RU1817016C - Ultrasonic method of determining true value of density of powder material - Google Patents

Abstract

The invention relates to non-destructive means for monitoring and analyzing the properties of a material, mainly isotropic, by acoustic methods. The purpose of the invention is to simplify the method. When implementing the method on two samples of the same size with different real density, the frequencies of resonant ultrasonic vibrations are measured and the true density is determined from the ratio Po -ri - tT-, where / Do is the true density - 2 I f1 - -% - (f fr } material; p pi - real density of samples; fi, f2-frequency of resonant ultrasonic vibrations of samples with densities / 01 and pi, respectively. The method is characterized by simplicity and expressiveness in determining the system density of products of simple shape and small size. 00 s

Description

The invention relates to non-destructive means for monitoring and analyzing the properties of materials by acoustic methods and can be used in powder metallurgy for mass control of the composition and density of articles of small size and simple shape (rod, disk, etc.).

The purpose of the invention is to simplify the method of ultrasonic determination of the true charge of the powder material.

The method is carried out as follows. Make two isotropic

a sample of one size, but with a different density. Their density is measured, for example, by hydrostatic weighing, and then ultrasonic resonance vibrations are excited and frequencies, for example, longitudinal vibrations are recorded, after which the true density of the isotropic material is calculated by the ratio

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ro

fi-fz

OL JL)

(f P2}

where PO is the true density of the material, g / cm:

Р2 Р2 the real density of samples, g / cm3:

fi, frequencies of resonant ultrasonic vibrations of samples with densities pi and pi, respectively, kHz.

An example of a specific implementation of the method. Two ogbrazts from alumina powder A120z were subjected to isostatic pressing at a temperature of T 1500 ° C and a pressure of P 150 MPa for 30 minutes. for the first sample and 10 min. -for the second. The actual density of the samples was measured by the hydrostatic method. For the first sample, it was pi 3.39 g / cm3, for the second - / 32 - 2.58 g / cm3. Before ultrasonic measurements, the samples (40 mm x 5 mm x 5 mm) were ground. The frequencies of the longitudinal resonant vibrations were measured on a SK4-59 spectrum analyzer, and the periods on a frequency meter: Ф 5041. The frequency of ultrasonic vibrations of the first sample turned out to be fi 114.68 kHz (the period of oscillations of Th 8.72 μs), the second - fa 67.34 kHz (T2 14.85 μs). The true density of the powder material from A120z, taking into account f 1 / T, was determined from the ratio

In the same manner, measurements were made on samples of nickel (Ni). The samples had the shape of a cylinder of 0 5 x 40 mm. The first sample was fused and had a hydrostatic density of p of 8.90 g / cm3, and the true one was measured by X-ray, and the method was 8.89 g / cm3. The second, made by special powder technology, had a density of p2 3.71 g / cm3. On the

the described equipment was used to measure the frequencies of the resonant longitudinal vibrations of these samples: fi 69.15 and fa - 18.14 kHz, True density Ni; determined by the proposed relation

ny, turned out to be equal:

PO 8.86 g / cm3.

As can be seen from the examples, the discrepancy between the obtained results and the true density measured by the X-ray method and known from the technical literature is insignificant. With mass control of true density, there is a significant gain in ease of implementation, express ™ and accuracy, not only in comparison with the prototype, but also in the basic (X-ray) method ... ..

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Claims (1)

The claims ro 114.68 -67.34 114.68 67.34 - 4.05 g / cm. 3,59 2,58 Deviation is the value of po. obtained by the proposed method did not exceed 2% compared with the true density measured by the x-ray method and equal to 3.98 g / cm In addition, measurements were made on a third sample, showing a pg of 1.40 g / cm3 and a fs of 29.85 kHz. To determine the true density of the material of the samples, the density and frequency of the first and third, and then the second and third  3.99 g / cm3. The method of ultrasonic determination of the true density of a powder material, mainly isotropic, comprising measuring the frequencies of resonant ultrasonic vibrations of samples of the same material having the same shape and size, depending on the ratio of the mass of the sample to the entire occupied volume (real density), characterized in that, in order to simplify the method, the measurement is carried out on two samples with different real densities, and the true density of the material is determined from the ratio Ro f 1 f2 about iЈ pi lL pi