JP2006169584A - Thermal-sprayed film of iron nitride and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an iron nitride film formed through a thermal spraying process, and to provide a manufacturing method therefor. <P>SOLUTION: The thermal-sprayed film mainly containing iron nitride is formed on a substrate, by charging iron in thermal plasma while contacting a strongly luminant part of the thermal plasma containing nitrogen with the substrate, in the thermal spraying process. In the above step, it is recommended to form the thermal-sprayed film while keeping the temperature at the part to be film-formed to the decomposition temperature of iron nitride or lower, by controlling the temperature of the substrate. Furthermore, it is possible to form a dense thermal-sprayed film with a high content ratio of iron nitride even when iron remains in a gap between iron nitride particles in the thermal-sprayed film, by proceeding nitriding of iron through irradiating the substrate with thermal plasma without charging iron while contacting the strongly luminant part of the thermal plasma containing nitrogen with the substrate, and keeping the temperature at the part to be film-formed to the decomposition temperature of iron nitride or lower. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a cutting tool as a structural material that requires mechanical properties such as corrosion resistance and wear resistance, and an iron nitride sprayed film that is suitable for coating parts that require mechanical properties, and a member coated therewith And a manufacturing method thereof.

Since iron nitride has physical properties excellent in corrosion resistance and wear resistance, it has been conventionally used for surface modification of devices and parts that require corrosion resistance and surface hardening in tool steel and the like. Since iron nitride is a material having such excellent physical properties, there is a demand for a technique for forming a thick film of iron nitride on a metal, oxide, or ceramic base material for wider use. It is growing.

Examples of iron nitride films that have been reported so far are only thin films by sputtering or CVD (see, for example, Patent Document 1 and Non-Patent Document 1). Further, high-purity films are obtained by sputtering or CVD, but the films obtained by these methods are thin films, and the corrosion resistance and wear resistance are not always sufficient.

On the other hand, a thermal spraying method is generally known as a method for forming a thick film of metal or ceramic at high speed. The thermal spraying method is mainly a method in which a thermal spray raw material is melted and the molten thermal spray raw material is deposited on a substrate at high speed. If the thermal spraying method is used, it is generally possible to produce a thick film of several μm to several mm. However, when non-oxides such as nitrides and carbides are formed by thermal spraying, many of them are decomposed before being melted, so that there is a problem that film formation cannot be performed.

However, no attempt has been made to form an iron nitride film by thermal spraying. For example, it has been attempted to form iron nitride by atmospheric pressure tunneling plasma spraying using iron powder as a raw material and nitrogen as a plasma gas (see, for example, Non-Patent Document 2). However, the report reports that iron oxide was formed and no formation of iron nitride was observed.

JP 09-69461 A S. Yu. Grachev, D.C. M.M. Borsa and D.C. O. Boerma, Surface Science, Vol. 516, 159-168 (2002) Niizuma, Mikawa, Kobayashi, Plasma Applied Science, Vol 9, 136-138 (2001)

Conventionally, in the thermal spraying method used to obtain a thick film, it has been difficult to obtain a thick film made only of iron nitride or having a high ratio of iron nitride. It was not possible to obtain a thick film capable of exhibiting the above or the like, or a member coated with such a thick film.

The object of the present invention is to provide a novel method for reactive plasma spraying of iron, and to cover a dense sprayed film consisting of only iron nitride, or a dense sprayed film consisting of only iron nitride and iron with a high iron nitride ratio. It is to provide a simple manufacturing method at the same time of providing the member.

As a result of intensive studies in view of the above situation, the present inventors have used a thermal plasma containing nitrogen, and the distance at which the base material is sufficiently in contact with the thermal plasma, that is, the high brightness of the thermal plasma. Under conditions that allow contact with various parts, plasma spraying is performed at a temperature equal to or higher than the melting point of iron while iron is put into the thermal plasma, and the temperature of the film forming site is kept below the decomposition temperature of iron nitride, thereby providing iron nitride on the substrate. It has been found that a high thermal spray content and a dense sprayed film can be obtained. In addition, in the sprayed film obtained by the method of the present invention, even if iron remains in the gaps between the iron nitride particles in the sprayed film, iron is introduced while bringing the bright part of the thermal plasma containing nitrogen into contact with the substrate. Without irradiating it, and keeping the temperature of the film formation site below the decomposition temperature of iron nitride, the nitriding of iron can be advanced and a dense thermal sprayed film with a high ratio of iron nitride can be obtained. I found it. Moreover, in the method of this invention, it discovered that nitriding was accelerated | stimulated by adding hydrogen to nitrogen essential as plasma gas. Furthermore, the member which coat | covered the base material with the thermal spray film of the iron nitride obtained by the method of this invention discovered that it was excellent in hardness, abrasion resistance, corrosion resistance, etc., and came to complete this invention.

