Glass composition, emission screen substrate and fireproff glazing

The subject of the invention is a glass composition, an emission screen substrate and anti-fog glazing. The glass composition according to the invention can be transformed into a glass ribbon that can be cut into panels, which in turn have good heat resistance. Such plates can be used for making primary glazing or they can be used as a substrate for the production of emission screens, plasma screens, elpktrolumikesnpknpjnpch screens and for cold cathode shields.

187 057

The glass currently used to make such substrates is a glass belonging to the group of silico-soda-lime glasses, commonly used for the production of glass for building and glazing of motor vehicles. While this type of glass is generally satisfactory when it comes to chemical resistance, flatness and defects, its temperature resistance is sometimes unsatisfactory.

During the production of emission screens, the substrate undergoes several heat treatments, which is aimed at stabilizing the dimensions of said substrate and binding a number of layers of various compounds, such as enamels, deposited on its surface. Binding of these layers of smaller or larger thickness requires that the substrate be subjected to a temperature higher than 550 ° C. While the expansion coefficient of the used silico-soda lime glass is of the same order as the expansion coefficients of the compounds deposited on its surface, its temperature resistance is insufficient and during heat treatment it must be placed on a ground plate to avoid deformation.

Glasses used for the production of fire-resistant glass usually belong to the group of borosilicate glasses. These glasses, which show very good heat and thermal shock resistance, are usually characterized by a low expansion coefficient. The latter property does not allow high stress in these glasses to be caused by heat toughening, and therefore increasing their mechanical resistance by this method is limited.

The present invention overcomes the above limitations.

According to the invention, the glass composition intended for the production of a thermally stable substrate or plate is characterized in that it comprises the following components in the following weight proportions:

<td>SiO2</td><td>45 to 68%</td>

<td>Al 2O3</td><td>0 to 18%</td>

<td>ZrO2</td><td>6.5 to 20%</td>

<td>Na 2 O</td><td>2 to 12%</td>

<td>K2O</td><td>&gt; 3.5 to 9%</td>

<td>CaO</td><td>1 to 13%</td>

<td>MgO</td><td>0 to 8%.</td>

the sum of the SiO oxides content₂, Al 2O3 and ZrO₂ remains equal to or less than 70%, the sum of the Na2O and K2O oxides content is equal to or greater than 8%, the composition optionally including BaO and / or SrO oxides in the following proportions:

11% &lt;MgO + CaO + BaO + SrO &lt;24% and in addition this composition has a lower stress decay temperature equal to or higher than about 530 ° C and a dilatation factor (a₂5-₃oO ° C) from 80 to 95 x 10 '⁷/ ° C.

This composition preferably contains the following ingredients as follows_cprop_orcj_ach _waweight:

SiO2 45 to 63%

Al 2O3 0 to 18%

ZrO2 6.5 to 20%

On₂4 to 12%

K₂3.5 to 7%

CaO 1 to 13%

MgO 1 to 8%.

Sum of Al 2O oxides₃ and ZrO2, which this composition contains, is preferably equal to or greater than 8%, and the ZrO2 content is in the range of 8 to 15%.

Preferably, the SiO2 weight content ranges from 45 to 59%.

The glass composition of the invention preferably contains the following ingredients in the following weight proportions:

SiO₂ 45 to 59%

A1₂ABOUT₃ 0dol0%

ZrO ₂ 8 ¢10 11%

Na2O 4doH%

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K₂3.5 to 7%

CaO 1 to 12%

MgO 1 to 7%.

the sum of the alkali oxides content remaining equal to or greater than 10%, the composition optionally containing BaO and / or SrO oxides in the following proportions:

14% &lt;CaO + MgO + BaO + SrO &lt;22% and in addition this composition has a lower stress decay temperature equal to or higher than about 550 ° C and a dilatation factor (a₂5_3oo ° C) from 82 to 95 x 10 '⁷/ ° C.

S_{uma concluded}ZrO oxide content₂ and Al2O3 which such composition contains, preferably in the range of 8 to 22% ο, and it has a viscosity corresponding to the log = 1.6 at a temperature equal to or lower than 1630 ° C, preferably 1 and 59 ° C. Preferably, the glass composition has a viscosity corresponding to the logo == 3.5 at a temperature equal to less than 12^about0 ° C, with preferably 1170 ° C; and it has a liquid temperature equal to or lower than the temperature corresponding to the viscosity of loge = 3.5.

