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  • Increase of technological reliability of preparation of details of mobile equipment for galvanic sedimentation of zinc coverings

    Zinc electrodeposits gained the distribution generally thanks to high protective properties. However it is possible to apply zinc electroplated coatings and at restoration of worn-out surfaces of details of cars. Thus zinc electrodeposits possess the high durability of coupling with a substrate that is pledge of long-term service of the details restored by zinc. Ensuring high durability of coupling of zinc electroplated coating with a basis possibly only at careful observance of technological process of preliminary preparation of a surface for sedimentation and directly the sedimentation. Some researchers suggest to estimate the received durability of coupling of a covering with a basis from the point of view of the theory of reliability. Technological reliability of process of preparation of details for galvanizing is meant as percent of the restored details, with a high durability of coupling. Process of preparation represents technical system in which operations act as elements. Reliability of technical system are defined by quantity and reliability of elements, their functional communication. And reliability of elements, is defined by technology factors and depends on quality of carrying out the previous operation. Refusal of any of elements causes refusal of all technical system. That is communication between elements of system consecutive and it is possible to apply the second theorem of probabilities according to which the probability of joint emergence of several dependent events is equal to work of probability of one of them on conditional probabilities of all others to it. It is necessary to understand change of reliability of an element in time as stability of reliability. For the purpose of improvement of technological process of galvanizing it is possible to perform operation of anode etching directly in galvanizing electrolyte. Thus the block diagram of preparation of a detail can be submitted as follows: machining; degreasing of surfaces of a detail Vienna lime; washing in cold water; anode etching galvanizing electrolyte; removal of products of etching from the covered surfaces and an exit to the mode; galvanizing.

    Keywords: case detail, restoration, repair, defect, resource way of restoration, car repair production

  • Choice, control, and correction of electrolyte galvanizing restoring of surfaces of details of cars

    The choice of the electrolyte for the galvanic deposition of coatings is one of the fundamental points to ensure high quality and reliability of the reconstruction of surfaces of machine parts. Zinc electroplated coatings currently used in the automotive and car repair production mainly as protective coatings. However, in addition to the protective properties of zinc galvanic coating has sufficient hardness and wear resistance, and damping characteristics. From the composition and type of the electrolyte depends on the quality of sediment, its continuity, physical and mechanical properties, adhesion to the substrate, and the performance of the deposition process, the service life of the electrolyte, and the frequency of service (filtering, correction, and so on), the mechanism of occurrence of electrolysis, types and rate of the electrochemical processes. When the metal plating of zinc are used mainly the following types of electrolytes: slightly acidic; acidic, coroborate, chloride, soleplate; alkaline, and mixed electrolytes. In use, in practice, the greatest use of acid, weakly acidic and alkaline. The optimal choice of the electrolyte galvanizing ambiguous, as the process of electrolysis depends on many factors and is characterized by more than twenty different indicators. The analysis showed that the main selection criteria are: quality of galvanic sludge - corrosion resistance, adhesion to the substrate, the distribution of sediment thickness, aromatherapist, flexibility, adaptability to soldering and decorative properties; technological parameters of deposition - the range of the cathodic and anodic current density, the productivity of the deposition, the temperature of the electrolyte, the velocity of the electrolyte, etc.; safety for humans and the environment; saving resources and costs; the stability of the electrolyte and ease of maintenance.

