JPH01115839A - Forming mold for formed glass article - Google Patents

Abstract

PURPOSE:To provide a forming mold having a surface layer formed by dispersing two or more compounds selected from nitride, carbide, B compound and oxide in a substance composed at least of Pt and Cr, and giving a formed glass article having high precision without polishing after press-forming. CONSTITUTION:The surface layer of the above forming mold is formed of a substance composed of at least two components consisting of Pt and Cr and containing 5-40wt.% of Cr. Two or more compounds selected from nitride (e.g. TiN or TaN), carbide (e.g. TiC or TaC), B compound (e.g. TiB2 or ZrB2) and oxide (e.g. Al2O3 or ZrO2) are dispersed in said substance in an amount of 0.02-30vol.%. An intermediate layer containing one or more components selected from Ni, Ti, Ca, etc., and their mixture is interposed between said surface layer and the substrate base. The surface layer of the forming mold has dense texture, high hardness and strength, excellent chemical reaction resistance and good releasability of the press-formed glass article.

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. Regarding molds.

(Prior art) In general, when forming glass by press molding, pre-softened glass to be formed is placed (or The surface layer of the mold is transferred to the glass to be molded by placing the molded glass in a mold and heating and softening it, and then applying a predetermined pressure to the mold. 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 of the mold has no defects such as pores, and can be precisely processed into a dense and mirror-like surface. It is required to meet requirements such as maintaining sufficient hardness and strength at high temperatures.

Conventionally, materials for such molds include silicon carbide (S i C) and silicon nitride (S i C).
Ni) (Japanese Unexamined Patent Publication No. 52-45613), tungsten carbide (Japanese Unexamined Patent Publication No. 56-59641), and zirconium oxide (ZrOz) are used as base materials, and a platinum-rhodium (Pt-Rh) alloy is applied thereon. or platinum
A method in which a coating film of an iridium (PL-Ir) alloy is formed has been proposed (Japanese Patent Application Laid-Open No. 176930/1983).

(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 a heavy flint-based optical glass containing lead is used, it has high chemical reactivity with lead, making it difficult to mold into a high-precision glass molded body.

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. There was also the problem 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 has been a problem in that mold releasability from the glass molded product has been poor since 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 made of a substance consisting of at least two components, platinum (Pt) and chromium (Cr), and nitride, carbide, and boron. It is formed by dispersing a few (or two) selected from compounds and oxides.

In addition, it is preferable that platinum (Pt) and chromium (Cr) be contained in a small amount (the substance consisting of two components contains 5 to 5 chromium (Cr)).
40 wt%, and at least two compounds selected from the nitrides, carbides, boron compounds, and oxides are 0.0
2 to 30 vol% dispersed, and the nitride is TiN
, T a N, A 42 N, B N, S L 3
N4, HfN, NbN, ZrN, carbide is TiC1Ta
C, B4C, SiC, HfC, ZrC.

VC, boron compounds are T i B z, Z r B,,
V B2, NbB, TaBz, MnB, NiB5 F
eB, CrB,, CoB, oxide is ALO,, ZrO□
, Y2O3, and further contains nickel (N i ), titanium (T i ), chromium (Cr), molybdenum (Mo), and cobalt (Co) between the surface layer and the underlying base.
), titanium nitride (T i N), titanium carbide (TiC), silicon carbide (SiC), and a mixture thereof.

These surface layers and intermediate layers are formed on a substrate processed into a predetermined shape by a sputtering method, an ion blasting method, or the like. The film thickness is preferably about 0.05 to 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 to chromium, iridium (
If at least two compounds selected from nitrides, carbides, boron compounds, and oxides are dispersed in a platinum alloy to which Ir), rhodium (Rh), and gold (Au) are added, - It can withstand use in presses.

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 examples include stainless steel, tungsten carbide (WC), zirconium oxide (ZrOz), cermet, Silicon carbide (SiC), silicon nitride (SisN4), and the like 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, nitrides, carbides, boron compounds, oxides, specifically nitrides TiN5TaN, Aj
! N, BN, Si, N,, HfN, NbN, ZrN, carbide TiC% TaC, BaC, Sic, HfC.

ZrC, VC, boron compound TiB, ZrB,.

VB, ,NbB, ,TaB, ,MnB, NiB.

FeB, CrBt, CoB, oxide A1.03, ZrO
By dispersing at least two compounds selected from □ and Y2O3, it is possible to particularly improve the mold releasability from the glass molded body. The dispersion rate is 0.
The reason why the content of at least two compounds selected from nitrides, carbides, and boron compound oxides is less than 0.02 vol% lowers the hardness and tends to cause scratches, and the dispersion effect causes crystallization. It is difficult to obtain a sufficient effect of suppressing growth and preventing film roughness;
This is because if the content exceeds 1%, the 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. Upper mold 1
and the lower mold 2 are arranged inside the guide mold 3 so that their 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, and a base 2a and a surface layer 2b.

2b are arranged facing each other.

The bases 1a and 2a are made of tungsten carbide that has been made dense by HIP treatment during sintering, and is made into a cylindrical shape (
One end surface is ground into a concave spherical shape, and as a final finish, it is polished to a high-precision optical mirror surface using a diamond grindstone, and each is processed into a concave spherical surface with a predetermined radius of curvature (32+nm). did. The surface roughness of this concave spherical surface was 100 Å or less.

The concave spherical surfaces of the substrates 1a and 2a are coated with surface layers 1b and 2b of a predetermined thickness under predetermined film forming conditions using a sputtering device and 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
In order to further strengthen the adhesion between the base layers 1b and 2b, it is effective to clean the surfaces of the bases i1a and 2a by reverse sputtering prior to forming the surface layers 1b and 2b.

For example, in Example 1, the target is platinum (95 wt%)
- Chromium (5 wt%), zirconium nitride, titanium carbide, film thickness is 0.5 μm, and the film forming conditions at that time are argon gas pressure I Xl0-'T.

rr, film formation rate 800 people/lll1n, 4 people/m respectively
in, 4 people/1in, dispersion 1 vol%, distance between electrodes 1
00nn, and the number of rotations was 2Orpm.

Furthermore, in this example, ternary sputtering was described in which separate targets of platinum-chromium, zirconium nitride, and titanium carbide are sputtered simultaneously, but the three types of targets are arranged in a mosaic pattern and the dispersion is adjusted by adjusting the area ratio. A composite target may be used, or the target itself may be a platinum-chromium-zirconium nitride-titanium carbide dispersed target. In any case, the sputtering rates of each are considered and combined.

In this embodiment, the indoor mold 3 includes upper and lower mold bases 11a,
It is made of tungsten carbide similar to 2a.

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 embodiment are arranged between the base 11a and the surface layer 1b and between the base 2a and the surface layer 2, respectively.
b, between the first intermediate layer 1c and the second width id and the first
This differs from the upper mold 1 and lower mold 2 in FIG. 1 in that the width Jtij2c and the second intermediate Jti2d are interposed, but the structure is otherwise superior. The middle layer is shown as 2N, but
There may be only one layer or three or more layers. Put the middle layer on the front! Examples 11 to 13, 16 to 19, and 21 are examples in which the intermediate layer is 2N, and Example 14 is an example in which the intermediate layer is 2N.
．． 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 using the ion blating method under predetermined film forming conditions (vacuum level 5
l0-'T o r r, film formation rate 300 persons/mi
After forming the first intermediate layers 1c and 2c (film rg, 0.05 μm) made of titanium at a substrate voltage of -300 V), platinum (95 wt%) is deposited thereon by sputtering.
- Using 5 wt % chromium, zirconium carbide, and tantalum nitride as targets, surfaces J'W1b and 2b (thickness: 3.0 μm) were formed under the predetermined film forming conditions (described above).

In Example 20, after ion etching the groups ff1la and 2a, a film was formed on the concave spherical surface by the ion blating method under predetermined film formation conditions (nitrogen gas pressure 5
10-'T o r r, film formation rate 300 people/min,
Second intermediate R31d and 2d (thickness 0.3, I/m) made of titanium nitride were formed at a substrate voltage of -300 V). Next, the sputtering method was used to set the predetermined film forming conditions (argon gas pressure IXl0-'T or r,
A first intermediate layer lc, 2c (film*0.05 μm) made of nickel was formed at a film formation rate of 400 people/m1n), and then platinum (80 wt%)-chromium (10
wt%)-iridium (10wt%) alloy, zirconium oxide, and titanium boride as targets, surface layers 1b and 2b (film thickness 1
．． 0 μm) was formed into a film.

