JP2701222B2 - Manufacturing method of vacuum-deposited Ti-plated steel sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a vacuum-deposited Ti-plated steel sheet having excellent corrosion resistance, workability and plating adhesion.

(Prior art) A plated steel sheet is an inexpensive material having excellent corrosion resistance, and thus has been used for various applications. However, in recent years, its use has been examined for Zn, Al, Zn-Al alloys, Zn-Al alloys, and the like. In Ni alloy plating and other applications, it extends to highly corrosive applications that can be corroded in a short time.

Although Ti-plated steel sheets are suitable for such applications, Ti is very active at high temperatures and has a high melting point, so that it is difficult to produce it by hot-dip plating. On the other hand, it can be manufactured by the non-aqueous solution electroplating method, but is very expensive. For this reason, Ti-plated steel sheets have conventionally been manufactured by a vapor phase method, and in particular, manufactured by a vacuum evaporation method in which Ti is dissolved and evaporated by an electron beam or the like to perform plating. This plating method has the advantages that the apparatus is simpler, the plating speed is faster, and a dense plating layer can be obtained as compared with other vapor phase methods.

(Problems to be Solved by the Invention) However, in the plating layer formed by the vacuum deposition method, there are pinholes, which are fine holes penetrating from the surface to the base steel plate, and only a hard and brittle plating layer can be obtained. .

When a pinhole is present, the base steel sheet becomes base to Ti in a normal environment such as the air environment, so that the base steel sheet is corroded from the pinhole portion and even if the plating layer has excellent corrosion resistance. And the corrosion resistance is inferior. Further, if the plating layer is hard and brittle, the ductility is inferior and the workability is poor.
In addition, when a taping test is performed in which the plated surface is outwardly bent 180 ° and a cellophane tape is applied to the bent portion and peeled off, the plated layer may be peeled off. This is due to oxidation of the base steel sheet before vapor deposition.

As described above, when the Ti-plated steel sheet was manufactured by the vacuum evaporation method, various problems still existed. Therefore, the present invention provides a method of manufacturing a Ti-plated steel sheet by the vacuum evaporation method that solves these problems. Is what you do.

(Means for Solving the Problems) The present inventors have pursued various reasons why a conventional vacuum deposition method cannot produce a vacuum-deposited plated steel sheet having excellent corrosion resistance, workability, and plating adhesion, and as a result, have found that a deposition chamber has been developed. Due to the relative values of H ₂ O and H ₂ gas present in the residual gas after evacuation, they have found that they can be controlled by appropriate means during vapor deposition.

That is, in the present invention, when a Ti-plated steel sheet is produced by applying Ti plating to a steel sheet by vacuum evaporation, the ion current of H ₂ O and H ₂ gas contained in the residual gas in the evaporation chamber is measured by a gas analyzer. By monitoring, the ion current intensity ratio was set to 5 or less, and the temperature of the steel sheet was set to 400 ° C. or more to perform the vapor deposition.

(Operation) When the vapor deposition chamber is set to the atmosphere, the material of the vapor deposition chamber and the vapor deposition substance adhering to the chamber absorb gas such as H ₂ O and O _{2 in the} atmosphere,
Release them on exhaust. However, these gases
Even if a high vacuum is applied, the gas cannot be exhausted completely, and remains as a residual gas in the vapor deposition chamber, affecting the characteristics of the plating layer.

However, H ₂ O gas occupying most of the residual gas is decomposed into H ₂ gas and O ₂ gas under high vacuum, and the influence on the plating layer is reduced.

Therefore, when the Ti deposition plating, the reduction degree of the H ₂ O gas H ₂ O
Ionic current intensity ratios by gas analyzer gas and H ₂ gas When the ratio is set to 5 or less, adsorption of H ₂ O gas on the deposition surface is suppressed in the plating layer growth step, and Ti
The atoms are sufficiently diffused on the surface, the plating layer becomes dense, and the generation of pinholes is prevented. In addition, since adsorption of O ₂ gas to the base steel sheet and inclusion in the plating layer are suppressed,
Plating adhesion and workability are also improved. Further, even if the heating temperature of the base steel sheet is lowered, good plating adhesion can be obtained.

In order to reduce the ion current intensity ratio between H ₂ O and H ₂ gas to 5 or less, an active metal such as Ti is charged into a vapor deposition chamber and then adsorbed on the metal, or exhaust is continued. It is sufficient to wait for the natural decrease.

