Method for producing a three dimensional green article

Background of the invention 1. Technical field of invention The present invention relates to a method for producing a base product, particularly a method for producing a tertiary element base product.

Cross-reference of related applications This application claims the priority of Taiwan application number 101118038 filed on May 21, 2012.

2. Explanation of related technology Conventional methods for producing tertiary element features require a pressure sintering process (which requires high pressure), a powder injection molding method (which requires high pressure and the addition of a binder). ), And a casting molding method (a binder is used but no pressure is required). The step of applying pressure requires a machine to generate pressure and a mold with high pressure resistance. In contrast, the non-pressurized method simply requires a mold with low pressure resistance (eg, a plaster mold for casting).

In recent years, rapid prototyping technology has been developed. This feature is the production of 3D workpieces using the principle of deposition. In general, rapid prototyping techniques involve moving tools along a complex two-dimensional work path based on computer-stored layer-slicing data to form multiple layers, followed by layers. Includes steps to stack and interconnect to form a three-dimensional workpiece. The feature of such a technique is that it is possible to create a workpiece having an extremely complicated shape without using a mold. Since it does not require a mold, it is a manufacturing method that does not apply pressure. Therefore, a binder for binding the powder particles is required to form the substrate. A densification sintering step is then performed to produce a workpiece of desired strength.

In rapid prototyping technology, work paths include various tools (eg, nozzles for 3D printing (3DP) methods, extrusion heads for Fused Deposition Modeling (FDM) methods, and selective laser sintering (SLS) and stereo. It can be created using an energy beam for lithography (SLA) methods. Methods for producing tertiary element features using energy beams can be classified into additive methods and subtractive methods. The characteristic of the additive method is that a part of the base layer scanned by the energy beam is combined to form a part of the base product. Examples of additive methods include SLA, SLS and slurry-based selective laser sintering methods. A feature of the subtractive method is that a part of the substrate layer scanned by the energy beam is removed and the other part not scanned by the energy beam becomes a part of the substrate. Examples of subtractive methods include the thin film lamination (LOM) method, the computer-aided manufacturing (CAM-LEM) method of thin film lamination engineering materials, and the like.

See Figure 1. In US Patent Application Publication No. 2004/0075197, the applicant of the present invention discloses a method for producing the substrate 17. The above method is based on a slurry-based selective laser sintering method. (A) The step of mixing the ceramic powder, the solubilizer and the oxide sol together to form the slurry composition 11 and (B) A step of placing the slurry composition 11 on the platform 12 and moving the blade 13 along the horizontal direction (X) to smooth the slurry composition 11 on the platform 12 to form the slurry layer 14. (C) The slurry layer 14 is irradiated with the laser beam 15 along a predetermined plane (that is, two-dimensional) scanning path, and as a result, the oxide sol of the slurry layer 14 irradiated with the laser beam 15 is obtained. The step of gelling and bonding the ceramic powder to form the two-dimensional ceramic substrate layer 16 (D) Steps (B) and (C) are repeated a predetermined number of times to form a plurality of base layers 16, and then the base layers 16 are combined using a laser beam 15 to form a three-dimensional ceramic base product 17. Steps to form and (E) After step (D), the three-dimensional ceramic base material 17 is immersed in water 18 to dissolve the ungelled oxide sol to obtain the three-dimensional ceramic base material 17.

According to the method disclosed in US2004 / 0075197, the slurry layer 14 is irradiated along a predetermined planar (ie, two-dimensional) scanning path in step (C). In particular, it should be noted that the larger the volume of the finished ceramic substrate 17, the wider the scanning area defined by the planar scanning path. Therefore, the working time for forming the finished ceramic substrate 17 is expected to be relatively long.

From the above, it is preferable to reduce the production cost of the three-dimensional ceramic base product by reducing the working time for producing the three-dimensional ceramic base product. As a result, the technology for producing large workpieces is cost-effective.

When a 3D workpiece is produced by the subtractive method LOM or CAM-LEM, the working time is saved by scanning the linear contour of the workpiece with a laser. However, the LOM method disclosed in US 4,752,352 is suitable for producing 3D workpieces using, for example, paper, plastic, metal or ceramic materials. In contrast, the CAM-LEM method disclosed in US 5,779,833 is particularly suitable for producing inorganic substrates.

The CAM-LEM method comprises the step of producing a thin plate in an instrument (eg, a tape casting machine) and cutting the plate using a laser cutting instrument to make a cut-shaped workpiece. Next, the workpieces of the above plates are laminated by using a binder and then dried. Then, the stacking method is repeated to form a three-dimensional stack. Finally, the 3D stacks are compressed by pressing to bring the layers of the 3D stack into close contact with each other so that they can be bonded together in subsequent sintering methods. Therefore, the CAM-LEM method is complicated and requires work at various processing sites. In addition, multiple devices are also required in the CAM-LEM method.

