JP7279883B2 - A method for manufacturing a glass bulk body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a glass bulk body, and more specifically to a method for producing a glass bulk body capable of vitrifying an arbitrary region on the surface of aggregates of sand grains, rocks or concrete.

Since the laser beam has no mass, laser processing can be performed basically without noise and vibration, and not only processing and welding of metal materials, but also processing of concrete materials is attracting attention, and it is used in the construction field. Investigation into the applicability of

Specifically, it has been reported that when concrete or rock containing silica components is irradiated with a laser, the silica components in the irradiated area melt and vitrify. Drilling into the material, surface treatment, etc. are being studied.

For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 6-80485), a surface adhesion material containing an inorganic substance as a main component is placed on the surface of a building material base material, and the surface layer is melted by irradiating with a laser. , a surface treatment method for obtaining a building material with a strong film formed thereon has been proposed.

In the laser welding apparatus described in Patent Document 1, both the building material base material and the surface adhering material are melted, so that a strong cured film can be created, and a colored cured film can be formed on the surface of the construction material. It is said that it can be easily formed, and that the surface of construction materials can have heat and sound insulation effects.

Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 11-19785), a hardened cement body is irradiated with a laser to form a brittle layer in which the strength of the hardened cement body is reduced, and then the brittle layer is removed. A method for perforating a hardened cement body has been proposed.

In the method for perforating a hardened cement body described in Patent Document 2, a low-noise, low-vibration device is used to form a brittle layer with sufficiently reduced strength in the hardened cement body to be drilled, and then the brittle layer is formed. To remove the layer, a slow rotating mechanical or manual tool can be used to remove the fragile layer. As a result, the generation of vibration and noise during drilling can be suppressed as much as possible, and the working environment and surrounding environment during drilling can be improved.

JP-A-6-80485 JP-A-11-19785

However, in the construction material and the surface treatment method thereof described in Patent Document 1, it is essential to use a surface adhering material whose main component is an inorganic substance whose components have been adjusted for laser irradiation. The surface adhering material is melted by irradiation and coated on the surface of the building material base material. That is, the surface treatment method described in Patent Document 1 is a method of covering an inorganic substance using laser irradiation, and uses silica (SiO ₂ ) components contained in aggregates of sand grains, rocks, or concrete as raw materials, and any of these It is completely different from the method of manufacturing a glass bulk body in which a glass layer is formed in the region of .

The method for perforating the hardened cement body described in Patent Document 2 uses laser irradiation to form a brittle layer in the hardened cement body. This technique has a completely opposite directionality to the method of forming regions. Furthermore, formation of the frangible layer is limited to a narrow region corresponding to the perforation region, and there is no need to form the frangible layer continuously. That is, in the known prior art, aggregates of sand grains, rocks, or silica (SiO ₂ ) components contained in concrete are used as raw materials, and a dense glass layer is continuously formed in any region (especially in a wide region) of these. There is no way to make it form.

In view of the problems in the prior art as described above, an object of the present invention is to irradiate an aggregate of sand grains, rocks, or concrete with a laser, and to extract silica (SiO _{2 )} contained in these aggregates of sand grains, rocks, or concrete. ) is used as a raw material to provide a simple method for producing a glass bulk body in which a dense glass layer is continuously formed in an arbitrary region (especially in a wide region). Another object of the present invention is to provide a glass bulk body in which the surface of a substrate made of an aggregate of sand grains, rocks or concrete is vitrified and a glass layer is continuously formed in an arbitrary region.

In order to achieve the above object, the present inventors conducted intensive research on a laser irradiation method capable of forming a dense glass layer continuously and over a wide area. The inventors have found that it is extremely important to continuously extend the melted portion by laser scanning after forming the , and have arrived at the present invention.

