DD200897A1 - METHOD AND DEVICE FOR SUBSTITUTING AL-EVAPORATORS - Google Patents

Abstract

The invention relates to a method and the associated device for Nachbeschickung AI evaporators for continuously operating vapor deposition. The aim of the invention is to reduce rejects and improve material and energy economy. The task is to supply the material without interrupting the sputtering process. According to the invention, the Al is melted in a Vorschmelzkammer with the electron beam and heated in a crucible and degassed. Then it is metered via a cascade-shaped channel system the Verdampffertiegel zugefuehrt. The entire process runs in a vacuum.

Description

Method and device for refilling Al evaporators

Applicable to the invention _i

The process for the re-feeding of evaporating material serves the metered re-feeding of aluminum in high-rate continuous evaporation devices for coating preferably moving belt-shaped metallic substrates »

Characteristics of the known technical solutions

The known steaming systems operate on the principle that in the evaporation break the crucible is replenished with evaporating material by aluminum wire or pieces are guided in the crucible and melted there. This refilling of the "Al in the vaporizer crucible during evaporation, whether from above directly to the surface of the material to be vaporized or through the crucible below the surface _s leads to impairment of the evaporation process (DD-PS 59 981)» This defect is due to this in that the gas dissolved in the Al is partially released during melting in vacuum and partly when the Al melt is heated to an evaporation temperature of about 1850 K. This gas leads to an increase in pressure in the entire steaming station A reduction in the adhesion of the layer and a gray coloration of the layer Layer surface are the result · Another undesirable phenomenon is caused by non-directional flows of the vaporized material in the evaporator crucible,

caused by the just molten and still relatively cold Al, caused «The resulting non-uniform and time-varying temperature distribution of the vapor-emitting surface leads to layer thickness variations in Quer ™ and longitudinal direction of the band to be vaporized _β

It is also known that the evaporation vessel is the evaporator vessel. to feed in liquid form via pipelines and. This is melted outside the vacuum in an oven and kept liquid (DE-OS 1 938 992), Here, the evaporant is introduced below the surface of the evaporator This method has the disadvantage that the molten in the furnace vessel Al is not completely degassed and thus this into the evaporator crucible and the gas leaving the melt causes the already mentioned disturbances <>

Aim of the invention

The object of the invention is to Evaporate, in particular Al, the evaporator crucible so that the disadvantages described are avoided and a continuous operation steaming of bands of large widths (^ 500 mm) is possible "The device is with respect to energy and Al Consumption, work economically,

Presentation of the essence, the invention

The invention has for its object to provide a method and the associated device for Nachbeschickung of Al evaporators, which causes only a small gas attack in the Bedampfungsstation, barely changed the temperature distribution on the surface of the evaporating material and allows a metered Nachbeschickung of Al «Der Bedampfungsprozeß should be influenced neither by the Nachbeschickung still by accumulating oxide layers _β

According to the invention the object is achieved in that the Al is liquefied outside the stoving station under vacuum in a separate crucible by means of electron beam and heated only to ca * 1000 K and the liquid Al is passed from the crucible in the evaporator crucible located within the vaporization station via a cascade system, the entire process is carried out in a vacuum. "For economical reasons, the vaporization material is fed as a billet, which is melted by the electron beam and dripped into the crucible." The molten bath is likewise exposed to the electron beam. "Pur This liquefaction and heating of the Al in the crucible and the A specially controlled electron beam is used to meter the outlet into the cascade system, and the control is such that the residence time of the electron beam on the ingot and on the crucible, depending on the required power for melting and heating ο The exchange of the electron beam between the ingot and the crucible takes place in a few 10 milliseconds «In periods _? However, the electron beam is focused on the crucible outlet _β This leads to a local overheating of the Al and Al ^ Oo in this area, so that it breaks through the liquid Al. comes through the oxide layer at already very small peaks of the level "The case low outflowing amount of Al causes the Al is completely degassed in the cascade system based on the reasonable vacuum surfaces ratio ₉ The control a metered" tapping "is done by the Controlling the electron beam "The entrained portion of AIpOo does not interfere with the evaporation process. To prevent the Al from splattering and increasing pressure in the connected evaporation station, the residual gasification of the Al melt takes place by so-called" aluminum foaming " _o With this form of material supply If large quantities of AIpO. are introduced into the system during melting, this oxide deposits on the surface of the molten bath. When heating the molten bath to only 1000 K, this layer is not destroyed ₀ This has the advantage that the already present at these temperatures evaporation of Al is reduced to uncritical values *

