JPH08327604A - Fluorescent magnetic powder for magnetic particle testing and production thereof - Google Patents

Abstract

PURPOSE: To produce highly sensitive inexpensive fluorescent magnetic powder for magnetic particle testing. CONSTITUTION: 60-90wt.% of magnetically conductive iron oxide particles having mean particle size of 2-5μm is admixed with 3-20wt.% of white inorganic particles having mean particle size of 0.02-1μm. The mixed particles collide each other to cause mechanochemical reaction and each white inorganic particle adheres to the surface of each magnetically conductive iron oxide particle thus forming a first coating layer. The magnetically conductive iron oxide particles forming the first coating layer is admixed with 2-10wt.% of fluorescent coloring material particles having mean particle size of 0.1-0.5μm. The mixed particles collide each other to cause mechanochemical reaction and each fluorescent coloring material particle adheres to the surface of first coating layer to form a second coating layer thus producing fluorescent magnetic powder for magnetic particle testing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent magnetic powder for magnetic particle flaw detection test and a method for producing the same.

The fluorescent magnetic powder according to the present invention is mainly used in a magnetic particle flaw detection test method which is widely used in steel manufacturers, automobile manufacturers and the like.

[0003]

2. Description of the Related Art As is well known, steel materials such as square billets and round billets and steel parts such as shafts and knuckle arms can be magnetized by energization. Therefore, JIS G 0565 is required for nondestructive inspection. The magnetic particle flaw test method standardized in 1992 is applied.

As seen in the JIS standard, one of the magnetic particle flaw detection test methods is a test method using fluorescent magnetic powder.
The fluorescent magnetic powder is a fluorescent light that is excited by ultraviolet irradiation on the particle surface of magnetically conductive particle powder (for example, Fe particle powder, Fe ₃ O ₄ particle powder, γ-Fe ₂ O ₃ particle powder) and emits yellow to yellowish green light. Coloring material (eg fluorescent dye, fluorescent pigment)
Is colored with.

[0005] The fluorescent magnetic powder is obtained by fixing a fluorescent coloring material to a magnetic conductive particle powder with a synthetic resin as a binding material (hereinafter referred to as "binder use type"), and binding the fluorescent coloring material to the magnetic conductive particle powder. There are two types, one that is fixed without using a material (hereinafter referred to as "no binding material type").

Fluorescent magnetic powders using a binder have been used for a long time and are still in widespread use, and most of them are magnetic powder particles called "pulverization method", synthetic resin as a binder, and A fluorescent coloring material is dissolved or dispersed in a volatile solvent and kneaded to form a paste, and the paste is dried,
It is produced by a method of pulverizing the dried product into fine particles.

In the case of the pulverization method, the particle surface of the fluorescent magnetic powder is in a state in which the fluorescent coloring material and the synthetic resin are mixed, and moreover, most of the mixed fluorescent coloring materials are contained in the synthetic resin layer. Therefore, in view of the difficulty in obtaining sufficient fluorescence brightness during flaw detection (at the time of irradiation with ultraviolet rays), the applicant has fixed a synthetic resin as a binder on the surface of each particle of the magnetically conductive particle powder by a mechanochemical reaction. After that, a method for obtaining a fluorescent magnetic powder using a binder by adhering fluorescent colorant particles to the surface by a mechanochemical reaction has been proposed (JP-A-63-304153).

Next, a typical method of producing a binderless type fluorescent magnetic powder is called an "adsorption method", which is an aromatic aldehyde having a hydroxyl group at the ortho position (of a fluorescent dye). Magnetic powder particles are dispersed in a hydroalcoholic solution in which the intermediate) is dissolved, and hydrazine is added to the dispersion to precipitate a fluorescent dye having a hydroxyl group at the ortho position of the azomethine bond in the liquid and This is a method of adsorbing onto the surface of each particle of the magnetically conductive particle powder (Japanese Patent Publication No. 48-30223).

In the case of the above-mentioned adsorption method, the selection range of the fluorescent coloring material is remarkably limited, and it is necessary to use a large amount of the fluorescent dye intermediate. In view of the complications, the Applicant has
Proposed is a method of obtaining a binderless fluorescent magnetic powder by fixing fluorescent colorant particles to the surface of each particle of magnetically conductive particle powder by a mechanochemical reaction (JP-A-63-30).
No. 4152).

