JPH036360A - Manufacture of surface treated titanium sheet - Google Patents

Abstract

PURPOSE:To manufacture the surface treated titanium sheet having good wettability and easily executable of brazing in the air by applying specified coating weight of Ni coating onto a titanium material as a hot rolled sheet or that as cold-rolled and diffusing Ni into a base metal phase through a heating stage. CONSTITUTION:A titanium mterial as a hot rolled sheet before undergoing cold rolling stage or that as cold-rolled before undergoing an annealing stage is applied with Ni coating by the method of electroplating, electroless plating or the like. The coating weight of Ni is regulated to the one corresponding to 20 to 60g/m<2>, expressed in terms of a produced sheet having finish thickness after the final stage. Next, the Ni coated titanium sheet is subjected to heating treatment such as annealing until transformed into a product to diffuse and permeate Ni into a base metal phase. This heating treatment is executed suitably at about 550 to 850 deg.C for about 10sec to 4hr; at this time, according to necessary, a part of Ni is allowed to remain as an Ni phase, by which an appearance having a white gloss can be obtd. By this surface treatment, an Ni permeating layer having good adhesive properties is formed to obtain the titanium sheet having good wettability, executable of brazing in the air and furthermore having excellent soldability and plating properties.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a titanium plate, and particularly to a method for surface treatment of a titanium plate that has good wettability and is easy to braze in the atmosphere.

[Conventional technology]

Titanium has various advantages and characteristics compared to stainless steel sheets, etc., such as being lightweight and having excellent corrosion resistance, as well as being non-magnetic and having a low coefficient of thermal expansion. However, titanium has poor wettability and cannot be plated, soldered or brazed. It also has disadvantages such as being difficult to use. Therefore, although it has the potential to be used in a wide variety of applications as components for daily necessities, electrical appliances, vehicles, accessories, etc., it has not yet been widely used in fields that require these characteristics.

As a measure to improve surface properties such as wettability, Japanese Patent Application Laid-open No. 1983-
As disclosed in Japanese Patent Application No. 82161, etc., a method has been proposed for brazing, such as plating with Ni or the like beforehand.

However, it is difficult to plate the titanium surface with Ni or other materials with good adhesion, and as a pre-treatment method for plating to improve this, hydrofluoric acid, etc., as disclosed in JP-A-58167795, etc., is used. Various methods have been proposed, such as pre-activation treatment using electrolytic polishing or the like. Even with these methods, (1) (2) it is difficult to apply thick plating with good adhesion, and as the processing process becomes more complex, it becomes even more difficult to apply plating, soldering, or brazing to specific parts. Furthermore, there is also the problem that the appearance of the product is likely to be damaged by the chemical solution.

[Problem to be solved by the invention]

The present invention is an attempt to fundamentally solve the problems of conventional titanium plates that are difficult to handle during product processing, such as poor wettability and difficulty in plating or brazing, on the titanium plate manufacturing side. The purpose of this invention is to establish a method for manufacturing titanium plates to provide a completely new titanium plate that greatly reduces the burden on customers such as product processing manufacturers.

[Means to solve the problem]

In order to solve these problems, the present inventors conducted various studies on the effect of additive elements or the effect of metal coating in the pre-manufacturing process. It has been found that forming it on the surface layer of the plate is effective in improving wettability. Therefore, we further investigated a method for efficiently forming this minute amount of Ni permeation layer in the manufacturing process of titanium plates, and came to construct the present invention.

That is, in the present invention, the Ni coating is applied to a hot-rolled plate before the cold-rolling process or to a titanium material as cold-rolled before the annealing process. te2
N
An object of the present invention is to provide a method for producing an annealed titanium plate with good wettability, which is characterized by diffusing i into a base metal phase.

[For production]

Hereinafter, a method for implementing the present invention will be explained in detail.

The type and structure of titanium used in the present invention may be pure titanium or alloyed titanium, in other words, titanium having an α phase, a β phase, or a mixed structure thereof.

