KR0140835B1 - Manufacturing method of al-cr alloy deposited steel sheet by single source - Google Patents

Abstract

The present invention relates to a method for producing an aluminum-chromium alloy deposited steel sheet excellent in corrosion resistance produced by a single evaporation source.

In the method of depositing an alloy layer of two metals on a steel sheet by a vacuum deposition method, when two evaporation sources are used, the alloy composition distribution of the deposition layer is distributed in an irregular and highly undulating composition, so that the deposition layer is not dense and corrosion resistance There is a problem with this falling.

In the method of manufacturing an aluminum-chromium alloy plated steel sheet, aluminum and chromium are alloy compositions of chromium content of 1.8 to 11% by weight, and are put in one evaporation source, and they are simultaneously irradiated with an electron beam and heated to evaporate to a substrate temperature of 200 to 300 ° C. Of aluminum-chromium alloy plated deposited steel sheet by vacuum deposition of an aluminum-chromium alloy plated layer in an ion plating method using a voltage of 100 to 1000 V applied to an aluminum-chromium alloy plated layer in a range of 10 to 20 g / m ² . When the steel sheet is manufactured by the method, surface smoothness and corrosion resistance are better than those of using two evaporation sources.

Description

Manufacturing method of aluminum-chromium alloy deposited plated steel sheet by single evaporation source

1 is a chart in which the depth component distribution of an aluminum-chromium alloy film containing 5.5% by weight of chromium prepared by the method of the present invention is analyzed using an Ohze electron spectrometer.

FIG. 2 is a chart of depth component distribution of an aluminum-chromium alloy film containing 5.5 wt% chromium prepared by evaporating aluminum and chromium separately from two evaporation sources using an Auger electron spectrometer.

3 is a chart showing the initial blue-green generation time when the salt spray test using a 5% NaCl solution of the aluminum-chromium alloy film according to the chromium weight% prepared by the method of the present invention

The present invention relates to a method for producing an aluminum-chromium alloy deposited plated steel sheet excellent in corrosion resistance produced by a single evaporation source. Although galvanized steel is widely used in terms of economics and productivity as a plating system for corrosion resistant steel sheets widely used as an important industrial material for automobiles, home appliances, building materials, etc., it is increasingly necessary to keep pace with diversification and detailed functionalization of industries. Quality requirements are also shifting towards higher corrosion resistance, higher heat resistance, and higher applicability of steel sheets and applicability in harsh environments. In addition to zinc, the most versatile plating system includes aluminum that is easy to secure resources, inexpensive, and satisfies mass productivity and plating performance. In general, aluminum is coated by a hot dip plating method, a spraying method, some electroplating methods, a vacuum plating method, or the like. In recent years, in order to secure high corrosion resistance, heat resistance and economical efficiency in accordance with the requirements of the demand price, hot-dip alloy plating of Al-Zn, Al-Zn-Si, Al-Zn-Mg, Al-Zn-Sn, etc. In addition, the development of aluminum-based alloy plating products such as Al-Ti, Al-Pb, Al-Sn, and Al-Ni, including amorphous Al-Mn by the electroplating method, is actively underway.

However, the hot-dip plating method does not uniformly control the adhesion amount (especially thin coating of 20g / m ² or less) and the thickness of the coating in the width direction is not uniform, and the melting point is lower than the recrystallization temperature of iron or belongs to the alloy region on the state diagram. The constraint is that it must be metal. In general, the electroplating method has a limitation of the plating metal, which is a problem of the solubility of the metal in the electrolytic solution and the electrolytic precipitation efficiency when the alloy plating in the industrial equipment. In addition, there is a limited application of the technology to be overcome in the future, such as environmental stability, safe reproducibility, productivity, economical efficiency of wastewater treatment for mass production. In addition, these two methods are difficult to control the coating amount during double-sided, single-sided plating, there is a limit in the combination of alloy composition.

In addition, in the case of the vacuum plating method in which an evaporation source is used to simultaneously form an alloy coating film by using two evaporation sources, in the case where the alloying material system with aluminum vaporizes such as manganese, chromium, magnesium, etc., it is a sublimable metal The following problems can be expected in mass production. In the case of a sublimable metal, evaporation with a large output electron beam takes into account the productivity, resulting in splash phenomenon of the evaporated metal, which makes it difficult to deposit uniformly, and the evaporation material surface during deposition reacts with the residual gas in the deposition vessel. Since it is easy to oxidize or nitrate, the evaporation rate may be changed on the surface, which may cause non-uniformity of the alloy composition. In addition, when the width of the deposited material steel sheet is large, there is a problem such as plating deviation of the plate surface occurs due to the difference in evaporation distribution due to uneven oxidation on the surface of the evaporation material.

