JPS59123761A - Corrosion prevention method - Google Patents

Abstract

PURPOSE:To form a layer with superior resistance to corrosion due to a hot gas contg. HCl by successively forming the 1st layer of a mixture consisting of Cr and Ni in a specified ratio and the 2nd layer different from the 1st layer in composition by spraying on a metallic surface. CONSTITUTION:The 1st layer of a mixture I consisting of Cr and Ni in 2/8- 8/2 weight ratio of Cr/Ni is formed by spraying on a metallic surface which is exposed to a hot gas contg. HCl. The 2nd layer consisting of 30-70wt% mixture I and 70-30wt% alkaline substance or ceramics is formed by spraying on the 1st layer. Said spraying is carried out by applying plasma spraying. The preferred ceramics is aluminum oxide, and the most suitable alkaline substance is sodium carbonate. To the mixture I may be added <=3% Nb, Ta or other element, and the 3rd layer of ceramics may be formed on the 2nd layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of metals exposed to high temperature gases such as combustion scum containing HCl.

In recent years, the amount of waste containing chloride from households and industrial facilities, such as garbage containing plastics such as vinyl chloride, has increased dramatically, and how to dispose of it has become a problem. Currently, there are two common disposal methods: landfilling and incineration, but the former is increasing in proportion due to the depletion of land for landfills due to pollution problems such as soil contamination. Along with this gradual increase in waste, the amount of plus deck contained in the waste has also increased, and the energy contained in the waste has also increased, making it an urgent issue to recover it within the right column. From this perspective,
In recent years, various research and development have been conducted on devices that effectively utilize the heat of high-temperature combustion gas generated when chloride-containing substances, such as the above-mentioned wastes, are combusted, and some of them have already been put into practical use.

In these devices, HCl and Cl are present in the high-temperature combustion residue.
2. In addition to the presence of edible scum such as SOx, unburned substances and ash consisting of alkali metal salts, heavy metal salts, and other solid substances produced as a result of combustion inevitably coexist.

When metals exposed to such high-temperature combustion residue have ash attached to their surfaces and HCl coexists in the atmosphere to which the metals are exposed, their corrosion (high-temperature corrosion) becomes extremely severe.
It is also known that the corrosion rate increases with increasing temperature. In other words, if the surface crystallinity of the metal exceeds 300C, high-temperature corrosion will occur, and if it exceeds 400C, corrosion will become extremely severe. There is nothing that can stop this high-temperature corrosion.

Conventionally, the following two methods have been used to protect the metal materials of combustion furnaces from this type of high-temperature corrosion. One is to neutralize the acidic corrosive scum generated during combustion with an alkaline substance such as a carbonate sorter, or to incinerate alkaline substances together with the waste when burning waste that generates HCl such as PVC. There is a method of using a so-called neutralizing agent that is supplied to the combustion atmosphere. However, all of these methods are effective mainly for treating corrosive residue in combustion gas, but they are effective against high-temperature corrosion that occurs when ash adheres to the metal surface and HCl coexists in the atmospheric residue. This method was insufficient as a corrosion prevention method. In other words, high-temperature corrosion occurs due to the geometric relationship between the furnace internal structure and the metal surface where high-temperature corrosion occurs, the flow state of the combustion gas, and the mixed contact state of the corrosive gas and the neutralizing agent. This is because there are parts of the metal surface where carbonate and the like do not reach a sufficient amount for corrosion protection.

Another method is to lower the temperature of the metal material in the combustion furnace. That is, since this high-temperature corrosion progresses more rapidly when the metal surface temperature exceeds 400°C, the metal surface temperature is kept below 400°C. Therefore, when the combustion heat of waste is recovered as steam in a boiler, waste heat boiler, etc., the temperature of the tube wall of the heat transfer chamber of the boiler must be maintained below 400C, and as a result, the generated steam is at the design value. 20 kg/cm2, 300°C or less, and under operating conditions of a practical device, it becomes about 16 to 20 kg/cm2, 200°C. In such medium-pressure steam, for example, when energy is converted into electricity, which is the most common method, the power generation efficiency is considerably lower than that of the latest heavy oil-fired thermal power generation, and the power generation cost is also high.

The present invention provides a method that prevents the above-mentioned high-temperature corrosion and, as one result, enables continuous cooling with high-pressure steam.

