The dissertation thesis devoted to solving an urgent scientific-research and practical-scientific problem, which consists in modeling and research of structure features formation of wear-resistant hardfacing coatings on the basis of Fe-Ti-B-C system with Mo addition, with the use of pure metals powders, and receiving the material on the basis of such system with increased durability in the conditions of long-term operation abrasive action.
The scientific literature analysis concerning the systems used as a basis for the electrodes intended for restoration and increasing of wear resistance of details of the equipment working in the conditions of the increased abrasive action is carried out. The modern market of electrodes of manufacturers of different countries offering electrodes for restoration of such equipment is considered. It has been found that most scientists and manufacturers direct research and development of wear-resistant materials based on Fe-Cr-C systems, which is characterized by high hardness, but such hardness is provided by the fragility of the structure, which consists of large chromium carbides and brittle eutectic. Additives of boron and metals Mo, Ti, V, W, Nb, Ta are mainly aimed at forming a more equilibrium structure and improving the physical and mechanical properties of structural components, while the processes of structure formation remain unchanged, which leaves the question of finding an alternative system bases for the manufacture of wear-resistant materials.
Prospects of research of Fe-Ti-B-C system, and its application as a basis for development of wear-resistant material with high indicators of physical and mechanical properties and stability in the conditions of the increased loading are considered. It was also found that the use of this system is appropriate only when using Ti as a pure metal powder, in contrast to its common (and other carbide-forming and boride-forming metals of group IV-VI of the periodic table of chemical elements) by scientists and manufacturers of electrodes in the form of ferro powders. The use of pure metal powders in the reaction mixture Me + B4C provides the implementation of the so-called in-situ technology during the production of the coating, which is a fundamentally different mechanism of structure formation than remelting during the use of ferro powders. It is established that the physical-mechanical and operational properties of such materials are higher than those obtained from ferropowders.
A comparative analysis of methods of obtaining a wear-resistant coating, from the standpoint of simplicity of the method, economic feasibility, productivity, purity / quality of the obtained coating. Among the considered common and some special methods of obtaining a wear-resistant coating, as the most versatile, productive, feasible from the point of view of research and providing high quality coating, chosen electric arc surfacing with powder electrodes, also known as FCAW (Flux-Cored Arc Welding).
Experimental electrodes with a reaction mixture of Me + B4C were developed, where Me is a mixture of pure metal powders (Ti + Mo) 30%, at., At concentrations of molybdenum (in a mixture of Ti + Mo): 0 %, 10 %, 20 %, 30 %, 40 %, 50 %, 60 %, 70 %, 80 %, 90 %, 100 %, at. The study of the microstructure and phase composition of materials by scanning electron microscopy (SEM) and X-ray phase analysis, study of physical and mechanical properties, technological parameters, laboratory studies of materials under different conditions of abrasive and shock-abrasive action.
Thermodynamic modeling of materials of the Fe-Ti-Mo-B-C system is performed and the thermodynamic database of this system is developed.
On the basis of the modeled data and their interpretation with experimental data, definition of physical and mechanical properties, results of the carried-out experiments the research material with the highest complex indicators is defined. Based on this system, a batch of electrodes was developed to restore and increase the wear resistance of equipment operating in conditions of mixed abrasive action in order to test the test material in real operating conditions.
Industrial testing of the developed electrodes was carried out and confirmed the results of laboratory tests and technical and economic feasibility of using the developed powder electrodes based on Fe-Ti-B-C system with the addition of Mo for restoring and increasing of wear resistance of parts in the working conditions of intense abrasive wear and high specific and cyclic loads.
It is established that the wear resistance of the working surfaces of knives for removing bark from wood and sections of press augers for the production of building ceramics deposited with developed electrodes increases the durability by 2,8 and 1,9-2,0 times, compared with parts restored with serial electrodes.
