JPH027028B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to non-destructive testing of various materials, structures, etc.
That is, it relates to a couplant for ultrasonic flaw detection or thickness measurement. More specifically, it is a rust preventive for ultrasonic flaw detection or thickness measurement that is made of an aqueous liquid containing a carboxyvinyl polymer and a nonionic surfactant and has excellent thixotropic properties and easy handling, and has excellent ultrasonic transparency. Concerning sex couplants. [Prior art] In ultrasonic flaw detection and ultrasonic thickness measurement, which are types of non-destructive testing, ultrasonic pulses are sent from the surface of the specimen to the inside to detect interfaces, scratches, lattice defects, etc. The reflected waves are converted into electrical signals and transmitted to a cathode ray tube, which allows us to determine the thickness of the sample, the presence, location, and size of scratches and defects inside the sample. Conventionally, in order to eliminate the air gap between the transmitting and receiving surfaces of the ultrasonic oscillator and the sample being tested, and to reduce the amount of attenuation of the transmitted waves, measurements were performed using a couplant such as oil, glycerin, or water. was doing.
However, due to the low viscosity of oil, glycerin, and water, when used in flaw detection methods that produce gaps, such as automatic flaw detectors, it is difficult to obtain a sufficiently thick couplant layer, and There are drawbacks such as sagging when performing flaw detection. Recently, couplants mainly composed of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) have been developed to improve the disadvantages of oil, glycerin, and water.
A couplant consisting of an aqueous liquid containing . [Problems to be Solved by the Invention] All of these couplants still become sticky and sag, and furthermore, at high temperatures, gelation and solidification occur, making it impossible to work for a long time, which is a new drawback. ing. Moreover, when conventional couplants are used, even if they are wiped off after use, rust will form after several hours or days, deteriorating the non-tested sample. The present inventors have conducted intensive research to improve the above-mentioned drawbacks and to create a couplant with excellent ultrasonic permeability. As a result, an aqueous liquid containing a carboxyvinyl polymer and a nonionic surfactant has been developed. The present invention was completed based on the discovery that it can be used as a couplant for non-destructive testing having the following characteristics. [Means for Solving the Problems] The anticorrosive couplant for nondestructive testing of the present invention can be obtained by mixing and stirring water, a carboxyvinyl polymer, and a nonionic surfactant. [Function and Examples] The amount of carboxyvinyl polymer blended varies depending on the desired viscosity, but usually 100 parts of water (parts by weight,
0.1 to 25 parts, preferably 0.2 to 25 parts (same below)
10 parts, particularly preferably 0.3 to 5 parts. The couplant of the present invention has thixotropic properties, and when applied to vertical surfaces or ceiling surfaces, it usually
The precipitation value at °C is 98dyne/ ^cm2 or more, especially 118
~700 dyne/cm ² and a drop value at 70° C. of 98 dyne/cm ² or more, particularly preferably 107 to 665 dyne/cm ² . As a carboxyvinyl polymer, the molecular weight is
1,000,000 to 3,000,000 is used, and may also be used in the form of its ammonium salt. Specific examples include Carbopol (trade name) 934, 941, 940, 960 manufactured by BFGoodrich Chemical;
Examples include 961. The nonionic surfactant blended into the couplant of the present invention serves to suppress the occurrence of rust. Furthermore, the viscosity and thixotropic properties are not lost. And it does not gel. This effect cannot be obtained with other anionic or cationic surfactants. The amount of nonionic surfactant added is usually 0.1 to 15 parts per 100 parts of water.
parts, preferably 0.3 to 10 parts, particularly preferably 0.7 parts
~7 parts. Preferred nonionic surfactants include ether type nonionic surfactants such as polyoxyalkylene alkyl ether, ether ester type nonionic surfactants such as polyoxyethylene glycerin fatty acid ester, and ester type nonionic surfactants such as polyethylene glycol fatty acid ester. Examples include nonionic surfactants and nitrogen-containing nonionic surfactants such as cycloalkylamine ethylene oxide. Although the couplant of the present invention is water-based,
Especially when good ultrasound transparency is required,
Furthermore, glycerin may be added. When blending glycerin, 20 to 1100 parts of glycerin, preferably 68 to 1050 parts, per 100 parts of water.
part, 0.1 to 25 parts, preferably 0.2 to 10 parts of carboxyvinyl polymer. Furthermore, if necessary, preservatives, neutralizing agents, etc. may be added as appropriate. The couplant of the present invention may be applied to the surface of a sample to be inspected using a brush, spatula, or the like. A major feature of the couplant of the present invention is that it has thixotropic properties. In other words, conventional couplants have a relatively low viscosity and can be spread freely with a brush, but on the other hand,
When applied to a ceiling surface, etc., it flows and sag occurs, making it impossible to obtain the desired film thickness. However, since the couplant of the present invention has thixotropic properties, it cannot be applied to any area. It does not sag even when applied to a surface, and can be easily applied with a brush, making it possible to obtain a couplant film whose thickness does not change over time. Another feature of the couplant of the present invention is that it does not gel or solidify even at high temperatures, and therefore does not cause any trouble in flaw detection work. During flaw detection work under the scorching sun, the objects being tested, such as steel pipes, quickly reach temperatures of over 70°C, and conventional couplants whose main ingredients are PVA or CMC immediately gel or solidify and no longer function as intended. However, since the couplant of the present invention does not gel or solidify even at such high temperatures and does not sag, work at high temperatures can be carried out as easily as at room temperature. Furthermore, since it does not solidify even at low temperatures (-20°C), it can be used in an extremely wide temperature range. Yet another feature of the present invention is that the sample to be inspected does not rust after use. Therefore, post-processing after use is extremely simple and only requires wiping with a cloth. In addition, the couplant of the present invention has good wettability on the surface of the non-inspected object, is not repelled like water or glycerin even if there is an oil film, and has good sliding properties on the probe, making flaw detection easy. In particular, glycerin-based materials have many excellent properties, including excellent ultrasound transparency. As described above, the couplant of the present invention can be advantageously used in manual, semi-automatic, or automatic ultrasonic flaw detection or thickness measurement, and can perform an excellent function as a couplant in any location or work environment. Moreover, it does not leave any problems after use, and can exhibit outstanding effects in non-destructive testing. Next, the couplant of the present invention will be explained with reference to Examples and Test Examples. Examples 1 to 10 The couplant of the present invention having the composition shown in Table 1 was prepared, and the viscosity (20°C) of the couplant obtained,
The yield values at 20°C and 70°C were investigated. The results are shown in Table 1. Comparative Examples 1 to 8 Comparative couplants having the compositions shown in Table 1 were prepared, and the viscosity (20°C) of the couplants obtained,
The yield values at 20°C and 70°C were investigated. The results are shown in Table 1.

