JPS5827971A - Melt spraying for metal - Google Patents

Abstract

PURPOSE:To form a coating layer having high abrasion resistance and corrosion resistance on the surface of a substrate by heating a gas other than oxygen having reactivity with the metal to be melt sprayed to convert the same to plasma, introducing the metal into said plasma under controlling of the partial pressure of oxygen and melt spraying the metal by allowing the same to react with the plasma of said gas. CONSTITUTION:A gas other than oxygen for example, gaseous nitrogen, gaseous hydrocarbon or a gaseous mixture thereof having reactivity with metal to be melt sprayed, such as Ti, is heated, whereby the gas is converted to plasma. A plasma jet, plasma flame or arc discharge method is used for the formation of the plasma. Said plasma gas is ejected through a nozzle to form excited high speed jets of 1-3 Mach and about 1,000 deg.C. Metallic powder is charged into said plasma in the neighborhood of the nozzle by limiting the presence of oxygen to <=10<-4>Torr partial pressure of oxygen, to melt the powder by heating and to allow the same to collide against the surface of the substrate, whereby a coating layer is formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal thermal spraying method, and more particularly to a metal thermal spraying method for forming a hard coating on the surface of a material to be treated by plasma spraying of metal.

TrN as a T1 compound among metal compounds.

TIC and Ti (CN), etc., have excellent wear resistance and surface corrosion resistance, and are often used to form surface treatment coatings for parts that are subjected to aqueous treatment.
It was formed by VD method (chemical vapor deposition method) or the like. However, the thickness of the titanium compound coating layer obtained by these conventional methods is only about several μm, and the purpose of surface treatment cannot be sufficiently achieved. Furthermore, the equipment for carrying out these methods is complex, large-scale, expensive, and requires a significantly long processing time.

In other words, all of these conventional methods are a type of vapor deposition method in which a coating layer is formed on the surface of the processing member using evaporated particles of a halide such as TI or TiCl2 generated by heating. The strain within the layer increases, and the resulting residual stress reduces the adhesion of the coating layer, and in some cases, the coating layer peels off from the surface of the processing member and falls off. There is also a method of forming an intermediate layer between the processing member and the coating layer in order to improve the adhesion.
Even in this case, the thickness of the Ti compound layer as a coating layer is limited to several tens/Im or less. Even if the Ti compound itself has excellent surface 1 abrasion resistance and corrosion resistance, the purpose of the treatment cannot be fully achieved with a surface treatment layer of this thickness.

In addition, among the conventional methods mentioned above, the reactive vapor deposition method (A I (, E method) used as a typical method of the PVD method has an IQ"
Ti was evaporated in a processing chamber that was evacuated to approximately
In a processing chamber maintained at a temperature of ~10-2 Torr, a cathode glow is performed under the ball to cause Ti and a reactive gas to react, and a Ti compound is vapor-deposited on the surface of the material to be processed as a cathode. Therefore, in this method, it is necessary to evacuate the processing chamber to a high degree of vacuum, and a mechanism for rotating the material to be processed in the processing chamber is required in order to obtain a uniform vapor deposition coating, and also to ensure good adhesion with the coating layer. In order to do this, the surface of the material to be treated must be heated to a high temperature of 800-1000'C.

For this reason, in the PVD method, the equipment generally becomes large, complicated, and expensive. Formation of a small-scale treatment film is performed by vapor deposition of a few atoms or particles as small as clusters, so the rate of film formation is extremely slow.

On the other hand, in the Cvl) method, although the processing is not so multi-Kf, the formation rate of the coating layer is extremely slow at about 0.01 to 0.1 μm/mm, it takes an extremely long time to form a layer of several μm, and a large amount of Requires processing energy.

In addition to the vapor deposition method, a surface treatment layer has also been formed by plasma spraying using 'Pi as a spraying material, but in this case, TiN or TiC cannot be obtained. Furthermore, a method of thermally spraying TiN or the like itself is known, but in this case, due to the high melting point of TiN, sufficient melting is not carried out even in plasma, and the resulting surface treatment layer becomes porous. Wear resistance and corrosion resistance are significantly reduced.