In accordance with the required heat resistance, chromium and nickel are applied to metal surfaces exposed to HCl scum, such as incinerator parts made of a wide variety of metal materials, from carbon steel to heat-resistant alloys. A first layer of mixture (I) containing nickel in a weight ratio of 2/8 to 8/2 is first coated by thermal spraying, and then a second layer having a composition different from the first layer is applied thereon by thermal spraying.

Combustion furnace members are usually made of various steel materials, iron-based alloys, nickel-chromium alloys, etc., as required, so the present invention uses the above-mentioned nickel-chromium mixture, which has a sufficiently strong affinity for these materials and has good heat resistance. A first layer is formed on the surface of the incinerator member by thermal spraying. The mixture (1) consists only of nickel and chromium, or contains up to 3% of other elements based on the total of both. The reason why the chromium/nickel ratio of the mixture (I) is set to 20/80 to 80/20 is because it has good durability against heating cycle of adhesion with the base material. 20/80 is often used in plasma spraying, but in order to further improve the corrosion resistance of the second layer etc. when mixture (I) is included, increase the amount of chromium, such as 50/50, within the above range. good.

In addition, other elements take advantage of the properties of a mixture of the two to provide even greater strength and strength.
It is added to improve acid resistance, oxidation resistance, etc., and typical examples include niobium, tantalum, molybdenum, tungsten, aluminum, and silicon.

Since the first layer of mixture (I) does not have sufficient corrosion resistance for a combustion furnace member exposed to HCl, in the present invention, a second layer with sufficient affinity for the first layer and good corrosion resistance is used as the first layer. Form on top of the layer.

One second layer contains 30 to 70% by weight of mixture (I) and at least one alkaline substance or ceramic 70%.
Formed from ~30%. The mixture (I) in the second layer is 3
If it is less than 0%, the affinity of the second layer to the first layer will be insufficient, and peeling between the first layer and the second layer will easily occur, and the second layer will not be stable.
It is often difficult to form layers. This tendency is especially true for alkaline substances. On the other hand, unless the content of alkaline biological material or ceramics is 30% or more, the corrosion resistance of the second layer is generally insufficient.

As mentioned above, the present invention started from coating the first layer with a second layer made of the ingredients of the first layer and a material with better corrosion resistance. Surprisingly, in cases where the heat resistance is good up to 600C, such as in municipal waste incinerators, ceramics such as alumina or 30% of this is used as a second layer different from the above. Problems such as peeling do not occur even when using a layer substantially made of ceramics containing a first layer component of less than
Weight ratio of substantial ceramics to alkaline material: 7:
It has been found that the same results can be obtained by using a mixture of 3 to 3:7 and preferably 7:3 to 5:5 as the second layer. However, considering the heat resistance of the whole or part at a higher temperature such as 800 to 1000 C, there is less risk of peeling if the second layer is made of a mixture of the first layer components and a corrosion-resistant material.

Furthermore, when ceramics are used as the top layer as a corrosion-resistant material, the first step is to satisfy corrosion resistance at higher temperatures.
Preferably, a third layer made of ceramic is formed on the second layer made of layer components and ceramic. In this case, if the ceramic content in the second layer is not 30% or more, the affinity between the second layer and the third layer will be insufficient, and there is a risk of peeling between the two layers due to thermal history.

Also, for good bonding between both layers, the ceramics used for the second and third layers may be substantially the same.

The thermal spraying used in the present invention can be carried out by various thermal spraying methods as required, but Replasma thermal spraying is a typical method and is particularly useful for forming a dense coating layer that is useful in terms of corrosion resistance. It is also possible to reduce the oxide film by mixing hydrogen into the inert dregs used in plasma spraying or the like.

The ceramics used in this invention include oxides of silicon, aluminum, magnesium, calcium, zirconium, etc., carbides of silicon, boron, titanium, etc., and nitrides of silicon, boron, aluminum, etc., and at least one of them may be used.
Aluminum oxide is very typical.

It is sufficient that each layer used in this invention is mixed at the time of melting to form a sufficiently uniform layer. Of course, it is possible to form a uniform mixture of alloys or the like before thermal spraying if desired. It is generally preferable because it is easy to obtain various layers.

In the present invention, a first layer and a second layer having an intermediate composition are interposed between the base material and the second layer, or between the first layer and the third layer if there is a third layer. Further, an intermediate layer may be interposed between the base material and each layer and a layer having an intermediate composition, and such a shift can generally be expected to improve durability against thermal cycles.