The LOM method involves producing a sheet in an apparatus (eg, a tape casting machine), adhering the sheet to a workbench, and then cutting with a laser. The LOM method requires fewer equipment and processing sites, but it also requires laminating and joining thin plates. Good bonding between the sheets can affect the microstructure and sintering strength of the substrate.

According to US 5,779,833, the sheets are bonded by an adhesive layer placed between the sheets, or by using a solvent in which a binder is dissolved as an adhesive on the sheets, and then compressed and heated to ensure that the sheets are bonded. .. However, the adhesive layer is formed in the laminate thus made. Therefore, the microstructure of the substrate made from the laminate may not be uniform. In addition, the use of solvents does not change the composition of the substrate and does not require an adhesive layer, but requires a longer time for the binder to dissolve in a dry hard sheet steel and the bond strength should be properly controlled. I can't.

Since the thin plates cannot be brought into close contact with each other even by using the method described above, it is proposed in the CAM-LEM method that the stack of thin plates is further compressed. In this case, pressing and molding are required. In addition, it is well known to those skilled in the art that the stress gradient is caused by compression, resulting in non-uniform density. A more uniform density substrate can be obtained by hydrostatic press molding, but performing hydrostatic press molding can increase equipment costs. In addition, since hydrostatic press molding requires a mold, it is relatively inconvenient to provide a particular mold for workpieces with complex shapes or fine features. The solution to the problem is to form a simple square using a sacrificial material with a cross section that complements the workpiece. Therefore, the mold used in the compression step may have a simple square shape. After the compression process is performed, the sacrificial material and the workpiece can be separated from each other. However, in this method it is necessary to use a mold.

From the point of view of the CAM-LEM method described above, not only a large number of devices are required, but also molds for compression steps are required at a plurality of processing sites. Therefore, it is desirable to reduce the number of devices required and improve the adhesive strength of the sheet without performing compression steps and without the use of molds.

Disclosure of invention Therefore, an object of the present invention is to provide a method for producing a tertiary element feature that can solve the above-mentioned disadvantages related to the prior art.

According to the present invention, the method for producing a tertiary element feature is (a) A step of providing a slurry composition containing an inorganic powder, a binder and a solvent. (b) Steps to form a slurry layer made of the slurry composition, (c) A step of removing the solvent of the slurry layer from the upper surface of the slurry layer so as to form a base layer having a plurality of pores from the slurry layer. (d) The substrate layer is scanned along a predetermined linear first scanning path using an energy beam with sufficient power to vaporize or burn the binder, and the vaporized or burned binder is pored. The step of leaving the inorganic powder unbound by the binder while flowing out of the substrate through the (e) A step of repeating steps (b) to (d) to form a plurality of base layers by overlapping the base layers and sequentially scanning through a plurality of scanning steps is included. The holes are interconnected with the upper surface of the base layer and communicate with the fluid. The scanned portion of the substrate layer forms a first sacrificial region along the first scanning path, and the unscanned portion of the substrate layer is divided into a work part and a waste part. The work part and the waste part are methods that are separated by the first sacrificial area.

Other features and effects relating to the present invention will become apparent in the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

<figref num="1">FIG. 1 is a flow chart illustrating a method for producing an inorganic base product disclosed in US2004 / 0075197.</figref>

<figref num="2">FIG. 2 is a flow chart illustrating a preferred embodiment of the method for producing a tertiary element feature according to the present invention.</figref>

<figref num="3">FIG. 3 is a schematic perspective view illustrating a preferred embodiment of the scanning step, in which the energy beam is used to scan the substrate layer along a predetermined scanning path.</figref>

<figref num="4">FIG. 4 shows the permeation state of the solvent and the binder and the adhesion between the binder and the inorganic powder when the step of forming the slurry layer and the step of removing the solvent of the slurry layer of the method of the preferred embodiment are carried out. It is a flow chart which illustrates the relationship.</figref>

<figref num="5">FIG. 5 is a flow chart illustrating the relationship between the two first sacrificial regions formed in the first step and the later step.</figref>

<figref num="6">FIG. 6 illustrates the undesired decay event of the inorganic powder due to improper parameters used in the scanning step and the undesired structure of the substrate layer.</figref>

<figref num="7">FIG. 7 is a flow diagram illustrating the complete structure of the substrate layer produced when the appropriate parameters are used in the scanning steps of the method of the preferred embodiment.</figref>

<figref num="8">FIG. 8 is a diagram illustrating the relationship between several second sacrificial regions formed by a series of scanning steps.</figref>

