JPS6250455A - Coating method with ceramic - Google Patents

Abstract

PURPOSE:To obtain a tough ceramic coating layer having high adhesion, superior heat, corrosion and wear resistances and high hardness by thermally spraying a composite material consisting of ceramics and a polymer on a surface to be processed. CONSTITUTION:The surface of a material to be processed is ground according to the thickness of a coating layer to be formed and it is roughened by blasting or other method. After an underlayer is preferably formed by thermally spraying composite Ni-Al powder or the like, a composite material consisting of ceramics such as Cr2O3, Cr2O3-SiO2, other metallic oxide, TiC, other metallic carbide, ZrB2 or other metallic boride and a polymer such as polypropylene resin or silicone resin is thermally sprayed with plasma, a flame or the like. The surface of the resulting ceramic layer is treated with a pore sealing agent such as epoxy resin to seal the pores and the coated material is subjected to finish working to prescribed dimensions.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the Invention (Field of Industrial Application) The present invention relates to a method of applying a robust ceramic coating. More specifically, the present invention relates to a method of applying a ceramic coating that is harder and has better corrosion resistance and wear resistance than conventionally used ceramic coatings.

(Prior Art) Some valves installed in petroleum refineries, petrochemical equipment, etc. handle high-temperature fluids or fluids containing corrosive components or solid particles, and are operated under high differential pressure. It is used under harsh conditions. For example, hydrorefining equipment for petroleum fractions handles aqueous solutions containing large amounts of hydrogen sulfide and ammonia, as well as small amounts of highly corrosive halogens. The differential pressure between the inlet and outlet is approximately 50 Ky/cr
! This control valve is being used under conditions of G, and due to corrosion of the solution and damage to the inner valve due to corrosion, the sealing performance (no leakage) when fully closed deteriorates in a short period of time, and the control ability is lost. This will have a negative impact on product quality and equipment safety, making it necessary to replace the inner valve. By the way, conventionally, (1) to prevent corrosion and wear of the inner valve of a control valve used under high differential pressure or corrosive atmosphere,
In general, the metal material Stellai) (Co-Cr-W-Nb
A stainless steel inner valve with stellite welding is available.

However, as mentioned above, even if the control valve is coated with stellite to increase its hardness under severe conditions, corrosion and erosion are observed, the amount of leakage when fully closed is large, and the control characteristics deteriorate, making it difficult to withstand long-term use. No.

Even with a new inner valve that has been welded with stellite, the leakage will greatly exceed the control valve's specified leakage value (less than 0.01% of the rated value) within a few months, and the original purpose of the control valve, the control function, will be lost. It is necessary to purchase and replace the same type of valve stem and valve seat each time, and managing them is troublesome, tidy, and expensive.

(2) In order to provide the valve with corrosion resistance and wear resistance, conventional coatings of nickel, cobalt, or tuff-based carbide by self-fluxing alloy thermal spraying (JISH8303) have been used to coat the inner valve. There is. In this method, a thermal spray coating is applied to the necessary parts of a base material (stainless steel material or carbon steel material), and after the thermal spraying, the coating is heated and melted at a temperature of approximately 1000 to 1100 DEG C. to be welded to the base material.

The feature of this method is that the thermal spray coating has no pinholes and is corrosion resistant.
Although it is good as a wear-resistant coating, the disadvantage is that the coating is heated to high temperature and melted after thermal spraying, which causes distortion, alteration, and shrinkage of the base material.

Therefore, when spraying a self-fusing alloy, a considerable amount of dimensional allowance is required in the base material. When reprocessing is required for repair, this method causes further distortion, alteration, and shrinkage of the base material, making it difficult to restore it to its original shape, so it is only used when creating new pieces.

(3) As mentioned above, when a hard coating is applied to a valve stem or valve seat using self-fusing alloy thermal spraying or welding, even if the coating becomes worn out or damaged, it is difficult to repair it.

Even if the shrunken base metal is restored to its original shape by weld overlay or self-flux alloy spraying, machining costs and material costs will increase.1. Economically, it is determined by year.

In addition, when applying Stellite coating to extend the durability of the inner valve, which lasts about 2 to 3 months, it is possible to add tungsten carbide as an additive to increase wear resistance, but ammonium hydroxide, hydrogen sulfide, etc. unsuitable for environments involving the handling of

(Problems to be Solved by the Invention) The present inventors have conducted various tests and research to obtain a valve that does not have the above-mentioned problems and can withstand long-term use even under harsh conditions. This problem can be solved by using a specific ceramic coating on the inner valve of the valve, and the method of applying this ceramic coating can be used not only for valves but also for applications under such harsh conditions. They discovered that the method can be applied to other items used in public transport, and obtained the following results.

