A bonded 3D printing similar material for complex geological models

Abstract

The present invention discloses a bonding type 3D printing similar material for complex geological models, comprising a powder material and ink, wherein the powder material comprises, by weight, 10-40 parts of heavily burned MgO, 5-30 parts of phosphate, 30-100 parts of barite powder, 8-25 parts of hemihydrate gypsum, and 50-100 parts of precision improvement components; the ink comprises 3-10% of a viscosity modifier, 0.5-2.5% of a solubilizing stabilizer, 0.1-0.8% of a surface tension modifier, and 0.0 1-0.1% defoamer, 3-6% moisturizer, 80-97% deionized water; the viscosity modifier is at least one of PVA, polyvinyl pyrrolidone or xanthan gum; the weight ratio of the ink to the powder material is 0.2-0.4; the precision improvement component includes PVA powder and cement clinker powder, and the mass ratio of the PVA powder to the cement clinker powder is 1:5-1:8; the solubilizing stabilizer is at least one of 2-pyrrolidone and sodium pyrrolidone carboxylate. Under the premise of realizing 3D printing, its mechanical indicators such as material strength, elastic modulus, density and brittleness can meet the similarity requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering geological models, and particularly relates to a bonded 3D printing similar material for complex geological models, which is used for simulating the mechanical properties of rock masses with different hardness properties and fabricating complex geological models. Background Art

[0002] A large number of fracture networks in geological structures seriously affect the safety of major infrastructure and energy projects and pose a threat to the safety of construction workers. Studying the catastrophe mechanism and failure characteristics of complex geological models is the basis for ensuring the safety of infrastructure and energy projects and guaranteeing the safety of construction workers. Physical model tests are an important research method for studying the catastrophe mechanism and failure characteristics of complex geological models in the field of geotechnical engineering. However, due to the coexistence of rock materials with various strengths and complex fractures in complex geological structures, there are currently few mature methods for fabricating three-dimensional physical models of complex geological structures.

[0003] The powder bonding 3D printing technology first lays a layer of powder on the printing platform, and then, according to the model information, selectively sprays an adhesive onto specific positions of the powder layer to harden it. By repeating the above process and stacking layer by layer, the required three-dimensional object can be obtained, providing a new way for the fine forming of complex geological models and enabling the printing of fine, complex, adjustable, and replicable complex geological models. In addition to meeting printability, the 3D printing material dedicated to geological models also needs to meet the similarity with rock materials, including the similarity of indicators such as density, elastic modulus, strength, and brittleness. This is the key and difficulty of 3D printing for geological models. Model tests generally adopt scale-down tests with a scale ratio of 1:100 - 1:50. After scaling down, the strength of the similar material also needs to be reduced in proportion, resulting in a relatively low strength (0.3 - 3 MPa) of the similar material. For the powder bonding 3D printing technology, methods such as reducing the amount of ink used or reducing the amount of cement used at a high ink usage are often adopted to prepare materials with low strength. However, with less ink, the penetration between layers is insufficient, and there is an obvious interlayer interface, making the 3D printed specimens have obvious inhomogeneity and ductility. When reducing the amount of cement used at a high ink usage, the setting time of the material becomes longer, and the ink diffuses severely in the powder material, reducing the forming accuracy. It is very difficult to prepare a powder bonding 3D printing similar material with low strength, homogeneity, brittleness, and similarity to rock. Therefore, up to now, there has been no report on powder bonding 3D printing rock similar materials.

[0004] There are some literature reports on printing materials dedicated to powder bonding 3D printing. For example, Chinese patent No. ZL201510101564.9 discloses a gypsum material for 3D printing and a preparation method thereof, using hemihydrate gypsum as the main powder. Although the 2-hour wet compressive strength is ≥20MPa, the printed gypsum specimens show obvious ductility and cannot simulate the brittleness of rock materials, and cannot be used for making rock-like models. The Chinese patent with the patent number ZL202110004608.1 discloses a material for a powder 3D printing test model and its preparation method. The powder material in the material used is composed of magnesium phosphate cement, PVA, mineral admixture components (fly ash or silica fume), fiber reinforcement components (carbon nanotubes) and quartz sand; the binder is composed of 1,2-propylene glycol, glycerol and water, and 1,2-propylene glycol and glycerol account for 3-8% of the total mass of the binder. PVA is used for the preparation of powder materials. Although the 7d compressive strength can reach the strength requirement of more than 10MPa and 3D printing can be achieved, the density and brittleness of the printed material cannot meet the requirements of rock similar materials. The similarity law is the theoretical basis of the physical model test of the geological model. Before conducting the physical model test, the similarity of the material must be considered, including the mechanical indicators such as material strength, elastic modulus, density and brittleness must meet the similarity before it can be used to simulate rock materials.

