Surface layer evolution under the external heating

Generalized equation system is written to describe the surface layer evolution under electron beam action. Chemical reactions and porosity evolution are taken into account. The model was used to describe the electron beam treatment of thin layer with varied thickness. The review is made for some previous particular models of electron beam surface treatment with chemical reactions and shrinkage. It was pointed that the model permits the existence of self-sustaining regimes and quasi-stationary technology regimes

Pressure diffusion and chemical viscosity in the filtration models with state equation in differential form

Some options of coupling filtration models are suggested using irreversible state equations in differential form. State equations include explicitly the coefficient of compressibility, coefficients of concentration expansion and other physical properties affecting rheological properties and composition. To construct the models, the improvement of thermodynamic relations is used. New physical factors are introduced with the help of new thermodynamic variables. The chemical viscosity, pressure diffusion and concentration expansion phenomena are taken into account. The simplest particular problems illustrating the role of new effects are distinguished for stationary filtration regime. The revealed nonlinear effects can be important when considering biology liquid flows in porous biomaterials where deviations from classical laws are possible

Cellular automata modeling of microcrystalline structure formation

The paper discusses the problem of microcrystalline structure formation during magnetron sputtering. The authors suggest the model based on cellular automata approach combined with chemical kinetics considerations, briefly discuss a practical way for kinetic constants evaluation and derive their accurate values. The work numerically solves a particular problem of coating formation by magnetron sputter deposition in multicomponent chemically active plasma

Model of layers bonding during LOM-process

The model of LOM-process with chemical reaction in intermediate layer is suggested in this paper. Maximal stress in contact zone and half-thickness of contact area are given from contact problem of mechanics. It was shown that this problem is similar to the problem of different material conjugation using synthesis in solid phase. Dimensionless variables and dimensionless criteria are identical for these processes. The qualitative examples of temperature field evolution for self-sustaining mode are demonstrated

Micro- and macrostresses in two level model of coating growth

In the work, a two level model of coating growing with the diffusion and chemical compounds formation is proposed. The process of coating formation includes different physico-chemical steps and transformations of the structure. From the experiments it was established that the coating consists of the following substances: 4+ titanium oxide, titanium pyrophosphate, calcium pyrophosphate, calcium titanophosphate. Coating growth rate is determined by the deposition rate and the dispersion of the particles suspended in the electrolyte. The processes taking place in the electrolyte itself are not considered. The two levels (level of separate particles and level of macroscopic sample) are connected through the calculation of effective properties and parameters of the reaction. The influence of the model’s parameters on the coating compound’s and the sample’s stress-strain state has been investigated

Two-temperature model of gas combustion in a model burn device of the cylindrical form

The two-temperature model of gas combustion in a porous body of cylindrical heat-generator has been offered and numerically analyzed. Heat exchange between solid frame and gas; burning products interaction with heat-exchanger; distinction of diffusion speeds and heat conductivity in the gas phase are considered in the model. The influence of model parameters on characteristics of stationary modes of gas combustion for various heat exchange conditions of porous torch with heat exchanger is investigated. The results of numerical research do not contradict with observable laws that indicates the opportunity of model use for statement and solving the problem of work optimization of the real burning device

The influence of vacancy generation at the initial stage of ion implantation

The paper presents a coupled isothermal model at the initial stage of a solid surface treatment with particle beams. Mechanical stresses arising due to the interaction of particles with the surface affect the redistribution of the implanted impurity. Vacancies in the metal surface and their generation under stress are also taken into account. The kinetic law is formulated on the basis of thermodynamics of irreversible processes. The authors used numerical investigation methods. As a result, they have obtained the distributions of impurity concentration and deformations for various time moments. The authors also compare the concentration and deformation profiles with and without vacancies and study the influences of some model parameters. The effect of vacancy generation on the diffusion has been established to lead to an increase in the depth of penetration, as well as in the concentration of impurities

Multilayer Coating Formation at the Deposition from Plasma

The numerical experiment was carried out for the process of the coating composition formation during deposition from plasma. The chemical reactions between elements are taken into account. The nonuniform composition of the coating is determined by various transfer processes, including diffusion under stress action. To find the stress field the equilibrium problem was solved numerically because all physical and mechanical properties depend on composition. Stress field has been also obtained nonuniform

Coating combustion synthesis controlled by moving electron beam

The model of the coating synthesis on the substrate is suggested at the conditions of electron beam controlling. The detailed reaction scheme in the treated layer is taken into account. Reaction kinetics is described based on mass action law. Reaction retardation by solid reaction products is taken into consideration. The review of similar models, simple and coupled, is made. Asymptotical solution of the particular coupled problem with summary reaction scheme is obtained. It was found that self sustaining mode is possible when the coating is synthesized on the substrate. The example of maximal temperature establishment is illustrated for the detailed reaction scheme in the Ti-C-Al system when the conversion is initiated by electron beam