JPS59107990A - Carbide coating method for carbon-containing materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a fluidized bed furnace to process the surface of materials containing carbon, titanium (Ti), and vanadium (V).

Related to a surface treatment method for forming a carbide layer of niobium (Nb), tank/I/(Ta)r chromium (Cr), or manganese (Mn) (hereinafter, these elements are collectively referred to as carbide-forming elements) It is something.

Conventionally, it was used as a furnace for heat treatment of steel to produce alumina powder.

Fluidized bed furnaces have been used that use a fluidized bed made into a fluidized state by blowing gas such as air or argon as a heat medium. Since this heat medium has a uniform temperature distribution and rapid heat transfer, it is possible to rapidly heat an item and uniformly heat each part of the item using this heat medium.

Therefore, attempts have already been made public to perform diffusion coating on metal surfaces using F's fluidized bed furnace.

This method will be explained based on FIG. First, a treatment agent made of a mixed powder of a substance containing a penetrating element and a chloride is placed on a diffuser plate in the furnace body a of a fluidized bed furnace.

Then, the inert gas is passed through the gas supply passage C1 to the furnace body a.
Inject the processing agent powder into a fluid state.

A fluidized bed d is formed. Then, the lid e on the top of the furnace body a is removed, and the material to be treated f is buried in the fluidized bed d.

Tighten lid 0. In that case, be careful to ensure that the furnace is sealed tightly. Next, using hydrogen as a carrier gas, the halogen vapor of the activator passes through the gas supply passage C1 and enters the fluidized bed d.
supplied to Then, the halogen vapor and the powder of the penetrating element react with each other, and a gas of the halide of the penetrating element is generated.

When the halide gas comes into contact with the material f to be treated in the fluidized bed d, it decomposes to cause penetrating elements to be deposited on the surface of the material to be treated. Diffusion coating is performed in this way.

However, this method has a problem in that the handling of the furnace and processing operations are extremely troublesome, as described below. That is, first, in order to form the coating layer by the eight-layer method, halogen vapor is required as an activator, and it is essential to use hydrogen as a carrier gas to transport the halogen vapor. However, hydrogen has a high risk of explosion.

Therefore, great care must be taken in sealing the piping and furnace. Therefore, the operation of the furnace is not necessarily efficient. Second, since the furnace is used in a closed state to prevent hydrogen explosion, the material to be treated cannot be taken out of the furnace at high temperatures, so the base material must be quenched subsequently. is difficult. Eighth.

Since a halogen vapor generator is required, the structure of the furnace is complicated and the operation is complicated.

The present invention attempts to solve the above problem.

In other words, the present invention provides a surface treatment method that can safely form a carbide layer of a practical thickness in a short time using a fluidized bed furnace without using hydrogen or halogen vapor. The purpose is to

And 9 the claimed invention is a weight remina of 50 to 70% heavy weight,
A treatment agent consisting of three powders of 50 to 30% by weight of metals of carbide-forming elements or their alloys and 05 to 3% by weight of halogenated ammonium salts is placed in a fluidized bed furnace, and then After fluidizing the treatment agent by introducing a fluidizing gas to form a fluidized bed in the fluidized bed furnace, a material containing carbon is buried in the fluidized bed and heated. This is a method of coating a carbon-containing material with a carbide, the method comprising forming a carbide layer on the surface of the carbon-containing material.

In the method of the present invention, halogenated ammonium salt powder is used as a processing agent, and halogen vapor is not used. Therefore, there is no need for hydrogen as a carrier gas to carry the halogen vapor into the furnace.

Therefore, in the present invention, carbide coating treatment can be performed safely without the risk of explosion due to hydrogen.

Furthermore, since there is no need to seal the furnace, the material to be treated can be directly charged into the high-temperature fluidized bed. As a result, one item can be heated rapidly. Further, the base material can be easily quenched by taking the product out of the furnace in a high temperature state. Furthermore, since halogen vapor is not used, a halogen vapor generator is not required.