[0005] Based on the above problems, there is an urgent need to develop a material that meets rock similarity and can be used for powder bonding 3D printing. Summary of the invention

[0006] The purpose of the present invention is to provide a bonding type 3D printing similar material for complex geological models, which satisfies the mechanical properties similar to those of real rocks and can be used to make real complex geological models.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention discloses a bonding type 3D printing similar material for complex geological models, including powder material and ink.

[0009] The powder material comprises, by weight, 10 to 40 parts of dead-burned MgO, 5 to 30 parts of phosphate, 30 to 100 parts of barite powder, 8 to 25 parts of hemihydrate gypsum, and 50 to 100 parts of precision improvement components;

[0010] The ink comprises 3-10% viscosity modifier, 0.5-2.5% solubilizing stabilizer, 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% moisturizer, and 80-97% deionized water;

[0011] The viscosity modifier is at least one of PVA, polyvinyl pyrrolidone (PVP) or xanthan gum;

[0012] The weight ratio of the ink to the powder material is 0.2-0.4; the precision improvement components include PVA powder and cement clinker powder, and the mass ratio of the PVA powder to the cement clinker powder is 1:5-1:8;

[0013] The solubilization stabilizer is at least one of 2-pyrrolidone and sodium pyrrolidone carboxylate.

[0014] The surface tension modifier is a non-ionic surfactant, the defoaming agent is a silicone defoaming agent, and the pH of the defoaming agent is 3-14; the humectant is at least one of glycerol and 1,2-propanediol.

[0015] The viscosity of the ink is 3-15 mPa·s, and the surface tension is 35-55 mN / m.

[0016] The PVA powder is one or more of the models 17-80, 17-88, 17-92, and K30, with a purity greater than 98%, a molecular weight of 30,000-100,000, and a fineness of 150-200 mesh; the cement clinker powder is one or more of ordinary Portland cement clinker, sulphoaluminate cement clinker, and aluminate cement clinker, with a particle size of 0.045-0.125 mm.

[0017] The density of the hemihydrate gypsum is 2.6 g / cm 3 , with a purity greater than 98% and a particle size range of 0.075-0.125 mm; the bulk density of the barite powder is 3.2-3.8 g / cm 3 , with a particle size range of 0.075-0.15 mm;

[0018] The dead-burned MgO is obtained by calcining MgO material in a high-temperature furnace at 1600-1950 °C for 50-120 min, then ball-milling at 1500-1800 r / min for 15-35 min and sieving, with a bulk density of 1.8-2.0 g / cm 3 , a specific surface area of 230-287 m 2 / kg, and a particle size range of 0.075-0.15 mm;

[0019] The phosphate is one or more of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate powders, with a purity of the phosphate material above 92% and a maximum particle size of 0.125 mm.

[0020] The present invention also provides a preparation method of the similar material, and the method includes the following steps:

[0021] (1) Add 10 - 40 parts of dead-burned MgO, 5 - 30 parts of phosphate, and 30 - 100 parts of barite powder into a planetary mixer, and stir for 5 - 10 min until evenly mixed; then, add 8 - 25 parts of hemihydrate gypsum and 50 - 100 parts of precision improvement components, and continue to stir for 10 - 15 min until evenly mixed, thus obtaining the powder material described above;

[0022] (2) Add 3 - 10% viscosity modifier into 0.5 - 2.5% solubilization stabilizer, and stir for 10 - 15 min until evenly mixed;

[0023] (3) Add 0.1 - 0.8% surface tension modifier, 0.01 - 0.1% defoamer, 3 - 6% moisturizer, and 80 - 97% deionized water into the above solution, and ultrasonically disperse it with an ultrasonic disperser at a frequency of 50 Hz for 5 - 10 min;

[0024] (4) Vacuum filter the ink successively using PP material filter membranes with pore sizes of 15 μm, 10 μm, and 0.5 μm, and the vacuum filtration negative pressure is 0.7 - 0.8 MPa;

