JPH02149656A - Treatment method for thermal spray coating - Google Patents

Abstract

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

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method of treating metal spray coatings.

<Prior Art and Problems to Be Solved> It has been known for a long time to protect the iron surface electrochemically by coating the iron surface with a metal or an alloy thereof that has a greater tendency to ionize than iron.

For example, by coating the surface of steel with zinc or its alloy, the potential difference between iron and zinc is used to protect the steel by using zinc as a sacrificial anode.

One of the methods for coating the surface of steel materials with zinc or its alloy is a metal spraying method. This metal spraying is a method of melting a linear or powder coating material and spraying it at high speed to form a layered film of fine particles on the surface of the base material. They are classified into types such as arc type, plasma type, and explosion type. For general rust prevention, an arc type or gas type using a wire rod is used.

In either thermal spraying method, a film obtained from a metal less noble than iron, such as zinc or its alloy, serves as a sacrificial anode for the iron and protects the iron surface.

However, since zinc or its alloys in particular serve as sacrificial anodes, they corrode earlier than iron, resulting in the formation of white rust on the surface, which is very aesthetically unsightly.

It is generally believed that the lifespan of steel is proportional to the thickness of the zinc or zinc alloy coating on which it is coated, but in reality, thermal spray coatings are highly uneven and have air permeability (pinholes). Even if it is present, red rust will form on the iron base from the pinhole area.

Much research has been done to solve these problems. For example, a method has been proposed that after thermal spraying, epoxy resin, phenol resin, silicone resin paint, etc. is diluted with thinner and applied to seal the pores (Jun Hasui, Yokendo Publishing =
"Thermal Spray Engineering").

However, although this method appears to seal the bottle holes and coat them uniformly with the sprayed coating, the coating is thin and lacks durability, so the sealing effect deteriorates rapidly over time. The drawback was that it faded.

In particular, there was a problem in that white rust was significantly generated in a short period of time.

In addition, as another method, it is known to perform chromate treatment on the thermal spray coating (Japanese Patent Publication No. 6235831).
.

In this treatment method, there are safety and hygiene problems with chromium, and although short-term corrosion resistance is excellent, long-term durability is insufficient. Furthermore, some chromate treatments are not effective unless they are baked at a high temperature of 150 to 180°C.

In order to solve the problems of the prior art as described above, the inventors of the present invention conducted extensive research and found a method for protecting steel materials for a long period of time.

Means for Solving the Problems> That is, the present invention forms a thermally sprayed coating of a metal or an alloy thereof having a larger ionic tendency than iron on the surface of iron, and then coats the deposited layer after drying with a coating of 10%.
The present invention relates to a method for treating a thermal spray coating, which comprises applying a silane coupling agent to a concentration of ~50.000 mg/m'.

In the method of the present invention, examples of metals or alloys thereof that have a higher ionization tendency than iron that are thermally sprayed onto the iron surface include zinc, zinc-aluminum alloy, zinc-tin alloy, etc., and the shape is linear or Powder form is preferred.

In addition, in the arc type or vacuum arc type, for example, one wire is a zinc wire and the other wire is an aluminum wire, and by spraying the two wires at the same time, a zinc-aluminum pseudo alloy is formed on the surface of the material. Kotoshi (I can do it, but
If the alloy formed has a greater tendency to ionize than iron, it is naturally within the scope of the present invention.

In this case, the ratio of the two metals can be changed arbitrarily by changing the thickness of the wire.

In addition, in the method of the present invention, there are various methods for thermal spraying the metal or its alloy, such as a gas method, a plasma method, an explosion method, an arc method, and a vacuum arc method depending on the heat source for melting. You can. There are no particular conditions for thermal spraying; it can be carried out under the conditions commonly used in the past.

Furthermore, the silane coupling agent used in the method of the present invention generally has the structural formula shown by and is classified into vinyl type, methacrylic type, amine type, epoxy type, mercapto type, etc. depending on the type of A. be done. The alkoxy group represented by OR is
It is hydrolyzed by moisture in an aqueous solution or in the air to generate silanol groups, which provide bonding properties to materials.

Specific examples of the silane coupling agent include vinyl silane coupling agents such as vinyltriethoxysilane and vinyltris(2methoxyethoxy)silane;
Methacrylic silane coupling agent such as methacryloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2
Amine-based silane coupling agents such as -(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane; 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl) Epoxy-based silane coupling agents such as ethyltrimethoxysilane; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, and the like.

