JPH08296071A - Method for dulling titanium material surface - Google Patents

Abstract

PURPOSE: To provide a method for dulling the surface of a titanium material by the picking using an aq. soln. of nitric-hydrofluoric acids contg. Fe, Cr and Ni ions. CONSTITUTION: A titanium material is pickled with an aq. soln. of nitric- hydrofluoric acids to dull its surface. In this case, a titanium material having <=20μm crystal grain diameter is used, the hydrofluoric acid concn. (a) in the aq. soln. is controlled to 3-100g/L, the nitric acid concn. (b) is adjusted to 0.07 to 0.8 times the hydrofluoric acid concn. (i.e. b/a=0.07 to 0.8). The sum (c) of the Fe, Cr and Ni ions inevitably contained in the soln. is limited to conform to 1.25b/(a+c)/a<=1.0. The soln. is kept at 25-45 deg.C, the titanium material is pickled, hance fine ruggedness of the crystal grain unit is formed on the material surface, and a titanium material having <=50% glossiness Gs45 deg. and excellent in antidazzle characteristic is produced in pickling equipment shared with stainless steel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a titanium material having excellent antiglare property, and more particularly to a method for producing a titanium material which is uniform and has no stain and excellent antiglare property in a short time. .

[0002]

2. Description of the Related Art Since titanium is excellent in corrosion resistance and specific strength, it has recently become maintenance-free for buildings in coastal areas and hot spring areas, which are severely corrosive environments, or roofs and outer walls in high places where workability is poor. It is used in an oriented manner.
When used as an exterior material for such a building, a surface having an antiglare property is required because a normal metallic luster causes a glare in a landscape, and a glossiness Gs which is an index of the antiglare property is required.
45 ° (incident angle 45 ° by method 4 of JIS Z8741,
It is desirable that the light receiving angle is 45%).

In order to reduce the glossiness, it is effective to form fine irregularities having random plane directions on the surface to make the surface dull and enhance diffused reflection of light. Conventionally, as a method of forming irregularities on the surface of a plate, there is a method of rolling the plate using a roll having an irregular surface by shot blasting or the like and transferring the surface form of the roll to the plate. However, with this method, the size and shape of the irregularities that can be formed on the roll surface are limited, and only rough irregularities (the number of convex portions per 1 mm is about 10) can be transferred to the plate surface. It can only be reduced to about 1/3.

As a method of pickling titanium with an aqueous solution of nitric hydrofluoric acid, for example, in a descaling method of a titanium plate according to Japanese Patent Publication No. 4-72914, the concentration of hydrofluoric acid is 2 to 20 (g / g).
l), a method of using a nitric hydrofluoric acid aqueous solution having a nitric acid concentration of 50 to 200 (g / l) is disclosed. However, the surface of the titanium material pickled with such an aqueous solution of nitric hydrofluoric acid is smooth, and the antiglare property is poor. Further, Japanese Patent Publication No. 6-10329 describes a method of pickling a plate having a crystal grain size of 5 to 25 μm produced by continuous annealing in a pure titanium thin plate for building materials. However, the surface skin excellent in antiglare property cannot be obtained only by adjusting the crystal grain size.

On the other hand, for pickling titanium, pickling equipment for stainless steel is often used in common. In this case, metal ions such as Fe, Cr and Ni are present in the pickling solution. The presence of these metal ions makes the pickled surface smooth.
Further, even if the liquid is replaced with a new liquid, the metal ions cannot be completely removed, and about 0.1 to 5 g / l remains. As described above, there is no method for producing a titanium material having excellent antiglare property with stainless steel and the same pickling equipment, and the effect of cost reduction by sharing the equipment with stainless steel cannot be expected.

[0006]

The present invention is based on Fe, C
A titanium material excellent in antiglare property is manufactured by using an aqueous solution of nitric hydrofluoric acid in which r and Ni ions are present to form a dull surface having a gloss Gs of 45 ° of 50% or less by pickling. The purpose is to provide a method.

