CN1539571A - Preparation method of porous gypsum mold - Google Patents

Abstract

The invention discloses a method for preparing a porous gypsum casting mold, which belongs to the field of composite material preparation. The method is as follows: use a porous gypsum mold to form a porous gypsum mold, fully mix the gypsum powder, curing agent and toughened short fibers in proportion, add water to prepare a slurry, and inject it into the cavity of the metal mold from the top of the porous gypsum mold. , vibrate in a simple vacuum chamber, after the gas in the gypsum slurry is discharged, continue to replenish the slurry to fill the cavity, and then let it stand still, after the gypsum is solidified, dewax and dry in an oven to obtain a porous gypsum casting type. The porous gypsum mold prepared by the invention is suitable for the casting shape of the round bar self-generated gradient composite material prepared by the electromagnetic separation method, and can be easily assembled and disassembled in the electromagnetic separation device; the porous gypsum mold has low requirements on manufacturing equipment and few technological processes , Low cost, made of short fiber reinforced gypsum material, which not only ensures sufficient strength, but also has good collapsibility and can be recycled.

Description

Preparation method of porous gypsum mold

technical field

The invention relates to a method for preparing a gypsum casting mold, in particular to a method for preparing a porous gypsum casting mold for preparing self-generated gradient composite materials by electromagnetic separation. It belongs to the field of composite material preparation.

Background technique

In recent years, the application of various electromagnetic phase separation techniques in the preparation of gradient/surface composite materials has been extensively studied. Combination of those) After that, electromagnetic force is generated on the autogenous phase and it migrates to the surface layer of the alloy liquid. After the alloy liquid solidifies in the mold, an autogenous gradient/surface composite material with surface-enriched autogenous phase particles is formed.

In the existing self-generated gradient composite materials prepared by electromagnetic phase separation technology, single-hole separators are mostly used. After literature search, it was found that "Microstructure and Properties of Hypereutectic Al-Si Gradient Composite Materials" published by Li Ke et al. ("Chinese Journal of Nonferrous Metals", 2002, 12(3): pp.521-524), the It is introduced that the alternating magnetic field is applied to the cylindrical melt by means of an external coil induction alternating magnetic field, and the generated electromagnetic force can make the self-generated phase segregate to the outer surface of the melt, and by selecting the appropriate parameters of the electromagnetic force, the The round rod-shaped and tubular gradient composite materials with primary Si phase reinforced outer surface can only be molded one at a time due to the use of a single-hole separator, and the efficiency is low.

Contents of the invention

The purpose of the present invention is to address the deficiencies and defects of the prior art, and propose a method for preparing a porous gypsum mold, so that it can be used in the preparation of self-generated gradient composite materials by electromagnetic separation. Applying an alternating magnetic field, using the conductivity difference between the alloy liquid and the self-generated phase, the self-generated phase with low conductivity is segregated to the outer surface of the matrix material, so that the size and volume fraction of the self-generated reinforcing phase are continuous along the radial direction Gradient distribution, after the alloy liquid is solidified in the porous gypsum casting, a gradient reinforced composite rod with high surface hardness and wear resistance, and can maintain the toughness of the core can be obtained.

The present invention is achieved through the following technical proposals. The method of the present invention is as follows: a porous gypsum casting mold is formed by using a porous gypsum mold, and the gypsum powder, curing agent and toughened short fibers are fully mixed in proportion, and then water is added to form a slurry. The top of the porous gypsum molding mold is injected into the cavity of the metal mold, and vibrates in a simple vacuum chamber. After the gas in the gypsum slurry is discharged, continue to replenish the slurry to fill the cavity, and then stand still. Dewax in medium and dry to get porous gypsum mold.

The inventive method is described further below, and concrete steps are as follows:

1. Weigh 1-10% resin curing agent and 1-30% toughening short fiber according to the weight percentage of gypsum powder, and the rest is gypsum powder for casting;

2. Add the three materials into the mixer for full stirring and mixing;

3. Use the paraffin core casting mold to preform several round rod-shaped paraffin cores with a diameter of 3-50 mm, assemble them into a porous plaster molding mold, and pass the round rod-shaped paraffin through the through hole on the top cover of the mold and the blind hole on the base. The core is fixed in the metal mold cavity between the top cover and the base;

4. Inject the fully mixed gypsum slurry into the cavity of the metal mold from the sprue of the top cover of the porous gypsum molding mold until it is full;

5. Vibrate the whole porous gypsum molding mold in a simple vacuum chamber for 2-10 minutes. After the gas in the gypsum slurry is discharged, continue to replenish the slurry to fill the cavity;

6. After standing for 6-8 hours, remove the solidified plaster cast;

7. Dewax the porous gypsum mold with a round rod-shaped paraffin core in an oven at 300-600°C;

8. Continue drying for 8-12 hours to obtain a porous plaster mold.

The porous gypsum casting mold prepared by the invention has a cylindrical appearance, in which a plurality of axially penetrating circular holes are uniformly distributed, and the wall thickness of each place remains consistent. The outer diameter of the porous gypsum mold is up to 300mm. According to the length and diameter of the prepared rod, the diameter of the inner hole of the porous gypsum mold is selected within the range of 3-50mm, and the length of the porous gypsum mold is 30-300mm. Select within the range.