The device for carrying out the method consists of a vacuum chamber, in which the Al is introduced via a lock in the form of ingots. In this vacuum chamber, called Vorschmelzkammer, a tiltable crucible is arranged so that the molten material drips in ₀ A spout is attached to the crucible At the Vorschmelzkammer an electron gun is arranged so that the electron beam can act on the solid Verdampfungsgutj the melt and the outlet «Below the outlet, at a small distance, there is a channel system (cascade), which is interrupted so that the effluent evaporating a short Route in freefall. The last trough is also spaced from the evaporator crucible and is adjustable as the vaporizer crucible can be adjusted in height. The 'height' of the free Palis in the entire cascade system is at least 100 mm in each case. The Vorschmelzkammer is vacuum-connected to the Bedampfungsstation, it being expedient to decouple both vakuummäßig »In this case, the channel located in the region of the valve is to be run,

Furthermore, is it expedient to heat-resistant the gutter system _? only insignificantly gassing in a vacuum and Al-resistant material, preferably silicon carbide (SiG)

embodiment

In the accompanying drawing show;

Fig. 1: a section through the pre-melt chamber,

FIG. 2: a top view of the pre-melt chamber and vaporization station, FIG.

In the Vorschmelzkammer.1 is the crucible 2 ₅ in which the Al-ingot 3 is melted by means of the electron beam generated in the electron gun 4 5 The electron beam 5 is applied to the Al-mass 3 _S the crucible 2 and the Schme.fztiegel 2 located Outlet G ₉ The

Crucible 2 is tiltable. When tilting the crucible 2, the liquid Al flows through the outlet 6 in the inclined channel 7 »from there through a vertical tube 8 in the also inclined channel S? from the ea then. in the evaporating crucible 10 passes, which is in the actual Bedampfungsstation 11 «It falls the liquid Al in the cascading gutter system part of the route in free fall. This leads to "foaming" of the Al and thus to residual degassing. The channel 7 is movably arranged, if at this point a valve for vacuum decoupling is arranged in the vacuum section. Since the evaporator crucible 10 is adjustable in height, the channel 9 is firmly connected to it * thus the drop height from the channel 9 in the evaporator crucible 10 is constant. In order to prevent this, the drop height between the grooves 7 and 9 is impractically large »is the tube 8 disposed therebetween, creating an additional cascade,

The electron beam 5 for melting and heating the Al is controlled so as to be deflected periodically in the range of several seconds focused on the outlet 6 of the crucible 2, resulting in a local overheating of Al and Al ₂ Oo in this area

Claims (2)

invention claim 1 * A method for Nachverickung of Al evaporators by the vaporized material is melted outside the Bedampfungsstation and fed in the liquid state, characterized in that the Al is melted by means of controlled electron beam in a vacuum and heated in a crucible to about «1000 K and off metered into the crucible through the electron beam via cascades in a vacuum into the evaporation crucible in the vaporization station » 2. Device for carrying out the method according to item 1, consisting of a associated with the Bedampfststation Vorschmelzkammer, characterized in that the Vorschmelzkammer (1) is vacuum-connected to the Bedampfungsstation (11) that in the Vorschmelzkammer (1) via a lock introduced Al ingots (3), a tiltable crucible (2) with outlet (6) and an electron gun (4) with the evaporating material, the molten bath and the outlet (6) can be acted upon electron beam (5) are arranged that below the outlet ( 6) beginning .und above the evaporator crucible (10) of the steamer station (11) endend grooves (7; 9) are arranged, which are interrupted at least at one point by a fall distancej and that the fall distance and the distance between the channel (7) and the outlet (6) and the evaporator crucible (10) are each at least 100 mm o Device according to point 2, characterized in that between the steaming station (11) and the pre-melt chamber (1) a valve is arranged and in this area the channel (7) is movable _o 4 «device according to point 2, characterized in that the grooves (7; 9) of heat-resistant, in the vacuum hardly gassing and Al-resistant material preferably silicon carbide, consist» For this 1 page drawings