Detailed description of preferred embodiments See Figures 2, 3 and 4. A preferred embodiment of the method for producing the tertiary element feature 5 of the present invention is (a) The step of providing the slurry composition 2 containing the inorganic powder 21, the binder 22 and the solvent 23, (b) The step of forming the slurry layer 20 made of the slurry composition 2 on the workbench, and (c) A step of removing the solvent of the slurry layer from the upper surface of the slurry layer so as to form a base layer having a plurality of pores from the slurry layer. (d) The substrate layer is scanned along a predetermined linear first scanning path using an energy beam with sufficient power to vaporize or burn the binder, and the vaporized or burned binder is pored. The step of leaving the inorganic powder unbound by the binder while flowing out of the substrate through the (e) A step of repeating steps (b) to (d) to form a plurality of base layers 3 by overlapping the base layers and sequentially scanning through a plurality of scanning steps is included. The holes are interconnected with the upper surface of the base layer and communicate with the fluid. The scanned portion of the substrate layer forms a first sacrificial region along the first scanning path, and the unscanned portion of the substrate layer is divided into a work part and a waste part. It is a method in which the work part and the waste part are separated by the first sacrifice area. Preferably, a preferred embodiment of the method of the invention further comprises step (f) after step (e) separating the workpiece 311 from the waste portion 312 along the first sacrificial region 301.

In the slurry composition 2, the combination of the binder 22 and the solvent 23 is hereinafter referred to as a liquid.

See Figure 4. In each of the steps (b) repeated in step (e), after the slurry layer 20 is spread, a part of the solvent 23 and a part of the binder 22 (that is, a part of the liquid) in the slurry layer 20 are the lower layer. Base layer 3 (depth d₁) Penetrates downward.

In each of the steps (c) repeated in step (e), the solvent 23 vaporizes upward to form pores that are interconnected and connected to the external environment. As the solvent evaporates in this step, the binder 22 that has penetrated into the underlying substrate 3 remains and binds to the inorganic powder 21 in the underlying substrate 3. At the same time, as the upper slurry layer 20 dries (ie, the solvent is removed), some of the binder 22 that has not penetrated downward binds to the inorganic powder 21 to form the upper substrate layer 3. .. The dry substrate layer 3 has a thickness (t). This is thinner than the slurry layer 20. In the present invention, the sum of d1 and t is the adhesive thickness (t)._b).

In this way, the upper base layer 3 and the lower base layer 3 form a seamless bond by the binder 22 that has penetrated into the lower base layer 3.

The penetration depth (d1) is clearly related to the amount of solvent in the slurry layer 20. A thick penetration thickness (d1) indicates a larger amount of solvent, resulting in longer drying times, which can cause unwanted gaps in the substrate layer 3. Conversely, a thin penetration thickness (d1) indicates a small amount of solvent. In such a case, the drying time can be shortened, but it may not be possible to make the formed base layer 3 a smooth surface. In general, the penetration thickness (d1) is in the range of 2 to 3 times the thickness (t) of the substrate layer 3. In principle, seamless bonding can be achieved when the penetration thickness (d1) is equal to the thickness (t) of the substrate layer 3. In such a case, the drying time can be shortened. Therefore, preferably, the permeation thickness (d1) is equal to the thickness (t) of the base layer 3.

See Figure 5. The base layer 3 (that is, the lowest layer of the base layer 3) formed in step (c) is the thickness (t).₀), And each of the base layers 3 formed in step (e) (see (ec) in FIG. 5) has a thickness (t). Then, each of the first sacrificial regions 301 formed by the method of the present invention is a depth (D) which is a depth from the upper surface of the corresponding layer in the base layer 3.₁). Depth (D₁) Can also be specified as the scanning depth of the laser beam. In the present invention, the depth (D₁) Is preferably larger than the thickness (t). Preferably, the laser scanning depth (D)₁) Is the bond thickness (t)_b Greater than or equal to its thickness = t + d1).

Since the binder 22 in the scanned portion (ie, the first sacrificial region 301) vaporizes or burns, the bond strength of the powder 21 is relatively higher than in the unscanned portion (ie, workpiece 311 and waste portion 312). It should be noted that it is weak. D1 is greater than t t_bIf less than, the permeated binder 22 is not completely removed, but the amount of permeated binder 22 in the scanned portion is even less than that in the unscanned portion. Therefore, the bond strength of the powder 21 in the scanned portion is weaker than that in the unscanned portion. D₁Is t_bIf greater than, the penetrating binder 22 in the scanned portion is completely removed and the bound strength of the scanned portion is relatively weak (almost no bond strength can be considered). These two situations are illustrated by the following examples.

Note that a thick base layer may be formed as the workbench may not be flat. This base layer is made from a ceramic composition containing an inorganic powder, a binder and a solvent. The inorganic powders, binders and solvents in the ceramic composition may be the same as or different from those in slurry composition 2.