According to the method of this invention, for example, H
Even if Cl and ash approach the high temperature metal surface, the alkaline material in the layer containing a sufficient amount of alkaline material that already exists reacts with HCl and becomes neutral salt ash, causing the high temperature on the metal surface to rise. By preventing corrosion, or by removing a coating layer made of substantial ceramics already present on the metal surface or a mixture of ceramics and chromium, nickel, etc., corrosion due to oxidation at high temperatures, HCl at high temperatures, or H
It exhibits excellent corrosion resistance against severe high-temperature corrosion when Cl and ashes of alkali metal salts, heavy metal salts, etc. coexist, and when the coating layer is made of a mixture of substantial ceramics and alkaline substances. Since this layer has the effects of both forming neutral salt ash and exhibiting corrosion resistance, high-temperature corrosion that reaches the base metal surface does not occur.

Any alkaline substance that can sufficiently exhibit the above effects may be used, and at least one of them may be used.
Among them, carbonates of alkali metals and alkaline earth metals and alkali silicates are representative. Examples of carbonates of alkali metals and alkaline earth metals include carbonates of Na, K, Ca, or Mg. One type is used, and sodium carbonate is usually most suitable from the viewpoint of anticorrosive performance and cost, and the alkali silicate is typically sodium silicate, potassium or lidium. Ru.

Although the field of application of the present invention has been described above with reference to a combustion furnace as a representative example, the present invention is of course applicable to various members exposed to high-temperature scum containing HCl.

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

Example: A metal-containing steel consisting of 2.2% chromium, 1% molybdenum, 0.15% or less carbon (all by weight), and the balance iron (
A large number of plate-shaped test pieces measuring 30 mm in length, 50 mm in width, and 4 mm in thickness were cut out from a rolled plate of SCMV4), and each test material was coated with various methods and then subjected to a corrosion resistance test.

The test material was coated using a commercially available plasma spraying machine, using a mixture of 60% argon and 40% helium (both by volume) as the spray gas under conditions of a DC voltage of 40 volts and a discharge current of 800 amperes. 30mm of test material
It was coated over an area of 50 mm. A corrosion resistance test was conducted using this coated test material as a test piece. The corrosion resistance test was carried out using a tubular electric furnace, and ash collected from an actual garbage incinerator was placed uniformly on the surface of the test piece on which a coating layer had been formed, and the inside of the tube was heated with 30% water vapor, 10% CO2, and 1000 ppm HCl.
The test piece was placed in a tubular electric furnace in which a high-temperature atmospheric gas having a composition of 20 ppm of , SO2 (volume %), and the remainder air flowed, and the test piece surface temperature was maintained at 600C. Five sides of the specimen other than the surface with an area of 30 x 50 mm to be tested were protected from corrosion by fine alumina powder and fibrous insulation. The composition of the ash collected from the garbage incinerator and placed on the surface of the test piece is 7.1% aluminum, 3.8% sodium, and 2.8% potassium.
, Calcium 14.5%, Magnesium 1.5%, Iron 6
．． 1%, silicon 15.2%, chlorine 2.1%, total sulfur 1
．． 1%, water content 0.1% (both weight %), and the remainder is mainly oxygen bonded to the above elements.

The corrosion resistance test was carried out under the conditions described above for a maximum of 10 days, and for comparison, SCMV4 without any coating was also subjected to the test.

After conducting the corrosion resistance test, the test piece was completely purged of N2 scum in the tubular electric furnace, and then taken out from the electric furnace and allowed to cool for about 5 minutes, after which the ash on the surface of the test piece was removed using a brass sink, and an inhibitor of 0.5 % Hequinamethyleneteramine was immersed in an aqueous hydrochloric acid solution (8% by weight HCl) for 30 minutes to remove corrosion products before the test. After washing with water and drying, the weight was measured and a corrosion resistance test was conducted. The so-called weight loss was determined by comparing the weight of the test piece that had been previously measured. Figure 1 shows the results of this corrosion resistance test, where the horizontal axis is the number of test days and the vertical axis is the weight loss (m) of the test piece.
g/effective surface area 15 cm2).

Further, the line numbers in the figure are the test piece numbers and also indicate the differences in the content of the coating layer, and each number uses a coating layer having the structure described below.

