JPS59107070A - Corrosion preventing method - Google Patents

Abstract

PURPOSE:To prevent the corrosion of a metal to be exposed to high temp. gas contg. HCl by spraying a mixture contg. Cr and Ni at a specific rate on the surface of the metal and further forming a corrosion resistant layer having the compsn. different from said compsn. by spraying. CONSTITUTION:The 1st layer of a mixture I contg. Cr and Ni at 2/8-8/2 by weight of Cr/Ni and the 2nd layer having the compsn. different from the compsn. of the 1st layer thereon are formed respectively by spraying on the surface of a metal such as a structural material or the like to be exposed to high temp. gas, such as combustion gas, contg. HCl, whereby the corrosion of the metal is prevented and the heat energy of the high temp. gas is made utilizable. The above-mentioned 2nd layer consists preferably of 30-70wt% the mixture I and 70-30% at least 1 kind of alkaline material or ceramics, or the substantially equal effect of corrosion resistance is obtd. as well by using said layer consisting substantially of ceramics 70-30% ceramics and 30-70% alkaline material.

Description

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

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 proportion of incineration is increasing due to the depletion of land for landfill. As the amount of waste increases, the amount of plastic contained in the waste also increases, and the energy contained in the waste increases, making effective recovery of the waste an urgent problem. From this point of view, in recent years, various devices have been researched and developed that effectively utilize the calorific value of the 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. There is C. In these devices, corrosive gases such as HCJ, C10, and SOx are present in the high-temperature combustion gas, and ash consisting of unburned substances and alkali metal salts, heavy metal salts, and other solid substances produced as a result of combustion is inevitable. coexist with each other.

Metals exposed to such high-temperature combustion gas have ash on their surface (q@L and l-I in the atmosphere to which the metal is exposed).
It is known that when CJ coexists, the corrosion (high-temperature old corrosion) becomes extremely severe, and the corrosion rate increases as the altitude increases. That is, the surface temperature of the metal is 300
When the temperature exceeds ℃, high-temperature corrosion occurs, and when the temperature exceeds 400℃, corrosion becomes especially severe. Among the commercially available practical metal materials, only a few special high-grade metal materials can withstand this high-temperature corrosion. do not have.

Conventionally, the following two methods have been used to protect metal materials 1 of fuel reactors from this type of high-temperature corrosion.

One is to neutralize the acidic corrosive gas generated during combustion by reacting with an alkaline substance such as soda carbonate, or to neutralize the acidic corrosive gas generated during combustion with an alkaline substance such as PVC. There is a method of using a so-called neutralizing agent in the combustion atmosphere, which is supplied into the furnace together with the waste.

However, although these methods are mainly effective for treating corrosive debris in combustion scum, they are not effective against high-temperature corrosion that occurs when ash is present on the metal surface and HCj coexists in the atmospheric gas. However, this method was insufficient as a corrosion prevention method. In other words, carbonates, etc. cause high-temperature corrosion due to various factors such as the geometrical relationship between the furnace internal structure and the metal surface on which high-temperature corrosion occurs, the flow state of combustion residue, and the mixed contact state of corrosive gas and neutralizing agent. This is because there are parts of the metal surface that do not reach a sufficient barrier for corrosion protection.

Another method is to lower the temperature of the metal material in the combustion furnace. That is, this high-temperature corrosion progresses more rapidly when the metal surface temperature exceeds 400°C, but the metal surface temperature is kept below 400°C. Therefore, when the combustion heat of waste is recovered and recycled as steam in a boiler, waste heat boiler, etc., the temperature of the heat transfer tube wall of the boiler must be increased to 400°C.
As a result, the generated steam must be maintained at a design value of 20 ka/c, 300°C or less, and 16 to 20 kq/c under the operating conditions of practical equipment.
The temperature will be around 0℃. This kind of medium pressure Suji IX'
For example, in the most common case of C', when energy is converted into electricity, 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 for preventing the above-mentioned high-temperature corrosion and, as one result, making it possible to obtain high-pressure steam economically.

In this invention, metal surfaces exposed to HCj and gases, such as incinerator members made of a wide variety of metal materials from carbon steel to heat-resistant alloys, are coated with chromium and nickel depending on the required heat resistance. A first layer of mixture (i) containing nickel in a 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 coated thereon by thermal spraying.

Combustion furnace components are usually made of various Ti4 materials, iron-based alloys,
Since it is made of nickel-chromium alloys, etc., in this invention, the first layer of the nickel-chromium 11-based mixture, which has a sufficiently strong affinity for these materials and has good heat resistance, is formed on the surface of the incinerator member by thermal spraying. . Mixture (I) consists of nickel and chromium alone or both; 3% to 1
Contains the following other elements. The reason why the chromium/nickel ratio of the mixture (1) is set to 20/80 to 80/20 is that the adhesion with the base material has good durability against heating → noise. 20/80 is often used on the blasting side, but to further improve corrosion resistance, for example 50/50 is used within the above range.
It is better to increase the amount of chromium, such as 150. Further, other elements are added to take advantage of the characteristics of the mixture of the two to further improve strength, acid resistance, oxidation resistance, etc., and typical examples include di-AI, tantalum, molybdenum, tungsten, aluminum, and silicon.

Since the first layer of the mixture (1) does not have sufficient corrosion resistance as a combustion furnace member exposed to 1-IC, this study found that the first layer of the mixture (1) has sufficient affinity for the first layer and has better fi'4 corrosion resistance. A second layer is formed over the first layer.

One second layer contains a mixture by weight (I>30-70% and at least one carbonate layer of alkali metals and alkaline earth metals).
Seeds (hereinafter collectively referred to as "carbonates") or ceramics 7
Formed from 0 to 30%. If the mixture (I) in the second layer is not 30% or more, 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 it will be difficult to form a stable second layer. There are many things. On the other hand, unless the carbonate or ceramic is above 3096 JJ, the durability of the second layer is generally insufficient.