The inorganic powder 21 used in a preferred embodiment of the present invention may be a ceramic powder or a metal powder. In one embodiment of the invention, the inorganic powder 21 is a ceramic powder made of yttria partially stabilized zirconia (YPSZ). The binder 22 and solvent 23 of the slurry composition 2 can be those commonly used in the field of substrates. In one embodiment of the invention, the binder is polyvinyl alcohol (PVA) and the solvent is water.

The energy beam 4 used in step (d) is a CO with a beam diameter typically ranging from 0.2 mm to 0.3 mm.₂It is a pulsed laser beam. Base layer 3 is CO₂When scanned by a pulsed laser beam, the laser scanning speed and laser output can remove the binder 22 in the substrate layer 3 while leaving the inorganic powder 21 unbound by the binder 22 in its original position. Must be controlled.

Since the first scanning path 41 used in the scanning step (d) performed later overlaps with the first scanning path 41 used in the scanning step (d) performed earlier, the step (d) performed earlier and the step (d) performed later The first sacrificial regions 301 formed in step (d) performed overlap with each other.

In the first sacrificial region 301 formed in each of the repeated steps (d), the binder 22 of each base layer 3 is removed, and the inorganic powder 21 of each base layer 3 scanned by the energy beam 4 is the same. It remains in its original position. Therefore, the slurry layer 20 in each of the repeated steps (b) can be used as a support for the slurry layer 20 formed on the slurry layer 20. As a result, the inorganic powder 21 of the base layer 3 can be efficiently and uniformly formed on the base layer 3 of the lower layer.

In the slurry composition 2, the binder 22 is preferably present in an amount of 10 to 30% by volume based on the volume of the inorganic powder 21. The solvent 23 adds the binder 22 of the slurry layer 20 to the underlying layer 3 of the lower layer (d).₁) Is present in sufficient quantity to bring. As mentioned above, preferably d₁Is equal to t.

As shown in FIG. 6, in scanning step (d), the inorganic powder 21 will disintegrate if the laser scanning speed and laser power are not properly controlled. As a result, a groove 303 is formed in the scanned first sacrificial region 301 as shown in FIG. 6-1. After that, as shown in FIG. 6-2, the slurry layer 20 composed of the inorganic powder 21, the binder 22, and the solvent 23 is added to the base layer 3 having the groove 303, and flows into the groove 303. As shown in FIG. 6-3, after the solvent 23 is removed, an uneven surface is obtained. Therefore, the shape of the substrate 5 may be undesirably affected. Further, the material filling the groove 303 includes a portion of the binder 22 that is not the desired material for the first sacrificial region 301 of the present invention. Therefore, the resulting first sacrificial region 301 is uneven and difficult to remove due to the presence of the binder 22. Further, as shown in FIG. 2 (e), when producing the base product 5 having an inclination, in addition to the first sacrificial region 301 in the lower base layer 3, one of the upper slurry layers 20 supported by the first sacrificial region 301. The part forms the work part 311 (ie, part of the substrate 5). Therefore, when the inorganic powder 21 collapses to form the groove 303, a suitable support is not provided to the upper slurry layer 20 and the work portion 311 cannot be completely formed.

In the conventional method, the groove 303 can be filled with the sacrificial material to support the upper slurry layer 20, but such a step requires working time, additional cost for the sacrificial material and the tool for filling the groove 303 with the sacrificial material. Not only that, but also an accurate technique for filling the small groove 303 with sacrificial material is required. Conversely, the method of the present invention does not require such additional steps because the laser conditions are well controlled and the inorganic powder 21 is kept in its original position. Therefore, the present invention provides a simple but effective solution.

FIG. 7 illustrates the complete structure of the first sacrificial region 301. It is produced when the appropriate parameters are used in the scanning step in the method of the preferred embodiment. FIG. 7-1 is a cross-sectional view of the first sacrificial region 301 of the present invention. When the additional slurry layer 20 is added to the first sacrificial region 301, as shown in FIG. 7-2, a part of the solvent 23 in the upper slurry layer 20 carries a part of the binder 22 and the lower base layer. All of the inorganic powder 21, the residual binder 22, and the residual solvent 23 remain in the upper slurry layer 20 while penetrating the pores of the first sacrificial region 301 in 3. After removing the solvent 23, the binder 22 binds to the inorganic powder 21 in the upper layer and the inorganic powder 21 in the first sacrificial region 301 in the base layer 3 in the lower layer (see FIG. 7-3). Since the first sacrificial region 301 in the lower substrate layer 3 functions as a support in this preferred embodiment, the upper slurry layer 20 can be uniformly spread. Since the generated base layer 3 is also uniformly formed, it is possible to obtain a complete base product 5.