[0025] (5) Degas the filtered ink successively using a vacuum degassing tank and a vacuum degassing mold, thus obtaining the ink material;

[0026] (6) Add the above-prepared powder material into the powder material feeding bin of the printer, add the ink material into the first-level ink cartridge of the ink supply system, and perform printing through powder 3D printing technology. The layer thickness is 0.1 - 0.2 mm, and the printing speed is 600 - 800 mm / s. After printing, remove the unbonded powder and take out the model, place it in a curing film, and cure it indoors for 24 h to obtain a complex geological model that meets the test requirements.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The similar material of the present invention is a high-density and high-brittle material. The density of the similar material is above 2.4 g / cm 3 ³, and the ratio of the tensile strength to the compressive strength is above 15, having brittleness similar to that of rock. On the premise of realizing 3D printing, the similarity with the rock model is ensured, and the mechanical indexes such as material strength, elastic modulus, density, and brittleness can all meet the similarity requirements.

[0029] 2. In the powder material of the present invention, hemihydrate gypsum and barite powder are added as auxiliary components to the magnesium phosphate component, and a precision improvement component containing cement clinker powder is added. By using a high ink dosage (the weight ratio of ink to powder material is 0.2 - 0.4, while the conventional ink dosage is generally controlled such that the weight ratio of ink to powder material is not greater than 0.1), high homogeneity, high brittleness, high density, and high precision are achieved at low strength. The mechanical indexes such as elastic modulus, brittleness, and density of the printing material are similar to those of rock materials, meeting the printing precision requirements and overcoming the deficiency that the printed gypsum material in the existing formula has obvious ductility and cannot simulate rock materials.

[0030] 3. The precision improvement component in the present invention is composed of highly water-soluble PVA powder and cement clinker powder. The PVA powder can prevent the excessive diffusion of ink in the powder material and improve the forming precision. The cement clinker powder with an appropriate dosage reacts with MgO and phosphate, which can significantly improve the shrinkage and cracking problems caused by the rapid reaction of MgO and phosphate under a large ink volume, and can control the setting time within 1 minute, achieving rapid setting without significantly increasing the strength, improving the ink diffusion phenomenon, and further enhancing the forming precision of the material. Due to the specific formulation settings and particle size distribution of the dead-burned MgO, phosphate, barite powder, hemihydrate gypsum, and precision improvement component in the present invention, they can avoid agglomeration during powder printing and have good fluidity. The barite powder is processed by a circular grinding process, and the particles are round polygons, which are all beneficial to improving the spreading and packing density of the powder material;

[0031] 4. Since a large amount of ink needs to be printed to meet the homogeneity of the material, and in order to avoid the reduction of precision caused by the diffusion of a large amount of ink, a large amount of binder needs to be added to increase the ink viscosity. In addition to viscosity modifiers such as PVA, polyvinylpyrrolidone (PVP), or xanthan gum in the ink of the present invention, pyrrolidone-based solubilizing stabilizers are also added. The solubilizing stabilizers with appropriate dosages interact with PVA or PVP to prevent precipitation and nozzle clogging problems when the binder content is relatively high.

[0032] 5. Glycerol or 1,2 - propylene glycol is added as a humectant to the ink of the present invention, effectively avoiding the problem that the water in the ink evaporates rapidly and dries up to clog the nozzle. The ink formula in the present invention can ensure the mutual solubility stability with water, prevent the ink from mildewing and deteriorating, avoid bubble clogging of the nozzle, improve the ability of the ink to wet the nozzle and the permeability of the ink in the powder material, and improve the forming precision. The ink of the present invention has the characteristics of non-clogging the nozzle, non-intermittent spraying, non-burning the nozzle, non-deteriorating, non-atomizing, and high-precision spraying, meeting the requirements of powder 3D printing and obtaining a similar material model with better precision. Description of the Drawings

[0033] Figure 1The following are: a complex geological model is printed using the ratio of Example 1: (a) design drawing, (b) actual picture.

[0034] Figure 2 This is the cross-sectional view of the specimen printed using the ratio of Comparative Example 2, mainly examining the effect of cement clinker content on the accuracy.

