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Diesel engine cylinder restoration by iron – carborundum composite galvanic coating in a centrifugal hydrodynamic field


Author: Dumitru Croitoru
Degree:doctor of engineering
Speciality: 05.20.03 - Exploitation and Maintenance of Agricultural Machinery and Food Industry
Year:2005
Scientific adviser: Ghenadie Gurianov
doctor habilitat, professor
Scientific consultant: Jana Bobanova
doctor
Institution:
Scientific council:

Status

The thesis was presented on the 20 October, 2005
Approved by NCAA on the 22 December, 2005

Abstract

Adobe PDF document – 0.47 Mb / in romanian

Keywords

cylinder, cylinder mirror, engine, Diesel engine, components restoration, repair, technological process, technology, electro-chemistry, electric precipitation, galvanic coatings, iron, chromium, anode, cathode, current strength, current density, tension, current efficiency, potential, polarization, electrolyte-suspension, dispersed phase, particle size, concentration, carborundum, iron compositions, composition galvanic coatings, anode rotation, hydrodynamics, centrifugal hydrodynamic field, mathematical planning of the experiments, regression equation, algorithm, programming, content of the composition coatings, desirability function, optimization, structure, sub-microstructure, dislocation density, microdistortion of the crystal lattice, mosaic blocks, icrohardness, wearing capacity, physical and mechanical properties, attrition, rider, machinability, burnishing, hone, honing, diamond hone, pressure, unit pressure, double-stroke number, empirical testing, field trials, practical concernment, application, economical result

Summary

In this thesis the investigations for development of a technologic process of the Diesel engine cylinder restoration by iron-carborundum composite galvanic coating (CGC) have been carried out .

A new method of CGC-application in a centrifugal hydrodynamic field (CHF) produced by the anode rotation in a stationary bath filled with electrolytic suspension (ES) has been developed. It has been ascertained that the electrolysis process with the intensive ES-concitation in the CGC influences on the electrode electrochemical activity, produces the depolarization effect and promotes formation of the qualitative coating on a cathode. It has been found that the particles of the dispersed phase (DF) and the precipitation conditions have a considerable effect on the characteristics of the thin structure defining physical and mechanical properties of coatings. The regularities of the iron-carborundum CGC formation in a centrifugal hydrodynamic field have been determined and their physical and mechanical properties have been studied. The change in the frequency of the anode rotation in the wide range provides possibility to control the CGCcompound. The best evenness of the coatings in CHF is achieved at the medium anode frequencies and the maximal concentration of the DF-particles in the electrolyte. The mathematical models of the relationship between the factors of the electric precipitation of coatings and the technical characteristics of the iron-carborundum CGC are obtained. The electrolysis process is optimized on the basis of the desirability-function for the compound and evenness of CGC.

It has been studied the influence of the concentration and the sizes of the solid dispersed particles of carborundum (SiC) on the CGC wearing capacity in the close-to-reality conditions. The optimal content of the DF-carborundum in the composition iron coatings, which provides the least linear attrition of the specimen with CGC and of the chromium-plated rider, has been found. It has been proved the possibility to hone the CGC-cylinders with coarse-grained diamond hones without prior burnishing. It has been established the relationship between the precision index and the factors of the mechanical processing, from which the hone pressure and the hone frequency rotation have the main effect. The technological process was applied in the Alexandreni engine factory.

This work has been done in accordance with the State Target (Plan) of the Academy of Science of the Republic of Moldova, issue “Investigation of the regularity of formation the wearproof iron coatings” (State registration Nr. 01860012790, 05.02.09.Тб), the Republican scientific and technological program 04 “Development of a progressive electrophysical technology”, the Republican interindustrial scientific and technological program 09 “Development and application the new technological processes of engine components restoration, which increases their wearproof by the factor of 1.5 … 2”.