JPH0788770A - Shot blast material - Google Patents

Abstract

PURPOSE:To provide a shot blast material effectively acting for giving excellent coating adhesion on one hand and slight corrosion resistance to a processed material surface without generating dust according to powdering the shot blast material in the case of blast processing. CONSTITUTION:A composition of a principal component is formed of granular matter of high carbon ferrochrome refined slug constituted by containing 20 to 40wt.% MgO, 20 to 40wt.% Al2O3, 25 to 45wt.% SiO2 and the rest of the other small amount of oxide, to provide 0.2 to 2.5mm grain size of the granular matter, and further in this granular matter, most of sizes for showing a maximum value of grain size distribution curve are set to 0.9 to 1.4mm size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abrasive cleaning material, and in particular, in the blasting process prior to surface coating of ships, bridges, oil tanks, gates, etc., no dust is generated. Further, the present invention provides a polishing / cleaning material which has an excellent polishing / cleaning effect (workability) and which can be effectively used for improving the adhesion between the paint and the coated surface.

[0002]

2. Description of the Related Art Generally, when coating the surface of a steel material such as ordinary steel, special steel or alloy steel (hereinafter referred to as "steel to be treated"), the surface of the steel material is polished and cleaned before the coating treatment. The so-called "blast treatment" is performed. One of the purposes of this blasting treatment is to remove the oxide layer, surface contaminants, or old paint surface of the surface of the steel to be treated by peeling off to form a clean surface suitable for painting, and thus the paint and the surface of the material to be treated. It is to improve the adhesion with. In this treatment, it is important to remove as much as possible the oxide layer, contaminants, old paint layer, etc. on the surface of the material to be treated.
Judgment is made using an index called "polishing effect". Also,
The other purpose of this treatment is to increase the adhesion of the coating,
The purpose is to make unevenness of appropriate roughness on the surface to be coated.

Generally, it is said that the "coating adhesion" and the "surface roughness" of the surface to be coated have a close relationship, and the surface shape of the treated steel material for improving the coating adhesion is fine and It is preferable that it has deep irregularities. This is because by making the surface of the steel material to be treated such a surface roughness, the so-called anchor effect is enhanced and the adhesion of the coating is improved. Therefore, conventionally, the blasting treatment is performed to make the surface of the steel material to have a predetermined roughness, and in fact, the coating adhesion that is satisfactory to that extent is actually obtained. Note that sand, grids, garnets, glass beads, steel balls, converter slag, and the like are well known as abrasives used for such blast treatment.

[0004]

By the way, when the blast treatment of the material to be treated is carried out using such a cleaning material,
Garnets, glass beads, and abrasive materials such as converter slag, the abrasive material is cracked and powdered by the impact when sprayed on the surface of the material to be treated, dust is scattered all over the workplace, and the blasting operation itself There was a problem of becoming an environment that cannot be done. In addition, with the above-mentioned abrasives, in order to obtain a satisfactory anchor effect or to completely remove old paint, the surface of the material to be treated is slowly blasted over time or this treatment is performed. It had to be repeated. Therefore, there is a problem in that the work time for the blast treatment is long and the so-called "polishing effect" is poor. In addition, there is a problem that rusting occurs early after the blast treatment because the film is exposed to the atmosphere without a protective film.

In this respect, the above-mentioned abrasive materials such as grids and steel balls have a small dust diffusion and are excellent in abrasive effect, but they must be treated outdoors, and blasting of ships, bridges, gates, etc. In the case of treatment, if the above-mentioned known cleaning agents are used, the surface of the material to be treated will rust in a short time due to the influence of humidity because it will be exposed to the atmosphere without a protective film, There is a problem in that the adhesiveness with and deteriorates, and the paint applied to the surface of the material to be treated is easily peeled off. Moreover, the cleaning and cleaning materials themselves are apt to rust due to moisture, and there is even a problem that the cleaning and cleaning materials stick to each other and cannot be used. Therefore, known abrasives such as grids and steel balls
Currently, the usable environment is limited.

An object of the present invention is to effectively prevent dust from being generated due to pulverization of a cleaning material during blasting, and to impart excellent coating adhesion and some corrosion resistance to the surface of the material to be treated. To provide abrasives.

[0007]

As a result of continuing intensive research to solve the problems of the above-mentioned prior art, the inventors have conceived the present invention having the following gist structure. . That is, in the present invention, the main component composition is MgO: 20-
_{40wt%, Al 2 O 3:} 20~40wt%, SiO 2: comprises 25～45Wt%, consists granules high carbon ferrochromium refining slag balance is configured to contain a small amount of other oxides, and It is a polishing and cleaning material characterized by having a particle size of 0.2 to 2.5 mm. The refined slag granules preferably have a maximum diameter showing a maximum value of a particle size distribution curve of 0.9 to 1.4 mm, and the granules are produced by rapid solidification such as air crushing. Those having a spherical shape or a substantially spherical shape are preferable.

