MXPA98002076A - Materials of magnetic armor, method to produce them and pipe of image in colors produced by incorporating the matters - Google Patents

Abstract

Magnetic shielding materials used in color image tubes are provided which have excellent internal magnetic shielding characteristics and excellent handling resistance, a method of producing the materials in color image tubes, produced by incorporating the materials. The magnetic shielding materials produced by subjecting hot-rolled steel strips to the bottom consists essentially of an amount equal to or less than 0.006% by weight of C, equal to or less than 0.002% by weight of N, equal to or less than 0.5% by weight. weight of Mn, 0.5-2.5% by weight of Si, the rest of Fe and impurities unavoidable when cold rolling and subsequently annealing the cold-rolled steel strip at a temperature of 500-700øC, and applying a nickel coating to the same after the harvest

Description

OF MACISIETAL SHIELDING. METHOD TO PRODUCE THE SAME AND IMAGE TUBE IN COLORS PRODUCED BY INCORPORATING THE TRFTFTTrFS FIELD OF THE TECHNIQUE The present invention relates to magnetic shielding materials used in color image tubes, a method for producing materials and image tubes in colors that incorporate the materials, and more particularly, magnetic shielding materials used in image tubes in colors, a method of production of the materials and color image tubes that incorporate the materials which show an improved handling resistance.

BACKGROUND A color image tube such as a kinescope used in a color television set substantially comprises an electron gun and a fluorescent surface which converts the electron beams into an image. The interior of the kinescope is covered with magnetic shielding materials to prevent the electron beams from being deflected by the earth's magnetism.

As such magnetic shielding materials, thin steel sheets are used on which a support treatment or a nickel coating is provided, where thin sheets of steel are formed into the desired shape by bending them and sealed to Braun tubes. a temperature of about 600 ° C The steel sheets which are used as the magnetic shielding materials are required to meet favorable mechanical characteristics such as a favorable forming capacity which includes bending and a handling resistance capable of preventing the deformation of the steel. the workpieces at the moment of transporting the magnetic shielding materials before or after the operation formation as well as at the time of stacking the work pieces in addition to presenting excellent magnetic shielding properties such as high permeability, low coercive force and High shielding efficiency To decrease the force coerci While the permeability is increased, the presence of carnivor, nitrogen, carbide or nitride precipitation in steels should be minimized, which prevents the movement of a ferromagnetic domain wall, and grain growth should be promoted while decreasing the limit grain. Although the reduction of carbon and nitrogen in the steels while increasing the grain growth of the steels provides an improvement in the information capacity since the resistance of steels decreases, at the moment of transporting the steel sheets or work pieces which are produced by bending, tend to suffer irregularities even when a light impact is applied to them, or the work pieces tend to deform due to the weight of the stacked work pieces. Although the handling resistance of the steel sheets can be improved by refining the grain or by adding a certain amount of carbon and nitrogen in the steels so as to precipitate carbide and nitride in the sheets, such method causes deterioration of the magnetic characteristics . In this way, the steel sheets used as the magnetic shielding materials must simultaneously satisfy the excellent magnetic characteristics and the favorable handling resistance, features which are in opposition to each other. Conventionally, proposals have been made of mild magnetic silicon steel sheets that have excellent handling resistance to the extent that the materials have exhibited magnetic shielding characteristics. However, such steel sheets have not been of practical use since it is difficult to apply a necessary black treatment required by the color picture tubes for the soft magnetic silicon steel sheets. To date, with regard to magnetic shielding materials, steel sheets deoxidized with aluminum, carbon black with a darkening treatment and steel sheets coated with nickel have been used in a practical way., provided with a nickel coating layer. Although these steel sheets have excellent magnetic shielding characteristics, they do not have sufficient handling resistance. Accordingly, it is an object of the present invention to provide magnetic shielding materials having excellent internal magnetic shielding characteristics and excellent resistance to handling, and a method of producing such materials and color image tubes incorporating such magnetic shielding materials. .

DESCRIPTION OF THE INVENTION The magnetic shielding materials according to the present invention are produced by subjecting hot-rolled low carbon steel strips, which essentially consist of amounts equal to or less than 0.006% by weight of C, equal to or less than 0.002. % by weight of N, equal to or less than 0.5% by weight of Mn, 0.5-2.5% by weight of Si, the rest of Fe and unavoidable impurities in the cold rolling process, annealing of the cold rolled steel strip at a temperature of 500-700 ° C and proportion of a nickel coating thereto after annealing.

