JPS60114739A - Grinding and corrosion of ti - Google Patents

Abstract

PURPOSE:To enable the observation of structure with a microscope by a method wherein after ground, a titanium test piece undergoes a finish grinding emmersed into an aqueous solution of hydrogen fluoride and then, corroded in an aqueous solution of hydrogen fluoride and nitric acid. CONSTITUTION:Pure titanium is used as test piece and ground with an abrasive paper, then with a paste containing fine diamond grits (6mum) and finally with a fine grit grinding agent containing fine grits of alumina (0.06mum). Then, the test piece is emmersed into a liquid of 1cc of 47% hydrogen fluoride +10-20cc of water for several sec and then, undergoes a finish grinding with an alumina fine grit grinding agent. Then, the ground surface of the test piece is corroded in a liquid of 1cc of 47% hydrogen fluoride +12cc of 69% nitric acid +50-60cc of water. This makes the grain boundary look clear noticeably eliminating uneven corrosion.

Description

Detailed Description of the Invention (Industrial Application Field) This invention is applied to polishing and corrosion work performed as a pretreatment when observing the microscopic structure of Ti (titanium).
This relates to the polishing and corrosion method of i.

(Prior art) In recent years, Ti has been used as a lightweight, high-strength, high-corrosion-resistant material.
and Ti alloys (hereinafter simply referred to as rTrJ) are attracting attention, and the adoption of Ti is increasing particularly in the fields of aerospace equipment and chemical equipment.

When using Ti, it is often necessary to observe the WJ microstructure, but at this time, polishing and
After corrosion is performed, microstructures such as grain boundaries are often observed.

Conventionally, when polishing and corroding Ti, for example, in the polishing process, the Ti specimen was first polished with coarse abrasive paper (approximately 9120) and then sequentially polished with fine abrasive paper (#240 →
400 degrees), then polished with diamond paste, then polished with fine abrasive, and then in the corrosion process [11F (IOC) +HNO3 (12C
C) +H20 (87 cc)] Corrosion was performed using a corrosive solution, and the structure was then subjected to observation.

However, in the conventional polishing φ corrosion method for Ti, after ωr polishing, the polished surface tends to have many scratches and distortion patterns, which may make it unsuitable as a test piece. In addition, conventional corrosion methods tend to form a film on the corroded surface and cause uneven corrosion on the speculum surface, so it takes a lot of time to observe the structure afterwards and the corroded structure is unclear. There was a problem in that tissue observation could not be performed well in some cases.

(Purpose of the Invention) This invention was made by focusing on the above-mentioned conventional spotting point, and there are almost no scratches or distortion patterns on the polished surface after polishing a Ti specimen, and there is no corrosion after corrosion. It is an object of the present invention to provide a method for polishing and corroding Ti, which reduces the occurrence of coatings and corrosion unevenness on the surface and allows for extremely good observation of the structure of Ti.

(Structure of the Invention) The method for polishing and corroding Ti according to the present invention is for polishing and corroding a Ti specimen and providing it for microstructural observation.

After polishing the Ti specimen with a fine-grained abrasive, the specimen is immersed in a [HF + H20] solution and then finished polished with a fine-grained abrasive, or while being washed by supplying a [HF + Il, 01 solution] Finish polishing with fine abrasive,
It is characterized in that it is then corroded in a [HF-1HNO3+H,0] solution.

It goes without saying that the method for polishing and corroding Ti in this invention is not limited to pure Ti, but also includes Ti alloys.

t) After forming the Ti described in 1j into a predetermined specimen shape, the obtained Ti specimen is divided into appropriate stages and sequentially coarsely polished.
Change from ff paper to fine abrasive paper and polish.

Next, diamond grains (for example, about 4 to 8 pLm)'
: <Irt' consisting of base material containing hard particles of S
After polishing with J: polishing agent, alumina (for example, 0.05
~0.1 ILm) fine particles/ll including fine particles such as fine particles
Polished with F abrasive, then the sample was polished with IF 4-
Clean and finish polish the polished surface by immersing it in E1201 liquid and then polishing with a fine abrasive, or by polishing with a fine abrasive while supplying the [HF+11.0] liquid. do. This [HF+H20J
As a liquid, [(47%) HF (lcc) +H
It is more desirable to use one with a component base of 20 (10 to 20 cc)].

That is, if the amount of H2O is too large, the HF concentration will decrease and it will be difficult to clean the polished surface, and if the amount of H2O is too small, the HF concentration will become too high and may make the grain boundaries unclear. This is because there is.

