JPS6015699B2 - Method and apparatus for vapor deposition treatment of strip steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a belt-shaped metal substrate with a large width (280 meters);
In particular, it relates to a method and apparatus for laminating steel strips with aluminum in vacuum.

This lamination is carried out for the purpose of corrosion protection of the metal strip material.

Previously known deposition layers and methods for manipulating the same operated at substrate widths of less than 400 squares and strip speeds of less than 3 ms-1.

Heating of the evaporation crucible was done with an electron beam with a power of up to 250 KW.

The temporal average power density of the part of the evaporation crucible loaded by the electron beam is 0. The lower limit of the power density, which is W-2 to 1.2 W-2, is determined by the energy efficiency of evaporation. Power density <0. In the case of Fox W enemy-2, the rate of heat radiation of the evaporated substance is uneconomical compared to the enthalpy of evaporation utilized. The upper limit of power density is determined by the sputter limit. Power density >0. In the case of Iso W arc-2, a depression of evaporated material appears at the position where the electron beam collides. The depth of this recess increases as the power density increases. Vigorous wave motion occurs on the evaporated material.
When the power density is 1.2-2 or higher, liquid evaporated substances begin to scatter. In this case, the difference in the height of the vacuum between the location where the electron beam impinges and the portion not loaded with evaporated material is about 2 m. When the power density is within the range mentioned above, a vapor cloud with a vapor pressure in the 10-A range is formed on the evaporated material. The distance between crucibles and substrates is approximately 45 cm. If the electron beam is distributed over the evaporated material in a way that is optimal for the above-mentioned dimensions of the evaporation device, it is still possible to perform the evaporation method with relatively small layer thickness variations in the direction transverse to the substrate guide. Relatively high, about 5
A steam flow utilization of 0% results. It is known that the greater the availability of vapor flow, the greater the ratio of substrate to deposition spacing.

Therefore, in order to reach an economical radiation location, efforts are made to obtain the smallest possible deposition spacing given the width of the substrate. From this point of view, it is known to mount the evaporation crucible on a support whose height is adjustable in a suitable manner in order to adapt the evaporation interval to the particular working conditions (see East German Patent No. 113 247). ). Furthermore, the magnetic turning of the electron beam is performed by a static magnetic field of the inhomogeneity, and the radiation angle into the turning field of the inhomogeneity for electron trajectory modification is changed mechanically and/or for the electron beam. It is also known to adapt the inhomogeneities in this case by means of opposing magnetic fields existing between the radiation closure and the deflection field (see East German Patent No. 12 072). This makes it possible to keep the radius of curvature of the electron beam deflected from a horizontal direction to a vertical direction on the evaporated material to a small value compared to the width of the substrate. In this case, if the above-mentioned necessary correction caused by the inhomogeneity of the magnetic field of distortion is moderated, i.e. if the difference in the radiation angle between the central beam and the tread beam is not too large, then the spacing can be further reduced. Is possible. The combination of the two configurations described below allows for a substrate deposition spacing of 0.6 and a vapor flow utilization of about 75%.

Furthermore, it has become known to irradiate the evaporated material with an electron beam at a large angle between the direction of the crab beam radiation and the reference position of the evaporation crucible in order to reduce the evaporation spacing (GDR 121 802). reference).

This relatively oblique emission of the electron beam onto the evaporated material can reduce the efficiency of the electron beam being dissipated onto the material to be deposited and remaining absorbed by the vapor cloud. When this configuration is applied in conjunction with the various configurations described above, the deposition interval can be reduced to 0.4 of the width of the substrate. However, when the work was actually carried out, it was found that the minimum deposition interval within the above-mentioned region of steam pressure within the steam transport was not less than about 40 ships.