It goes without saying that commercially available silane coupling agents other than those mentioned above can also be used in the present invention.

The silane coupling agent can be applied as it is or diluted with water or an organic solvent, but it is preferable to apply it diluted in order to form a uniform film on the sprayed surface and to control the amount of adhesion.

The silane coupling agent has an adhesion amount of 10 to 10 after drying.
50.000mg/m', preferably 100-1,0
Immersion method, air spray method,
It is applied onto the surface of the thermal spray coating using a conventional coating method such as brushing.

The amount of silane coupling agent attached after drying is 10mg/m
If the amount is less than 50.000 mg/cm, the convex surface of the sprayed coating will not be completely covered, and white rust will occur from that area, making it difficult to achieve the desired effect of the present invention.
If the amount is more than m', the inside of the silane coupling agent film may peel off during processing, or the silanol groups generated by hydrolysis due to moisture may become insufficient, resulting in a decrease in adhesion to the thermal sprayed film and the adhesion. This is undesirable because it becomes impossible to balance the effects and economic efficiency associated with the increase in quantity.

After applying the silane coupling agent, the steel material may be left to dry at room temperature, or
It may be forcibly dried for about 30 minutes.

Thus, according to the method of the present invention, it is possible not only to protect the iron material, but also to prevent the formation of red rust from the pinhole portions of the thermal sprayed coating and the formation of white rust from the thermal sprayed coating itself, and the industrial value is extremely large. It becomes something special.

The details of the present invention will be explained below with reference to Examples.

"Part" or "%" indicates "part by weight" or "% by weight".

Example 1 A gas sprayed zinc coating of 50 μm was prepared on a 10 cm x 10 cm grid-blasted steel plate (surface roughness R2-, 70 μm) by a conventional method, and then an epoxy-based silane coupling agent [3-glycidoxypropyl-tripropylene] was applied. The aforementioned grid-blasted steel plate treated with a zinc gas spray coating was immersed in a mixed solution of 119 methoxysilane (trade name A187, manufactured by Nippon Unicar) and 97 n of ethyl alcohol, and after 1 minute, it was taken out and dried at room temperature. The amount of silane coupling agent deposited after drying was 850 mg/m''.

This steel plate was subjected to a comparative test.

Example 2 10cm x 10cm sandblasted steel plate (surface roughness R
，! =, 40 μm), a 50 μm thick gas spray coating of zinc-aluminum alloy was prepared by a conventional method, and then treated with the same epoxy-based silane coupling agent as in Example 1, and dried at 80° C. for 20 minutes. .

The amount of silane coupling agent deposited after drying is 30mg/
It was m'.

This steel plate was subjected to a comparative test.

Example 3 10cm x 10cm sandblasted steel plate (surface roughness R
, ', 40 μm) was coated with the same zinc gas sprayed coating 5 as in Example 1.
0 μm was prepared, and further a Ryomino-based silane coupling agent [
After drying a mixed solution of 13 parts of 3-aminopropyl-triethoxysilane (trade name A-1100 manufactured by Nippon Unicar) and 97 parts of methyl alcohol, the im value with 0) is 40.000.
It was applied with a brush so that it was mg/m'.

It was further dried at 110° C. for 20 minutes and subjected to a comparative test.

Example 4 10cm x 10cm sandblasted steel plate (surface roughness R
2ζ 40 μm), a vacuum arc sprayed coating of 50 μm of zinc was prepared by a conventional method, and an amine-based silane coupling agent [:N-2-(aminoethyl)3-aminopropyltrimethoxysilane (trade name A manufactured by Nippon Unicar Co., Ltd.) was applied. -112
0)] and 97 parts of methyl alcohol, the above-mentioned thermal sprayed steel plate was immersed for 21 L and dried at room temperature.

The amount of amine-based silane coupling agent attached after drying is 15
It was 0 mg/m'.

This steel plate was subjected to a comparative test.

Example 5 A zinc-aluminum pseudoalloy thermal spray coating of 50 μm was prepared on a 10 cm x 10 cm (grid plus) plate B (surface roughness R2' = 70 μm) by vacuum arc spraying, and a vinyl-based silane coupling agent [ Vinyl-tris-(β-methoxy-ethoxy)silane (trade name A-172, manufactured by Nippon Unicar)] was dried as a stock solution and the adhesion amount was 4.
It was air-sprayed to a concentration of 500 mg/m' and subjected to a comparative test.