[0010]

Recently, as the quality control standards of the steel materials and the steel parts become stricter, the amount of fluorescent magnetic powder used for magnetic particle flaw detection test is increasing in steel manufacturers and automobile manufacturers. Users have demanded to provide inexpensive and highly sensitive fluorescent magnetic powder.

The present inventor, in view of the advantage of manufacturing cost, etc., proceeded with experiments and trial manufacture in order to provide an inexpensive and highly sensitive fluorescent magnetic powder by using the method described in Japanese Patent Laid-Open No. 63-304152. I faced the following problems.

That is, among the magnetically conductive particle powders, the Fe particle powder is expensive and has a high specific gravity. Therefore, the fluorescent magnetic powder using the powder is wet (dispersing the fluorescent magnetic powder in water to inspect the dispersion). When it is used in a method applied to an object, the accuracy of defect detection is lowered because sedimentation is likely to occur. On the other hand, the Fe ₃ O ₄ particle powder and the γ-Fe ₂ O ₃ particle powder are cheaper and have a lower specific gravity than the Fe particle powder, and in the case of the fluorescent magnetic powder using these particles, defects caused by sedimentation A decrease in detection accuracy can be avoided.

However, Fe ₃ O _{4 is} used as the magnetically conductive particle powder.
In the case of producing a binderless type fluorescent magnetic powder by the method described in JP-A-63-304152, using the particle powder or the γ-Fe ₂ O ₃ particle powder, as shown in Comparative Examples below, If the blending ratio of the fluorescent coloring material is not increased, sufficient fluorescent brightness cannot be obtained during flaw detection, and if the blending ratio of the fluorescent coloring material is increased so that sufficient fluorescent brightness is obtained,
Since the fluorescent coloring material is expensive, the product cost is increased, the magnetic sensitivity of the fluorescent magnetic powder is reduced, and the defect detection accuracy is deteriorated.

The present inventor has solved the above-mentioned problems and has utilized the method described in Japanese Patent Laid-Open No. 63-304152 mentioned above.
As a technical challenge to manufacture inexpensive and highly sensitive fluorescent magnetic powder, we proceeded with further experiments and trial production.

Then, the present inventor pursued a phenomenon in which sufficient fluorescent brightness cannot be obtained at the time of flaw detection unless the mixing ratio of the fluorescent coloring material is increased, and as a result, Fe ₃ O ₄ particles and γ-Fe ₂ O _{3 are obtained.}
If the fluorescent coloring material is directly adhered to the surface of the particles,
Since the color of each particle surface is black, when the fluorescent coloring material fixed to the surface is excited by ultraviolet irradiation and emits yellow to yellowish green, the reflectance from each particle surface is extremely high. Since it is very small, it has been found that sufficient fluorescent brightness cannot be obtained unless the mixing ratio of the fluorescent coloring material is increased.

Therefore, the inventor of the present invention seeks a technical means capable of increasing the reflectance and suppressing the deterioration of the magnetic sensitivity to such an extent that the defect detection accuracy is not adversely affected. As a result of repeating the trial production,
The present invention has been reached.

[0017]

That is, according to the present invention, 60 to 90% by weight of magnetically conductive iron oxide particles having an average particle diameter of 2 to 5 μm,
3 to 20% by weight of white inorganic particles having an average particle size of 0.02 to 1 μm and 2 to 10% by weight of fluorescent colorant particles having an average particle size of 0.1 to 0.5 μm are blended, and the magnetically conductive oxide The white inorganic particles are fixed to the surface of the iron particles as a first coating layer by a mechanochemical reaction, and the fluorescent colorant particles are fixed to the surface of the iron particles as a second coating layer by a mechanochemical reaction. It is a fluorescent magnetic powder for magnetic particle flaw detection testing.

According to the present invention, 60 to 90% by weight of magnetically conductive iron oxide particles having an average particle diameter of 2 to 5 μm and an average particle diameter of 0.0
3 to 20% by weight of white inorganic particle powder of 2-1 μm is mixed in the state of primary particles, and the mixed powder is accelerated in the gas phase to a particle velocity of 60 to 160 m / sec to cause particles to collide with each other to cause a mechanochemical reaction. By performing the above, each particle of the white inorganic particle powder is fixed to each particle surface of the magnetically conductive iron oxide particle powder to form a first coating layer, and then the first coating layer is formed. Magnetic iron oxide particles powder with fluorescent colorant particle powder 2 having an average particle size of 0.1 to 0.5 μm
10% by weight (ratio to the total amount) of primary particles is added and mixed, and the mixed powder is mixed in the gas phase with a particle velocity of 60.
The particles of the fluorescent colorant particle powder are fixed to the surface of the first coating layer by accelerating to ~ 160 m / sec to cause the particles to collide with each other to perform a mechanochemical reaction.
A method for producing a fluorescent magnetic powder for a magnetic particle flaw detection test, which comprises forming a coating layer.

The structure of the present invention will be described in more detail below. First, in the present invention, the average particle diameter of 2 to
A magnetic iron oxide particle powder having an average particle diameter within the range of 5 μm is used. Fe ₃ O ₄ particle powder and γ-Fe ₂ O ₃ particle powder are preferable as the iron oxide particle powder, and each of the particle powders is commonly used as a material of the fluorescent magnetic powder for magnetic particle flaw detection test, and is commercially available. The one having the required average particle diameter can be easily obtained.

Iron oxide particles having an average particle size of less than 2 μm are practical, because ultrafine particles (less than 0.02 μm) must be selected as white inorganic particle powder to be fixed to the surface of each particle by a mechanochemical reaction. In addition, iron oxide particles having an average particle size of more than 5 μm are difficult to obtain.

If necessary, iron oxide particles having an average particle size of less than 2 μm may be granulated and used as large particles.

The compounding ratio of the above magnetic iron oxide particles is
If it is less than 60% by weight, the magnetic sensitivity of the obtained fluorescent magnetic powder will be less than 0.4 (value by the later-described measurement method), and the defect detection accuracy will be deteriorated. If it exceeds 95% by weight, it will be relatively white. Since the blending ratio of the inorganic particle powder and the fluorescent coloring material particle powder is reduced, sufficient fluorescence brightness cannot be obtained during flaw detection, and the defect detection accuracy is deteriorated. A particularly preferable mixing ratio is 80
~ 90% by weight.

Next, in the present invention, the average particle size is 0.
A white inorganic particle powder having an average particle diameter in the range of 02 to 1 μm is used. As this inorganic particle powder,
Titanium oxide particles powder, kaolin particles powder, silica particles powder, zinc white particles powder, antimony white particles powder, magnesium carbonate particles powder and calcium carbonate particles powder, whose whiteness is 85% or more (value by the later-mentioned measurement method. The thing of () is preferable. These particle powders are commonly used for extender pigments and the like, and those having a required average particle diameter can be easily obtained from commercial products. Titanium oxide particle powder is particularly preferable in terms of whiteness and price.

White inorganic particle powders having an average particle size of less than 0.02 μm are not practical because the required whiteness cannot be obtained, and white inorganic particle powders having an average particle size of more than 1 μm are the above-mentioned magnetic iron oxide powder particles. It is difficult to fix each particle surface by a mechanochemical reaction.

When the blending ratio of the white inorganic particle powder is less than 3% by weight, the amount of the magnetically conductive iron oxide particle powder adhered to the surface of each particle is too small, and the fluorescent brightness at the time of flaw detection of the obtained fluorescent magnetic powder is If the effect is not increased, and if it exceeds 20% by weight, the compounding ratio of the magnetically conductive iron oxide particle powder is relatively reduced, so that the magnetic sensitivity of the obtained fluorescent magnetic powder is deteriorated and the magnetically conductive iron oxide particle powder is obtained. There is a large amount of falling off without sticking to.

Next, in the present invention, the average particle size is 0.
Fluorescent colorant particle powder of 1 to 0.5 μm is used. The fluorescent colorant particle powder may be selected from among fluorescent pigments that are commonly used as materials for fluorescent magnetic powder for magnetic particle flaw detection tests, and can be easily obtained from commercial products, and the average particle size of commercial products is usually 0. 0.1 to 0.5 μm. Specific examples of preferred ones include Lumogen Yellow (trade name: manufactured by BASF) and Festa fluorescent pigment (trade name: manufactured by Swada Limited: product numbers E-27, GT-27 and HM).
P-27), and these have an average particle size of 0.1 to 0.1.
It is a particle powder in the range of 0.5 μm, and it is excited by irradiation of ultraviolet rays and emits yellow to yellowish green light.

