Production Processes and Properties of Powders
Copper cementation in dispersed form from sulphate solutions has been carried out by metallographic, polarization, weight, and volumetric methods. The mass balance of the cementation process is determined. The effect of chloride ions on the copper deposit shape is shown. Polarization measure- ments of the electrode processes of the aluminum-copper couple are performed. The full two-factor experiment has been carried out, which results in regression equations showing average particle size, bulk density, and deposition rate of copper powder depending on the cementation reaction conditions.
Structure formation of powder austenite produced with different compaction schematic diagrams is considered. It is found the steady fragmented austenite structure to be formed during compression in a closed die and transversal compaction. High degree and rate of deformation are shown to be ensured during hot forming according to the extrusion and non-equiaxial all-around compression resulting in preferential development of dy- namic and static recrystallization. In increasing the deformation degree according to the free compaction schematic diagram, the recrystallized grain sizes are reduced.
A model of cooling and crystallization of a melt drop produced by gas atomization is presented. The effect of process parameters of this method on the macro- and microstructure has been estimated. The particle diameter dependence of dendrite inter-axial gaps is established. Comparison of the microstructure of experimentally studied particles with the calculated data shows the good fidelity.
Theory and Processes of Formation and Sintering of Powder Materials
Taken sintered SPN14A7M5 steel as an example and using the mathematic simulation, the effect of porosity on the heat distribution in material during laser processing has been found. The calculated results have been verified by the experimental data. The effect of laser processing on the microstructure and properties of sintered SPN14A7M5 steel has been studied and the optimum conditions of the process have been found.
The effect of various modes of filler grain hard alloy metal sintering on its structure has been investigated. The strong dependence of structural ho- mogeneity of sintered alloy on carbon balance is shown. The processing methods for production of homogeneous structure of filler grain hard alloy metal are found.
Self-Propagating High-Temperature Synthesis (SHS)
The phase composition, structure and properties of SHS-compacted materials of the Ti-C-Al-Si system have been investigated. It is shown that metal- like titanium compounds can be used as cathodes of vacuum-arc evaporators. The coatings obtained from SHS-cathodes are of single-phase and re- present cubic titanium nitride of the (Ti, Al, