SU1675756A1 - Method of non-destructive testing of dielectric material products - Google Patents

Abstract

This invention relates to acoustic methods of non-destructive testing. The aim of the invention is to increase the sensitivity of the control by providing the appearance of closed pores due to the formation of an alternating electric field, the intensity of which allows gas-discharge processes to be excited in them. The product 5 is placed between the plates of the capacitor 1 of the high-voltage power supply unit 2 to the capacitor 1 is supplied with a voltage that forms in the product 5 a uniform alternating electric field with a maximum strength of not less than 0.9 the strength of the sample of the product 5. initiating acoustic oscillations, which are accepted by transducer 3. Information processing unit 4 makes it possible to measure the parameters of 3 vibrations received by the transducer and make a conclusion about the presence of pores 6 in and Zdeli 5. 1 Il. THX

Description

V

l

T

about xj

ate

Os

The invention relates to acoustic methods of non-destructive testing and can be used in the inspection of products made of dielectric materials.

The purpose of the invention is to increase the sensitivity of monitoring by providing the detection of closed pores due to the formation of an alternating electric field, the intensity of which allows gas-generating processes to be excited in them. The drawing shows the scheme of implementation of the method of non-destructive testing of products from dielectric materials.

The method of non-destructive testing of products made of dielectric materials is implemented using a capacitor 1, connected to a high-voltage power supply unit 2, and an acoustic transducer 3, connected to the information processing unit 4. Position 5 in the drawing indicated a controlled product, the position of the 6-pores in the product 5.

A method of non-destructive testing of products made of dielectric materials is as follows.

A uniform alternating electric field is formed in the product, the maximum intensity of which is not less than 0.9 the intensity of the breakdown of the material of the product. Acoustic oscillations propagating in the product are received and their parameters are measured. The measured parameters of the received vibrations determine the presence of defects in the product.

The method of non-destructive testing of products made of dielectric materials is implemented as follows.

A controlled article 5, for example a quartz plate, 2 mm thick, is placed between metal square (15x15 mm) plates of a capacitor 1 connected to a high-voltage power supply unit 2, providing an output sinusoidal voltage of up to 5 kV and a frequency of up to 20 kHz. On the surface of the product 5 have an acoustic transducer 3, for example a piezoelectric. From the power supply unit 2, the capacitors 1 are supplied with a voltage sufficient to form in the product 5 a uniform alternating electric field with a maximum strength of 0.9 times the strength of the breakdown of the product material, i.e., about 105 V / cm. If there are gas pores 6 in the product 5, ionization occurs in the latter, which leads, due to the heating of the gas cavity, to a sharp increase in the gas pressure in it and, accordingly, to the oscillations of the walls of the pore 6, propagating in product 5

elastic vibrations. The acoustic oscillations initiated by the gas discharge process are received by transducer 3 and fed to information processing unit 4, for example, a standard instrument for measuring the parameters of acoustic emission signals. Parameters of received oscillations, for example, the intensity of signals of a large amplitude, are measured by block 44, and the presence of defects in the product 5, in particular, pores 6, is determined by them. The controlled product 5 is moved between the plates of the capacitor 1 and thus monitored the entire volume products 5.

5As a result of recombination processes

Charged particles on the pore walls, the value of the intensity of the breakdowns in gas pores is about an order of magnitude greater than the value of the intensity of the breakdown of gases for flat wide interelectrode gaps and does not exceed 0.9 times the intensity of the breakdown of solid dielectrics. Because with a pressure of less than 1 mm. Hg Art. gas discharge processes are absent, and ultrahigh

5 the pressure in the pores is impossible according to the technology of production of dielectrics, then in the specified range of gas pressure in the pores the application of voltage to the plates of the capacitor 0.9 voltage of the sample of the controlled dielectric reliably provides ignition of the gas discharge in the pores. In gas-discharge processes, the main part of the energy of the electric field is released on the pores; therefore, the acoustic oscillations initiated by this process significantly exceed the amplitude of the acoustic oscillations due to the electrostriction of dielectric materials. For these reasons, the detection of pores is effective even in the presence of interfering factors, such as foreign inclusions, which may not represent a danger from the point of view of technology, but contribute to the occurrence of electrostriction. Way

5 non-destructive testing of products from dielectric materials provides detection of closed pores with a diameter of more than 0.1 mm. When testing products made of transparent dielectric materials, for example, from

Claims (1)

0 quartz glass, the fixation of acoustic oscillations is accompanied by the ignition of a pulsating gas discharge, which is clearly visible in the dark. Invention Formula 5The method of non-destructive testing of products made of dielectric materials, which consists in forming an alternating electric field in the product, receiving acoustic oscillations propagating in the product, measuring a pair the meters of the received oscillations and by them the definition of the formed in the product is uniformly shared by the presence of defects in the product, about one of the native alternating electric field in view of the fact that, in order to increase, the choice is not less than 0.9 sensitivity, for example, the maximum material