The purpose of the present invention is to eliminate such drawbacks of the prior art and to achieve T1
Provides a metal spraying method that can form a hard surface treatment layer of a metal compound with excellent wear resistance and corrosion resistance on the surface of a workpiece through a relatively simple process using metals such as metals as a spray material. It's about doing.

The object of the present invention is to provide a metal thermal spraying method for forming a hard coating on the surface of a material to be treated by thermal spraying a metal, in which a gas other than oxygen that is reactive with the metal to be thermally sprayed is heated and turned into plasma; A metal is introduced into this plasma under the control of oxygen partial pressure and reacted with the plasma-formed gas.
This is achieved by a metal spraying method characterized by forming a coating of a metal compound as a reaction product on the surface of the material to be treated.

The method of the present invention will be explained in more detail below.

First, the gas that forms plasma is usually Ar.

■■e or N2 is used, and in some cases N2 is mixed in order to increase the amount of plasma heat generation.

Some of these gases are in an excited state in the plasma, but Ar, Ie, etc. are inert and do not cause any reaction with spray particles, such as T1, and l-1
2 exhibits only a reducing effect, whereas excited N2 is active and causes a significant reaction with Ti particles.

This has also been demonstrated by ionic nitridation using N2 excited in a glow discharge.

Therefore, the present inventors investigated the use of the highly reactive excited N2 or C gas as described above, and focused on Ti, which has a low free energy for forming nitrides or carbides, as a thermal spray metal. Compared to other elements such as Fe and Cu, the oxides and titanium oxides of Ti are very stable, and Ti is heated and melted in plasma and becomes thermally active.Ti is excited and becomes active. It is thought that it will react easily. However, since Fe, Cu, etc. have a large free energy for forming nitrides, their activity is small to the extent that they react with N2. In a state where 02 is extremely small, Ti particles and N
The reaction with 2 gases is mainly dominated by the diffusion of N2 into Ti. In the case of thermal spraying, the 11 particles are heated and melted in plasma and are in a liquid phase state. Therefore, T in the solid state
The diffusion rate is significantly slower than when processing soot into a gaseous or ionized state. Furthermore, in the case of thermal spraying, the Ti that reacts with N2 gas is in a state where there are many minute droplets of fine powder heated and melted17, and the surface area that participates in the reaction with N2 gas is significantly larger than in the case of bulk material. Become. For plasma formation, plasma jet,
Plasma flame, arc discharge method, etc. are used. For example, in the plasma jet method, a water-cooled WgA anode and a water-cooled Cu anode are used.
An arc discharge is formed between the cathode nozzle and a gas such as Ar, IIee N2*II2, etc. is flowed into the arc discharge region at high speed to excite the gas and turn it into plasma, which produces Cu.
Plasma gas is adiabatically expanded and ejected from a manufactured nozzle,
A high-velocity jet of excited Matsuha 1-3 is formed at a high temperature of about 10,000 C. Powder is introduced into the plasma, heated and melted, and collided with the surface of the material to be treated at high speed to form a coating layer.

Next, in order to form Ti tinides, there is a problem of the surrounding atmosphere gas (mainly air) being mixed into the plasma, and in particular, 02 causes an oxidation reaction of the sprayed particles. For example, in the thermal spraying method using a general plasma jet, the mixing of surrounding atmospheric gas into the plasma is related to the distance from the nozzle of the plasma ejected from the nozzle, and the general thermal spraying distance is 1.
It is reported that 50+nzn is about 20%. Therefore, in materials such as Ti, which have a small free energy for forming oxides, when 02 exceeds a certain level, the reaction with 02 takes precedence over the reaction with N2, and the formation of tinides becomes extremely small. . In the present invention, the amount of oxygen is limited to an oxygen partial pressure of 10'''4 Torr or less, and the Ti powder injected near the nozzle reacts effectively with the N2 excited in the plasma to generate Tl. It is like forming a chloride.

