JPS61191541A - Preparation of thermal shock resistant shirasu glass - Google Patents

Abstract

PURPOSE:To prepare the titled glass having low melting point, high heat resistance and high bending strength by admixing B2O3 powder, if necessary, MgO powder or CaO powder and Li2O powder, with powdery SHIRASU, then heating at high temp., and heat-treating further for the removal of strain. CONSTITUTION:15-25wt% B2O3 powder is mixed with powdery SHIRASU, or 15-20wt% B2O3 powder, 5-6wt% MgO or CaO powder, and 0.5-1wt% Li2O powder are mixed with SHIRASU powder, then the mixture is heated at >=1,400 deg.C for>=1hr, then heat-treated for removal of strain.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention effectively utilizes whitebait, which exists in large quantities in nature and is considered to be a type of unused resource, to improve the production of whitebait, which is currently used in glass containers and other products. Acid glass differs in its composition,
The present invention relates to a method for manufacturing glass having higher heat resistance and impact resistance.

(Prior art) Shirasu, a type of silicate mineral that is widely distributed in Japan, mainly in the interior of Kyushu, is available in almost inexhaustible quantities, and much research has been conducted on its utilization. Shirasu is used in glass manufacturing only in a very limited number of fields, such as the method for manufacturing alkali-resistant glass found in Japanese Patent Publication No. 54-17338.The reason for this is that the chemical composition of Shirasu is As can be seen from the example of Yoshikawa glass in Kagoshima prefecture shown in the table, it contains a large amount of Fe2O3, which causes coloring problems, and furthermore, it contains a considerable amount of alkaline components such as Na2O and K2O, as well as a large amount of A1z03. Therefore, it has been thought that it is technically difficult to use it in the form of a glass.This time, we aimed to use it in a wide range of fields within the permissible range as a colored but heat-resistant Hfl glass. It's a small thing.

Next, Table 2 below shows the chemical compositions of major glasses currently on the market.

Comparing Table 1 and Table 2 above, there are 1203 people. Fe2
It can be seen that there are considerable differences in O3 and other components.

<Problems to be Solved by the Invention> In the present invention, by adding a specific component characterized by the B2O3 component to Shirasu, it is possible to manufacture thermal shock resistant glass that has not been used until now. The aim is to make effective use of whitebait, which is a type of resource.

Means for Solving the Problems In the present invention, in order to achieve the above object, B2O3 powder is mixed and adjusted to whitebait powder so that the B2O3 content is 15 to 25% by weight, and then the mixture is heated to 1400°C or higher. This is a method for producing heat-resistant and impact-resistant glass glass, which is characterized by heating at a temperature of 1 hour or more, and then further subjecting it to a heat treatment to remove strain. It is also possible to reduce the amount of MgO (or Cab) to 15 to 20% by weight, and instead use a mixed powder in which 5 to 6% by weight of MgO (or Cab) and 05 to 1% by weight of Li2O are added and mixed.

Effects> Shirasu itself has a chemical composition as shown in Table 1 above, and its melting point is extremely high at 1800° C. or higher, making it difficult to melt. If soda ash is added to and mixed with this shirasu, the melting point will be lowered, but the resulting glass has a very high coefficient of thermal expansion and cannot be used practically as a thermal shock resistant glass. However, when an appropriate amount of B2O3 is added to whitebait, the melting point is lowered and the coefficient of thermal expansion is small.
Glass with high bending strength can be obtained. That is, by adding B7O3 to the total amount of about 20 times the total amount, its melting point becomes 1400.
℃ or below, making it easy to melt. However, if it exceeds 25% by weight, the bending strength tends to decrease.

Also, unless it is added to replace a part of B2O3 and 120 is added in an amount of 0.5% by weight or more, it will not have the effect of lowering the melting point.
Also, if it exceeds 1% by weight, the strength will decrease, so the amount added should be 0.05 to 1% by weight, and M should be 0.005 to 1% by weight. Regarding CaO, a minimum amount of 5% by weight is required from the viewpoint of strength, but if it exceeds 6% by weight, the coefficient of thermal expansion becomes too large, so the amount added is 5 to 5%.
6% by weight. Therefore, B2O3 is reduced by the amount added.