[0007]

That is, the gist of the present invention is as follows. In the method of pickling the titanium material by pickling the titanium material with a nitric hydrofluoric acid aqueous solution,
A material having a crystal grain size of 20 μm or less is used as the titanium material, and the hydrofluoric acid concentration a in the nitric hydrofluoric acid solution is 3 to 100.
(g / l), the nitric acid concentration b (g / l) is 0.07 to 0.8 times the hydrofluoric acid concentration a (that is, b / a =
0.07 to 0.8) and the total value c of the Fe, Cr, and Ni ion concentrations that are unavoidably contained in the aqueous solution of nitric hydrofluoric acid.
(G / l) and the hydrofluoric acid concentration a and nitric acid concentration b satisfy the condition (1), and the liquid temperature is 25 to
A surface dulling method for a titanium material, which comprises performing pickling treatment at 45 ° C.

1.25b / a + c / a ≦ 1.0 (1) formula

[0009]

The present invention will be described in detail below. The inventors of the present invention used an aqueous solution of nitric hydrofluoric acid in which Fe, Cr, and Ni are dissolved to form uniform and fine irregularities on the surface of titanium to reduce glossiness. As a result of studying the pickling method with an aqueous solution, the following has been found out.

In the following description, the hydrofluoric acid concentration in the nitric hydrofluoric acid aqueous solution is a, the nitric acid concentration is b, and the total value of Fe, Cr, and Ni ion concentrations is c. FIG. 1 is a diagram showing the relationship between the surface roughness Rmax after pickling and the total value c of Fe, Cr, and Ni ion concentrations in each nitric hydrofluoric acid aqueous solution. As shown in FIG. 1, even if the aqueous solution of hydrofluoric acid is a corrosive form that originally forms fine irregularities in the crystal grain unit on the surface of titanium, Fe and C
When the total value c of r and Ni ion concentration is increased, the surface is uniformly ablated and changed into a corrosion mode in which the surface is smoothed, and the effect of reducing the glossiness is lost. Further, the smaller the nitric acid concentration b (that is, b / a) with respect to the hydrofluoric acid concentration a, the more Fe and C
The surface can be roughened to a range where the total value c of r and Ni ion concentrations is high.

FIG. 2 shows a composition region of a pickling solution having a sufficient ability to form irregularities (nitric acid concentration b: b / a for hydrofluoric acid concentration a: total Fe, Cr, Ni ion concentration for hydrofluoric acid concentration a: c:
It is a figure which shows (it represents with c / a). As shown in FIG. 2, the composition of the pickling solution for forming fine irregularities on the surface is a, b, c.
Is a region that satisfies the expression (1). Where nitric acid concentration b
Is more than 0.8 times the hydrofluoric acid concentration a (b / a> 0.8), if less than 0.1 (g / l) Fe, Cr, Ni ions are contained, the corrosion morphology changes and the surface Uneven formation of Further, when the nitric acid concentration b is less than 0.07 times the hydrofluoric acid concentration a (b / a <0.07), the oxidizing power of the aqueous solution is lowered, so that titanium is in the +2 or +3 state. Corrosion products of color or dark purple are generated, and the surface is stained. When b / a is 0.07 to 0.8, this stain does not occur when Fe, Cr, and Ni ions are contained. Therefore, the nitric acid concentration b is 0.07-0.
The range was set to 8 times (that is, b / a = 0.07 to 0.8) and the total value c of hydrofluoric acid concentration a, nitric acid concentration b, Fe, Cr, and Ni ions satisfied the formula (1). Preferably, the nitric acid concentration b is 0.1 to 0.5 times the hydrofluoric acid concentration a (that is, b
/A=0.1 to 0.5) is preferable.