Example 6 A zinc-titanium alloy thermal spray coating of 50 μm was prepared on a 10 cm x 10 cm grid-blasted steel plate (surface roughness R2″ = 70 μm) by vacuum arc spraying, and a methacrylic silane coupling agent [3-methacryloxy-propyl Methoxysilane (product name A-17 manufactured by Nippon Unicar)
4)) It was immersed in a mixed solution of 1 part of ethyl alcohol and 99 parts of ethyl alcohol, and after 1 minute it was taken out and dried. The amount of silane coupling agent adhered after drying was 15.000 mg/m'. This steel plate was subjected to a comparative test.

Comparative Example 1 In the same manner as in Example 1, a zinc gas sprayed coating was produced on a grid-blasted steel sheet, without being treated with a silane coupling agent,
It was subjected to a comparative test.

Comparative Example 2 In Example 3, a commercially available chromate solution was applied with a brush instead of the amine-based silane coupling agent, and 15
It was air dried at 0°C for 15 minutes. The amount of chromate film deposited after drying was 500 mg/m'. This steel plate was subjected to a comparative test.

Comparative Example 3 In Example 3, the same amine-based silane coupling agent solution was applied with a brush, and the amount of silane coupling agent adhered after drying was 65. All treatments were carried out in the same manner as in Example 3 except that the concentration was adjusted to OOOmg/m'.

This steel plate was subjected to a comparative test.

Comparative Example 4 All treatments were carried out in the same manner as in Example 4, except that the amount of the amine-based silane coupling agent deposited after drying was 7 mg/m'.

This steel plate was subjected to a comparative test.

Comparative Example 5 The same thermal spray coating as in Example 6 was prepared, but without silane coupling treatment, the epoxy resin having the formulation shown below was diluted by 50% with a solvent, and air sprayed to give a dry coating thickness of 20 to 30 μm. This board was used for testing.

(Epoxy resin paint) A Main agent Epoxy resin 15 parts Kizilol 25 Methyl isobutyl ketone 22.5 Titanium oxide 5 Calcium carbonate 7.5 B Hardening agent Polyamide resin 10 Kizilol 10 Isobutanol 5 The above epoxy resin is manufactured by Shell Chemical ■ Ebiko (trade name) #1001 (epoxy equivalent: 450,520) was used, and the polyamide resin was Tomide #210 (product name, manufactured by Fuji Kasei ■). Immediately before use, add 2 parts of curing agent to 75 parts of base resin.
5 parts were blended to obtain an epoxy resin paint.

The results obtained in Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1.

Note 1) Corrosion resistance (SST500H) According to JIS-5400, a cut was made with a razor to reach the base material, and a salt spray test was conducted.

After spraying salt water for 500 hours, the area occupied by white rust on the surface was observed.

[Evaluation] ◎ No white rust at all ○ White rust area within 5% △ White rust area 5-50% × All white rust Note 2) Corrosion resistance (SSTI O00H) Tested in salt water for 1000 hours using the same test method as Note 1) After spraying, the state of red rust on the surface was observed.

[Evaluation] ◎ No red rust at all ○ Red rust area within 5% △ Red rust area 5 to 50% × Full surface red rust Note 3) Warm water resistance (50℃ x IO days) Make a cut on the test board with a razor □ to reach the substrate. 50
It was completely immersed in deionized water at ℃ for 10 days and the surface condition was observed.

[Evaluation] ◎ Completely good with no white rust or red rust ○ Spotted white rust (within 5%) △ White rust occupancy rate 5-50% (2013) A cut was made on the test plate using a razor, and the surface condition was observed after being exposed to the coast of Okinawa for two years.

Evaluation criteria are the same as Note 3).

It is clear from the test results in Table 1 that according to the method of the present invention,
Compared to those obtained by conventionally known methods, it not only protects the surface of the iron substrate, but also has a significantly superior effect in preventing the formation of red rust from pinholes in the thermal spray coating and in preventing the formation of white rust in the thermal spray coating. there were.

Claims (1)

[Claims] Forming a thermal spray coating of a metal or its alloy that has a greater ionization tendency than iron on the surface of iron, and then applying a silane coupling agent so that the coating amount after drying is 10 to 50,000 mg/m^3. A method for treating a thermal spray coating characterized by: