JPS648059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crucible material for melting optical glass.

Since the Pt-Au alloy has the advantage of not getting wet with glass, there has long been a desire to use it in crucibles for continuous glass melting.

However, in Pt-Au alloy, the melting point of Pt is 1772℃, and the melting point of Pt is 1772℃,
Since the melting point of Pt is 1063℃, which is a large difference, when solidifying after melting, Pt solidifies first, and Pt and Au tend to separate. Furthermore, when Pt and Au become a complete solid solution and are gradually cooled, the absorbed gas escapes and disappears. However, when welding is performed to make a crucible using a thin plate of this Pt-Au alloy material, the molten material is When solidifying, the molten part, surface layer, and parts with a high Pt concentration that are in contact with the atmosphere solidify first, and then the internal parts with a high Au concentration solidify, so the internal gas cannot escape completely, causing large and small defects in the welded area. The drawback was that a large number of various pinholes were generated and the strength was extremely reduced.

Therefore, optical glass melting crucibles made of Pt--Au alloys currently in use are limited to small shapes with no welded parts within the range where flat drawing or press drawing can be performed.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a crucible material for melting optical glass that can be welded without generating pinholes.

The optical glass melting crucible material of the present invention is Pt
Or add 0.5 to 10 w/o of Au to Pt alloy, and further add Y, Ti, Zr, Hf, Th, V, Nb, Ta, Gd, La,
If at least one of the elements such as Ca and B is Ca,
0.01~0.1w/o, 0.01~0.05w/o for B,
In the case of Y, Ti, Zr, Hf, Th, Gd, V, Nb, and Ta, they are added at a ratio of 0.05 to 3 w/o.

In the optical glass melting crucible material of the present invention, the reason why 0.5 to 10 w/o of Au is added to Pt or Pt alloy is to prevent the glass from getting wet.
This is because if it is less than 0.5 w/o, the glass and Pt will wet well and the addition of Au will have no effect, and if it exceeds 10 w/o, the melting temperature of optical glass is usually 1000° C. or higher, which causes problems in creep strength. In addition to Au
Ti, Zr, Hf, Th, V, Nb, Ta, Gd, La, Ca,
The reason for adding at least one element such as B is that when oxygen gas enters the molten metal, it reacts with the above elements to generate oxides, thereby eliminating oxygen in the molten metal. It is. In other words, by absorbing oxygen from the material, pinholes that occur during welding can be eliminated. In addition, the generated oxide will be dispersed in the weld zone as a reinforcing material for Pt. However, the amount added should be 0.01~0.1w/o for Ca and 0.01~0.1w/o for B.
0.05w/o, Y, Ti, Zr, Hf, Th, Gd, La,
The reason why V, Nb, and Ta are limited to 0.05 to 3 w/o is because they have no deoxidizing function when they are below the lower limit, and when Ca and B exceed the upper limit, it becomes impossible to process the material and the high temperature This is because the creep strength decreases, and Y, Ti, Zr, Hf, Th, Gd, La, V,
When Nb and Ta exceed the upper limit, the material becomes hard and brittle.
This is because it becomes easier for cracks to occur.

Next, in order to clarify the effects of the crucible material for melting optical glass according to the present invention, a welding test of a specific material and a conventional material will be explained. Pt-5w/oAu-1w/oGd, which is a specific material of the present invention
When we butted the edges of two 1mm thin plates made of the same material and welded overlay using a 0.7mm diameter welding rod made of the same material, we examined the cross section under a microscope and found that there were no pinholes at all. It was not recognized. Pt-5w/oAu, which is also a specific material of the present invention
−0.1w/oY, Pt−5w/oAu−0.2w/oZr, Pt−
5w/oAu−0.3w/oHf, Pt−5w/oAu−0.5Th,
Pt−5w/oAu−0.6w/oV, Pt−5w/oAu−
1w/oNb, Pt−5w/oAu1w/oTa, Pt−5w/
oAu−0.3w/oLa, Pt−5w/oAu−0.05w/
After rolling each material consisting of oCa, Pt-5w/oAu-0.05w/oB to a thickness of 0.8 mm, weld two thin plates of each material with a diameter of 0.7 mm by butting their edges together. Perform weld overlay using a rod,
When the cross section was examined under a microscope, no pinholes were observed.

However, the edges of 1 mm thin plates made of the conventional material Pt-5w/oAu were butted together, welding was performed using a welding rod of the same material with a diameter of 0.7 mm, and the cross section was examined using a microscope. As a result, many small pinholes were confirmed.

As can be seen from the above explanation, the optical glass melting material according to the present invention can be welded without generating pinholes, and a small amount of oxide generated during welding is dispersed in the welded area, so the strength of the welded area is It never declines. Therefore, there is an excellent effect that optical glass melting crucibles of various shapes and large sizes having welded parts that can withstand actual use can be manufactured.

Claims (1)

[Claims] 1 Adding 0.5 to 10 w/o of Au to Pt or Pt alloy,
Furthermore, Y, Ti, Zr, Hf, Th, V, Nb, Ta,
At least one of the elements such as Gd, La, Ca, B, etc.
0.01~0.1w/o for B, 0.01~0.01 for B
0.05w/o, Y, Ti, Zr, Hf, Th, Gd, La,
A crucible material for optical glass melting in which V, Nb, and Ta are added at a ratio of 0.05 to 3 w/o.