The mixing ratio of the fluorescent colorant particle powder is 2
If the amount is less than the weight%, it is difficult to obtain sufficient fluorescence brightness during flaw detection, and the defect detection accuracy is deteriorated. When the amount is 2 parts by weight or more, the defect detection accuracy is practically sufficient. Therefore, the amount is usually 2% by weight, and the amount exceeding 10% by weight is obtained because the compounding ratio of the magnetic iron oxide particles decreases. This should be avoided because the magnetic sensitivity of the fluorescent magnetic powder deteriorates.

Next, the fluorescent magnetic powder for magnetic particle flaw detection test according to the present invention is easy to produce, and the desired product is obtained by performing a mechanochemical reaction using a high-speed crusher equipped with a rotary blade according to a conventional method. can get.

That is, one having the required average particle diameter is selected from the magnetically conductive iron oxide particles and the required amount is weighed, and one having the required particle diameter is selected from the white inorganic particle powders. The required amount is weighed, both weighed powders are put into the above-mentioned pulverizer, and both powders in the state of primary particles are accelerated in the gas phase to a particle velocity of 60 to 160 m / sec, and the particles are mixed with each other. For about 2 to 5 minutes, the magnetic iron oxide particles become core particles, and the white inorganic particles as child particles adhere to the surface of the core particles to form the first coating layer.

If the particle velocity is not accelerated to 60 m / sec or more, the mechanical and thermal energy required to fix the child particles to the core particles cannot be obtained, and the particles are strongly fixed as the particle speed is increased. It is possible, but practically 160 m
/ sec is enough. Further, the collision time needs to be at least 2 minutes or more, and the longer the time, the stronger the fixation can be made, but in practice, about 5 minutes is sufficient.

In selecting the average particle diameters of the two powders, it goes without saying that the average particle diameter of the magnetically conductive iron oxide particle powder to be the core particles and the white inorganic particle powder to be the child particles. It is preferable that the difference from the average particle diameter of is as large as possible.

By the above-mentioned operation, the particles of the white inorganic particle powder are fixed to the surfaces of the particles of the magnetically conductive iron oxide particle powder to form the first coating layer, and then the first coating layer is formed. A required amount of the fluorescent coloring material particle powder was added to the magnetic iron oxide particle powder, and both powders were in the form of primary particles in the gas phase by using the above pulverizer, and the powder particles had a particle velocity of 60 to 160.
By accelerating to m / sec and causing the particles to collide with each other for about 1 to 3 minutes, the magnetically conductive iron oxide particle powder becomes a core particle, and the fluorescent coloring material particle is fixed as a child particle on the surface of the second particle. A coating layer is formed.

If the particle velocity is not accelerated to 60 m / sec or more, the mechanical and thermal energy required for fixing the child particles to the core particles cannot be obtained, as in the case of forming the first coating layer. The higher the particle velocity, the stronger the fixation. However, up to 160 m / sec is sufficient for practical use. Further, the collision time needs to be at least 1 minute or more, and the longer the time, the stronger the fixation will be, but practically about 3 minutes is sufficient.

The average particle size of the fluorescent colorant particle powder to be used may be any one as long as it is within the above range.

In forming the first and second coating layers,
Since it is necessary to collide each particle powder in the state of primary particles, if each particle powder material to be used cannot be obtained in the state of primary particles, in advance, according to a conventional method, use a high-speed stirrer equipped with a rotary blade. It is necessary to put them in a state of primary particles (one particle is in a disjointed state).

According to what has been described above, it can be guaranteed that highly sensitive fluorescent magnetic powder can be manufactured at low cost.

[0037]

The fluorescent magnetic powder for magnetic particle flaw detection test according to the present invention comprises Fe ₃ O ₄ particles having a black surface color and γ
A first coating layer made of white inorganic particles is formed on the surface of magnetically conductive iron oxide particles such as —Fe ₂ O ₃ particles, and a second coating layer made of fluorescent coloring material is formed on the surface of the white coating layer. Therefore, under the irradiation of ultraviolet rays, the fluorescent coloring material located on the outermost surface has a white surface of high reflectance on the lower surface, so that its fluorescent function is fully exerted. Even if the amount of coloring material is relatively small,
Sufficient fluorescent brightness can be obtained. In fact, as shown in Examples described later, when the white coating layer is present, the amount is about 1/5 of that in the case where the white coating layer is not present (Example 3, Comparative Example 2 and Example 10, With the fluorescent coloring material of Comparative Example 4), almost the same fluorescent brightness is obtained.