    Keywords: passive film, adsorption, sedimentation productivity, electrocrystallization, mechanical activation, crystal lattice

  • Theoretical justification of possibility of anode etching of the restored details of cars in sulfate electrolyte of galvanizing

    Carrying out anode etching of details directly in working electrolyte of galvanizing will allow to reduce significantly time for preliminary preparation of the restored surface for sedimentation and to increase stability of results on ensuring quality of a covering. Anode etching represents electrochemical processing during which there is a removal of oxidic films, dissolution defective superficial a metal layer, revealing its structure. Thus on an anode surface the slime consisting of etching products is formed and ions of bivalent iron get to electrolyte. At achievement of a certain (critical) value of density of anode current the process of passivating of a surface, that is a surface covering a passive film which is followed by sharp increase of tension and decrease in current begins. There is a rough allocation of the small vials of oxygen clearing slime from an anode surface. The mechanism of anode etching of surfaces of the restored details of cars in sulfate electrolyte of galvanizing is similar to etching in the electrolytes containing sulfate ions that is as a result of process of formation of an oxidic film and parallel electrochemical dissolution by its anions. Quality of electroplated coatings of the restored details of cars zinc is provided with anode etching on necessary depth before emergence of steady passivation and the subsequent covering of a surface a continuous passive film. The mechanism of passivation of a surface of the anode in the electrolytes containing sulfate ions can be described by two theoretical models: 1) passivation is caused by protection of a surface an oxide layer of metal; 2) passivation is caused by special nature of adsorption of ions of oxygen. At achievement of anode density of current of a certain (critical) value, and change of active dissolution of a surface by the steady passivation which is followed by formation of a monomolecular passive film happens an electrode of a certain value of potential.

    Keywords: anode etching, passive film, current density, adsorption, passivating, potential

  • The method for electrochemical studies on the behavior of gray cast iron in sulfuric acid electrolyte during recovery of machine parts electroplating galvanizing

    The implementation of electrochemical research is needed to identify the nature and magnitude of the impact of the main technological factors on the processes taking place during anodic etching of grey cast iron in the electrolyte on the basis of sulphate of zinc. The main technological factors that affect electrochemical processes occurring, is the temperature and acidity of the electrolyte, the concentration of the basic salt of zinc in the electrolyte and other components, the speed of flow of the electrolyte in the cathode space, the cathodic and anodic current density, rotation speed of the electrode, modes of mechanical activation. Electrochemical studies were carried out in three modes: potentiometric, potentiostatic and galvanostatic. Resulting in the obtained polarization curves for all three modes. To identify the degree of influence on the growth of the limiting cathode current density of mechanical activation of the cathode surface was carried out electrochemical studies, which were obtained cathode potentiometric curves. These studies took place with anode under similar research conditions in the same laboratory setting. The main difference cathodic electrochemical studies was that mechanical activation of the rotating electrode was carried out by introducing into the electrochemical cell of the lever, with a fixed abrasive material, pressing it against the surface of the test electrode. Thus, this electrode has already played the role of the cathode. Conducting electrochemical studies of the behavior of iron in sulfuric acid electrolyte galvanizing by etching, mechanical activation of the cathode surface and deposition of the electroplated layer, allowed us to obtain sufficient experimental data to identify rational modes of electrolysis at all stages.

    Keywords: technological factor, electrochemical studies, polarization curves, electrochemical cell, electrode potentiostat

  • Theoretical justification of increase of productivity of galvanic sedimentation of coverings on the restored surfaces of details of cars

    Increase of productivity of processes of sedimentation of coverings on the restored surfaces of details of cars without decline in quality of the received deposit is a main objective on the way of improvement of galvanic processes. Productivity of galvanic sedimentation depends on the size of potential of the cathode and the anode; from concentration of components of electrolyte about a surface of sedimentation (cathode); from uniformity of delivery and dispersal of ions of metal on a sedimentation surface; from quantity of active sites of the cathode; from nature of passivation of the cathode; from temperature of electrolyte and from the speed of the movement of electrolyte in prikatodny space. Very strongly passivating of a cathodic surface limits the possible growth of productivity of galvanic sedimentation. Passivating consists in education on a surface of the cathode of the continuous passive film consisting of hydrogen, products of reaction of metal with electrolyte components, oxygen of air and foreign inclusions. The passive film is almost insoluble and disturbs electrocrystallization process, shielding a cathodic surface. And cathode covering speed a passive film directly depends on density of cathodic current. It is possible to assume that at achievement of some value of density of cathodic current the speed of formation of a passive film will exceed, the speed of delivery of ions of metal to a cathodic surface and origin of crystals of the besieged metal will become impossible. And on the remained active sites of the cathode where the passive film is absent or has the smallest thickness and growth rate, there will be centers of growth of crystals of metal (dendrites) on which there will be a concentration of the main processes of electrocrystallization. That is the cathodic surface of the restored detail will become covered by the local centers of sedimentation of metal – dendrites. The passive film interferes with growth of limit density of cathodic current at which receiving qualitative electroplated coating is possible. Mechanical elimination of a passive film during sedimentation of a covering considerably facilitates process of electrocrystallization and formation of a layer of metal on the processed detail surface, provides increase of uniformity of the received layer of metal and its microhardness, and also will prevent active formation of local sites of growth of dendrites at the high density of current.

