JPH0424293B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a mold for press-molding glass, and particularly to a mold for molding into a high-precision glass molded body that does not require polishing after press-molding. (Prior art) Generally, when glass is formed by press molding,
A pre-softened glass to be formed is placed in a mold having a surface layer finished with a predetermined surface shape (for example, spherical or aspherical) (and the glass to be formed is heated and softened after being placed in the mold), By applying a predetermined pressure to this mold, the surface layer of the mold is transferred to the glass to be molded. Therefore, since the shape of the surface layer of the mold is directly transferred as the surface shape of the glass molded object, the surface layer has no defects such as pores and can be precisely processed into a dense and mirror-like surface. It is also required to satisfy requirements such as being able to maintain sufficient hardness and strength at high temperatures. Conventional materials for such molds include silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ) (Japanese Patent Laid-Open No. 52-45613), and tungsten carbide (Japanese Patent Laid-Open No. 56-59641). , which uses zirconium oxide (ZrO ₂ ) as a base material and on which a coating film of platinum-rhodium (Pt-Rh) alloy or platinum-iridium (Pt-Ir) alloy is formed (Japanese Unexamined Patent Publication No. 176930/1982) ) has been proposed. (Problem to be solved by the invention) However, although molds with a surface layer of silicon carbide or silicon nitride are dense and have excellent hardness and strength, they contain a large amount of lead in the glass to be molded. When using heavy flint-based optical glass containing lead, it has high chemical reactivity with lead.
It becomes difficult to form a glass molded body with high precision. Next, although tungsten carbide molds have excellent workability, they are susceptible to oxidation at high temperatures, causing roughness on the mold surface and making it impossible to maintain an optical surface. Another problem was that it easily reacted with the glass to be formed. In addition, it is said that the advantage of coatings formed with platinum-rhodium or platinum-iridium alloys is that they do not cause chemical reactions with the glass to be formed, but according to experiments conducted by the present inventors, There was a problem that the mold releasability from the glass molded body was poor from the beginning of press molding. (Means for Solving the Problems) In the mold for a glass molded article according to the present invention, the surface layer of the mold is formed by dispersing carbide in a substance consisting of at least two components, platinum (Pt) and nickel (Ni). This is what has been done. Note that platinum (Pt) and nickel (Ni) are preferably used.
The substance consisting of at least two components contains 5 to 45 wt% of nickel (Ni), and the carbide contains TiC,
Consists of at least one selected from TaC, B ₄ C, SiC, HfC, ZrC, and VC, and the amount of dispersion is 0.02 ~
Furthermore, between the surface layer and the underlying base, nickel (Ni), titanium (Ti), chromium (Cr), molybdenum (Mo), cobalt (Co),
An intermediate layer containing at least one selected from titanium nitride (TiN), titanium carbide (TiC), silicon carbide (SiC), and mixtures thereof is interposed. These surface layers and intermediate layers are formed on a substrate processed into a predetermined shape by a sputtering method, an ion plating method, or the like. Film thickness is 0.05~
The thickness is preferably about 10 μm. If it is too thin, it will be difficult to obtain a uniform film, and if it is too thick, not only will the film formation time become longer, but the surface condition of the film will become rough. In addition, if carbide is dispersed in a platinum alloy containing nickel, iridium (Ir), rhodium (Rh), and gold (Au) as a surface layer material, it can withstand even higher temperature presses. It becomes like this. The base material of the mold is not particularly limited as long as it satisfies the hardness, strength, heat resistance, etc. generally required for a base, and stainless steel,
Tungsten carbide (WC), zirconium oxide (ZrO ₂ ), cermet, silicon carbide (SiC) and silicon nitride (Si ₃ N ₄ ) can be used. Further, as long as the pressure during press molding does not cause a problem in deformation of the base, the base material may be the same alloy as the materials of the above-mentioned surface layer and intermediate layer. (Function) The surface layer of the mold of the present invention not only has good density, hardness, strength, workability, and chemical reaction resistance, but also has good releasability from a press-molded glass molded body. In addition, crystal growth is suppressed and film roughness is suppressed. That is, platinum-
Nickel alloy (platinum 50wt% or more, Nickel 5~
45wt%) contains carbides, specifically TiC, TaC,
By dispersing B ₄ C, SiC, HfC, ZrC, VC, etc., it is possible to particularly improve the mold releasability from the glass molded product and maintain surface precision.
