JPS5953555A - Oxidation preventing paint composition - Google Patents

Abstract

PURPOSE:To provide the titled composition for graphite-based refractory material, having excellent storage stability and applicability and resistant to the breakage of the coating film, by mixing a binder composed of an alkali silicate, borax and a lead silicate compound, with an amphoteric metal oxide, etc. such as cobalt oxide, alumina, etc. CONSTITUTION:The objective composition can be prepared, e.g. by mixing (A) a binder obtained by mixing (i) 100pts.wt. of a mixture of an alkali silicate and borax at a weight ratio of 100:(30-60) with (ii) 6-90pts.wt. of a lead silicate compound having a PbO/SiO2 ratio of (60-93):(40-7) by weight, with (B) an amphoteric metal oxide such as cobalt oxide, alumina, etc., and if necessary, adding (C) a filler, an additive, etc. to the mixture. EFFECT:The composition has excellent antifoaming property and gives a pinhole- free uniform coating film having excellent moisture resistance and durability and sufficiently high oxidation preventing effect.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides fB1m, which prevents oxidation of refractories against high heat by coating them on refractories, especially graphite refractories.
The present invention relates to a composition.

Conventionally, graphite-based refractories have been widely used in continuous casting methods for steelmaking due to their spalling resistance and corrosion resistance. It has the drawback that it becomes rIlp and deteriorates, causing problems with the refractory's intended function. Therefore, various 1→ρ conversion prevention materials have been proposed for the purpose of preventing oxidation of graphite-based refractories, but one of the most widely used is a silica-based alkali-porous sand composition. be.

However, the temperature range at which graphite-based refractories oxidize is approximately 500°.
C to 900°C, and among these, the ones that are most acidic are:
Although the melting point is 600°C to 800°C, the melting point of the alkali silicate-borax composition is 750°C or higher, so the antioxidant effect is not actually sufficient. In addition, in alkali silicate-borax compositions, an alkaline substance (such as NaO) is added to improve the stability of the composition.
tf, K OH nato) wo% jjk +.

The water resistance, moisture resistance, and durability are significantly inferior.
Therefore, the coating film of the silicified alkaline borax-based composition is not maintained for a long period of time, causing coating defects such as washing away or chipping, which reduces the silicified mountain protection effect.

The present inventors have carried out intensive research on 4Ur in order to overcome the drawbacks described below, and have completed the present invention as a result.

In the present invention, cobalt oxide and an amphoteric metal oxide such as alumina are mixed with alkali silicate, borax, and a silica Y't5 LK'f compound proboscis, and cobalt oxide and an amphoteric metal oxide such as alumina are mixed with this. A filler that is essential for forming a good quality.
It is characterized in that it contains additives and is coated with st'J. The configuration of the present invention will be explained below with reference to FIG. 11. .

Among the components of the present invention, the first purpose of the lead silicate compound, which plays the most important role as one of the bonds 11, is that the melting point of the amniotic fluid alkali silicate-borax composition is 750°
C or higher, 61J (effectively lowers the score. In the present invention, P l) 0/
A lead silicate compound having a weight ratio of Si 02 (7) of 60 to 93:4 to 7 is used. Key in the above range
The lead compound produces significantly less lead oxide fume during tgIIl/I!, which is the case with other lead compounds, and not only has less loss of 111 of the heavy lead component, but it is also environmentally safe. In the present invention, the weight [,1
The mixture containing the following ratio is dissolved and cooled.
11.
6 to 90 parts per 100% ijt of the amalgamated mixture
Parts by weight preferably, mixed with 1 part of 15-30-rlj.

