Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

electrostatic diagnostics, body destruction, micro-particles, electric charging, electron gas in metals, double electric layer

1. Vatazhin A. B., Golentsov D. A., Likhter V. A., Shul’gin V. I. Problem of contactless electrostatic aircraft engine diagnostics. Theoretical and laboratory modeling / Izv. RAN. MZhG. 1997. N 2. P. 83 – 95 [in Russian].

2. Bozhkov A. I., Vatazhin A. B., Golentsov D. A., Likhter V. A. Electric fields, produced by aircraft engine jets. Theoretical and laboratory modeling / Aйromekh. Gaz. Dinam. 2003. N 2. P. 49 – 59 [in Russian].

3. Vatazhin A. B., Ulybyshev K. E. Model of formation of the electric current in aircraft jet engine ducts / Izv. RAN. MZhG. 2000. N 2. P. 139 – 148 [in Russian].

4. Landau L. D., Lifshits E. M. Theoretical physics. Vol. 4. Statistical physics. — Moscow: Nauka, 1964. — 567 p. [in Russian].

5. Theory of the inhomogeneos electron gas / S. Lundqvist, N. March (ed.). — Moscow: Mir, 1987. — 400 p. [in Russian].

6. Babichev A. P., Babushkina N. A., Bratkovskii A. M., et al. Physical quantities: reference. — Moscow: Йnergoatomizdat, 1991. — 1232 p. [in Russian].

7. Maxwell J. C. A Treatise on Electricity and Magnetism. — Dover, 1873. — 266 p.

8. Rawlins A. D. Note on the Capacitance of Two Closely Separated Spheres / IMA Journal of Applied Mathematics. 1985. N 34(1). P. 119 – 120.

9. Smythe W. R. Static and Dynamic Electricity. — NY: McGraw-Hill, 1950.