The iron nitride sprayed film, the member coated with the iron nitride sprayed film, and the manufacturing method thereof have the following effects.
The sprayed coating of the present invention has a high ratio of iron nitride and is a dense film made only of iron nitride and iron. Therefore, the sprayed coating has high hardness and can exhibit high wear resistance and corrosion resistance when coated on a member.
The manufacturing method of the thermal spray film of the present invention is simple because the dense thermal spray film mainly composed of iron nitride can be manufactured only by the thermal spraying method.

The iron nitride sprayed film of the present invention will be described.

The iron nitride sprayed film of the present invention is a thick film formed by a spraying method, and is different from a thin film obtained by a conventional sputtering method or CVD method. The film thickness is preferably 1 μm or more and 3 mm or less, and more preferably 100 μm or more and 1 mm or less. When the film is thinner than 1 μm, there is a problem in durability due to wear or the like. On the other hand, a thickness exceeding 3 mm is not generally required in the technical field using the film of the present invention and is not economical.

The iron nitride sprayed film of the present invention is a film made of iron nitride and iron, and the iron nitride content is preferably high. The reason is that the higher the iron nitride content, the higher the effect of improving corrosion resistance, wear resistance and hardness, so that high performance is exhibited when used in application fields that require those characteristics, such as cutting tools. Because.

The iron nitride content is preferably 25 mol% or more and 100 mol% or less, preferably 40 mol% or more.
When the content of iron nitride is less than 25 mol%, the amount of iron present in the film increases, which is not preferable for achieving the target performance of the present invention. On the other hand, if the sprayed film is formed only from iron nitride, the content is 100 mol%.

The thermal sprayed film of the present invention is a film mainly composed of iron nitride, and is a film made of iron as a component other than iron nitride.
However, those having impurities in these raw materials and having the same performance as the iron nitride film of the present invention due to the impurities are not excluded from the present invention.

Furthermore, the film of the present invention does not exclude the film containing iron oxide formed by oxidation in the air, and the film containing iron oxide that is naturally generated within the range normally considered is also within the scope of the present invention.

The structure of the thermal sprayed film of the present invention is not particularly limited, and can take any morphology from a dense film to a porous film. However, for the purpose of the present invention, that is, applications requiring corrosion resistance, wear resistance, etc., a dense film having no pores is particularly preferable.

Furthermore, this invention provides the member which formed the above-mentioned iron nitride sprayed film on the base material. A member is not specifically limited, Glass, ceramics, a metal, etc. can be utilized.

Next, the manufacturing method of the sprayed film of this invention is demonstrated.

A method for producing a sprayed film mainly composed of iron nitride according to the present invention will be described with reference to an example of the apparatus shown in FIGS.

In the method of the present invention, a substrate is attached to a device having a portion for generating thermal plasma and a portion for holding the substrate to form a film.

The pressure in the thermal spraying conditions of the present invention is not particularly limited, and can be performed under pressure, normal pressure, or reduced pressure. In the case of normal pressure, it may be performed at atmospheric pressure. However, in the case of reducing pressure, for example, after the thermal spraying container in FIG. 1 is evacuated to 0.5 Torr or less by the rotary pump 107, the quartz tube 113 of the thermal plasma source is used. For example, a film can be formed at a pressure of 20 to 150 Torr by introducing a sheath gas 108 such as argon and a plasma gas 109 such as nitrogen and argon for protection.

FIG. 2 shows an example of an apparatus for spraying at atmospheric pressure. In an apparatus having a part for generating thermal plasma at atmospheric pressure and a part for holding the substrate 25, a plasma gas such as nitrogen and hydrogen is introduced from the plasma gas line 22 and a voltage is applied between the cathode 20 and the anode 21. The thermal plasma 28 can be generated by a direct current arc.

