Investigation of Strength Limit and Synthesis of Materials with the Help of Hypersoniclaunchers pra-0100

Full Title Investigation of the Strength Limit of Several Materials (Ceramics) and Synthesis of Materials Under Very High Pressures, with the Help of Hypersonic Macrobody Launchers Tech Area / Field

• MAT-SYN: Materials / Materials Synthesis and Processing

Brief Description of Technology The investigation of the dynamic characteristics of materials at high loading velocities is of great scientific and practical interest. The main problems which must be solved are:

1. Experimental determination of the theoretical amount of strength in several types of ceramics:

It was difficult to determine this important quantity, because of difficulties connected to the loading of ceramic materials at velocities of 5-15 km/sec. For the determination of theoretical strength, the shock wave velocity in the material must be higher than the velocity of crack propagation. The velocity limit of crack propagation in ceramics is about 5 km/sec, which is why material loading must be carried out at velocities of 7-10 km/sec. The dynamic strength parameters under these conditions can only be measured with the help of the interferometer method, because at present there are no calibrated pressure gauges for these pressures (1-10 TPa). (The shock wave-front lasts for fractions of nanoseconds).

2. Processing maps for materials subjected to impact loads in velocity ranges of 5-15 km/sec.:

Investigations carried out at the PTI of A.F. Ioffe show the possibility of calculating the dynamic strength of materials at the given loading velocities, based on a special methodology for the re-calculation of low-speed loading. Presently, there are only several tests for the experimental verification of calculation methods for certain materials, and only for several discrete loading velocities. It is very important to carry out these investigations in order to obtain important information on equations of the state of materials at extremely high pressures, and for applied investigations on the calculation of the strength of materials at given collision velocities.

3. Synthesis of materials under extremely high pressures:

These loading conditions create the unique possibility for the production of highly solid materials, because the short-time character of loading excludes the possibility of relaxation of local strengths. Dr. T. Sekine is carrying out the same investigations in Japan. He uses plane strikers accelerated up to velocities of 10-30 km/sec, and a laser for loading.

4. The creation of carbon-containing materials and nanomaterials is of great scientific and practical interest. It is necessary to use extremely high loading velocities with a steep-front and back-front compression pulse for both classes of materials.

The above processes are characterized by the strong non-equilibrium state of the material and require the application of special diagnostic methods for the speed processes.

Thus, combining the methods for the high-speed loading of materials in velocity ranges of 3-15 km/sec with contemporary diagnostic methods for speed processes makes it possibility to carry out a complex of unique investigations.

Legal Aspects None.

Special Facilities in Use and Their Specifications Works will be carried out on the test-bench of the IPE RAS. This test-bench is used for the hyperspeed acceleration of macrobodies. It has 4 electric discharge launchers, which allow to accelerate bodies with mass of 10-20 g to up to 6 km/sec. In order to obtain the velocities necessary for these investigations (10-15 km/sec), an additional accelerating stage is being created. This additional stage will carry out the acceleration of bodies with a mass of about ~1 g with a multiplication coefficient of 2.0-2.5. There are two powerful power source- capacitor banks for 6 MJ and 10 MJ. The test-bench has various control equipment, including highspeed photorecording, spectrometers and interferometers of the Doppler type etc.

Presently, there are only several scientific centers in the world where the measurement of the non-equilibrium state of materials at impact loading is possible. The dispersion of mezoparticle speed (0.1-10 m), measured on a real time scale, is the most informative characteristic of the kinetics of microstructure. This diagnostic method is being studied at the Institute of the Problems of Machine Science RAN (Russia). It is based on the combination of laser interferometry with the ensuing microstructure analysis of specimen by methods of optic and electron microscopy. The second experimental method is highspeed roentgenography, carried out at the PTI of A.F.Ioffe. It is proposed that P.G. Rutberg and Yu.I. Mescheryakov will take part in the experiments.

Scientific Papers V.A. Kolikov, A.A. Bogomaz, A.V. Budin, A.G. Kuprin, P.G. Rutberg, Investigation of processes which take place in hydrogen at high initial density heating in powerful electric discharge launchers. Proceedings of the Fifth European Symposium on Electromagnetic Launch Technology. April 10-14, 1995. Toulouse, France. Paper 41.

P.G. Rutberg, A.V. Budin, V.A.Kolikov. Comparative analysis of the characteristics of electric discharge launchers in terms of the effects on hydrogen and nitrogen. Proceedings of the Fifth European Symposium on Electromagnetic Launch Technology. April 10-14, 1995. Toulouse, France. Paper 46.

F.M. Andreev, Yu.I. Mescheryakov, S.A. Atroshenko, N.I.Zhigacheva. Shock-wave compactation of amorphous magnetic-soft powders. Letters to the Journal of Technical Physics, v.21, N14.

Yu.I. Mescheryakov, N.A. Makhutov, S.A. Atroshenko. Macromechanisms of the dynamic fracture of ductile high-strength steel. Journal of the Mechanics and Physics of Solids, v.42, N9, 1994.

V.A.Kolikov, P.G. Rutberg, A.V. Budin, A.A. Bogomaz. Hypervelocity electric discharge accelerators. Proceedings of the Eight Symposium on Electromagnetic Launch Technology. April 21-24, 1996, Baltimore, Maryland, USA.