According to the invention, the substrate for the emission screen obtained from a pane of glass cut out of a suggestive ribbon, decorated by a smooth tear with a medallion, shown by the composition of the peacock by the peacock

<td>SiO2</td><td>45 to 68%</td>

<td>Al 2O3</td><td>0 to 18%</td>

<td>ZrO2</td><td>6.5 to 20%</td>

<td>Naro</td><td>2 to 12%</td>

<td>KRO</td><td>3.5 to 9%</td>

<td>CaO</td><td>1 to 13%</td>

<td>MgO</td><td>0 to 8%.</td>

wherein the sum of the SiO2, Al 2O3 and ZrO2 oxides content is equal to or less than 70%, the sum of the Na2O and K2O oxides content is equal to or greater than 8%, the composition optionally containing BaO and / or SrO oxides in the following proportions:

11% &lt;MgO + CaO + BaO + SrO &lt;24% and in addition, this composition kyCyepj with lower stress decay temperature equal to or higher than about 530 ° C and msdialent dilation (a25-3oo0Q from 80 to 95 x 10'7 / ° C.

According to the invention, fire protection glazing made of a slab or glass pane cut out from a glass band, obtained 2 pizzas 2^gthesis^kcut glass in a bath made of solid metal, c^jnzalązr^kI am here^, that glasses with peacock feathers in pregnancy in weight proportions:

<td>SiO2</td><td>45 to 68%</td>

<td>A1₂O3</td><td>0 to 18%</td>

<td>ZrO 2</td><td>6.5 to 20%</td>

<td>NZ2O</td><td>2 to 12%</td>

<td>K2O</td><td>3.5 to 9%</td>

<td>CaO</td><td>1 to 13%</td>

<td>MgO</td><td>0 to 8%.</td>

whereby the sum of the SiO2, Al2O3 and ZrO2 oxides content is equal to or less than 70%, the sum of the Na2O and KrO oxides content is equal to or greater than 8%, the composition optionally containing BaO and / or SrO oxides in the following proportions:

% &lt;MgO + CaO + BaO + SrO &lt;24% and furthermore this composition has a lower stress decay temperature equal to or higher than about 530 ° C and a dilation factor (a25-30o ° C) of 80 to 95 x 10- / ° C.

Thus, the glass composition of the invention allows the production of plates or substrates whose deformation is virtually no when subjected to a temperature of 550-600 ° C.

187 057

The preferred glass composition according to the invention makes it possible to produce a plate inside which thermal stress can be created which is at least as high as that which forms in the plate of ordinary silico-soda-lime glass.

The glass composition according to the invention makes it possible to produce a substrate in which the surface loss of alkali ions is less than in a substrate made of ordinary silico-soda-lime glass.

This glass composition is suitable for melting and transforming into a glass ribbon floating in a metal bath under temperature conditions similar to those of ordinary silico-soda-lime glass.

It is usually assumed that the glass no longer has any sticky properties below the characteristic temperature called the lower annealing temperature, which corresponds to a viscosity of 10^{1 4,5} poise. For this reason, this temperature is a control point that allows you to assess the temperature resistance of glass. Due to the combination of components, such as results from the definition of the invention, glasses corresponding to this definition have a lower annealing temperature about 25 ° C higher than the temperature for classic silico-soda-lime glass. For most types of glass according to the invention, this difference is at least 45-50 ° C.

This combination of ingredients also allows obtaining glasses in which the expansion ratio is of the same order as the expansion ratio of traditional silico-soda-lime glass.

The glasses according to the invention also show an advantageous ability to melt and transform into a glass ribbon at a temperature close to that adopted in the production of classic silico-soda-lime glass.

For this reason, SiO 2 plays an essential role. In the context of the invention, the SiO 2 content should not exceed about 68%; above this value, the melting of the glassmaking mixture and the clarification of the glass require a high temperature, which causes accelerated consumption of refractory materials in furnaces. In addition, it was noted that increasing the S1O2 content is not conducive to raising the lower annealing temperature. Below 45% by weight of S1O2, the stability of the glasses according to the invention is insufficient. The glasses according to the invention, which melt the easiest, whose viscosities are best suited to the flow of glass in a molten metal bath and which show the highest lower annealing temperatures, contain 4559% SiO₂.

Aluminum oxide plays the role of a stabilizer. This oxide to some extent increases the chemical resistance of glass and promotes an increase in the lower annealing temperature. The percentage of Al2O3 should not exceed 20%, otherwise there is too much melting and unacceptable increase in the viscosity of the glass at high temperature.

