agency of technological affectings on quality combined himiko-mechanical pokryti
5.5.1.vlijanie the temperature factor
The thermal effect manifested in the course of formation ViHMOP, renders an essential role on structure and quality of a covering.
Thermal processes at oksidirovanii aluminium are defined by character a formation chemical reaction gidroksida.
The basic quantity of warmth deposits in film pores, at their basis where there is a formation reaction gidroksida. Successful reception of coverings of the big thickness depends on that, how much intensively it is possible to take away warmth from a reaction zone.Measurement of temperature of actuating medium was defined through the equal
Periods at work of installation within five hours (fig. 5.15).
Fig. 5.15. Change of temperature of actuating medium on processing time at амплитуде:1
Interplane distances in And
- 1 mm; 2 - 2,5 mm; 3 - 4 mm
From 5.15 results resulted on fig. it is visible, that observable slight increase of temperature almost linearly. It is possible to explain an increase of temperature the thermal processes occurring at oksidirovanii, however constant circulation of a solution provides stability of a temperature regime. The greatest value of temperature - 308 To occurs at work with amplitude of 4 mm.
In the course of sedimentation of coverings (for example, zinc) at ViHMO there is a slight increase of temperature at the expense of the chemical
Component of process of an aquation of ions of zinc (Zn ~~ nH ~) and contact loading. Long researches of a temperature regime have shown, that the range of raise of an operating temperature does not exceed technological norms and does not render essential agency on operational parametres of a covering.
At an increase of temperature ionic mobility and molecules which positively influences speed of the chemical processes proceeding at machining increases, and can speed up speed of a build-up of a qualitative covering.
The factors operating ionic mobility, a Coulomb force co-operating between the proximal neighbours, and partly induction, depending on mutual polarisation of ions is. As conductance and chemical activity of process is connected with traffic of ions with an increase of temperature it will increase because of growth of a kinetic energy of the ions leading to easing of communications between heteronymic ions and facilitating their transmitting traffic.
Simultaneously with raise of growth rate of a covering speed of a dissociation of chloride of zinc being in a solution increases. Excess of ions of chlorine () will not only activate zapassivirovannye sections
Covered surface but also to loosen a formed covering, that in some cases meets operational demands to coverings.
On fig. 5.16 change of temperature of the actuating medium, defined is presented at regular intervals at work of installation within five hours at amplitude of oscillation Aa=2,5 mm and Aa = 4 mm.
Fig. 5.16. Change of temperature of actuating medium on processing time at amplitude:
1 - 2,5 mm; 2 - 4 mm
On fig.
5.16 it is visible, that in the course of work of installation the temperature of a working solution grows and attains the maximum values in two hours, then is stabilised. The higher temperature is observed at an amplitude of oscillation of 4 mm, but it, as a rule, is not applied, and in our work in detail was not observed. The increase of temperature at increase in an amplitude of oscillation of the working chamber occurs as a result of increase in speed of traffic and energy of collisions of corpuscles of actuating medium that leads to a reinforcement of reactionary processes as formations, and sull destruction.The analysis of the temperature researches spent at drawing oksidnyh of coverings, has shown, that in process vibrovolnovogo affectings formation of coverings proceeds at the stable temperature which is not exceeding a temperature regime, caused by GOST 9 for drawing of coverings. Stability of temperature is provided with circulating traffic of actuating medium at which it is intensively taken away warmly from a reaction zone in chamber total amount where there is a levelling of temperatures.
Thermal processes proceed in a reaction zone that leads to a solution increase of temperature in film pores, at their basis where there is a formation reaction gidrooksida aluminium. The increase in speed of dissolution of a covering will be a consequence of it.
5.5.2. Agency of speed of a leakage of a chemical reaction
In the combined process the condition of a blanket of a covering depends on speed of sedimentation of a put layer. According to fundamental law of chemical kinetics speed of the chemical reaction defining productivity of process, is proportional to product of concentration of reacting agents:
I where To - a constant of speed; Caи s - molar concentrations of reacting agents.
In process oksidirovanija one of reacting agents (aluminium) is in a firm condition. According to the law of chemical kinetics of concentration of the reacting agents which are in a firm condition, are not considered, as their concentration are constant also they react only to a surface which remains invariable.
Having marked out product of constants through To, we will gain
I
I.e. speed of reaction is proportional only to concentration of the substances which are in a solution.
According to the activation theory chemical interacting is entered only by the active molecules possessing energy, sufficient reaction for realisation. Having increased number of active molecules, it is possible to increase speed of reaction as it directly depends on an activation energy.
In process vibrovolnovogo affectings there is an activation not only a processed surface, but also molecules which, having gained additional energy, begin active the Excess energy can be in a molecule in various forms:
1) the raised kinetic energy forward or a rotary motion;
2) the raised energy of mutual oscillation of atoms or the atomic groups making a molecule;
3) the raised energy of traffic of bodies or others elektronov.
Energy elektronov in atoms can raise at valence bond rupture, activation can be carried out at chemical interactings, blows of molecules about a wall of a vessel, etc.
Thermal processes at oksidirovanii aluminium are defined by warmth of reaction of formation gidroksida.
According to Hess's law the thermal effect of reaction does not depend on a reaction way, and depends only on an initial and final condition of substances provided that process proceeds at constant volume or at constant pressure.
On the basis of Hess's law the power thermal effect of reaction of formation gidroksida is computed
Values of a standard enthalpy (LN) for the substances participating in reaction of formation gidroksida of aluminium, can be gained from works [99, 149].