In other Examples, the intermediate layer and surface layer were formed by substantially the same method as these.

(The following is a blank space.) 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 uses the above-mentioned upper mold 1. A lower mold 2 and a guide mold 3 are provided, and a glass to be formed 4 is placed on the lower mold 2.

These molds 1, 2.3 are supported by a support base 6 also made of stainless steel via a holder 5 made of stainless steel and having a 14-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 placed on the outer periphery, and the push rod 7 is heated. The glass to be formed 4 is press-molded by lowering it onto the head of the upper mold 1. Temperature control is performed by measuring the mold temperature with a thermal lightning pair 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 -t% and Si
Oz: 27.8. Aj! zoi:2,0. Nago：
), 8+KzO: 1.2. P b O: (i5.2.
A heavy flint type optical glass (transition temperature 435°C) with T i O□: 260 was processed into a spherical glass lump with a diameter of 10 mm, and the mold temperature was 500°C in an N2 gas atmosphere at a pressure of 40 kg/ cIII was added for 30 seconds. Thereafter, 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 cooled to room temperature 2 to form a biconvex spherical lens. The molded glass body 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 each 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 repeatedly. 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, platinum-rhodium and platinum-
When press forming was performed in the same manner as in the above-mentioned example using forming molds each coated with a coating film of each iridium alloy, the releasability between the glass molded body and the forming mold was poor from the first press forming. A chemical reaction was observed at the mutual contact surfaces.

Although the shape of the surface layer of the mold has been described above as a concave spherical surface, the present invention is not limited to such a shape, and any shape such as a convex spherical surface, an aspherical surface, a flat surface, etc. may be used.

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 may 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 problem in its 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 adding at least two compounds selected from nitrides, carbides, boron compounds, and oxides to a substance consisting of at least two components, platinum and chromium. By being dispersed, it is possible to obtain good results in terms of density, hardness, strength, chemical reaction resistance, and area retention by suppressing crystal growth, and it also provides excellent compatibility with glass molded objects. Mold releasability is also improved.

[Brief Description of the Drawings] Fig. 1 is a cross-sectional view of a mold showing one embodiment of the present invention;
The figure is a sectional view showing another embodiment of the present invention, and FIG. 3 is a sectional view showing an example of the configuration of a press molding machine. 1. Bee upper mold, 1 a, 2 a-base, 1 b, 2
b - one surface layer, lc, Id, 2c, 2d - intermediate layer, 2.
2' - Lower mold. Applicant Tanaka Kikinzoku Kogyo Co., Ltd. Hoya Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (5)

[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 formed by press molding to form a glass molded object, in which the surface layer is made of at least platinum (Pt) and chromium (Cr). Nitride is a substance consisting of two components,
A mold for a glass molded article, characterized in that it is formed by dispersing at least two compounds selected from carbides, boron compounds, and oxides. (2) The surface layer is mainly composed of platinum (Pt) and chromium (C
A patent characterized in that at least two compounds selected from nitrides, carbides, boron compounds, and oxides are dispersed in a substance consisting of at least two components containing 5 to 40 wt% of r). A mold according to claim 1. (3) 0.02 to 30 vol% of at least two compounds selected from nitrides, carbides, boron compounds, and oxides
The mold according to claim 1 or 2, characterized in that the mold is formed in a dispersed manner. (4) Nitride is TiN, TaN, AlN, BN, Si_
3N_4, HfN, NbN, ZrN, carbide is TiC,
TaC, B_4C, SiC, HrC, ZrC, VC, boron compounds are TiB_2, ZrB_2, VB_2, Nb
B_2, TaB_2, MnB, NiB, FeB, CrB
_2, CoB, oxides are Al_2O_3, ZrO_2,
The mold according to claims 1 to 3, which is Y_2O_3. (5) An intermediate layer is provided between the base and the surface layer, and the intermediate layer is composed of nickel (Ni), titanium (Ti), and chromium (Cr).
), molybdenum (Mo), cobalt (Co), titanium nitride (TiN), titanium carbide (TiC),
5. The mold according to claim 1, wherein the mold is made of a material containing at least one selected from silicon carbide (SiC) and mixtures thereof.