[0008]

A feature of the blast cleaning material according to the present invention is that it uses oxide-based refining slag particles containing at least Mg, Al and Si oxides as main components. First of all, the reason for paying attention to the refining slag is, as will be described in detail later, that it has an internal structure that is difficult to crack even if it collides with the surface of the material to be treated during blasting, and does not generate dust even if it breaks. The excellent scavenging effect enables blasting in a short time. Further, since it is possible to impart a slight amount of corrosion resistance to the material to be treated, it is not necessary to consider the influence of rusting so much even if there is a time interval between coatings, and it is possible to easily control the coating process. .

In the present invention, as such a blasting material, among the oxide-based refining slag, the molten slag, which is by-produced when the high carbon ferrochrome is melted in an electric furnace to be manufactured, is granulated. Those used are shown in Table 1 as an example of the component composition.

[0010]

[Table 1]

In the present invention, among the above-mentioned refining slags, the reason for paying particular attention to the high carbon ferrochrome refining slag is that the refining slag is hard and difficult to crack because it contains oxides of Mg, Al and Si. And, the structure is mainly in the spinel structure of Mg and Al oxides. Therefore,
In the blasting treatment, even if the material is cracked by the impact when it collides with the surface of the material to be treated, the material is broken at the crystal grain boundaries, so that it does not become a fine powder but becomes a relatively large granular material and does not generate dust. Further, since it has high hardness and excellent toughness, it is effective in forming an appropriate anchor on the surface of the material to be treated by the blast treatment. Furthermore, when this abrasive material is strongly sprayed onto the steel surface to be treated, it mechanically bonds with Fe on the steel surface, or sometimes reacts with each other, and the oxide on the surface of the treated steel appears as if it were an oxide such as an alloy layer. Form a permeation layer. Moreover, the oxide permeation layer does not easily peel off and is present as a so-called modified layer on the surface of the steel material.

The abrasive cleaning material of the present invention is, among the above-mentioned high carbon ferrochrome refining slags, in particular, a rapid solidification produced by a method of spraying a molten slag into the air, not a crushed and sized granule. Object; that is, it is preferable to use a granular material having a spherical shape or a substantially spherical shape. The reason is that in the case of such granular slag, the collision energy when colliding with the steel to be treated is extremely high, and mainly Mg,
This is because it is possible to easily form a surface modification layer composed of an oxide permeation layer which is formed by mixing or reacting the oxides of Al and Si with Fe in the vicinity of the surface of the steel to be treated and reacting with them.

By the way, in the present invention, the above-mentioned Mg,
By using the refining slag of the oxide containing Al and Si, the effects of the present invention can be realized, but, of course, such effects of the present invention are limited to only high carbon ferrochrome refining slag. Needless to say, it can be realized by using a composition having the same components alone and using the composition produced in an electric furnace or the like to form a granular material.

Here, the composition of the main components of the high carbon ferrochrome refining slag is as follows: Al ₂ O ₃ : 20-40 wt%, MgO:
20 to 40 wt%, SiO ₂ : 25 to 45 wt%, and the balance consisting of a small amount of other oxides is used. The reason why the component composition of this slag is limited to the above range is as follows. First,
The composition of Al ₂ O ₃ , MgO, and SiO ₂ is limited as described above, with the slag of this composition, there is less generation of dust, and it is necessary to improve the adhesion between the paint and the coating surface during coating. This is because the cleaning effect is high. Although it has not been fully clarified, the inventors believe that a large amount of Al ₂ O ₃ increases both hardness and toughness, which is preferable, but too large an amount makes it brittle. And easily cracked. However, if the amount is too small, the hardness becomes low and the toughness becomes small, so that it is easily cracked and pulverized, so that it is limited to the above range. In order to increase the Al content in the slag, it is an effective means to previously add an aluminum oxide raw material into the electric furnace and adjust the aluminum content in the refining slag.

MgO, SiO₂Influences the improvement of hardness and toughness.
Factor, especially MgO₂O ₃Forming a spinel with
However, when the hardness increases and it collides with the surface of the processed material, powder
It is a component to prevent conversion, especially Al₂O₃Balance with
Above, it is limited to the above range.

In addition to the above, CaO may be contained, but if this Ca is large, the slag becomes alkaline, and it becomes soft and brittle and easily pulverizes, so 10 wt% or less, preferably 4.0 It is preferably not more than wt%.

When using the above-mentioned refined slag particles, it is necessary to adjust the particle size to a suitable size. That is, such a suitable particle size is 0.
Use a 2-2.5 mm one. If the lower limit particle size is less than 0.2 mm, it will not crack, but will behave as if it were dust and fly up to the atmosphere because the particle size itself becomes smaller. On the other hand, if the upper limit particle size exceeds 2.5 mm,
On the contrary, it becomes easier to crack and less likely to be pulverized. From this, it is necessary to use the abrasive material of the present invention having a particle size in the range of 0.2 to 2.5 mm.