BEST MODE DK CARRY OUT THE INVENTION According to the present invention, it is found that with an addition T If to hyper-carbon steels, the tensile strength of hyper-carbon steels can be handled equal to or greater than 40 g / mrrr , while the coercive force of it remains equal to or less than 1.2 oersted so the magnetic olmdaje materials used in the image tubes in odors have excellent magnetic characteristics and excellent handling resistance at the time they are obtained. The present invention is described in detail below in view of the following embodiment. The ultra-low carbon steels used as the magnetic shielding materials used in the color image tubes according to the present invention are preferably produced by subjecting the steels to decarburization and denitrification by vacuum degassing so as to decrease the carbide and mtride. pn the steels and then submit the steels to hot rolling and continuous annealing to promote grain growth in the steels. In addition, since the carbide and nitride, which are finely dispersed in the steels, prevent the movement of a ferromagnetic domain wall, therefore deteriorating the magnetic characteristics, the elements which should be included in the steels should be preliminarily restricted and the amount of addition of them so that it is as small as possible. First, the reason for restricting the kinds of elements included in the steels and the amount of addition of these elements is explained. As regards C, in the case where a quantity of C in the cold-rolled steel sheets is abundant, the carbide and the steels are increased so that the movement of the ferromagnetic domain wall is prevented while It damages grain growth. Therefore, it becomes difficult to decrease the coercive force of steels. Consequently, the upper limit of the amount of C should be 0.006% by weight. The lower limit of the amount of C should be as low as possible under the condition that vacuum degassing can be effectively carried out. With respect to N, in the case where aluminum-deoxidized steels are used as the magnetic shielding materials of the present invention, N reacts with the aluminum in the solid-solution state in the steel to form fine AlN which deteriorates the magnetic characteristics. Accordingly, the amount of N must be equal to or less than 0.002% by weight. As for Mn, the addition of Mn is necessary since Mn joins S on steel and sets S on steel as MnS to avoid hot shortening. However, since corresponding to the decrease in the amount of Mn, the magnetic characteristics increase, the amount of Mn must be equal to or less than 0.5% by weight.

As regards Si, which corresponds to the increase in the amount of Si, the coercive force is decreased and the characteristics of magnetic shielding are improved. However, the elongation decreases and the force at the tension is increased so that the training capacity is decreased. Although it depends on the heat treatments which can be carried out after the cold rolling, with an amount not less than 0.5% by weight of Si, the magnetic shielding and handling resistance characteristics required for the present invention can be obtained, while with the amount of more than 2.5% by weight of Si, the working capacity and the forming capacity are impaired. Consequently, the upper limit of the amount of Si should be 2.5% by weight. The production processes of thin steel sheets which can be used as magnetic shielding materials are explained below. First, the hot-rolled carbon strips with the above-mentioned chemical compositions, which are produced by means of vacuum refining or vacuum degassing, are subjected to deoxidation so that an oxide film produced during the process is removed. The hot rolling process. Subsequently, the hot-rolled steel strips are cold rolled at a speed equal to or greater than 70% so as to constitute the thickness of the steel strips of 0.15-0.25 mm. With a cold rolling speed of less than 70%, when the steel strips are annealed after cold rolling, the tensile strength of the strips becomes less than 40 kg / mm2, so that the handling resistance required by the present invention. Preferably, the annealing is carried out at a temperature of 500-700 ° C for 3 minutes-5 hours, based on the required strength. When the annealing temperature is less than 500 ° C, the steel strips do not soften sufficiently so that the working capacity of the steel strips impoverishes. However, with a smaller amount of Si, when the annealing temperature is high, the tensile strength required by the present invention can not be obtained. Furthermore, even with a sufficient amount of Si, when the annealing temperature exceeds 700 ° C, the tensile strength which is equal to or greater than 40 kg / mm2 required for the present invention can not be obtained, even with a period of heating of less than 3 minutes. Preferably, the annealing should be carried out at a temperature of 550-650 ° C for 5 minutes-2 hours in correspondence with the amount of Si. The annealing method can be an annealing in a box or a continuous annealing, based on the heating temperature and the heating time. After carrying out the annealing mentioned above, the steel sheets are subjected to electrocleaning for the removal of grease and deoxidation in dilute sulfuric acid so that they return to the surface of clean and activated steel sheets. Subsequently, a nickel coating is applied to the steel sheets making use of a nickel coating bath such as a Watt bath, a nickel chloride bath, a bath of sulfuric acid which is commonly used in the coating technique with nickel. It is preferable to increase the amount of coating to satisfy the corrosion resistance, but a smaller amount of coating may be necessary from the economic point of view. Therefore, the lower limit of the amount of nickel coating is 0.1 μm and the upper limit thereof is 5.0 μm.

