JPH07116582B2 - Sealing method for thermal spray coating - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for improving heat resistance and corrosion resistance of a thermal spray coating.

(Prior art and its problems) The thermal sprayed coating of metal or ceramic has excellent wear resistance and is therefore widely used for mechanical parts and members including sliding parts such as pump shafts and bearings. It's starting to happen.

Furthermore, in recent years, the number of cases where mechanical parts and members are used not only at room temperature but especially at high temperature has also increased,
Accordingly, nickel-chromium alloys, zirconia (Zr
Thermal spraying materials with improved heat resistance and corrosion resistance, such as O ₂ ) and tungsten carbide (WC), have been developed.

However, many pores (total porosity 1 to 10%) are present inside the as-sprayed coating, and many pores reach the ground surface. Therefore, even if the thermal spray coating itself has excellent heat resistance and corrosion resistance, since the base material is exposed to the outside air through these pores, the base material is corroded and deteriorated in a high temperature or corrosive atmosphere, and eventually the parts and members are exposed. Leading to damage.

The method of filling the pores is called a sealing treatment, and as the sealing material, wax, vinyl resin, phenol resin, polyurethane resin or the like is used alone or in a mixture with a pigment. However, since these materials have a melting point or decomposition temperature of at most 200 ° C., the weight loss is remarkable at a high temperature, particularly in an atmosphere exceeding 200 ° C., and it is not possible to fill the pores reaching the substrate in the thermal spray coating.

Under the present circumstances, there is a great demand from the industrial world to develop a sealing material for a sprayed coating that is resistant to use in such a high temperature range and has corrosion resistance.

(Technical Means for Solving Problems) The present invention is a composition in which 100 parts by weight of polymetallocarbosilane, 10 to 200 parts by weight of a silicone resin and 10 to 200 parts by weight of an inorganic filler are dissolved or dispersed in an organic solvent. The present invention relates to a method for sealing pores of a sprayed coating, which comprises coating and / or impregnating the sprayed coating.

The polymetallocarbosilane used in the present invention comprises a carbosilane bond unit of the following (A) and at least one metalloxane bond unit of the following (B), (A): (In the formula, R ₁ and R ₂ may be the same or different and each independently represents an alkyl group having 1 to 4 carbon atoms, a phenyl group or a hydrogen atom.) (B): MO (wherein, M Represents at least one element selected from the group consisting of Ti, Zr, Mo, and Cr, and in some cases, at least a part of each element has at least one alkoxy group having 1 to 4 carbon atoms or a phenyl group as a side chain group. A polymer in which the respective bonding units of (A) and (B) are randomly bonded in the main chain skeleton, and / or at least a part of the silicon atoms of the bonding unit of (A) is the same as that of (B). It is a polymer in which a polycarbosilane moiety bonded to each element of the bonding unit through an oxygen atom and thereby obtained by the chain of the bonding unit of (A) is crosslinked by the bonding unit of (B). It is preferable that the ratio of the total number of binding units of (A) to the total number of binding units of (B) is in the range of 1: 1 to 10: 1. The number average molecular weight of polymetallocarbosilane is preferably 400 to 50,000.

This polymetallocarbosilane is chemically inert and
A plastic film is formed in the middle temperature range of 0 to 500 ℃,
Almost no attack even in corrosive gas atmosphere. 50 more
In the high temperature range of 0 ° C. or higher, since it is gradually converted to ceramic and 80% or more of the original weight remains, a dense ceramic coating can be formed.

A silicone resin is used together to improve the adhesion of the polymetallocarbosilane to the thermal spray coating. As the silicone resin, any of silicone oil, silicone varnish and silicone rubber can be used. The silicone resin content is 1 per 100 parts by weight of polymetallocarbosilane.
0 to 200 parts by weight.

Further, polymetallocarbosilane is used together with an inorganic filler in order to improve the sealing effect of the thermal spray coating. Specific examples of the inorganic filler include B, Mg, Al, Si, Ca, Ti, V,
Cr, Mn, Zn, Zr, Mo, Cd, Sn, Sb, Ba, W, Pb, Bi and other oxides, carbides, nitrides, silicides, borides; Li,
Examples thereof include borates, phosphates and silicates of K, Mg, Ca, Zn and the like. The amount of the inorganic filler compounded is 10 to 200 parts by weight per 100 parts by weight of polymetallocarbosilane.

There is no particular limitation on the method of coating and / or impregnating the sprayed coating with polymetallocarbosilane or a blend of polymetallocarbosilane with a silicone resin or an inorganic filler (hereinafter simply referred to as a blend). A method known per se can be adopted.

(1) A method in which a polymetallocarbosilane or a compound is dissolved or dispersed in an organic solvent, and the solution or dispersion is applied to the thermal spray coating by brushing or doctor blade.

(2) A method of spray-coating the above-mentioned solution or dispersion on a thermal spray coating.

(3) A method of dipping a thermal spray coating in the above solution or dispersion.

