JPS5842137B2 - Kouzou Zairiyou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle for drawing out glass fibers that has strength at high temperatures, is resistant to thermal shock, has excellent oxidation resistance, and is not easily wetted by glass.

In general, when materials with oxide as the main composition reach high temperatures, the excellent properties they have at room temperature deteriorate significantly, and there are few oxides that can maintain their properties at room temperature up to high temperatures.

For example, at a high temperature of 1200℃, the strength is 1/3 to 1/3 of the strength at room temperature.
The value will be 4.

In addition, oxide ceramics generally have low thermal shock resistance and are not suitable for use in places with high temperatures and severe temperature changes.

On the other hand, metal products that can withstand high temperatures of 1000°C or higher include heat-resistant alloys mainly made of W and Mo, some Ni-based alloys, and Pt, but although they have good thermal shock resistance, they have poor oxidation resistance at high temperatures. are considerably inferior except for Pt.

It also has low strength at high temperatures. Although platinum is widely used for glass fiber drawing nozzles, there is a desire to reduce the nozzle spacing, and the emergence of new materials is desired.

The present invention provides a glass fiber drawing nozzle made essentially of silicon nitride and having a porosity of 1.5% or less.

The porosity here is (1-sintered density/theoretical density) x 10
It refers to what is represented by 0.

The materials used in the present invention will be described in more detail.

Glass fiber drawing nozzles are used at high temperatures of 1000° C. or higher, and the most important issue is their strength.

The strength of many materials decreases as the temperature increases; for example, even high-purity alumina porcelain, which is known as a high-temperature material, has a strength of 1/3 to 1/3 of that at room temperature at around 1200℃. 4, and when we look at the bending strength numerically, at room temperature, it is about 40 kg/-, but it is 120 kg/-
10kg/m7 at 0°C? L or less, making it unsuitable as a high-temperature structural material.

For example, the material provided by the present invention is silicon nitride with a porosity of 1% or less, and its strength is 120 kg/mm1000 at room temperature.
Up to 1200°C, there is almost no change in strength.80
It has extremely high strength of more than kg/m4.

This material is usually produced by hot pressing.

In the case of silicon nitride, the strength tends to decrease as the porosity increases; for example, the strength tends to decrease as the porosity increases.
The strength at room temperature is 50kg/mt? 1 for t
At 200°C, it was about 30 kg/m4.

Next, in the case of glass fiber drawing nozzles, the thermal shock resistance is an important criterion for selecting the material.

The materials used in the present invention also exhibit excellent thermal shock resistance properties.

For example, in a repeated experiment of heating to 1200°C for 3 minutes in an oxidizing atmosphere followed by forced air cooling for 3 minutes, the silicon nitride of the present invention showed no change even after 50 repetitions, whereas high-purity alumina, for example, On the third try, cracks were observed.

It should be noted that the relationship between thermal shock resistance and porosity is not clear, and even silicon nitride with a porosity exceeding 10% could sufficiently withstand the above-mentioned thermal shock resistance.

The critical thermal shock temperature difference is 450°C for silicon nitride and 2200°C for high-purity alumina, indicating that the material of the present invention has excellent thermal shock resistance.

Next, the oxidation resistance of the material of the present invention will be described.

In structural materials used at high temperatures, it is generally undesirable that the oxidation resistance is weak, as this will significantly deteriorate the properties of the material.

There is no need to explain this if we look at the example of metals.

Although nitrides are generally said to have problems with high-temperature oxidation, the material of the present invention was found to have very good oxidation resistance.

Figure 1 shows the oxidation weight gain of the material of the present invention at 120 ml in air.

In the figure, A shows the oxidation weight gain of a silicon nitride composition with a porosity of 1.5.

Similarly, although not shown in the graph, the oxidation weight increase was similarly investigated for silicon nitride having a porosity of lOφ.

As a result, it was confirmed that the amount increased by 1.0 .mu./d after about 8 hours, and then increased at a rate of 0.31 n9/ffl after 10 hours.

When used as a structural material at high temperatures for a long period of time, oxidation weight gain beyond this level may significantly shorten the life, so lo% was determined as the limit for porosity.

FIG. 2 shows the results of measuring the bending strength of the material A in FIG. 1 at room temperature after the oxidation resistance test.

The glass was then tested for wetting.

As for the wettability with common borosilicate glass (main composition: SiO□ glass), as shown in the table above, the smaller the porosity, the larger the wetting angle.

For those with a porosity exceeding 10φ, the surface was altered as if the entire surface had been soaked with glass.

The following will be explained based on examples. Example Using silicon nitride, a material with a porosity of 0.2%, the content of silicon nitride is 95 yen and the remainder is yttrium oxide, and the diameter is 17Xl+! φ hole pitch 3
7Itm was used in a nozzle for drawing out glass fibers from borosilicate glass, and it was found to be excellent.

In particular, in the case of silicon nitride, the fiber drawing temperature is 120
At 0°C, the wetting angle with the glass is over 90°, making it possible to narrow the pitch spacing compared to platinum, which is conventionally used in drawer nozzles, making it possible to increase the number of holes per unit area, making it excellent for mass production. I was able to make a nozzle.

[Brief explanation of the drawing]

FIG. 1 is a characteristic curve diagram showing the oxidation resistance of the material used in the present invention, and FIG. 2 is a characteristic curve diagram showing the bending strength of the material used in the present invention. A...Silicon nitride composition.

Claims (1)

[Claims] 1. A glass fiber drawing nozzle made of a sintered body mainly made of silicon nitride with a porosity of 1.5φ or less.