Therefore, the present invention has been devised the following method for easily plating various plating materials in a vacuum container to solve these problems and to improve the characteristics of the plating material. The method does not use two evaporation sources in the production of aluminum-chromium alloy plated steel sheets by vacuum plating, and simultaneously evaporates from one evaporation source. The thickness is in the range of 10-50 g / m ² , and the chromium content is 1.8-11. It relates to a method for producing an aluminum-chromium alloy plated steel sheet, characterized in that it is prepared to be by weight%. The present invention will be described below.

The aluminum-chromium alloy film in the present invention was deposited in a vacuum of 5 × 10 ⁻⁵ Torr or less. First, the grain-shaped aluminum and chromium are put into a single evaporation source with a constant alloy composition, and then the substrate is mounted and evacuated by using a vacuum pump until the vacuum inside the vacuum vessel reaches 5 × 10 ^-5 Torr or less. As a substrate, a low carbon cold rolled steel sheet having a thickness of 0.5 mm was used, and ultrasonic cleaning using alkaline degreasing and an organic solvent was performed before charging into a vacuum container. When the vacuum level is less than 10 ^-5 Torr, the substrate is cleaned by glow discharge for 15 minutes by applying a negative voltage of 1000 V to the substrate in an argon gas atmosphere of about 10 ^-2 Torr to increase the cleanliness and activity of the substrate. .

The degree of cleanliness of the substrate is indirectly determined by reading the current flowing through the substrate. Initially, overcurrent flows irregularly due to discharge of impurities or oxide film, and then, when it is cleaned to some extent, a stable low current flows. This is because the current of the substrate is stabilized because there is no discharge of impurities and oxides. When the substrate is cleaned, the temperature of the substrate is adjusted to 150-400 ° C., and the gas contained in the surface and the inside of the single evaporation source and the evaporation material is supplied with a certain amount of power depending on the thickness and the surface of the evaporation source to degas the evaporation source. After degassing, aluminum and chromium are put into a single evaporation source with a constant composition, and a certain amount of power determined according to evaporation materials and evaporation conditions is supplied. After the aluminum and chromium are completely dissolved, the power size is adjusted at the preset evaporation rate to simultaneously evaporate two material systems with different evaporation temperatures from a single evaporator to produce an aluminum-chromium alloy film with the desired weight percent.

As the evaporation source, a boron nitride solidified by injecting liquid boron nitride onto the graphite bow in consideration of the reactivity between the evaporation material and the evaporation source, the evaporation source, the lifetime of the evaporation source, and the price was used. In the coating, the weight percent of chromium is 1.8-11%, and the total coating amount of the coating is 10 g / m ² or more. Limiting the weight and adhesion of chromium below, when the weight of manganese is less than 1.8%, the effect of adding chromium is reduced, and only aluminum monometal is present to prevent corrosion, and when it is more than 11%, the effect of chromium on the structure This is because the formation of a dense oxide film due to corrosion products is weak because it is changed to a structure where hole corrosion is likely to occur. The adhesion amount of the plating layer was limited to 10 g / m ² or more. When the adhesion amount is less than this, the pits in the plating film which prevents pitting corrosion increase, and pitting resistance (resistance to hole corrosion) decreases rapidly. Therefore, it is because the formation of the dense oxide film is not enough to protect the steel sheet.

In the ion plating method, aluminum and chromium were simultaneously evaporated from a single evaporation source, and a voltage of 100-1000 V was applied using a hot electron emission source and an ionization electrode to ionize the evaporation material and a negative voltage was applied to the substrate. .

Ion plating method applies a negative voltage to the substrate and heats the evaporation source by electron beam heating or resistive heating while applying a voltage of 100-1000V to the evaporation source. This is a method in which particles of a substance present in the glow discharge region are ionized and collide with the substrate of the cathode to form a film. Since the ion plating method can be deposited at a low temperature of 100 ~ 500 ℃ it can prevent the deformation of the matrix or the change of material that can occur in the high temperature process.

Compared to other chemical vapor deposition methods, chemical reactions are produced by sending the reactants in a gaseous state to a reaction zone in a high-temperature atmosphere to obtain a solid deposition layer on a desired substrate. Thus, a dense film is obtained without a regrinding process. There is an advantage that a surface having the same highly smooth coating can be obtained.