However, conventional ceramic spraying has problems with airtightness due to the porosity of the ceramic itself, and it was thought that ceramic coatings could not be used for items that require airtightness, such as valves, but contrary to expectations, this problem was solved. It turns out that it can also be solved.

(B) Structure of the invention (means to solve the problem) In order to achieve the above object, the present invention is characterized by: 1. A composite material made of a ceramic material and a polymer is thermally sprayed onto the surface to be processed. , a method of applying ceramic coating.

It has as a configuration requirement.

The present invention also provides a method for preventing corrosion and wear on the surface of a member, which comprises thermally spraying a composite material of a ceramic material and a polymer onto the surface to be machined.

It provides:

The details of this technology will be explained below.

(1) Machines and parts targeted by the method of the present invention The method of the present invention includes (al) Valves having a metallic inner valve, such as spherical valves, angle valves, butterfly valves, diaphragm valves, ball valves, gate valves, It can be applied to Z-type valves, etc., and is particularly applicable to the contact surface (abutment surface) of the control valve seat (control valve seat) where controllability is required during use, and its vicinity, but it can also be applied to other parts of the valve as necessary. may also be applied. The material of the inner valve can be metal, for example, stainless steel, but carbon steel, cast iron, etc. can also be used. The inner valve can be made of iron or steel, but it can also be made of other metals.

(b) The present invention is applicable not only to valves but also to robustness, especially corrosion resistance.
It can be applied to any metal article that requires corrosion resistance and wear resistance. Examples include pumps, engines,
Examples include parts for combustion equipment, turbines, etc.

(2) Next, a method for applying a ceramic coating according to the method of the present invention will be explained.

However, although we will mainly discuss the case where a valve is selected as the object to be constructed, the same applies to cases where other machines or parts are the object.

(a) Overview of the ceramic spraying process Before ceramic spraying, the processed surface of the workpiece (base material) is first ground according to the thickness of the coating layer, and the surface is cleaned and roughened using the Plast method. It is preferable to perform metal thermal spraying as the base thermal spraying, and after performing ceramic thermal spraying as the final thermal spraying, the ceramic surface is first subjected to sealing treatment and finally polished to a specified size.

Further, it is preferable to perform cermet thermal spraying as an intermediate thermal spraying between base thermal spraying and finishing thermal spraying.

(b) Machining of the base metal surface (including blasting) Grinding of the machined surface of the base metal is performed so that it will have the specified dimensions when it is finally polished and finished, and the thickness to be ground is determined by the thickness of the coating. The amount depends on the thickness of the layer, usually 5 to 2000μ
m1 is particularly ground to a thickness of about 50 to 1000 μm. Surface cleaning using the Plast method degreases the surface of the base material, removes dirt,
In order to
In particular, abrasive materials with a grain size of +20 to +80 (e.g. alumina, silica alumina grains, etc.) and roughening of the surface using the plasto method are used to increase the surface area and improve bonding with the coating layer. The abrasive material, for example, ≠ ≠ 10 to 220, especially Φ10 to 60 particles (for example, alumina, silica-alumina grains, etc.), is ground by a conventional method with a grinding material of 3 to 20 Kp/c! degree, preferably 6
This can be done by blowing an air stream of Ky/cr&. The degree of surface roughening is preferably 40 to 200 μmRz.

(c) Base thermal spraying-Afi, N1-Cr-Fe-Afi, Ni-Mo
- A metal material in the form of a wire, powder or bare metal, such as an Afi mixture, is thermally sprayed onto the work surface using a gas combustion flame or a plasma arc flame. Particularly preferred metal materials are nickel-based materials, especially Mo-Afi-Ni mixtures (Mo2
~6%.

Afi3-8%, remaining N1)t or Afi-Ni mixed paste U3-15).

(d) Intermediate thermal spraying It is preferable to perform intermediate thermal spraying between the base thermal spraying and the final thermal spraying because it improves corrosion resistance and provides a buffering effect. Intermediate thermal spraying uses a powdered or cord-shaped composite material made of a mixture (cermet) of the metal material and ceramic material mentioned above, and is thermally sprayed using a gas combustion flame or plasma flame. Essential ceramic coatings, especially for imparting corrosion and wear resistance, such as AflzOa, CrzOa, ZrOz, TiO
2゜CrzO3-5iOz, Al1zoa-TiOz
, CrzO"510g - Using powdered, corded or linear ceramic materials such as metal oxides such as TiC, carbides such as TiC, ZrC, CrC, CrC-NiCr, or borides such as CrB and ZrBs, a gas combustion flame is used. Alternatively, it is sprayed onto the work surface using a plasma flame.A suitable ceramic material is Cr2031CrzO3-Si.
(h(SiOz 2-10%, remaining Cr203).