<Example> *Example 1 Shirasu 80 using the dried Yoshikawa whitebait shown in Table 1 above.
After thoroughly stirring and mixing the mixed powder of 70% by weight and 19.30% by weight of B2O3, about 200% by weight was placed in a platinum dish containing 250ec.
e(H) and tamped in an electric furnace at a heating rate of 5°C.
/+++in to 1400°C, left for 1 hour, taken out from the furnace, and subsequently subjected to strain removal heat treatment.

This method of strain removal heat treatment involves storing a container with a lid made of stainless steel in a furnace prepared separately from the above-mentioned electric furnace, placing a container with a lid made of carbon in the furnace, and placing the container with a lid made of carbon inside the furnace. The surroundings of the molten glass were filled with fine coke and kept at 600°C. The molten glass in the platinum dish was placed in a carbon container with a lid and charged into the furnace.
A method was used in which the sample was held at 00°C for 30 minutes and then slowly cooled.

After cooling, take out and cut into 5 x 5 x 15 (mm)
After polishing, physical property tests were conducted.

*Example 2 Same whitebait as in Example 1 above, 75.60% by weight.

MgQ 5.42 heavy weight, LiO20, 90% by weight,
A mixed powder containing 18.08% by weight of B2O3 was placed in an electric furnace in the same manner as in Example 1, heated at 1450°C for 1 hour, and then subjected to strain removal heat treatment in the same manner as in Example 1. Samples were then cut out and subjected to physical property tests. I did it.

*Example 3 Everything was the same as in Example 2 except that a CaO component was used in place of the Mho component in Example 2 above.

The chemical compositions of the glasses obtained in Examples 1 to 3 are shown in Table 3 below, and the physical properties thereof are shown in Table 4 below.

Table 4 In Table 4 above, the physical property values of Pyrex and commercially available Kotop are also listed for comparison.

The resistance coefficient in Table 4 above is expressed as the bending strength divided by the thermal expansion coefficient at 300°C.

<Effects of the Invention> As described above, according to the present invention, B2
By adding the above-mentioned appropriate amounts of 0, MgO (Cab), and Li2O components, the melting point is lowered and melting becomes easier. Moreover, the coefficient of thermal expansion is small, the bending strength is high, and when compared in terms of resistance coefficient, it is superior to conventional glass. This makes it possible to obtain glass that is more resistant to thermal shock than other types of glass.

Patent applicant: Director of the Agency of Industrial Science and Technology (1 other person) Sub-agent Noriharu Ariyoshi

Claims (1)

[Claims] 1. For whitebait powder, B_2O_3 powder, B_2
O_3 After adjusting the mixture to 15 to 25% by weight, 1
A method for producing thermal shock-resistant glass glass, which comprises heating at a temperature of 400° C. or higher for 1 hour or more, and then further subjecting it to strain removal heat treatment. 2. MgO powder, Li_2O powder, B_2O_3 powder was mixed with 5 to 6% by weight of MgO and Li_2O to Shirasu powder.
0.5 to 1% by weight, B_2O_315 to 20% by weight, and the remainder is a shirasu component after mixing and adjusting, heating at a temperature of 1400°C or higher for 1 hour or more, and then further subjecting to strain removal heat treatment. Method for producing impact-resistant glass. 3. CaO powder, LiO_2 powder for whitebait powder,
B_2O_3 powder, CaO5-6% by weight, LiO_2
0.5 to 1% by weight, B_2O_315 to 20% by weight, and the remainder is a shirasu component after mixing and adjusting, heating at a temperature of 1400°C or higher for 1 hour or more, and then further subjecting to strain removal heat treatment. Method for producing impact-resistant glass.