[0035] Figure 3 : A cross-sectional view of a test piece printed using the ratio of Example 1. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with specific embodiments, but this is not intended to limit the scope of protection of this application. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0037] The present invention discloses a bonding type 3D printing similar material for complex geological models, comprising powder material and ink:

[0038] The powder material comprises, by weight, 10 to 40 parts of heavy-burned MgO, 5 to 30 parts of phosphate, 30 to 100 parts of barite powder, 8 to 25 parts of hemihydrate gypsum, and 50 to 100 parts of precision improvement components.

[0039] The ink is composed of 3-10% PVA, 0.5-2.5% solubilizing stabilizer, 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% moisturizing agent and 80-97% deionized water.

[0040] The weight ratio of the ink to the powder material is 0.2-0.4.

[0041] The dead-burned MgO is obtained by calcining the MgO material in a high-temperature furnace at 1600-1950°C for 50-120 minutes, then ball milling at a speed of 1500-1800 r / min for 15-35 minutes and then sieving. The bulk density is 1.8-2.0 g / cm 3 , with a specific surface area of 230-287m 2 / kg, the particle size range is 0.075-0.15mm. Particles below 0.075mm are easy to agglomerate, which is not conducive to the spreading of powder materials. In order to improve printing accuracy, the printing layer thickness is generally limited to less than 0.15mm. Particles above 0.15mm will destroy the structure of the printed layer.

[0042] The phosphate is one or more of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and sodium dihydrogen phosphate powders. The purity of the phosphate material is above 96%, the maximum particle size is 0.125 mm. The reaction rate of the material doped with ammonium dihydrogen phosphate is the fastest, and the reaction rate of the material doped with potassium dihydrogen phosphate is the slowest. In practice, the appropriate phosphate material needs to be selected according to the strength and precision requirements.

[0043] The particle morphology of the barite powder is a rounded polygon, which is obtained by grinding and screening barite. The rounded particle morphology can improve the fluidity and expandability of the material, which is beneficial to improving the spreading performance of the powder material. The bulk density of the barite powder is 3.2 - 3.8 g / cm 3 , the particle size range is 0.075 - 0.15 mm. The barite powder has a large density, which increases the density of the powder-packed material and makes the density of the printing material meet the similarity with the rock material.

[0044] The density of the hemihydrate gypsum is 2.6 g / cm 3 , the purity is greater than 98%, and the particle size range is 0.075 - 0.125 mm, which adjusts the brittleness of the material and makes the brittleness of the printing material meet the similarity with the rock material.

[0045] The precision improvement components include PVA powder and cement clinker powder, and the mass ratio of the two is 1:8 - 1:5; preferably, the PVA powder is one or more of the models 17 - 80, 17 - 88, 17 - 92, and K30, the purity is greater than 98%, the molecular weight is 30,000 - 100,000, and the fineness is 150 - 200 mesh.

[0046] The cement clinker powder is one or more of ordinary Portland cement clinker, sulphoaluminate cement clinker, and aluminate cement clinker, and the particle size is 0.045 - 0.125 mm.

[0047] Adding a certain amount of PVA powder to the powder material can prevent the excessive diffusion of ink in the powder material and improve the forming precision. At the same time, introducing cement clinker powder, the interaction between PVA powder and cement can effectively control the setting time of the magnesium phosphate system within 1 min, ensuring the dual requirements of strength and setting time, and at the same time reducing the shrinkage and warping problems caused by the rapid reaction of MgO and phosphate, and improving the forming precision of the material. If cement is selected instead of cement and plastic powder, the effective control of the required setting time cannot be achieved.

[0048] The solubilizing stabilizer is one of 2-pyrrolidone and sodium pyrrolidone carboxylate. In the ink, the viscosity modifier can interact with the pyrrolidone-based solubilizing stabilizer. On the premise of adding more viscosity modifiers, the dispersibility and uniform stability of the system can be ensured. It can not only improve the miscibility stability of the viscosity modifier and water, but also prevent the ink from mildewing and deteriorating. If other alcohols such as propanol and glycerol are selected, the solubilizing and stabilizing effects cannot be achieved in this system.