That is, the present invention
A method for producing a glass bulk body by vitrifying the surface of an aggregate of sand grains, rocks or concrete, comprising:
the aggregate of sand grains, the rock and the concrete contain a silica (SiO ₂ ) component,
a first step of irradiating the surface with a laser at a fixed point to form a melted portion;
a second step of moving the irradiation position of the laser at a scanning speed at which the melted portion continuously expands to form a glass layer;
Continuously performing the first step and the second step;
To provide a method for manufacturing a glass bulk body characterized by:

By irradiating the surface of an aggregate of sand grains containing a silica (SiO ₂ ) component, rock, or concrete with a laser at a fixed point, it is possible to form a melted portion that serves as a seed for a glass layer. After that, by scanning the laser in any direction, the fusion zone can be expanded. Here, if the scanning speed is too fast, the melted portion will be divided or narrowed, and a dense glass layer cannot be formed continuously. On the other hand, if the scanning speed is too slow, vaporization of the silica (SiO ₂ ) component necessary for forming the glass layer, steam explosion, aggregates of sand grains that are the base material, changes in the shape of the rock or concrete, etc., may cause the formation of a dense layer. A glass layer cannot be formed continuously.

In the method for producing a glass bulk body of the present invention, it is preferable that powder containing a silica (SiO ₂ ) component is arranged on the surface as a preliminary treatment step of the first step. By supplying the silica (SiO ₂ ) component from powder in addition to the silica (SiO ₂ ) component contained in aggregates of sand grains, rocks, or concrete, the glass layer can be formed more stably and efficiently. can.

Further, in the method for producing a glass bulk body of the present invention, it is preferable that the glass layer is subjected to the preliminary treatment step, the first step and the second step to increase the thickness of the glass layer. . A glass layer can be formed by performing the first step and the _second step once, respectively. Layer thickness and area can be increased. Here, the treatment is not limited to one time, and a glass layer having an arbitrary thickness and area can be formed by repeating the treatment multiple times as necessary.

Moreover, in the manufacturing method of the glass bulk body of the present invention, it is preferable that the powder is supplied to the melting section in the second step. By supplying powder containing a silica (SiO ₂ ) component to the melting portion in the second step, a dense glass layer can be formed more stably and efficiently. The powder supply method is not particularly limited, and may be supplied by conventionally known various methods. For example, a powder supply method used in laser cladding (nozzle for supplying powder to the vicinity of the fusion zone, nozzle for supplying powder coaxially with respect to laser irradiation, etc.) can be used.

Further, in the method for manufacturing a glass bulk body of the present invention, in the first step, it is preferable that the power density of the laser on the surface is 3 to 15 W/mm ² . By setting the laser power density to 3 W/mm ² or more, the silica (SiO ₂ ) component and the like contained in the substrate can be sufficiently melted to form the seed region of the glass layer. In addition, by setting it to 15 W/mm ² or less, inhibition of densification of the glass layer due to steam explosion or the like can be suppressed, and deformation of the base material can be suppressed.

Further, in the method for manufacturing a glass bulk body of the present invention, it is preferable that in the second step, the power density of the laser on the surface is 20 to 40 W/mm ² . By setting the power density of the laser to 20 W/mm ² or more, the melted state can be sufficiently maintained even if the laser irradiation position is moved, and the melted portion can be enlarged continuously. In addition, by setting it to 40 W/mm ² or less, it is possible to suppress evaporation of silica (SiO ₂ ) components, steam explosion, deformation of the base material, and the like.

Further, in the method for producing a glass bulk body of the present invention, it is preferable that the scanning speed is set to 0.01 to 2.0 m/min in the second step. By setting the scanning speed of the laser at 0.01 m/min or higher, it is possible to suppress evaporation of silica (SiO ₂ ) components and the like, steam explosion, deformation of the base material, and the like. Further, by setting the speed to 2.0 m/min or less, the molten state can be sufficiently maintained even if the laser irradiation position is moved, and the molten portion can be continuously enlarged.

Moreover, in the method for producing a glass bulk body of the present invention, it is preferable that the aggregate of sand and/or the rock exist at the outer edge of an excavation area during excavation of the ground or seabed. When excavating the ground or the seabed, it is a problem that the outer edge of the excavation area collapses during the excavation. In general, casings are used for excavation, but if strata are standing (oil field strata, etc.), they tend to collapse, and there are cases where casings cannot be used. Here, by vitrifying the region that is likely to collapse, the inner diameter becomes constant and the casing can be easily installed. Also, when using a casing, there is a problem that the inner diameter becomes smaller as the excavation depth increases. disappears.