As mentioned above, the present invention started from coating the first layer with the second layer made of the components of the first layer and a material with better corrosion resistance. Surprisingly, in cases where heat resistance up to about 600°C is required, such as in municipal waste incinerators, it is surprisingly possible to use ceramics such as thick aluminum or 30% of this as a second layer different from the above. It was found that problems such as peeling did not occur even when using a layer substantially made of ceramics containing a first layer component of less than 50%, and there was no significant difference in performance between the above-mentioned two materials.

However, considering the heat resistance of the whole or part at high temperatures such as 800 to 1000°C, peeling etc. may occur if the second layer is made of a mixture of the first layer components and corrosion resistance. There are few errors. Furthermore, when ceramics are used as the top layer as a corrosion-resistant material, in order to satisfy the corrosion resistance at higher temperatures, it is necessary to
Preferably, a third layer made of ceramic is formed on top of the layer.

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 hot fat.

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

Can it be used in this invention? For 8-spraying, various thermal spraying methods can be used as required, and Torinari blaster thermal spraying is a typical method, and is suitable for forming a dense coating layer that is useful for corrosion resistance. In addition. It is also possible to reduce the oxide film by mixing hydrogen into the inert scum used in plasma spraying or the like.

The Hiramixes used in this invention include oxides of silicon, aluminum, magnesium, calcium, zirconium, etc., carbides of silicon, boron, titanium, etc., nitrides of silicon, boron, aluminum, etc., and at least one of them.
Seeds are used, with aluminum oxide 'cum' being very typical.

The layers used in this invention may be mixed during thermal spraying to form a sufficiently uniform layer, but it is of course possible to form a uniform mixture of alloys or the like before thermal spraying if desired. Generally, it is preferable because it is easy to coat layers.

In the present invention, a first layer and a second layer having an intermediate composition are interposed between the P4 material and the second layer, and when there is a third layer, between the first layer and the third layer, respectively. An intermediate shield may be interposed between the base material and each layer and a layer having an intermediate composition, and if this is done, it is generally expected that the durability against thermal cycles will be improved.

According to this investigation method, for example, H
Even if CJ iJ3 and ash approach the high-temperature metal surface, the carbonate in the pre-existing carbonate layer of sufficient Φ will not react with HC.
, i to form neutral salt ash to prevent high-temperature corrosion on the metal surface, or substantially ceramics or ceramics and chromium already present on the metal surface.
The coating layer made of a mixture with nickel etc. is oxidized at high temperatures,
It exhibits extremely excellent corrosion resistance against corrosion caused by HCJ at high temperatures or severe high-temperature corrosion when 14CJ and ashes of alkali gold N salts, heavy metal salts, etc. coexist, thereby preventing high-temperature corrosion reaching the base metal surface. Does not occur.

As the carbonates of the alkali metals and alkaline earth metals, at least one carbonate such as IVHI is used for Na, K, Ca, and Al, or Torihata 1! /J Carbonic acid from the viewpoint of food performance J5 and cost? 1~RIU\\ is optimal.

In the above, the field of application of the present invention was typically explained using a combustion furnace, but it goes without saying that the present invention is also applicable to various members that are exposed to high-temperature gas including HCJ.

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

Example: Alx 2.2%, Molybdenum 1%, 0.15% or less carbon (weight%)
A large number of test plates with a width of 4 mm and a width of 4 mm were cut out, and each test material was coated with various methods and then subjected to a corrosion resistance test.

The test + J tl coating method uses a commercially available plasma melting DJJ machine and uses 60% argon and helium 4O as the injection gas.
%, (all % by volume) was used under the conditions of a DC voltage of 40 holes and a discharge current of 800 amperes, and was coated on one surface of the test material with an area of 3 Q mm x 5 Q mm. This coating flow test A corrosion resistance test was conducted using the material as a test piece.For the corrosion resistance test, ash collected from an actual garbage incineration furnace was uniformly spread over the surface of the test piece on which a coating layer had been formed using a tubular electric furnace, and water vapor was heated at 30°C inside the pipe. %, 00210%, l
-I CJ 100011111m, SO2201
11)m (Ifh is also M%) Composition of remaining air The test piece was placed in a tubular electric furnace through which a high-temperature atmospheric gas flows, and the surface humidity of the test piece was maintained at 600°C. Five sides of the specimen other than the surface with an area of 30 x 5 Q mm to be tested were protected from corrosion by alumina fine powder A3 and H&fibular insulation. The composition of the ash collected from the garbage amortization furnace and placed on the surface of the test piece was 7.1% aluminum, 3.8% sodium, and 2.8% potassium.
, Calicilam 14.5%, Magnesium 1°5%, Iron 6
．． 1%, silicon 15.2%, chlorine 2.1%, total sulfur 1
．． 1%, water content 0.1% (all % by volume), and the remainder is mainly oxygen (C, which bonds with the above elements).

Corrosion resistance test is best 10 times C7J according to the regulations mentioned in 1- below.
For comparison, SCfl/l V 4 without coating was also tested. After conducting the corrosion resistance test, the test piece was taken out from the electric furnace after completely purging the N2 scum in the tubular electric furnace and kept at room temperature/[5! After cooling, the ash on the surface of the test piece was removed by nolacing, and 0.5% was added as an inhibitor.
The test piece was immersed in a hydrochloric acid aqueous solution (8 wt% l-1 (1)) containing hexamethylenetetramine at a reduced temperature for 30 minutes to remove corrosion products from the test piece, followed by a so-called school removal process, washed with water, dried, and then weighed. The so-called weight loss was determined by comparing the test hand weight measured in advance and r d3 before conducting the corrosion resistance test.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 There is a weight loss of the test piece (II 1 g/effective surface area 15 C).

