

Dry the green body at 20°C-80°C for 1-50 hours, after the water is drained, the green body can be further machined to make its shape precise, and then deglue at a temperature of 300°C-500°C for 10- 30 minutes;

e. Green body sintering

The green body is sintered at 1200-1400°C for 0.5-3 hours at a vacuum degree of 10 ^-3 Pa to 10 ^-4 Pa to obtain complex parts with precise dimensions.

The organic monomer of the present invention is: one or more of acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; the crosslinking agent is: methylenebisacrylamide; the defoamer is: 1 to 3 kinds of isooctyl alcohol, fatty acid, and tributyl phosphate; the catalyst is: methylethylenediammonium; the initiator 1 to 2 types of potassium persulfate and ammonium persulfate.

Advantages of the invention

1. The slurry is liquid, can flow and fill the mold, and can prepare parts with complex shapes (the complexity of the parts depends on the manufacturing level of the mold);

2. The operation procedure is simple;

3. Low equipment cost, low mold cost. The material requirements for the mold are not high, glass, plastic, metal and wax are acceptable;

4. The content of organic matter used is less, the green body shrinks less, and parts with near net dimensions can be prepared;

5. Mass production is possible;

6. The green body has high strength and can be further machined;

7. Low organic content and easy to remove. Since all organic matter can be used in monomers and plasticizers in the premix liquid except for the solvent that can be discharged, the parts after sintering are of high purity.

Description of drawings

Fig. 1 is the preparation process flowchart of the present invention.

Detailed ways

Example 1:

The powder is prepared from hydrogenation-dehydrogenation Ti6Al4V powder and gas-atomized Ti6Al4V powder, wherein the mass percentage of gas-atomized Ti6Al4V powder is 90%. The concentration of acrylamide in the premix is 15%, and the mass ratio of acrylamide:methylenebisacrylamide is 90:1. Add 475 grams of prepared powder and 1 gram of defoamer isooctyl alcohol to every 100 mL of premix. After stirring evenly, add catalyst tetramethylethylenediammonium (25 μL per 100 mL of slurry), initiator ammonium persulfate (mass fraction 10%, add 15 μL per 100 mL of slurry), stir for 10 seconds, and quickly pour into the mold , in an oven at 60°C for 0.5 hours, demolded, put in an oven at 60°C for 6 hours, and take it out. At a vacuum degree of 10 ^-4 Pa, degrease at 350°C for 30 minutes, sinter at 1250°C for 3 hours, and cool in the furnace to obtain titanium alloy parts with better comprehensive mechanical properties and higher dimensional accuracy.

Example 2:

The concentration of hydroxyethyl methacrylate in the premix is 20%, and the mass ratio of hydroxyethyl methacrylate: methylenebisacrylamide is 30:1. Add 550 grams of aerosolized Ti6Al4V powder and 2 grams of defoamer fatty acid to each 100 mL of premixed solution. After stirring evenly, add catalyst tetramethylethylenediammonium (30 μL per 100 mL of slurry), initiator potassium persulfate (mass fraction 8%, add 50 μL per 100 mL of slurry), stir for 5 seconds, and quickly pour into the mold , vacuum-dried in an oven at 50°C for 1 hour, demolded, put in an oven and dried at 50°C for 15 hours, and took it out. At a vacuum of 10 ^-3 Pa, degrease at 400°C for 20 minutes, sinter at 1300°C for 2 hours, and cool in the furnace to obtain titanium alloy parts with good comprehensive mechanical properties and high dimensional accuracy.

Example 3:

The powder may be prepared from hydrogenation-dehydrogenation Ti6Al4V powder and gas-atomized Ti6Al4V powder, wherein the mass percentage of gas-atomized Ti6Al4V powder is 80%. The concentration of hydroxypropyl methacrylate in the premix is 20%, and the mass ratio of hydroxypropyl methacrylate:methylenebisacrylamide is 100:1. Add 500 grams of prepared powder and 2 grams of tributyl phosphate defoamer to every 100 mL of premixed solution. After stirring evenly, add catalyst tetramethylethylenediammonium (30 μL per 100 mL of slurry), initiator ammonium persulfate (mass fraction 10%, add 50 μL per 100 mL of slurry), stir for 5 seconds, and quickly pour into the mold In the middle, dry in an oven at 70°C for 0.5 hours, demould, put in an oven and dry at 70°C for 20 hours and take it out. At a vacuum degree of 10 ^-3 Pa, degrease at 350°C for 30 minutes, sinter at 1300°C for 2 hours, and cool in the furnace to obtain titanium alloy parts with good comprehensive mechanical properties and high dimensional accuracy.

Claims (1)

1. a Ti6Al4V alloy gel casting method adopts the gel casting technology to prepare the titanium alloy base substrate, prepares titanium alloy through degreasing and sintering again; It is characterized in that:

Technology is:

A, preparation premixed liquid

The organic monomer that can produce free radical is dissolved in the deionized water, is configured to monomer mass concentration and is 9%～20% solution, adds crosslinking agent, and its quality is 1/120～1/30 of a monomer mass;

B, preparation slurry

Powder is an aerosolization Ti6Al4V powder or formulated by hydrogenation-dehydrogenation Ti6Al4V powder and aerosolization Ti6Al4V powder, wherein, the mass percent of aerosolization Ti6Al4V powder is 60～100%, add powder 450～600 grams that configure in every 100mL premixed liquid, stir, add the defoamer froth breaking, addition is 0.1～1% of a powder gross mass;

C, preparation base substrate

Add catalyst and initator in slurry, it is 1～10% initiator solution that the slurry of every 100mL adds the catalyst of 1～100 μ L and mass fraction respectively, evenly stirs the back and injects cavity body of mould, treats the demoulding after the gelation, obtains base substrate;

D, body drying binder removal

With base substrate at 20 ℃～80 ℃ down dry 1～50h, its moisture is drained after, base substrate carries out machining, makes its shape accurate, then binder removal 10～30min under 300 ℃～500 ℃ temperature;

E, blank sintering

Base substrate is 10 ^-3Pa～10 ^-4The vacuum of Pa, 1200 ℃～1400 ℃ following sintering 0.5～3h obtain accurate in size complex parts;

Described organic monomer is one or more in acrylamide, hydroxy-ethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, the hydroxy propyl methacrylate; Described crosslinking agent is: methylene-bisacrylamide; Described defoamer is: isooctanol, aliphatic acid, tbp 1～3 kind; Described catalyst is: methyl second two ammoniums; Described initator is: potassium peroxydisulfate, ammonium persulfate 1～2 kind.

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