As shown in FIG. 7-3, in the present invention, the permeation of the binder 22 and the solvent 23 in the upper slurry layer 20 is controlled. As a result, the first sacrificial region 301 (shown in FIG. 7-1) formed in the previously performed scanning step (d) is completely squeezed by the binder 22 and solvent 23 penetrating downward from the upper slurry layer 20. Is not satisfied. Further, in order to continuously connect the first sacrificial region 301, the first scanning path 41 used in the scanning step (d) executed later is the first scanning path 41 used in the scanning step (d) executed earlier. Depth (D), apart from the condition that it should overlap with₁) Is the bond thickness (t)_bIt should be the same as or larger than = t + d1). If d1 is equal to t, then D₁Is equal to or greater than 2t.

As shown in FIG. 2 (e), based on the specific design conditions described above, the continuously connected first sacrificial region 301 causes the waste portion 312 and the work portion 311 in the unscanned portion 31 of the substrate layer 3 to be , Can be separated along the overlapping first sacrificial region 301 to obtain the tertiary element feature 5.

See FIGS. 3 and 8. In a preferred embodiment of the invention, step (d) is a substrate layer along a predetermined linear second scanning path 42 by an energy beam 4 having a scanning rate and appropriate power for vaporizing or burning the binder 22. The waste portion 312 in the unscanned portion 31 of 3 is scanned, whereby the vaporized binder 22 or the burned binder 22 flows out of the substrate layer 3 through the pores, while the inorganic powder 21 not bound to the binder 22. Includes a step of leaving to form a second sacrificial region 302. The second scanning path 42 used in the scanning step executed later overlaps with the second scanning path 42 used in the scanning step executed earlier. In one embodiment of the present invention, the second scan path 42 used in the later scan step is completely parallel to the second scan path 42 used in the earlier scan step. Each of the second sacrificial regions 302 formed in each of the repeated steps (d) is the depth (D) from the top surface of the corresponding layer of the base layer 3.₂). Depth (D₂) Is preferably larger than the thickness (t). As mentioned above, to overlap two adjacent second sacrificial regions 302, D₂Is the bond thickness (t_bIt is preferably equal to or greater than = t + d1).

The inorganic powder 21 preferably has an average particle size equal to or smaller than 1 μm. In this way, a higher capillary force is generated between the particles of the inorganic powder 21 to ensure that the particles of the inorganic powder 21 are in contact with each other.

The feature of the present invention is that the solvent 23 carries the binder 22 and permeates into the lower base layer 3, and as a result, the binder 22 binds to the lower base layer 3 so that the binder 22 is adjacent to the base layer 3. The two layers of are seamlessly connected. However, if the binder 22 and solvent 23 penetrate too deeply, their removal becomes more difficult. On the other hand, the first and second sacrificial regions 301 and 302 of the lower layer may be completely refilled with the binder 22 and the solvent 23. That is, the characteristics of the first and second sacrificial regions 301 and 302 of the lower layer, which were initially simply composed of the inorganic powder, are the characteristics of the unscanned portion of the base layer (that is, the portion composed of the inorganic powder and the binder). become. This results in the disappearance of the first and second sacrificial areas 301 and 302. Therefore, the structure of the first sacrificial region 301 connected continuously and the structure of the second sacrificial region 302 connected continuously will not be obtained, and the substrate 5 having the expected shape will not be obtained.

Furthermore, as mentioned above, the laser scanning depth (D)₁) Is t_bIt is preferable if it is the same as or larger than that. t_bIf is too large, the scan time needs to be longer and the laser output needs to be higher. Therefore, as long as the slurry layer 20 can be spread uniformly, the liquid content in the slurry layer 20 should be as small as possible.

Preferred bond thickness (t)_b) Is 2t. That is, d1 is equal to t. The following equation (a) can be used to obtain the liquid content when d1 is equal to t.

<maths num="1"><img id="000002" he="13" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

Using equation (a), the volume relationship in the case of the slurry layer 20 spread over the unscanned portion will be described (see FIG. 4). V_bAnd V_sIs the volume of the binder 22 and the solvent 23 of each slurry layer 20, respectively. And Vv is the interstitial volume of the base layer 3 after removing the binder 22.

The left side of equation (a) (representing the volume of permeated liquid, equal to the total liquid volume minus the interstitial volume (Vv)) removed solvent 23 (binder 22 still remained). The volume of holes (V) that will later be formed in the underlying substrate layer 3_aIt should be noted that it is equal to the right side of the equation (a) representing).

Binder volume (V_b) And the volume of the gap (Vv), the volume of the solvent (V)_s) Can be calculated based on the equation (a).

Equation (a) is obtained by the following mathematical method.

When the volume of the base layer 3 is 100 and the gap of the base layer 3 after vaporization of the binder 22 is 50% by volume (that is, Vv is 50), the volume of the inorganic powder (V)._p) Is 50. In the slurry composition 2, when the binder 22 is 30% by volume based on the volume of the inorganic powder 21, V_bShould be 15. In addition, the solvent (V_sThe unknown volume of) is set to X.

