GB2103661A

GB2103661A - Heat-reflecting wending protection filter

Info

Publication number: GB2103661A
Application number: GB08222241A
Authority: GB
Inventors: Ulrich Werner; Werner Bartsch; Raimer Lindner; Heinz Schicht; Reiner Leuteritz; Johannes Reimann; Horst Schmidt
Original assignee: Flachglas Torgau GmbH
Current assignee: Flachglas Torgau GmbH
Priority date: 1981-08-03
Filing date: 1982-08-02
Publication date: 1983-02-23
Also published as: DE3228030A1; LU84304A1; HU190810B; DK336182A; DD206460A3; FR2510398B1; BE894014A; DE3228030C2; NL8203085A; GB2103661B; YU172282A; ATA289582A; FR2510398A1; AT386334B

Abstract

In a filter of the type comprising a layer of aluminium which has been vapour deposited in a high vacuum on one side of a conventional welding protection filter, on to the thin layer of aluminium there is vapour deposited a dielectric double-layer system, the materials of the two dielectric layers differing in their heteropolar and monopolar bonding components, a dielectric layer of a material with a lower heteropolar bonding component e.g. zirconium dioxide or silicon monoxide first having been vapour deposited on the layer of aluminium and then on this a dielectric layer of a material with a higher heteropolar binding component e.g. magnesium fluoride. The resulting filter has good mechanical and corrosion resistance without the need to provide an additional protective disc, high infra red reflection with increased reflection in the visible range and high u.v. stability, permitting low-contrast observation of the welding puddle.

Description

SPECIFICATION Heat-reflecting welding-protection filter The present invention is concerned with a heat-reflecting welding-protection filter for use as an eye-protection agent when carrying out welding operations.

Conventional welding-protection filters made, for example, of glass only provide a very limited protection against heat radiation occurring when welding, especially heat radiation in the infra-red range of 780 to 2500 nm, the result being the appearance of tiredness in the eyes of the welder in the case of continuous stressing and particularly in the case of special welding processes, such as inert gas welding.

This deficiency of conventional welding-protection filters can be reduced, for example, by applying thin metal layers, for example of gold or aluminium, to the side of the filter remote from the eyes of the welder.

Besides the necessary infra-red reflection in the above-mentioned range, it is to be expected of such layers that they will be resistant to chemical and mechanical influences and, in addition, that the protection provided by the welding-protection filter will not change during use.

Thus, for example, according to Federal Republic of Germany Patent Specification No. 2,440,468, the heat-reflecting layer is protected against mechanical influences by an additional protective disc and thus, in addition to the expense of the coating, a further expense has to be taken into account.

The desirable replacement of the noble metal gold by, for example, aluminium cannot be used because the mechanical and corrosion resistance of aluminium applied in the necessary layer thickness is completely inadequate and, consequently, the degree of light transmission T and thus the degree of protection during use of the welding-protection filter changes.

A high-contrast welding puddle is regarded as being especially harmful to the eyes of the welder.

The reflection in the visible range of from 380 to 780 nm, which is still relatively low, for example, in the case of a gold coating, can be regraded as being a measure of a low-contrast or high-contrast welding puddle in the case of observation through a welding-protection filter.

It is an object of the present invention to provide a heat-reflecting welding-protection filter which does not sufffer from the above mentioned disadvantages of known filters, which can be produced without greatly increased expense and which is an effective eye-protection agent when carrying out welding operations.

A further object of the present inventon is to provide a heat-reflecting welding-protection filter with a high degree of reflection in the infra-red range of from 780 to 2500 nm thus a reduced inherent heating up in the case of welding operations for long period of time, with a good mechanical and corrosion resistance without additional expenses arising, for example due to the provision of a protective disc, with a high ultra-violet stability and an increased degree of reflection in the visible range of from 380 to 780 nm for the purpose of achieving a low-contrast welding puddle in the case of observation through the welding-protection filter, use being made of materials which do not contain noble metals.

Thus, according to the present invention, there is provided a heat-reflecting welding-protection filter comprising a layer of aluminium which has been vapour-deposited in a high vacuum on one side of a conventional welding-protection filter, wherein on to the extremely thin layer of aluminium there is vapour deposited a dielectric double-layer system, the materials of the two dielectric layers differing in their heteropolar and homopolar bonding components, a dielectric layer of a material with a lower heteropolar binding component first having been vapour-deposited on the extremely thin layer of aluminium and then on this a dielectric layer of a material with a higher heteropolar binding component.

We have found that zircocium dioxide (approximately 67% heteropolar binding component) and silicon monoxide (approximately 51% heteropolar binding component) are especially suitable for the dielectric layer to be applied to the extremely thin layer of aluminium, whereas magnesium difluoride (approximately 86% binding component) is advantageously used for the second dielectric layer to be applied to the first dielectric layer.

The layer thickness of the aluminium is preferably from 10 to 1 5 nm, that of the zirconium dioxide is preferably from 100 to 800 nm, that of the silicon monoxide is preferably from 100 to 600 nm at that of the magnesium difluoride is preferably from 100 to 500 nm.