Although the base material which forms the sprayed film used by this invention is not specifically limited, For example, metal base materials, such as stainless steel and carbon steel, graphite, quartz, ceramics, etc. can be used as the base material 101 of FIG. In order to improve the adhesion to the sprayed film, the substrate used is preferably mounted on the substrate holder 102 in the vacuum chamber 103 after the surface is roughened by a blast method or the like.

Next, the thermal spraying method of the present invention uses thermal plasma. Although the generation method of thermal plasma is not limited, for example, it can be generated by high frequency, direct current arc, alternating current arc, or the like. FIG. 1 illustrates a method of generating a thermal plasma 104 by applying a high frequency to the high frequency coil 110.

The method of the present invention is characterized by performing thermal spraying while bringing a bright portion of thermal plasma containing nitrogen into contact with a substrate. The thermal plasma is composed of a bright portion at the center and a low brightness portion around it. In the present invention, thermal spraying is performed on the substrate by spraying under the condition that the bright portion of the thermal plasma is in contact with the substrate. Nitriding of the film can be promoted. The bright portion of the thermal plasma referred to here is a portion of the gas stream that is generated by gas discharge by the above-described means and is at least partially ionized and has a high temperature of several thousand to tens of thousands of degrees. In order to bring the bright part of the thermal plasma into contact with the base material, for example, by visually observing the state of the thermal plasma using sunglasses, the distance between the plasma generation part and the base material holding part can be adjusted.
For example, in the case of FIG. 1, the distance (spraying distance) 106 between the outlet of the thermal plasma 104 and the base material 101 is adjusted by the spacer 105 at the bottom of the base material holder 102, and the bright part of the thermal plasma touches the base material. Thermal spray with. In order to develop such a state, in the case of the apparatus shown in FIG. 1, it is preferable to set the spraying distance 106 to about 10 to 100 mm, particularly 20 mm to 60 mm. By shortening the spraying distance, the bright part of the thermal plasma can be sufficiently brought into contact with the base material and the nitriding of the iron component can be advanced, and a dense film can be obtained.

In the case of irradiating the substrate with thermal plasma at atmospheric pressure shown in FIG. 2, the distance (spraying distance) 24 between the outlet of the thermal plasma and the substrate 25 (spraying distance) is adjusted by the movement of the substrate. Thermal spraying may be performed in a state where a bright portion of thermal plasma is in contact with a certain substrate. In this case, the spray distance 24 is preferably about 10 to 50 mm, particularly preferably 20 to 40 mm. By shortening the spraying distance, the bright part of the thermal plasma can be sufficiently brought into contact with the substrate, the nitriding of the iron component can be promoted, and a dense film can be obtained.

The position of the base material in the thermal spraying of the present invention may be a position where the thermal plasma is irradiated, that is, a position where a portion where the thermal spray film is formed contacts a bright portion of the thermal plasma. Although the base material may be fixed, it is preferable that the base material 101 or 25 is moved back and forth and left and right, and the whole base material is irradiated with thermal plasma to form a uniform film. This movement of the base material may be performed under the conditions of the present invention at the time of film formation on the base material, that is, a condition in which a bright portion of the thermal plasma is in contact with the sprayed portion, for example, 10 to 100 mm at the spraying distance 106 in FIG. The range which can be maintained can be illustrated.

As described above, the distance between the thermal plasma generation source where the bright portion of the thermal plasma contacts the substrate and the substrate differs depending on the method of generating the thermal plasma. In the present invention, it is only necessary that the bright portion of the thermal plasma is in contact with the substrate, and the distance between the thermal plasma generation source and the substrate is not limited.

Furthermore, in the present invention, while bringing a bright portion of the thermal plasma containing nitrogen into contact with the substrate, for example, in the method of FIG. A thermal sprayed film is formed. At this time, even if the temperature of the part where the bright part of the thermal plasma is in contact with the surface of the film being formed is higher than the decomposition temperature of iron nitride, the temperature of the film forming part is set to iron nitride. It is a feature of the present invention that the base material temperature is controlled to be equal to or lower than the decomposition temperature of 670 ° C. In order to control the temperature of the film formation site below the decomposition temperature of iron nitride, it is necessary to directly measure the temperature of the film formation site. It is considered that the temperature is measured directly under the substrate side, and it is practically difficult to measure the temperature of this part. It is exemplified that it can be substantially realized by controlling the decomposition temperature to be equal to or lower than the decomposition temperature.

