RU2244693C2 - Glass for steel pipe enameling - Google Patents

Abstract

FIELD: glass-enamel protective covering composition for low-carbon and medium-carbon steel.

SUBSTANCE: claimed composition contains (mass %): SiO₂ 45.0-49.0; Al₂O₃ 1.5-4.5; CoO 0.5-0.9; CaO 6.0-9.5; ZnO 2.0-4.0; MgO 3.0-6.0; Fe₂O₃ 0.1-0.9; B₂O₃ 10.6-14.0. Composition is useful for metallurgic and oil industry, in particular for pipe lines maintaining in active media, as well as for water-supply systems. Glass of present invention affords the ability to sufficiently increase durability of steel pipes in aggressive media, and as a result to reduce metal consumption, decrease equipment downtime, safe purity of transported products, etc.

EFFECT: glass-enamel of simplified composition without quality deterioration.

2 tbl, 21 ex

Description

The invention relates to compositions of glass-enamel protective coatings for low-carbon and medium-carbon steels and can be used in the metallurgical and petroleum industries, where pipeline transport is used, operating in active environments, as well as in the water supply system.

Known enamel coating for steel (AS No. 988785, dated 12.06.81, IPC С 03 С 7/04, publ. 15.01.83, Bull. No. 2), including SiO ₂ , Al ₂ O ₃ , Na ₂ O , K ₂ O, Li ₂ O, B ₂ O ₃ , MnO ₂ , Co ₂ O ₃ , F, oxygen compound of nickel. The glass additionally contains TiO ₂ , SnO, Cr ₂ O ₃ , and as an oxygen compound of Nickel contains NiO in the following ratio of components, wt.%:

SiO ₂ - 38.0-40.0
Al ₂ O ₃ - 1.5-1.9
Na ₂ O - 15.5-18.0
K ₂ O - 2.0-3.3 Li ₂ O - 3.6-4.5
In ₂ O ₃ - 8.0-12.0
MnO ₂ - 3.5-5.2
Co ₂ O ₃ - 0.9-1.2 F - 3.7-4.5
Ni - 0.7-0.9
TiO ₂ - 5.0-8.3
SnO - 5.8-6.8 Cr ₂ O ₃ - 2.3-3.2

Also known is glass granulate for applying a glass coating to the inner surface of a steel pipe (patent No. 2109702 from 02.24.95, IPC C 03 C 27/02, publ. 04/27/98, Bull. No. 12), containing, wt.%:

SiO ₂ - 53.0
Al ₂ O ₃ - 3.0
CaF ₂ - 5.0
K ₂ O - 8.0 Na ₂ O - 12.0
TiO ₂ - 2.0
Co ₂ O ₃ - 0.5
NiO - 0.5 SrO - 5.0
Bao - 10.0
Cr ₂ O ₃ - 0.5
impurities 0.5

The disadvantage of these compositions is the complexity of their chemical composition, respectively, their high cost.

The closest composition is a glass-enamel coating for steel (AS No. 16006478 dated 9.03.88 g, IPC C 03 C 8/06, publ. 15.11.90, Bull. No. 42), containing, wt.%:

SiO ₂ - 45.9-33.3
In ₂ O ₃ - 25.4-18.0
Na ₂ O - 23.1-16.1
FeO - 8.4-2.6 MnO - 6.4-2.3
MgO - 5.0-2.5
Li ₂ 0 - 2.5-2.0
Na ₃ AlF ₆ - 3.0-3.5 Al ₂ O ₃ - 1.7-1.1
CuO - 1.5-2.7
ZnO - 1.0-2.6

The disadvantage of the prototype is also the complexity of its chemical composition and, accordingly, its high cost.

The objective of the invention is to simplify the composition of glass for vitrification of steel pipes without compromising the quality of the protective coating.

The technical result from the use of the invention is to reduce the cost of vitrification of pipes due to the cheapening of the composition of the glass.