[0049] The surface tension modifier is a highly efficient non-ionic surfactant in a solution state. Its main function is to reduce the surface tension of deionized water, improve the ability of the ink to wet the nozzle, and the permeability of the ink in the powder material. The content of its active ingredient is greater than 99%. The defoamer is a silicone defoamer, and its main function is to eliminate the foam in the ink and prevent the nozzle from being blocked by the foam. The content of its active ingredient is greater than 98%, and the pH of the defoamer is 3-14. The humectant is one of glycerol and 1,2-propanediol, and its main function is to prevent the water in the ink from evaporating quickly and drying up to block the nozzle. The synergistic effect of several substances in the ink enables the ink to meet the requirements of a viscosity of 3-15 mPa·s and a surface tension of 35-55 mN / m, and has the characteristics of not blocking the nozzle, not burning the nozzle, not deteriorating, not atomizing, and high-precision printing.

[0050] The present invention also provides a preparation method of the similar material, and the method comprises the following steps:

[0051] (1) Add 10-40 parts of dead-burned MgO, 5-30 parts of phosphate, and 30-100 parts of barite powder to a planetary mixer, and stir for 5-10 min until evenly mixed; then, add 8-25 parts of hemihydrate gypsum and 50-100 parts of precision improvement components, and continue to stir for 10-15 min until evenly mixed to obtain the powder material;

[0052] (2) Add 3-10% PVA to 0.5-2.5% solubilizing stabilizer, and stir for 10-15 min until evenly mixed;

[0053] (3) Add 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% humectant, and 80-97% deionized water to the above solution, and ultrasonically disperse with an ultrasonic disperser at a frequency of 50 Hz for 5-10 min;

[0054] (4) Vacuum filter the ink successively with 15 μm, 10 μm, and 0.5 μm PP material filter membranes, and the vacuum filtration negative pressure is 0.7-0.8 MPa;

[0055] (5) Degas the filtered ink successively with a vacuum degassing tank and a vacuum degassing die to obtain the ink material;

[0056] (6) Add the prepared powder material to the powder material feeding bin of the printer, add the ink material to the first-level ink cartridge of the ink supply system, and perform printing through powder 3D printing technology. The layer thickness is 0.1 - 0.2 mm, and the printing speed is 600 - 800 mm / s. After printing, remove the unbonded powder and take out the model, place it in a curing film, and cure it indoors for 24 h to obtain a complex geological model that meets the test requirements.

[0057] Example 1

[0058] (1) Add 30 parts of calcined MgO, 15 parts of ammonium dihydrogen phosphate, and 80 parts of barite powder to a planetary mixer and stir for 10 min until evenly mixed; then, add 20 parts of hemihydrate gypsum and 90 parts of precision improvement components, and continue to stir for 10 min until evenly mixed to obtain the powder material. The calcined MgO is obtained by calcining MgO material in a high-temperature furnace at 1700 °C for 120 min, then ball milling for 30 min at a rotation speed of 1600 r / min and screening. Its bulk density is 1.8 g / cm 3 , and the specific surface area is 252 m 2 / kg, and the particle size range is 0.075 - 0.15 mm; the purity of ammonium dihydrogen phosphate is 96%, and the maximum particle size is 0.125 mm; the particle shape of barite powder is a rounded polygon, the bulk density is 3.5 g / cm3, and the particle size range is 0.075 - 0.15 mm. The density of hemihydrate gypsum is 2.6 g / cm 3 , the purity is greater than 98%, and the particle size range is 0.075 - 0.125 mm. The precision improvement components include 15 parts of PVA powder and 75 parts of sulphoaluminate cement clinker powder; the PVA powder is of K30 type, the purity is 98%, and the fineness is 200 mesh; the particle size of sulphoaluminate cement clinker is 0.045 - 0.125 mm.

[0059] (2) Add 8% PVA to 1.2% of 2-pyrrolidone and stir for 10 min until evenly mixed;

[0060] (3) Add 0.5% non-ionic surfactant Surfynol 465, 0.05% silicone defoamer, 4% of 1,2-propanediol, and 90% deionized water to the above solution and ultrasonically disperse it with an ultrasonic disperser at a frequency of 50 Hz for 8 min; the effective ingredient content of Surfynol465 is greater than 99%; the effective ingredient content of the silicone defoamer is greater than 98%, and pH = 3 - 14;

[0061] (4) Filter the ink successively through 15 μm, 10 μm, and 0.5 μm PP material filter membranes by vacuum filtration, and the filtration negative pressure is 0.7 MPa;

[0062] (5) The filtered ink is degassed successively using a vacuum degassing tank and a vacuum degassing mold to obtain the ink material. The prepared powder material is added to the powder material feeding bin of the printer, and the ink material is added to the first-level ink cartridge of the ink supply system. The weight ratio of the ink to the powder material is 0.3:1. Printing is carried out by powder 3D printing technology with a layer thickness of 0.15 mm and a printing speed of 600 mm / s. After printing, the unbonded powder is removed, and the model is taken out and placed in a curing film and cured indoors for 24 h to obtain a complex geological model that meets the test requirements.