ZrO2 also plays the role of a stabilizer. This oxide to some extent increases the chemical resistance of glass and promotes an increase in the lower annealing temperature. The content of Z1O2 should not exceed 20%, otherwise there is too much melting. Although this oxide is difficult to melt, it has the advantage of not increasing the viscosity of the glasses of the invention at high temperatures. This avoids the introduction of oxides, such as B2O3, into these glasses, which inter alia reduce the viscosity of the glass or the content of alkali oxides having the same effect.

In general, the melting of glasses according to the invention occurs within acceptable temperature limits with the proviso that the sum of the SiO oxides content₂, AL03 and ZrO 2 remain equal to or lower than 70%. Acceptable limits must be understood as glass temperature, corresponding to logri = 1.6, not exceeding approximately 1630 ° C, preferably 1590 ° C.

Of these glasses, some contain alumina and / or zirconia, others contain zirconia and / or alumina. To distinguish them further in the description, the first will qualify as glasses with aluminum oxide and the second glass with zirconia.

Glasses known as alumina glasses contain the following ingredients in the following weight ratios:

S1O2 415 to 68%

A1₂O3 2 to 20%

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<td>ZrO2</td><td>0 to 20%</td>

<td>B2O3</td><td>0.5 to 4%</td>

<td>On₂ABOUT</td><td>4 to 11%</td>

<td>K₂ABOUT</td><td>3.5 to 7%</td>

<td>CaO</td><td>1 to 13%</td>

<td>MgO</td><td>and up to 8%.</td>

wherein the sum of the SiO2, Al2O3 and Z1O2 oxides content is equal to or less than 70%, the sum of the Na20 and K2O alkali oxides content is equal to or greater than 8%, and said composition optionally comprises BaO and / or SrO oxides in such a ratio that

11% &lt;MgO + CaO + BaO + SrO &lt;24%

This group of glasses is distinguished in particular by the systematic presence of B2O3. Indeed, this oxide, as the lattice oxide, can be added or replaced with SiO2. It reduces the melting temperature of the glass making mixture as well as the viscosity of the glass at high temperatures. It also reduces the glass's ability to glazing, and in particular avoids raising the liquidus temperature. This reduction in viscosity action allows a sufficient interval between the glass forming temperature and its liquidus temperature to be maintained. Especially in the floating glass method, it is important that the liquidus temperature of the glass remains equal to or lower than the temperature corresponding to logn = 3.5, which is the case with this type of glass. More specifically, glasses of this type exhibit a temperature, corresponding to logn = 3.5, equal to or lower than about 1220 ° C, preferably 1170 ° C.

In this type of glass, the content of B 2 O 3 does not exceed about 4%, because above this value the escape of boron in the presence of alkali oxides during the melting of the glass may not be negligible. In this group of glasses, the sum of the content of Al2O3 and ZrO2 oxides is preferably equal to or higher than 5%. The sum of these oxides is preferably 8-22%.

Preferred alumina glass compositions contain the following ingredients as follows

<td colspan="2">weight proportions:</td>

<td>SiO2</td><td>45 to 59%</td>

<td>Al2O3</td><td>5 to 18%</td>

<td>ZrO2</td><td>0 to 17%</td>

<td>B₂O3</td><td>0.5 to 4%</td>

<td>On₂ABOUT</td><td>4 to 10%</td>

<td>K2O</td><td>3.5 to 7%</td>

<td>CaO</td><td>and up to 12%</td>

<td>MgO</td><td>1 to 7%.</td>

wherein the sum of the SiO2, Al2O3 and ZrO2 oxides content remains equal to or lower than 70%, the sum of the alkali oxides content is equal to or higher than 10%, said compositions optionally comprise BaO and / or SrO oxides in such a ratio that

14% &lt;MgO + CaO + BaO + SrO &lt;22% said glass compositions have a lower annealing temperature equal to or higher than 550 ° C and their expansion coefficient (a₂5-3oo ° C) is 85-95 x 10^:7/ ° C.

Glasses referred to as zirconia glasses contain the following ingredients in the following weight proportions:

SiO2 45 to 63%

Al 2O3 6.5 to 20%

ZrO 2 0 to 18%

On₂4 to 12%

K2O 3.5 to 7%

CaO and up to 13%

MgO and up to 8%.

the sum of the SiO oxides content₂, Al₂O3 and ZrO₂ remains equal to or less than 70%, the sum of the content of Na alkali oxides₂O and K.₂O is equal to or higher than 8%, said composition optionally contains oxides BaO and / or SrO in such a ratio that

187 057

11% &lt;MgO + CaO + BaO + SrO &lt;24% said glass composition has a lower annealing temperature equal to or higher than about 530 ° C and its expansion ratio (a25-3oo ° C) is 80-95 x 10 '⁷/ ° C.