The essence of the invention lies in the fact that glass for the vitrification of steel pipes containing SiO ₂ , Al ₂ O ₃ , MgO, B ₂ O ₃ , Na ₂ O, ZnO, iron oxide, according to the invention additionally contains CaO and CoO in the following ratio of components, wt.%:

SiO ₂ - 45.0-49.0
CaO - 6.0-9.5
Na ₂ O - 19.0-23.5 Al ₂ O ₃ - 1.5-4.5
MgO - 3.0-6.0
CoO - 0.5-0.9 Fe ₂ O ₃ - 0.1-0.9
In ₂ O ₃ - 10.6-14.0
ZnO - 2.0-4.0

This glass composition differs from the prototype in that instead of the 2 components of MnO and FeO (in the prototype), one component is used as a coupling activator — cobalt oxide CoO, which is introduced in a much smaller amount than MnO and FeO, while the adhesion properties of the coating with a steel surface do not deteriorate.

Additionally, calcium oxide (CaO) is introduced into the composition, which lowers the melting temperature and viscosity of the glass, which reduces the cost of preparing the glass. At the same time, CaO improves the thermophysical and chemical properties of glass, such as heat resistance and chemical resistance.

Iron oxide is present in the glass as Fe ₂ O ₃ . If in the prototype iron oxide in the form of FeO is specially introduced to improve the adhesion of glass to steel in an amount of up to 8.4%, then Fe ₂ O ₃ is not specifically introduced into the composition as a component, it is present in the glass as an impurity that is introduced into the composition raw materials in the preparation of glass, such as quartz sand and dolomite. The amount of this impurity is insignificant (not more than 0.9%), therefore, the properties of the protective glass coating do not deteriorate compared to the prototype.

The proposed composition of the glass is optimal, because, despite the simplification, it meets all the requirements for glass-enamel coatings for steel pipes.

So, if the amount of SiO ₂ is less than 45.0%, there is a decrease in glass hardness, insufficient glass resistance to water, reduced alkali resistance and acid resistance.

If the amount of SiO ₂ is more than 49.0%, then there is an increased viscosity of the glass melt, which leads to increased refractoriness, and therefore, complicates its use.

If the amount of Al ₂ O ₃ is less than 1.5%, then the strength and chemical resistance of the glass deteriorates, and if more than 4.5%, the increased content of Al ₂ O ₃ makes melting more difficult, which increases the cost of using glass.

If the amount of CaO is less than 6.0%, then lower glass strength and chemical resistance are observed, and if CaO is more than 9.5%, the tendency of glass to crystallize increases.

If MgO is less than 3.0%, then the glass refractoriness, lower chemical resistance of the glass are observed, and if MgO is more than 6.0%, the melt viscosity of the glass increases, the time of glass penetration, and the glass's resistance to water decreases.

If the amount of B ₂ O ₃ is less than 10.6%, then an increased viscosity of the glass melt, reduced heat resistance and chemical resistance are observed, and if B ₂ O ₃ is more than 14%, the water resistance and alkali resistance deteriorate.

If Na ₂ O is less than 19.0%, then an increased melting temperature and viscosity of the glass are observed, and if more than 23.5%, then a lower chemical stability of the glass and its reduced microhardness are observed.

If CoO is less than 0.5%, then the required adhesion of glass to steel is not observed. An increase in CoO of more than 0.9% is impractical because the required adhesion properties of the glass coating to the steel surface are achieved, and excess CoO will only increase the cost of the glass.

If the amount of ZnO is less than 2.0%, then reduced hardness, glass strength, acid resistance and glass resistance to water are observed, and if ZnO is more than 4.0%, then the alkali resistance of the glass decreases.

Fe ₂ O ₃ in the glass should be no more than 0.9%, since this admixture negatively affects the properties of the glass, especially its mechanical strength. The content of Fe ₂ O ₃ in the glass is limited to not more than 0.9% by using better raw materials that comply with GOST. It is impossible to obtain less than 0.1% Fe ₂ O ₃ in this glass, because it is found in raw materials used in the preparation of glass, such as silica sand and dolomite.

The compliance of the claimed object with the criterion of "Inventive step is proved as follows.

Known composition of enamel (and.with. No. 1265159, dated 09.12.83, IPC С 03 С 8/06, publ. 23.10.86, Bull. No. 39), in which there is a sign similar to the claimed one, namely, the composition enamel includes CaO in an amount of 0.35-2.58 wt.%. However, the known composition of the enamel differs from the claimed. So, it additionally includes Cr ₂ O ₃ , CuO, Fe, which are absent in the claimed object, i.e. known composition is more complex.

