JPH07111420B2 - Manufacturing method of colored magnetic powder for magnetic particle inspection - Google Patents

Description

The present invention relates to a method for producing a colored magnetic powder for magnetic particle flaw detection.

[Conventional technology]

Magnetic particle flaw detection, which is a type of non-destructive inspection method for magnetizable inspected objects such as steel, is standardized in JIS GO 565-1974. Then, in this flaw detection method, pure iron particle powder, ferrosoferric oxide particle powder, and stainless steel particle powder (these are referred to as “magnetic particles”), which are magnetically conductive particle powders, have white, red, or What is colored with a coloring material such as a pigment or dye exhibiting a yellow color or a fluorescent pigment that is excited by irradiation with ultraviolet rays and emits a yellow to yellow green color (these are referred to as "colored magnetic powder") is used. This is well known.

The colored magnetic powders are roughly classified into those in which a coloring material is fixed to a magnetic powder by using a synthetic resin as a binding material, and those in which the coloring material is directly fixed to a magnetic powder without using a binding material.

A typical method for producing colored magnetic powder without using the latter binder is
It is called the "adsorption method" disclosed in Japanese Examined Patent Publication (Kokoku) No. Sho 48-30223, which requires the use of an intermediate of a specific organic fluorescent dye, and is at the ortho position. Magnetic powder is dispersed and placed in a hydroalcoholic solution in which an aromatic aldehyde having a hydroxyl group is dissolved, and hydrazine is added to this to precipitate a fluorescent dye having a hydroxyl group at the ortho position of the azomethine bond in the liquid. In this method, the fluorescent dye is adsorbed on the surface of each particle of the magnetic powder, and then washed, dried and dried to obtain a colored magnetic powder having a required particle size.

[Problems to be solved by the invention]

The present invention belongs to a method for producing a colored magnetic powder in which a coloring material is directly fixed to a magnetic powder without using a binder, and the selection range of the coloring material inherent in the "adsorption method" is significantly limited. The technical problem is to solve the above problem and the problem that the target magnetic powder is limited to those having a relatively small average particle size (average particle size of about 8 microns or less).

Further, the present invention has a technical problem to produce a colored magnetic powder in which a coloring material is more firmly fixed to the magnetic powder, as compared with the “adsorption method”.

[Means for solving problems]

The present inventor has achieved the above technical problem by taking the following technical means.

That is, 40 to 98 parts of pure iron particle powder, ferrosoferric oxide particle powder or stainless steel particle powder having an average particle size of 1 micron to 10 micron as a magnetic powder and a coloring material Using 2 to 60 parts of an organic pigment particle powder having an average particle size of at least 1/10 or less of the average particle size of the magnetic powder to be colored, and mixing both powders in the state of primary particles, Particle velocity of powder in gas phase 60-160m / s
A method for producing colored magnetic powder for magnetic particle flaw detection, which comprises fixing the coloring material to each particle surface of the magnetic powder by a mechanochemical reaction by accelerating to ec and colliding the particles for 1 to 3 minutes.

The magnetic powder used in the method of the present invention is a pure iron particle powder, a ferrosoferric oxide particle powder or a stainless steel particle powder having an average particle size within the range of 1 to 10 microns. All of these are commonly used for magnetic particle flaw detection, and there are commercial products, and those having a desired average particle size are easily available.

When manufacturing colored magnetic powders used for precise magnetic particle flaw detection, magnetic powders with a required average particle size within the range of average particle size 1 micron to average particle size 5 microns should be selected. When the colored magnetic powder used for magnetic particle flaw detection is manufactured, a magnetic powder having a required average particle size within the range of 6 to 10 μm may be selected.

When 40 to 98 parts of the above magnetic powder is used to detect flaws in the magnetic powder using the obtained colored magnetic powder, if the amount is 40 parts or less, the ability to collect and adhere to defective parts (magnetic sensitivity) will be small and accurate. This is because it is difficult to obtain a satisfactory flaw detection result, and when the amount is 98 parts or more, the amount of the coloring material becomes too small and a sufficient coloring effect cannot be obtained.