The porous gypsum casting mold prepared by the present invention is suitable for the casting shape of the round rod self-generated gradient composite material prepared by the electromagnetic separation method, and can be easily assembled and disassembled in the electromagnetic separation device; The self-generated gradient reinforced composite material forms a high-hardness self-generated phase reinforced layer distributed along the radial gradient on the outer surface with a certain thickness. The wear resistance of the surface layer is better than that of the homogeneous composite material, and the central matrix is a eutectic structure, which ensures overall toughness; the porous gypsum mold prepared by this method has low requirements on manufacturing equipment, few technological processes, and low cost. It is made of short fiber reinforced gypsum material, which not only ensures sufficient strength, but also has good collapsibility recycle and re-use.

Detailed ways

In conjunction with the content of the inventive method, the following examples are provided:

Example 1

A porous gypsum mold with an outer diameter of 50 mm and a length of 30 mm is manufactured, and the number of circular holes with an inner diameter of 3 mm is 61. Specific steps are as follows:

1. Take by weighing 1% of resin curing agent and 1% of toughening short fiber by weight percentage of gypsum powder, and the rest are gypsum powder for casting;

2. Add the three materials into the mixer for full stirring and mixing;

3. Use the paraffin core casting mold to preform a round rod-shaped paraffin core with a diameter of 3 mm, assemble it into a porous plaster molding mold, and fix the round rod-shaped paraffin core through the through hole on the top cover of the mold and the blind hole on the base In the metal mold cavity between the top cover and the base;

4. Inject the fully mixed gypsum slurry into the cavity of the metal mold from the sprue of the top cover of the porous gypsum molding mold until it is full;

5. Vibrate the whole porous gypsum molding mold in a simple vacuum chamber for 2 minutes. After the gas in the gypsum slurry is discharged, continue to replenish the slurry to fill the cavity;

6. After standing for 6 hours, remove the solidified plaster cast;

7. Dewaxing the porous plaster mold with a round rod-shaped paraffin wax core in an oven at 300°C;

8. Continue drying for 8 hours to obtain a 61-hole porous plaster mold with an inner diameter of 3 mm.

Implementation effect: the prepared porous gypsum mold has a cylindrical appearance, in which up to 61 axially penetrating round holes are evenly distributed, which can ensure consistent wall thickness everywhere. The outer diameter of the porous gypsum mold is 50mm, and the length is 30mm. It is suitable for the casting of round rod self-generated gradient composite materials prepared by electromagnetic separation method, and can be easily assembled and disassembled in the electromagnetic separation device. Using this porous gypsum casting form to prepare a round rod-shaped self-generated gradient reinforced composite material with a diameter of 3mm and a length of 30mm, a high-hardness self-generated phase reinforced layer with a certain thickness is formed on the outer surface along the radial gradient, and the surface layer is wear-resistant. It is superior to the composite material with homogeneous body, and the central matrix is eutectic structure, which ensures the overall toughness.

Example 2

A porous plaster mold with an outer diameter of 150 mm and a length of 150 mm is manufactured, and the number of circular holes with an inner diameter of 20 mm is 19. Specific steps are as follows:

1. Take by weighing 5% of resin curing agent and 15% of toughened short fibers by weight percentage of gypsum powder, and the rest are gypsum powder for casting;

2. Add the three materials into the mixer for full stirring and mixing;

3. Preform 19 round rod-shaped paraffin cores with a diameter of 20mm with the paraffin core casting mold, assemble into a porous gypsum mold, pass the through hole on the top cover of the mold and the blind hole on the base to put the round rod paraffin core The core is fixed in the metal mold cavity between the top cover and the base;

4. Inject the fully mixed gypsum slurry into the cavity of the metal mold from the sprue of the top cover of the porous gypsum molding mold until it is full;

5. Vibrate the entire porous gypsum molding mold in a simple vacuum chamber for 5 minutes. After the gas in the gypsum slurry is discharged, continue to replenish the slurry to fill the cavity;

6. After standing for 7 hours, remove the solidified plaster cast;

7. Dewax the porous plaster mold with a round rod-shaped paraffin core in an oven at 450°C;

8. Continue drying for 10 hours to obtain a 19-hole porous plaster mold with an inner diameter of 20 mm.

Implementation effect: The prepared porous gypsum mold has a cylindrical appearance, and up to 19 axially penetrating round holes are evenly distributed in it, which can ensure consistent wall thickness everywhere. The outer diameter of the porous gypsum mold is 150mm, and the length is 150mm. It is suitable for the casting of round rod self-generated gradient composite materials prepared by electromagnetic separation method, and can be easily assembled and disassembled in the electromagnetic separation device. Using this porous gypsum casting to prepare a round rod-shaped self-generated gradient reinforced composite material with a diameter of 20 mm and a length of 150 mm, a high-hardness self-generated phase reinforced layer with a certain thickness is formed on the outer surface along the radial gradient, and the surface layer is wear-resistant. It is superior to the composite material with homogeneous body, and the central matrix is eutectic structure, which ensures the overall toughness.