Since the inventive glass has a different composition, CaO interacts with other components of the glass. Therefore, in the inventive object, it is present in a different amount, namely 6.0-9.5 wt.%, And it is precisely such an amount that it is necessary that, together with other components, it ensures the strength of the glass and its chemical resistance.

Thus, the known CaO component functions in the inventive facility in a different environment, which led to a change in its quantitative ratio in the inventive composition and the acquisition of the necessary qualities by a glass coating.

There is also a solution (patent No. 2109702 from 24.02.95, IPC C 03 C 27/02, publ. 24.04.98, Bull. No. 12), in which there is also a sign similar to the claimed one, namely, the composition of glass for steel coatings include CoO in an amount of 0.5 wt%.

However, the known composition includes a number of components that are absent in the claimed, namely CaF ₂ , K ₂ O, NiO, SrO, BaO, Cr ₂ O ₃ , TiO ₂ , SnO, i.e. the composition is more complex.

And in the inventive composition, due to a different composition of the incoming components, CoO interacts with a different composition of the components, i.e. It works in a different environment, while the claimed combination of components with a smaller number of them still provides the properties necessary for a glass coating with a steel surface.

An analysis of the above similar features indicates that they are not identical, since the components considered are in a different environment and interact with other components, and the claimed combination of components provides the glass coating with the required properties and quality, which indicates the compliance of the claimed object with the criterion of “inventive step "

Glass for the vitrification of steel pipes is obtained as follows. The following raw materials are used: quartz sand, boric acid, soda ash, zinc oxide, calcium borate, cobalt (II, III) oxide, dolomite. Raw materials are crushed in a dry grinding ball mill to a particle size of not more than 2 mm. All glass components are weighed, poured into a mixer, mixed and fed into a batch-type rotary kiln, where they are fused. The finished molten glass is granulated by pouring into a perforated cube installed in water. After drying and crushing, the glass granules are loaded into steel pipes for vitrification. Vitrification is carried out by heating the granulate in the pipes while rotating and moving them.

Specific examples of glass for the vitrification of steel pipes (compositions are given in table. No. 1).

The properties of the proposed compositions in comparison with the prototype are given in table. No. 2.

The tests are carried out according to standard methods.

The raw materials used in the specific examples are as follows:

1. Quartz sand GOST 7031-75.

2. Boric acid GOST 18707-78.

3. Soda ash GOST 51.00-85E.

4. Zinc oxide GOST 5161-79.

5. Calcium borate GOST 29938-78

6. Cobalt (II, III) oxide GOST 4467-79.

7. Dolomite of local origin STP 0401.14.36-2-80-88.

Example 1. Glass for the vitrification of steel pipes contains, wt.%:

SiO ₂ - 47.0
Al ₂ O ₃ - 3.0
CaO - 7.8 MgO - 4.5
B ₂ O ₃ - 12.3
Na ₂ O - 21.6 CoO - 0.7
ZnO - 3.0
Fe ₂ O ₃ - 0.1

The properties of the above optimal composition: high adhesion, hardness Mohs - 6, alkali resistance - 80 mg · dM ² (II class alkali resistance), water resistance - 0.60 cm ³ · g ^-1 (III hydrolytic class of water resistance) and resistance to abrasion - 1.07 mg / kg of abrasive.

Examples 2-3 differ from example 1 in that the compositions take the boundary ratios of the components that make up the glass.

The properties of these compositions meet the requirements for glass enamel coatings.

Examples 4-5 differ from example 1 in that the composition of the amount of SiO ₂ taken is less than the boundary - 44 wt.% (Example 4) and more than the boundary - 50 (example 5).

At the same time, the properties of the glass deteriorated, namely, in example 4, a decrease in water resistance to 1.45 cm · g ^-1 , alkali resistance to 180 mg · dm ^-2 , and in example 5, an increase in the refractoriness of glass to 950 ° C is observed, which requires an increase temperature in the kiln, which increases costs.

Examples 6-7 differ from example 1 in that in the composition the amount of Al ₂ O _{3 was} taken less than the boundary - 1.0 wt.% (Example 6) and more than the boundary - 5.5 wt.% (Example 7). Moreover, in example 6, the abrasion resistance index decreased to 1.2 mg / kg of abrasive, and in example 7, the glass refractoriness increases to 950 ° C.

