JPS63297469A - Sialon based heat-resistant coating - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant coating, capable of firing and baking in air, having a high heat-resistant temperature in air and high anticorrosive effects on molten metal, by dispersing or dissolving sialon powder with polycarbosilane and silicon polymer in an organic solvent. CONSTITUTION:The aimed coating obtained by dispersing or dissolving (A) sialon powder of a phase consisting essentially of beta-sialon powder expressed by the formula (z is 0-4.2) prepared by preferably mixing (i) amorphous silicon nitride powder with (ii) an oxygen-containing compound of silicon or aluminum and (iii) metallic aluminum, aluminum nitride or silicon so as to provide a desired beta-sialon composition and heating the resultant mixture at 1,300-1,800 deg.C in a nitrogen-containing atmosphere and (B) a polycarbosilane and/or silicone polymer in (C) an organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel heat-resistant paint containing Sialon powder, and more particularly to a novel heat-resistant paint containing Sialon powder, polycarbosilane and/or silicone resin. Regarding paint.

(Prior Art and its Problems) Paints containing polyorganosiloxane as a vehicle and various pigments added thereto are known as heat-resistant paints for preventing corrosion and deterioration of metal and non-metal substrates at high temperatures. This polyorganosiloxane paint has excellent heat resistance when compared with conventionally known organic polymer paints such as polyester and polyimide, but the paint film will still fail in an air atmosphere at a high temperature of over 400°C. Peel off from the base material.

Furthermore, with the development of industry, the furnace body and surrounding parts of aircraft parts, iron and metal smelting furnaces, etc.
There is an increasing demand for coating materials that can prevent oxidation and corrosion of metal or non-metallic substrates exposed to high temperatures exceeding .

Japanese Patent Publication No. 59-12746 discloses that after coating a metal material with polycarbosilane containing a small amount of metal elements and having carbon and silicon as skeleton components, the polycarbosilane is heated to 800-2
A method for producing a heat-resistant metal material is described in which polycarbosilane is converted into silicon carbide by heating and firing at 000°C. Japanese Patent Application Laid-open No. 55-84370 discloses that a coating composition prepared by adding ceramic or metal powder to a semi-inorganic compound containing polysilane is applied to a metal or non-metallic material, and then heated for 400 minutes in a non-oxidizing atmosphere. ~200
A method for obtaining a heat-resistant coating film by heating to 0'C and baking is described.

However, the temperature of this polycarbosilane at 1000℃ (in air)
Since the residual rate after firing is about 30% (in terms of weight), large volumetric shrinkage occurs due to thermal decomposition of polycarbosilane during heating baking. For this reason, the adhesion of the coating film to the substrate becomes insufficient in the case of baking. When baking is performed in an oxidizing atmosphere such as in the air, most of the coating film peels off from the base material. The heat resistance of the resulting coating film is approximately 40% in air.
0°C, which is not much different from the heat resistance temperature of conventional polyorganosiloxane paints.

In addition, the present applicant has a high firing survival rate in air, and can be fired in air.Furthermore, it has a high heat resistance temperature in air, and can be used for metal or nonmetal substrates under high temperature conditions. Patent application 1986-1 as a paint with high oxidation and corrosion prevention ability
No. 93786 and Japanese Patent Application No. 61-76706 disclose new types of heat-resistant paints.

(Object of the invention) The object of the present invention is to enable baking in air,
Furthermore, the present invention provides a heat-resistant paint that has a high temperature resistance in air and has a high ability to prevent oxidation and corrosion of metal or non-metallic base materials under high-temperature conditions, particularly a heat-resistant paint that is highly effective in preventing corrosion of molten metal.

(Means for Solving the Problems) The present invention provides that Sialon powder contains polycarbosilane and/or
Alternatively, the present invention relates to a heat-resistant paint characterized by being dispersed or dissolved in an organic solvent together with a silicone resin.

The sialon powder in the present invention is a powder in which the primary particles of the powder itself are α-sialon or β-sialon, and both are obtained by crystallizing amorphous silicon nitride powder as a part of the raw material. It is something that was given.

In other words, the α-sialon powder contains the following substances (
a), (b), (c), or substance (a), (g)),
Using (c) and (d) as raw materials, (a) amorphous silicon nitride powder, (a) metallic aluminum or aluminum nitride, (c)
Metal oxides that form an interstitial solid solution between the lattices of α-Sialon or metal salts that produce oxides of these metals by thermal decomposition (d) Oxygen-containing compounds of aluminum or silicon Formula MX
(S t, kl) + □ (0, N) + 6 (wherein, M is a metal that forms an interstitial solid solution, and X is a number greater than 0 and less than or equal to 2). After adjusting and mixing the ratio of each raw material so that it has an α-sialon composition,
The mixture was heated at 1300-1800°C in a nitrogen-containing gas atmosphere.
An α-sialon powder having the above composition as a main phase, which has been crystallized by heating to a temperature in the range of , is used.

In addition, the β-sialon powder includes (a) amorphous silicon nitride powder, (b) an oxygen-containing compound of silicon or aluminum, and (c) metallic aluminum, aluminum nitride, or silicon in a desired β-sialon composition. and heating the mixture to a temperature in the range of 1300-1800<0>C under a nitrogen-containing atmosphere.

(In the formula, Z is a number greater than O and less than or equal to 4°2.) A powder having β-sialon as a main phase is used.

As the polycarbosilane in the present invention, the below-mentioned (A
) a carbosilane bonding unit and at least one type of (B) metalloxane bonding unit described below, (However, R8 and R2 may be the same or different,
Each independently represents a lower alkyl group, a phenol group, or a hydrogen atom. ) (B): -←M-0→- (However, M represents at least one element selected from the group consisting of Ti, Zr, Mo, and Cr, and in some cases at least a portion of each of the above elements has at least one lower alkoxy group or phenoxy group as a side chain.

) A polymer in which each bonding unit of (A) and (B) is randomly bonded in the main chain skeleton, and/or at least a portion of the silicon atoms of the bonding unit of (A) is the bonding unit of (B). are bonded to each of the metal elements through oxygen atoms, whereby the polycarbosilane moiety obtained by the chaining of the bonding units of (A) is formed by the bonding units of (B),
It is a polymer crosslinked via oxygen, the ratio of the total number of bonding units of the above (A) to the total number of bonding units of the above (B) is in the range of 1:1 to 10:1, and the number average molecular weight is 400 to 50,000, and/or mainly consists of the following (A) carbosilane bond units and the following (B) silane bond units (provided that R, R
, R□, Ra, Rs and R6 may be the same or different and each independently represents a lower alkyl group, an allyl group, a phenyl group, a silyl group or a hydrogen atom. ) An organometallic polymer in which the ratio of the total number of bonding units of the above (A) to the total number of bonding units of the above (B) is in the range of 20:1 to 1:20, and the number average molecular weight is 400 to 50,000. is used.

As the silicone resin in the present invention, polyorganosiloxane, silicone oil, silicone oil, silicone rubber, etc. are used.

As the above-mentioned coating film forming component, it is preferable to use polycarbosilane alone or a mixture of polycarbosilane and a silicone resin.

The heat-resistant paint of the present invention is obtained by dispersing or dissolving Sialon powder, polycarbosilane and/or silicone resin in an organic solvent.

Benzene, toluene, xylene, etc. are used as the organic solvent.

The ratio of Sialon powder to polycarbosilane and/or silicone resin varies depending on the application, but if polycarbosilane and silicone resin are used at the same time with respect to 100 parts by weight of Sialon powder, the ratio of both can be arbitrary. , a total of 20 to 2000 parts by weight, especially 50 to 100 parts by weight.
0 parts by weight is preferable, and when polycarbosilane or silicone resin is used alone, it is preferably 10 to 1 part by weight.
000 parts by weight, especially 50 to 700 parts by weight. If the amount of polycarbosilane and/or silicone resin relative to the Sialon powder is less than the above range, the flexibility of the baked coating will be lost, and if it is greater, the adhesion between the coating and the substrate will be lost. This is not preferable because the corrosion resistance against molten metal also decreases.

Further, in the present invention, a small amount of colored inorganic compound powder may be added in order to adjust the color tone of the coating film.

When using the heat-resistant paint of the present invention, the heat-resistant paint can be applied to a metal substrate or a non-metallic substrate such as glass or ceramic firebrick by brushing, using a roll coater, a spray gun, or the like.
After applying by dipping or other methods, dry baking is performed.

A coating amount of 20 to 100 g/rd is generally desirable.

If the coating amount is less than 20 g/nt, pinholes will occur and corrosion resistance will decrease. On the other hand, if the amount is more than 100 g/rrf, cracks in the coating film tend to occur during baking, which is not preferable.

The baking temperature is preferably 150° C. or higher, but if the object to be coated is placed in a usage environment of 150° C. or higher after painting, there is no need to provide a baking step. If the baking temperature is lower than 150°C, the strength of the coating film will be low, and both hardness and impact resistance will be poor, which is not preferable.

Since the heat-resistant paint of the present invention contains polycarbosilane and/or silicone resin, when it is baked onto the surface of the base material, ultrafine silicon carbide or oxide particles are generated, creating a gap between the paint film and the base material. form a strong bond. therefore,
Forms a dense protective film layer that does not peel off even in air at temperatures of 1000°C or higher. Furthermore, Sialon powder bonds the coating film and the base material more firmly, creating a coating film with excellent heat resistance and flexibility. In particular, Sialon powder itself is a structural ceramic powder with excellent oxidation resistance and corrosion resistance against molten metal.
The heat-resistant paint of the present invention also has a high anticorrosion effect on molten metal.

(Example) This will be explained in more detail below with reference to Examples.

In addition, in the reference examples and examples, % and parts indicate weight % and parts by weight unless otherwise specified.

Reference Example 1 Anhydrous xylene was added to a three-way flask for 5 days. ! M! and 400 g of sodium were added thereto, heated to the boiling point of xylene under a nitrogen gas stream, and dimethyldichlorosilane 11 was added dropwise over 1 hour. After the dropwise addition was completed, the mixture was heated under reflux for 10 hours to form a precipitate. This precipitate was filtered and washed first with methanol and then with water to obtain a white powder of polydimethylsilane 4.
20g was obtained.

400 g of the above polydimethylsilane was charged into a 31-meter three-lough flask equipped with a gas inlet tube, a stirrer, a condenser, and a distillation tube, and the mixture was placed under a nitrogen stream (50-rall l flask) with stirring.
1 inch) and heat-treated at 420° C. to obtain 350 g of a colorless and transparent slightly viscous liquid in the distillation vessel. The number average molecular weight of this liquid is determined by vapor pressure osmosis method (VPO method)
It was measured to be 470.

In addition, by measuring the far-infrared absorption of this material, we found that mainly -4S i CHz + - bond units and (Si-3i
It was confirmed that it is an organic silicon polymer consisting of +-bond units and having a hydrogen atom and a methyl group in the silicon side chain.

Reference Example 2 Next, 40 g of this organosilicon polymer and 20 g of titanium tetraisopropoxide were weighed out, and 40 g of xylene was added to the mixture.
00 relative was added to form a mixed solution consisting of a homogeneous phase, and a reflux reaction was carried out under a nitrogen gas atmosphere at 130° C. with stirring for 1 hour. After the reflux reaction was completed, the temperature was further raised to distill off the solvent xylene, and then polymerization was carried out at 1.300° C. for 10 hours to obtain an organometallic crosslinked polymer containing silicon and titanium. The number average molecular weight of this polymer was determined to be 1165 by the vPo method.

In addition, gel permeation chromatography and infrared absorption spectra revealed that the 5i-H bonds in the organosilicon polymer have partially disappeared in the polymer obtained here, and the silicon atoms in this part are It is bonded via a titanium atom and an oxygen atom, so that some of the organosilicon polymers have -OTi (OC3H?) groups in their side chains,
A part of the organosilicon polymer is polytitanocarbosilane crosslinked with 1+Ti-0+- bonds, and the reaction rate and/or crosslinking rate at the 5i-H bond portion in this polymer is 44.5%. be. -GSi-CH2 bonding units and one+5i of the organosilicon polymer portion of this polymer
-3i+- total number of bonding units vs. -0-Ti (QC3H7)
It was confirmed that the ratio of the total number of 3 and 1+T i -0+- binding units was approximately 681.