The coloring material used in the method of the present invention must be an organic pigment particle powder having an average particle size of at least 1/10 or less of the average particle size of the magnetic powder to be colored. More specifically, for example, when a magnetic powder having an average particle size of 1 micron is used, an organic pigment particle powder having an average particle size of 0.1 micron or less is used, and when a magnetic powder having an average particle size of 10 microns is used, an average particle size of 1 micron is used. The following organic dye particle powder is used.
When using an organic pigment particle powder having an average particle diameter of 1/10 or more of the average particle diameter of the magnetic powder to be colored, it becomes extremely difficult to cause a mechanochemical reaction, and It is not possible to firmly fix the organic dye particle powder, but when it is 1/10 or less, as described later, it is possible to firmly fix the organic dye particle powder in almost a film shape on each particle surface of the magnetic powder. . It is preferable to use an organic dye particle powder having an average particle size as small as possible than the average particle size of the magnetic powder to be colored.

The organic pigment particle powder is selected from among commercially available powdered organic pigments, organic dyes or organic fluorescent pigments having a required average particle diameter, or commercially available powdered organic pigments, An organic dye or an organic fluorescent pigment may be crushed to a required average particle size before use.

The use of 2 to 60 parts of the above-mentioned organic dye particle powder means that the coloring effect is low in the case of less than 2 parts in performing magnetic particle flaw detection using the obtained colored magnetic powder, and the organic fluorescent dye particle powder is used. This is because it is difficult to obtain a sufficient fluorescent indication even when observing under UV irradiation. The upper limit is relatively determined from the minimum required amount of magnetic powder.

The method of the present invention is to firmly fix the organic dye particle powder as described above to the surface of each particle of the magnetic powder as described above by a mechanochemical reaction. For this purpose, both powders are in the state of primary particles. Two steps are required: a step of forming the mixed powder mixed in step 1) and a step of causing a mechanochemical reaction in the mixed powder.

In the previous step, for example, if a high-speed stirrer equipped with a well-known rotary blade is used and the powder is vigorously mixed while mainly applying a shearing force, each particle becomes a primary particle. Usually, a magnetic powder having a required average particle size within the range of commercially available average particle size 1 micron to average particle size 10 microns and commercially available average particle size 0.
Organic pigment particle powder having a required average particle size within the range of 1 micron to 1 micron is a fine particle powder in the unit of micron, so one particle is one primary particle Although not in a state, it is in an agglomerated state, but both of these powders are put into a blade with a high speed agitator equipped with a rotating blade, the peripheral speed of the blade tip is 4 to 10 m / sec, the rotation speed is 1000 to 350.
If the mixture is stirred under the condition of 0 RPM for 3 to 5 minutes, it is possible to easily form a sufficiently mixed mixture in the form of primary particles.

In the subsequent step, using a known high-speed rotating mill or jet mill, the powder is accelerated in the gas phase to a particle velocity of 60 to 160 m / sec and the particles are allowed to collide for 1 to 3 minutes. The particles become particles, and the organic dye particles become firmly attached to the surface as child particles. If the particle velocity is not accelerated to 60 m / sec or more, it is not possible to obtain the mechanical and thermal energy required to fix the child particles to the core particles, but 60 m / se
If the particles are made to collide with each other by accelerating to more than c, each particle of the magnetic powder can be used as a core particle, and the pigment particles, which are child particles, can be almost fixed to the surface in a film form.
The larger the particle velocity, the stronger the adhesion, but for practical purposes up to about 160 m / sec is sufficient. The time for the particles to collide with each other must be at least 1 minute or more at a particle velocity of 60 to 160 m / sec. The longer the time, the stronger the adhesion will be. Is enough. Particle velocity 1 to 60 to 160 m / sec
After colliding the particles with each other for 3 minutes, the acceleration is stopped to obtain colored magnetic powder in which each particle of the magnetic powder is used as a core particle and the organic dye particles are uniformly and firmly adhered to the surface of the particle. One colored magnetic powder is in a disjointed state.

[Action]

Using the magnetic powder as described above and the organic dye particle powder as described above, both powders are 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 msec to make particles 1 When they are collided for ~ 3 minutes, mechanical and thermal energy generated from impact force and frictional force at the time of collision causes mechanochemical reaction between magnetic powder particles as core particles and organic pigment particles as child particles. Then, the organic dye particles, which are child particles, firmly adhere to the surface of each magnetic powder particle, which is a core particle.

The present inventor has confirmed by microscopic observation that the organic pigment particles adhere to the surface of each magnetic powder particle in a substantially film-like manner, and that some of the used organic pigment particles have melted.