In addition, the line numbers in the figure are the test piece numbers and also indicate the differences in the content of the coating layer, and a coating layer with the structure described below is used for each number.

Test piece 1: SCMV4 steel without coating layer Test piece 2:
The first layer of chromium-nickel alloy (2
0%Cr -80%Ni) second layer weight 2C0350% and chromium-nickel alloy (20%Cr -80%N1) 50%
The mixed disease was coated with a thickness of 150 μm each by plasma spraying.

Test piece 3: Test material 2 on top of SCMV4 steel
The second layer was coated with a mixed layer of 50% alumina and 50% nickel alloy (20%0R-80%N1) to a thickness of 100μ each using plasma.
.

Test piece 4: 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 on the SCMV4 steel material.

Test piece 5: SCMV4 steel was coated with the same first layer as in test J12 and second layer of alumina to a thickness of 50 μm by plasma spraying.

Test I-1' 6: On top of S CM V 4 steel material,
The first layer is a chromium-nickel alloy (50% cr-b).

%N1), 30% alumina in the second layer, 50%Cr -50%Nr>
Each 7C% mixture was coated to a thickness of 100μ.

Test piece 7: On top of the SCMV/l8i4 shrine, the first layer is a chromium-nickel alloy (85% Cr-15% N1), the second layer is alumina 30%, and a chromium-nickel alloy (50% Cr-50%). A mixture of 70% Ni) was coated with a plus 7 melting knife to a thickness of 100μ each.

Test piece 8: Chromium-silicon-nickel alloy <20%Qr-10%5i-70%N1) on the SCMV4uA material in the first layer, 30% alumina, chromium-nickel alloy (50%Cr-) in the second layer A mixture of 50%N1) and 70% was coated by plasma spraying to a thickness of 100μ each.

As shown by the line in Figure 1, in Test H without anti-corrosion coating, the weight did not decrease but increased as the corrosion progressed (i is I), and if this line remained as it was and moved to 11F, The corrosion rate during the first year is 1.5 l'I1m or more.

In contrast, the test piece wires 2.3, 4, and 5°6C, to which the present invention was applied and a coating layer effective for corrosion prevention was formed, showed almost no weight loss and were below the limit value for the number of measurements. In other words, there is almost no corrosion, proving the effectiveness of the present invention. In addition, in test piece 7 shown by line 7, if the chromium content in the first layer exceeds the range of the present invention, the coating layer will peel off. If a third element other than nickel, such as silicon, is used in an amount as high as 10%, the coating layer will peel off, resulting in no anticorrosion effect.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the results of Examples. Patent applicant Toyo Engineering Co., Ltd. Agent
Hitozu Akiramine Shoiri Q
@&'j (a) Procedures Amendment Written December 28, 1980, 1st stop' Relationship with the case of the person who filed the patent application Address of the patent applicant: 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo Name
Toyo Engineering Co., Ltd. Representative Sakura 11
Masao 4, Agent address: 6-12fftlO-5, Higashifunabashi, Funabashi City, Chiba Prefecture.
Date of amendment order 4 Not voluntary 6, Number of inventions increased by amendment None 7, Full text subject to amendment Correction M Book 1, Title of invention Corrosion prevention method 2, Claims 1) HC,, f Chromium and nickel are added to metal surfaces exposed to high-temperature gases containing
The first layer of the mixture (1) containing from /8 to 8/2, the "-
A second layer having a composition different from that of the first Fj is formed by dissolving the two layers respectively.
A corrosion prevention method characterized by: 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 1-. 7) The method according to any one of claims 1 to 5, wherein the mixture (1) contains less than 3% of other elements than chromium and nickel. 8) Claims 1 to 6 in which the molten copper is brass melted.
The method described in section. 3. Detailed Description of the Invention The present invention relates to a method for preventing corrosion of metals containing 1-IC and exposed to high-temperature gases such as combustion gases. 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 exponential increase in waste, the amount of plus deck contained in the waste also increases, and the energy contained in the waste also increases, making its effective recovery an urgent issue. From this perspective,
In recent years, various research and development have been conducted on devices that effectively utilize the calorific value 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, HCJ and CJ are contained in high temperature combustion gas.
2, S. In addition to the presence of corrosive gases such as Metals exposed to such high-temperature combustion gas will undergo extremely severe corrosion (high-temperature corrosion) if ash adheres to the surface and HCJ coexists in the atmosphere to which the metal is exposed, and as the temperature rises. It is known that the M4 eating rate increases. In other words, high-temperature corrosion occurs when the surface temperature of metal exceeds 300°C, and corrosion becomes particularly severe when the surface temperature exceeds 400°C. There is no material that can withstand high temperature corrosion. Conventionally, C
The following two methods have been used to protect this. One is the acidic corrosion that occurs during combustion (the scum is neutralized by reacting with an alkaline substance such as a carbonate sorter, or the alkaline substance is used when burning waste such as PVC that generates l-I CJ). There is a method of using a so-called neutralizing agent in the combustion atmosphere, which is supplied into the furnace to remove waste and However, C was insufficient as a corrosion prevention method for high-temperature corrosion that occurs when there is some ash on the metal surface and l-I Cj coexists in the atmosphere. Due to various factors such as the geometric relationship with the metal surface where corrosion occurs, the flow state of the combustion gas, and the mixed contact state of the corrosive gas and the neutralizing agent, carbon dioxide may be applied to the metal surface where high temperature corrosion occurs. This is because salt, etc., forms in areas where the corrosion resistance does not reach a sufficient temperature.Another method is to lower the temperature of the metal filler in the combustion furnace.In other words, this high-temperature corrosion If the surface temperature exceeds 400 degrees Celsius, the progress will become more intense, so keep the metal surface temperature below 400 degrees Celsius.Therefore, if the combustion heat of waste is recovered as steam in a boiler, waste heat boiler, etc. Den P!Cylinder type temperature 400'
There must be 14 strings from C to F, and II! i The photogenic gas generation rate is 20 kg/am at the design h1 value, 300°C or less, and the operating condition of the practical equipment is 16-209/cmG, 20
Let's heat 4C to 0℃ culm degree. With this medium-pressure steam, for example, when the energy is converted into electricity, which is the most common method, the electric power generation rate is considerably lower than that of the latest heavy oil-fired thermal power generation, and the power generation rate is also high. The present invention provides a method for preventing the above-mentioned high-temperature corrosion and, as one result, making it possible to use high-pressure steam economically. In this invention, metal surfaces exposed to l-I CU gas, such as baked 7JL furnace members made from a wide variety of metal materials, from carbon steel to heat-resistant alloys, depending on the required heat resistance. chromium and nickel at a chromium/nickel weight ratio of 2/8
~Mixture containing 8/2<1. ) is first coated by thermal spraying, and then a second layer having a composition different from the first layer is coated thereon by thermal spraying. Combustion furnace members are usually made of various steel materials, iron-based alloys, nickel-chromium alloys, etc., as necessary (in this invention, we use potassium chloride, which has a sufficient affinity for rice, and has good thermal properties). -1- Nikka Luke