[0063] Using this embodiment for 3D printing, a printed structure body is obtained. The printing process proceeds smoothly without cracking, and the integrity and accuracy of the printed structure are good. The geometric scale ratio between the model and the prototype is usually 1:50 or 1:25, and the scale ratios of density and Poisson's ratio are usually 1:1, so the scale ratios of compressive strength and elastic modulus are 1:50 or 1:25. The comparison with the physical indexes of rock mechanics is shown in Table 1, and the structure shows obvious brittle failure. It shows that this material is suitable for simulating the mechanical properties of hard rock materials at a scale ratio of 1:50. From Figure 1 As can be seen from the physical picture printed in it, this application can print a rock mass with a complex fracture shape, and the forming effect is good.

[0064] Example 2

[0065] Compared with Embodiment 1, the difference in this embodiment is that 30 parts of dead-burned MgO and 15 parts of ammonium dihydrogen phosphate are changed to "15 parts of dead-burned MgO and 15 parts of ammonium dihydrogen phosphate", 80 parts of barite powder are changed to 90 parts of barite powder, the mass ratio of the ink to the powder material is 0.25:1, and the 90 parts of precision improvement components include 10 parts of PVA powder and 80 parts of sulphoaluminate cement clinker powder. Using this embodiment for printing, a printed structure body is obtained. The printing process proceeds smoothly, and the integrity and accuracy of the printed structure are good, and brittle failure is obvious. The printing accuracy is good, and the minimum printable accuracy is 0.16 mm. Using this embodiment for 3D printing, a printed structure body is obtained. The printing process proceeds smoothly without cracking, and the integrity and accuracy of the printed structure are good. The comparison with the physical indexes of rock mechanics is shown in Table 2, and the structure shows obvious brittle failure. It shows that this material is suitable for simulating the mechanical properties of soft rock materials at a scale ratio of 1:50.

[0066] Example 3

[0067] This embodiment is different from Embodiment 1 in that 30 parts of dead-burned MgO and 15 parts of ammonium dihydrogen phosphate are changed to 40 parts of dead-burned MgO and 30 parts of ammonium dihydrogen phosphate. The mass ratio of the ink to the powder material is 0.35:1, and the 90 parts of the precision improvement component include 15 parts of PVA powder and 75 parts of sulfoaluminate cement clinker powder. Using this embodiment for printing, a printed structure body is obtained. The printing process proceeds smoothly, and the integrity and precision of the printed structure are good, and brittle failure is obvious. The printing precision is good, and the minimum printable precision is 0.2 mm. Using this embodiment for 3D printing, a printed structure body is obtained. The printing process proceeds smoothly, without cracking, and the integrity and precision of the printed structure are good. The comparison with the physical and mechanical indexes of rock is shown in Table 3, and the structure shows obvious brittle failure. It shows that this material is suitable for simulating the mechanical properties of hard rock materials at a scale of 1:25.

[0068] Example 4

[0069] This embodiment is different from Embodiment 1 in that 30 parts of dead-burned MgO and 15 parts of ammonium dihydrogen phosphate are changed to 30 parts of dead-burned MgO and 30 parts of ammonium dihydrogen phosphate, 80 parts of barite powder are changed to 90 parts of barite powder, the mass ratio of the ink to the powder material is 0.3:1, and the 90 parts of the precision improvement component include 10 parts of PVA powder and 80 parts of sulfoaluminate cement clinker powder. Using this embodiment for printing, a printed structure body is obtained. The printing process proceeds smoothly, and the integrity and precision of the printed structure are good, and brittle failure is obvious. The printing precision is good, and the minimum printable precision is 0.15 mm. Using this embodiment for 3D printing, a printed structure body is obtained. The printing process proceeds smoothly, without cracking, and the integrity and precision of the printed structure are good. The comparison with the physical and mechanical indexes of rock is shown in Table 4, and the structure shows obvious brittle failure. It shows that this material is suitable for simulating the mechanical properties of soft rock materials at a scale of 1:25.