Moreover, in the method for producing a glass bulk body of the present invention, it is preferable to take high-level radioactive waste into the melting zone. Currently, high-level radioactive waste is sealed in a stainless steel container together with molten glass to form a vitrified waste, and the container is buried in an underground facility. In addition to being necessary, a large-scale burial site is required. On the other hand, by taking high-level radioactive waste into the melting section, it can be very easily vitrified, and a large container made of stainless steel becomes unnecessary. In addition, the vitrified material can be formed deep underground, eliminating the need for a large-scale burial site.

As described above, the “in-situ production and burial” of vitrified waste containing high-level radioactive waste eliminates the need for large-scale production equipment and enables the minimum burial site. Secondary high-level radioactive waste can be reduced very effectively.

Furthermore, in the method for producing a glass bulk body of the present invention, it is preferable that the powder is placed in grooves of a concrete member, and the grooves are filled with the glass layer. By filling the grooves of the concrete member with the glass layer, the corrosion resistance and appearance of the concrete member can be improved. In addition, when a groove exists between two or more concrete members, filling the groove with a glass layer makes it possible to join these concrete members via the glass layer. A simple joining can also be achieved by aligning concrete members and forming a glass layer along the alignment line.

In addition, the present invention
a base material made of aggregates of sand grains, rocks or concrete;
a glass layer;
the substrate portion and the glass layer are continuously integrated via a boundary region having bubbles;
Also provided is a glass bulk body characterized by:

Since the glass bulk body of the present invention is formed with a glass layer made of silica (SiO ₂ ) component contained in the base material made of an aggregate of sand grains, rocks or concrete, the base material and the dense glass layer are formed. are continuously integrated. In addition, air bubbles exist in the boundary region between the base material and the glass layer, and the structure is such that the difference in physical properties between the base material and the glass layer is effectively alleviated by the air bubbles.

Moreover, in the glass bulk body of the present invention, it is preferable that the glass layer has transparency. The glass layer formed in the glass bulk body of the present invention is dense, and the glass layer has transparency. ) can be used as The glass bulk body of the present invention can be suitably obtained by the method for producing a glass bulk body of the present invention.

According to the method for producing a glass bulk body of the present invention, an aggregate of sand grains, rocks, or concrete is irradiated with a laser, and the silica (SiO ₂ ) component contained in these aggregates of sand grains, rocks, or concrete is used as a raw material. , it is possible to provide a simple method for manufacturing a glass bulk body in which a dense glass layer is continuously formed in an arbitrary region (especially in a wide region).

Further, according to the glass bulk body of the present invention, the glass bulk body is obtained by vitrifying the surface of a base material made of aggregates of sand grains, rocks or concrete and continuously forming a dense glass layer in an arbitrary region. can provide.

It is a schematic sectional drawing of the glass bulk body of this invention. 1 is a cross-sectional view of a sample obtained in Example 1. FIG. 4 is a photograph showing a state in which light is transmitted through the glass layer formed in Example 1. FIG. 4 is an appearance photograph of a sample obtained in Example 2. FIG. 4 is an appearance photograph of a sample obtained in Example 3. FIG. 10 is an appearance photograph of a concrete piece in which grooves are formed and used in Example 4. FIG. It is an enlarged photograph of a groove formed in a piece of concrete. It is an appearance photograph of a groove filled with powder. It is an appearance photograph which shows the state which vitrified the powder. 4 is an appearance photograph of the treated area finally obtained in Example 4. FIG. 4 is an appearance photograph of a concrete joint obtained in Example 5. FIG.

Hereinafter, representative embodiments of the method for producing a glass bulk body and the glass bulk body of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description may be omitted. Also, since the drawings are for the purpose of conceptually explaining the present invention, the dimensions and ratios of the depicted components may differ from the actual ones.

(1) Method for producing a glass bulk body The method for producing a glass bulk body according to the present invention is a method for producing a glass bulk body by vitrifying the surface of an aggregate of sand grains, rocks or concrete, wherein the laser is irradiated at a fixed point. and a second step of scanning the laser. Each step and the like will be described in detail below.

