SU738438A1 - Protective filling - Google Patents

Abstract

1. PROTECTIVE BACKGROUND for a sapphire light guide device-. Powder containing Al2Oj, characterized in that, in order to reduce dynamic viscosity and linear expansion coefficient, as well as to increase thermal stability, 5i02 and HjBpg were added to the backfill, whereby the backfill components for the same dispersion were: 0.05-0 1 mm. 2. Protective backfill according to claim 1, similar to that. What components are taken in the following weight.h ratio: Al20 50-60, SiO, 39-49, H, B O, 1-1.5.

Description

(L

with:

with oo

four

WITH

00 The invention relates to a measurement technique and can be applied to measure the temperature of liquid metals in metallurgy and foundry. Fiber optic devices are known in which aluminum based shieldings are used to reinforce light guides. Protective backfill is also known for a sapphire light guide device made of powder containing Al 12 O 3 C 2. In the known solution, the light guide of the device is protected by filling of alkali-free refractory oxides. . The protective charge is an integral part of the light guide device used to transfer heat radiation from the melt through the lining of the metallurgical unit to the outside of the radiation pyrometer. The light guide device, in addition to the protective filling, includes a light guide, a refractory tube, and a docking station with a pyrometer. The protective filling is filled with a right interstice between a light sapphire light rod and the inner surface of the refractory tube of the light guide device. The light guide device is permanently installed in the lining of the metallurgical unit with one end flush with the inner crucible slice in contact with the melt, and the other is taken out, thus, the device operates under conditions of thermal shock and a variable high temperature gradient along its length . Therefore, the protective backfill should not fuse with leucosapphire light with WATER during sintering and during operation or have the same thermophysical properties with it to prevent destruction of the light guide. During operation, the backfill must fit snugly to the side surface of the light guide to prevent melt flow along the fiber and to have sufficient heat resistance. Otherwise, during thermal shock, radial cracks are formed, which leads to penetration of the melt and destruction of the device. Requirements for protective backfill increase with decreasing lining thickness and increasing melt temperature in metallurgical aggr (egate, as the temperature gradient increases. However, the known backfill does not bake well in the operating temperature range and alloy with leucosapphire. Because of this, it does not ensure reliable operation of leucosapphire the light guide, since at temperatures and conditions of smelting black metals there is a high dynamic viscosity, low temperature resistance, a coefficient of foundry expansion, The 60 ° orientation coefficient of leuco-sapphire, which is used for optical fibers, does not bake well, which results in insufficient resistance to the effect of the melt, and is fused with leuco-sapphire. The combination of such characteristics leads to the fact that during operation of the light-guiding device in the unit lining with leu-ja the fiber breaks down when the temperature gradient changes along its length, poorly sintered backfilling is opened by the circulating melt, and there is a danger that the melt from the unit will break through the light guide device. During thermal shock, the immersion end of the device cracks and crumbles, the melt penetrates to the side surface of the optical fiber and destroys it during crystallization, which eventually also leads to the breakthrough of the melt. The purpose of the invention is to reduce the dynamic viscosity and the coefficient of linear expansion, as well as to increase thermal stability. This goal is achieved by the fact that Si02 and HjBOji are added to the composition of the filling, and the components of the filling are of the same dispersion: 0.050, 1 mm. The composition of the charge is taken at the following ratio of components, weight.h ,: A1gOz 50-60, SiOa 39-49, H, VOS1-1.5. The ratio of AljO to 5i02 determines the melting point of the backfill - 1800 ° C. Due to the fact that the backfill is cooled locally due to the Source of heat by radiation through a sapphire light guide, its thickness is insignificant (up to 8 mm, the thickness of the lining, starting from its inner surface, the temperature drops sharply, the backfill can be used to measure the melt temperature to 1750 ° C. To lower the temperature of plastic deformation of the sintered backfill introduced, the high content of HjBOj in the backfill leads to its intense reaction with the lateral surface of the sapphire light guide (heating of boric acid is accompanied By extracting boric anhydride, which, due to acts of dissociation and association with sapphire, accelerates irreversible processes in it. Boric acid is a strong sintering agent. When sintering backfill, it melts and provides sintering to the mass, which acquires the mechanical strength necessary for operation, depending on the amount of acid and sintering temperature. With increasing HjBOj content, the strength and sintering of the backfill increase. Based on these considerations and taking into account the limiting working temperature of the backfill, 1–1,5 weight HjBO is introduced / because of which the backfill is plastic in the working range of the melting temperatures of most metals. The size of the backfill particles largely determines the density.

3-4

10.6

1850

Example 1

9.1

50 60 1450

SiO,

39

80

8.0

1420

8.7 more than 1400 100

, 1 Note:

The ductility of the charge in the operating temperature range, the slight difference in its thermophysical properties from sapphire and the fact that it is not fused with sapphire prevent the sapphire rod from breaking when changing

20-23

17501850

1830

15-17 3-3,1

1400

16-18 2.3-2.8 1820

1400

17-19 1.6-2.5 1800

1400

temperature gradient across the thickness of the lining in the installation area of the light guide block.

The proposed filling composition was tested in a light guide device consisting of a refractory tube, the longitudinal axis of which was placed is known. The filling is fused with synthetic sapphire at a temperature of up to 1600 ° C, and the proposed composition does not fuse with a temperature of sapphire. sintering strength and temperature. Satisfactory characteristics of the sintered backfill, taking into account the upper limit of the operating temperature, are obtained if all components of the backfill have the same particle size O; 05-0.1 mm. The table shows 3 examples and physico-mechanical parameters of the proposed composition of the filling in comparison with the known. sapphire light guide. The gap between the light guide and the inner surface of the tube was filled with the proposed protective filling. Leucosapphire rods (d 6–8 mm and 200 mm) were used as light guides; the gauge thickness did not exceed 10 mm. The light-guiding devices were permanently installed in the furnace lining, one end flush with the internal lining cut, in contact with the melt. The other end was brought out. The heat radiation of the melt was removed through the lining and analyzed with a radiation irometer. The state of sapphire light guides was monitored visually and by the indications of the pyrometer compared with the thermocouple. The temperature of the melt (set) in the furnace varied from 900 to 1500 ° C. Tests have shown that leucosapphire light guides of light-diode devices did not break down during the whole furnace lining campaign (up to 2 months) and ensured continuous monitoring of the melt temperature (charges 7 in the furnace at all stages of smelting, furnace heating, overheating and melting. The backfill tightly encircled the sapphire light guide, but did not fuse with it. There was no melt leakage along the side surface. The backfill did not crack and weared evenly with the furnace lining. There was no melt flow from the furnace. The positive effect is that the filling of the proposed composition ensures reliable operation of the sapphire light guide and prevents the melt from breaking through the light guide block, which improves the accuracy of measuring the temperature of the melts and provides a safe way to measure the radiation pyrometry temperature Sapphire fiber optic blocks, permanently installed in the lining of metallurgical aggregates.

Claims (2)

1. PROTECTIVE FILLING for a leucosapphire light guide device made of powder containing A1 ₂ O ₃ characterized in that, in order to reduce dynamic viscosity and coefficient of linear expansion, as well as increase thermal stability, 5ϊ0 ₂ and Н3ВО3 are introduced into the composition of the filling, and the components of the filling taken the same dispersion: 0.05-0.1 mm. 2. The protective backfill according to claim 1, characterized in that the components are taken in the following ratio by weight: A1 ₂ O _L 50-60, SiO, 39-49, Н-В О, 1-1.5. ² 'm With SO oo