In the method of the present invention, the particle size distribution of particles such as Ti as a thermal spray material is also an important factor. That is, if the T1 particles are too large, the amount of N2 diffused into the TI will be reduced, and the desired characteristics of the treatment will not be sufficiently obtained. On the other hand, if the particles are too small, the oxidation reaction will proceed excessively and the amount of tinides will increase, reducing the toughness of the coating layer, and the melting temperature of the powder will rise due to the formation of tinides. The porosity in the coating layer increases, reducing corrosion resistance. Therefore, in the present invention, it is desirable to use Tl powder having an appropriate particle size distribution so that a certain amount of unreacted TI or Ti that is not a stable tinide is present.

The particle size distribution is preferably 1100zz or less and 1 μm or more.

The metal used as the thermal spray material in the method of the present invention is preferably TI, and other metals such as W are also used;
For example, since Cu, Fe, etc. have a large free energy for forming a tinide, it is difficult to form an effective tinide layer in which the above-mentioned tinide formation process takes place. Although the formation of Ti tinide was explained above, in the case of Ti carbide, N
Similar results can be obtained by using a gas such as CI-I instead of the 2 gas.

Further advantages of using N gas as a plasma forming gas include the following. Ar is a typical plasma forming gas.

Examples include He, N2, etc., and among these, the velocity of the plasma jet is in the order of J-ie, A, r, N2, and the enthalpy of the gas, N, which controls the plasma temperature.
2. The order is Ar, I-Ie. When II2' is added to each gas, the enthalpy increases. By the way, it is more effective if the metallic titanium powder stays in the plasma for a longer time and the temperature of the plasma is higher. In contrast, plasma using N2 gas has a slow plasma jet speed and high enthalpy, so Ti powder stays in the plasma for a long time and receives a lot of heat from the plasma, so it cannot be heated to high temperatures and melted. This is effective in promoting the reaction between the Ti powder and the excited gas. In N2 gas plasma ■
Adding 12 dregs increases the enthalpy of the plasma, making it even more effective.

Next, the Ti powder introduced into the plasma is transported from a powder supply device using a carrier gas. Therefore, the carrier gas does not enter the plasma together with the Ti powder, and in the case of the present invention, the type of carrier gas is also important. N2
Using the gas as a carrier gas is effective in forming Ti nitride. In addition, since hydrocarbon gases such as Cl-I4 are flammable, their calorific value is large, and their use as plasma forming gases is not preferable from the viewpoint of wear and tear on the electrodes of the plasma generator. However, C as a carrier gas
Using I-, T, gas is an important method in some cases to obtain T1 carbides. In addition, when TI is sprayed using CH, etc. as a carrier gas in N2 gas plasma, T
A complex of carbide and tinide of i is obtained.

The properties and characteristics of the coating layer obtained on the surface of the material to be treated by the metal spraying method of the present invention will be explained below with reference to the drawings in comparison with those obtained by the conventional method.

FIG. 1 is a micrograph showing the metal structure of a cross section of a Ti compound coating layer formed by the method of the present invention, in which 1 is the material to be treated and 2 is the sprayed layer (11)i. Figure 2 shows the X, Ill! i1 diffraction results are shown. X
As is clear from the line diffraction results, Ti
The compound coating layer is composed of TiN and TI. on the other hand,
Figure 3 shows the results of X-ray diffraction of the structure of the coating layer when T1 alloy 'r'' IIi was thermally sprayed using the conventional thermal spraying method.

In FIG. 3, only Ti or TI oxidation and proboscis is observed. Table 1 shows the Pinkers hardness of the T1 compound coating layer produced by the method of the present invention and the TiN coating layer produced by the conventional thermal spraying method, PVD method, and CVD method.

