JPS6327425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A method for the recharging of evaporates is particularly suitable for metered recharging of aluminum in continuously operating high rate evaporators for stacking of moving strip metal substrates. used.

The known evaporator works on the principle that an aluminum wire or piece is introduced into a crucible and melted there, so that during the evaporation pause the crucible is refilled with evaporated material. This refilling of Al into the evaporator crucible while evaporation is taking place is
Whether at the surface of the substance to be evaporated directly from above or through a crucible below the surface, this results in a disturbance of the evaporation process. (German Democratic Republic Patent No. 59981). This defect arises because the gas liberated in the Al is partly liberated during melting in vacuum and partly during heating of the Al melt to an evaporation temperature of about 1850 K. This gas causes a pressure increase across the evaporation station. The result is a decrease in the adhesion of the layer and a graying of the layer surface.
Further, undesirable phenomena are constrained by the freshly melted and still relatively cool Al.
Caused by the non-directional flow of evaporate within the evaporator crucible. The resulting uneven and time-varying temperature distribution on the vapor release surface leads to variations in the lateral and longitudinal layer thickness of the zone to be evaporated.

It is also known (German Published Application No. 193 89 992) to supply the evaporation vessel with liquid evaporate through a conduit, which is melted in a furnace outside the vacuum and kept in liquid form. The vapor is then brought below the surface of the evaporator. This method has the disadvantage that the Al melted in the furnace vessel is not completely degassed, so that it reaches the evaporation vessel and the gases evolved from the melt cause the disturbances already mentioned. Motsu.

The object of the present invention is to improve evaporates, especially Al, with a wide range (>
500 mm) band to be additionally fed to the evaporator crucible.

The problem of creating a method for the supplementary feeding of an Al evaporator and a device for carrying out this method forms the basis of the present invention, which method causes only a slight gas evolution in the evaporation station and the surface of the evaporator. The temperature distribution changes little and also allows metered additional feeding of Al. The evaporation process is not influenced by additional feeds or by the oxide layer generated.

According to the present invention, this problem is solved by the fact that Al is liquefied outside the evaporation station using an electron beam in a separate crucible in vacuum and only heated to about 1000 m The solution is that the evaporator crucible in the evaporator crucible is introduced via a cascade device, the entire treatment being carried out under vacuum. For economical reasons, the evaporate is supplied as sea cucumber pig iron, which is completely melted by the electron beam and dripped into the crucible. The molten pool is likewise irradiated with an electron beam. A specially controlled electron beam is used for this liquefaction, heating of the Al in the crucible and metering of the effluent to the cascade device. Control is achieved in such a way that the residence time of the electron beam on the sea cucumber iron and crucible is adjusted in response to the required melting and heating performance. The exchange of electron beams between the sea cucumber pig irons and crucibles takes place in a few tens of milliseconds. However, for periods whose length is in the range of a few seconds, the electron beam is focused at the crucible outlet. This means that Al in this region
This leads to local overheating of Al ₂ O ₃ , so even if the limit is exceeded only slightly, the oxide layer is already broken and a liquid state is formed.
Al will stand out. The small amount of Al that flows out in this case serves to ensure that the Al in the cascade device is completely degassed based on the correct vacuum surface ratio. Control of the metered "boiling" is performed by electron beam control. The induced precipitation part of Al ₂ O ₃ does not interfere with the evaporation process. Gasification of the remainder of the aluminum melt continues by a so-called "aluminum bubble" to prevent Al blow-out and pressure build-up in the connected evaporation station. In this form of material supply, a large amount of Al ₂ O ₃ is still charged into the device during melting. This oxide is deposited on the surface of the weld pool. Heating the molten pool to 1000K does not destroy this layer. It has the advantage that the evaporation of Al already present at this temperature is reduced to non-hazardous values. The apparatus for carrying out this method consists of a single vacuum chamber, into which Al in the form of sea cucumber piglet is introduced through a gate. In this vacuum chamber, called the pre-melting chamber, a swingable crucible is placed.
It is arranged so that the substance of the molten component drips into it.
The crucible is equipped with an outlet. An electron gun is arranged in the pre-melting chamber so that the electron beam can irradiate the solid evaporated material, the molten pool and the outlet. On the underside of the crucible 2 there is an outlet 6 for the melted and flowing material. Above the crucible, the Al sea cucumber piglet 3 is melted and the first degassing takes place already. The molten flow material flows into conduit 7 and into conduit 9
It falls into the evaporator crucible 10. Between conduits 7 and 9 is a tube 8 through which the flowing molten material passes. It is recommended that there be a distance of at least 100 mm between the tubes 7 and 9 to allow for degassing (foaming). Furthermore, it is appropriate for the conduit device to be heat-resistant, emit little gas under vacuum, and to be made of Al-resistant material, in particular silicon carbide (SiC).