From the above, the volume of the slurry layer 20 is V._p+ V_b+ V_s= (50 + 15 + X) and the volume of the liquid (ie solvent and binder) is V_b+ V_s(That is, (15 + X)). After the slurry layer 20 is added onto the underlying substrate layer 3, part of the liquid remains in the slurry layer 20 and the remaining liquid permeates downward. Since Vv is 50, the volume of liquid remaining in the upper slurry layer 20 is 50 (that is, the same as Vv), and the volume of liquid penetrating into the lower base layer 3 is V._b+ V_s-Vv (ie, 15 + X-50 = X-35). The volume ratio of the binder 22 in the liquid is as follows.

<maths num="2"><img id="000003" he="13" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

Therefore, after the solvent 23 is removed from the liquid that remains in the upper slurry layer 20, the volume of the binder 22 in the upper substrate layer 3 is as follows.<maths num="3"><img id="000004" he="13" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>Then, the volume of the holes in the upper base layer 3 (V)_a) Is as follows.<maths num="4"><img id="000005" he="14" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

After the solvent 23 is removed from the liquid that has penetrated downward into the underlying substrate layer 3, the volume of the binder 22 in the underlying substrate layer 3 is as follows.<maths num="5"><img id="000006" he="13" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

When another slurry layer 20 having the above-mentioned slurry composition 2 is further added, the volume of the liquid penetrating downward into the underlying substrate layer 3 is X-35 (ie, V)._b+ V_s-V_v), And the volume of the liquid (ie, (X-35)) is the volume V of the holes in the underlying stratum 3_a(That is,<img id="000007" he="12" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" />) Should be the same. Therefore, equation (a) is obtained in this way. V_bAnd V_vBy substituting the value of into equation (a), the resulting equation is as follows, and the resulting volume (X) of solvent 23 is 77.

<maths num="7"><img id="000008" he="11" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

The above-mentioned volume is calculated based on 100 parts by volume of the base layer 3. With respect to the volume percent of slurry composition 2, slurry composition 2 contains 35.21% by volume of inorganic powder 21, 10.56% by volume of binder 22 and 54.23% by volume of solvent 23.

With respect to the slurry composition 2 described above, after the solvent 23 was removed, the substrate layer 3 formed by the top slurry layer 20 had 50% by volume of inorganic powder 21, 8.15% by volume of binder 22 and 41.85. Includes% by volume holes. The gap volume is equal to 50% by volume because it is equal to the sum of the binder volume and the pore volume. Since d1 is equal to t, the volume percentage of the permeated liquid should be 41.85%. The volume ratio of the binder 22 in the slurry composition 2 is 0.163 (10.56 volume% / (10.56 volume% + 54.23 volume%)). As a result, the percentage by volume of the permeated binder is 6.82% by volume (41.85% X 0.163). Therefore, the total volume percentage of the binder 22 in the lower base layer 3 is about 15% (6.819% + 8.15%), the volume percentage of the inorganic powder 21 is 50% by volume, and the volume fraction of the pores is 35% by volume. As a result, by using the slurry composition 2 described above, the uppermost layer of the base layer 3 in the unscanned portion has 8.15% by volume of the binder 22 and the lower base layer 3 in the unscanned portion. Each of them has a binder 22 of 15% by volume.

The volume percent of the binder 22 in the scanned portion of the substrate layer 3 can be calculated as follows with reference to FIG.

It should be noted that the same slurry composition 2 calculated as described above and added to the unscanned portion is used to calculate the volume percent of binder 22 in the scanned portion.

When the slurry layer 20 described above is also spread over the scanned portions (that is, the first and second sacrificial regions 301 and 302), the same amount of liquid permeates the underlying substrate layer 3. It is 41.85% by volume (V)_b+ V_s-Vv = 15 + 76.8-50 = 41.8). The content of binder 22 in the permeated liquid is 6.82% by volume (41.85% X 0.163). The same amount of liquid remains in the added slurry layer 20. That would be 50% by volume. Therefore, the upper substrate layer 3 in the scanned portion contains 8.15% by volume of binder 22 (50% X 0.163).

Laser scanning depth (D₁) Is equal to the thickness (t), the binder 22 in the sacrificial regions 301, 302 of the base layer 3 just spread is completely removed and the content of the binder 22 is zero. 6.82% of the binder still remains in the sacrificial regions 301 and 302 of the lower stratum 3 that the laser has not reached. Thus, after completion of the above method, each of the sacrificial regions 301, 302 has 6.82% binder 22 and the workpiece 311 has 15% binder 22. The content of each of the sacrificial regions 301 and 302 of the binder 22 is about 45.5% of the binder 22 content in the work portion 311. The bond strength of each of the sacrificial areas 301 and 302 is about 45.5% of that of the work piece 311.