[0070] Table 1

[0071]

[0072] Table 2

[0073]

[0074] Table 3

[0075]

[0076] Table 4

[0077]

[0078] Comparative Example 1

[0079] The preparation process of the printing material is the same as that of Example 1, except that: 90 parts of the precision improvement component in Example 1 is changed to 5 parts of PVA powder and 85 parts of sulfoaluminate cement clinker powder. During the test process, it was found that due to the insufficient amount of PVA powder in the comparative example, the penetration and diffusion of the ink in the powder material were relatively large, there were many defects in the specimen, and the precision was poor.

[0080] Comparative Example 2

[0081] The preparation process of the printing material is the same as that of Example 1, except that: 90 parts of the precision improvement component in Example 1 is changed to 30 parts of PVA powder and 50 parts of sulfoaluminate cement clinker powder. During the test process, it was found that due to the excessive amount of PVA powder in the comparative example, it was difficult for the ink to penetrate into the next layer in the powder material, resulting in obvious weak interfaces between layers and poor precision. Moreover, due to the small amount of sulfoaluminate cement clinker powder, the setting time was slower, the penetration and diffusion were relatively large, there were many defects in the specimen, and the precision was poor. In addition, as Figure 2 shown, due to the small amount of sulfoaluminate cement clinker powder, the specimen shrank and cracked severely.

[0082] Comparative Example 3

[0083] The preparation process of the printing material is the same as that of Example 1, except that: 8% PVA powder and 1.2% 2-pyrrolidone in the ink of Example 1 are changed to: 8% PVA and 0.4% 2-pyrrolidone. During the test process, it was found that due to the insufficient amount of 2-pyrrolidone in the comparative example, the solubility and stability of 8% high-dosage PVA powder in water became worse, obvious precipitation appeared in the ink, and the nozzle was blocked during the printing process.

[0084] Comparative Example 4

[0085] The preparation process of the printing material is the same as that of Example 1, except that: 8% PVA and 1.2% 2-pyrrolidone in the ink of Example 1 are changed to: 2% PVA powder and 0.5% 2-pyrrolidone. During the test process, it was found that although no precipitation occurred in the ink, due to the insufficient amount of PVA, the viscosity of the ink was insufficient, the ink penetrated and diffused severely in the powder, and the precision of the specimen was relatively poor.

[0086] Comparative Example 5

[0087] This comparative example is different from Example 1 in that 30 parts of dead-burned MgO and 15 parts of ammonium dihydrogen phosphate are changed to 50 parts of dead-burned MgO and 50 parts of ammonium dihydrogen phosphate. Using this example for printing, a printed structure body is obtained. The printing process proceeds smoothly, and the integrity and precision of the printed structure are good, and brittle failure is obvious. The comparison with the physical and mechanical indexes of rock is shown in Table 5, indicating that the material has relatively high compressive strength and elastic modulus and is not suitable for simulating the mechanical properties of rock materials.

[0088] Table 5

[0089]

[0090] Comparative Example 6

[0091] This example is different from Example 1 in that 80 parts of barite powder are changed to 20 parts of barite powder. Using this example for printing, a printed structure body is obtained. The printing process proceeds smoothly, and the integrity and precision of the printed structure are good, and brittle failure is obvious. The comparison with the physical and mechanical indexes of rock is shown in Table 6. The material has a relatively small density and is not suitable for simulating the mechanical properties of rock materials.

[0092] Table 6

[0093]

[0094] The materials of the present invention can be used to fabricate rock mass models with different hardness and softness properties and have the following characteristics: 1. The setting time of the materials is fast (5 - 10 minutes, and it can even be taken out just after printing); 2. The materials have typical brittle failure characteristics, and indexes such as strength, elastic modulus, Poisson's ratio and density satisfy similarity with rock materials, and can be used to fabricate complex geological models.

[0095] The preferred embodiments of this experiment have been described in detail above. However, this experiment is not limited to the specific details in the above embodiments. Additionally, it should be noted that among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, this experiment will not separately describe various possible combination methods.

[0096] Matters not described in the present invention are applicable to the prior art.