【table】

[Table] As shown in Table 1, the couplant of the present invention has high viscosity and high yield values at 20°C and 70°C, indicating that it has excellent thixotropic properties. Test Examples The following tests were conducted using the couplants prepared in Examples 1 to 10 and Comparative Examples 1 to 8, respectively. (Sagging test) After applying each couplant to a thickness of 1 mm on a part of a steel plate, the steel plate was stood vertically and the surface of the steel plate was
The time required for the material to sag and fall was measured. This test was conducted at two different temperatures: 20°C and 70°C. The results are shown in Table 2. Further, in the same manner as above, each couplant was applied to a steel plate at 20°C, and then the steel plate was turned upside down to examine the state of the couplant on the ceiling surface. The results are shown in Table 2. (Sensitivity test) Each couplant shown in Table 1 was applied to a thickness of 0.3 mm on a 13 mm thick steel plate (100 mm x 200 mm) having the surface roughness shown in Table 2, and ultrasonic flaw detection was performed. Sensitivity was measured (5 MHz in the vertical direction) using an FD-210 (manufactured by Mitsubishi Electric Corporation). The evaluation is based on the sensitivity when the bottom echo height is 80% when using glycerin, which is said to have excellent ultrasound transparency (zero).
We investigated the sensitivity (-dB) required to achieve the same bottom echo height (80%). The results are shown in Table 2. (High-temperature treatment test) Each couplant shown in Table 1 was held at 70°C for 30 minutes, and the state of gelation (solidification) was examined. The results are shown in Table 2. (Slip property test) Each couplant shown in Table 1 was applied to a thickness of 0.3 mm on the surface of a steel plate with a surface roughness of 20 μm, and the slip property of the probe was examined. The results are shown in Table 2. (Rust prevention test) Flat steel plate (Surface roughness 50μm by shot blasting)
Each couplant shown in Table 1 was applied to a thickness of 0.5 mm,
The specimens were left for 14 days (at 40°C and 100% humidity in a constant temperature bath), and the number of days until rust appeared was observed. The results are shown in Table 2.

【table】

[Table] As is clear from Table 2, the couplant of the present invention does not sag no matter where it is used, does not sag or gel even at high temperatures, and has an anti-rust effect. Furthermore, it has excellent ultrasonic transparency and flaw detection workability.

Claims (1)

[Scope of Claims] 1. A couplant for non-destructive testing consisting of an aqueous liquid containing a carboxyvinyl polymer and a nonionic surfactant. 2. A couplant for nondestructive testing consisting of an aqueous glycerin liquid containing a carboxyvinyl polymer and a nonionic surfactant.