1. First step (fixed-point laser irradiation)
The first step is to irradiate the surface of aggregates of sand grains, rocks, or concrete with a laser at a fixed point to form a seed (melted portion) that will later become a glass layer.

Aggregates of sand grains, rocks, or concrete that serve as base materials for forming the glass layer contain a silica (SiO ₂ ) component, and the silica (SiO ₂ ) component forms the glass layer. The term "aggregate of sand grains" means a broad aggregate of sand grains, and includes, for example, aggregates of sand grains that have been hardened by applying pressure, and sand grains that exist on the ground or on the seabed.

Also, the aggregate of sand grains, rock or concrete is not particularly limited as long as it contains a silica (SiO ₂ ) component, and various conventionally known aggregates of sand grains, rocks or concrete can be used. For example, silica sand, granite, and the like can be used as sand grains, and granite, sandstone, mudstone, tuff, and the like can be used as rocks. Further, for example, a chimney, which is a structure formed by deposition and precipitation of metals contained in hot water spouting from the seabed, can also be targeted.

In addition, the type of laser used for irradiation is not particularly limited as long as the silica (SiO ₂ ) component contained in aggregates of sand grains, rocks, or concrete can be sufficiently melted, and various conventionally known lasers can be used. can be done. Here, as a laser that can be suitably used, a semiconductor-excited solid-state laser can be cited, and for example, a semiconductor laser can be used.

In the first step, the laser power density on the substrate surface is preferably 3 to 15 W/mm ² . By setting the laser power density to 3 W/mm ² or more, the silica (SiO ₂ ) component and the like contained in the substrate can be sufficiently melted to form the seed region of the glass layer. In addition, by setting it to 15 W/mm ² or less, inhibition of densification of the glass layer due to steam explosion or the like can be suppressed, and deformation of the base material can be suppressed. The power density of the laser is more preferably 5 to 10 W/mm ² .

Moreover, as a preliminary treatment step of the first step, it is preferable to dispose a powder containing a silica (SiO ₂ ) component on the substrate surface. By supplying the silica (SiO ₂ ) component from the powder in addition to the silica (SiO ₂ ) component contained in the base material, the glass layer can be formed more stably and efficiently. The powder is not particularly limited as long as it contains a silica (SiO ₂ ) component. For example, glass powder, silica particles, silica sand and granite can be used. good too.

When the powder is placed on the surface of the substrate as the preliminary treatment step of the first step, the method of placement is not particularly limited. It is preferable to equalize with .

2. Second step (laser scanning)
The second step is a step for continuously scanning the laser from the fixed-point irradiation of the laser in the first step to enlarge the melted portion (seed region of the glass layer).

In the second step, it is preferable to set the power density of the laser on the substrate surface to 20 to 40 W/mm ² . By setting the power density of the laser to 20 W/mm ² or more, the melted state can be sufficiently maintained even if the laser irradiation position is moved, and the melted portion can be enlarged continuously. In addition, by setting it to 40 W/mm ² or less, it is possible to suppress evaporation of silica (SiO ₂ ) components, steam explosion, deformation of the base material, and the like. A more preferable laser power density is 25 to 35 W/mm ² .

Also, the scanning speed of the laser is preferably 0.01 to 2.0 m/min. By setting the scanning speed of the laser at 0.01 m/min or higher, it is possible to suppress evaporation of silica (SiO ₂ ) components and the like, steam explosion, deformation of the base material, and the like. Further, by setting the speed to 2.0 m/min or less, the molten state can be sufficiently maintained even if the laser irradiation position is moved, and the molten portion can be continuously enlarged. A more preferable laser scanning speed is 0.1 to 1.0 m/min.

In the second step, it is preferable to supply the powder containing the silica (SiO ₂ ) component described above to the melting section. By supplying powder containing a silica (SiO ₂ ) component to the melting portion in the second step, a dense glass layer can be formed more stably and efficiently. The powder supply method is not particularly limited, and may be supplied by conventionally known various methods. For example, a powder supply method used in laser cladding (nozzle for supplying powder to the vicinity of the fusion zone, nozzle for supplying powder coaxially with respect to laser irradiation, etc.) can be used.

