RU2359245C1 - Method of determining cavitation wear resistance - Google Patents

Abstract

FIELD: instrument engineering.

SUBSTANCE: use: for determination of cavitation wear resistance. Essence of invention: cavitation field is created with the help of ultrasonic sound in liquid medium where there is uniform effect at microslice surface of tested material. Differential estimation of cavitation wear resistance of tested material different areas is performed with the aid of instrument methods allowing to perform quantitative estimation of different materials wear resistance. Differential estimation is expressed in wear resistance relative value: ε=Δh_r/Δh_n, where Δh_r - wearing depth of microslice reference area, Δh_n - tested area wearing depth.

EFFECT: provision of differential estimation of different layers and material structural elements wear resistance subjected to cavitation.

3 cl, 1 dwg

Description

The invention relates to techniques for studying solid materials for cavitation resistance using ultrasonic waves.

There are various methods for studying the cavitation resistance of materials. The largest number of proposals relates to the use of various types of test objects, both mechanical and chemical.

A known method to evaluate the shape and intensity of the cavitation area by the destruction of the polished surface of the glass plate and the destruction of the photosensitive photographic layer [1].

There is also a method for determining cavitation resistance by a specially developed device in which the total area of holes formed in an aluminum foil subjected to cavitation is measured using a photocell [2].

The closest in technical essence method of assessing cavitation resistance, where the weight loss of an aluminum cylinder (2 × 2 mm ^{2 in} size) was measured, placed in the focal spot of a concentrator operating at a frequency of 513 kHz. The cylinder was exposed to cavitation at various electric voltages at the concentrator and a constant scoring time (5 min). Moreover, the decrease in cylinder weight ΔG, obtained as the difference in weight before exposure to ultrasound and after exposure, was taken as a measure of the effect of shock waves of cavitation bubbles [3].

The disadvantage of the above methods is that they require a lot of time, considerable laboriousness in irradiating and weighing the samples, which reduces the accuracy of the obtained experimental data due to instrumental errors, and also shows an insufficiently objective picture of the destruction of the surface of the test sample.

The objective of the invention is to provide a method that provides a differential assessment of the wear resistance of various layers and structural components of a material subject to cavitation.

To achieve this goal in a liquid medium under the action of ultrasound, a stable cavitation field is created, exerting a uniform effect on the test material, after which a differential assessment of cavitation wear resistance is performed using various instrumental methods, namely:

 using recording and analysis of profilograms;

 electron microscopy;

 interferometry.

As is known, for mechanical failure, certain values of mechanical stresses or deformations that exceed thresholds are required. In this case, mechanical stresses are determined by the pressure of the shock wave, and it, in turn, depends on the peak power carried by this shock wave.

In the proposed method, the work intensity is determined by the parameters of the ultrasonic magnetostrictive generator with the radiation power (power density), vibration frequency, distance h between the generator working surface and the sample surface, as well as the main physical and chemical parameters of the working medium (viscosity, density, etc.). Qualitative and quantitative assessment of the parameters of cavitation wear resistance as a result of tests was carried out using instrumental methods by simultaneously comparing the worn layer in depth. In this case, the analysis of the zone of the test sample was carried out by recording on a profilograph-profilometer. A quantitative assessment of the wear resistance of dissimilar materials is expressed as a relative indicator of wear resistance

- глубина износа эталонной зоны микрошлифа,Where

- the depth of wear of the reference zone microsection,

- глубина износа исследуемой зоны.

- Depth of wear of the studied area.

Thus, it is possible to simulate various wear mechanisms, taking into account the wide range of regulation of the parameters of the emitter and the location of the sample.

The drawing shows a diagram of an experimental setup for research and testing of the proposed method.

The method is implemented on the installation, including:

 ultrasonic generator (1) (UZG), UZDL-1 ultrasonic magnetostrictive disperser with a frequency of 22 kHz and a radiation power of 4-5 W was used as a UZG

 working fluid (2), which can be used as water, various lubricating, corrosive and chemically active fluids that simulate the working conditions of the tested materials, close to the actual working conditions of the mechanism. In this case, tap water was used as the working fluid,

 microsection (3), the test material in the form of a section (3),

 capacity (4) in which the test material (3), working fluid (2), UZDL-1 (1) are placed.

The proposed method is as follows. A test sample (3) is placed in the working fluid (2) at the bottom of the tank (4). When ultrasonic vibrations are excited in the working fluid using UZDL-1 (1) with a frequency of 22 kHz and a radiation power of 4-5 W, a cavitation field is created.

Mechanical destruction of the surface of the test sample occurs when the bubbles collapse, which give off their energy, primarily in the form of shock waves, which leads to mechanical erosion.

Profilograms were recorded along the length of the hardened (processed) layer and along the initial (unhardened) zone, which was taken as the standard. The analysis of the obtained profilograms allows us to give not only an objective qualitative assessment of the wear resistance of the studied layers, but also quantitatively evaluate (in relative terms) the level of increase (decrease) of this indicator to the initial one. The profile curves thus obtained will objectively reflect the actual actual wear resistance of the surface and inner layers of the test material.

List of references

1. Y. Olaf. Oberflachenreinigung mit Ultraschall. - Akustika, 7, 5, 253, 1957

2. A.E. Crawford. The measurement of cavitation. - Ultrasoning, 2, 3, 120-123, 1964

3. A.S. Bebchuk. On the issue of cavitation destruction of solids. - Acoustics. Journal., 3, 1, 90, 1957 (prototype).

4. Powerful ultrasonic fields. Physics and technology of powerful ultrasound. Edited by prof. L.D. Rosenberg, Moscow: Nauka, 1968

Claims (3)

1. A method for determining cavitation wear resistance, which consists in the action of cavitation on the test area, characterized in that the cavitation field is created using ultrasound in a liquid medium, where the microsection of the material under investigation is uniformly exposed to the surface, and the cavitation wear resistance of different areas of the material under study is differentially evaluated using instrumental methods to quantify the wear resistance of dissimilar materials and express Xia as a relative index of wear resistance: ε = Δħ _e / Δħ _n, where Δħ _e - wear depth reference microsection zone, Δħ _n - depth investigation zone wear. 2. The method according to claim 1, characterized in that the assessment of surface cavitation wear of the material is carried out by recording and analyzing a profilogram, by electron microscopy, by interferometry. 3. The method according to claim 1 or 2, characterized in that the internal layer of the microsection which is not subjected to any kind of processing is adopted as a reference zone.