For example, in the method of FIG. 1, the substrate 101 placed in contact with the substrate holder is cooled by water cooling the substrate holder 102, and the interface between the coating and the substrate becomes below the decomposition temperature of iron nitride. To control. Thus, by controlling the temperature of the substrate so that the interface between the coating and the substrate becomes lower than the decomposition temperature of iron nitride, the nitriding reaction of iron on the substrate is promoted, and the coating in the coating A dense thermal sprayed film of iron nitride is deposited without decomposition of the iron nitride film formed at the formation site.

In the present invention, in order to nitride iron, it is essential that the thermal plasma contains nitrogen. As the gas for forming the thermal plasma, a gas that improves the stability of the plasma, such as argon, may be added to nitrogen. However, when hydrogen is included, an oxide film on the iron surface in the film is removed and it is easy to nitride. ,preferable. Further, ammonia gas may be used as an alternative to the mixed gas of nitrogen and hydrogen.

The method of the present invention forms a sprayed film by introducing iron into a thermal plasma containing nitrogen. Examples of the shape of the iron to be charged include powder, pellets, and wires, but powder is particularly preferable. FIG. 1 illustrates a method for supplying iron in powder form. The carrier gas 112 is introduced into the powder supplier 111, iron powder is supplied, and the powder is supplied into a thermal plasma containing nitrogen. It is preferable that the supply rate of iron at this time is uniform.

When powder is used for the raw material iron in the present invention, it is preferable that the particle size of the powder is small because of high reactivity with thermal plasma containing nitrogen. On the other hand, if the particle size is too small, the fluidity is deteriorated and it is difficult to supply at a constant speed. Therefore, the average particle size of the raw iron powder is preferably 1 μm or more and 70 μm or less. The method for measuring the average particle size of the iron powder can be measured with a general particle size measuring device such as a light transmission type particle size distribution measuring device.

In the present invention, the thermal spray film obtained by the above-described thermal spraying is subsequently irradiated with thermal plasma containing nitrogen or nitrogen and hydrogen under conditions that bring the bright part of the thermal plasma into contact with the substrate, thereby remaining in the film. Iron can be nitrided to obtain a sprayed film having a particularly high iron nitride content. In this case, since the purpose of the thermal plasma irradiation is nitridation of iron remaining in the film, irradiation is performed without newly introducing raw material iron into the thermal plasma. Here, it is preferable that the temperature in the film and the interface between the film and the substrate in the substrate portion irradiated with the thermal plasma is not more than the decomposition temperature of iron nitride, that is, not more than 670 ° C., as described above.

The thermal spray film of the present invention can be formed into a thick film by repeatedly depositing many layers. For example, in the method of FIG. In this case, a single thermal spray layer is first deposited on the substrate under the conditions of the present invention, and before the next thermal spray layer is deposited, a thermal plasma irradiation process including nitrogen that does not supply raw material iron is performed. The nitridation of iron remaining in the film can be further promoted. Thereafter, the same operation is repeated, that is, by alternately repeating the thermal plasma supplied with the raw iron and the thermal plasma without supplying the raw iron, a sprayed film having a very high content of iron nitride can be obtained. Here, after depositing a plurality of sprayed layers by the method of the present invention, a finishing irradiation step may be performed by thermal plasma without supplying iron.

EXAMPLES Although this invention is demonstrated further in detail based on an Example, this invention is not limited only to these Examples.

Example 1
An iron nitride sprayed film was formed on a carbon steel base using the apparatus shown in FIG. A 15 mm square carbon steel substrate 101 having a roughened surface by blasting was mounted on a water-cooled substrate holder 102 in a vacuum chamber 103. The spraying distance 106 was adjusted in advance to 60 mm and then evacuated to 0.5 Torr or less by the rotary pump 107. Next, the sheath gas 108 is argon 10 L / min, the plasma gas 109 is argon 10 L / min, nitrogen 2 L / min is introduced to a pressure of 60 Torr, and a high frequency of 5 kW is applied to the high frequency coil 110 to generate thermal plasma. I let you.
The bright part of the thermal plasma generated under these conditions was in sufficient contact with the carbon steel substrate.
The substrate was placed in contact with the substrate holder, and the substrate holder was cooled by water cooling, thereby cooling the substrate. Thus, since the base material is cooled from the back surface, no preheating is performed.