Table 1 The hardness of the T1 compound layer formed by the method of the present invention is lower than that of the (12) TI compound formed by the PVD method or CVD method, which has a hardness of I-TV2000. The reason for such low hardness is considered to be that the coating layer of the present invention is composed of Ti and a Ti compound. Also, P
As a result of X-ray diffraction of the TiN coating layer by the VD method or CVD method, the TiN diffraction line had a sharp peak, but the width of the peak was wider as a result of the Ti compound layer by the method of the present invention. It is also inferred that the Ti compound is slightly deviated from the perfect stoichiometric Ti compound. However, in the T1 compound according to the present invention, even after treatment at 700C for 24 hours, no change in hardness or X-ray diffraction results was observed compared to before treatment, and no change occurred due to high temperature aging. Therefore, the Ti compound according to the present invention does not easily deteriorate in hardness not only due to aging at room temperature but also due to heat caused by friction when used as a wear-resistant member. The hardness of the Ti compound coating layer according to the present invention varies from about 800 to 1,400 depending on the thermal spraying conditions. For example, if CI-L gas is added to N2 gas and thermal sprayed, a portion of TiC is also formed and the hardness decreases. It can be made larger than when using only N2 gas.

The hardness of the Ti compound coating layer according to the present invention changes depending on the ratio of TI and TIN or TiC. Ti
, TiN or TIC, the relationship between the intensity ratio after X-ray diffraction and the hardness is shown in FIG. (If the ratio of TiN+TiC1/Ti is 0.1 or more, the hardness will be a value that satisfies wear resistance. On the other hand, if the ratio is 0.9 or less, the coating layer will have toughness and good wear resistance, resulting in a thick coating.) Defects such as cracks do not occur even when layers are formed.

As described above, the hardness of the Ti compound according to the present invention is slightly reduced compared to stoichiometrically perfect TiN, but this point is difficult from the viewpoint of forming a Ti compound coating layer.
This is one of the factors that makes it possible to form a coating layer as thick as 1.2 m. Also, its hardness HV is 800~
1400, which is sufficient as a hard coating layer, and when used as a wear-resistant member as described later, it exhibits superior properties compared to chemical T1 compound coating layers.

Next, the characteristics of the member whose surface is coated with the Ti compound according to the present invention will be explained. First, we examined the wear resistance properties. The test method was a large ball type abrasion test. The test conditions were as follows: The mating material was 5UJ-2 (11, C60 or higher), the wear distance was 200 m, and a turbine oil well 120 was used as the lubricating oil.
The loads were 12.6 mm and 18.9 mm. A member using S0M415 steel as a base material and having its surface coated with a Ti compound layer according to the present invention to a thickness of 150 μm, P
A member coated with a TIN compound layer with a thickness of 51 tm using the VD method and a member with a hardened layer formed with a thickness of 100 μm using ion nitriding were used as test pieces for comparison. The results are shown in FIG.

In Figure 5, 1 is the method of the present invention, 3 is the PVD method, 5 is the result of the ion nitriding method and the load is 12.6, 2 is the result of the method of the present invention, 4 is the result of the PVD method, and 6 is the result of the ion nitriding method. and the load is 1
It is 8.9Kg. When the load was small and the wear rate was low, there was no significant difference between the Ti compound coated member according to the present invention, the TiN coated member made by the PVD method, and the surface hardened member made by ion chilling (15). Differences occurred in large areas, and the Ti compound-coated member according to the present invention had superior properties compared to other 'treated members. On the other hand, when the load was large, the Ti compound-coated member according to the present invention had particularly excellent properties compared to other treated members. As described above, the Ti compound-coated member according to the present invention had excellent wear resistance when the wear rate was high or under a high load compared to other treated members.

The reasons for this are that the hard coating layer obtained by the method of the present invention is thick and the base material does not wear out due to wear of the coating layer due to wear, and that the Ti compound coating layer is thicker than stoichiometric TiN. One example of this is that it has a high degree of toughness.