    Keywords: passive film, adsorption, sedimentation productivity, electrocrystallization, mechanical activation, crystal lattice

  • The device for restoration of internal cylindrical surfaces of details of mobile equipment galvanomekhanichesky sedimentation of coverings

    Carry to the main advantages of galvanic ways of restoration: possibility of formation of a layer from several micrometers thick to 1-2 mm. metal or a combination of metals with the set properties, restoration "in the size", that is without the subsequent machining, simultaneous restoration of several surfaces and use of a small amount of electrolyte. A number of the devices allowing to provide the demanded conditions is developed for implementation of galvanomekhanichesky sedimentation of coverings. As the activating elements in these devices generally apply abrasive materials which working surface, in the course of work, "is salted", that is it is hammered with cutting products. It considerably reduces efficiency of activation of the cathode and uniformity of the received deposit in view of introduction in the formed layer the activating elements of products of activation. The offered device developed by Zakharov Yu.A. and Spitsyn I.A. it is deprived of such shortcoming in view of application of the activating elements in the form of leaders and the conducted abrasive rollers connected by a belt drive. For elimination of this lack of the existing devices by Zakharov Yu.A. and Spitsyn I.A. (patent No. 2503753) the device was developed for galvanomekhanichesky sedimentation of coverings on internal cylindrical surfaces of details. Difference of the offered device is that at sedimentation of an electrodeposit, the conducting and conducted rollers, being rolled on the activated cathode surface, rotate with various district speed because of their various diameter. As pulleys of leaders and the conducted rollers are connected by a belt drive, to the transfer relation no more than 0,8-0,9, on shaft of rollers there is various district force forcing the conducted rollers to slip rather cathodic surface. It provides better removal of the passivating film and continuous change of the surface of the activating roller contacting to the activated cathodic surface. Thus, the free surface of the activating roller is washed by a channel of electrolyte, being cleared of activation products that interferes with formation of so-called "zasalivaniye" of a wor1king surface of the activating elements (rollers).

    Keywords: case detail, restoration, repair, defect, resource way of restoration, car repair production

  • Experimental installation for laboratory researches of galvanomekhanichesky sedimentation of zinc from flowing electrolyte on the restored surfaces of details of mobile equipment