The coating and / or impregnation amount of the polymetallocarbosilane or the compound on the thermal spray coating cannot be uniformly defined depending on the properties of the thermal spray coating, but is usually 0.00 per 1 cm ^{2 of} the thermal spray coating.
It is 5-2g.

The organic solvent used in the method (1), (2) or (3) is not particularly limited, but an aromatic hydrocarbon solvent such as toluene or xylene is usually used.

By coating and / or impregnating the sprayed coating with the polymetallocarbosilane or the compound by the method of (1), (2) or (3), and then drying to remove the organic solvent,
Capable of sealing the sprayed coating.

(Effects of the Invention) By the method for sealing a sprayed coating of the present invention, a sprayed coating having excellent heat resistance and corrosion resistance can be formed.

(Example) Reference example Anhydrous xylene and 400 g of sodium were heated to the boiling point of xylene in a nitrogen gas stream, and dimethyldichlorosilane 1 was added dropwise for 1 hour. After completion of the dropping, the mixture was heated under reflux for 10 hours to form a precipitate. The precipitate is filtered, methanol,
Then, wash with water to obtain white powder of polydimethylsilane 42
I got 0g.

On the other hand, 759 g of diphenyldichlorosilane and 124 g of boric acid were heated in a nitrogen gas atmosphere in n-butyl ether at a temperature of 100 to 120 ° C., and the produced white resinous material was heated to 400 ° C. in a vacuum.
530 g of polyborodiphenyl siloxane were obtained by heating for 1 hour.

Next, 0.2 g of the above polyborodiphenylsiloxane was added to 400 g of the above polydimethylsilane and mixed, and heated to 350 ° C. under a nitrogen stream in a second quartz tube equipped with a reflux tube,
Polymerization was carried out for 3 hours to obtain an organic silicon polymer.

400 g of this organosilicon polymer and 200 g of titanium tetraisopropoxide were reacted with xylene 4 as a reaction solvent in a nitrogen gas atmosphere while stirring at 130 ° C. for 1 hour. After xylene was distilled off, the reaction was further performed at 300 ° C. for 10 hours to obtain an organometallic crosslinked polymer containing silicon and titanium. Its number average molecular weight was 1165 as measured by vapor pressure osmosis.

In the polymer obtained here from gel permeation chromatograph and infrared absorption spectrum, the Si-H bond in the organosilicon polymer partially disappears, and the silicon atom in this portion is
The titanium atom of titanium tetraisopropoxide is bonded to the titanium atom through an oxygen atom, whereby a part of the organosilicon polymer has a —O—Ti (OC ₃ H ₇ ) ₃ group in the side chain, and a part of the part. The organosilicon polymer was polytitanocarbosilane crosslinked with Ti-O bonds. The total number of Si-CH ₂ bond units of the total number pair -Ti-O-bond units of the polymer 6: was confirmed to be 1.

Example 1 100 g of polytitanocarbosilane obtained in Reference Example, 20 g of silicon varnish (TSR-116 manufactured by Toshiba Silicon Co., Ltd.) and 100 g of aluminum oxide powder were dissolved and dispersed in 100 g of xylene.

The melt dispersion was spray-coated on a plasma spray coating of aluminum oxide (base material: SS41) having an average coating thickness of 100 μm, followed by drying and sealing treatment. The coating weight of polytitanocarbosilane and the formulation on the thermal spray coating was 0.1 g / cm ² .

This treated thermal spray material is placed in an air oven at 800 ° C for 24 hours.
The sample, which had been left for a period of time and then taken out and allowed to cool in air at room temperature, had no peeling of the thermal spray coating due to oxidation of the base material, and its appearance was almost unchanged.

Comparative Example 1 When a polyvinyl butyral resin-based sealing material was applied to an aluminum oxide coating similar to that described above and then dried and subjected to a sealing treatment, the same heat resistance test as above was performed. Almost completely peeled off, and almost no sealing material remained.

Example 2 A sample obtained by spraying a cast iron base material with NiCr as an undercoat material and a Cr ₃ C ₂ type material as a topcoat material with a total film thickness of 300 μm was spray-coated with the melt dispersion described in Example 1, and dried. A sealing treatment was applied. The coating weight of polytitanocarbosilane and the formulation on the thermal spray coating was 0.1 g / cm ² .

This treated thermal spray material is placed in an air oven at 1000 ° C for 48 hours.
The sample, which had been left for a certain period of time and then taken out at room temperature in the atmosphere, did not peel off the sprayed coating due to the oxidation of the base material, and the appearance was almost unchanged.

Comparative Example 2 When the same thermal resistance test as described above was performed on the sprayed material obtained by applying the two-component epoxy resin to the sample used in Example 2 and then drying and sealing treatment, the sprayed coating was partially formed. Peeling occurred and significant discoloration was observed.

Claims (1)

[Claims] 1. A sprayed coating is coated and / or impregnated with a composition in which 100 parts by weight of polymetallocarbosilane, 10 to 200 parts by weight of a silicone resin and 10 to 200 parts by weight of an inorganic filler are dissolved or dispersed in an organic solvent. A method for sealing a sprayed coating, which is characterized in that