The above reaction product is dissolved in xylene so that the solid content is 50%.
A solution of

Reference Example 3 127.6 parts of amorphous silicon nitride powder obtained by heat treating silicon diimide at 1200°C, 38.8 parts of T-alumina (specific surface area: 100 M/g) and metal aluminum powder (specific surface area: 0) .3rrf/g) were mixed for 1 hour in a vibration mill under a nitrogen gas atmosphere. This mixed powder was filled into a carbon crucible, set in a high frequency induction furnace, and heated from room temperature to 1200°C for 1 hour under a nitrogen gas atmosphere.
Crystallization was carried out by heating from 1200° C. to 1400° C. for 4 hours and then from 1400° C. to 1600″C for 2 hours.

When the obtained powder was examined, the size of the -order particles was 0.
The particle size was uniformly 3 to 0.6 μm, and it was confirmed by X-ray diffraction that it was β-sialon. The analytical values for each element are as follows: Product composition (wt%) St A/! ON 38.9 18.7 12.1 30.3 It can be seen that the desired β-sialon powder was obtained. In addition, the impurity iron is 180pp+o, and the calcium is 200p.
It was pm.

Reference example 4 Amorphous silicon nitride powder 479, the same as that used in reference example 3
．． 2 parts of YzO's powder, 59.4 parts of YzO's powder, and 63 parts of metal Al powder were mixed for 1 hour in a vibration mill under a nitrogen gas atmosphere. This mixed powder was filled into a carbon crucible, set in a resistance heating type high temperature furnace, and heated from room temperature to
Crystallization was performed by heating to 200° C. for 1 hour, from 1200° C. to 1400° C. for 4 hours, and then from 1400° C. to 1600° C. for 2 hours.

The obtained powder was a Y-based α-sialon powder with the characteristics shown below.

Characteristic theoretical composition of α-sialon powder Y o, s S i q, ys A l□
, 2,0°, 75N + 5.2 parts Specific surface area 2.5 bo/g Grain shape Equiaxed crystal formation Phase α phase 90% or more Product composition (wt%) YSi A/! ON 7.2 44.2 9°8 4,9 33.9 Excess oxygen amount 2.9% by weight Example 1 Pheasant 1 Fus of polytitanocarbosilane of Reference Example 2 50
% xylene solution (TSR-1 16 manufactured by Toshiba Silicon Corporation)
A heat-resistant paint was obtained by mixing 30 parts of the β-sialon powder and 40 parts of the β-sialon powder of Reference Example 3.

This paint was applied to a stainless steel plate (SUS304) with a bar coater to a thickness of about 50 μm, and then heated to 200°C.
I baked it open for an hour.

This baking-coated steel plate was heated in an oven at 1000° C. for 96 hours, then taken out from the oven and coated in air.

In order to evaluate the adhesion of this coating film to the base material, 2 m
Using a cutter knife, make 11 vertical and 11 horizontal cuts into the base material with a width of m, making a total of 100 goban stitches.
Adhesive cellophane tape was attached to the surface, and the number of coatings remaining in the rows after the tape was rapidly peeled off was examined, and it was found to be 96/100, showing very good adhesion.

Example 2 The β-sialon powder in Example 1 was replaced with the α-sialon powder in Reference Example 4.
A heat-resistant paint was obtained in the same manner as in Example 1, except that Sialon powder was used.

This paint was applied to a thickness of about 50 μm on a stainless steel plate (SUS304) with a bar coater, and then heated to 200°C.
Bake it in the oven for 1 hour.

This baking-coated steel plate was heated in an oven at 1000° C. for 96 hours, then taken out from the oven and coated in air.

When the adhesion of this coating film to the base material was evaluated in the same manner as in Example 1, the number of remaining coating films in the rows was 9.5
/100, which showed very good adhesion.