(Example) The present invention is further explained in detail in view of the following example. Seven grades of steel A, B, C, D, E, F and G are prepared, respectively, which have chemical compositions shown in table 1, in the form of plates by vacuum degassing and then subjected to hot rolling to produce hot-rolled steel sheets that have a thickness of 1.8 mm. These hot-rolled steel sheets are deoxidized in sulfuric acid and then cold-rolled to produce cold-rolled steel sheets having a thickness of 0.15 mm. The cold-rolled steel sheets are subjected to continuous annealing under 15 kinds of conditions shown in tables 2-3 to produce substrates for coating. These substrates for coating are subjected to electrocleaning with alkali for the removal of grease and are subjected to deoxidation in sulfuric acid. After deoxidation, a nickel coating having a thickness of approximately 1.3 μm is applied to the respective substrates using a Watt bath having a usual bath composition. The coercive force of the annealed samples produced in the aforementioned manner is measured such that a first coil and a second coil are wound around the samples and a magnetic field of 10 oersted is applied to the samples. The tensile strength of steel sheets coated with nickel is measured by TENSILON. The measured results are shown in tables 2-3.

It is understood that the magnetic shielding materials according to the present invention have a lower coercive force, and at the same time a higher tensile strength so that the materials are preferably used as magnetic shielding materials used in color picture tubes. . In contrast, the example Al and A-2 comparatives fail to obtain sufficient magnetic shielding characteristics and sufficient tensile strength, although the example Gl and G-2 comparatively show an excessively high tensile strength in comparison with the resistance at the tension necessary for the present invention, they have little capacity for formation. Due to the excellent magnetic characteristics and handling resistance, the magnetic shielding materials of the present invention can be used not only as inner shielding materials of color picture tubes, but also as frame materials which are interposed between the materials of interior shielding and shadow mask materials so that they securely fix them to the panels. The sample codes (alphabetic-numerical) in Tables 2 and 3 indicate magnetic shielding materials produced by using material classes (left portion of the material codes) shown in Table 1 and variable conditions (right portion of the code numbers). material) .

Table 1 Table 2 Table 3 Industrial Applicability The magnetic shielding materials according to the present invention are magnetic shielding materials used in color image tube which are produced by subjecting a strip of steel to the low hot rolled carbon consisting essentially of an amount equal to or less than 0.006. % by weight of C, equal to or less than 0.002% by weight of N, equal to or less than 0.5% by weight of Mn, 0.5-2.5% by weight of Si, the rest of Fe and unavoidable impurities when cold rolling and annealing of the cold rolled steel strip at a temperature of 500-700 ° C, and apply a nickel coating to it after annealing. The materials have a low coercive force and excellent magnetic shielding characteristics and a high handling resistance so that the materials are preferably used as magnetic shielding materials used in color image tubes. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following:

Claims (3)

1. Magnetic shielding materials used in color image tube produced by subjecting hot-rolled low carbon steel strips, consisting essentially of an amount equal to or less than 0.006% by weight of C, equal to or less than 0.002% by weight of N, equal to or less than 0.5% by weight of Mn, 0.5-2.5% by weight of Si, the rest of Fe and unavoidable impurities to the cold rolling and annealing of the cold-rolled steel strip at a temperature of 500-700 ° C, and apply a nickel coating to it after annealing.

2. A method for producing magnetic shielding materials used in color image tubes characterized in that it comprises subjecting the steel strips to the low hot rolled carbon consisting essentially of an amount equal to or less than 0.006% by weight of C, equal to or less than 0.002% by weight of N, equal to or less than 0.5% by weight of Mn, 0.5-2.5% by weight of Si, the rest of Fe and unavoidable impurities to the cold rolling and annealing of the cold-rolled steel strip at a temperature of 500-700 ° C, and apply a nickel coating to it after annealing.

3. Color image tubes incorporating the magnetic shielding materials which are produced by subjecting the steel strips to the low hot rolled carbon consisting essentially of an amount equal to or less than 0.006% by weight of C, equal to or less than 0.002. % by weight of N, equal to or less than 0.5% by weight of Mn, 0.5-2.5% by weight of Si, the rest of Fe and impurities unavoidable when cold rolling, subsequently annealing the steel strip cold rolled at a temperature 500-700 ° C, and apply a nickel coating to it after annealing.