If this Z layer is used during deposition, the variation in layer thickness increases both transversely and longitudinally with respect to the substrate guidance direction, despite an optimal power distribution of the electron beam on the evaporated material. This variation in layer thickness cannot be related to the period of mechanical deflection of the electron beam. This variation in layer thickness Z is not periodic. The maximum and minimum values of layer thickness are 0.1s and 0.1s. Done within the time between $. This is due to the wave motion on the evaporated material, which occurs when a certain power density of the electron beam on the evaporated material is exceeded.
2 The disadvantage therefore is that it is not possible to derive any advantage from the combination of known configurations or to apply these configurations to arbitrary strip widths and strip speeds. Even if the above configuration can be used, a high utilization of steam flow can be achieved with a small deposition interval, but large variations in layer thickness will occur, or if the deposition interval is large, variations in layer thickness will occur. Although this is small, it results in low utilization of the steam flow. Reduces power density on evaporative substances,
It is easy to prevent wave motion from appearing. However, the reduction in power density is due to the length of the evaporation crucible,
This can result in the heating requiring two electron beams or two separate deposition fixtures. On the other hand, it is also possible to reduce the web speed, but this reduces the production efficiency of the deposition system. In any case, the efficiency of the evaporative energy decreases as the power density on the evaporative material decreases.

The power loss due to thermal radiation of the evaporated material, the heat conduction through the evaporation crucible, and, as already mentioned, the smaller the fraction of electrons remaining after dissipation, the greater the power density on the evaporated material. A reduction in the power density is thereby always accompanied by a reduction in the productivity of the device. The aim of the invention is to achieve a high efficiency of energy transfer and to largely eliminate the drawbacks of the known technology.

The device according to the invention is structurally simple, requires little maintenance and guarantees high productivity. The problem underlying the invention is that even when working at high power densities and when the width of the strip material is as large as 2800 feet, the layer thickness is significant both transversely and longitudinally to the direction of guidance of the substrate. The object of the present invention is to create a method and apparatus for depositing aluminum on a strip of material without fluctuations.

Steam flow is utilized to a high degree. The present invention solves the above problems by emitting an electron beam of constant power and power density into a magnetic field created by a special deflection device and deflecting it towards the evaporated material, in this case into a dense vapor cloud. By using magnetic gas concentration to prevent the generation of too large scattering loss, and by dynamically controlling the duration of the electron beam on the evaporated material, scattering due to anisotropic distortion of the electron beam flake. It becomes possible to reduce the risk of occurrence.

For this purpose, a focused electron beam is irradiated onto the surface of the evaporated material existing in the evaporation crucible by programming and irradiated at a mirror angle to the surface of the evaporated material. In this method, an electron beam with a power of about 10 KW per width of the strip material is applied to the evaporated material with an electron curvature radius of about 25 KW through an appropriate static magnetic field. An annular depression is formed by evaporation in a direction transverse to the running direction of the strip material over almost the entire width, the length of this depression corresponds to the width of the strip material and the oblique angle is between 350 and 450. The width of the evaporation crucible is divided into three, and the electron beam is 1.5 times faster than the outer regions of the three regions. 1. At the bottom of the recess. Arc W arc-2~2. Song W
−2 and the time for the electron beam to pass through the depression formed by the evaporation and the time for returning to the starting point is chosen to be 22 hs, in which case the evaporation of the electron beam The application time for each point on the surface of the crucible is <2 ms.

The power density on the vaporized material increases accordingly, without the wave motions occurring on the vapor-emitting parts of the vaporized material, which hitherto made it impossible to apply smaller deposition spacings.

The limit value of spatter generation, which was conventionally limited to the average output of 1.2 arc W skin-2, is moving in the direction of increasing.

This is because the local distribution of the power density takes place in such a way that an annular vapor pressure depression of constant shape is created. Carrying out the method according to the invention, which comprises a vacuum chamber, an evaporation crucible made of uncooled ceramic material with a crucible support, an electron radiation gun, deflection and deflection devices as well as a rocking shield and an oblique strip material guide. According to the present invention, the device for this purpose is provided with a magnetic short-circuit portion that surrounds the electron beam from all sides with a length of about 10 h to 12 h at the emission position of the electron beam.