Next, the corrosion resistance of the Ti compound coated member of the present invention was examined. The test method was a salt spray test using test pieces that had been subjected to the same surface treatment as in the abrasion test described above. As a result, the members coated with the Ti compound obtained by the method of the present invention had almost the same (16) corrosion resistance as the TiN-coated members obtained by the PVD method, and were superior to the nitrided members. Furthermore, when using the test piece after the wear test, T
There was no change in the corrosion resistance of the i-compound-coated member, but the corrosion resistance of the TiN-coated member due to the PVD method was significantly reduced in the portion where the coating layer had been consumed due to wear.

Therefore, the Ti compound-coated member of the present invention has excellent corrosion resistance, and is particularly effective in improving the corrosion resistance of wear members.

The method of the present invention further has the following advantages.

First, with the PVD method and CVD method, it was difficult to form a thick coating layer of several tens of micrometers due to the problem of peeling of the coating layer from the base material, whereas the method of the present invention Several hundred μm1 preferably ioo without peeling
A Ti compound coating layer with a thickness of ~200 μm can be formed. Also, the formation speed is determined by CVD method or PV method.
The speed is 10' to 10' times faster than conventional methods such as the method. Furthermore, in contrast to conventional methods, where the size of the material to be processed is restricted due to limitations such as the size of the processing chamber, in the method of the present invention, there is no particular restriction on the size of the material to be processed; It is possible to perform a local coating treatment on only the areas where a coating layer is required, which was difficult with conventional methods.

Example 1 Material to be treated (material: SCM4) using a steel grid.
15) was roughened, and then thermal sprayed using a plasma torch. The plasma torch uses a device with an output of 80 KW, uses commercially pure N2 gas as the plasma forming gas, has a N2 gas flow of t 45 t/min, and a plasma output of 4. A plasma jet was formed using OKW. There are no particular restrictions on the purity of N2 gas, but one with a low moisture content is desirable.

There are no particular restrictions on the N2 gas flow rate or the plasma output method.

Oxygen partial pressure in the atmosphere surrounding the plasma jet is 10""
'l'orr or less. Oxygen partial pressure was measured using an O2 sensor. As a method for controlling the oxygen partial pressure, a known method of sealing the periphery of the plasma jet with N2 gas was used. It is also possible to use an inert gas such as Ar or He. The roughened surface of the material to be treated was first preheated to 100 to 150 C using a plasma jet to remove impurities attached to the surface of the material to be treated. Next, Ti powder was introduced into the plasma jet from a powder supply device using N2 gas as a powder supply gas. There is no particular restriction on the amount of Ti powder supplied into the plasma. Furthermore, it is desirable that the Ti powder be introduced at a location close to the plasma jet outlet of the plasma torch. The Ti powder may be of commercially available purity (99.9%), and the powder with a particle size of 5 to 44 μm was used. There is no particular restriction on the particle size distribution of the powder, as long as it is within the range of 1 to 100 μm. The distance between the material to be treated and the nozzle opening of the plasma torch during thermal spraying (spraying distance) is 70 to 140
Approximately mm is desirable. Although the relative speed (traverse speed) between the material to be treated and the plasma torch was l m /8 (a), there is no particular limit to the traverse speed.

Further, the temperature of the surface of the material to be treated during thermal spraying is not particularly limited, but a higher temperature is desirable in order to obtain a dense Ti compound coating layer. As described above, Ti powder was plasma sprayed under the above conditions to form a coating layer (19) with a thickness of 150 μm on the surface of the material to be treated. The thickness of the coating layer is 1 m
m~5 II m1 preferably 5 Q Q 7zm-]
-Q Any thickness within the range of 1 tm can be formed. The result of X-ray diffraction of the obtained coating layer is as shown in FIG. 2, and the diffraction lines are those of Ti and TiN, and no TI oxide was observed. Further, as shown in FIG. 1, the microstructure of the cross section was observed to be a dense sprayed coating layer. As shown in Table 1, its hardness was 900 on Vickers hardness. The wear test results of the Ti compound coated member of the present invention described in 2 are shown in Figure 5, and the wear resistance is superior to that of the TiN coated member made by PvD or CVD, or the hardened member made by ion nitriding. The Ti compound-coated portion of the present invention was also superior in corrosion resistance to other treated materials in the J salt spray test.

