A thesis for a degree of candidate of technical science (Ph.D.), speciality 05.03.07 –Processes of physical and technical treatment.- National technical university of Ukraine “Kiev Polytechnic Institute name of Igor Sicorskiy”, Kyiv, 2021.
Dissertation is sanctified to forming of the modified layers from submicro- and by a nanocrystalline structure and increase level of operating properties at superficial treatment of thread instrument from high speed steel and carboloies by a plasma stream. In a literary review the executed analysis of terms of work of thread instrument. The character of wear of thread instrument, mechanisms of wear, zone of wear. the shown perspective of development of different methods of strengthening is for the increase of capacity of thread instrument. The feature of thread instrument it a very large nomenclature as on sizes, from ultrafine markers, to the large milling cutters, chisels, so on the variety of kinds. Presently there are 4 approaches to strengthening. Most develop lately this causing of coverages, and superficial retrofitting. These two most widespread метода just develop toward the receipt of dispersible structures including nanostructures.
Dissertation work is executed on a plasma complex in the conditions of department "Nanoengineering in a branch engineer", the basic element of this complex it a plasmatron. A plasmatron is used indirect action: a detail and instrument are electric neutral. Feature of his construction this partitioned interelectrode insertion. Specially in an order to promote cooling speed and get plasma nanostructure. It is set experiments, that it is possible to influence on this process by implementation of channel of plasmatron not cylindrical form, but conical. Measure of narrowing of channel influences on hardness at treatment. Worked out methodology of mathematical design of process of the plasma retrofitting of thread instrument. In basis of calculation of thermal action of concentrate sources of heating the law of heat-conducting of Fourier lies on a metal. For the decision of this task an usually-element design is used with application of the applied package of МСS.Nastran.
A mathematical optimal case of the plasma superficial retrofitting of thread instrument a process frame and engineering methodology of calculation of the optimal modes of treatment are worked out. First on the basis of usually-element decision of differential equalization of heat-conducting in the nonlinear raising the worked out algorithms and engineering methodologies of calculation of the optimal modes of the plasma retrofitting of thread instrument from high speed steel and carboloies that provide formation in the modified zone of submicro- and nanocrystalline structure with an increase level of operating properties. In the third part of dissertation an investigational structure and properties of thread instrument are from high-speed steel on the example of comb. For such instrument two approaches are known by plasma retrofitting with by volume heat treatment and with triple vacation Type of structure that appears in the modified zone as a result of the complex by volume of-superficial strengthening of combs from steel of Р6М5 occupies intermediate position between nanocrystalline (to 100 nm) and microcrystalline.
The mechanisms of structural transformations of comb are investigational from high-speed steel and thread chisel from a hard-alloy plate at the plasma superficial retrofitting. The set conformities to law of nanostructure of cutting edges of thread instrument are at the plasma retrofitting without melting surface. It is set that during nanostructure of steel instrument of acquisition of the most high values of dispersion is conditioned by the increase of cooling speed, dissolution of initial carbides and selection of nanodispersible secondary carbides.
Methodology of tests is worked out and investigational crackfirmness, mechanisms of destruction and wear of thread instrument with the superficial modified layer. A technological equipment is worked out for realization of plasma treatment. The technological processes of the plasma retrofitting of thread instrument are worked out from carboloies and high speed steel. The worked out flow diagram of management of nanostructure is after the plasma retrofitting. Worked out recommendations on the choice of the optimal placing of the modified zone on a thread chisel by hard-alloy plates and thread combs from high-speed steel. Firmness studies of thread instrument are undertaken after the plasma retrofitting.
Key words: plasma modification, threading tool, fracture mechanism, crack resistance, wear resistance, mathematical model, structural transformations, surface layer, microstructuring, nanostructuring, meso-structures, ultra-disperse.