The reason for setting the dispersion amount to 0.02 to 30 vol% is because if the carbide content is less than 0.02 vol%, the hardness will be low and scratches will easily occur, and the dispersion effect will be sufficient to suppress crystal growth and prevent film roughness. On the other hand, if it exceeds 30 vol%, the mold releasability from the glass molded article will deteriorate. Further, the intermediate layer has the effect of increasing the affinity between the base and the surface layer and extending the life of the mold. (Example) FIG. 1 is a sectional view of a mold showing an example of the present invention. The mold is composed of an upper mold 1 and a lower mold 2. The upper mold 1 and the lower mold 2 are arranged inside the guide mold 3 so that their respective outer peripheral surfaces slide on the inner peripheral surface of the guide mold 3. These upper mold 1 and lower mold 2 each consist of a base 1a and a surface layer 1b, a base 2a and a surface layer 2b, and the surface layer 1b,
2b are arranged facing each other. The bases 1a and 2a are made of tungsten carbide made dense by HIP treatment during sintering, processed into a cylinder (diameter 18 mm, height 28 mm), one end surface of which is ground into a concave spherical shape, and the final As a finishing touch, they were polished to a high-precision optical mirror surface using a diamond grindstone, and each was processed into a concave spherical surface with a predetermined radius of curvature (32 mm). The surface roughness of this concave spherical surface was 100 Å or less. The concave spherical surfaces of the substrates 1a and 2b were coated with surface layers 1b and 2b of a predetermined thickness under predetermined film forming conditions using a sputtering device and using targets having the material compositions of Examples 1 to 21 shown in the table. was formed. In addition, in that case, the bases 1a, 2a and the surface layers 1b, 2b
In order to further strengthen the adhesion with the surface layer 1
It is effective to clean the surfaces of the substrates 1a and 2a by reverse sputtering prior to forming the films b and 2b. For example, in Example 1, the argon gas pressure is 1×
10 ^-3 Torr, platinum-nickel 5wt as target
%, DClkw, deposition rate 500 Å/min, titanium carbide as a target, RF 400 W, deposition rate 5 Å/min (dispersion amount 1 vol%), distance between electrodes 100
The film thickness was 0.5 μm. In addition, in this example, we have described binary sputtering in which separate targets of platinum-nickel and titanium carbide are sputtered at the same time, but a composite target is used in which two types of targets are arranged in a mosaic pattern and the dispersion is adjusted by the area ratio. It is okay to do so. Furthermore, the target itself may be decentralized. In any case, the sputtering rate of each is taken into account when combining them. In this embodiment, the guide mold 3 is made of tungsten carbide, similar to the bases 1a and 2a of the upper and lower molds. FIG. 2 is a sectional view of a mold showing another embodiment of the present invention. The upper mold 1' and the lower mold 2' of this example have a first intermediate layer 1c, a second intermediate layer 1d, and a This differs from the upper mold 1 and the lower mold 2 shown in FIG. 1 in that a first intermediate layer 2c and a second intermediate layer 2d are interposed therebetween, but the other structures are the same. Although two intermediate layers are illustrated, the intermediate layer may include only one layer or three or more layers. Examples 11-13, 16-19 and examples with only one intermediate layer are shown in the table.
21, and an example in which the middle layer is two layers is shown as an example.
Shown as 14, 15 and 20. For example, in Example 11, these intermediate layers and surface layers are formed by ion etching the substrates 1a and 2a and then by ion plating under predetermined film forming conditions (degree of vacuum 5×10 ^-5 Torr, film forming rate 300 Å). /
min, base voltage -300V) and the first one is made of titanium.
After forming the intermediate layers 1c and 2c (film thickness 0.05 μm),
On top of that, platinum (95wt%) is added by sputtering method.
- Surface layers 1b and 2b (thickness: 3.0 μm) were formed using 5 wt% nickel and titanium carbide (TiC) as targets under the predetermined film forming conditions (described above). In Example 20, after ion etching the substrates 1a and 2a, the ion plating method was applied to the concave spherical surfaces of the substrates under predetermined film forming conditions (nitrogen gas pressure of 5×10 ^-4 Torr, film forming rate of 300 Å). /min,
Second intermediate layers 1d and 2d (film thickness: 0.3 μm) made of titanium nitride were formed at a substrate voltage of −300 V). Next, a sputtering method was used to form a film under predetermined film forming conditions (argon gas pressure 1×10 ^-3 Torr, film forming speed
400 Å/min) and the first intermediate layer 1 made of nickel.
c, 1c (film thickness 0.05μm) was formed into a film, and then platinum (80wt%)-nickel (10wt%) was formed using the same method.
%)-iridium (10 wt%) as an alloy and titanium carbide (TiC) as targets, surface layers 1b and 2b (film thickness 1.0 μm) were formed under the predetermined film forming conditions (described above). In other Examples, the intermediate layer and surface layer were formed by substantially the same method as these.