Example 2 Ti powder was plasma sprayed using CTl4 as the Ti powder supply gas. Other conditions are the same as in Example 1. As a result of X-ray diffraction, the obtained Ti compound coating layer shows TI and T
In addition to IN, rIc diffraction lines (20) were observed. The cross-sectional structure of the coating layer was a dense thermal sprayed coating layer similar to that of Example 1, and the Vickers hardness was I-TV1350 as shown in Table 1.

The wear resistance and corrosion resistance were also excellent as in Example 1.

Example 3 In order to control the oxygen partial pressure in the atmosphere around the plasma jet, a device equipped with a plasma torch installed in a sealed processing chamber and a vacuum pump capable of evacuating the processing chamber was used. there was. In this example, 10 processing chambers were prepared in advance.
``The chamber is evacuated to a pressure of about 2 Torr, and then N and gas are introduced to reach a predetermined atmospheric pressure, a plasma jet is generated to maintain the pressure inside the processing chamber at a predetermined value, and thermal spraying is performed without evacuation. In this example, the atmospheric pressure was maintained at 150 Torr, but there is no particular restriction on the pressure value.In this case, N2 gas with a small oxygen partial pressure was introduced after exhausting the oxygen in the processing chamber in advance. The oxygen partial pressure inside the processing chamber is low.

The measured value of oxygen partial pressure in the processing chamber was measured using a solid electrolyte.
It was measured with a sensor and was 10"" Torr or less.

Other thermal spraying conditions are the same as in Example 1. In this example, the temperature of the material to be treated during thermal spraying was maintained at a high temperature. In this embodiment, the heat of the plasma jet is used as a heating means for the material to be processed, but it is also possible to use other heat sources as the heating means. The heating temperature is also not particularly limited, but in this example it is set to 700C. The following effects were obtained by forming a Ti compound coating layer by the method of the present invention by heating the material to be treated during thermal spraying or by using a plasma jet in a reduced pressure space. When Ti particles collide with the surface of the material to be treated, if the temperature of the material to be treated is low, the sprayed particles will be rapidly cooled by the heat absorbed by the material to be treated, but if the temperature of the material to be treated is high, the sprayed particles will The temperature gradient with the treated material is reduced so that the sprayed particles are no longer quenched. Therefore, the longer the sprayed particles are kept at high temperature on the surface of the material to be treated, the more likely it is that in addition to the reaction between the Ti particles and N2 in the plasma jet, the Ti The reaction with N2 and the diffusion of N into Ti proceed. Furthermore, since the peripheral resistance of the plasma jet becomes smaller in the reduced pressure space, the length of the plasma jet becomes longer and the sprayed Ti particles stay in the high temperature region of the plasma jet for a long time. As a result, Ti
The reaction between particles and N2 is promoted. Furthermore, since the solidification rate of the particles sprayed onto the surface of the material to be treated is slow, a Ti compound coating layer can be obtained with few internal defects such as coagulation and passage holes in the thermal spray coating layer that occur due to rapid cooling.

The Ti compound coating layer obtained in this example had a Vickers hardness of 1-IV1250 and was a dense Ti compound coating layer.

Further, its surface 4 abrasion resistance and corrosion resistance were equivalent to or better than those of Example 1.