Laser scanning depth (D₁) Is equal to 2t, the binder 22 in the sacrificial regions 301 and 302 of the upper and lower strata 3 is completely removed. Therefore, the sacrificial areas 301 and 302 do not contain binder 22, but both the work portion 311 and the waste portion 312 contain 15% binder 22. In such a situation, the work portion 311 can be easily separated from the waste portion 312 via the first sacrifice region 301 due to the weak bond strength of the first sacrifice region 301.

Based on the above, the sacrificial regions 301, 302 have a relatively low content of binder 22 due to laser scanning, and the laser scanning depth (D).₁) Deepens, the content of binder 22 decreases.

In view of the above, the method of the present invention has the following features. 1. The method of the present invention, that is, the method of forming the slurry layer 20, removing the solvent 23, and scanning the substrate layer 3 can be performed in one apparatus. Therefore, the space occupied by the device used in the method of the present invention is much smaller than that of the device used in the LOM method and the CAM-LEM method. 2. In the present invention, the first scan path is a linear contour in the workpiece, which saves time compared to the plane scan used in the prior art (eg, US Application Publication No. 2004/0075197). 3. The present invention provides a good seamless bond between the substrate layers 3 and can be used to produce a complex shaped substrate 5 without performing a mold-based compression step. 4. A plurality of pores are formed in the base layer 3, and the vaporized or burned binder can be successfully discharged from the base layer 3 without damaging the base layer 3. Five. The sacrificial region 301 in each of the substrate layers 3 is merely composed of the inorganic powder 21 without the binder 22 and can be used as a support for the upper slurry layer 20. Therefore, the slurry layer 20 having a uniform surface can be obtained, and the substrate product 5 can be smoothed.

&lt;Example&gt; Examples of the method for producing the tertiary element feature 5 according to the present invention are shown below.

In the examples, the inorganic powder 21, the binder 22, and the solvent 23 were YPSZ powder, polyvinyl alcohol (PVA), and deionized water, respectively. Two types of slurry compositions (ie, the basic ceramic slurry composition and the workpiece ceramic slurry composition 2 which is the material for the base product 5 of the present invention) were prepared. Basic ceramics

<tables num="1"><img id="000009" he="27" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>^※Commercially available from EE-Tec, Inc.^#Commercially available from Dai-ichi Kogyo Seiyaku Co., Ltd. (Japan)^¥Commercially available from ChangChun Group (model number BF-24)

Table 2 shows the components of the geographic ceramic slurry composition 2, the amounts of the components, and the order of addition. The average particle size of YPSZ powder is about 0.2 μm. The pH value of the geographic ceramic slurry composition 2 is about 10.

A relatively large amount of water was required to prepare the geographic ceramic slurry composition 2 using the components shown in Table 2. However, large amounts of water allow the binder 21 of the workpiece ceramic slurry composition 2 to penetrate excessively to an undesired depth. Therefore, after the preparation of the geographic ceramic slurry composition 2 was completed based on the above equation (a), it was stirred at 50 ° C. to remove excess water.

<tables num="2"><img id="000010" he="63" wi="159" file="JP5714552B2_D0001.tif" img-format="tif" img-content="drawing" /></tables>Commercially available from &amp; SHIN-ETSU Chemical Co. Ltd.

The basic ceramic slurry composition was added to the workbench to form a base layer with a thickness of approximately 150 μm, followed by removal of deionized water in the base layer at 50 ° C. using a planar heater.

Next, the geographic ceramic slurry composition 2 is added to the base layer to form the geographic ceramic slurry layer 20, and then the deionized water in the geographic ceramic slurry layer 20 is poured at 50 ° C. using a flat heater. Removed. Then an additional workpiece ceramic slurry composition 2 is added to make 75 μm (ie, t).₀) Work piece Deionized water was removed until the ceramic base layer 3 was obtained. When the geographic ceramic slurry composition 2 is further added to the 75 μm geographic ceramic substrate layer 3 (ie, the underlying geographic ceramic substrate layer 3), part of the deionized water and part of the PVA is part of the underlying geographic ceramic. It penetrated into the substrate layer 3. Its depth was about 25 μm, which was equal to the thickness (t) of the geographic ceramic base layer 3 formed in the next step. After heating, as the deionized water was vaporized, an upper workpiece ceramic substrate layer 3 having a plurality of holes for fluid communication with the external environment was obtained. After removal of the deionized water, the YPSZ powder in the upper workpiece ceramic base layer 3 and the lower workpiece ceramic base layer 3 binds to PVA. Therefore, permeation of PVA and deionized water and vaporization of deionized water constitute a very important feature of the present invention. That is, the distribution of PVA can be controlled by the permeation of PVA and deionized water and the vaporization of deionized water. As such, the geographic ceramic substrate 3 can fluidly communicate with the external environment through the holes for seamless bonding between the geographic ceramic substrates 3, and the vaporized binder 22 can easily escape.