Examples 8-9 differ from example 1 in that in the composition the amount of CaO was taken less than the boundary - 5.0 wt.% (Example 8) and more than the boundary - 10.5 wt.% (Example 9). At the same time, the properties of the glass worsened, namely, in example 8, a decrease in alkalinity to 177 mg · dm ^-2 and resistance to abrasive wear to 1.2 mg / kg of abrasive is observed, and in example 9 the glass is more prone to crystallization, which increases the cooling time of glass coating, which reduces the productivity of the furnace and increases the cost of production per unit of output.

Examples 10-11 differ from example 1 in that in the composition the amount of MgO was taken less than the boundary - 2.0 wt.% (Example 10) and more than the boundary - 7.0 wt.% (Example 11). At the same time, the properties of the glass worsened, namely, in example 10, its increased refractoriness up to 950 degrees C, decreased alkali resistance to 180 mg · dm ^-2 , and in example 11, the low resistance of the glass to water, is observed.

Examples 12-13 differ from example 1 in that in the composition the amount of B ₂ O _{3 was} taken less than the boundary - 9.6 wt.% (Example 12) and more than the boundary - 15.0 wt.% (Example 13). At the same time, the properties of the glass deteriorated, namely, in example 12, a decrease in alkali resistance to –180 mg · dm – ² , a decrease in the heat resistance of the glass and resistance to abrasive wear, and in example 13 — reduced resistance of the glass to water and alkalis are observed.

Examples 14-15 differ from example 1 in that the composition of the amount of Na ₂ O is taken less than the boundary - 18.0 wt.% (Example 14) and more than the boundary - 24.5 wt.% (Example 15). At the same time, the properties of the glass deteriorated, namely, in example 14, glass refractoriness is observed up to 950 ° C, a low coefficient of linear thermal expansion of 9.8 L · 10 ^-7 degrees, and in example 15 reduced water resistance to - 2.05 mg · dm ^-2 and low hardness - 4 according to Mohs, which makes the glass unsuitable for use as a protective coating on steel surfaces.

Examples 16-17 differ from example 1 in that in the composition the amount of CoO was taken less than the boundary - 0.4 wt.% (Example 16) and more than the boundary 1.0 wt.% (Example 17). At the same time, the quality of the glass in example 16 deteriorated, this is due to the low adhesion of the glass, and in example 17 the properties of the glass did not deteriorate, but an increase in the percentage of CoO is impractical due to the high cost of this material.

Examples 18-19 differ from example 1 in that in the composition the amount of ZnO was taken less than the boundary - 1.5 wt.% (Example 18) and more than the boundary - 5.0 wt.% (Example 19). At the same time, the properties of the glass worsened, namely, in example 18, a decrease in hardness to - 4 according to Mohs is observed, water resistance - to 177 mg · dm ^-2 and resistance to abrasive wear - 1.3 mg / kg of abrasive, and in example 19 there is a reduced alkali resistance glass.

Examples 20-21 differ from example 1 in that the composition of the amount of Fe ₂ O ₃ taken more than the boundary - 1.0 wt.% (Example 21), less than the boundary of 0.1 wt.% Can not be obtained due to the use of components for glass melting : quartz sand and dolomite containing impurities Fe ₂ About ₃ .

When the content of Fe ₂ O ₃ in the amount of 0.1 wt.% Glass has all the properties, as well as glass of optimal composition.

When the content of Fe ₂ O ₃ in an amount of more than 1.0 wt.%, There is a decrease in hardness to 4 according to Mohs, resistance to abrasive wear - 1.4 mg / kg of abrasive.

Thus, from table 2 it is seen that when the quantitative values of the ingredients go beyond the claimed range, the composition properties deteriorate compared to the optimal composition of the glass, which indicates the correct choice of boundary values.

The study of the inventive glass composition for the vitrification of steel pipes allows to reduce the cost of vitrification due to the lower cost of the glass composition provided by a simpler composition of the components.

It is important that the simplification of the composition does not impair the properties of the protective glass coating for steel pipes.