Test piece 1: SCMV4 steel without coating layer Test piece 2: SC
The first layer chromium-nickel alloy (20%
Cr-80%Ni) Second layer A mixed layer of 50% Na2CO3 and 50% chromium-nickel alloy (20%Cr-80%Ni) was coated with a thickness of 150μ each by plasma spraying.

Test piece 3: The same first plate as test piece 2 was placed on top of the SCMV4 steel material.
The second layer was coated with a mixed layer of 50% alumina and 50% chromium-nickel containing metal (20%Cr-80%Ni) each having a thickness of 100μ by plasma spraying.

Test piece 4: On top of the SCMV4 steel material, the first and second layers were the same as those for test piece 3, and the third layer was coated with alumina to a thickness of 50 μm by plasma spraying.

Test piece 5: The same first plate as test piece 2 was placed on top of the SCMV4 steel material.
The second layer was coated with alumina by plasma spraying to a thickness of 50 microns.

Test piece 6: On top of SCMV4 steel, the first layer is chromium-Niracle alloy (50% Cr-50% Ni), the second layer is 30% alumina, chromium-nickel alloy (50% Cr-50% Ni) 70 % mixture was coated with a blaster coater to a thickness of 100 microns each.

Test piece 7: On SCMV4 steel, the first layer is chromium-nickel alloy (85% Cr-15% Ni), the second layer is 30% alumina, chromium-nickel alloy (50% Cr-50% Ni) 70 % mixture to a thickness of 100 μm each by plasma spraying.

Test piece 8: Chromium-silicon-nickel alloy (20%Cr-10%Si-70%Ni) in the first layer on SCMV4 steel, 30% alumina in the second layer, chromium-nickel alloy (50%Cr- A mixture of 50%Ni) and 70% was coated by plasma spraying to a thickness of 100μ each.

As shown by the line in Figure 1, in the case of a test piece without a coating for corrosion protection, the weight does not decrease and the amount of corrosion increases with the passage of time. The annual corrosion rate is 1.5 mm or more.

In contrast, in the test pieces 2, 3, 4, 5, and 6, in which the present invention was applied and a coating layer effective for corrosion prevention was formed, there was almost no weight loss, which was below the measurable limit value. In other words, there was almost no corrosion, proving the effectiveness of the present invention.

In addition, in test piece 7 shown by line 7, when the chromium content of the first layer increases beyond the range of the present invention, the coating layer peels off, and similarly as in test piece 8, the first layer contains chromium and nickel. If a third element other than silicon is added in an amount as large as 10%, the coating layer will peel off, resulting in no corrosion-preventing effect.

Furthermore, in test piece 2, Na2CO3 was replaced with Na2CO3.
In test piece 9 and test piece 5 obtained using SiO3, the weight ratio of alumina and Na2CO3 was 1:1 instead of alumina.
When a similar corrosion resistance test was conducted using test piece 10 obtained using the mixture of test piece 1, the same results as test piece 2 and test piece 5 were obtained.

Patent applicant: Toyo Engineering Link Co., Ltd. 1, Koi'
[Table of: 1981 Edition No. 229333''/
:23 Title of the invention Corrosion prevention 51 person 3, person making the amendment, tenancy, etc. Applicant 5, ``1IIIiI subject matter `` n Dai, text to Meihong a5 yohi four sides 6, contents of the amendment γ + + Moon, 1) (''ξl));Snoring;, 13 Yohi Part 1
Figure 5]・]〈÷

Complete text correction by Akira Waru Ex. 1, title of invention 7 people in corrosion protection 2, ff-! 1Δ′ [Claim 1) I A corrosion prevention method characterized by forming the first layer of I) and a second layer having a composition different from the first layer thereon by thermal spraying.

2) 2nd grade or the mixture by weight ratio 3 (')% ~
70% and at least one kind of alkaline goods 70% to 30%
1. The method according to item 1, wherein

3) The second layer has a weight ratio of C additive (! > 30 to 70% and ceramics 70 to 30%) Claim 11
A lot of things written by Sada.

4) The second layer is essentially made of ceramics! 1. The method according to claim 1.

5) Second layer or substantial ceramics by weight ratio 70-3
2. The method according to claim 1, comprising 30 to 70% of the carbonaceous material.

6) 'i: A third layer made of ceramics on top of the two layers.
10,000,000,000,000,000,000,000,000,000,000,000 (10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 (300,000,000000000000 type) type type type form form each layer.