There is a crucible 2 in the pre-melting chamber 1, and in it
Al sea cucumber piggy bank 3 is melted by an electron beam 5 produced by an electron gun 4. The electron beam 5 irradiates the Al sea cucumber piglet 3, the crucible 2, and the outlet 6 of the crucible 2. The crucible 2 is tiltable. When the crucible 2 is tilted, the liquid Al flows through the outlet 6 into the inclined conduit 7 and from there through the vertical tube 8 into the also inclined conduit 9, from where it then reaches the evaporator crucible 10. , the evaporator crucible is located in the original evaporation station. At this time, the liquid Al in the cascade-type conduit device falls into a part of the arbitrary falling section. By doing so, "bubbling" of Al and the resulting removal of residual gas occur.

The tube 9 rests on the evaporator crucible 10 and has at its other end a rotational bearing point to follow the movement of the evaporator crucible 10 as it is raised and lowered. The distance between the outlets from the tube 9 is thus always kept constant.

The premelting chamber 1 can be connected in vacuum to the evaporation station 11 via a connection in the region of each tube. That is, both the pre-melting chamber and the evaporation station constitute a uniform pressure exhaust bell.
However, it is advisable to provide a vacuum valve in the area of the outlet 6 to release the connection. The outlet 6 thus projects from this vacuum valve and retracts when the valve is closed. That is, the tube 6 is previously withdrawn into the pre-melting chamber in order to close the valve. In order to thereby avoid an unduly large fall height between the conduits 7 and 9, the conduit 8 is arranged between them, thereby creating an auxiliary cascade.

The electron beam 5 for melting and heating the Al is periodically deflected to focus on the outlet 6 of the crucible 2 over a period of several seconds, leading to local heating of the Al and Al ₂ O ₃ in this region.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the pre-melting chamber, and FIG. 2 is a plan view of the evaporation station of the pre-melting chamber. 1... Preliminary melting chamber, 2... Crucible, 3... Al
Sea cucumber pig iron, 5...electron beam, 6...outlet,
7,9... Conduit, 10... Evaporator crucible, 11...
...Evaporation station.

Claims (1)

[Claims] 1. Al is melted in a vacuum by a controlled electron beam, heated to 1000℃ in a crucible, and transferred from the crucible to an evaporator crucible by an electron beam through a cascade in a vacuum to an evaporator crucible. A method for refilling an Al evaporator, characterized in that the evaporated material is melted outside the evaporation station and supplied in liquid form. 2 The pre-melting chamber 1 is connected to the evaporation station 11 in a vacuum manner, and into the pre-melting chamber 1 there is Al sea cucumber pig iron 3 introduced through the gate and an outlet 6.
A tiltable crucible 2 with An evaporation station characterized in that terminating conduits 7; 9 are arranged, and between these conduits 7; 9 there is a vertical conduit 8, with a separation of at least 100 mm between conduits 7 and 9. A device consisting of a pre-melting chamber connected to a 3. Device according to claim 2, characterized in that a valve is arranged between the evaporation station 11 and the pre-melting chamber 1, in which the conduit 7 is movable. 4. Device according to claim 2, in which the conduits 7; 9 are made of a heat-resistant, virtually gas-free in vacuum and aluminum resistive material, in particular silicon carbide.