Shapoval O. Scientific foundations and technologies development for intensive processing of refractory and composite materials

The thesis is aimed at solving an important scientific and technical problem of scientific bases and technologies development for production of refractory and composite materials. An analytical solution to the parallel connection rheological model of a rigid-plastic element (wire) and an element with a series connection from viscous and plastic elements by solving the equations of equilibrium, plasticity and contact friction in the materials separation zone between soft shell and refractory wire and heat exchange equations. Experiments and mathematical modeling have shown that under conditions of drawing with heated wire in a soft shell there are excessive stresses of the material in the soft shell and pressure on the wire material, which can completely separate the two surfaces of the die and wire. The pressure value significantly depends on the taper angle of the inlet part of the drag and has a maximum in the outlet part. Finite element method in the Ansys AUTODYN system simulates the hafnium hot drawing process of in a soft - copper shell, in which the deformations distribution is as follows: the instantaneous copper yield strength reaches the yield hafnium strength and co-deformation of the composite material with metallurgical contact between components by this time the soft shell acts as a lubricating layer A set of technologies and technological equipment for the tungsten and composite wire production, technology for the production the plasmatron electrodes has been developed. The molybdenum wire production technological scheme was developed, experimentally substantiated and realized in the industry. Its main stages are billets cross-screw rolling, vibration drawing with wire blanks induction heating and wire cold drawing with oil hydrodynamic introduction and vibration application to the tool during the process transitional stages. An effective non-destructive method and a device for evaluating the wire billets technological properties with a diameter more than 3 mm depending on the value of the elasticity modulus have been developed. The blanks classification according to the elasticity modulus value to obtain the final product in different diameters ranges while minimizing production costs. The processing technological schemes influence on structure formation the weight wire is studied. The change dependences in the quantitative parameter of the structure estimation – L/W single crystal on the total deformation degree by drawing are obtained. It is established that the use of intensive technologies for pressing and drawing, starting from the coefficient of extraction from the billet 17,5–23,8 allows to achieve L/W > 10.