Example 3

A porous plaster mold with an outer diameter of 300 mm and a length of 300 mm is manufactured, and the number of circular holes with an inner diameter of 50 mm is 19. Specific steps are as follows:

1. Take by weighing 10% of resin curing agent and 30% of toughened short fibers according to the weight percentage of gypsum powder, and the rest are gypsum powder for casting;

2. Add the three materials into the mixer for full stirring and mixing;

3. Preform 19 round rod-shaped paraffin cores with a diameter of 50mm with a paraffin core mold, assemble into a porous gypsum mold, pass the through hole on the top cover of the mold and the blind hole on the base to put the round rod paraffin core The core is fixed in the metal mold cavity between the top cover and the base;

4. Inject the fully mixed gypsum slurry into the cavity of the metal mold from the sprue of the top cover of the porous gypsum molding mold until it is full;

5. Vibrate the porous gypsum mold as a whole in a simple vacuum chamber for 10 minutes. After the gas in the gypsum slurry is discharged, continue to replenish the slurry to fill the cavity;

6. After standing for 8 hours, remove the solidified plaster cast;

7. Dewax the porous plaster mold with a round rod-shaped paraffin core in an oven at 600°C;

8. Continue drying for 12 hours to obtain a 19-hole porous plaster mold with an inner diameter of 50 mm.

Implementation effect: The prepared porous gypsum mold has a cylindrical appearance, and up to 19 axially penetrating round holes are evenly distributed in it, which can ensure consistent wall thickness everywhere. The outer diameter of the porous gypsum mold is 3000mm, and the length is 300mm. It is suitable for the casting of round rod self-generated gradient composite materials prepared by electromagnetic separation method, and can be easily assembled and disassembled in the electromagnetic separation device. Using this porous gypsum casting form to prepare a round rod-shaped self-generated gradient reinforced composite material with a diameter of 50mm and a length of 300mm, a high-hardness self-generated phase reinforced layer with a certain thickness is formed on the outer surface along the radial gradient, and the surface layer is wear-resistant. It is superior to the composite material with homogeneous body, and the central matrix is eutectic structure, which ensures the overall toughness.

Claims (4)

1, a kind of preparation method of graphite casting mold, it is characterized in that, method is as follows: adopt graphite type mould moulding graphite casting mold, add water after land plaster, curing agent and toughness reinforcing short fiber fully mixed in proportion and be deployed into slurry, inject the die cavity of metal pattern from graphite type mould top, in the simple vacuum chamber, vibrate, after waiting to discharge the gas in the gypsum slurry, continue to replenish slurry and fill up die cavity, leave standstill subsequently, after treating that gypsum solidifies, dewaxing and oven dry promptly obtain the graphite casting mold in baking oven.

2, the preparation method of graphite casting mold according to claim 1 is characterized in that, below the inventive method is further described, and concrete steps are as follows:

(1) percentage by weight by land plaster takes by weighing 1-10% resin curing agent and the toughness reinforcing short fiber of 1-30%, and all the other are the casting land plaster;

(2) three kinds of materials being added batch mixers fully stirs and mixes;

(3) the percentage by weight adding compound of pressing 5-50% continues to stir and mix;

(4) with the some diameters of paraffin core mold moulding in advance be the pole shape paraffin core of 3-50mm, be assembled into graphite type mould, pole shape paraffin core be fixed in the metal pattern die cavity between top cover and the base by the through hole on the top cover of this mould and the blind hole on the base;

(5) with the die cavity of well-mixed gypsum slurry, till filling with from the sprue gate injection metal pattern of graphite type mould top cover;

(6) graphite type mould integral body is vibrated 2-10 minute in the simple vacuum chamber, wait to discharge the gas in the gypsum slurry after, continue to replenish slurry and fill up die cavity;

(7) leave standstill 6-8 hour after, with the gypsum mould demoulding of solidifying;

(8) the graphite casting mold that will have a pole shape paraffin core dewaxes in 300-600 ℃ baking oven;

(9) continue oven dry 8-12 hour, obtain the graphite casting mold.

3, the preparation method of graphite casting mold according to claim 1 and 2 is characterized in that, the graphite casting mold of preparation has cylindrical exterior, wherein is evenly distributed with the circular hole of a plurality of axial perforations, and wall thickness is consistent everywhere.

4, the preparation method of graphite casting mold according to claim 1 and 2, it is characterized in that, the external diameter up 300mm of the graphite casting mold of preparation, the diameter of graphite casting mold inner circular aperture is chosen in the scope of 3-50mm, and the length of graphite casting mold is chosen in the scope of 30-300mm.