JPH05339030A - Silica glass composite material - Google Patents

Abstract

PURPOSE:To improve heat-stability by compounding silica glass with a specified amount of nonreactive, and high purity ceramic. CONSTITUTION:High purity synthesized silica glass is pulverized, and controlled to a prescribed grain size. The high purity ceramic fiber consisting essentially of nonreactive ceramic such as >=97wt.% Al2O3 ceramic or ZrO2 ceramic is controlled to prescribed fiber length. Then, the synthesized silica glass powder and the ceramic fiber are mixed by a prescribed weight ratio, and melted by heating, the excellent heat resistance silica glass composite material containing 0.01-40wt.% ceramic based on silica glass, having >=10<13.5> poise viscosity at 1150 deg.C and >=10<11.8> poise viscosity at 128 deg.C is obtained. Among these composite materials, the composite material having >=60% light-transmittance of 588nm wavelength in 1mm thickness is suitable as the glass for an electric-discharge tube.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silica glass composite having excellent heat resistance. [0002] Conventionally, quartz glass has a high purity,
Quartz glass for semiconductor industry, transparent quartz glass for optics, quartz glass for lamps, because of its extremely small coefficient of thermal expansion and excellent resistance to rapid heating and quenching, and high light transmittance, particularly ultraviolet light.
It has been used in various fields such as quartz glass for heat treatment jigs. As the raw material, natural quartz or the like was used for transparent quartz glass, and silica stone or the like was used for opaque quartz glass. In recent years, a technique for artificially synthesizing high-purity silica has been established, and high-purity silica glass has been produced using silicon tetrachloride or the like as a raw material. However, this silica glass (hereinafter referred to as synthetic silica glass) is superior to fused silica glass obtained by melting crystalline quartz such as quartz (hereinafter referred to as fused silica glass) in purity and the like, but is inferior in heat resistance. It had the drawback. In view of the above circumstances, the inventors of the present invention have earnestly studied to provide a silica glass which is a synthetic silica glass having heat resistance higher than that of fused silica glass. It has been discovered that the above drawbacks can be solved by compounding silica glass with a specific ceramic. An object of the present invention is to provide a novel silica glass composite having excellent heat resistance. The present invention for achieving the above object relates to a silica glass composite comprising a silica glass matrix and a non-reactive high purity ceramic. The "ceramics" of the present invention means ceramics having a melting point of about 2000 ° C. or higher and a small difference in refractive index or expansion coefficient from silica glass. The shape of this ceramic is preferably long fiber, short fiber, or whisker, but the same effect can be obtained even in the particle form. The term "non-reactive" refers to the property of not chemically reacting with silica glass at high temperature, particularly the property of not generating a reaction gas. [0009] It shall be included. On the other hand, "low purity" means that the alkali metal element and the transition metal element are 3 wt. % Ceramics. As the non-reactive high-purity ceramics, various kinds of ceramics can be mentioned, but magnesia type ceramics, alumina type ceramics, zirconia type ceramics and the like are preferable. The ceramics to be composited must have high purity. In the presence of impurities, recrystallization may occur at high temperature or impurities may diffuse to the outside. The most problematic elements as the impurities are alkali metals Li, Na,
K, and transition metal elements such as Cr, Cu, and Zn.
Table 1 shows basic physical property values of fiber-shaped ceramics and lump transparent synthetic silica glass which are preferable ceramics. [Table 1] * The melting point of silica glass in Table 1 above represents the softening point. The silica glass composite of the present invention contains 0.01 to 40 wt. %, Preferably 0.1-10 wt. %, And the viscosity at 1150 ° C. It The light transmittance of the synthetic silica glass composite is 60% at a thickness of 1 mm and a wavelength of 588 nm.