In the present invention, the Ni coating is applied to a hot-rolled titanium plate or a cold-rolled titanium plate in the process of being manufactured.

In the present invention, the Ni coating undergoes a heating process to diffuse and penetrate into the base metal phase before it is finished.

Ni coating on the titanium material can be done by the electroplating method, electroless plating method, etc. after pickling with nitric-fluoric acid mixed aqueous solution etc. in the above-mentioned intermediate process, or as it is, or by performing anodic electrolysis treatment etc. in an alkaline solution. However, the electroplating method is preferable because it provides excellent coating uniformity, can easily form a thin coating, and can be easily operated continuously. Note that in the present invention, the adhesion of the Ni coating film does not pose much of a problem. The reason for this is that due to the heat treatment in the annealing step after coating, the Ni portion of the coating metal interdiffuses with titanium, and as a result, penetrates into the titanium, ensuring strong adhesion.

In the present invention, the Ni coating amount is more than 20g/m゛ in terms of the final thickness of the product plate after the final manufacturing process, and 6Q
gr/rn' or less. Therefore, if the reduction in thickness during the intermediate process is large, the amount of coating by plating or the like is naturally increased, that is, the coating thickness is increased. For example, if the plate thickness is reduced to 1/4 in the process after coating, the amount of coating at the time of coating is more than 80gr/m' and less than 240gr/m',
The coating thickness may be approximately 9 to 23 r.

As described above, in the present invention, the coating amount is specified by the amount of Ni per unit area for the product board that has undergone the final process and has a finished thickness. The first reason for this is, of course, that the amount of Nl in the product plate is of primary importance, but another reason is that the thickness of the plate at the time of coating varies widely depending on the process, that is, the rate of reduction in plate thickness differs. It is important to note that it is not strict to indicate the coating thickness at the time of coating, and that the N
Since a part of i penetrates into the surface layer of the titanium plate, Ni
This is because it is not appropriate to indicate the film thickness. In addition,
If the coating amount specified in the present invention is more than 20gr/m'' and less than 60gr/m', it is converted to coating thickness of about 23n~
It will be on the 6.8 side.

(5) (6) If the coating amount is less than 20 gr/m', it may be sufficient to improve wax entrainment in vacuum, but it is insufficient to improve wax properties in the atmosphere; If m' is exceeded, the effect of improving wax properties in the atmosphere becomes saturated, which is disadvantageous in terms of cost.

The heating conditions, that is, the annealing conditions after cold rolling, vary depending on the Ni coating thickness, cold rolling reduction rate, and purpose of use, and are difficult to specify, but the annealing temperature range is 550 to 850°C.
The annealing retention time is preferably a relatively long time when the annealing temperature is low, and a short time when the annealing temperature is high, and is preferably about 10 seconds to 4 hours in both cases. When the annealing condition is kept at a temperature lower than 550°C for a short time, Ni and Ti
There is little interdiffusion between Ni
In addition to insufficient adhesion of the coating, the effect of improving wax properties is also insufficient.

In addition, as another embodiment of the present invention, there is a method of actively leaving an extremely thin layer of Ni on the outermost surface layer of the titanium plate. Such a state can be obtained by increasing the Ni coating amount and making the constant time short. When applying Ni coating to a hot-rolled sheet, if the cold-rolling reduction ratio is too small, the cold-rolled structure tends to remain, resulting in insufficient softening by annealing, or
Requires long annealing. Therefore, it is desirable that the cold rolling reduction ratio in this case be at least 40% or more.

In this way, by positively leaving a very thin layer of Ni on the outermost surface layer of the titanium plate, it becomes white and has a glossy appearance, and the waxiness in the atmosphere is also significantly improved.

In the present invention, annealing is performed in a vacuum, in an atmosphere surrounded by an inert gas such as argon, or in the air, and then descaling is performed by nitric-fluoric acid pickling or salt treatment as necessary. Since the degree of oxidation is slight, it is also possible to omit salt treatment, which has a large downside in terms of workability and cost.

〔Example〕

Examples of the present invention will be described below.