7)) Compounds (I) [Claims 1 to 5] containing 3% or more of other elements in addition to nickel
The nonj people of Teiki, ll'i,.

ε3) 't'RC1l or Zosysma spraying special 3'
1 Claims 1-6 ] i'j +) self 6.
My father's 1,000.

3. Invention of the invention, J (Meiko's invention 14) Contains C, l; Prevents corrosion of the blade, which is exposed to G-warm scum, such as burnt scum.
There are things related to people.

Nearby 1゛, house 1 [1! ＋、'、r Business facilities (・+?) Waste containing chloride, for example, garbage containing plastics such as salt L:', should be donated as much as possible, such as hanging or paper.
It's a matter of reason/person/). Current) e, -I"'Q-like processing as 7 people [, Riri-C method and Yazuki 1 Buddha or precancerous cancer (There are also pollution problems such as soil destruction and depletion of land for landfill. (The ratio of the koguri-juice method has increased.The amount of waste has increased. 5] -
Nerky is also becoming more expensive, and its effective recovery has become an urgent issue. From this point of view, substances containing chlorides, such as the above-mentioned wastes, are avoided and generated, resulting in a reduction in drought H1.
Various devices have been researched and developed in recent years to effectively utilize the calorific value of burning gas, and some have already been put into practical use. In these devices, l-I C, C and 2. In addition to the presence of corrosive gases such as SOX, unburned substances and alkali metal salts and heavy metals generated as a result of combustion! , 'Ashes consisting of IA and other solid substances inevitably coexist. Metals that are exposed to such high-temperature combustion residue have ash attached to their surfaces and HCi in the atmosphere to which the metals are exposed.
It is known that when they coexist, the corrosion rate of ItX (high) corrosion becomes more intense, and the rate of corrosion increases with the rise of wet grass. That is, the surface temperature of the metal is 3
When the temperature exceeds 00°C, high-temperature corrosion occurs, and when the temperature exceeds 400°C, the corrosion is particularly severe/Among commercially available practical metal materials, only a few special high-grade metal materials can withstand this high-temperature corrosion. Uruchino is not there.

Conventionally, the following two methods have been used to protect the metal A3I of combustion furnaces from this type of high-temperature corrosion. One is to neutralize the acidic corrosion generated during combustion by reacting with an alkaline substance such as carbonate sorter.
Alternatively, 54 people use so-called neutralizer 1 in the combustion atmosphere, which supplies C alkaline substances to the furnace together with waste historical materials when burning waste that generates C-2. There is. C
For treating snacking and eye scum in combustion scum (, 1, 6 effective, gold,: ash or 6 and atmosphere condensed; scum inside) /] 1 The coexistence of the B4 with the help of J Le'f4 (
K: '1ii? MfiL'AUL-(0)
', 'J2 = b 'L t'v 'C:J, 4□
That's enough.3. Juku;] et al.; Touchi (I) 4 Dotaka Zn) N: Geometrical relationship with the metal surface emitted to Ryo 7E Mixed contact with corrosive substances and neutralizing agents may be caused by these factors.
This is to show the parts that do not corrode in N, where carbonate, etc. is sufficient for corrosion protection.
゜ Another cam is fii) Gold in the Akatsuki Furnace! The temperature of the irises is 2 times the temperature. If the metal surface temperature exceeds 400 degrees Celsius, the progress of this heart-warming effect will become more rapid, so keep the metal surface temperature below 400 degrees Celsius. Therefore, the combustion heat of waste is transferred to the boiler, When recovering heat exchanger as Sujino\, the boiler's heat transfer tube wall temperature must be maintained below 400°C.
As a result, the steam generated is 20 kg/c i, 3
00°C or below, '6-20k (] under operating conditions of practical equipment)
/ a (G, about 200 'C.C. With such medium-pressure steam, for example, when converting energy into electricity, the power generation efficiency is the highest) Ji
i/) Compared to heavy oil-fired thermal power generation, the cost of electricity is considerably higher.

This invention prevents the above-mentioned high-temperature corrosion and, as one result, provides a gum that can effectively generate pressure steam. For example, chromium and nickel are applied to the metal surfaces of incinerator parts made from a wide variety of metal sides, from carbon steel to heat-resistant alloys, etc., with a commercial ratio of chromium/nickel of 2/8 to 8. /2
A first layer of a mixture (I>) is first applied by melting, and then a second layer having a composition different from that of the first layer is coated thereon by melting.

