Physico - chemical properties of multicomponent inhibitors of metals corrosion and anticorrosion covers

Actuality and claiming of of dissertation theme. In present time in different ranges of economics of countries with intensive development industry prevention of corrosion of metals and elaboration of inhibitors and anticorrosion covers is one of actual and important task. In countries of the world with development chemical and oil-chcmical industry losses from corrosion of metals is equaled 30% from their year production; corrcspondcntly construction and using of inhibitors of corrosion and anticorrosion covers in practices has a very important value.
During of years of independence of Uzbekistan have been introduced programs by introduction of modern technologies in industry. For protection of equipment corrosion inhibitors and anticorrosion covers arc used, with this aim in our country a systematical scientifically investigation by elaboration of new types of inhibitors and anticorrosion covers have been carried out.
In industrial scales influence of inhibitors and anticorrosion covers of polymeric type on corrosion of steel have been investigated with aim of their introduction in practices. Inhibitorial protection of technological equipment and pipelines working in aggressive mediums, increasing of their stability and durability is one of the effective problems.
Inhibitors of corrosion arc used for obtain stable covers and chemical compositions connecting oxygen or some ions; as additions in compositions; curvers in circulating water systems; in oil-chemical and oil-refining industries, any energetically mountings; for protection of microelectronics and modem army technics; they arc added in fuel, building materials. In last time water-soluble high molecular compounds also are used as inhibitors; often they are used for fight with salt- and slamo-dcposits but also they can be used as potential inhibitors of corrosion owing to their low toxicity.
Modem classification of inhibitors has included oxidizers, inhibitors of adsorbsional type complex formating and polymeric types. Such devision has witnessed about variety mechanisms of their action and possibilities of using of achievements of different fields of chemistry for protection of metals from corrosion. The special significance is dewoted to corrosion inhibitors using in water mediums.
In number cases the high role is devoted to anticorrosion covers. Knowledge of theoretical states of corrosion and mechanisms of protection from it has allowed to elaborate of anticorrosion covers with properties of modeled rust. At this great role is devoted to displaccmcat of deficit components by local raw materials -many-tonal waste of oil-fating and chemical industries such as gossipolic resin, cotton soapstock, hydrolyzed lignin.
This dissertation work is oriented on the realization of resolutions of President of Republic Uzbekistan PP-916 from 15 June 2008 year “About additional measures by stimulation of introduction innovational projects and technologies in production” and PP-1071 from 11 March 2009 year “About program of measures by acceleration of constructions and mastering of production of new types of chemical production”.
Aim of investigation. Elaboration of new class of multicomponent inhibitors and anticorrosion covers for effective protection of metals from corrosion and investigation of their physico-chemical properties.
Scientific novelty of dissertational research consists in the following: determination of protection mechanism elaborated multicomponent inhibitors and anticorrosion covers of new generation and also possibility of formation of self-organizating surface layers;
it was determined that particulitiers of multicomponent inhibitors having a high adsorption on mctalic surface have carried out to marked decreasing of navozajing of steels;
degree of fulfilment of electrod surface, rate of solution of metal, the constant of adsorption equilibrium and coefficient of interaction of components of mixed inhibitors have been determined;
it was determine that phenoment of sinergism has been noted in the presence of high molecular compounds especially strong it has been noted in comparison with low-molccular aliphatical amines what can be explain by differences in mechanisms of action of inhibitors of different chemical nature;
it was proved that treatment of rust surface by covers on the base of gossipolic resin has promoted to modification of corrosion products in hard-soluble stable compounds decreasing of process of metals destruction.
CONCLUSION
1. On the base of systematical fundamental investigation of kinetics of clcctro-chcmical processes and mechanism of inhibition for the first time a number of particulities of inhibitors of different chemical nature have been determined what has allowed to elaborate of scientifically-based approach to elaboration of effective, ecologically safe, economically advisable, import-substituted inhibitors of corrosion of polymeric type on the base of local row-materials; waste and byproducts of chemical, electrochemical and mining-metallurgical industries.
