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STUDY OF THE INFLUENCE OF OXIDES IN THE SIO2–AL2O3–
NA2O–TIO2–K2O–B2O3–Р2O5 SYSTEM ON THE DULLNESS OF
THE ENAMEL COATING.
Aripova M.Kh.
Naimov Sh.B.
Tashkent Institute of Chemical Technology, Tashkent, Uzbekistan
e-mail: shoxruxnaimov820@gmail.com
https://doi.org/10.5281/zenodo.13302093
To cover the dark color of the ground enamel, the enamel coatings should
be matte – muted. Haze is the process of turning transparent enamel into
opaque due to refraction, reflection and diffraction of light[1].
The more the enamel is suppressed, i.e. characterized by high covering
power, the more this affects the technical and operational properties of the
coating. It is known that with an enamel layer thickness of 0.3-0.5 mm, enameled
products can be subjected to significant deformations and sudden temperature
changes without fear of compromising the integrity of the enamel coating. When
the thickness of the enamel layer is about 1 mm, slight deformation of the
product or its sudden heating causes chipping of the enamel [2–3].
Also, the aesthetic appearance of the product depends on the dullness of the
enamel coatings, that is, the more dulled the enamel, the more beautiful the
appearance of the coating. Thus, suppression, in particular crystal suppression,
plays an important role in the technology of enameling household products[4].
Conventional silicate glasses have an average refractive index of n=1.52. For
jamming to be effective, the refractive index of the jammer must be either
greater than 1.8 or less than 1.4. In this case, it does not matter which of the
phases it is greater, the difference is important. Research [5–7] has identified a
number of substances whose refractive index satisfies the requirements.
The synthesis of glasses for coating enamels was carried out in laboratory
conditions. The basis was the SiO
2
–Al
2
O
3
–Na
2
O–TiO
2
–K
2
O–B
2
O
3
–Р
2
O
5
system.
The following raw materials were used for the synthesis of coating enamels;
Quartz sand, limestone, soda ash, shale, boric acid, titanium oxide, potash and
ammonium dihydrogen orthophosphate. The chemical composition of the raw
materials is presented in Table 1.
Table No. 1
Chemical composition of synthesized glasses
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Composition
No.
Chemical composition, mass %
SiO
2
Al
2
O
3
Na
2
O K
2
O CaO TiO
2
P
2
O
5
Fe
2
O
3
B
2
O
3
№1001
42,4 4,54
14,0
2,29 0,07 17,3 2,30 0,06
16,4
№1002
42,1 4,20
13,0
2,06 0,08 18,2 1,9
0,07
18,4
№1005
41,7 4,98
13,3
2,35 0.09 18,6 2,04 0.06
16,1
№1006
41,6 4,7
13,9
2,38 0,08 16,1 2,20 0.06
18,1
№1008
42,6 4,75
14,0
2,41 0,08 17,2 2,15 0,05
16,76
№1009
44,0 4,90
13,6
2,29 0,09 14,7 2,35 0,06
18,0
The frit was cooked in a laboratory oven heated using natural gas at
a temperature of 1350°C for 1 hour. The melt was poured into water and frit
granules were obtained. The physicochemical properties of enamel coatings are
given in Table No. 2
Table No. 2
Physico-chemical properties of enamel coatings
Compositi
on No.
Refractive
index, n
Whiteness
index, %
Аcid-
resistant,
Surface
tension,
Н/м10
-3
№1001
1,586
77,8
АА
2,39
№1002
1,605
80,5
АА
2,34
№1005
1,585
75,8
АА
2,48
№1006
1,571
69,5
АА
2,35
№1008
1,552
77,5
АА
2,39
№1009
1,577
68,1
А
2,37
When titanium dioxide (TiO
2
) is included in the enamel coating, it changes
the properties of the enamel depending on its charge number, in which titanium
dioxide can be 4- or 6-coordinated. Due to the coordination state of Ti+4 ions,
titanium dioxide acts as a suffocator in small alkaline compounds, so the dioxide
tries to keep titanium in the Ti+6 coordination state, which reacts to form rutile
or anatase. However, in conditions where the glass contains a lot of alkali,
titanium dioxide acts as a stabilizer. The binding of ions in enamel depends on
the energy of the glass structural lattice, the strength of the bond of cations with
oxygen, and the strength of the cation field. The Ti–O bond is important and
approaches the strength of the Si–O bond. To ensure communication between
the Si–O–Si and Ti–O–Ti systems, one Na
2
O (K
2
O) molecule must correspond to
one TiO
2
molecule[8].
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In the process of analyzing Tables 1 and 2, it was established that: titanium
dioxide acts as the main muffler, the necessary additives are introduced into the
synthesized glass frit and applied to the surface of the primed metal, and during
combustion at a temperature of 820–830
o
C titanium dioxide exhibits high
crystallinity and exhibits properties quenching due to the formation of anatase
and rutile. Using sample No. 1005, it was found that increasing the amount of
titanium dioxide has a positive effect on the crystallization process.
References:
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Низкотемпературные покровные эмали для стали и алюминия / Стекло и
керамика. 2008. № 2. с.32- 33.
2. Литвинова Е.И. Влияние коррозионной структуры поверхности,
образованной при подготовке стали к эмалированию, на качество
покрытия // Стеклоэмаль и эмалирование металлов. Выпуск I.
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