Combustion power] members (J, made of steel, iron-based alloys, nitrogen-based alloys, etc. as necessary) - C-1 This invention - C (J, these 42 materials 1. Nittaruk 1-1 has a strong affinity and good heat resistance.
The first layer of the aluminum-based mixture is applied to the surface of the incinerator member (formed by spraying 4 pieces, mixture < 7). %
It consists of the following other elements: The chromium to nickel ratio of the compound (1) is set at 20/'S~80, 20 because it has good durability against the heating cycles of incense with 84). The corrosion resistance of Plasman R4, which is often used as 207/80' (-1/1, 207/80' (-1/1), and 207/80'(207/80') (containing ene), is within the above range. For example, 50/'v OI,'; how to add more chromium, and the element 3 and 4, which takes advantage of the chromium properties of a mixture of the two, further increases strength, [110 resistance, and oxidation resistance. Typical examples include 2A, tantalum, molybdenum, tangenone, )nolge, and silicon.

) A second layer with better edibility is formed on top of the first layer.

One second layer is composed of a mixture of materials (I>30-70%,
and at least 51 types of alkaline substances or 7 ceramics
Formed by 0-30%h. Mixture in the second layer (■)
(If it is not more than 30%, the affinity of the second L:ri for the first layer will be insufficient and the relationship between the first layer and the second layer will be poor.) This tendency is especially noticeable with alkaline substances.On the other hand, if the alkaline material is not more than 309f), the corrosion resistance of the second tang is insufficient (5).

In the present invention, as shown in (e) above, the components of the first layer and the resistance.

According to the investigation of the present inventor, it may be possible to start by coating the first layer with a second layer made of a material with better properties. Surprisingly, heat resistance up to about C is required, but surprisingly, the second layer is not the same as the above. Even if a foam layer made of ceramics containing a substance is used, there is no problem of peeling and cracking, and there is no significant difference in performance between the two people mentioned above. Mixture with the weight ratio of 7:3 to 3:7gY or 7':3-〇:5 ・Second decoy-C
It turned out that the same thing happened. However, when considering heat resistance at higher temperatures, such as 800 to 1000°C, the second layer may have corrosion resistance with the first layer components.
There is less risk of peeling etc. when using a mixture with '31.

In addition, ceramics are added to the top layer as a corrosion-resistant material.
In order to achieve such white benign properties at higher temperatures, a third layer made of ceramics is formed on top of a second layer made of the first layer components and ceramics. Rudoyoi 9. In this case, if the remix in the second layer is not 30%, the affinity between the second and third layers will be insufficient and there is a risk of peeling between the two layers due to thermal history.

Further, for good bonding between both layers, it is preferable that the resimix used for the second layer and the third layer be substantially the same.

Although plasma spraying is a typical method, it is useful for forming a dense branch covering layer that is useful for corrosion resistance. It is also possible to mix hydrogen to cause -CM'i conversion@ and reduction of 1jφ.

Ceramics that can be used in this invention include silicon, aluminum, magnesium, calcium, oxides such as zirconium 1X, silicon, small crystals, carbides such as titanium, silicon,
There are at least 51 types of nitrides such as aluminum and aluminum, but aluminum oxide is extremely representative.

It is sufficient that each layer used in this invention is mixed at the time of bath application to form a sufficiently uniform layer, but it is of course possible to obtain a more uniform layer by preparing a uniform mixture of alloys, etc., before thermal spraying, if desired. is easy to obtain and is generally preferred.

In the present invention, a first layer and a second layer having an intermediate composition are interposed between the material B and the second layer, or between the first layer and the third layer if there is a third layer. However, DanoΔ and each +j”'I etc.:
1 j1: further intermediate i between +t>'i of composition
14 (6) In this way, it is generally expected that the durability will be improved due to thermal cycles.

・J to the yj method of the second invention, for example, when the furnace starts operating, IIc) J3J, and ash etc.
831, E L/ (Mu, I have already found the right), the norkaline substance V, i containing the alkali 1-1 substance 7'E reacts with 1 lci to C neutral lAr 1 J fire ( By preventing high d, λl1jS corrosion on the gold surface, or by preparing the metal surface in advance (from any mixture such as f4 real ceramics or ceramics) l\, -tsukel, etc. /, f coating layer is :;j(crystal C
oxidation, corrosion due to IS temperature Cσ ru I C, f or (
,1,lIc1 etc.Alkali metal salts, heavy metal salts q9 ash or 1/',j, In case of severe high-temperature corrosion, it exhibits monophagous property in C non-rich. Also, a coating consisting of a mixture of substantial sefmitsku lamda and alkyl sex materials! In the case of t'N (, 1), this layer develops corrosion resistance due to the formation of neutral silica (1).
Mother! A jt! ! If you're a gold person, you won't be able to eat the highest quality of food.