1 is a diagram showing the distribution of components along the depth direction using AES (Ozeo Electron Spectroscope) on a specimen prepared in such a way that a chromium content of 5.5% by weight on a 0.5 × 100 × 150 mm low carbon cold rolled steel sheet to be. Unlike the alloy coatings formed using two evaporation sources, it can be seen that aluminum and chromium are evenly distributed according to the depth direction as shown in the figure.

2 shows a sample prepared by evaporating aluminum and chromium separately from two evaporation sources instead of a single evaporation source so that the chromium content is 5.5% by weight on a 0.5 × 100 × 150 mm low carbon cold rolled steel sheet. The figure shows the component distribution along the depth direction by using. As shown in the figure, aluminum and chromium are distributed unevenly and irregularly and stiffly in composition according to the depth direction, as compared to the alloy coating formed using the single evaporation source of FIG.

3 is a diagram showing the initial blue-green generation time when the salt spray test using a 5% NaCl solution of aluminum-chromium alloy coating according to the weight percent of chromium. It shows very good corrosion resistance that the content of chromium is in the range of 1.8-11 wt% over 1000 hours. Through the present invention, by producing an aluminum-chromium alloy coating which realizes a plating product having excellent corrosion resistance with a much smaller adhesion amount than a conventional plating product by a single evaporation source, it is required for products requiring high corrosion resistance and high heat resistance in automobiles, home appliances, building materials, etc. It is expected to be used. In addition, by using one evaporation source rather than two evaporation sources, it is expected that the process can be simplified and economical when the sublimable metal is an alloying element.

In the following examples, the aluminum-chromium alloy film vacuum-plated by the method of the present invention was prepared and its characteristics were investigated. As a comparative material, vacuum-plated aluminum and chromium single plated products, and electric and hot dip zinc single plated products were used. . And the characteristics were compared with aluminum-chromium evaporated plated steel sheets deposited from two evaporation sources rather than a single evaporation source. As a property evaluation and comparison, the corrosion resistance test was performed and the results are shown in Table 1. Corrosion resistance was compared by initial red blue development time in 5% NaCl solution.

Example 1

For the evaporation of aluminum-chromium, a boat made by spray-coagulating liquid boron nitride on a graphite boat was used as an evaporation source. The substrate temperature was 250 ° C and the vacuum degree during evaporation was 5 × 10 ^-5 Torr. It is a product when it deposits by the ion plating method which applied the voltage of 500V to the low carbon steel plate of 0.5x100x150 mm with the weight of chromium 1.8% and the adhesion amount of 20g / m <^2> .

Example 2-7

Same as Example 1, but the weight of chromium 2.1, 2.5, 3.2, 5,5. It is a product at 8.5 and 11%.

[Comparative Example 1-7]

In the case of a product in which an aluminum-chromium 2, 3, 6, 8, 11, 13 wt% film produced by two evaporation sources was deposited on a 20 g / m ² low carbon cold rolled steel sheet.

Comparative Example 8

In the same manner as in Example 1 except that the weight of chromium is 0.7%.

Comparative Example 9

In the deposition of monometallic aluminum, using a boat of liquid solid boron nitride spray-coated on the graphite boat as the evaporation source, the substrate temperature is 250 ° C and the vacuum degree during evaporation is 20 x / m ² at 5 x 10 ^-5 Torr and 0.5 x 100 x This is the case for products deposited on 150 mm low carbon cold rolled steel sheets.

Comparative Example 11

This is the case for the product coated with 20g / m ² zinc monocoated product manufactured by electroplating method.

Comparative Example 12

This is the case of the product coated with 40g / m ² zinc monocoated product manufactured by hot dip plating method.

In the present embodiment and the following Table 1, only the substrate temperature of 250 ℃, the coating weight of 20g / m ² is shown only, in the present invention, the evaporation source may be any of resistive heating or electron beam heating method is deposited by ion plating method In the case where the plating deposition amount is 10 to 50 g / m ² in the substrate temperature range of 150 ~ 400 ℃ exhibited the same excellent corrosion resistance as in this embodiment.

Claims (1)

In the method for manufacturing an aluminum-chromium alloy plated steel sheet, aluminum and chromium are alloy compositions of chromium content of 1.8 to 11% by weight and placed in one evaporation source, and they are simultaneously irradiated with an electron beam and heated to evaporate to a substrate temperature of 200 to 300 ° C. a chromium alloy plating deposition plate - of the substrate steel sheet coating weight is 10 ~ 20 g / m aluminum to ² range for aluminum for vacuum depositing a chrome alloy plating layer by an ion plating method using an ionization electrode applying a voltage of 100 ~ 1000V Manufacturing method.