Next, CO of the workpiece ceramic base layer 3 with a scanning speed of 25 mm / sec and an output of 1.3 W.₂The PVA was vaporized by scanning twice along a predetermined linear first scanning path 41 with the pulsed laser beam 4. As a result, the vaporized PVA flows out of the geographic ceramic substrate 3 through the holes, while leaving the YPSZ powder unbonded by the PVA in its original position. The YPSZ powder not bound by PVA was used as a support for the subsequently added workpiece ceramic slurry composition 2. The scanned portion of the geographic ceramic base layer 3 forms the first sacrificial region 301 along the first scanning path 41, and the unscanned portion of the base layer 3 is divided into a work portion 311 and a waste portion 312. Each is separated by a first sacrificial region 301. The first sacrificial region 301 is a depth of 55 μm (D), which is the depth from the upper surface of the geographic ceramic base layer 3.₁) (That is, D₁&gt; 2t).

The discarded portion 312 is then subjected to CO with the same laser output and scanning speed as above.₂The pulsed laser beam 4 was scanned along a plurality of predetermined linear second scan paths 42 to vaporize the PVA. As a result, the vaporized PVA flowed out of the geographic ceramic substrate 3 through the holes, while leaving YPSZ powder unbonded by the PVA to form multiple second sacrificial regions 302.

After the scanning step is completed, the step of forming the workpiece ceramic slurry layer 20 and the step of removing the deionized water, and the CO₂The procedure including the step of scanning with the pulsed laser beam 4 was repeated 400 times. At that time, the first scanning path 41 used in the scanning step executed later overlaps with the first scanning path 41 used in the scanning step executed earlier. Further, the second scanning path 42 used in the scanning step executed later was made completely parallel to the second scanning path 42 used in the scanning step executed earlier in the top-bottom direction.

CO₂The function of the pulsed laser beam 4 is to heat the surface of the geographic ceramic base layer 3 to a high temperature and transfer the heat downward from the surface to vaporize the PVA in the geographic ceramic base layer 3, and sacrifice the first and second. Note that it forms regions 301, 302. Therefore, the depths of the first and second sacrificial regions 301 and 302 in the geographic ceramic base layer 3 are determined by the laser output and the scanning speed. Generally, if the amount of vaporized gas per unit time is larger, the YPSZ powder explosion phenomenon causes the YPSZ powder structure to be damaged more easily. Therefore, multiple scans are required if a deeper thickness is desired for the first and second sacrificial regions 301, 302. For this reason, in the embodiments of the present invention, each scanning step scanned the workpiece ceramic substrate layer 3 twice to achieve the desired depths of the first and second sacrificial regions 301, 302. .. If smoke is produced during the procedure, it indicates vaporization of PVA. Show that in the absence of the explosion, the YPSZ powder remains in its original position and in subsequent steps the uniform workpiece ceramic slurry layer 20 can be smoothly added to the underlying workpiece ceramic substrate layer 3. There is.

Finally, the work portion 311 is separated from the waste portion 312 of the work ceramic base layer 3 to form a three-dimensional ceramic (zirconium oxide) base product 5. The PVA in the ceramic substrate 5 can be heated in a furnace at 600 ° C. for 1 hour to burn completely, and the ceramic substrate 5 is fired to form a ceramic workpiece with increased mechanical strength. It should be further noted that the furnace may be further sintered.

The degree of densification of the ceramic substrate 5 and the ceramic workpiece is 46.31% and 99.46%, respectively. According to the three-point bending test (ASTM C 1161), the average strength of sintered ceramic workpieces reaches 923.3 MPa. From this, it is clarified that, unlike the CAM-LEM method in which pressure must be applied, in the method of the present invention, the ceramic substrate 5 having a uniform density can be formed by thin lamination of PVA and laser combustion. In addition, after sintering the ceramic substrate 5, a high density ceramic workpiece is obtained.

In summary, in the method of producing the tertiary element feature 5 of the present invention, the substrate layer 3 is bound to form a first sacrificial region 301 composed of the inorganic powder 21 which is not bound to the binder 22. It is scanned along the first predetermined linear scanning path 41 by an energy beam 4 having an output sufficient to vaporize the agent 22. Compared to conventional methods that use planar (ie, two-dimensional) scanning paths, the method of the present invention can reduce scanning time and is advantageous for producing large workpieces. Further, unlike the CAM-LEM method, in the method of the present invention, the ceramic substrate 5 having a uniform density can be obtained without applying pressure. In addition, the high density ceramic workpiece can be obtained after sintering the ceramic substrate 5.

While the present invention describes what is considered to be the most practical and preferred embodiment, the invention is not limited to the disclosed embodiments and is within the broadest interpretation and equivalent modifications. It is understood to be intended to include the various modifications contained in.