In this way, the Ti specimen is immersed in the [HF+H20] solution to remove dirt on the polished surface of the Ti specimen, remove the film formed on the polished surface, and then remove fine alumina (e.g. 0.05 Finish polishing is performed using a fine-grain abrasive containing abrasives such as Alternatively, the Ti specimen is polished with a fine abrasive while the [HF+H20] solution is dripped or flowing onto the Ti specimen, and the final polishing is performed simultaneously with the removal of dirt and film on the polished surface.

Next, in the corrosion process, corrosion is carried out using a [HF+HNO3+H20] solution, but more preferably, the electric power production is slightly higher than that of the conventional one [(47%) 11F (Ice) + (
69%) HNO3 (12cc) + 11.0 (50~60
cc)] It is more desirable to use a liquid.

In other words, if the amount of H2O is too large and the concentration of the corrosive solution is low, uneven corrosion tends to occur on the corroded surface;
This is because if the amount of O is too small and the concentration of the corrosive solution is high, corrosion may become excessive and the grain boundaries may become unclear.

(Example) Using pure Ti as a specimen, the Ti specimen was #120 paper →
#240 paper→#400 paper polishing with 11M1 abrasive paper, then fine grain diamond (6
After performing rt+t polishing with baset containing IL), polishing was performed with a fine abrasive containing fine particles of alumina (0.06 #L). Next, the Ti specimen was heated to [(47%) HF
(ICC) +H70 (10 to 20 cc)] After being immersed in a liquid for several seconds, final polishing was performed using a fine alumina abrasive.

Then, [(47%) HF (lcc) + (69%)
HNO3 (12CC), +H20 (50~60cc)
] The polished surface was corroded by the liquid. The metal structure of the corroded surface obtained here is shown in FIG. As shown in Figure 1,
The resulting corroded surface has no uneven corrosion, and grain boundaries are clearly visible.

(Comparative Example 1) Using pure Ti as a specimen, the specimen was 9120 paper → #2
Polishing was performed using abrasive paper in the order of #40 paper → #400 paper, then polishing was performed using a paste containing fine diamond particles (6L), and then alumina (o, oeIL) was used.
) Polishing was performed using a fine abrasive. The polished surface obtained here is shown in FIG. As shown in FIG. 2, when cleaning with HF+H2O1 liquid was not performed during the polishing process, scratches and distorted patterns were observed on the polished surface.

(Comparative Example 2) Using pure Ti as a specimen, the Ti specimen was #120 paper →
Polishing was performed using abrasive paper in the order of #240 paper → #400 paper, then polishing was performed using a paste containing fine diamond particles (6L), and then alumina (0.06L) was used.
g) Polishing was performed using a fine abrasive containing fine particles. Next, the Ti specimen was heated to [(47%) H,F (Icc) +H
20 (1 O ~ 20 cc)] After being immersed in the solution for several seconds, finishing was performed using a fine alumina abrasive.

Then, [(47%) HF (lcc) + (69%)
HNO3' (12CC) +H20 (87CC)]
The polishing surface was corroded by the liquid. . The corroded surface obtained here is shown in Figure 3. As shown in FIG. 3, the corrosion surface obtained had large corrosion unevenness, which was not a very desirable result.

(Effect of emission) As described above, according to the Ti polishing and corrosion method of the present invention, when a Ti specimen is polished and corroded and subjected to microstructure observation, the Ti specimen is subjected to fine-grain polishing. After polishing with a polishing agent, the specimen is immersed in a [HF+H20] solution and then finished polished for 1f with a fine abrasive, or
, O] Finish polishing is performed using a fine abrasive while supplying a liquid,
After that, the corrosion is carried out in the [HF + HN O3 + H20] solution, so that after polishing the Ti specimen, no scratches or distortion patterns are produced on the polished surface, and no film or corrosion is formed on the corroded surface after corrosion. There is almost no unevenness, and the grain boundaries are clearly visible on the microscopic surface, making it possible to observe the structure of Ti and Ti alloys easily, accurately, and in a short time. It has an extremely excellent effect.

[Brief explanation of drawings]

Fig. 1 is a metallographic micrograph of a polished surface obtained in an example of this invention, Fig. 2 is a metallographic micrograph of a polished surface obtained in Comparative Example 1 of this invention, and Fig. 3 is a metallographic micrograph of a polished surface obtained in Comparative Example 1 of this invention. 3 is a metallographic micrograph of a corroded surface obtained in Comparative Example 2. Patent applicant: Daido Steel Co., Ltd. Representative patent attorney: Yutaka Oshio

Claims (1)

[Claims] (1) When polishing and corroding a Ti specimen for microstructural observation, the Ti specimen is polished with a fine abrasive, then immersed in [HF+H20] solution, and then finished polished with a fine abrasive. Or polish with fine abrasive while supplying [HF+H20] solution, and then polish with [HF+H20] solution.
+HNO3+H20] A method for polishing and corroding Ti, which is characterized by corroding in a liquid.