The coil of the magnetic turning device is filled with iron and has no iron retainer. The distance between the coils is 2.
1-2. It's a needle sound. The coil is placed outside the vacuum behind a non-magnetic wall. The evaporation crucible boat has a width that is 21.2 times the width of the material strip and a length that is 0.4 times the width of the material strip. The depth of the recess is 60 to 10 degrees. The band steel is loo ~1
It is guided through the evaporation crucible at an angle of 4o and at intervals of 0.3 to 0.4 times the width of the strip material. In order to conveniently manage the apparatus, it is advantageous to mount the crucible support with the evaporating crucible, the rocking shield and the half of the deflection device on a movable door in the wall of the vacuum chamber. partially physically contradictory requirements for the magnetic turning device that arise when applying the known method steps and devices to the deposition of wide strip steel;
That is, the annular vapor pressure depression, which is equal to the area of action of the electron beam 3, must have a slight elongation in the direction of travel of the strip material and a large elongation in the direction perpendicular to this direction. At the same time, the requirement of a small radius of curvature of the electrons in order to achieve short deposition intervals is fulfilled by the device according to the invention.

Due to the large ratio of the magnetic leg spacing to the beam path in the area of the beam emission position into the deposition chamber according to the invention, a correspondingly high magnetic field strength is achieved by the magnetic short circuit surrounding the electron beam on all sides. It may be reduced in this region, but 〈 may disappear. This allows for a small radius of curvature of the electron beam to be deflected in accordance with the pole leg. This magnetic field created by the deflection position has strong inhomogeneities within the region traveled by the electron beam. As a result, so-called false replicas appear in the form of disturbances and distortions of the electron beam image on the evaporated material. Distortions are corrected by applying mechanical corrections in a known manner. Along with this, a linear annular depression is created due to the vapor pressure. Due to distortion of the electron beam flecks and scattering losses within the vapor cloud, 1. The minimum required power density of Uta W arc-2 is reduced. This decrease is 0 in advance
This is accomplished by placing the electron beam in a magnetically gas focused state within the electron gun in a known manner. From this, an electron beam with an already increased power density of approximately 2 thighs W-2 is emitted into the magnetic turning field, and the beam electrons are dispersed by collision with the radiation axis at the center due to magnetic gas concentration. Most of ■ Everything is put back again. This increases the Kameko beam's ability to penetrate dense vapor clouds. Due to the heterotropic distortion of the electron beam flecks that is significantly larger at the edge of the annular vapor pressure depression than in the central region, 2. The maximum power density of the W-Arc-2 is exceeded, which creates a risk of splashing. By controlling the duration of the electron beam according to the invention, the power density in the central region is reduced relative to the green region, although it varies along the annular vapor pressure depression. An approximately constant power density on the recess base and therefore an approximately constant depth of the recess due to the annular vapor pressure is thus obtained. The vapor pressure depression changes its shape depending on these conditions, but it is not critical. Therefore, the disappearance of the depression due to the vapor pressure, which would cause the beam to scatter, is avoided. In a loaded case, the significant difference in specific evaporation rates that occurs in the unloaded section results in most of the vapor being provided from the relatively quiet vapor pressure depression. In the above-described vapor cloud, which has a small elongation and high density, the vapor flow density distribution has a correspondingly high temporal constancy despite the small distance from the evaporated material. It can be achieved. Connected to this vapor source formed according to the invention, a substrate is provided with the minimum possible deposition spacing, but no dangerous layer thickness variations in the longitudinal and lateral direction occur. The invention will be explained in more detail below with reference to embodiments illustrated in the accompanying drawings.

In the vacuum chamber 1 (FIG. 1), an evaporation crucible 3 for aluminum is provided on a crucible support 2.