2. It was shown that mechanism of anticorrosion protection by two-componcnts inhibitors of polymeric type containing polyphosphates principally has differed from action of low-molccular inhibitors. Inhibitors on the base of high-molecular compounds have formed complexes with low-molccular components containing in composition of corrosion deposits caused to their condensation and making their low perspicacious for corrosion-active reagents; than adsorption processes have carried out couse to decreasing of growing of phosphate layer owing to which it became less prone, more thin and it’s protection properties have been increased. Amine-containing two-component inhibitors have displaced donor-acceptoral interactions owing to presence of individed electron pair of nitrogen atom of amino-group with atoms of metals but difference in protection action of amines (RNFb) in the presence of polyphosphates can be caused by different degree of fulfillment of steel surface what from positions of local interactions is connected with peculiarities of microrclief of adsorbent surface and value the constant of distribution of adsorbate between of contacting phases.
3. For the first time it was determined that synergism especially strong is noted in the presence of high-molecular compounds (NaPOaVunifloc, Na-jPiO?-unifloc, КадРгОт-Ка-СМС, Na-^Ch-gclatin, Са^РгОу- gelatin in neutral and weak alkaline mediums (pH=7+9) in temperature interval 20+40 °C; also it is necessary to note that synergism at using of different alyphatical amines is less expressed what can be explain by differences in mechanisms of action of inhibitors of different chemical nature. It was shown that inhibitors of polymeric type are effective in neutral, weak acid and weak alkaline mediums while low-molecular inhibitors have caused high inhibition properties only in neutral and weak-acid mediums.
4. By comparison physico-chemical investigations of mechanism of inhibition of corrosion process by inhibitors containing high-molecular components in comparison with low-molccular inhibitors regularity has been determined that in spite of essential differences in mechanisms of their action the coefficient of mutual influence of components, degree of fulfillment of electrode surface and the constant of adsorption equilibrium have the highest values at equimolar ratios of components of inhibitors exceeding in 4 times others ratios in case of inhibitors of polymeric type and in 2 times in case of low molecular inhibitors.
5. It was shown that inhibitors containing polyelectrolytes (which arc surface -active component) have fulfilled role of regulator of rate of electro-precipitating of phosphate-ions on the surface of steel that is to prevent excessive growth of layer of phosphates and to provide it’s uniformity. Than adsorption process has carried out by Lcngmuir with formation of monomolecular nanolayer. In case of low molecular inhibitors different mechanism is realized which is bonded with
constant of distribution of amino compounds between solid and liquied phases on the border of their division.
6. Thermo-dynamical calculations of the effective energy of activation of metals corrosion AGeff, for polymeric and low-molccular inhibitors have shown that high negative values of this parameter have indicated on affcctivity of mixed inhibitors containing in their composition high molecular compounds. Investigations of concentration dependence of AGeff have allowed to determine optimal concentration range of inhibitors.
7. By electrochemical and elcctro-microscopical investigations it was determined that adsorption of aliphatical amines on the surface of steel from liquid phase has carried out considerably slower and is characterized by more reversibility in comparison with adsorption on the ferrum phosphate.
8. Technologies drawing of obtained of anticorrosion covers on the base of GR on procorrosiating surface have been elaborated. It was shown that covers on the base of GR can be used as modificators of rust and priming material for friable rust surfaces: they were tested on industrial objects and also they were introduced in practice of laboratories of AS “Almalik GMC”. For increasing of protection properties of modified layer of rust or for decoration works it is possible to draw lacquer painted surfaces on the any base on the treated surfaces of metals.
9. Physico-chemical parameters of process of electro-chemical corrosion of steel in presence of elaborated inhibitors in dependence on their composition, concentration, pH of medium, temperature were determined. Also optimal conditions providing a maximal protection have been determined. Comparison of inhibitoral ability of elaborated inhibitors has shown that at pH=5-r9 and temperature interval 204-80 °C two-component inhibitors (NaPOj)n-unifloc and Na4P2C>7-gelatin have the best protection properties. Application of elaborated inhibitors of corrosion has decreased chemical and electro-chemical constituting’s of metals corrosion in technological mediums. Effectivity of inhibition has been equaled to 97,63 % at temperature 50 °C owing to formation of continuous passiving films on the surface of metals. At this rate of corrosion of equipment has decreased to normative values. It was shown that protective effect of elaborated inhibitors on the base of waste production and local materials has exceeded to 5% in comparison with importing expensive inhibitors. Elaborated inhibitors were tested and introduced in practics of AO “Navoiazot”.