In this group of glasses, the SiO2 content depends on the presence of other oxides also difficult to melt, such as ZrO2 and possibly Al2O3. Thus, the maximum SiO2 content should not exceed about 63%; above this value, the melting of the glassmaking mixture and the clarification of the glass require high temperatures, which causes accelerated consumption of refractory materials in furnaces. In addition, it was noted that an increase in the SiO2 content is not conducive to increasing the lower annealing temperature of the glass. Below 45% by weight SiO2, this type of glass has insufficient stability.

Zirconium oxide glasses that melt the easiest, whose viscosities are best suited to the flow of glass in a molten metal bath, and which exhibit the highest lower annealing temperatures, contain 45-59% SiO2.

As with alumina glasses, it has been found that the melting of zirconia glasses occurs within acceptable temperature limits, provided that the sum of SiO2, Al2O3 and ZrO2 oxides remains equal to or less than 70%. Acceptable limits should be understood as glass temperature, corresponding to logp = 1.6 and not exceeding approximately 1630 ° C, preferably 1590 ° C.

In zirconium oxide glasses, the sum of the AEO3 and ZrO2 oxides is preferably equal to or higher than 8%, and preferably 8-22%. The ZrO 2 content is preferably 8-15%.

Zirconia glasses are particularly distinguished from alumina glasses by the absence of boron oxide, because unlike Al2O3, the presence of even a high ZrO2 content in this type of glass does not increase their viscosity at high temperatures.

Zirconium oxide glasses also have the advantage of being easily adapted to the melting methods associated with the method of flowing glass in a bath of molten metal. Indeed, it turns out that these glasses cause low corrosion of AZS-type refractory materials (alumina-zirconia-silicon oxide) usually used in this type of furnace. In this way, the glasses optimize the life of the furnace.

Preferred zirconia glass compositions contain the following ingredients in the following weight proportions:

<td>SiO2</td><td>45 to 59%</td>

<td>ZrO2</td><td>8 to 15%</td>

<td>A12O3</td><td>0 to 10%</td>

<td>Na 2 O</td><td>4 to 10%</td>

<td>K2O</td><td>3.5 to 7%</td>

<td>CaO</td><td>1 to 12%</td>

<td>MgO</td><td>1 to 7%.</td>

wherein the sum of the contents of SiO2, Al2O3 and ZrO2 oxides remains equal to or lower than 70%, the sum of the content of alkali oxides is equal to or higher than 10%, said compositions optionally comprise BaO and / or SrO oxides in such a ratio that

14% &lt;MgO + CaO + BaO + SrO &lt;22% said glass compositions have a lower annealing temperature equal to or higher than 550 ° C and their dilatation coefficient (25-25 ° C) is 82-95 x 10'7 / ° C.

In general, the effect of other oxides on the glass's ability to melt and flow in a metal bath as well as their properties is as follows:

The Na2O and K2O oxides allow the melting temperature of the glasses according to the invention and their viscosity to be maintained at high temperatures within the limits previously defined. To do this, the sum of these oxides remains equal to or greater than about 8%. Compared to ordinary silico-soda-lime glass, the simultaneous presence of these two oxides in glasses of this type sometimes in similar proportions allows for a significant increase in their chemical resistance, and more specifically in their hydrolytic resistance as well as their specific resistance. Increasing the specific resistance of glasses is interesting in some applications, more precisely, when they serve as a substrate for making cold cathode shields. In these screens

187 057 surface electric fields are created that cause local electron clusters. Such clusters can cause unwanted migration of alkaline compounds in the reaction when the specific resistance of the glass is insufficient, as is the case with ordinary silico-soda-lime glass.

Alkaline earth oxides incorporated into the glasses of the invention generally have an effect of increasing the lower annealing temperature and this is the reason why the sum of their weight content should be at least 11%. Above about 30 °, the glazing ability of the glasses may increase to a degree which is not compatible with the method of flowing in a metal bath. To maintain glass glazing within acceptable limits, the CaO and MgO content should not exceed 13 and 8% respectively. The MgO content is preferably equal to or lower than 5%.