The polishing and cleaning material preferably has a maximum number of particles (particle size showing the maximum value of the particle size distribution curve) of 0.9 to 1.4 mm. However, the time required for polishing and cleaning will be too long, the cleaning and cleaning effect will decrease, and the amount of polishing and cleaning material used will increase.
This is because if it exceeds 4 mm, it is likely to be cracked and powdered, and the polishing effect is rather reduced. Further, the particle size distribution for obtaining such a maximum number of diameters is preferably in the following range. 0.2 to 0.4 mm: 3 to 15% 0.4 to 0.6 mm: 5 to 20% 0.6 to 1.2 mm: 30 to 45% 1.2 to 2.5 mm: 30 to 50% is preferable. In the present invention, 0.2-
0.6 mm: 50 to 70%, 0.6 to 2.5 mm: 30 to 50% As the particle size distribution is adjusted to 0.4 to 0.8 mm, the polishing effect is reduced, but the ISO standard The adjustment rank can be increased from near white to white.

[0019]

EXAMPLES Examples of the present invention will be described below. (1) The molten slag produced as a by-product in the refining process of high carbon ferrochrome is stored in a ladle, and by spraying this in the atmosphere and quenching it, a granular body having a spherical shape and a substantially spherical shape, that is,
A granular body of refined slag was obtained. Then from this granulate
Those having a diameter of 0.2 to 2.5 mm were selected to be a polishing / cleaning material [A], and those having a diameter of 0.4 to 2.5 mm were selected to have a predetermined particle size distribution to obtain a polishing / cleaning material [B]. In addition, abrasives having a diameter of 0.2 to 1.2 mm were similarly selected so as to have a specific particle size distribution to obtain a polishing and cleaning material [C]. The particle size distribution is shown in Table 2.

[0020]

[Table 2]

(2) Next, a general structural mild steel SS 400 steel plate (100 × 100 × 1.6 mm) was used as the steel to be treated, which was installed in a normal direct pressure type blast treatment equipment, and then ISO Sa
Blasting treatment was carried out using the above-mentioned abrasive cleaning materials [A], [B] and [C] so that the finish was 2.5. In addition, as a comparative example, in the above-mentioned SS 400 steel sheet, by the method usually performed,
Sand blasting and grid blasting were performed.

During this treatment, paints and adhesives were intentionally attached as contaminants on all the above steel plates.
By this blasting treatment, the surface contaminants were completely removed in both the inventive example and the comparative example. The results at that time are shown in Table 3. From Table 3, the abrasive materials [A] and [B] of the present invention
It was found that each of them had an extremely high polishing speed, a small amount of polishing material used per unit area, and excellent workability (polishing effect). On the other hand, it was found that the polishing and cleaning material [C] had a low polishing and cleaning speed but a small amount used per unit area, and the foundation adjustment rank was improved.

[0023]

[Table 3]

Then, the abrasive cleaning agent [A] of the present invention and the conventional abrasive cleaning agent (garnet) were repeatedly subjected to a suction blast treatment, and after the treatment, they were sieved with a 0.42 mm sieve (reusable abrasive cleaning). The residual rate (of the material) was measured. The results are shown in Table 4. From the results shown in Table 4, more than half of the garnet was pulverized after 5 cycles, but the abrasive material of the present invention remained spherical for 65% or more even after 30 cycles. Further, during the blasting work, the garnet generated a lot of dust, and it was necessary to wear a dust mask, but the abrasive material of the present invention generated very little dust.

[0025]

[Table 4]

Further, the surface of the treated steel material obtained by each of the above treatments was analyzed by the X-ray microscopic analysis method (EPMA) and Auger electron spectroscopy (AES). The result is shown in FIG. From Fig. 1, it was observed that the treated material had a part in which the slag substance was implanted, but the entire surface of the sample was mixed with Mg, Al, Si, and Ca, which are slag components, and Fe and oxygen, which were the base materials. A reacted layer was confirmed. Also,
It was confirmed that the thickness of this surface-modified layer was at least 0.5 μm or more, although it varied depending on the site.

On the other hand, no remarkable existence of elements other than Fe and O was confirmed on the surface of the treated steel material subjected to the general sandblasting treatment and the sandblasting treatment and the grid blasting treatment.

[0028]

As described above, the polishing / cleaning material of the present invention has an excellent polishing / cleaning effect, but has extremely little dust generation and excellent workability. Moreover, since it acts effectively on the surface of the material to be treated to form a surface-modified layer in which the composition of the slag component and the base material (Fe) is mixed and reacted, it imparts extremely high coating adhesion to the surface of the steel material. be able to.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a result of AES depth analysis showing a surface state of a treated steel material showing an experimental result of an example.

Claims (3)

[Claims] 1. The composition of the main components is MgO: 20-40 wt%,
Al ₂ O ₃ : 20 to 40 wt%, SiO ₂ : 25 to 45 wt%, the balance consisting of granular particles of high carbon ferrochrome refining slag composed of a small amount of other oxides, and its particle size But
Abrasive cleaning material characterized by having a size of 0.2 to 2.5 mm. 2. The cleaning and cleaning material according to claim 1, wherein the fine particles of the refined slag have a maximum diameter of 0.9 to 1.4 mm that indicates the maximum value of the particle size distribution curve. 3. The abrasive material according to claim 1, wherein the granular material of refining slag is produced by rapid solidification.