Next, a fine powder feeder manufactured by Technoserve Co., Ltd. is used as the powder feeder 111, argon is introduced as a carrier gas 112 at a flow rate of 1 L / min, and an iron raw material powder having an average particle size of 40 μm is thermal plasma at about 1 g / min. Supplied in. Thermal spraying was repeated while moving the 15 mm square base material 101 back and forth and left and right at a speed of 40 mm / sec, and 10 thermal spray layers were uniformly deposited. The temperature of the portion irradiated with plasma during film formation was in the range of 1500 ° C. to 1700 ° C. as measured with a radiation thermometer. The substrate back surface temperature measured with the thermocouple 114 brought into contact with the substrate back surface was 200 ° C.

The obtained sprayed film had a thickness of about 300 μm. When the crystal structure was analyzed by X-ray diffraction, the peak intensities of Fe ₄ N and iron were observed. When the composition was analyzed by the fluorescent X-ray method, iron nitride was 41 mol% and iron was 59 mol%. Further, as a result of SEM observation of the cross section of the sprayed film, the film structure was dense.

Example 2
An iron nitride sprayed film was formed under the same conditions as in Example 1 except that the flow rate of nitrogen was 0.5 L / min and a high frequency of 3 kW was applied to the high frequency coil 110 to generate thermal plasma.
The substrate temperature during thermal spraying was in the same range as in Example 1.

The obtained sprayed film had a thickness of about 300 μm. When the crystal structure was analyzed by X-ray diffraction, the peak intensities of Fe ₄ N and iron were observed. Analysis of the composition by fluorescent X-ray analysis revealed that iron nitride was 29 mol% and iron was 71 mol%. Further, as a result of SEM observation of the cross section of the sprayed film, it was a dense film as in Example 1.

Example 3
A sprayed coating was produced in the same manner as in Example 1 except that hydrogen at a flow rate of 0.5 L / min was further added as the plasma gas.

The obtained sprayed film had a thickness of about 200 μm. When the crystal structure was analyzed by X-ray diffraction, the peak intensities of Fe ₄ N and iron were observed. Analysis of the composition by fluorescent X-ray analysis revealed that iron nitride was 53 mol% and iron was 47 mol%. Further, as a result of SEM observation of the cross section of the sprayed film, it was a dense film as in Example 1.

Comparative Example 1
An iron nitride sprayed film was formed under the same conditions as in Example 1 except that the base material holder 102 having no cooling function was mounted. The temperature of the portion irradiated with plasma during film formation was in the range of 1500 ° C. to 1700 ° C. as measured with a radiation thermometer. The substrate back surface temperature measured with the thermocouple 114 brought into contact with the substrate back surface was 900 ° C.

The obtained sprayed film had a thickness of about 300 μm. When the crystal structure was analyzed by X-ray diffraction, only the peak intensity of iron was observed, and no iron nitride was produced.

Comparative Example 2
A sprayed coating was prepared in the same manner as in Example 1 except that the spraying distance was 190 mm. The bright portion of the thermal plasma containing nitrogen was not in contact with the substrate, and the temperature of the portion irradiated with the plasma during film formation was in the range of 400 ° C. to 700 ° C. as measured with a radiation thermometer. The substrate back surface temperature measured with the thermocouple 114 brought into contact with the substrate back surface was 150 ° C.

The obtained sprayed film had a thickness of about 200 μm. When the crystal structure was analyzed by X-ray diffraction, the peak intensities of Fe ₄ N and iron were observed. Analysis of the composition by fluorescent X-ray analysis revealed that iron nitride was 11 mol% and iron was 89 mol%.

Example 4
An iron nitride sprayed film was produced by the apparatus shown in FIG. After roughening the surface by blasting using carbon steel as a base material 25, the base material was attached to the apparatus, and the spraying distance 24 was set to 30 mm. Next, plasma gas was introduced by introducing 40 L / min of nitrogen and 10 L / min of hydrogen and supplying power of 35 kW to generate thermal plasma.
The bright part of the thermal plasma 28 containing nitrogen and hydrogen generated under these conditions was in sufficient contact with the substrate.
Nitrogen gas was sprayed on the back surface of the base material to cool the base material. Thus, since the base material is cooled from the back surface, no preheating is performed.