[The first layer of com-residue compound is formed on the surface of the 7J1 furnace member by FIJ. The fbj compound (1) consists of only nickel and comb, or contains 3% or less of other elements based on the combination of both. The chromium/nickel finish of mixture (1) is 20/80 to 80/20
This is because the adhesive with the base material has good durability against heat recycling. Plasma spraying is often used for 2°/80, but the second layer when containing mixture (I) is In order to increase the corrosion resistance of steel, it is recommended to increase the amount of chromium within the above range, such as 50/50.Additionally, other elements can be used to bring out the characteristics of a mixture of the two, further increasing the strength and strength.
Added to improve acid resistance, corrosion resistance, etc.
Typical examples include tantalum, molybdenum, tungsten, aluminum, and silicon. Since the first layer of mixture (1) does not have sufficient corrosion resistance as a combustion furnace member exposed to l-I CJ, the present invention uses a second layer that has sufficient affinity for the first layer and has better corrosion resistance.
A layer is formed over the first layer. One second layer contains 30 to 70% by weight of mixture (I) and at least one alkaline substance or 70% of ceramics.
Formed from ~30%. The mixture in the second layer (I> is 3
If it is not more 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 occur.
It is often difficult to form layers. This tendency is particularly noticeable for alkaline substances. On the other hand, unless the alkaline substance or ceramics is 30% or more, #4 corrosion resistance of the second layer is generally insufficient. The invention started by coating the first layer with a second layer consisting of a better Ufl, but according to the investigation of the present inventors, it has been found that in particular, in steam-generating municipal waste incinerators, temperatures of up to 600°C Surprisingly, when heat resistance up to There is no problem of peeling such as 11!1 even when using a layer of :3 to 3 near, preferably 7:3 to 5:
2nd mixture of 5! It was found that the same applies to Fj. However, for example 800 - = 10 in total or in part
Considering heat resistance at higher temperatures such as 00°C, it is easier to peel if the second layer is made of a mixture of the first layer components and a corrosion-resistant material.
There is little risk of occurrence of f. In addition, when ceramics are used as the top layer as the corrosion-resistant material 1, in order to satisfy the corrosion resistance at higher temperatures, a third layer made of ceramics is formed on the first layer components and a second layer made of ceramics. It's good to do that. In this case, if the ceramic content in the second layer is not more than 30%, the second and third layers
There is a risk that the layers may not have sufficient affinity and peeling may occur due to the heat history between the two layers. Furthermore, for good bonding between both layers, the ceramics used for the second and third layers are preferably substantially the same. Various methods can be used for the thermal spraying used in the present invention as required, but plasma spraying is particularly representative and is useful for forming a dense coating layer that is useful for corrosion resistance. In addition. It is also possible to reduce the oxide film by mixing hydrogen into the inert Shinai bamboo used in plasma spraying and the like. Ceramics that can be used with this product include oxides of silicon, aluminum, magnesium, calcium, and zirconium, carbides of silicon, boron, and titanium, silicon,
There are nitrides such as boron and aluminum, and at least one of them is used, but aluminum oxide is extremely typical. It is sufficient that each layer used in this invention is mixed at the time of melting to form a sufficiently uniform layer, but it is of course possible to prepare a uniform mixture of alloys etc. before thermal spraying if desired. In general, this is preferable because it allows a layer of various types to be obtained. 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. Material and each layer and inside 1. 11 of layers with CI-like composition! An intermediate layer may be further interposed in υ, and in this way, it is generally expected that the durability against thermal cycles will be improved C2! Ru. According to the method of this invention, for example, when the furnace starts operating, t
l CJ d5 and high ash content) 1g on the highest metal surface
Even if there is a sufficient amount of alkaline sludge already present, the alkaline substance in the layer containing the substance reacts with IIC to form C neutral salt ash, preventing high temperature corrosion on the metal surface, or by preventing high temperature corrosion on the metal surface. The coating layer consisting of substantial ceramics existing on the metal surface, or a mixture of ceramics and chromium, nickel, etc., is exposed to high temperature C, and high temperature C)-
By exhibiting extremely excellent corrosion resistance against corrosion caused by IC, / or severe high temperature corrosion when ash such as LI CJ doal 7J coexists with metal salts and heavy metal salts,
In addition, in the case of a coating layer that is essentially a mixture of ceramics and alkaline substances, this layer has the effects of both forming neutral salt ash and exhibiting corrosion resistance, resulting in high temperatures reaching the surface of the core material. Corrosion occurs. All of the alkaline substances that fully exhibit the effects described in 1 above can be used, and at least one of them is used, but carbonates of alkali metals and alkaline earth metals are particularly suitable. Typical examples are alkali metals and alkali silicates, and carbonates of alkali metals and alkaline earth metals include Na, Ca, and
, or with a small amount of carbonate such as Mg, fl>11f! Helium carbonate is usually used from the viewpoint of anticorrosion performance and cost, and alkali silicate is the most suitable for silicic acid salts.