By subjecting the glass layer obtained in the second step to the pretreatment step, the first step and the second step, the thickness of the glass layer can be increased. A glass layer can be formed by performing the first step and the _second step once, respectively. Layer thickness and area can be increased. Here, the treatment is not limited to one time, and a glass layer having an arbitrary thickness and area can be formed by repeating the treatment multiple times as necessary.

In both the first step and the second step, the atmosphere of the laser irradiation region is not particularly limited, and can be performed, for example, in air or in an inert gas atmosphere.

3. Application examples of the method for producing a glass bulk body The method for producing a glass bulk body of the present invention can form a dense glass layer on an arbitrary region of the surface of aggregates of sand grains, rocks, or concrete. There are effective applications of

3-1. Collapse prevention of excavation area When excavating the ground or the seabed, it is a problem that the outer edge of the excavation area collapses during the excavation. In contrast, by vitrifying the outer edge of the excavation area (the inner diameter of the excavation area), the collapse can be extremely effectively suppressed.

For example, strata in oil fields or the like have strata, and collapse caused by fragile strata poses a serious problem. If the collapse occurs, casing cannot be carried out, but the collapse can be suppressed by forming a glass layer on the inner wall of the excavation area. In addition, it is also possible to install a casing by stabilizing the diameter and shape of the inner wall.

Also, when using a casing, there is a problem that the inner diameter becomes smaller as the excavation depth increases. disappears.

3-2. Treatment of high-level radioactive waste Currently, high-level radioactive waste is sealed in a stainless steel container together with molten glass to form a vitrified waste, and the container is buried in an underground facility. In addition to the need for large-scale manufacturing equipment, a large-scale burial site is also required. In contrast, high-level radioactive waste can be easily vitrified by taking it into the melting zone, and a large container made of stainless steel is no longer required. In addition, the vitrified material can be formed deep underground, eliminating the need for a large-scale burial site.

In-situ production and burial of vitrified waste containing high-level radioactive waste eliminates the need for large-scale production facilities and minimizes the burial site. High-level radioactive waste can be reduced very effectively.

Here, the timing of incorporating the high-level radioactive waste into the glass layer is not particularly limited. By placing the high-level radioactive waste and then performing the first step and the second step, the high-level radioactive waste can be incorporated into the glass layer. Alternatively, the high-level radioactive substance may be supplied at the same time as the powder is supplied to the melting section in the second step.

3-3. Repair, Reinforcement, and Joining of Concrete Member The concrete member can be repaired and/or reinforced by arranging the powder containing the silica (SiO ₂ ) component in the groove of the concrete member and filling the groove with a glass layer. Here, the groove may be intentionally formed, or may be a naturally occurring crack or the like. Formation of the glass layer not only improves mechanical properties and corrosion resistance, but also improves aesthetics.

Moreover, when a groove exists between two or more concrete members, by forming a glass layer in the groove, these concrete members can be joined via the glass layer. Furthermore, simple joining can be achieved by butting concrete members and forming a glass layer along the butt line.

(2) Glass Bulk Body FIG. 1 shows a schematic cross-sectional view of the glass bulk body of the present invention. The glass bulk body 2 has a base material part 4 made of an aggregate of sand grains, rocks or concrete, and a glass layer 6. continuously integrated.

The base material portion 4 is made of aggregates of sand grains, rocks or concrete, and these contain silica (SiO ₂ ) components. Aggregates of sand grains, rocks or concrete are not particularly limited as long as they contain a silica (SiO ₂ ) component, and various conventionally known aggregates of sand grains, rocks or concrete are used. For example, sand grains are silica sand, granite, etc., and rocks are granite, sandstone, mudstone, tuff, and the like. Concrete contains silica sand and clay, and these components contain silica (SiO ₂ ).