Therefore, in the present invention, a fluidized bed furnace that is simple in structure and operation can be used. Furthermore, since the processing agent powder in a fluid state is used as the heating medium, the processing agent does not adhere to the surface of the item. Therefore.

According to this method, an extremely smooth material surface can be obtained. Furthermore, since the temperature distribution of the fluidized bed is uniform, a carbide layer of uniform thickness can be formed on the surface of one product. In addition, a fluidized bed furnace in which two types of carbide-forming element metals are simultaneously mixed and used as a treatment agent component in the side wood invention,
Generally dry.

A fluidized bed furnace commonly used for incineration, reduction, etc. may be used.

Advantageously, the alumina is present in the treatment agent in a range of 50 to 70% by weight (2% by weight expressed as %). If the amount of alumina blended is less than 50%, the proportion of metal powder in the processing agent increases, and the weight of the entire processing agent increases, making it difficult to fluidize the processing agent, which is not preferable.

Also, if the amount of alumina is more than 70%, a carbide layer will be formed, which is also not preferable.

Metals that are carbide-forming elements refer to metals that easily combine with carbon to form carbides, such as titanium, a group IV element, and Va
Group x element vanadium, -of, tanta lv, and th.
Representative examples include chromium, which is a group A element, and manganese, which is a group IV element. As alloys of carbide-forming elements, in particular,
Metals or alloys of carbide-forming elements such as Fe-V, Fe-Nb, and Fe-Cr can also be mixed and blended as a component of the treatment agent.

Ammonium halide salt, ammonium chloride (
NHaCll), ammonium bromide (NH4B r
).

It consists of ammonium iodide (NH4r), ammonium fluoride (NH4F), etc. Ammonium halide salts react with carbide-forming elemental metals or alloys.

A halide gas of a carbide-forming element involved in carbide formation is generated. Therefore, if the amount of ammonium halide salt is less than 0.5%, the reaction of carbide formation is weak;
The thickness of the carbide layer formed is thin. However, when it exceeds 8%, the amount of halide gas generated increases,
U% is preferable because troubles such as exhaust hole clogging are more likely to occur.

The powder particle size of the processing agent ranges from 60 to 850.
Those in the mesh range are preferred. If it is coarser than 60 mesh, a large amount of fluidizing gas is required to fluidize the processing agent. As a result, the halide gas generated is blown away by a large amount of fluidizing gas and cannot reach the surface of the item (this is not preferable because the formation of 5-dimensional compounds does not proceed. This is also undesirable since the powder tends to float and becomes difficult to handle.

As the fluidizing gas, an inert gas is used so that no reaction occurs when it comes into contact with the processing agent. Among these, argon of ordinary purity is commonly used.

The fluidizing gas is injected into the fluidized bed furnace at a predetermined pressure and flow rate. As a result, the processing agent powder is blown up into the furnace, and does not fall down due to the pressure of the fluidizing gas that subsequently flows in, forming a fluidized bed that moves in the furnace in a suspended state. but,
The pressure and flow rate of the fluidizing gas required to fluidize the processing agent vary depending on the particle size of the processing agent powder. For example, if the particle size of the processing agent powder is about 80 mesh, the pressure of the fluidizing gas will be .

Preferably, the flow rate is 15 to 2 kg/d and the flow rate is 4 to 6 l/min.

As the material to be treated in the present invention, a material containing 1 carbon can be used. In addition, examples of materials containing carbon include carbon-containing metal materials 1 such as iron, nickel, and cobalt, and carbon materials mainly composed of graphite. The carbon contained in the treated material and the carbide-forming element in the treatment agent combine to form a carbide of the carbide-forming element on the surface of the treated material. It is necessary to contain carbon.

If the carbon content is less than 0.1%, it may be difficult to form a carbide layer, or it may take a long time to form a carbide layer to a practical thickness.