Table number 1 No. of example and composition SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO Br ₂ About ₃ Na ₂ O Soo Zno 1 47.00 3.00 0.10 7.80 4,50 12.30 21.60 0.70 3.00 2 45.00 4,50 0.40 8.50 3.20 13,20 21.70 0.50 3.00 3 49.00 1,50 0.50 8.50 3.00 12.10 22.00 0.90 2,50 4 44.00 3,50 0.45 8.75 4.90 12.90 22.00 0.50 3.00 5 50.00 3.20 0.40 7.10 3.00 11.80 21.50 0.50 2,50 6 48.00 1.00 0.65 8.50 4.05 12,20 21.90 0.70 3.00 7 48.00 5.50 0.45 7.05 3,50 11.80 20.70 0.50 2,50 8 47.70 3,50 0.40 5.00 5.00 12,20 22.50 0.70 3.00 nine 47.50 2,50 0.40 10.50 3.10 12.00 21.00 0.50 2,50 10 48.65 3,50 0.35 7.00 2.00 13.00 21.50 0.50 3,50 eleven 46.15 3.00 0.35 7.50 7.00 11.00 22.00 0.50 2,50 12 48.40 3.25 0.35 7.40 4.00 9.60 23.00 0.50 3,50 thirteen 47.35 3.05 0.40 6.00 4.00 15.00 21,20 0.50 2,50 14 47.90 4,50 0.40 8.50 4.00 13.00 18.00 0.70 3.00 fifteen 46.00 2,50 0.30 7.00 4.00 12.00 24.50 0.70 3.00 16 46.50 3.00 0.20 8.40 4.00 13.00 21.50 0.40 3.00 17 47.00 3.70 0.20 7.50 4.00 12.50 21.50 1.00 2.60 eighteen 47.05 3,50 0.45 8.00 4.40 13.00 22.00 0.60 1.00 19 47.60 3.00 0.40 7.00 3,50 12.00 21.50 0.50 4,50 twenty 47.50 3,50 0.10 7.00 4.00 12.00 21.70 0.70 3,50 21 46.60 3,50 1.00 7.00 4.00 12.00 21.70 0.70 3,50

Table number 2 Composition The coefficient of linear thermal expansion L × 10 ^-6 deg Firing temperature, deg. FROM Moocy hardness Abrasion resistance, mg / kg abrasive Water resistance cm ³ × g ^-1 Hydrolytic class of water resistance Alkali resistance, mhdm ^-2 Alkali Resistance Class 1 10.60 900 6 1,07 0.60 3 80 2 2 11.00 900 6 1.10 0.65 3 90 2 3 10.70 920 6 1,07 0.62 3 85 2 4 10.90 900 5 1.10 1.45 4 180 3 5 10.60 950 6 1.10 0.60 3 100 2 6 10.60 900 5 1.20 0.83 3 125 2 7 10.60 950 6 1.10 0.80 3 130 2 8 10.60 920 5 1.20 0.85 3 177 3 nine 10.80 900 6 1.10 0.80 3 165 2 10 10.60 950 5 1.20 1.20 4 180 3 eleven 10.60 930 5 1.30 1,50 4 176 3 12 11.10 920 5 1.20 1.90 4 180 3 thirteen 10.60 900 5 1.20 1.90 4 200 3 14 9.80 950 5 1.20 1.55 4 200 3 fifteen 11.40 890 4 1.40 2.05 5 250 3 16 10.60 900 5 1.20 1.80 4 177 3 17 10.60 900 6 1.10 0.85 3 174 2 eighteen 10.80 900 4 1.30 1.20 4 177 3 19 10.90 900 5 1.20 1.00 4 220 3 twenty 10.60 900 6 1.10 0.70 3 85 2 21 10.70 900 4 1.40 0.90 3 160 2

Claims (1)

Glass for the vitrification of steel pipes containing SiO ₂ , Al ₂ O ₃ , MgO, B ₂ O ₃ , Na ₂ O, ZnO, iron oxide, characterized in that it additionally contains CaO and CoO, in the following ratio, wt.% : SiO ₂ 45.0-49, Na ₂ O 19.0-23.5, Al ₂ O ₃ 1.5-4.5, CoO 0.5-0.9, CaO 6.0-9.5, ZnO 2.0-4.0, MgO 3.0-6.0, Fe ₂ O ₃ 0.1-0.9, B ₂ O ₃ 10.6-14.0.