Next, iron powder (average particle size of 40 μm) was supplied at about 3 g / min by a fine powder supplier manufactured by Technoserve, and was put into a thermal plasma containing nitrogen and hydrogen. The 100 mm square substrate 25 was moved left and right at a speed of 150 mm / second, and spraying was repeated while repeatedly moving up and down at a speed of 4 mm / second to deposit 10 thermal spray layers uniformly. The temperature of the portion irradiated with plasma during film formation was in the range of 1500 ° C. to 1700 ° C. as measured with a radiation thermometer. The substrate back surface temperature measured with a thermocouple 29 brought into contact with the substrate back surface was 200 ° C.

The obtained sprayed film had a thickness of about 200 μm. When the crystal structure was analyzed by X-ray diffraction, the peak intensities of Fe ₄ N and iron were observed. Analysis of the composition by fluorescent X-ray analysis revealed that iron nitride was 33 mol% and iron was 67 mol%. As a result of SEM observation of the cross section of the sprayed film, the film was dense.

Example 5
The hardness of the sprayed films of Examples 1 to 4 and Comparative Examples 1 and 2 was measured using a Vickers hardness meter at a load of 100 g. The hardnesses were 250 Hv, 150 Hv, 370 Hv, and 110 Hv from Example 1 to Example 4, respectively, 75 Hv in Comparative Example 1, and 80 Hv in Comparative Example 2. In the examples of the present invention having a high iron nitride content, high hardness was obtained, and in particular, the higher the iron nitride content ratio, the higher the hardness.

Example 6
The samples on which the thermal spray coatings of Examples 1 to 4 and Comparative Examples 1 and 2 were formed were immersed in aqua regia at a temperature of 60 degrees. When visually confirmed after 10 hours, the carbon steel as the base material was dissolved in all examples. On the other hand, the sprayed film remained unchanged from Examples 1 to 4, but in Comparative Examples 1 and 2, the portion considered to be residual iron was selectively dissolved and the surface was roughened. It was confirmed that the thermal spray film of the present invention was excellent in oxidation resistance.

The iron nitride sprayed coating of the present invention having such characteristics and the method for producing the same can be used as a coating suitable for coating structural materials and parts that require characteristics such as corrosion resistance and wear resistance.

It is a figure which shows an example of the apparatus for manufacturing the sprayed film in this invention by pressure reduction. It is a figure which shows an example of the apparatus for manufacturing the sprayed film in this invention by a normal pressure.

Explanation of symbols

101: Substrate 102: Substrate holder 103: Vacuum chamber 104: Thermal plasma 105: Spacer 106: Thermal spray distance 107: Rotary pump 108: Sheath gas 109: Plasma gas 110: High-frequency coil 111: Powder feeder 112: Carrier gas 113: Quartz tube 114 of thermal plasma source: Thermocouple 20: Cathode 21: Anode 22: Plasma gas line 23: Powder supply line 24: Spraying distance 25: Substrate 26: Sprayed film 27: DC power supply 28: Thermal plasma 29: Thermocouple

Claims (6)

An iron nitride sprayed film formed by a thermal spraying method, having a film thickness of 1 μm or more and 3 mm or less, iron nitride in the film of 25 mol% or more and 100 mol% or less, and the balance being made of only iron. The member which coat | covered the iron nitride sprayed film of Claim 1 to the base material. In an apparatus having a part for generating a thermal plasma and a part for holding the base material, iron is introduced into the thermal plasma while bringing the bright part of the thermal plasma containing nitrogen into contact with the base material. A method of forming a sprayed coating mainly composed of iron nitride, wherein the temperature of the coating formation site is controlled to be equal to or lower than the decomposition temperature of iron nitride by controlling the temperature of the substrate. Method. 4. The manufacturing method according to claim 3, wherein an apparatus having a part for generating thermal plasma by high-frequency or direct-current arc in a decompression vessel and a part for holding the substrate is used. The thermal spraying film obtained by the method of claim 3 or claim 4 is irradiated with thermal plasma without introducing iron while contacting the bright part of the thermal plasma containing nitrogen, and the temperature of the coating formation site is nitrided The method for producing an iron nitride sprayed film according to claim 3 or 4, wherein the nitriding of iron is advanced by keeping the iron decomposition temperature or lower to nitride the iron in the sprayed film. The method of manufacturing an iron nitride sprayed film according to any one of claims 3 to 5, wherein the thermal plasma contains nitrogen and hydrogen.

Images