(7) (8) Example-1 After hot-rolling, a hot-rolled pure titanium plate with a plate thickness of 3 mm that was annealed at 800°C for 1 minute was pickled with a nitric-hydrofluoric acid solution.
30gr/fl NaOH and 30gr/p H2
A plating pretreatment was performed by anodic electrolysis in a mixed aqueous solution of O2, and then Ni plating was applied to both sides using the electroplating method using a Watts bath to a thickness of 20 μm, resulting in a plate thickness of 0.8 cm.
The coating amount converted to a product sheet of 47 gr/m') was further cold rolled to a thickness of 0.8 mm, and then annealed at 750°C for 1 minute in an argon atmosphere, followed by 4 % nitric acid + 1% HP solution for 2 minutes for pickling treatment.

It should be noted that the Ni coating amount per one side of the titanium plate produced by the method of the present invention, including the residual Ni phase, is determined as the surface layer 2.
When measured for 0jml, it was 12gr/m'.

For comparison, a titanium plate with a thickness of 0.8 mm was also produced which was treated in the same manner as described above without being coated with Ni.

In order to investigate the brazing properties of these titanium plates, brazing was performed using low-temperature silver solder in the atmosphere with n number of 20, and the strength of the brazing was 9 to 13 kgf in the case of the titanium plates according to the present invention. /mm2, and in the case of the comparative titanium plate, brazing was impossible.

From these results, it is clear that the titanium plate according to the present invention has high strength when brazed and can be uniformly brazed.

Example 2 A cold-rolled pure titanium plate with a thickness of 0.8+n+n was subjected to anodic electrolysis treatment in an alkaline solution, and then electroplated using a Watt bath to a plating thickness of 3.6. Ni plating was applied to both sides at a rate of 32 gr/m' (converted to the coating amount of a product board of the same thickness), and then heated at 700°C in an argon atmosphere.
Annealing was carried out for 10 minutes with 4% nitric acid + 2
% hydrofluoric acid solution for 10 seconds for pickling treatment.

The amount of Ni coated on one side of the titanium plate produced by the method of the present invention was measured for 511 m of the surface layer including the residual Ni phase, and was found to be 28 gr/m'.

(9) (10) For comparison, a titanium plate with a thickness of 0.8 mm that was treated in the same manner as described above without being coated with Ni was also produced.

The brazing strength of these titanium plates was measured using the same method as in Example 1 with n number 20, and the results showed that the titanium plates made by the method of the present invention had a strength of 11 to 15 kgf/m.
m2, brazing was not possible with the titanium plate of the comparative example.

Further, in order to investigate plating adhesion, after electrolytic degreasing with an alkaline solution, Ni plating was applied using a Watts bath at a current density of 4 A/dm2, and the critical peel plating thickness was determined by a taping peel test. As a result, on the titanium plate of the comparative example, almost no plating adhered, and even if it did, it peeled off when the plating thickness reached about 2 IPm, whereas on the titanium plate manufactured by the method of the present invention, the plating layer peeled off until the plating thickness reached 100 mm. I didn't.

From the above results, it is clear that the titanium plate produced by the method of the present invention has excellent waxing properties and plating adhesion.

〔Effect of the invention〕

As detailed above, titanium plates manufactured by the method of the present invention can be soldered in the atmosphere, have excellent solderability, and can be easily plated. It can greatly reduce the burden on customers such as product processing manufacturers when using the board.
The benefits to related industrial fields are extremely large.

Claims (2)

[Claims] (1) For hot-rolled sheets before the cold rolling process or as-cold-rolled titanium materials before the annealing process, the amount of coating exceeds 20gr/m^2 and 60gr/m^2 in terms of the finished plate thickness after the final process. m^
1. A method for manufacturing a surface-treated titanium plate, characterized in that Ni is coated with Ni to a surface-treated titanium plate having a surface-treated titanium plate of 2 or less. (2) The method for producing a surface-treated titanium plate according to claim 1, characterized in that when Ni is diffused into the base metal phase, a portion of the Ni is left as a Ni phase.