Since the first coating layer composed of white inorganic particles forms a white surface having high reflectance on the surface of the magnetically conductive iron oxide particles, it may be a thin layer. It can be formed by using it, and in combination with the fact that a small amount of fluorescent coloring material is required by the above-mentioned action,
The decrease in magnetic sensitivity due to the coating layer is practically negligible, as shown in Examples below.

Next, since the method for producing the fluorescent magnetic powder for the magnetic particle flaw detection test according to the present invention is based on the mechanochemical reaction, each particle of the above magnetic iron oxide particle powder without using a binder such as a synthetic resin. It is possible to efficiently fix each particle of the white inorganic particle powder to the surface to form the first coating layer, and to efficiently fix each particle of the fluorescent colorant particle powder to the surface of the first coating layer. Since the adhered substances are hardly peeled off or fallen off, the target substance can be obtained in good yield.

[0040]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples. In addition, the whiteness, the fluorescence brightness, and the magnetic sensitivity in each of the examples and the comparative examples are measured by the following respective methods, and the flaw detection performance is evaluated by performing the following magnetic particle flaw detection test method.

Whiteness: Measured using a photoelectric gloss meter (manufactured by Tokyo Denshoku Co., Ltd.).

Fluorescent brightness: A Yagi microfluorimeter (manufactured by Kotaki Seisakusho Co., Ltd.) was used, and the fluorescent magnetic powder (Examples 1 to 4 and Comparative Example 1, as a reference) was used as a reference for the powder brightness measuring cell of the fluorescent photometer. 2 was used as a reference, the fluorescent magnetic powder of Comparative Example 1 was used as a reference, the fluorescent magnetic powder of Comparative Example 1 was used as a reference in Examples 5 to 7, and the fluorescent magnetic powder of Comparative Example 3 was used as a reference in Examples 8 to 10 and Comparative Examples 3 and 4). Filling, adjusting the deflection of the meter needle at this time to 100% and placing it, then replacing the reference fluorescent magnetic powder, filling the measuring cell with the fluorescent magnetic powder to be measured, and instructing the meter needle at that time (%) Was read and displayed as relative%.

Magnetic sensitivity: A magnetic sensitivity measuring instrument having the structure shown in FIG. 1 was manufactured, and the fluorescent magnetic powder to be measured was tapped into a glass cell for measurement having a volume of 45 ml and filled up to the marked line. Ammeter 4 scale of 0.3A
After reading the scale of the voltmeter 3 according to, the glass cell for measurement filled with the fluorescent magnetic powder is inserted into the coil 5, the scale of the ammeter 4 is adjusted to 0.3, and the scale of the voltmeter 3 is read. The value obtained by subtracting the voltage value before insertion from the voltage value after insertion is displayed.

Flaw detection performance: Examples 1 to 10 and Comparative Examples 1 to
For each of the fluorescent magnetic powders of No. 6, the following magnetic powder flaw detection test method was carried out.

A magnetic powder solution prepared by dispersing 2 g of fluorescent magnetic powder per 1 liter of water using a dispersant (using 20 ml of a nonionic surfactant per 1 liter of water) was prepared and was electrified by an axial electrification method (D
C 1000A) The magnetic powder liquid was sprayed on the surface of the square billet made of steel, and the sprayed surface was visually observed under irradiation of an ultraviolet lamp (black light) in a dark place, and the scratch depth existing on the surface of the square billet was observed. When the 0.1 mm aperture defect part is clearly indicated by the fluorescent indication pattern, it is "○", when it is indicated by the clearer and clear fluorescent indication pattern, it is "◎", and the fluorescent indication pattern is unclear. The case where the presence of the opening defect portion could not be confirmed was evaluated as "x".