The vapour deposition of a conventional welding-protection filter in a high vacuum with an extremely thin layer of aluminium and, according to the present invention, upon this a dielectric double layer (for example ZrO2/MgF2 or Si0/MgF2) provides the desired high reflection in the infra-red range of from 780 to 2500 nm, a high ultra-violet stability and increased reflection in the visible range of from 380 to 780 nm, coupled with a good mechanical and corrosion resistance.

The cleaned side of a conventional welding-protection filter made of glass or sythetic resin with measurements appropriate for a welder's protective helmet is covered with an aluminium layer of about 12 nm thickness in a high vacuum vapour deposition plant at a pressure of 1.33 mPa and with a vapour deposition rate of 1 nm.s~'. Without interruption of the vapour deposition cycle, on to the aluminium layer there is first vapour deposited an approximately 550 nm thick layer of zirconium dioxide and upon this an approxiamtely 350 nm thick layer of magnesium fluoride.

Several heat-reflecting welding-protection filters thus coated according to the present invention were subjected to investigations in the laboratory and in inert gas welding operations. The results obtained are given in the following Table, For comparison, conventional welding-protection filters, commercially available welding-protection filters coated with gold and welding-protection filters coated with aluminium but without the dielectric double layer were subjected to the same investigations.

TABLE Results of investigations of glass welding-protection filters coated according to the present invention (A), commercially available (B), gold-coated and commercially available (C) and only coated with aluminium (D)

No. parameter D 1 infra-red reflection in the range A3197;;{91) of780-2500nmin% 86.2 2 reflection in visible range of 380-780 nm in % 65.2 4.0 55.2 1) 3 relative change of the degree of light transmission T after ultra-violet irradiation according to DIN 4646 part 5) in % 1.0 4.5 1.2 50.3 4 relative change of the degree of light transmission T as measure of the mechanical strength 2) in % 1.0 1.0 48.2 100.0 5 relative change of the reflection at 502 nm as a measure of corrosion resistance 3) in % 4.0 0.3 2.0 60.9 6 inherent heating up in the case of long-lasting inert gas welding in OOC. 30.0 70.0 35.0 1) Explanation of Table 1) Because of the investigational results in experiments 3, 4 and 5, which show that a weldingprotection filter which is only coated with aluminium cannot be used, investigations according to experiments 1,2 and 6 were omitted.

2. The coating of the welding-protection filter or of one side of a conventional welding-protection filter was tested for 1 minute with a rubber bung of 30 mm. diameter rotating at 500 r.p.m. under a loading of 2 kp. The measurement of the degree of light transmission took place before and after this mechanical treatment.

3. The welding-protection filters were boiled under normal conditions for 30 minutes in water, the reflection being measured before and after boiling with a leucometer (VEB Carl Zeiss Jena).

From the above investigations, it can be seen that only the welding-protection filter coated according to the present invention fulfils all of the requirements of enables equal or better results to be obtained in comparison with a coating with gold.

Thus, in the infra-red range of from 780 to 2500 nm, there is a high degree of reflection of the heat-reflecting welding-protection filter according to the present invention in continuous use.

The high reflection of the heat-reflecting welding-protection filter according to the present invention in the visible range of 380 to 780 nm permits a low-contrast observation of the welding puddle.

Because of the high ultra-violet stability, the requirements demanded of an effective eye-protection agent for carrying out welding operations is fulfilled.

The good mechanical and corrosion resistance of the heat-reflecting welding-protection filter according to the present invention ensures that the degree of protection does not change. Thus, the additional cost of protection for the coating is unnecessary.

Claims

1. A heat-reflecting welding protection filter comprising a layer of aluminium which has been vapour deposited in a high vacuum on one side of a conventional welding protection filter, wherein on to the extremely thin layer of aluminium there is vapour deposited a dielectric double-layer system, the materials of the two dielectric layers differing in their heteropolar and monopolar bonding components, a dielectric layer of a material with a lower heteropolar bonding component first having been vapour deposited on the extremely thin layer of aluminium and then on this a dielectric layer of a material with.

a higher heteropolar binding component.

2. A filter according to claim 1, wherein the dielectric layer vapour deposited on to the aluminium layer is a layer of zirconium dioxide or of silicon monoxide.

3. A filter according to claim 1 or 2, wherein the second dielectric layer is a layer of magnesium fluoride.

4. A filter according to any of the preceding claims, wherein the layer of aluminium has a thickness of 10 to 15nm.

5. Filter according to any of claims 2 to 4, wherein the zirconium dioxide layer has a thickness of 100 to 800 nm.

6. Filter according to any of claims 2 to 4, wherein the silicon monoxide layer has a thickness of 100to600nm.

7. Filter according to any of claims 3 to 6, wherein the magnesium fluoride layer has a thickness of 100 to 500 nm.

8. A heat-reflecting welding-protection filter according to claim 1, substantially as hereinbefore described and exemplified.

9. A welding helmet, whenever provided with a filter according to any of claims 1 to 8.