The plasma surface hardening, as one of methods of surface treatment by heating sources with high power density, finds presently wide and effective application in conditions of short-series and single-part (including repair), and large-scale and wholesale manufacture. One of effective methods for research and optimization of the plasma surface hardening is the use of computer simulation. The complex mathematical model of steel parts hardening at high-speed plasma heating is presented in the article. Model includes mathematical description of steel parts heating and cooling, and also forming of their stress-strain state. The distinctive feature of the presented model is taking into account under modeling of phase transformations and plastic deformations. It allows to achieve the maximally adaptation of the simulation results to real physical characteristics of the process. The algorithm of model computer realization, based on the application of final elements method is offered.

In this paper, the authors use computational tools to simulate thermal and mechanical processes involved in plasma spraying that lead to crack formation and delamination. The substrate-coating system is represented by a metal strip (120 x 20 x 2 mm) and a ceramic layer with a thickness of 0.06 mm. The transient heat transport problem and stress-deformation state of the 3D sample is solved via stress relaxation due to plastic deformation and distributed displacements or cracking. Paper includes a German-language abstract.

Integrated technological complex for computer simulation, experimental study and practical realization of plasma spraying processes was created. Main features of development are possibility of simulation of all plasma spraying stages (moving and heating particles in plasma jet, coating structure formation, heat transfer and strained-stress state of coating-substrate system) separately and in the mode of end-to-end; data base with material and gas properties; possibility of experimental measurement of main plasma spraying parameters and entering them in the computer in the real time mode; graphic visualization of simulation and experimental measurement results; computer control of plasma spaying equipment; fabrication of initial lots of products according to developed technology. Complex is designed on the base of VPS «Plasmatechnik» equipment. Experimental measurement of particle temperature, velocity and coating temperature were conducted with original optoelectronics system. All technological and measurement equipment are connected with computer with special interfaces and working under computer control.

Mathematical and computer models of movement and heating of particles in low pressure conditions are developed. The mathematical models are based on the molecular-kinetics theory of gases. A program complex for computer realization of models is developed. It contains a built-in data base of temperature dependent properties of substances, system of processing and graphic visualization of simulation results. For verification of the developed models, computer simulation and experimental measurements of Al2O3 particle temperature and velocity are conducted. These materials were sprayed with Plasma-Technik equipment at pressure 60 mBar in argon. Particle velocity was measured with a special optical device, particle temperature was defined by intensity radiation method. It was established that the developed models are adequate to real process (error of 5-8 %) and may be used for study and improvement of VPS processes.

In this paper, the flattening and the simultaneous solidification of a liquid particle when it hits a solid surface are described mathematically and numerically simulated in cylindrical coordinates on the basis of the Navier-Stokes equations. The heat transfer in the particle and in the substrate is simulated by solving the 2-D heat conduction problem, whereby hydrodynamic processes in the melted particle as well as pressure forces are taken into account. The particle solidification is investigated using the one-dimensional Stefan problem, taking into account the contact heat conduction at the boundary between particle and substrate. For numerical calculations, computational algorithms were created on the basis of the difference method, which were implemented in the form of an applied program complex. Paper includes a German-language abstract.

In this paper, a comprehensive mathematical model is developed for the integrated simulation of the coating plasma spraying process under low pressure. This simulation models powder particles that are heated and moved in a plasma jet, the heat transfer in the "coating substrate" system, and the formation of thermal loads. Basic software is developed for the practical implementation of the model. The process of alumina spraying is simulated. Paper includes a German-language abstract.

The main purpose of this work is the development of mathematical and computer models for the integrated simulation of all stages of the atmospheric plasma spraying process (APS) with temperature dependent thermophysical and mechanical properties of the used materials and gases and experimental verification of the simulated results. The following mathematical models of APS were created: particle heating and movement in the plasma jet; coating structure formation; heat transfer and residual stresses in the coating-substrate system. The computer realization of these models enables us to model all stages of APS (integrated or separately). Databases of coating, substrate and plasma-gas substances include the temperature dependent properties. The model of APS is divided in 3 parts, which are connected by continuous data interface. Two dimensional approximation of plasma-gas velocity and temperature in the free plasma jet was used for computation of particle velocity, trajectory and temperature. This information was created with a special Graphic program module and included in database. Computer experiments for plasma spraying of Ah03 and ZrO 2 +8%Y 2 O 3 in Ar/H 2 plasma were carried out. The experimental verification of developed models with High-Velocity-Pyrometry (HVP) and Laser-Doppler-Anemometry (LDA) have shown the satisfactory precision of simulated results.

On the base of gases molecular and kinetic theory a mathematical model of interaction between powder particles and plasma jet is developed. Three-dimensional description of plasma forming gas density distribution as well as particle motion in the plasma jet are a characteristic property of the model. A software for practical realization of the mathematical model is created. Said software provides the possibility to investigate an effect of low-pressure plasma spraying parameters on particle velocity and coordinates in the plasma jet. Computer simulation of particle velocity for powders from aluminium and tungsten oxides in argon plasma under 60 Mbar is conducted. A "Plasma-Technik" VPS unit is used for testing the developed model. Particle velocity measurement is made by a specially developed optical-electronic unit.