    Improvement of technological process of galvanizing in flowing electrolyte without decrease in its reliability and quality of the received deposit can be carried out by carrying out anode etching of the processed surface directly in the main electrolyte of sedimentation. And, providing such conditions of anode etching at which, the details which are formed on a surface products of reactions easily are removed a channel of electrolyte is possible. For the purpose of identification of extent of influence of technology factors on anode dissolution of the processed surface it is necessary to conduct elektrokhikmichesky researches. The installation including electric was for this purpose developed and made and gidravklichesky speak rapidly. The Elektkrichesky part contains power-supply circuits of an electrolytic cell to the asymmetric variables odnopoluperiodno straightened, dvukhkpoluperiodno straightened by current and straightened by current with the lowered pulsation, and also a chain of heating of working electrolyte. The hydraulic scheme of experimental installation includes: the kisloktostoyky electric pump, pipelines, filters, the device for an electrolytic precipitation of coverings and a bathtub with electrolyte. Electrolyte in a cell moved by means of the electric pump. Giving changed in steps, due to change of diameter of the section through passage of the giving pipeline by means of replaceable inserts. Authors of the device for electrolytic drawing coverings are Zakharov Yu.A. and Spitsyn I.A. (patent No. 2155827). The design allows: to increase the speed of a channel of electrolyte; to carry out activation of the cathode, using energy of a channel of electrolyte; to increase the accuracy of copying of the cathode the activating elements; to use higher density of current and to reduce power consumption of the device. Electrolyte, in the course of sedimentation, was constantly filtered. As filtering material used fiber glass. The filter if necessary it is possible to dismantle and wash out quickly. Such filtering element slightly interferes with a channel of electrolyte, is simple in service, is cheap and quite sufficient. Thus, the offered design of experimental installation allows to conduct necessary researches of process of sedimentation of a zinc electrodeposit for its improvement.

    Keywords: case detail, restoration, repair, defect, resource way of restoration, car repair production

  • The main defects of case details of cars and ways of their elimination applied in car repair production

    Production of case details – the difficult technological process demanding providing with the expensive specialized equipment, high-precision gages and defining a product level of quality. In this regard, the nomenclature of new qualitative case details in the market is very limited. In designs of cars case details are present practically at any knot or the unit. For example, the case of a transmission, transfer case (at its existence) the block of DVS cylinders, cases of the main thing and wheel reducers, cases of hydraulic and pneumatic pumps, cases of distributing devices, brake cylinders and so on. In article the concept of a case detail is considered, influence of quality of production and technical condition of case details on providing a resource of cars is revealed. Main types of influences which influence case details in use of cars are listed. Classification of the main defects of case details of cars is given, and the most perspective ways of their elimination in car repair production are considered. The listed ways found rather broad application in car repair production, but with growth of scientifically technical progress, emergence of new materials and technologies need improvement and modernization. Improvement has to be directed on increase of ecological safety, material and resource economy, reliability of technological processes and quality of the received result.

    Keywords: case detail, restoration, repair, defect, resource way of restoration, car repair production

  • The device for galvanomekhanichesky sedimentation of coverings on internal cylindrical surfaces of details of cars

    Sedimentation of electrodeposits with activation of a cathodic surface is in the flowing and contact way the most perspective way of restoration of internal cylindrical surfaces of details of cars. The existing devices for realization of this way have the merits and demerits, and can be therefore modernized and improved. On the basis of the analysis of the existing devices for galvanomekhanichesky sedimentation of coverings the new design is offered, novelty and which advantages is confirmed with the patent Russian Federation for the invention. The device contains the top and lower flanges in which there are branch pipes for a supply and removal of electrolyte. Between flanges the processed detail with rubber laying is established. The received tight electrolytic cell is pulled together with vertical couplers between a bed and a clamping plate. In the lower flange on a vertical axis the activating head consisting of the krylchatka bearing on herself three levers with is established by the activating elements which are movably fixed on them. Axial movement of a krylchatka is limited to the removable motionless anode. Pressing of the activating elements to the processed surface is provided at the expense of the elastic shock-absorbers located in rectangular grooves of a krylchatka and influencing the lower shoulder of levers. Tokopodvod to a detail is carried out by means of the contact device fixed on a bed, and to the anode via the contact plug from a source of a direct current. Circulation of electrolyte is provided with the acidproof hydraulic pump. The offered design is simple in production and doesn't demand existence of the expensive specialized equipment. The operating procedure with the device and sequence of operations doesn't contradict technology of sedimentation of electrodeposits. In article the main advantages of the device in relation to existing in car repair production are opened and proved.

    Keywords: case detail, restoration, repair, defect, resource way of restoration, car repair production