Example 3 100 parts of the β-sialon powder of Reference Example 3 and 100 parts of the polytitanocarbosilane xylene solution of Reference Example 2 were uniformly mixed in a ball mill. This was brushed onto an iron plate to a thickness of 100 μm, dried at room temperature, placed in an oven at 300° C., baked for 30 minutes, and immediately cooled to room temperature. Next, this coated steel plate is immersed in a pure aluminum melt at 600°C for 10 minutes, and then pulled out to check the corrosion resistance and wettability of the coating film against the aluminum melt (the aluminum melt adheres to the surface of the coating film when it is pulled up). was examined, but no cracks, peeling, or wetting was observed.

Patent applicant: Ube Industries Co., Ltd. Procedural amendment (voluntary) July Qday, 1986

Claims (7)

[Claims] (1) A heat-resistant paint characterized in that Sialon powder is dispersed or dissolved in an organic solvent together with polycarbosilane and/or silicone resin. (2) Sialon powder contains (a) amorphous silicon nitride powder, (b) an oxygen-containing compound of silicon or aluminum, and (c) metallic aluminum, aluminum nitride, or silicon in a desired β-sialon composition. and heating the mixture to a temperature in the range of 1300-1800°C under a nitrogen-containing atmosphere, with the formula Si_b_-_zAl_zO_zN_s_-_z, where z is a number greater than 0 and less than or equal to 4.2. The heat-resistant paint according to claim 1, which is a powder containing β-sialon as a main phase. (3) Sialon powder contains the following substances (a), (b),
(c) or substances (a), (b), (c) and (d)
As a raw material, (a) amorphous silicon nitride powder, (b) metallic aluminum or aluminum nitride, (c) interstitial solid solution of metal oxides or thermal decomposition between α-sialon lattices. Metal salts that produce oxides (d) Oxygen-containing compound of aluminum or silicon Formula Mx (Si, Al)_1_2 (O, N)_1_6 (wherein M is a metal that forms an interstitial solid solution, x is a number greater than 0 and less than or equal to 2.)
- After adjusting and mixing the ratio of each raw material so that it has a sialon composition, the mixture is heated to 1300 ml in a nitrogen-containing gas atmosphere.
The heat-resistant paint according to claim 1, characterized in that it is α-sialon powder having the above composition as a main phase, which has been crystallized by heating to a temperature in the range of 1800°C to 1800°C. (4) Polycarbosilane is composed of (A) carbosilane bonding units described below and at least one type of (B) metalloxane bonding units described below, (A): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1 and R_2 may be the same or different and independently represent a lower alkyl group, a phenol group, or a hydrogen atom.) (B): -(M-O)- (However, M is selected from Ti, Zr, Mo, and Cr. (A) and (B) above (A) and (B). A polymer in which each bonding unit is randomly bonded in the main chain skeleton, and/or at least a portion of the silicon atoms in the bonding unit (A) are bonded to each metal element and oxygen atom in the bonding unit (B). The polycarbosilane moiety obtained by the chaining of the bonding units of (A) is bonded through the bonding units of (B),
It is a polymer crosslinked via oxygen, the ratio of the total number of bonding units of the above (A) to the total number of bonding units of the above (B) is in the range of 1:1 to 10:1, and the number average molecular weight is 400 to 50,000, the heat-resistant paint according to claim 1. (5) Polycarbosilane mainly consists of the following (A) carbosilane bond units and the following (B) silane bond units, (A): ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B): ▲ Mathematical formulas, There are chemical formulas, tables, etc. ▼ (However, R_1, R_2, R_3, R_4, R_5 and R_6 may be the same or different and each independently represent a lower alkyl group, allyl group, phenyl group, silyl group or hydrogen atom. .) The ratio of the total number of bonding units of the above (A) to the total number of bonding units of the above (B) is in the range of 20:1 to 1:20, and the number average molecular weight is 400 to 50,000. A heat-resistant paint according to claim 1. (6) The heat-resistant paint according to claim 1, wherein the silicone resin is selected from the group consisting of polyorganosiloxane, silicone oil, silicone varnish, and silicone rubber. (7) Heat resistance according to claim 1, characterized in that the polycarbosilane is 10 to 1000 parts by weight and/or the silicone resin is 10 to 1000 parts by weight based on 100 parts by weight of the sialon powder. paint.