The heating step of the present invention is performed by heating a fluidized bed that is a heat medium. Specific heating methods include placing a sulfur bed furnace containing a fluidized bed into an external heater such as an electric furnace and heating the fluidized bed from the outside, or heating the fluidized bed from the outside. By heater.

Any method that directly heats the fluidized bed may be used. The heated fluidized bed contacts one item and heats the item.

As a result, a carbide layer was formed on the surface of the nine products.

The heat treatment temperature is selected within the range of 700°C to 1200°C. If the temperature is lower than 700° C., a carbide layer of sufficient thickness will not be formed on the surface of the treated material. On the other hand.

If the temperature exceeds 1200° C., the treatment agent tends to stick and solidify, and there is also a risk of deterioration of the material of the material to be treated, which is not preferable.

The treatment time is selected between 0.5 and 16 hours, taking into consideration the required thickness of the carbide layer and the material of the material to be treated. If the heating time is shorter than 0.5 hours, a carbide layer of sufficient thickness may not be obtained. Also, if heated for more than 16 hours.

Material deterioration of the treated material is likely to occur.Generally, in order to obtain a carbide layer of a constant thickness, a relatively short treatment time is required at a high treatment temperature, and a relatively long treatment time is required at a low treatment temperature.

Hereinafter, nine aspects of the present invention will be described in detail.

Example 1 The carbide coating treatment of the present invention was carried out using the fluidized bed furnace shown in FIG. In the fluidized bed furnace, a gas supply passage 2 is opened in the lower part of the furnace body 1, and a diffuser plate 8 is provided 4 directly above the opening to partition the inside of the furnace into two parts. The diffuser plate 3 has a large number of gas dispersion holes extending through the thickness direction 10. The top of the furnace body 1 is covered with a removable lid 4,
A gas exhaust passage 5 is opened in a part of the lid 4. A heater 6 is installed on the outer periphery of the furnace body 1. Also,
The furnace body 1 is made of heat-resistant steel and has a shape of 60n in diameter x
It has a columnar shape with a height of s o fpl.

Processing agent powders 1 to 1 were placed on the diffuser plate 8 of the fluidized bed furnace. What is the blending ratio of each component in the processing agent?

100-200 mesh) and L5% ammonium chloride powder (80 mesh). Then, argon gas was added as a fluidizing gas at a pressure of 15'j/d and a flow rate of 6.
l/lr+in "C', the processing agent powder was fluidized from the waste supply passage 2, and a fluidized bed 7 was formed.

Next, the lid 4 on the top of the furnace body 1 was removed, and a material to be treated (Next Tool Steel JISSK 4, height '200n x diameter 7 edition) 8 was suspended in the fluidized bed 7 via a support. Next, the flow N7 was heated to 950° C. from the outside of the furnace body 1 by the heater 6. After heat treatment was performed at that temperature for 2 hours, it was allowed to cool as it was.

When the surface of the thus obtained treated material was visually observed, it was found that there was no adhesion of the treatment agent and the material surface was smooth. When the cross section was observed under a microscope, it was found that a coating layer of 4 to 6 μm was uniformly formed, as shown in the micrograph of FIG. When this layer was analyzed by X-ray diffraction, it was confirmed that it was a subvanadium oxide (VC) layer. Further, when the hardness of this layer was measured, it showed a hardness of approximately Hv3.500.

Example 2 The blending ratio of each component of the treatment agent was 45% Tulo titanium powder (45% titanium content, 100 to 150 mesh)%7.
5% ammonium chloride powder (80 METSU V-) Oyohi R part alumina powder (80 METSU V-) and base treatment agent 1
I prepared kg. This treatment agent was used on the same treated material as in Example 1.