FIG. 3 is a view showing the surface profile of skin pickled with an aqueous solution having a composition in the above range for forming irregularities on the surface, and FIG. 4 is pickled with an aqueous solution having a composition in the above range for forming irregularities on the surface. It is a figure which shows the relationship between the glossiness Gs45 degrees of the formed surface, and a crystal grain size. As shown in FIG. 3, the smaller the crystal grain size, the greater the number of irregularities per unit length. As a result, as shown in FIG. 4, diffuse reflection of light is increased and the glossiness Gs45 ° is reduced. When the crystal grain size is 20 μm or less, the gloss Gs45 ° is 50% or less. Therefore, the crystal grain size is 2
It was set to 0 μm or less. It is preferably 3 to 15 μm.

In FIG. 5, the nitric acid concentration b is 0.07 with the hydrofluoric acid concentration a.
Fe, Cr, Ni at double (that is, b / a = 0.07)
It is a figure which shows the range of the hydrofluoric acid concentration a and liquid temperature suitable for pickling when the total value c of ion concentration satisfies Formula (1). Figure 5
, The hydrofluoric acid concentration a is less than 3 g / l, the liquid temperature is 25 ° C.
If it is less than, it is hardly abraded. Also, hydrofluoric acid concentration a
Is more than 100 g / l, the liquid temperature rises sharply, making it difficult to control the liquid temperature. Further, when the liquid temperature exceeds 45 ° C., the nitric acid oxidization power is insufficient and the same stains as described above occur. Therefore, as a region where a surface which can be abraded and has no dirt can be obtained, the hydrofluoric acid concentration a is 3 to 100 g / l, and the liquid temperature is 25 to 45.
° C. Preferably, the hydrofluoric acid concentration a is 15 to 80 g /
1, the liquid temperature is preferably 30 to 40 ° C. Here, when the liquid temperature is high, it is considered that the generation of stains is caused by the fact that the reaction of fluorination and hydrogenation with hydrofluoric acid becomes more active than the oxidation reaction of nitric acid.

The pickling method here is, for example, a method of immersing the titanium material in the pickling solution or a method of spraying the pickling solution.
Titanium materials are those that have been cold worked such as cold rolling or annealed in an inert gas atmosphere such as vacuum or Ar, or have their scales damaged or modified by shot blasting or salting after atmospheric annealing. It is a thing. Here, the stainless steel is 18Cr-8Ni steel (SUS304) or the like.

[0015]

The present invention will be described in more detail with reference to the following examples. After cold rolling a plate of industrial pure titanium (JIS type 1) having a thickness of 3 mm to a thickness of 0.4 mm, the plate was manufactured by steps A and B as described below, and the surface skin was examined. Step A: atmospheric annealing → salt treatment → nitric hydrofluoric acid pickling Step B: annealing in Ar gas atmosphere → nitric hydrofluoric acid pickling Here, the salt treatment contains sodium hydroxide as a main component and sodium nitrate as an oxidizing agent. 500 for salt
It was immersed at 30 ° C. for 30 seconds.

Table 1, Table 2 (continued from Table 1-1), Table 3
(Continued-2 of Table 1), Table 4 (Continued-3 of Table 1), Table 5 (Continued-4 of Table 1), Table 6 (Continued-5 of Table 1) Washing conditions (composition, liquid temperature, immersion time), amount of fusing, gloss after pickling Gs 45 ° (JIS Z
The method 4 of 8741 shows the case where the incident angle is 45 ° and the light receiving angle is 45 °), and the presence or absence of residual scale or stain.

Here, the pickling solution is SUS3 in a nitric hydrofluoric acid aqueous solution.
A mixture of 04 solution and hydrofluoric acid and nitric acid was used. Further, the glossiness Gs45 ° of the plate was about 150 to 200% in the state where the annealing was performed in the Ar gas atmosphere in the process B.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

From the results shown in Tables 1 to 6, the crystal grain size, the composition of the pickling solution (hydrofluoric acid concentration a, nitric acid concentration b, Fe, Cr, Ni ion concentration total value c) and the liquid temperature were determined according to the present invention. The samples in the range have a gloss Gs of 45 ° of 50% or less as a result of being sufficiently abraded to form fine irregularities on the surface. On the other hand, when the crystal grain size or the composition of the pickling solution is out of the range of the present invention, the glossiness Gs45 ° exceeds 50%. Further, the hydrofluoric acid concentration a and the liquid temperature are out of the range of the present invention, and the nitric acid concentration b is less than 0.07 times the hydrofluoric acid concentration a (that is, b / a <0.
If it becomes 07), the amount of ablation is insufficient, scale remains, stains are generated, and the liquid temperature rises rapidly, which is unsuitable.