Examples 1 to 4, Comparative Examples 1 and 2 Fe ₃ O ₄ particle powder having an average particle size of 3 μm (Tarox B
L-SP: trade name: made by Titanium Industry Co., Ltd.), titanium oxide particle powder with an average particle size of 0.03 μm and whiteness of 95% (Taipaque TTO-55 (A): trade name: made by Ishihara Sangyo Co., Ltd.) and average. Table 1 shows fluorescent pigment particle powder (Lumogen Yellow: trade name: manufactured by BASF) having a particle diameter of 0.1 μm.
4 types of fluorescent magnetic powders for magnetic particle flaw detection test according to the present invention were manufactured by the following operations.

Crusher equipped with rotary wings (Cosmomizer:
(Trade name: Nara Machinery Co., Ltd.), each predetermined amount of the above Fe ₃ O ₄ particle powder and the above titanium oxide particle powder was charged, and the powder was converted into primary particles at a blade tip peripheral speed of 100 m / sec and a rotation speed of 6000 rpm. Particle velocity of about 10 in the gas phase
The mechanochemical reaction was performed by accelerating to 0 m / sec and colliding the particles for 3 minutes.

Then, the particle powder of the above-mentioned Fe ₃ O ₄ particle powder, in which the respective particles of the above-mentioned titanium oxide particle powder adhere to the surface of each particle, and the first coating layer is formed, and the above-mentioned fluorescent pigment particle powder. Is charged into the crusher, and at the same blade tip peripheral speed and rotation speed as above, the powder is accelerated in the gas phase in the form of primary particles to a particle speed of about 100 m / sec to cause particles to separate from each other. Particle powder in which each particle of the fluorescent pigment particle powder adheres to the surface of the first coating layer to form a second coating layer by performing a mechanochemical reaction by colliding for a minute (the magnetic particle flaw detection test according to the present invention To obtain a fluorescent magnetic powder).

It should be noted that, during the whole operation, only slight separation and detachment of the core particles and the sub-particles was observed, so that the obtained particle powder maintains the blending ratio of each prescribed material. Can be estimated.

For comparison, the Fe ₃ O ₄ particle powder and the fluorescent pigment particle powder were used in the formulation shown in Table 1, and two types of comparative fluorescent magnetic powders were produced by the following procedure.

A predetermined amount of the Fe ₃ O ₄ particle powder and the fluorescent pigment particle powder was charged into the pulverizer, and the powder was vaporized in the state of primary particles at the same blade tip peripheral speed and rotation speed as described above. In the phase, the particle velocity is accelerated to about 100 m / sec and the particles are collided with each other for 2 minutes to cause a mechanochemical reaction, so that each particle of the fluorescent pigment particle powder adheres to the surface of each particle of the Fe ₃ O ₄ particle powder. Particle powder (comparative fluorescent magnetic powder) was obtained. Also in this case, the separation between the core particles and the child particles
Since only a slight dropout was observed, it can be inferred that the obtained particle powder maintained the compounding ratio of both the prescribed materials.

Table 1 shows the fluorescent brightness, magnetic sensitivity, and flaw detection performance of the four types of magnetic flux particles for the flaw detection test according to the present invention and the two types of the comparative magnetic flux particles for comparison.

[0053]

[Table 1]

Examples 5 to 7 Fe ₃ O ₄ particle powder same as in the above-mentioned Examples, average particle diameter of 0.
Kaolin having a whiteness of 8% and a whiteness of 88% (Satinton No5: trade name: manufactured by Tsuchiya Kaolin Kogyo Co., Ltd.) and the same fluorescent pigment particle powder as in the above-mentioned Examples were used in the formulations shown in Table 2 to detect three types of magnetic particle flaws according to the present invention. The test fluorescent magnetic powder was manufactured by the same operation and the same conditions as those in the above-mentioned Examples.

Note that, during the whole operation, only slight separation and detachment of the core particles and the sub-particles was observed, so that the obtained fluorescent magnetic powder for magnetic particle flaw detection test according to the present invention is a mixture of the prescribed materials. It can be estimated that the ratio is maintained.

Table 2 shows the fluorescent brightness, the magnetic sensitivity, and the flaw detection performance of the three types of the fluorescent magnetic powder for flaw detection test according to the present invention.