Carbide coating was performed under the same conditions. Obtained JISSK
Figure 4 shows a cross-sectional micrograph of the surface of the 4 materials. 4-5μm
A smooth coating layer was formed. When this layer was subjected to X-ray diffraction, it was confirmed that it was a titanium carbide (TiC) layer. In addition, when we measured the hardness of this layer, it was found that it was approximately Hv
! It showed a hardness of 3000.

In addition, using the same treatment agent as above, cemented carbide (WC-
A carbide coating treatment was performed under the same conditions as in Example 1 using 6%Co2) as the treated material. the result.

A titanium subride layer with a thickness of 1 to 2 μm was formed on the surface of the cemented carbide.

Example 8 The blending ratio of each component of the treatment agent was changed to 40% chromium powder (1
00-150 mesh), 1% ammonium bromide powder (80 mesh), balance alumina powder (80 mesh)
1 kg of processing agent was prepared. Using this processing agent,
Carbide coating treatment was carried out under the same conditions as in Example 1 except that JISSK4 material was used as the material to be treated. As a result, the surface of the treated material was 4 to 5 μm thick as shown in the W4 micrograph in Figure 6.
A smooth coating layer was formed. X-ray diffraction confirmed that this layer was a chromium carbide layer.

Further, a carbide coating treatment was performed under the same conditions as in Example 1 using the same treatment agent as above and using graphite as the λ↑ treatment agent. As a result, a 2-8 μm smooth ROM carbide was formed on the surface of the graphite.

In addition, it was measured that each chromium carbide layer had traces of approximately Hv15001.

Example 4 The blending ratio of each component of the treatment agent was 50% ferroniobium powder (containing 65% titanium and 3.4% tantalum, 1
00 to 150 mesh), 25% ammonium chloride powder (80 mesh: L), and the remainder alumina powder (1 kg) was prepared.

In addition, the pressure of the fluidizing gas was set to 2/d, and the flow rate was set to 41/mi.
The processing agent was fluidized as n. Using this processing agent,
Carbide coating was performed using JISSKDII as the material to be treated under the same conditions as in Example 1. As a result, JISSKDII
A smooth coating layer of +1 to 2 prn was formed on the surface of the material. Based on the results of analysis by X-ray diffraction and research, it was confirmed that the layer was a niobium carbide (NbC) layer. In addition, elemental analysis using an X-ray microanalyzer confirmed that tantalum was also present in the coating layer in addition to niobium and carbon.The hardness of this layer was approximately Hv2500. .

Example 5 The blending ratio of each component before wound treatment was 85% Ferromanff.
3% ammonium chloride powder (80 mesh),
and 1 kg of a processing agent with the remainder being alumina powder (80 meth) was prepared. Using this processing agent, JISSK4
wood as the material to be treated.

Carbide coating was performed under the same conditions as in Example 1. the result,
A smooth coating layer of 7 to 8 μm was formed on the surface of the JISSK4 material. From X-ray diffraction, it was confirmed that this layer was a submanganese compound layer.

The hardness of this layer was approximately Hv1400.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an outline of the prior art. 21: Furnace main body, 2: Gas supply passage, 8: Diffuser plate. 31 is the gas dispersion hole, 4 is the lid, and 52 is the nu discharge passage. 6: Heater, 7: Fluidized bed, 8: Material to be treated Applicant Toyota Central Research Institute Co., Ltd. Agent Figure 1 Figure 2 (-X4ω) (X400) (x4ω)

Claims (1)

Claims: 50 to 70% by weight of alumina, 50 to 30% by weight of carbide-forming element metals, or alloys thereof. and 0.5 to 8% by weight of a treatment agent consisting of three types of ammonium halide powder powders are placed in a fluidized bed furnace,
Next, a fluidizing gas is introduced to fluidize the processing agent to form a fluidized bed in the fluidized bed furnace, and then a material containing carbon is buried in the fluidized bed and heat treated. A method for coating a carbon-containing material with a carbide, comprising forming a carbide layer on the surface of the carbon-containing material.