[0025]

By applying the present invention, Fe, C
Pickling with an aqueous nitric hydrofluoric acid solution containing r and Ni ions is uniform and free of stains, and the glossiness Gs 45 ° is 50%.
The following titanium materials having excellent antiglare properties can be produced.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a surface roughness Rmax after pickling and a total value c of Fe, Cr, and Ni ion concentrations in each aqueous solution of nitric hydrofluoric acid.

FIG. 2 is a composition region of a pickling solution having a sufficient ability to form irregularities (nitric acid concentration b: b / a for hydrofluoric acid concentration a, and Fe, Cr, and Ni ion concentration total values c: c / a for hydrofluoric acid concentration a). It is a figure which shows).

FIG. 3 is a diagram showing a cross-sectional profile of the surface morphology of (a) and (b) in FIG. 4, where (a) is pure titanium having a crystal grain size of 5 μm in a hydrofluoric acid concentration of 50 g / l and a nitric acid concentration of 15 g. / L,
Total value of Fe, Cr, Ni ion concentration 20.03g / l
Shows the surface profile after pickling with a nitric hydrofluoric acid aqueous solution. (B) shows pure titanium having a crystal grain size of 40 μm with a hydrofluoric acid concentration of 50 g / l, nitric acid concentration of 15 g / l, Fe, Cr, and Ni ion concentrations. The surface profile after pickling with a nitric hydrofluoric acid aqueous solution having a total value of 20.03 g / l is shown.

FIG. 4 is a diagram showing a relationship between a glossiness Gs45 ° and a crystal grain size.

FIG. 5 shows a case where the nitric acid concentration b is 0.07 times the hydrofluoric acid concentration a (that is, b / a = 0.07) and the total value c of Fe, Cr, and Ni ion concentrations satisfies the formula (1). It is a figure which shows the area | region of the hydrofluoric acid density | concentration a and liquid temperature suitable for pickling.

Front page continuation (72) Inventor, Yoshiaki Nishida, Komitsu City, Oshima 3434, Shimada, Nippon Steel Co., Ltd., Kogaku Steel Works (72) Inventor, Kinichi Kimura, Komitsu City, Shimada, 3434, Shimada, Nippon Steel Co., Ltd. Inside the Steel Works (72) Inventor Ryosuke Matsuhashi 3434 Shimada, Shinjuku City Shin-Nihon Steel Co., Ltd. Inside the Hikari Works (72) Inventor Masaki Masaki, 3434 Shimada, Nippon Steel Co., Ltd. Inside the ironworks

Claims (1)

[Claims] 1. A method of pickling a titanium material by pickling a titanium material with an aqueous solution of hydrofluoric acid, wherein a material having a crystal grain size of 20 μm or less is used as the titanium material, and the concentration of hydrofluoric acid in the aqueous solution of hydrofluoric acid is used. a is 3 to 100 (g / l), and the nitric acid concentration b (g / l) is 0.07 to the hydrofluoric acid concentration a.
Fe that is 0.8 times (that is, b / a = 0.07 to 0.8) and is unavoidably contained in the aqueous solution of hydrofluoric acid,
The total value c (g / l) of the Cr and Ni ion concentrations and the hydrofluoric acid concentration a and the nitric acid concentration b are set to satisfy the condition (1), and the pickling treatment is performed at a liquid temperature of 25 to 45 ° C. A method for forming a surface dull of a titanium material, which is characterized in that 1.25b / a + c / a ≦ 1.0 (1) Expression