Typical examples include lithium, potassium, and lidium. In the above, the field of application of the present invention was typically explained using a combustion furnace. It can also be applied to members, etc. The present invention will be clarified by examples below, but the present invention is not limited thereto. .Alloy steel with 15% or less carbon content (%) and the balance being iron (30 mm long and 50 mm wide from a rolled plate of SCMV4>,
A large number of plate-shaped test pieces with a thickness of 4 mm were cut out, each test material was coated with various methods, and then a corrosion resistance test was conducted. The test material was coated using a commercially available Zoramas spraying machine, using a mixture of 60% C argon, 10% helium (both by volume) as a spray sludge, and applying a DC voltage/IO pol l-
, used at a discharge current of 800 amperes, and the test material 3
One surface with an area of 0m+nx50H was coated. Eleven corrosion resistance tests were conducted using this test material as test pieces. The corrosion resistance test was carried out using a tubular electric furnace.The surface of the test piece on which the coating layer had been formed was uniformly coated with the collected ash from an actual waste incineration II furnace (1) + 330% water vapor and 10% CO2 inside the tube.
, lIcJlooooppm , 502201111m
(All percentages by volume) The test was carried out by placing the test piece in a tubular electric furnace through which a high-temperature atmospheric gas with a composition C' of the remaining air was flowing and maintaining the surface temperature of the test piece at 600'C. The area of 30x50mm to be tested of the specimen is
The material was protected from corrosion by aluminium fine T5) 13 and fibrous heat insulating material. In addition, Jinkayaki fdl
The composition of the ash collected from the furnace and placed on the surface of the test piece was 7.1% aluminum, 3.8% puttrium, 2.8% potassium, 115% calcium, 1.5% magnesium, 6.1% iron. Silicon: 15.2%, chlorine: 2.1%, total A: 1.1%, water content: 0.1% (both medium ω%), and the remainder is mainly oxygen bonded to elements listed in 2. It is. The corrosion resistance test was carried out under the conditions described above for a maximum of 10 days, and for comparison, SCMV/l without 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, taken out from the electric furnace, left to cool in the air for about 5 hours, and then brushed to remove ash on the surface of the test piece, and then treated with 0.5% inhibitor. The specimen was tested by immersing it in an aqueous hydrochloric acid solution (8% by weight HC) containing hexamethylene detramine at room temperature for 30 minutes, followed by a so-called descaling treatment to remove 1"l of corrosion products, washing with water, drying, and then measuring the results manually. The so-called weight loss was determined by comparing the test weights measured in advance before conducting the corrosion resistance test.Figure 1 shows the results of this corrosion resistance test. The axis is the weight loss (m (1/effective surface area 15 cTl?) of the test piece.The M number of the line in the figure still indicates the difference in the content of the coating layer at Test No. 11 CC, and each number is shown below. A covering layer with the following configuration was used. Test II @ J11: A first layer of chromium-nickel alloy (20% Cr - 80% Ni) 2nd layer weight 2CO3
A mixed layer of 50% chromium-nickel alloy (20% Cr-80% N1) of 150 μm each was coated by plasma spraying. Test J'F 3: On top of SOM V4 steel, the same 1st E'f as test piece 2 and 50% alumina in the 2nd layer.
, chromium-nickel alloy (20%Cr -80%N1)
The 50% mixed layer was coated with a blastema solution to a thickness of 100 μm each. Test C4: 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 on the SCMV4 steel shrine. Test piece 5: On top of the SCMV4tll material, the same first layer as test piece 2 was applied, and the second layer was coated with alumino to a thickness of 50 μm using plasma melting. Test piece (3: The first layer was applied on top of the SCMV4 steel [-J
Munickel alloy (50%Cr-50%Ni), 2nd
The layers were coated with a mixture of 30% alumina and 70% chromium-nickel alloy (50% OR-50% N1) to a thickness of 100 microns each by plasma spraying. Test piece 7: On SCMV4 steel, the first layer is chromium-nickel alloy (85%Cr-1Ei%Ni>), the second layer is 30% alumino, chromium-nickel alloy (50%Cr-50%Ni>7)
0% mixture was coated with a thickness of 100 μm each by blaster spraying. Test piece 8; SCMV4WA on top of the first layer of chromium-silicon-nickel alloy (20%Cr-10%5r-70%N1), second layer of Noflumino 30%, chromium-Niracle alloy (50%)
/I' b O%N + ) 70% mixture was coated with a thickness of 100 μm each by plasma spraying. As shown by the line in Figure 1, in Test 11 where no anti-corrosion coating was applied, the amount of corrosion increased with time; The corrosion rate for one year is 1.5 mm or more.In contrast, the test piece wires 2, 3, 4, 5゜6r, which were coated with a 41-effective g1 layer for corrosion prevention by applying bright light, have a weight of The reduction is at least within the measurable limit.In other words, there is almost no corrosion, proving the effectiveness of the present invention.Also, in the test specimen 7 indicated by line 7, the chromium content in the first layer is If the size exceeds the scope of the present invention, the coating layer will peel off, and similarly as in test piece 8, the first FIkm chromium,
If a third element other than nickel, such as silicon, is contained in an amount as large as 10%, the coating layer will peel off, resulting in no corrosion-preventing effect. Roughly speaking, test piece 9 J3 was obtained by using a-3 in test piece 2, and Na2sL03 was used instead of Na2Co: +, and alumino and tJa2 were obtained in place of alumina in test piece 5.
4 using a 1:1 mixture of cO3 medium! In addition, when similar corrosion resistance tests were conducted using Test C10, similar results were obtained for Test Pieces 2 and 5. , Indication of matter 1'1, Special KF Application No. 216679, September 2, 1982, Title of invention: Corrosion Prevention Law 3.7 ■Name to correct 4, Agent 61-12-10-5, Higashi-Funabashi, Funabashi City, Chiba Prefecture, Amendment Date of order: 3J, 1982] 29B66 Subject of amendment 1d (Full text d5 and p to certify power of attorney, Column 7
, amend the contents of Supplement J- as shown in the attached sheet and submit one power of attorney. 1. Indication of the incident 1982 Sweat Patent Application No. 216679 2