Example 4 N2 or Are using 1, 6 tanφ Ti wire
Arc spraying was performed in a He atmosphere. For arc spraying, a device capable of emitting DC 4.0 I (W) was used, and two Ti
An arc was generated between the lines. In that case the current is 150A
, the voltage is 28V. Atmosphere (23): Thermal spraying was carried out in the air using compressed gas N2 at a rate of about 5 g/cm2 as a spraying gas at a spraying distance of 130 m2, so that the surface of the material to be treated (material SCM21) was coated with 0.0 gm. 3~0,5w
A thermal spray coating layer with a thickness of n was formed. -Buba for comparison,
Conventional atmospheric spraying was also performed. In this case, spraying was carried out in the atmosphere using compressed air as the spraying gas. According to the X-ray diffraction results, the coating layer in the conventional method was composed of Ti and Ti oxide, whereas the coating layer formed by the present example had diffraction lines of T1 and TiN. The hardness was OV 1000 on the Vickers hardness. Details of the T1 compound coating layer of this example [@Abrasive O]:
The corrosion resistance and corrosion resistance were equivalent to or better than that of Example 1.

Example 5 After generating a plasma arc with a semi-transfer type plasma torch, the distance between the nozzle [ ] of the torch and the material to be treated is reduced, and a plasma space is formed by the L, L--chies and the material to be treated. Then, Ti powder was introduced into the space and thermal spraying was performed. The main component of the plasma forming blade (24) was N2 gas. A shielding gas was flowed around the plasma nozzle to reduce the oxygen partial pressure in the peripheral area involved in plasma spraying to 10'''l'orr or less.

/- The main component of the gas was N2 gas.

The Ti powder used had a particle size distribution of 5 to 44 μm, but 1
There is no particular restriction as long as it is within the range of μm to 100 μm. The distance between the nozzle opening and the material to be treated is desirably about 10 to 20 cylinders. The material to be treated has an outer diameter of 150 mm and a length of 300 m.
A 1.2 WrIn coating layer was formed on the outer and inner circumferential surfaces of a tubular sample having a thickness of +n and a thickness of 5 cm. The coating layer has a Vickers hardness of r-rvsoo,
As in Example 1, the coating layer had excellent corrosion resistance.

Example 6 Using an explosive thermal spraying device and using a Ti wire of 0.2 amφ as a thermal spraying material, the atmosphere in the plasma space during thermal spraying was set to an oxygen partial pressure of 10''.
``Thermal spraying was performed in an N2 gas atmosphere of less than Torr.

The obtained thermal spray coating layer was mainly composed of a Ti compound, and its Vickers hardness was HVloooo. Moreover, the corrosion resistance of the coating layer had almost the same characteristics as in Example 1 (25).

[Brief explanation of drawings]

Figure 1 is a micrograph showing the cross-sectional metal structure of the Ti compound coated layer produced by the method of the present invention, Figure 2 is a diagram showing the X-ray diffraction results of the Ti compound coated layer according to the present invention, and Figure 3 is the conventional FIG. 4 is a diagram showing the relationship between the hardness of the Ti compound coating layer and the ratio of (T i N-1-TlC)/Ti according to the method of the present invention, FIG. 5 is a diagram showing the relationship between wear rate and wear loss. 1... Material to be treated, 2... Thermal spray layer. Agent Patent Attorney Shiki Takahashi (26) First Atsushi 20 Condolences 30 =i”, 40 0 0-5 LO
(Ti1 Shi TiC) / Lower 1 ¥ 5 Mouth friction Renfu (Y/sec)

Claims (1)

[Claims] 1. In a metal spraying method in which a hard coating is formed on the surface of a material to be treated by spraying a metal, a gas other than oxygen that is reactive with the metal to be sprayed is heated and turned into plasma. , characterized in that a metal is introduced into the plasma under control of the oxygen partial pressure and reacted with the plasma-formed gas to form a coating of a metal compound as a reaction product on the surface of the material to be treated. Metal spraying method. 2. The patented metal spraying method, characterized in that the metal introduced into the plasma is Ti. 36. The metal spraying method according to claim 1, wherein the gas reactive with the metal to be sprayed is nitrogen gas, hydrocarbon gas, or a mixture thereof.