〔Example〕

The method of the present invention will be described in more detail with reference to examples. still,
"Parts" means "parts by weight".

Example 1. Pure iron particle powder 95 having an average particle size of 4 microns commercially available as magnetic powder 95
Part and colorant commercially available Lumogen Brilliant Yellow with an average particle size of 0.5 micron (Product name: Fluorescent dye: Melting point 230
5 parts) was mixed for 4 minutes at a tip speed of a stirring blade of 8 m / sec and a rotation speed of 1200 RPM using a high-speed stirring mixer to obtain a mixed powder.

Next, the mixed powder is accelerated to a particle velocity of 100 m / sec using a high-speed rotary mill, and the particles are collided with each other for 3 minutes to give a colored magnetic powder having an average particle size of 5 microns (in the industry, "fluorescent magnetic powder" It is called.) I got 98 parts.

The colored magnetic powder was taken out from the high-speed rotary mill and used as it was for the following magnetic particle flaw detection.

A magnetic powder liquid prepared by dispersing 0.5 g of the above-mentioned colored magnetic powder per 1 water using a dispersant (using 20 ml of surfactant per 1 water) was electrified (DC-1000A) by an axial electrification method to obtain an 80 mm square billet. When sprayed on the surface and irradiated with ultraviolet light using a black light on the sprayed surface and observed in a dark place, the defect part with a depth of 0.15 mm present on the surface of the square billet has a defect indicator pattern showing yellow-green fluorescence. It was confirmed that it was clearly instructed. This flaw detection result shows that the peeling and dropping of the coloring material hardly occurred.

Example 2. Pure iron particle powder 90 having an average particle size of 10 microns commercially available as magnetic powder
Parts and 10 parts of commercially available permanent red 4R (trade name: red pigment: melting point 280 ° C) having an average particle size of 0.6 microns as a coloring material, using a high-speed stirring mixer, a stirring blade tip speed of 8 m
/ sec, rotation speed 1200 RPM for 4 minutes to obtain a mixed powder.

Next, the above-mentioned mixed powder was accelerated to a particle velocity of 130 m / sec by using a high-speed rotating mill, and the particles were collided with each other for 3 minutes to obtain 98 parts of a colored magnetic powder having an average particle diameter of 12 microns.

The colored magnetic powder was taken out from the high-speed rotary mill and used as it was for the following magnetic particle flaw detection.

The surface of a 80 mm square billet in which 2 g of the above colored magnetic powder per 1 water is dispersed with a dispersant (use 20 ml of surfactant per 1 water) and the magnetic powder liquid is energized (DC-1000A) by the axial energization method. It was confirmed that the defect part with a depth of 0.15 mm existing on the surface of the square billet was clearly indicated by the defect indicating pattern showing red color when it was sprayed on and the surface was observed under visible light. . This flaw detection result shows that the peeling and dropping of the coloring material hardly occurred.

〔effect〕

According to the method of the present invention, a colored magnetic powder in which a coloring material is directly fixed to the magnetic powder without using a synthetic resin binder can be produced in the gas phase with high efficiency and high yield.

Moreover, according to the method of the present invention, the selection range of the coloring material is wide, and it is possible to use commercially available organic pigments, organic dyes, and organic fluorescent pigments, and also to compare the average particle diameters of the magnetic powders to be colored. It is possible to freely select from small to relatively large ones.

Furthermore, according to the method of the present invention, colored magnetic powder in which the coloring material is firmly fixed to the magnetic powder can be obtained without using a synthetic resin binder.

Claims (2)

[Claims] 1. Pure iron particle powder, ferrosoferric oxide particle powder or stainless steel particle powder 40 to 98 parts having an average particle diameter of 1 micron to 10 micron as a magnetic powder. Using 2 to 60 parts of an organic pigment particle powder having an average particle size of at least 1/10 or less of the average particle size of the magnetic powder to be colored as a coloring material, both powders are mixed in a primary particle state. , The mixed powder in the gas phase particle velocity 60 ~
A method for producing a colored magnetic powder for magnetic particle flaw detection, characterized in that the coloring material is fixed to each particle surface of the magnetic powder by a mechanochemical reaction by accelerating the particles to 160 m / sec and colliding the particles for 1 to 3 minutes. . 2. The method for producing a colored magnetic powder for magnetic particle flaw detection according to claim 1, wherein the organic dye particle powder is an organic fluorescent dye particle powder.