MgO, CaO and, to a lesser extent, SrO allow an increase in the lower annealing temperature; BaO and SrO allow increasing the chemical resistance of the glasses according to the invention as well as increasing the specific resistance. BaO also reduces the melting temperature as well as the viscosity of the glasses at high temperatures,

The benefits presented by the glass compositions of the invention can be better assessed by the examples shown in the attached tables 1 and 2.

Glass No. 1 corresponds to a composition of classic silicon-soda-lime glass used for the production of glass tape according to the method of floating glass in a molten metal bath; Glass No. 2 corresponds to the known borosilicate glass. Glasses 3 to 13 explain the glass compositions of the invention. The lower annealing temperature Ti, dilatation coefficient, viscosity and liquidus temperature as well as hydrolytic resistance (DGG) and specific resistance were measured by methods well known to the skilled person.

As the examples show, the viscosity and liquidus characteristics in the glasses according to the invention are similar to those of the reference glass in order to be able to melt and transform it into a tape in virtually the same conditions.

Thus, the glasses according to the invention are obtained by the method of floating glass in the form of a tape with a precisely adjustable thickness, which can vary from 0.5 mm to 10 mm. Said tape is cut into boards of the desired format before undergoing thermal treatment, designed to stabilize the dimensions of the listed boards. These boards are ready to serve as a substrate that withstands the application of various layers and the thermal treatment required for their binding.

These sheets or panels after thermal toughening can be combined to obtain insulating glazing or multilayer glazing. Insulating glazing is created from boards joined in two by means of an inserted glued profile. The method of their installation in the boxes supporting them is such that when exposed to flames, the edge of the plate from the side of fire is immediately exposed or in each case with a short delay to thermal radiation or the flames themselves, which reduces the thermal stress that usually arises in the plate, when it heats up more inside than at the edges. The combination of good-quality thermal toughening and the assembly in question allows such glazing to be kept in place long enough to meet applicable standards.

Multilayer glazing is made by joining panels with inserted plastic film; commonly used glass plates are also thermally toughened.

Table 1

<td></td><td>No. 1</td><td>No. 2</td><td>No. 3</td><td>No. 4</td><td>No. 5</td><td>No. 6</td><td>No. 7</td><td>No. 8</td>

<td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td>

<td>SiO₂</td><td> 71,7</td><td> 81,0</td><td> 60,9</td><td> 66,6</td><td> 53,6</td><td> 46,9</td><td> 51,1</td><td> 48,5</td>

<td>A1₂0₃</td><td> 0,6</td><td> 2,2</td><td> 5,7</td><td> 3,0</td><td> 10,0</td><td> 18,0</td><td> 12,0</td><td> 14,8</td>

<td>ZrO₂</td><td></td><td></td><td></td><td></td><td> 2,0</td><td></td><td> 1,9</td><td> 2,0</td>

<td>with H2O₃</td><td></td><td> 13</td><td> 3,5</td><td> 3,4</td><td> 2,2</td><td> 3,5</td><td> 1,7</td><td> 2,3</td>

<td>Na 2 O</td><td> 13,9</td><td> 3,6</td><td> 5,5</td><td> 9,6</td><td> 5,2</td><td> 4,7</td><td> 4,7</td><td> 5,3</td>

187 057

cd of table 1

<td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td><td> 8</td><td> 9</td>

<td>K₂ABOUT</td><td></td><td> 0,2</td><td> 6,2</td><td> 4,1</td><td> 6,2</td><td> 6,2</td><td> 6,8</td><td> 6,5</td>

<td>MgO</td><td> 4,1</td><td></td><td> 4,2</td><td> 6,7</td><td> 4,2</td><td> 3,0</td><td> 3,7</td><td> 3,8</td>

<td>CaO</td><td> 9,5</td><td></td><td> 6,8</td><td> 6,6</td><td> 6,8</td><td> 7,5</td><td> 6, 8</td><td> 6,6</td>

<td>SrO</td><td></td><td></td><td> 4,4</td><td></td><td> 7,0</td><td> 7,2</td><td> 7,6</td><td> 7,0</td>

<td>BaO</td><td></td><td></td><td> 2,8</td><td></td><td> 2,8</td><td> 3,0</td><td> 3,7</td><td> 3,2</td>

<td>T (° C)</td><td> 507</td><td> 510</td><td> 540</td><td> 531</td><td> 580</td><td> 579</td><td> 577</td><td> 582</td>

<td>T (logn = 7.6) (° C)</td><td> 725</td><td> 821</td><td></td><td></td><td></td><td></td><td></td><td> 830</td>