[0057]

[Table 2]

Examples 8 to 10 and Comparative Examples 3 and 4 γ-Fe ₂ O ₃ particle powder (γ-50 having an average particle diameter of 2 μm)
0: trade name: manufactured by Titanium Industry Co., Ltd.), the same titanium oxide particle powder as in Examples 1 to 4 and the same fluorescent pigment particle powder as in Examples 1 to 4 are used in the formulation of Table 3, and three kinds of the present invention are related Fluorescent magnetic powder for a magnetic particle flaw detection test was manufactured by the same operation and the same acceleration conditions as in Examples 1 to 4.

Note that, during the whole operation, since the separation and detachment of the core particles and the sub-particles was observed only slightly, the obtained fluorescent magnetic powder for magnetic particle flaw detection test according to the present invention was blended with each of the prescribed materials. It can be estimated that the ratio is maintained.

For comparison, the above-mentioned γ-Fe ₂ O ₃ particle powder and the above-mentioned fluorescent pigment particle powder were used in the formulation shown in Table 3, and two kinds of comparative fluorescent magnetic powders were used in the same operation and the same acceleration as in Comparative Examples 1 and 2. It was manufactured according to the conditions. Also in this case, since the separation and drop-off between the core particles and the child particles was only slightly observed,
It can be inferred that the obtained comparative fluorescent magnetic powder maintains the blending ratio of both the prescribed materials.

Table 3 shows the fluorescent brightness, the magnetic sensitivity, and the flaw detection performance of the three types of the magnetic flaw detection test fluorescent magnetic powders according to the present invention and the two types of comparative fluorescent magnetic powders obtained here.

[0062]

[Table 3]

[0063]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a high fluorescent brightness even if the compounding ratio of the fluorescent brightness coloring material, which is the most expensive in the material cost of the fluorescent magnetic powder for magnetic particle flaw detection test, is reduced, so that the cost is low.
Moreover, highly sensitive fluorescent magnetic powder can be provided.

Further, according to the present invention, each particle of the magnetically conductive iron oxide particle powder is used as a core particle by the mechanochemical reaction, and a white inorganic particle powder and a fluorescent material are used on the surface of the particle without using a binder made of synthetic resin. Since each particle of the coloring material particle powder is fixed as a child particle, the target fluorescent magnetic powder can be efficiently manufactured.

Therefore, the present invention satisfies the demands of fluorescent magnetic powder users for magnetic particle flaw detection tests, such as steel manufacturers and automobile manufacturers, and it can be said that its industrial applicability is very high.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a magnetic sensitivity measuring device used in the present invention.

[Explanation of symbols]

1 sliderac 2 transformer 3 voltmeter 4 ammeter 5 coil

Claims (2)

[Claims] 1. A magnetic iron oxide particle having an average particle diameter of 2 to 5 μm, 60 to 90% by weight, white inorganic particles having an average particle diameter of 0.02 to 1 μm, 3 to 20% by weight, and an average particle diameter of 0.1 to 0.
2 to 10% by weight of fluorescent colorant particles of 5 μm are mixed, and the white inorganic particles are fixed to the surface of the magnetically conductive iron oxide particles as a first coating layer by a mechanochemical reaction, A fluorescent magnetic powder for magnetic particle flaw detection test, wherein the fluorescent colorant particles are fixed as a second coating layer by a mechanochemical reaction. 2. A magnetic conductive iron oxide particle powder having an average particle diameter of 2 to 5 μm, 60 to 90% by weight, and an average particle diameter of 0.02 to 1 μm.
3 to 20% by weight of the white inorganic particle powder are mixed in the state of primary particles, and the mixed powder in the gas phase has a particle velocity of 60 to 1
By accelerating at 60 m / sec and causing the particles to collide with each other to perform a mechanochemical reaction, each particle of the white inorganic particle powder is fixed to the surface of each particle of the magnetically conductive iron oxide particle powder to form the first coating layer. Then, 2 to 10% by weight of fluorescent colorant particle powder having an average particle diameter of 0.1 to 0.5 μm is added to the magnetically conductive iron oxide particle powder on which the first coating layer is formed in the form of primary particles. Then, the mixed powder is accelerated in the gas phase to a particle velocity of 60 to 160 m / sec to cause particles to collide with each other to cause a mechanochemical reaction, and thereby the fluorescent colorant particle powder is applied to the surface of the first coating layer. A method for producing a fluorescent magnetic powder for a magnetic particle flaw detection test, which comprises fixing the respective particles to form a second coating layer.