As a gas analyzer for monitoring the ion currents of H ₂ O and H ₂ gas, a mass filter gas analyzer, for example, a quadrupole mass analyzer may be used. This analyzer is designed to measure the ion current of each component by measuring the components in the gas ionized under reduced pressure in order of mass,
To monitor the residual gas ion current in the vapor deposition chamber, connect to the vapor deposition chamber, set the inside of the mass filter to the same degree of vacuum as the vapor deposition chamber, or slightly reduce the pressure. And measure it.

When the gas is introduced into the mass filter, the gas is ionized at the quadrupole electrode and separated in order of mass, and the separated ions are detected by the ion collector or the detection unit having the secondary electron multiplier, and the mass is detected. The order of the ion current can be measured. Therefore, by comparing the intensity of the ion current, the relative value of each gas component can be confirmed. After the measurement, the connection valve is closed.

If the base steel sheet is heated to 400 ° C. or higher during the vapor deposition, the surface diffusion of Ti atoms incident on the vapor deposition surface becomes active, so that the plating layer becomes dense and the plating adhesion is improved.

To manufacture a Ti-deposited plated steel sheet according to the present invention, a gas analyzer is connected to the deposition chamber, and after the deposition chamber is evacuated to a high vacuum region, the residual gas is monitored. Next, in Haas
The Ti was predissolved, after adjusting to the desired Ti evaporation rate, to confirm that the ionic current intensity ratios between H ₂ O and H ₂ gas in the gas analyzer becomes 5 or less, heating the base steel sheet , Steel plate temperature is 40
Start plating when the temperature reaches 0 ° C or higher.

(Example) Ti corresponding to JIS Class 1 was put in a water-cooled copper hearth in a vacuum evaporation chamber, and a cold-rolled steel sheet degreased was placed above the vacuum evaporation chamber to a degree of vacuum of 2 × 10 ^-3 to 2 × 10 ^-4 Pa,
Dissolution and evaporation of Ti with electron beam, deposition rate 10μm / mi
In step n, Ti was deposited on the cold-rolled steel sheet.

At the time of vapor deposition, the ion current of H ₂ O and H ₂ gas in the residual gas in the vapor deposition chamber was monitored by a quadrupole mass spectrometer,
Its intensity ratio Was adjusted, and the cold-rolled steel sheet was heated with an electron beam, and the temperature was measured with an infrared radiation thermometer.

Next, the following items were investigated for the obtained Ti-deposited plated steel sheet.

(1) Plating layer fracture surface structure A plated steel sheet is fractured in liquid N ₂ , a fine dimple pattern is observed on the fracture surface as a ductile fracture surface, and a porous pattern is observed on a brittle fracture surface. did.

(2) Hardness of plating layer Measured with a Vickers hardness tester.

(3) Presence or absence of pinhole Investigation was made by a ferroxil test.

(4) Plating adhesion After 180 ° bending with the Ti plating side facing out,
A cellophane tape was stuck to the bent portion and peeled off, and the amount of Ti adhering to the tape was visually observed.

 Table 1 shows the relationship between the deposition conditions and the inspection results.

As shown in Table 1, the Ti plated steel sheet manufactured according to the present invention has no pinhole in the plated layer. Further, the plating layer fracture cross-sectional structure is a ductile structure, the hardness is close to that of pure Ti, and the plating adhesion is also good.

(Effect of the Invention) As described above, according to the present invention, there is no pinhole,
In addition, it is possible to manufacture a Ti-plated steel sheet having a plating layer having excellent workability and adhesion.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshiharu Tachibana Taka 5 Ishizunishimachi, Sakai City, Osaka Prefecture Nisshin Steel Corporation Hanshin Research Laboratory (56) References 61-73880 (JP, A) JP-A-50-75132 (JP, A)

Claims (1)

(57) [Claims] 1. A steel sheet is subjected to Ti plating by vacuum
When manufacturing a plated steel sheet, the ion current of H ₂ O and H ₂ gas contained in the residual gas in the deposition chamber is monitored by a gas analyzer, and the ion current intensity ratio is reduced to 5 or less. A method for producing a vacuum-deposited Ti-plated steel sheet, wherein the vapor deposition is performed at a temperature of 400 ° C. or higher.