JPH10185797A - Evaluation method for corrosion resistance of alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an evaluation method in which the corrosion resistance of an alloy is evaluated in a short time by a method wherein an alloy is changed into a powder, the powder is immersed in an aqueous solution which conforms to an environment to be evaluated and the weight change, of the alloy, which is generated during its immersion is measured. SOLUTION: An alloy is changed into a powder, the powder is immersed in an aqueous solution which conforms to an environment to be evaluated, and the weight change, of the alloy, which is generated during its immersion is measured. When the alloy is changed into the powder, its specific surface area is increased, and the alloy is easily affected in the environment to be evaluated. Then, when the alloy is affected such as corroded or the like, its weight is increased generally. Consequently, when its weight change is measured, the corrosion on the surface of the powder alloy can be estimated easily, and the corrosion resistance of the alloy can be evaluated in a short period. The particle size of the powder alloy is set in a range of 50 to 100μm, and its average is set desirably at 70 to 80μm. Thereby, when an optimum alloy is to be selected from many candidates, a result can be obtained quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the corrosion resistance of an alloy.

[0002]

2. Description of the Related Art Thermal spray coating of an alloy is known as an anticorrosion film for cast iron tubes. Before performing the thermal spray coating, it is necessary to evaluate the corrosion resistance of the alloy.

Conventionally, this corrosion resistance evaluation is performed by burying the alloy in soil or immersing it in a test solution for setting the environment to be evaluated such as tap water, saline solution or sulfuric acid solution, and visually observing the corrosion resistance of the surface. I was going.

[0004]

However, the above evaluation method requires at least one month to obtain a clear evaluation result, and more than one year to obtain a clear evaluation result. Therefore, an optimum material is searched for from a large number of candidate materials. As in the test, there is a problem that it takes too much time and is unsuitable as an evaluation method when a large number of test objects are used.

[0005] The present invention has been made to solve the above problems.

[0006]

That is, in the method for evaluating the corrosion resistance of an alloy according to the present invention, the alloy is powdered, the powder is immersed in an aqueous solution suitable for the environment to be evaluated, and the weight change of the alloy caused during immersion is obtained. Is measured.

[0007]

When the alloy is powdered, the specific surface area with respect to the weight of the alloy increases, and the alloy is easily affected in the environment to be evaluated.

[0008] The weight of an alloy generally increases if it is affected by corrosion or the like. Therefore, by measuring the change in weight, the corrosion of the powder alloy surface can be easily estimated, whereby the corrosion resistance of the alloy can be evaluated within a short period of time.

The particle size of the powder alloy is desirably in the range of 50 to 100 μm, with an average of 70 to 80 μm. If the particle size is smaller than 50 μm, it is difficult to obtain the particle size. If the particle size is larger than 100 μm, the specific surface area becomes small, and accurate and accurate measurement results cannot be obtained.

In the above range, an average of 70 to 80 μm
Is a preferable range from the viewpoint of the measurement accuracy and the ease of obtaining the particle size of the powder. In addition, the aqueous solution compatible with the environment to be evaluated is
It refers to tap water, saline, or an acidic aqueous solution such as sulfuric acid or hydrochloric acid.

[0011]

Next, an embodiment of the present invention will be described. The following aluminum alloys and the like were prepared as target metals.

(1) Al-12Si-15Fe alloy (2) Al-4Si-15Mn alloy (3) Al-8Si-15Mn alloy (4) Al (5) Zn (6) Fe-50Si alloy Each of the metals 1) to (6) was made into a powder having a particle size of 50 to 100 μm, and each powder was accurately measured in an amount of 1 g and placed in a clean beaker.

Next, as the reference water for the evaluation environment, (a) pH
10 ml each of a 2.8 sulfuric acid aqueous solution, (b) 3% saline solution, and (c) tap water were added, and these were allowed to stand at room temperature for 5 days. After 5 days, each powder was stirred and washed with distilled water, dried, and weighed. The results are shown in Table 1.

Table 1 Weight change inspection items (a) (b) (c) (1) Al-12Si-15Fe alloy + 2.0% + 12.87% + 3.49% (2) Al-4Si-15Mn Alloy + 0.25% + 6.97% + 5.83% (3) Al-8Si-15Mn alloy + 0.54% + 8.05% + 3.35% (4) Al + 0.25% + 49.52% + 2.90% (5) Zn + 2.1% +2.00 % + 1.48% (6) Fe-50Si alloy + 0.03% + 0.07% + 0.04% In Table 1, + in the item of weight change indicates weight increase.

As is apparent from Table 1, according to the results of the judgment according to the method of the present invention, the tendency of the corrosion resistance of the metal to each aqueous solution is clearly seen, and the alloy which took more than one month in the prior art is shown. It was found that the corrosion resistance of the steel sheet could be evaluated in a short period of about one week.

[0016]

As described above, according to the method of the present invention, the corrosion resistance test of the alloy, which has conventionally required a very long time, can be completed in a short period of about one week, so that a very large number of candidates can be obtained. When it is desired to select an optimum alloy from the above, the effect is obtained that the result can be obtained quickly.

Therefore, if a candidate metal is selected by this method, the effect of simplifying the final selection of the optimum alloy can be obtained.

Claims (1)

[Claims] 1. A method for evaluating corrosion resistance of an alloy, comprising: forming an alloy into a powder; immersing the powder in an aqueous solution suitable for an environment to be evaluated; and measuring a weight change of the alloy generated during the immersion.