LU83120A1 - IMPROVEMENTS IN PROCESSES FOR TREATING REFRACTORY MATERIALS AND APPLICATION OF THESE IMPROVEMENTS - Google Patents

Description

-ίο 2103/8102.

METALLURGICAL RESEARCH CENTER -CENTRUM V00R RESEARCH IN DE METALLURGIE,

Non-profit association -Vereniging zonder winstoogmerk. In BRUXELLES, (Belgium).

Improvements in the treatment of refractory materials and application of these improvements.

The present invention relates to improvements in methods for treating refractory materials.

It is well known to constitute, in refractory materials of suitable composition, the internal coatings of tanks, conduits, enclosures, ovens, etc., intended to be brought into contact with solid, liquid or gaseous bodies found at particularly high temperatures.

It is also known to subject one or the other part of the internal face of these coatings to surface treatment, for example to the action of a plasma torch, in order to give them a particular property, for example improved resistance to abrasion.

However, such a method has the disadvantage of not being able to be used effectively in relatively small spaces, such as those inside, for example tubes of small internal diameter, and of not easily be limited to a very superficial fusion.

5 The present invention specifically relates to a method for surface treatment of refractory materials, even in the case where the free space for the implementation of the method of the invention is very small.

10 4 ·

The process which is the subject of the present invention is essentially characterized in that, on the part to be treated with refractory material, there is directed a laser radiation, the power and duration of which are adjusted to achieve a sub-perfect fusion of said part.

This treatment is carried out, in certain cases, preferably under a neutral or reducing atmosphere, in order to avoid possible oxidation of the refractory part treated.

20

It has been found that the refractories thus treated have a smoother and denser surface, which makes them more capable of withstanding wear and tear, in corrosive atmospheres. thermal gradients, shocks, etc ...

25

According to the invention, the envisaged part of the refractory can be treated by scanning it at an appropriate speed with laser radiation. The energy distribution in the cross section of this radiation can advantageously be adapted to the temperature to be obtained at the targeted refractory surface; the more the energy density locally increases in the radiation, the higher and faster the temperature rise of the target surface, the latter remaining superficial.

35

For example, use is made of radiation having a peak

K

Λ —f; '1

I J

- 3 - central energy density, possibly accompanied by one or more zones (most often concentric rings to the axis of the radiation) of energy density above average. The radiation from a CO 2 laser is particularly interesting because of its greater ability to transmit its energy to the target.

Also according to the invention and depending on the dimensions of the surface to be treated, use can be made of laser radiation "10 of larger diameter, capable of directly scanning a larger surface of the refractory.

It has been found advantageous, prior to the application of laser radiation, to deposit on the surface to be treated, a thin layer of a particular material, for example an oxide, an alloy or any other material whose fusion with the refractory or the presence on the refractory could prove advantageous, from any point of view.

This deposition can be done in any way, for example covering with a powder, by impregnation, soaking in or projection of a solution or suspension containing the said particular material.

The process, object of the present invention, is especially applicable to tubes, nozzles for continuous casting, or for emptying of bags, etc., the laser radiation being able to easily scan the entire internal surface of these tubes, nozzles, etc. ., thanks to a suitable mirror that is moved in the tube and along the axis of the tube (or the bu-sette) by rotating it around this axis, after 1 '; having tilted on it, so as to return on the internal face of the tube (or the nozzle), the laser radiation 1 which is directed on said mirror.

ï j, -fc— [- 4 -. · *

The depth of the inner layer of the tube concerned by the fusion is a function of the speed of travel of the ray and its intensity. We can, thanks to this possibility, ac-. significantly increase the longevity of certain tubes or nozzles.

In the more specific case of the nozzles for emptying the ladles, it has been found advantageous to deposit, prior to treatment, a thin layer of an appropriate oxide of * 10 better refractory quality, for example Ί, τΟ ^, on a relatively oxide inexpensive, said layer being particularly resistant to abrasion after treatment with laser radiation according to the invention.

- I

-4 · /

Claims (9)

1. Process for the treatment of refractory materials, charac-terized in that which is directed onto the part of the refractory to be treated, a laser radiation whose power and duration are adjusted to achieve a surface fusion of said part. 2. Method according to claim 1, characterized in that% 10 it is carried out under a neutral or reducing atmosphere. 3. Method according to either of claims 1 and 2, characterized in that said treatment is carried out by scanning, by means of laser radiation and at an appropriate speed of the targeted part. 4. Method according to either of claims 1 to 3, characterized in that the laser radiation has at least one peak of higher energy density. 20 5. Method according to either of claims 1 to 4, characterized in that the laser is of the CO ^ type. 6. Method according to either of claims 1 to 25 5, characterized in that, prior to the application of laser radiation, a thin layer of a particular material is deposited on the surface to be treated, by for example an oxide, an alloy or any other material whose fusion with the refractory or the presence on the refractory at the time of application of the radiation has any advantage. I i »4 \ \ \ - 2 -. * · 7. Method according to claim 6, characterized in that this deposition is done in any way, for example covering with a powder, impregnation, soaking, spraying of a solution or a suspension ... 5 8. Method according to either of claims 1 to 7, characterized in that the laser radiation reaches the part of the refractory to be treated, by means of one or more mobile optical references (for example mirrors) or * 10 no, and / or rotating or not. 9. Processes as described above. - ψ ^ Τ