[Table] Next, how to use such a mold will be explained using the mold shown in FIG. 1 as an example. FIG. 3 is a sectional view showing the main parts of the press molding machine. This press molding machine includes the above-mentioned upper die 1, lower die 2, and guide die 3, and a glass to be formed 4 is placed on the lower die 2. These types 1, 2, and 3 are
It is supported by a support base 6 also made of stainless steel via a holder 5 made of stainless steel and having an H-shaped cross section. Reference numeral 7 denotes a push rod made of stainless steel. These are housed inside a quartz tube 8, and the molds 1, 2, 3 and the glass to be formed 4 are heated by an induction heating coil 9 arranged on the outer periphery. It is lowered to the head of the mold 1, and the glass to be formed 4 is press-molded. Temperature control is performed by measuring the mold temperature with a thermocouple 10 disposed inside the lower mold 2. Next, a specific example will be explained. As the glass to be formed 4, the glass composition is wt%.
_SiO2 : 27.8, _Al2O3 : 2.0, _Na2O : 1.8, _{K2O :}
1.2, PbO: 65.2, TiO ₂ : 2.0 heavy flint optical glass (transition temperature 435°C) was processed into a spherical glass lump with a diameter of 10 mm, and mold temperature was 500°C in an N ₂ glass atmosphere. A pressure of 40 Kg/cm ² was applied for 30 seconds. After that, the pressure is released, and the press-molded glass molded body is slowly cooled to the above transition temperature while in contact with the upper mold 1 and the lower mold 2, and then rapidly cooled to room temperature and formed into a biconvex spherical lens. The glass molded body thus formed is taken out from the mold. The above press molding method is similarly performed using the mold shown in FIG. Then, in the press molding machine shown in FIG. 3, the heavy flint glass was molded 1000 times under the same conditions as described above using the upper and lower molds having the surface layer or intermediate layer of Examples 1 to 21. I did it over and over again. As a result, for all molds of Examples, the glass molded product had good releasability from the mold, and no chemical reaction was observed on the contact surface with the mold.
The surface precision and mirror surface of the lower mold surface layer were maintained in their original state, and the surface precision of the glass molded body was 100 Å or less, and the transparency was also good. For comparison, press forming was carried out in the same manner as in the above-mentioned example using molds in which coating films of platinum-rhodium and platinum-iridium alloys were formed as surface layers. The mold release properties between the glass molded body and the mold were poor, and it was observed that a chemical reaction occurred at the mutual contact surfaces. Although the shape of the surface layer of the mold is described above as a concave spherical shape, the present invention is not limited to such a shape, and may be formed with a convex spherical surface, an aspherical surface, a flat surface, etc.
Anything is fine. In addition, the intermediate layer has the same effect as long as it contains the substance used in each of the above-mentioned examples as a main component. It can be something. Furthermore, since good results were obtained using heavy flint optical glass, which is relatively easy to cause chemical reactions, other optical glasses can also be molded using the mold of the present invention. It goes without saying that it can be done. Note that the surface layer of the mold of the present invention may be oxidized during film formation and press molding, but even if it is oxidized, there is no support for use. Moreover, some kind of coating layer may be further formed on the surface layer, and the coating layer may be interposed between the surface layer and the glass to be formed. (Effects of the Invention) According to the present invention, the surface layer of the mold is formed by dispersing carbide in a substance consisting of at least two components, platinum and nickel, which improves density, hardness, strength, and chemical resistance. Good results can be obtained in both reactivity and retention of surface precision by suppressing crystal growth, and the mold releasability from the glass molded body is also improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a mold showing one embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the present invention,
FIG. 3 is a sectional view showing an example of the configuration of a press molding machine. 1, 1'...Upper mold, 1a, 2a...Base, 1b,
2b... surface layer, 1c, 1d, 2c, 2d... middle layer, 2, 2'... bottom mold.

Claims (1)

[Scope of Claims] 1. A mold comprising a base and a surface layer, in which the shape of the surface layer is transferred to the glass to be molded by press molding to form a glass molded article, the surface layer comprising platinum (Pt) and nickel ( A mold for a glass molded article, characterized in that the mold is formed by dispersing carbide in a substance consisting of at least two components of Ni). 2. Claim No. 2, characterized in that the surface layer is formed by dispersing carbides in a substance consisting of at least two components, the main component of which is platinum (Pt) and 5 to 45 wt% of nickel (Ni). The mold according to item 1. 3 Carbide is TiC, TaC, B ₄ C, SiC, HfC,
The mold according to claim 1 or 2, characterized in that the mold is made of at least one selected from ZrC and VC and is dispersed at 0.02 to 30 vol%. 4 An intermediate layer is provided between the base and the surface layer, and the intermediate layer is made of nickel (Ni), titanium (Ti), chromium (Cr), molybdenum (Mo), cobalt (Co), titanium nitride (TiN). , titanium carbide (TiC), silicon carbide (SiC), and a mixture thereof. The mold described in section.