In the method of the present invention, 1 to 20% by weight of the ceramic material is added to the ceramic material.
Polymers or resins such as polyethylene, polyolefins such as polypropylene, polyvinyl esters such as vinyl acetate and vinyl laurate, polymethyl acrylate, polymethyl methacrylate, polyacrylic acid carbonate, fluororesins, polyesters, polyamides , polyimides, phenolic resins, area resins, melamine resins, furan resins, unsaturated polyester resins, epoxy resins, silicone resins, polyurethane resins, xylene resins, toluene resins, etc. are mixed and sprayed.

These solid resins are preferably in the form of fine powder (for example, about 0.1 to 10 microns). When a polymer is added to a ceramic material and thermal sprayed, the hardness of the resulting ceramic layer is about 1.5 times or more than when no polymer is added, and the wear resistance is improved. The polymer prevents excessive oxidation of the sprayed coating and still does not leave carbon-like residue in the coating.

It is preferable that the base sprayed layer, intermediate sprayed layer, and final sprayed layer all have a thickness of 2 to 1,500 μm, especially about 10 to 500 μm, and the total thickness of these layers is 5 to 20 μm.
00 μm1, particularly preferably about 20 to 600 μm. Particularly preferable thicknesses of the base sprayed layer, intermediate sprayed layer, and finish sprayed layer are each 5 to 150 μm 5 to 15
0 μm and 150 to 500 μm.

(f) Sealing treatment Next, sealing treatment is performed on the sprayed layer. In the pore sealing treatment, a pore sealant diluted in a solvent or vehicle is applied and dried in order to sufficiently impregnate the pores in the film. Those that dry slowly at room temperature may be cured by heating at a temperature below the allowable temperature of each sealant. Examples of sealants include barium sulfate, titanium oxide, clay, silica white, alumina white,
These include inorganic pigments such as calcium silicate and the aforementioned polymers or resins, which can be used in solvents or vehicles such as alcohols such as methanol, ethanol and octanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, mineral spirits, and naphtha. , turpentine oil, calpitols, cellosolves, boiled oil, water, etc. or dispersed therein. Particularly preferred sealing agents are silicone resins and furan resins.When airtightness is required, the surface of the film after sealing is ground and polished to the final dimensions using a grindstone, such as a diamond grindstone or a silicon carbide grindstone.

The sprayed coating thus produced has high hardness and excellent adhesion to the base material (for example, 300 Ky/d or more). When final dimensional precision is not required, the initial grinding or final polishing process can be omitted, and when airtightness is not required, the sealing treatment with a sealant can be omitted.

(Function) As described above, according to the method of the present invention, the hardness of the ceramic thermal spray coating is improved to nearly twice that of a general homogeneous ceramic coating, and the adhesion to the base material is also excellent. By applying this to parts that require wear resistance, corrosion resistance, etc. for use under particularly harsh conditions, it dramatically increases the service life of mechanical parts and makes equipment maintenance and management easier and more economical. It can be improved to the extent possible.

In addition, since the method of the present invention does not cause the ceramic coach-in effect, various inexpensive metals can be selected as the base material, and since it can be used for re-repair, the economical effect of construction is There is something.

For details on this point, please also refer to the description in the column (c) Effects of the invention.

(Example) [Part 1] An example in which the method of the present invention is applied to a valve will be described with reference to the drawings. FIG. 1 shows a longitudinal sectional view of a valve portion of an automatic control valve (spherical valve) (control mechanism parts other than the valve portion are omitted because they are directly related to the present invention).

In the figure, 1 is the valve body, 2 is the valve seat (seat ring), and 3 is the valve stem (
4 is a valve stem, 5 is a pin that fixes the valve stem 3 to the valve stem 4, 6 is a bonnet, 7 is a guide bushing, 8 is a gasket, 9.10 is a bolt that fixes the bonnet 6 to the valve body 1 . (The structure of the valve itself is the same as that of the conventionally known one, and its structure can be seen, for example, in "Latest Control System Series Volume 1 Instrumentation Control System" by Tamotsu Ishii, January 3, 1981.
For details, see pages 25 and 320-326 published by Denkishoin on the 1st, and pages 186-187 of "Chemical Engineering Handbook" published by the Chemical Engineering Association, published by Maruzen Co., Ltd. on May 10, 1964. ) The method of the present invention applies the above-mentioned ceramic coating to at least the contact surface of the inner valve of a conventionally known valve.