Due to the air bubbles 8 formed in the boundary region between the dense glass layer 6 and the substrate portion 4, the density difference and the physical property difference between the glass layer 6 and the substrate portion 4 are alleviated, and the glass layer 6 and the substrate portion 4 are separated. 4 are continuously integrated. Here, the size of the air bubbles 8 is preferably 50-2000 μm, more preferably 100-1500 μm. When the size of the bubbles 8 is 50 μm or more, the difference between the glass layer 6 and the substrate portion 4 can be reduced, and when the size is 2000 μm or less, embrittlement of the boundary region can be suppressed.

The glass layer 6 preferably has transparency. Since the glass layer 6 has transparency, it can be utilized, for example, as a building member (outer wall, etc.) having excellent aesthetic appearance using the transmission of light. The glass bulk body of the present invention can be suitably obtained by the method for producing a glass bulk body of the present invention.

Although representative embodiments of the present invention have been described above, the present invention is not limited to these, and various design changes are possible, and all such design changes are included in the technical scope of the present invention. be

<<Example 1>>
A semiconductor laser manufactured by Laserline was used to irradiate the surface of the sandstone with a laser. Specifically, the laser output was 800 W, the laser beam diameter on the surface of the sandstone was 2×39 mm, and fixed-point irradiation was performed for 60 seconds (first step). The laser power density in the first step is 10 W/mm ² .

Since formation of a sufficient melted region was confirmed by fixed-point irradiation in the first step, the laser output was increased to 2800 W, and the laser irradiation position was moved at a moving speed of 48 mm/min (second step). The laser power density in the second step is 35 W/mm ² . By setting an appropriate laser power density and moving speed, the laser scanning continuously expanded the melted portion without interrupting the melted portion. Figure 2 shows a cross-sectional photograph of sandstone after treatment.

From FIG. 2, it can be seen that a dense glass layer is extensively formed on the surface region of the sandstone. Further, the glass layer is continuously formed from sandstone as a base material, and air bubbles are formed at the boundary between the glass layer and the base material. The cracks in the sandstone were mainly generated when the cross-sectional samples were prepared.

FIG. 3 shows a state in which the obtained glass layer was separated and irradiated with light from the back side. The light irradiated from the back side is transmitted through the glass layer, and it can be confirmed that the formed glass layer has transparency.

<<Example 2>>
A semiconductor laser manufactured by Laserline was used to irradiate the surface of the tuff with a laser. Specifically, the laser output was 800 W, the laser beam diameter on the surface of the tuff was 2×39 mm, and fixed-point irradiation was performed for 60 seconds (first step). The laser power density in the first step is 10 W/mm ² .

Since formation of a sufficient melted region was confirmed by fixed-point irradiation in the first step, the laser output was increased to 2800 W, and the laser irradiation position was moved at a moving speed of 48 mm/min (second step). The laser power density in the second step is 35 W/mm ² . By setting an appropriate laser power density and moving speed, the laser scanning continuously expanded the melted portion without interrupting the melted portion.

In the second step, a powder containing tuff constituents was fed into the melting section. By supplying powder containing tuff components to the melting zone in the second step, a dense glass layer can be formed more stably and efficiently. Figure 4 shows a photograph of the appearance of the tuff after treatment.

From FIG. 4, it can be seen that a transparent dense glass bulk body is extensively formed in the surface region of the tuff. Further, the glass bulk body is formed continuously from the tuff which is the base material, and no defects such as cracks are observed at the boundary between the glass bulk body and the base material.

<<Example 3>>
A semiconductor laser manufactured by Laserline was used to irradiate the concrete surface with laser light. Specifically, the laser output was 2800 W, the diameter of the laser beam on the concrete surface was 2×39 mm, and fixed-point irradiation was performed for 1 second (first step). The laser power density in the first step is 35 W/mm ² .

Since formation of a sufficient melted region was confirmed by fixed-point irradiation in the first step, the laser irradiation position was moved at a moving speed of 48 mm/min (second step). Incidentally, in this embodiment, the laser output in the second step is not increased from that in the first step.

A photograph of the appearance of the obtained sample is shown in FIG. It can be seen that in Example 3, a black glass layer is formed over a wide area.