, Title of the invention: Corrosion prevention method 3, Amendment request 4, Agent: 6-12-10-5, Higashiguchi () Bridge, Funabashi City, Chika Prefecture, Date of amendment order: Voluntary amendment) 6.711L ! Full text for details 7? lIi Correct content statement OIm as per the attached sheet d3 Correction j[Pull. Full text Revised details 1, Title of invention Corrosion prevention method 2, Claims 1) IC, i! Chromium and nickel are added to the metal surface to be reduced to high-temperature scum containing
A method for preventing corrosion, comprising forming a first layer of a mixture <i) containing 7'B. 2) The second layer contains mixture (I) 30% to 70% by weight ratio
The method according to claim 1, comprising 70% to 30% of at least one nonorkaline 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 claim 1 and 5, in which the warm 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 melting is plasma melting
The method described in section. 3. Detailed Description of the Invention This invention relates to a method for preventing corrosion of metals exposed to high-temperature residues such as combustion gases, which contain the present invention (IC). Recently, the amount of waste containing chloride from abandoned industrial facilities at home, such as garbage containing plastics such as PVC, has increased dramatically, and how to dispose of it has become a problem. There are two types of disposal methods: landfilling and incineration, but with the former, the proportion of incineration seems to be increasing due to the depletion of land for landfills due to pollution problems such as soil contamination. Plastic Φ contained in waste is increasing
Due to the increase in the amount of energy contained in waste, the energy content of waste is also increasing, making effective collection of waste a pressing issue. From this point of view, in recent years various research and development have been carried out on devices that utilize the heat of the high-temperature combustion residue generated when chloride-containing substances, such as the above-mentioned wastes, are incinerated, and some of them have already been put into practical use. ing. In these devices, J5 contains HC in the high-temperature combustion residue.
J, CJ2, S. Corrosive residue such as X is present, and unburnt material d5
There is also the inevitable coexistence of alkali metal salts, ferrous metals, redundant salts, and other solid substances produced as a result of combustion. Metals exposed to such high-temperature combustion residue have ash attached to their surfaces and l-I CJ in the atmosphere to which the metal is exposed.
! It is known that the corrosion (high-temperature corrosion) becomes extremely severe when these coexist, and the rate of corrosion increases along with the analogy of hot jets. In other words, high-temperature corrosion occurs when the surface temperature of the metal exceeds 300°C, and corrosion becomes particularly severe when the surface temperature exceeds 400°C. There is no other material that can withstand 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 and neutralize the acidic and corrosive scum generated during combustion with an alkaline substance such as soda carbonate, or to incinerate the alkaline substance together with the waste when burning waste that produces HCJ such as PVC. There is a method 1] in which a so-called neutralizing agent is supplied into the combustion atmosphere. However, all of these methods mainly involve right-handed movement in the disposal of erodible debris in the combustion gas, but when ash is deposited on the metal surface and HCJ coexists in the atmospheric debris, C was considered insufficient as a corrosion prevention method against the high-temperature corrosion that occurs. In other words,
Due to various factors such as 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 residue and the neutralizing agent, the metal surface where high-temperature corrosion occurs This is because there are parts where carbonate and the like do not reach a sufficient amount for corrosion protection. Another method is to lower the temperature of the metal in the combustion furnace. In other words, this high-temperature corrosion accelerates when the metal surface temperature exceeds 400°C, so keep the metal surface temperature below 400°C. In case of recovery, the boiler heat exchanger tube wall temperature is
The resulting steam must be kept at a temperature below 20 kg/ci, 300'C.
The following is a practical gFl operating condition of 16-20 kg/
cnG, 200℃ culm 11 days. In such medium-pressure steam, for example, when energy is generated as electricity, which is the most common method, the power generation efficiency is lower than that of the latest heavy oil-fired photovoltaic power generation, and the photoelectric cost is 1~1. This invention prevents the above-mentioned high-temperature corrosion, and as one of its results, it is possible to effectively use high-pressure steam.
'There are some that provide rh. In this invention, chromium and nickel are applied to metal surfaces exposed to HCJ gas, such as incinerator parts made from a wide range of metal materials, from carbon steel to heat-resistant alloys, depending on the required heat resistance. A first layer of the mixture (I) containing chromium/nickel in a weight ratio of 2/8 to 8/2 is first coated with a hot melt, and then a second layer having a composition different from the first layer is coated thereon with a hot hot coat. do. 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 (I) consists only of nickel and chromium, or (contains 3% or less of other elements based on the total of both J).The chromium/nickel ratio of the mixture (I) is 20/80 to 8.0. /20 is selected because it has good durability against heating cycles of the base material. 20/80 is often used in Norasma thermal spraying, but the second layer when containing mixture (I) In order to further increase the corrosion resistance of 50150 balls, etc., it is recommended to increase the amount of chromium within the above range.Additionally, other elements can be used to bring out the properties of a mixture of the two, further increasing the strength and strength.