In Figure 1, the areas where the ceramic coating is applied are as follows:
The spotted surface of the valve stem 3 and the spotted upper inner surface of the valve seat 2. Specifically, this part was ground and pretreated using the Plast method to obtain a roughness of 90 μm (Rz), N1
-AQ composite powder (85% Ni, 115% Af)
Metal spraying was applied to a thickness of 5μ, and cermet spraying was performed to a thickness of 25μ with an equal weight mixture of the same N1-A, IL composite powder as above and CrzOa-polymethylacrylate resin mixed powder (resin powder 6wt%), and the same as above. Cr 203-polymethyl acrylate resin mixed powder was ceramic sprayed to a thickness of 200 μm, and an epoxy resin sealant was applied.
It was fired at 0°C and finally polished to the specified dimensions.

The valve shown in FIG. 1, whose inner valve was coated with ceramic in this manner, was used as a liquid level control valve. The liquid we handled contained 26wt% hydrogen sulfide, 11% ammonia, and 0% chlorine.
An aqueous solution of pH 9.3 containing 2 wt ppm, the valve has a flow rate of 251/hr and a pressure of 48 KP/citG.
, the differential pressure was 47 Ky/crlG, and the temperature was 38°C. The above control valve operated normally even after 12 months of operation.

Comparative Example 1 For comparison, a valve with the same structure as the valve of Example [Part 1] was used, except that Stellite welding was applied instead of the ceramic coating, and the liquid level was adjusted under the same conditions as Example [Part 1]. Used as a valve. Three months later, the valve stopped working properly and had to be replaced.

[Part 2] Ni-Afi-Mo composite powder (M.

5%, Afi 6%, remaining 1) using Ni), Cra
C in place of Oa-polymethyl acrylate resin mixed powder
r20a-51Ch-polymethyl methacrylate resin mixed powder (5ins 7%, resin 7ch, remainder 1) Crab
The same control valve as described in Example [Part 1] was prepared in the same manner as in Example [Part 1], except that s) was used and a phenolic resin sealant was used instead of the epoxy resin sealant. Ceramic coating is applied to the inner valve.

When this control valve was used under the same conditions as the example (1), it operated normally even after 12 months.

[Part 3] AnzOa-TiO2-polypropylene resin (
Example 1 was carried out in the same manner as Example 1, except that TiCh 8, resin 10%, remainder AfizOa) mixed powder was used, and barium sulfate sealant was used instead of the epoxy resin sealant. A ceramic coating was applied to the inner valve of a control valve similar to that described in Part 1].

When this control valve was used under the same conditions as in Example [Part 1], it operated normally for 11 months.

[Part 4] Instead of the CrzOa-polymethylacrylate resin mixed powder, CrC-NiCr-silicon resin mixed powder (Ni1
0%.

Example [Part 1] was carried out in the same manner as Example [Part 1], except that 10% Cr, 8% resin, and the balance CrC-) were used, and a silicone resin sealant was used instead of the epoxy resin sealant. A ceramic coating was applied to the inner valve of a control valve similar to that described in 1]. When this control valve was used under the same conditions as in Example [Part 1], it operated normally for 12 months.

[Part 5] A ceramic coating was applied to the inner valve of a control valve in the same manner as in Example [Part 1] except that cermet spraying was not performed as intermediate thermal spraying. When this control valve was used under the same conditions as in Example [Part 1], 10
It worked normally for months.

Comparative Example 2 Example [Part 1] except that Cr 203 powder was used instead of the CrOa-polymethylacrylate resin mixed powder
Cera and mink coatings were applied to the inner valve of the control valve in the same manner as above. When this control valve was used under the same conditions as in Example 1, it operated normally for 5 months.

(c) Effects of the invention The ceramic coating applied to the workpiece surface according to the invention is robust, the bond between the ceramic layer and the base material (workpiece surface) is strong, the ceramic layer has few pores, and is heat resistant and corrosion resistant. It has excellent hardness, corrosion resistance, and wear resistance, and high hardness. The workpiece can be made not only of stainless steel, but also of inexpensive carbon steel or cast iron. When performing metal spraying, cermet spraying, and ceramic spraying, the temperature of the workpiece is low, e.g., approximately 30 to 200°C, so distortion of the base material,
Almost no deterioration or shrinkage occurs. Further, the coating method according to the present invention can be easily carried out, and has exceptional functions and effects compared to conventional means.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional view of an example of a valve whose inner valve is coated with a ceramic coating by the method of the present invention. 1... Valve body 2... Valve seat 3... Valve stem 4...
・Valve stem 6...Bonnet agent Patent attorney Nagai 1) Hiroshi - Figure 1

Claims (1)

[Claims] 1. A method of applying a ceramic coating, which is characterized by thermally spraying a composite material made of a ceramic material and a polymer onto the surface to be processed.