Aluminium LN =0; water LN = - 68,317 kcal/GRAMME-MOLECULE; gidroksid aluminium AN-304,9 kcal/gramme-molecule; hydrogen LN = 0.
Values of thermal effects are referred to to temperature, equal 298,16 To.
In the equation for an enthalpy reaction
Substituting digital values find thermal effect (energy) of reactions
From this equation follows, that formation of 1 gramme-molecule gidroksida aluminium is accompanied by allocation of warmth of 94,95 kcal.
In the industry for heat removal at anodic oksidirovanii mixing or ammoniacal cooling of electrolytes is used. Intensive mixing of an electrolyte can sharply reduce temperature in a zone of reaction owing to martempering of conditions of heat removal and diffusion of a solution from pores oksidnogo a layer.
Thus, formation and growth of qualitative sull at ViHMO are possible under a condition:
1) simultaneous oxidation of aluminium in the heart of pores and chemical dissolution of a film;
2) activations of the molecules participating in process oksidirovanija;
3) circulation of an oxidising solution.
That the formation chemical reaction gidroksida aluminium proceeded with certain speed, the activation energy is necessary. Energy is necessary for clearing of an ion from gidratnoj shells, overcomings of a barrier of passivation and formation of a new phase.
The speed of the chemical reaction which has been referred to to unit of a surface, is equal where To - a constant of speed; With - activity of reacting agents in the solution layer, bearing against the surface metal; E - an activation energy, a kal/GRAMME-MOLECULE; R - a gas constant, kal/grad.mol; T - absolute temperature, To.
From the resulted equation it is visible, that only those ions which possess at present an activation energy not more low E, can react. Hence, the more active molecules, the above speed of reaction and possibility of reception of qualitative coverings of a demanded thickness. The number of active molecules can be increased, having informed inactive molecules additional energy, in this case in the form of vibrating himikoyomehanicheskogo affectings. An activation energy it is possible to count as follows: having marked out a constant of speed of oxidation of aluminium at temperatures t1 and t2 accordingly through Кіи К2, define its value as parabolas where R - a relative gain in weight of a covering, g/m2; t - processing time, ch.
E
Having substituted the gained magnitudes in the equation V = KSet, after taking the logarithm we will gain:
Value of an activation energy () is defined on a difference of logarithms of constants of oxidation:
Then
Or
~ G 2 1
Having solved the equation, we gain value E=279,6 a kal/GRAMME-MOLECULE. Value of constant C it is found from the equation
According to the activation theory a necessary condition for formation of new phases is mutual collision of molecules at which elektrony or atoms of one molecule get to sphere of act of the electric fields energised by corpuscles of other molecule. Knowing number of facing molecules Z and a share of active molecules - e, it is possible to define number of the molecules reacting in 1мл for 1 with.
The number of collisions is defined by a relationship
Where N - number of molecules in 1 ml; g - molecule radius; M - molecular weight.
From the resulted formulas it is visible, that the more effective collisions, the above speed of reaction and intensity of reception vysokoresursnyh ViHMP.
Under the influence of settlement oscillations working chambers (chapter 4) and medium of a molecule of reacting agents is energised, i.e. their intrinsic energy therefore the share of active molecules ~ and ions leads to qualitative increase in effective collisions increases. Feature of machining
Consists in that in the course of vibrating mixing of a solution concentration restrictions are eliminated, there are the intensive microstreams captureing diffuzionnyj a layer, that also influences speed of a current of process and quality gained ViHMP.
The carried out analysis shows, that vibrating machining provides formation and growth conditions oksidnyh coverings at the expense of the loading calling elastic-plastic deformation in a zone of contact, formation juvenilnyh surfaces, the active centres and circulation of the actuating medium providing an influx of a fresh solution in a reactionary zone, heat removal and consolidation of pores.
5.5.
More on topic agency of technological affectings on quality combined himiko-mechanical pokryti:
- 5.8. Power factors for maintenance of quality of the combined himiko-mechanical coverings
- the combined processes of machining at a combination of mechanical affecting to other aspects of affectings
- 1.4. Discussion of available sights on physical rules of mechanical chemistry of a solid with reference to process of the combined formation of himiko-mechanical coverings
- the Feasibility report on efficiency of application combined vibrating himiko-mechanical oksidnyhcoverings
- technological possibilities and prospects of use of a vibrating himiko-mechanical zinc covering
- 5.12. Corrosion durability combined vibrating vysokoresursnogo himiko-mechanical oksidnogo coverings
- Technical-economical analysis of results of use combined vysokoresursnyh himiko-mechanical coverings naosnove molybdenum disulphide
- influence of physicomechanical and himiko-technological properties of dry components of mixes on quality indicators of finished goods and criteria of an estimation of its quality
- recommendations about maintenance of quality and to application of vibrating production engineering for drawing of himiko-mechanical coverings
- CHAPTER 5. AGENCY OF TECHNOLOGICAL PARAMETERS OF THE COMBINED PROCESS ON OPERATIONAL PARAMETERS VYSOKORESURSNYH OF COVERINGS
- 3.11. Agency vibrovolnovogo affecting and a chemical component of process on formation pokryti
- IVANOV Vladimir Vitalevich. PROCESSES And METHODOLOGY of CREATION of BLANKETS VYSOKORESURSNYH of PRODUCTS BY VIBRATING FORMATION of COVERINGS by the COMBINED HIMIKO-MECHANICAL AFFECTING. The dissertation on competition of a scientific degree of a Dr.Sci.Tech. Rostov-on-Don 2017, 2017
- Technology of himiko-mechanical polishing of monocrystal germanium
- 5.7. An estimation of a resource and durability of vibrating himiko-mechanical coverings