It is added to improve acid resistance, oxidation resistance, etc., and typical examples include niobium, tantalum, molybdenum, tungsten, aluminum, and silicon. The first layer of mixture (I), which is a combustion furnace member exposed to HC, does not have sufficient corrosion resistance. A good second layer is formed on the first layer.One second layer is made of 30-70% by weight of mixture (i) and at least one alkaline substance or lamizulf.
Formed from ~30%. The mixture (I) in the second layer is 3
If the temperature is less than 096, the affinity of the second layer to the first layer is insufficient, and the peeling between the first layer and the second layer is difficult and it is difficult to form a stable second layer. There are also many. This tendency is particularly noticeable in alkaline materials. On the other hand, unless the content of alkaline substances or ceramics is 30% or more, the corrosion resistance of the second layer is generally insufficient. The present invention started by coating the first layer with a second layer made of the components of the first layer and a material with good corrosion resistance, as described in j-e above, but according to the investigation of the present inventors, in particular, In cases such as steam-generating municipal waste incinerators, where heat resistance up to at most 600°C is required (surprisingly, a second layer different from the above is made of ceramics such as C aluminum). Alternatively, even if a layer substantially made of ceramics containing 30% of the unvortexed first layer component is used, problems such as peeling will not occur.
There is no significant difference in performance between the two mentioned above, and furthermore, a mixture of substantial ceramics and an alkaline substance in a weight ratio of 7:3 to 3, preferably 7:3 to 5:5 is used as the second material. It was found that there was also C in the layer as well. However, considering the heat resistance of the whole or part at higher temperatures such as 800 to 1000'C, it is better to form the second layer or a mixture of the first layer components and the corrosion-resistant material as it may cause flaking etc. Less is. 5. Corrosion resistance When using ceramics as the top layer, in order to satisfy the corrosion resistance at higher temperatures, a third layer made of ceramics must be placed on top of the second layer made of ceramics. It is best to form layers. in this case!
'! If the ceramic content in 2tFf 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. Further, for good bonding between both layers, it is preferable that the ceramics used for the second layer and the third layer have substantially the same carbon content. For thermal spraying, various thermal spraying methods can be used as needed (noplasma thermal spraying is a typical example and is useful for forming a dense coating layer with excellent corrosion resistance.J3
It is also possible to mix hydrogen into the inert scum used in ゜shirasumama melting etc. and mix it with the ('l') element of the C oxide film. Oxides such as aluminum, magnesium, calcium, and zirconium, carbides such as silicon, boron, and titanium, silicon,
There are nitrides of boron, aluminum, etc., and at least one of them is used, or aluminum oxide is very representative of -C. It is sufficient that the layers used for this purpose are mixed at the time of thermal spraying to form a sufficiently uniform layer, but it is of course possible to prepare a homogeneous mixture of alloys, etc., before thermal spraying, if desired. A layer similar to I+7 is generally preferred. In the present invention, a first layer and a second layer of 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, respectively. An intermediate layer may be interposed between the base material and each layer and a layer having an intermediate composition, and in this way, it is generally expected that the durability against thermal cycles will be improved. According to the method, for example, 1
Even if lcJJ3 and ash approach the high-temperature metal surface, the pre-existing alkaline material in the layer containing a sufficient amount of alkaline material reacts with IC,j and becomes neutral salt ash. J-Ri, which prevents high-temperature corrosion on metal surfaces.
Alternatively, a coating layer consisting of a mixture of substantial ceramics or ceramics, nickel, etc. that already exists on the metal surface, or high temperature (oxidation, corrosion due to HCj or HC), alkali salts, heavy metals, etc. It can withstand severe high-temperature corrosion when ash such as salt is present; 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. The above-mentioned alkaline substances can be all-C, as long as they can fully exhibit the above effects, and at least one of them is used, but also alkali metals and alkaline substances such as carbonates, alkaline silicates, etc. Among the carbonates of alkali metals and alkaline earth metals, at least one type of carbonate such as Na, Ca, Mg, etc. is typically used.From the viewpoint of anticorrosion performance and cost, Sodium carbonate is most suitable, and aluminum silicate is typically sodium silicate or sodium or lithium. 1n, but of course the present defense is
It can also be applied to various types of kidnappings. The following examples clearly illustrate the present invention, but the present invention is not limited thereto. Example Base metal m consisting of 2.2% chromium, 1% molybdenum, 0.15% or less carbon (all weight%) and the balance iron
(SCMV4) 30mm long and 5Qmm wide from the rolled plate
A large number of plate-shaped test pieces having a thickness of 4+++ m were cut out, and each test material was coated with various methods and then subjected to a corrosion resistance test. The coating method for the prototype material was to use a commercially available blaster sprayer, and use a mixture of 60% argon and 40% helium (both by volume) as the injection gas under the conditions of a DC type In of 40 volts and a discharge current of 800 amperes. 30m of test material
A single surface with an area of mx 5 Qmm was coated. A corrosion resistance test was conducted using the test material of rice coated with this coating layer as Test J'1. The corrosion resistance test was carried out using a tubular electric furnace.Ashes collected from an actual garbage incinerator were uniformly spread on the test 11 surface on which a coating layer had been formed, and the inside of the tube was heated with 30% water vapor, 10% CO2, and H(,f).
