JPH0421541A - Fluoride glass composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluoride glass that has good weather resistance (and can be formed at temperatures below 400°C), and can also be used as an infrared optical fiber or optical component. I can do it.

[Prior Art] Fluoride glass is a material that is transparent in a wide wavelength range from visible to infrared, and is expected to be used in infrared-transmitting optical fibers, lenses, and the like.

Furthermore, fluoride glass has a low melting point and has the advantage that it can be molded at a lower temperature than oxide glass. As the fluoride glass, ZrF4BaFz glass (Special public
(Japanese Patent Publication No. 62-59066) are known.

[Problems to be Solved by the Invention] However, the above-mentioned glass system had the following problems. Although ZrF4-BaFz glass can be formed at low temperatures below 400°C, it has poor weather resistance, moisture diffuses from the surface, and the glass becomes devitrified. In addition, although conventional glass systems mainly composed of AlF3 have good weather resistance, they are difficult to mold at temperatures below 400°C. This method has the disadvantage that a mold must be made of an alloy or ceramics such as SiC, making it difficult to stably and inexpensively manufacture a high-precision optical element.

The object of the present invention is to provide a glass composition that overcomes the drawbacks of the prior art described above.

[Means for Solving the Problems] The present invention was made to solve the above-mentioned problems, and in terms of mol%, AIF, 20-40% YF35-2
0% Total amount of LiF + NaF + KF is 5 to 15 mol%
MgFa 0-7% CaF20-25% 5rF20
~12% BaF20~12% MgF, + CaFx
+5rFz+ Pb with a total amount of BaFz of 15-40%
F, 0-10 mol% CdF20-10 mol% Pb
The present invention provides a fluoride glass composition characterized in that the total amount of F2+ CdF2 is 0 to 10 mol%.

In the present invention, AIFa is 25 to 40% in mol%
If it is less than 25% or more than 40%, it will not crystallize and become vitrified, and it is particularly desirable to keep it at 30 to 35% in order to prevent crystallization. YF is 5 to 20%, and if it is less than 5% but exceeds 20%, it will not crystallize and become vitrified, and it is desirable to keep it at 10 to 15% in order to prevent crystallization. A small amount selected from the group consisting of LiF, NaF, and KF (each type of fluoride is 5 to 15%,
If it is less than 5%, it cannot be molded at 400℃ or less, and 1
If it exceeds 5%, crystals tend to precipitate, making it impossible to produce a homogeneous glass. In particular, it is desirable to set the content to 7 to 12% in order to produce a homogeneous glass that can be molded at 400° C. or lower. MgFi 0-7% preferably 3-5% Ca
F20-25% preferably 5-20% 5rFzO-1
2% preferably 3-8% BaF20-12% preferably 3-8%, MgF2+ CaF2+ 5rFz +
15-40% in total amount of BaF2, preferably 21-35
% is desirable in terms of making it difficult to crystallize.

The total amount of PbF, +CdF2 is 0 to 10%, and if it exceeds 10%, it tends to crystallize and it is not possible to produce a homogeneous glass, so it is desirable to keep it at 2 to 7% to prevent crystallization. .

Furthermore, there is no problem with vitrification even if all or part of YF is replaced with lanthanide fluoride (LaF, GdF, YbF3, etc.).

[Function] In the present invention, AIFi is the main component constituting the glass network structure, YF acts as an auxiliary component, and P
bF* + CdFi works to complement the glass structure and stabilize it. LiF is a glass mesh modifying component, which lowers the glass transition temperature while preventing crystallization, thereby enabling molding at 400° C. or lower.

MgFi, CaF, 5rFt, BaF z are glass network modifying components that lower the melting temperature and facilitate vitrification. Also, it is composed of fluoride, which has low solubility in water, and has high weather resistance.

[Example] (Example 1) AIFi, PbFi, YFi, MgF as starting materials
x, CaFa, SrF2, BaFz, and LiF were used. As shown in Table 1, AIFa 35.0 mol% P
bF, 5.0 mol% YF3 13.0 mol% MgF
ffi 5.3 mol% CaFa 16.0 mol% Sr
F25.3 mol% BaF25.3 mol% LiF 1
A total of 20 g was weighed so that the ratio was 5.0 mol%, and the mixed raw materials were placed in a glassy carbon crucible.
After melting in an electric furnace at 50° C. for 2 hours in a N2 gas atmosphere, the crucible was allowed to cool, and then slowly cooled at 320° C. to obtain glass. In addition, the obtained glass was heated to N1-P at 350°C.
When press molding was performed using a plated stainless steel mold, it was possible to transfer the surface roughness of the mold.

(Examples 2 to 12) The compositions shown in Table 1 were melted in the same manner as in Example 1, and the obtained glasses could be press-molded in the same manner as in Example 1 at temperatures below 400°C. Table 1 shows Example 1 and Examples 2-
The glass composition, glass transition temperature, water resistance, and weather resistance of 12 were shown.

[Effects of the Invention] The present invention uses a mold that has high weather resistance, can be molded at temperatures below 400°C, and is easy to perform precision processing, such as a stainless steel mold with N1-P plating. This has the effect that high-precision optical elements can be manufactured stably and at low cost.

Claims (1)

[Claims] (1) AlF_325-40%YF_3 in mol%
5-20%LiF+NaF+KF total amount is 5-15 mol%MgF_20-7%CaF_20-25%SrF_2
0~12%BaF_20~12%MgF_2+CaF_
The total amount of 2+SrF_2+BaF_2 is 15-40%Pb
F_20-10 mol% CdF_20-10 mol% Pb
A fluoride glass composition characterized in that the total amount of F_2+CdF_2 is 0 to 10 mol%.