Through the vacuum chamber 1, a strip 4 to be deposited with a width of approximately 80 mm is guided at an angle Q of 1 and at a distance hv of 250 bars above the evaporation crucible 3. Evaporated material 6 (aluminum) is evaporated by the electron beam 5 with an output of 600 KW and a power density of 1 W arc-2. In this case, the output is a mechanical deflection device 7 with a frequency of 3 squares 2, transverse to the running direction of the strip and per arc of width of the strip W~1
The output of the dish W is distributed to effect. The distribution of the power in the longitudinal direction with respect to the running direction of the strip-like Z material is carried out by the application of a turning device 8, which will be described below, and by the action of the electron beam 5 in the gas-concentrated state. The action of the electron beam is ensured by an automatic control valve 9, which maintains the pressure in the middle part Z of the electron gun 10 at approximately 0.7 Pa. A programmed control of the power distribution in the mechanical deflection device 7 over the entire width of the evaporation crucible is carried out on the evaporated substance 6 by means of a magnetic deflection device 8 . The magnet system of the deflection device 8 has a pole leg spacing of 200 mm. Both iron-filled coils have no retainers and are located outside the vacuum behind a non-magnetic wall. The diameter of the iron core is 19 mm, and the length is 58 mm. The distance from the emission position of the electron beam 6 to the working position on the evaporated material 6 is approximately 1'3 of the magnetic pole leg spacing. A magnetic short-circuit portion 11 having a length of 120 ribs exists at the radiation position of the electron beam 5. This dimension requires only a short mechanical modification from the central beam 5a to the edge beam 5b, which modification only slightly increases the required deposition spacing. electron beam 5
falls into the annular vapor pressure depression 12 created by this beam at an angle of approximately 3 pi. The power distribution within the longitudinal direction of the strip material guide obtained by the above measures has a maximum value of about 2 trillion W-2 in the center of the electron beam action and drops to zero towards the green area. This descent is
Oblique angle. This is done in such a way that a vapor pressure depression 12 with =30° to 40° is automatically created (FIG. 2).
The distance to the steel strip 4 can be changed by means of the crucible support 2 in order to activate the swinging shield 13 for interrupting the deposition operation. The evaporation crucible 3, the crucible support 2, the rocking shield 13 and the coils of the magnetic system of the deflection device 8 are located next to the movable wall 14 of the vacuum chamber 1. This movable wall 14 is connected to a traveling frame 15 . BRIEF DESCRIPTION OF THE DRAWINGS: FIG. 1 is a cross-sectional view of the vapor deposition layer along the running direction of the strip material, and FIG. 2 is a plan view and side cross-section of an evaporation crucible with depressions due to vapor pressure in the method according to the invention. FIG. 3 is a partial view of a deposition path combined with a movable wall.

The symbols in the figure are 3... Evaporation crucible, 4... Steel strip, 5... Electron beam, 7... Mechanical deflection system, 8... ... Turning device, 14...
・Non-magnetic wall.

Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] 1. Aluminum is made into a steel strip by controlling the surface of an evaporated material existing in an evaporation crucible with a focused electron beam and irradiating it obliquely to the surface of the evaporated material. In the vapor deposition method, an electron beam with an output power of 5 KW to 10 KW per 1 cm of the width of the strip material is applied to the evaporated material through an appropriate static magnetic field with a radius of electron curvature of about 250 mm to a width approximately corresponding to the width of the strip material. Over the entire area, an annular depression is formed by evaporation transversely to the running direction of the strip material, the length of this depression corresponds to the width of the strip material and has an inclination angle of 35° to 45° and a constant The width of the evaporation crucible is divided into three, and the electron beam is applied at a rate of 1.5 times that of the outer regions of the three regions, and the concavity formed by evaporation is 1.5KWcm^-^2~2.5 at the bottom of
The time for the electron beam to pass through the depression formed by evaporation and the time for return to the starting point is selected to be ≧20 ms, in which case the electron beam A method as described above, characterized in that the beam is applied to each point of the surface of the evaporation crucible for a duration of <2 ms. 2. A vacuum chamber, an evaporation crucible made of uncooled ceramic material on a crucible support, a deflection device, a deflection device for mechanically deflecting the electron beam, and a deflection device for dynamically correcting the distortion of the deflection device by magnetic force. An apparatus for carrying out a method for vapor deposition processing of steel strips, consisting of a magnetic deflection device, an oscillating shield and an inclined strip material guide, in which the electron beam 5 in the radiation position has a length of 100 to 1
It is surrounded on all sides by a 20 mm magnetic short circuit 11, the magnetic deflection device 8 is filled with iron and has no retainer, and has a width of 2.1 to 2.6 times the width of the strip material. The evaporation crucible is arranged at mutual spacing outside the vacuum behind the non-magnetic wall 14, with a width of ≧1.2 times the width of the strip material and ≧0.
．． 4 times the length and a crater bath depth of 60 to 100 mm, and that the strip 4 is at an angle of 10° to 14° and at intervals of 0.3 to 0.4 of the width of the strip material. The above device, characterized in that it is provided above the evaporation crucible 3. 3. The crucible support 2 with the evaporation crucible 3, the rocking shield 13 and the half of the deflection device 8 are mounted on a movable wall 14 as a door of the vacuum chamber 1. The device according to item 2.