The test piece was placed in a tubular electric furnace in which a high-temperature atmosphere having a composition of 20 ppm (volume %) and the remaining air flowed, and the surface temperature of the test piece was maintained at 600°C. Test H tested 30
Five surfaces other than the surface with an area of x50 mm were protected from corrosion by fine alumina powder and fibrous heat insulating material. d5, the composition of the ash collected from the garbage incinerator and placed on the surface of the test piece was 7.1% aluminum, 3.8% sodium, 2.8% potassium, and 14.5% calcium.
, magnesium 1.5%, iron 6.1%, silicon 15.2
%, chlorine 2°'196, 1.1%, moisture content 0.
1% (both 1a%), and the rest is mainly above] L
There is an acid type C that combines with an element. The corrosion resistance test was carried out under the conditions described below for a maximum of 10 mouths.For comparison, the SCM4b test was conducted without coating. In test C, after carrying out the corrosion resistance test, N2 gas was completely purged in the tubular electric furnace, and the test piece was taken out from the electric furnace from C and left to cool in a room for about 5 hours, and then the ash on the surface of the test piece was removed by brushing, and the ash was further removed with an inhibitor of 0.5 The specimen was immersed for 30 minutes in a hydrochloric acid aqueous solution (8 wt. The so-called ff1ffl reduction was determined by comparing the amount of N in the test piece measured in advance before conducting the corrosion resistance test.Figure 1 shows the results of this corrosion resistance test. The number of days, the vertical axis is the test [1 weight loss (m (1/right effective surface h'115C
b). In addition, the line numbers in the figure are the test piece numbers and indicate the differences in the content of the coating layer between the old and the same test piece, and a coating layer having the structure described below was used for each number. Test piece 1: S CM V 4'4'A without coating layer
4J test Ji2: 1st layer chromium on top of SCMV4 steel
Nickel alloy (20%Cr -80%[N1)iir'
! A mixed layer of 50% 2fFJffi2CO3 and 50% chromium-nickel alloy (20%Cr-80%N1) was coated with a thickness of 150μ each by plasma cutting. Test G3: On top of the SCMV/l steel material, the first layer was the same as test specimen 2, and the second layer was a mixed layer of 50% alumina and 50% nickel alloy (20%Cr -80%N1). Each plate was coated with a thickness of 100μ by plasma spraying. Test piece 'I: On SCMV4 steel, the first and second layers were the same as test piece 3, and the third layer was coated with alumina by plasma spraying to a J7 thickness of 50 μm. Try Jli'fl-! + 5: SCMV4m material 1 was coated with the same first layer as in test j42, and the second layer was coated with alumina to a thickness of 50 (1) by plasma spraying.
．． :. The test halo ° S CM V 4 steel was coated with a chromium-nickel alloy (50% Cr-50% N1) in the first layer and 30% alumina in the second layer [J Moon nickel alloy (50% C)]. -50%N1)7
The 0% mixture was coated with a thickness of 100 μm each by blasting with a blaster. Test piece 7: SCMV4flli! On top of the material, the first layer is chromium-nickel alloy (85% Cr-15% Ni>, the second layer is 30% alumina, chromium-nickel alloy (50% Cr-50% N1)7
0% mixture was coated with a thickness of 100 μm each by plasma cutting. Test C8: Chromium-silicon-nickel alloy (20%0r-10%Si-70%N1) as the first layer on SCMV4 steel material, aluminum J' as the second layer
30%, Ri[J moonicle alloy (50%Cr-50%
A 70% mixture of N1) was coated with a thickness of 100 μm each by blaster spraying. As shown by the line in Figure 1, the weight of specimen-C, which has not been coated with anti-corrosion coating, decreases in weight, but the amount of corrosion increases with the passage of 8N. ,
The corrosion rate during the first year is 1.5 mm or more. In contrast, test H line 2.3 was applied to which the present invention was applied and a coating layer effective for corrosion prevention was formed. /1.5°6, there is almost no weight loss and it is below the measured nJ capability limit. In other words, there was almost no corrosion, proving the effectiveness of the present invention. In addition, when the chromium content of the first layer exceeds the range of the present invention, peeling of the coating layer occurs in test piece 7'c'' indicated by line 7; If a third element other than nickel, such as silicon, is added too quickly, such as 10%, the coating layer will peel off, resulting in no corrosion-preventing effect. Furthermore, in test J12, j also used 23L03 instead of UNa2CO3 (17 test piece 9, Jj Yohi test piece 5).
Smell - Alumino and Na2CO3 instead of C alumina
CI'' test using a mixture with a 1:1 ratio of 141
10, the same corrosion resistance test as J was conducted, and test piece 2 and test)'+! ') similar results were obtained for 1q. 4. Brief explanation of the drawings FIG. 1 is a graph showing the results of the example.

Claims (1)

[Claims] 1) Chromium 11 and nickel are added to the metal surface exposed to 8-temperature gas containing I+(, e) at a chromium/nickel weight ratio of 2/'8 to 8/2' (including The anticorrosion Ij method is characterized in that a first layer of mixture (I) is formed and a second layer having a composition different from the first layer is formed on top of the first layer by respectively melting q. 2) Is the second layer heavy? The method according to claim 1, consisting of a mixture (I > 30% to 70%) and at least 70% to 30% of at least one kind of alkali metal and alkaline earth metal carbonate salts. 3) The second layer consists of a mixture (i) of 30 to 70% and a ceramic of 70 to 30% in a small matrix ratio (see Patent 1if3).
The method described in Section 1 of IIIJ. 4) The method according to claim 1, wherein the second M consists essentially of ceramics. 5) The method according to claim 3, wherein a third layer made of ceramic is formed on the second layer. 6) The method according to claims 1 to 5, wherein the mixture (I) contains chromium, nickel, and 3% by weight or less of other elements. 7) Claims 1 to 6 in which the material is plastic
The method described in section.