<<Example 4>>
An attempt was made to fill a groove (depth 20 mm, length 100 mm) formed on the concrete surface with a glass layer using a semiconductor laser manufactured by Laserline. A photograph of the appearance of a concrete piece having grooves is shown in FIG. An enlarged photograph of the groove is shown in FIG. Here, for the first layer, a glass layer is formed by directly irradiating the bottom of the groove with a laser, and for the second to fifth layers, the groove is filled with sand-like powder obtained by pulverizing silica sand, and the laser is applied to the region. was irradiated to sequentially form glass layers.

For the formation of the first layer, the laser output was 540 W and the laser beam diameter at the bottom surface of the groove was 2×27 mm, and fixed-point irradiation was performed for 1 second (first step). The laser power density in the first step is 10 W/mm ² . After that, the laser output was set to 1900 W, and the laser was scanned at a speed of 48 mm/min. The laser power density in the second step is 35 W/mm ² .

For the formation of the second to fifth layers, sand-like powder obtained by pulverizing silica sand was supplied to the fusion zone, the laser output was set to 1900 W, and the laser was scanned at a speed of 48 mm/min. The laser power density in this process is 35 W/mm ² .

8 and 9 show photographs of the appearance of the grooves filled with the powder and photographs of the appearance after vitrification of the region, respectively. It can be seen that the filled powder (silica sand powder) becomes dense glass by laser irradiation.

FIG. 10 shows an enlarged photograph of the grooves of the finally obtained sample. The grooves are completely filled with dense glass layers, and it can be seen that even deep grooves can be filled up to the surface by multiple glass layers.

<<Example 5>>
Using a semiconductor laser manufactured by Laserline, we attempted to join concrete pieces together. The end faces of the concrete pieces were brought into contact with each other, and the peripheral regions of the end faces were vitrified for joining. Here, powder having a height of about 3 mm to 5 mm was supplied to the laser irradiation surface, and sand-like powder obtained by pulverizing sandstone was used as the powder.

Specifically, the laser output was 1900 W, the diameter of the laser beam on the concrete surface was 2×27 mm, and fixed-point irradiation was performed for 1 second (first step). The laser power density in the first step is 35 W/mm ² . After that, the laser irradiation position was moved at a speed of 48 mm/min along the outer peripheral region of the end face (second step). Incidentally, in this embodiment, the laser output in the second step is not increased from that in the first step.

FIG. 11 shows a photograph of the appearance of the sample after the outer peripheral region of the end face was irradiated with the laser twice. It can be confirmed that the outer peripheral area of the butt end face is vitrified and two pieces of concrete are joined.

2... glass bulk body,
4 ... base material part,
6... glass layer,
8... Bubbles.

Claims (7)

A method for producing a glass bulk body by vitrifying the surface of an aggregate of sand grains, rocks or concrete, comprising:
the aggregate of sand grains, the rock and the concrete contain a silica (SiO ₂ ) component,
a first step of irradiating the surface with a laser at a fixed point to form a melted portion;
a second step of moving the irradiation position of the laser at a scanning speed at which the melted portion continuously expands to form a glass layer;
The first step and the second step are continuously performed,
In the first step, the power density of the laser on the surface is 3 to 15 W / mm ² ,
In the second step, the power density of the laser on the surface is 20 to 40 W / mm ² ,
setting the scanning speed to 0.01 to 2.0 m/min in the second step;
A method for producing a glass bulk body, characterized by: Placing a powder containing a silica (SiO ₂ ) component on the surface as a preliminary treatment step of the first step;
The method for producing a glass bulk body according to claim 1, characterized by: subjecting the glass layer to the pretreatment step, the first step and the second step to increase the thickness of the glass layer;
The method for producing a glass bulk body according to claim 2, characterized by: supplying the powder to the melting section in the second step;
The method for producing a glass bulk body according to claim 2 or 3, characterized by: said aggregates of sand and/or said rocks are present at the outer edge of an excavation area when excavating the ground or seabed;
The method for producing a glass bulk body according to any one of claims 1 to 4, characterized by: incorporating high-level radioactive waste into the fusion zone;
The method for producing a glass bulk body according to any one of claims 1 to 5, characterized by: placing the powder in the groove of the concrete member;
filling the groove with the glass layer;
The method for producing a glass bulk body according to any one of claims 2 to 6, characterized by:

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