The silica glass composite described above is particularly useful as glass for discharge tubes for transparent metal halide lamps. In the above silica glass composite, the content of high-purity ceramic is 40 wt. %, It becomes difficult to form a transparent glass, and cracks easily occur due to the difference in thermal expansion coefficient between silica glass and ceramics. The content of high-purity ceramic is 0.01 wt. % Or less, no improvement in viscosity is observed. When the viscosity of the silica glass composite is less than the above range, the thermal deformation thereof at the time of high temperature use is large, and the use thereof is limited. When the silica glass composite is used in a field where high purity is not required, the silica matrix does not necessarily have to be synthetic silica glass, and fused silica glass may be used. In this case, the heat resistance of the silica glass composite is further improved. As described above, the silica glass composite of the present invention shows high viscosity,
It is useful as glass for heat treatment jigs and the like, and because of its excellent transparency, it is also useful as glass for metal halide lamp discharge tubes and mercury lamp discharge tubes. The silica glass composite of the present invention is obtained by, for example, pulverizing raw material silica glass, adjusting the particle size thereof, uniformly mixing with it non-reactive high-purity ceramics whose length and the like have been adjusted beforehand, and heating and melting It can be manufactured by a manufacturing method such as vitrification. Measurement of physical properties (1) Measurement of transmittance: HITACHI Model
A U-3210 spectrophotometer was used to measure light having a wavelength of 588 nm through a double-side polished sample having a thickness of 1 mm. (2) Viscosity measurement: ASTM No. Beam bending method according to C598, 1150 ℃ and 128
The viscosity at 0 ° C was measured. Examples 1 to 7 Purity 99.9999 wt. % Synthetic silica glass is crushed with a crusher to obtain a particle size of # 60-150.
(Tyler-mesh 0.25 mm to 0.105 mm)
Adjusted to. [0021] Table 2 shows the physical property values of the obtained silica glass composite. [Reference Example 1] [Table 2] [Embodiment 8] Table 3 shows the physical property values of the obtained silica glass composite. [Embodiment 9] [Embodiment 10] [Reference Example 2] [Reference Example 3] [Table 3] Note) The silica glass of Reference Example 4 is a commercially available ultra-high purity synthetic silica glass, and the silica glass of Reference Example 5 is a glass commercially available as quartz glass for the semiconductor industry. Examples 11 to 14 The synthetic silica glass powder of Example 1 has a purity of 99.99 wt. % Alumina powder (particle size 0.5
.About.5 .mu.m) for each 0 wt. %, 0.1 wt. %, 1 wt.
%, And 10 wt. %, And mixed uniformly with a V-type mixer. The mixture is placed in a vacuum furnace for about 180
Melt transparent vitrification was performed at a temperature of 0 ° C. to obtain a silica glass composite. Appearance inspection of the obtained silica glass composite,
The light transmittance and the viscosity at 1150 ° C. were measured. The results are shown in Table 4. Example 15 Purity 99.99 wt. % Magnesia powder (particle size 0.5 to 5 μm) was uniformly mixed with the synthetic silica glass of Example 1 in a V-type mixer, and the mixture was heated and melted to form a transparent vitrification. Visual inspection of the obtained silica glass composite,
The light transmittance and the viscosity at 1150 ° C. were measured. The results are shown in Table 4. [Embodiment 16] Visual inspection of the obtained silica glass composite,
The light transmittance and the viscosity at 1150 ° C. were measured. The results are shown in Table 4. [Table 4] According to the present invention, as is apparent from the above-mentioned embodiment, 0.01 to 40 w of non-reactive high-purity ceramics is used.
t. % It can be seen that the composite compounded with synthetic silica glass has high transparency and significantly improved viscosity. In particular, 0.1 to 10 wt. % Synthetic silica glass composite has high transparency,
Moreover, it exhibits excellent heat resistance superior to that of fused silica glass.

Claims (1)

Claims: 1. A matrix made of silica glass,
A silica glass composite composed of non-reactive high-purity ceramics. 2. A non-reactive high-purity ceramic is contained in an amount of 0.01 to 40 wt. %, The silica glass composite according to claim 1. 4. The silica glass composite according to claim 1, wherein the light transmittance is 60% or more at a thickness of 1 mm and a wavelength of 588 nm.