<td>and (XLO '⁷/ ° C)</td><td> 88,5</td><td> 32</td><td> 84,5</td><td> 80,5</td><td> 84,0</td><td> 86,0</td><td> 88,5</td><td> 88,0</td>

<td>Logp (Ω. Cm) (at 250 ° C)</td><td> 6,6</td><td></td><td></td><td></td><td></td><td></td><td></td><td> 8,7</td>

<td>DGG (mg)</td><td> 30</td><td></td><td></td><td></td><td> 7</td><td></td><td></td><td></td>

<td>T (logn = 1.6) (° C)</td><td> 1550</td><td> &gt;1800</td><td> 1566</td><td> 1579</td><td> 1584</td><td> 1559</td><td> 1554</td><td> 1546</td>

<td>T (logr | = 3.5) (° C)</td><td> 1085</td><td></td><td> 1113</td><td> 1119</td><td> 1156</td><td> 1160</td><td> 1159</td><td> 1162</td>

<td>^T liquidus (° C)</td><td> 1020</td><td></td><td> 1060</td><td> 1110</td><td> 1120</td><td> 1100</td><td> 1120</td><td> 1120</td>

Table 2

<td></td><td>No. 1</td><td>No. 2</td><td>No. 9</td><td>No. 10 *</td><td>No. 11 *</td><td>No. 12 *</td><td>No. 13 *</td>

<td>SiO₂</td><td> 71,7</td><td> 81,0</td><td> 54,6</td><td> 52,0</td><td> 53,05</td><td> 52</td><td> 52</td>

<td>A1₂ABOUT₃</td><td> 0,6</td><td> 2,2</td><td> 3,0</td><td> 4,0</td><td> 3,25</td><td> 2</td><td> 5,0</td>

<td>ZrO₂</td><td></td><td></td><td> 10,0</td><td> 11,0</td><td> 9,25</td><td> 5</td><td> 4</td>

<td>B₂ABOUT₃</td><td></td><td> 13</td><td></td><td></td><td></td><td></td><td></td>

<td>On₂ABOUT</td><td> 13,9</td><td> 3,6</td><td> 6,0</td><td> 7,0</td><td> 4,25</td><td> 4,0</td><td> 5,0</td>

<td>K₂ABOUT</td><td></td><td> 0,2</td><td> 6,9</td><td> 5,0</td><td> 6,05</td><td> 8,0</td><td> 6,0</td>

<td>MgO</td><td> 4,1</td><td></td><td> 4,2</td><td> 7,0</td><td> 2,05</td><td> 4,0</td><td> 5,0</td>

<td>CaO</td><td> 9,5</td><td></td><td> 3,5</td><td> 9,0</td><td> 7,2</td><td> 8,0</td><td> 10,0</td>

<td>SrO</td><td></td><td></td><td> 8,0</td><td> 3,0</td><td> 9,15</td><td> 9,0</td><td> 7,0</td>

<td>BaO</td><td></td><td></td><td> 3,8</td><td> 2,0</td><td> 5,75</td><td> 8,0</td><td> 6,0</td>

<td>T, (° C)</td><td> 507</td><td> 510</td><td> 606</td><td> 600</td><td> 612</td><td> 574</td><td> 575</td>

<td>T (logn = 7.6) (° C)</td><td> 725</td><td> 821</td><td></td><td></td><td></td><td></td><td></td>

<td>and (xl0 '⁷/ ° C)</td><td> 88,5</td><td> 32</td><td> 81,5</td><td> 84</td><td> 81,5</td><td> 93,5</td><td> 91,3</td>

<td>Logp (Q. cm) (at 250 ° C)</td><td> 6,6</td><td></td><td> 9,7</td><td> 9, 65</td><td> 10,7</td><td> 11,3</td><td> 10,7</td>

<td>DGG (mg)</td><td> 30</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td>T (iogn = i, 6) (° c)</td><td> 1550</td><td> &gt;1800</td><td> 1554</td><td> 1450</td><td> 1539</td><td> 1413</td><td> 1415</td>

<td>T (logn = 3.5) (° C)</td><td> 1085</td><td></td><td> 1192</td><td> 1120</td><td> 1172</td><td> 1078</td><td> 1072</td>

<td>^Tliquidus (° C)</td><td> 1020</td><td></td><td></td><td> 1360</td><td> 1120</td><td></td><td></td>

"*" No. 10-13 - theoretical compositions.

UP Department of Publications. Circulation of 50 copies

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