Pl+0:S+02=(50~93:4
Is it a compound of 0 to 7?
When the alkaline powder is 6 parts or less per 1°0 parts of the material, the drop in the point is not 5.10, and no effect on stopping 19'i of liquefaction can be expected. - Manmon) 0:s
If the lead silicate compound with 2=60-9B:40-7 exceeds 90 parts of silicic acid alkali-porous sand described in 1. [1] Excessive fluidity occurs in the component, and the coating is washed away from the surface of the refractory, so the oxidation prevention role 1 is lost. Present invention (7) P t+ O: S r 02 = 60-9
The second purpose of combining lead silicate compounds with a ratio of 3:40 to 7 is as follows. A composition containing a lead silicate compound with T'l+O:5i02 =60-93:40-7 is a composition containing a large amount of an alkaline substance (for example, Na01 (, KOI (etc.)) can be significantly reduced. Based on the structure of the present invention, lead silicate compounds within the specified combination range can be mixed into alkaline borax silicate = 100: 80 to 6.
When 6 to 90 parts by weight are added to 100 parts by weight of a mixture that gives a
Despite the addition of small amounts of NaOi4, KOH, etc.), the storage stability is good at around 4α, and there is no increase in viscosity, separation,
It does not cause gelation at all and can be used at normal ambient temperatures (1.
Maintains low viscosity (1000°C to 40°C)
cps ~ 300 CICIIS), so the workability during coating is extremely good. In addition, the composition according to the present invention has significantly improved ttL resistance and durability for +1'A coating compared to conventional alkali silicate-borax compositions, so it can be used for a long period of time after film formation. It shows little deterioration when left unattended, and maintains a stable state over a long period of time without peeling off the film like conventional alkali silicate-porous sand compositions, and maintains its antioxidant effect at all times. You can expect it.

PbO of the present invention: S 1o2 = 6Q ~ 93: 40
〜7 lead silicate compound with silica alkaline borax =
The third purpose of the composition, which is blended in an amount of 6 to 90 parts by weight to 100 parts by weight of a mixture of 100:80 to 60 parts by weight, is as follows. Conventional alkali silicate-borax-based compositions generate bubbles from within the film when exposed to high heat, but because the film lacks the necessary and sufficient fluidity, pinholes are formed and the film deteriorates. It becomes a defect. On the other hand, based on the structure of the present invention, a lead silicate compound is mixed at a weight ratio of 6 to 90 parts by weight with respect to 100 parts by weight of the mixture such that the alkali silicate diborax = to o: 3 to 60. Preferably, 15 to 30 parts by weight of an amphoteric metal oxide (for example, Al2O8, F
By mixing 620 g (!: ),
It has antifoaming properties that are not found in conventional alkali silicate-borax compositions, and quickly eliminates bubbles that tend to occur in the film when exposed to high heat, eliminating pinholes and providing a uniform coating over the entire surface. 1. The structure of the present invention will be shown below with reference to Examples and Comparative Examples, which will help you understand the excellent effects of the present invention.

The spacing method below is as follows.

A. Property test of the composition (1) Coating workability Determining the coating workability at each temperature (2) Storage stability The stability of the 13° film was visually determined by leaving it sealed in a room at 20°C and 160% RIF for 3 months. Performance Test Each composition was applied to a graphite-based refractory base material to a thickness of 500 mp and dried at 80'C for 4 hours to form a film, which was used as a test specimen.

(1) Durability of Coating The test specimen was left standing in a constant temperature and humidity chamber at 20° C. 180% R1-T for two months, and then the coating surface was observed to visually determine the durability.

(2) Anti-oxidation properties of the coating Based on the temperature curve shown in the attached drawing, the film was stored in a gas furnace (I = P (3 slag) for 4 hours at an increasing internal temperature, then taken out and rapidly cooled to room temperature. Visually judge the degree of oxidation of the base material.

*, Pl) 0:5i02=85:1’5 result Judgment: ◎Excellent, ○Excellent, △Problems, ×Not possible

[Brief explanation of drawings]

The figure shows the temperature change inside the slag furnace in which the anti-oxidation test was conducted. 477-

Claims (1)

[Claims] l. 11J such as cobalt oxide and alumina to a binder consisting of alkali silicate, borax, and lead silicate compound.
An oxidation-preventing coating composition characterized in that it is prepared by mixing a d-type metal oxide and firstly adding fillers, additives, etc. necessary for forming a coating to form a coating of 4:9↓. thing. The antioxidant coating composition according to claim 1, characterized in that in the 26 silicic acid compound, the weight ratio of J) bO/5i02 is defined in the range of 60 to 93:40 to 7.