4- As for the fluoralkaline substances, all those that can fully exhibit the above-mentioned AJ song should be used, or some kind of C or C, etc. should be used, but among them, carbonates of carbonates of metals and alkaline earth metals and alkali citrates should be used. C is a representative salt of alkali metals and alkaline earth metals.
Na, Ni, Ca, or M! At least one type of carbonate of J'X is used, and from the viewpoint of anticorrosion performance and cost, thulium carbonate is most suitable, and the alkali silicate is typically ptrium silicate, nonoriulium X, or lithium. It is true. Ru.

In the above description, the field of application of the present invention was typically explained as being a combustion furnace, but it goes without saying that the present invention can also be applied to various parts exposed to high-temperature gases including HC.

Hereinafter, the present invention will be clarified by Examples, but the present invention is not limited thereto.

For example, the rolling of an alloy steel (SCMV4) consisting of 2.2% of aluminum, 1% of charcoal, 0.15% or less of carbon methane (both % of riverside) and the balance of iron. 30mm long and 50mm wide from the board
A large number of plate-shaped test pieces with a thickness of 1 mm and a thickness of 1 mm were cut out, and each test material was subjected to various types of 7J treatment, and then an 811J good test was performed.

+1A! iQ 4/3 charge of 10,000 (people) (575 laps of Zoramasma bathing (using steps) as i%t5Q gokas Al-1 ゛ 60, Helium \ 40%, (Irage b volume %
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2000 ampere current (used in q, 1. Membrane good J On! m X
50 The area of Koda is also one--knee Q'+; 1. Place this coating (the number of letters) on the test piece.
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30% steam, Cox 10'-'0, [1c-
2'l0C)Q l1f)In, SOz 20 Df
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5x△1; There is a refined C of Sky Father. 'The test piece was placed in the HG air furnace and the surface temperature was maintained at 4[:00QC7].Test) 1t', /): 30X to be tested
5 Q 5 faces other than the surface with an area of 1nill (
Yo aluminum boo (sekkutsu) G! 3. i, hif common phase; intermittent type) marriage 1 no (ko J-ri, funeral 3 meals 4'),
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]%, jthorium 38%, potassium, ? .

5%, 1st 61%, + J, 2% r chlorine 2゜1%, total A 1.1%, water content 0.1% (both Φm%) - C and the rest is ↑ Combine with the above original thread and -C
It is oxygen.

L・1 meal test is up to 10 fXX under the above conditions.
SCI＼, which does not require coating for chemical education up to 1 minute.
4V'lchi1-8'! We went to the back together. h
Man! The tip of the l tip is 100 No. 100 (examination test)) 1 person is placed in the heart furnace, and after completely barging the no. Test piece by little brushing! , 'ij's ashes were removed and ○ '3 Q6's hekiwa methylene teramin was added as an inviter.
? 2 (8 moves 9/Q j-;Cj)
Soak for 4 minutes at temperature -C for 30 minutes to remove the so-called scale from the test piece. After performing a removal process, washing with water and drying, the car star was determined to be 1 flJ, and compared with a heavy metal that had been previously determined at 3JL before carrying out the corrosion resistance test, so-called weight reduction was determined. Figure 1 shows this 71111
This is a diagram showing the results of the f-sa test (Mura 41 Senka test days,
In general, Φnl is the weight loss (I/'iJ effective surface area 1 cm2) of the test piece.

Also, the line numbers in the diagram are test) -! 1 number is 11,)
1 shows the difference in the content of the coating layer, and each number is especially written below. Use j and C.

Test piece]: SCiνIV4 steel test J-i without coating layer
2:SC,\/IV 45iff Moon's Upper Ladder 1st Layer 1
-'' Moonitzur alloy (20% Cr - to 80%: )
ε62 hard 2C0.50% 1mm nickel alloy (2
0% CI・-8c%, ゛＼: 1) Add a mixed layer of 509δ to the plasma melting village with a height of 17 and 150μ each. 〉Goshita 2, Exam 1'? ', 3: S C\・i V 'l record)
(O's) -, try (: σage 12 and the same first layer, u) 2
Layered Normik 5) ○ So O, Ia jj 4\
-Ni tsu '/ /shi 〈) ia (20%
Cr -80% kii 50% i kneading
M(l l,
Ta.