Claims

1. A bonding type 3D printing similar material for complex geological models, comprising powder material and ink, characterized in that: The powder material comprises, by weight, 10-40 parts of dead-burned MgO, 5-30 parts of phosphate, 30-100 parts of barite powder, 8-25 parts of hemihydrate gypsum, and 50-100 parts of precision improvement components; The ink comprises 3-10% viscosity modifier, 0.5-2.5% solubility stabilizer, 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% humectant, and 80-97% deionized water; The viscosity modifier is at least one of PVA, polyvinyl pyrrolidone or xanthan gum; The weight ratio of the ink to the powder material is 0.2-0.4; the precision improvement component includes PVA powder and cement clinker powder, and the mass ratio of the PVA powder to the cement clinker powder is 1:5-1:8; The dissolution stabilizer is at least one of 2-pyrrolidone and sodium pyrrolidone carboxylate.

2. The similar material according to claim 1, characterized in that, The surface tension modifier is a nonionic surfactant, the defoamer is an organosilicon defoamer, and the pH of the defoamer is 3-14; the humectant is at least one of glycerol and 1,2-propylene glycol.

3. The similar material according to claim 1, wherein The viscosity of the ink is 3-15 mPa.s, and the surface tension is 35-55 mN / m.

4. The similar material according to claim 1, characterized in that, The PVA powder has a purity greater than 98%, a molecular weight of 30,000-100,000, and a fineness of 150-200 meshes; the cement clinker powder is one or more of ordinary silicate cement clinker, sulphoaluminate cement clinker and aluminate cement clinker, and has a particle size of 0.045-0.125 mm.

5. The similar material according to claim 1, characterized in that, The density of the hemihydrate gypsum is 2.6 g / cm 3 , the purity is greater than 98%, and the particle size range is 0.075 - 0.125 mm; the bulk density of the barite powder is 3.2 - 3.8 g / cm 3 , and the particle size range is 0.075 - 0.15 mm; The re-burned MgO is obtained by calcining MgO material in a high-temperature furnace at 1600~1950 °C for 50~120 min, then ball-milling at a rotation speed of 1500 - 1800 r / min for 15 - 35 min and then screening. Its bulk density is 1.8 - 2.0 g / cm 3 , and its specific surface area is 230 - 287 m 2 / kg, and the particle size range is 0.075 - 0.15 mm; The phosphate is one or more of potassium dihydrogen phosphate, ammonium dihydrogen phosphate and sodium dihydrogen phosphate powder. The purity of the phosphate material is above 96%, and the maximum particle size is 0.125 mm.

6. The similar material according to claim 1, characterized in that, The similar material is a high-density and high-brittle material, and the density of the similar material is above 2.4 g / cm 3 Above, the ratio of the tensile strength to the compressive strength is above 15, and it has brittleness similar to the properties of rock.

7. A method for preparing the similar material according to claim 1, the method comprising the following steps: (1) 10-40 parts of dead-burned MgO, 5-30 parts of phosphate and 30-100 parts of barite powder are added to a planetary mixer and stirred for 5-10 minutes until the mixture is uniformly mixed; then, 8-25 parts of hemihydrate gypsum and 50-100 parts of precision improvement component are added and stirred for 10-15 minutes until the mixture is uniformly mixed, thereby obtaining the powder material; (2) Add 3-10% viscosity modifier to 0.5-2.5% solubilizing stabilizer and stir for 10-15 minutes until the mixture is uniform and a solution is formed; (3) adding 0.1-0.8% surface tension modifier, 0.01-0.1% defoamer, 3-6% humectant, and 80-97% deionized water to the above solution and dispersing the mixture using an ultrasonic disperser at a frequency of 50 Hz for 5-10 min; (4) The ink was vacuum filtered using 15 μm, 10 μm and 0.5 μm PP material filter membranes in sequence, with a vacuum pressure of 0.7-0.8 MPa; (5) Degassing the filtered ink using a vacuum degassing tank and a vacuum degassing mold in sequence to obtain an ink material; (6) Add the above-prepared powder material to the powder material feeding bin of the printer, add the ink material to the first-level ink cartridge of the ink supply system, and perform printing through powder 3D printing technology. The layer thickness is 0.1 - 0.2 mm, and the printing speed is 600 - 800 mm / s. After printing, remove the unbonded powder and take out the model, place it in a curing film, and cure it indoors for 24 hours to obtain a complex geological model that meets the test requirements.

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