Test piece'l:sc! YAV4>Oka+A -j 2 (first layer, second layer (J, same as test specimen 3, third decoy one layer alumina was coated with a 50 μm loaf by plasma cutting).

Test piece 5: The same first layer as test piece 2 was applied on top of the SCMV4 steel plate, and the second layer was coated with alumina plasma (J
, 50μ 17mm C coated 4° test, q tip 6: S Ci~, /lV4 Kuboji material's 2 (, 2, 1st layer is chromium niggle (do) O% Cr
-50%\1), moxibustion] In two layers, a mixture of 30% alumina and 70% chromium-nickel alloy (50%0r-b○%\1) was plasma melted into QJ and 'lC') 0μ 119 of SL 7.

Test Hough: SC\iV4 construction material ± (first layer is chromium-niracle alloy (85%0r-15%\l), second layer is alumino 30-6, chromium-nickel alloy (50% CI) -50%\: ()70% mixture 1
Each plate was coated with a thickness of 100μ by laser cutting.

Test, Specimen 8: Chromium in the first layer of SCMV4 steel material
KuijjL-nickel alloy (20%0r-10%S1-7
0% Nl), 2nd layer) Normina 30♀6, Ri 1'' MuNickel alloy (50
%(1,r-50%\1i)70♀6 situation compound, f us? (Each sword caused 2100μ of y゛,♂?
I did it.

1st doi G) 14j, 'l' indicates J, sea urchin is not coated for anti-corrosion C, and weight 'I(3'
, 'ij-Amount of straw corrosion 1i along with the vertical vortices between the walls j)
・) Human gland or this: J, I am five! JF in vermilion? 18 between the first j lii; eating habits (yo 1.511
1111 or more, in contrast to this, Mizumoto 1betsu is included, anti-corrosion /-
(The test piece radius j2.3 on which two effective coating layers were formed,
ll, 5°6 (j, quick decrease or almost r, z (f
liJ 〒)] Capacity 7. 1, 6 under class
- Irregular L +: 157 Meals are inconsistently demonstrating the effects of the present invention 1
(J(The strip 7℃ is the first layer of chromium ○ content or the scope of this defense is chewed 0 people) 'cL, the coating layer peels off, I
Dear LIi (As in the second test piece 8, if the first layer (other than chromium, nitrogen, or tertiary element) contains as much as 10%, the coating layer will peel off, resulting in It does not show any anti-corrosion effect.

Furthermore, instead of test piece 2 & Koi CNra2C○3, N
A25LQ3 was used to prepare one tuna test piece 9 and a test piece 5. A similar test piece 10 was prepared using a mixture of alumina and Na in place of aluminium; CO3 weighting ratio of 1:1. When a corrosion resistance test was conducted, test pieces 2-9 and 9 obtained the same results as test pieces 5.

[BRIEF DESCRIPTION OF THE DRAWINGS] [Yu'] Section 1: J is a graph showing the *i'j beam of the example.

Claims (1)

[Claims] 1) Chromium and nickel are added on a metal surface exposed to high-temperature gas containing HCl at a chromium/nickel weight ratio of 2/8 to 2/8.
A method for preventing corrosion, comprising forming a first layer of a mixture (I) containing 8/2 and a second layer having a composition different from that of the first layer thereon by thermal spraying. 2) The method according to claim 1, wherein the second layer comprises, by weight, 30% to 70% of mixture (I) and 70% to 30% of at least one alkaline substance. 3) The method according to claim 1, wherein the second layer consists of 30-70% mixture (I) and 70-30% ceramics by weight. 4) The method according to claim 1, wherein the second layer consists essentially of ceramics. 5) The second layer is substantially ceramic by weight ratio of 70 to 3
The method according to claim 1, comprising 0% and 30-70% of alkaline substances. 6) The method according to claim 3, wherein a third layer made of ceramic is formed on the second layer. 7) The method according to claims 1 to 5, wherein the mixture (I) contains 3% by weight or less of other elements in addition to chromium and nickel. 8) Claims 1 to 6 in which the thermal spraying is plasma spraying.
The method described in section.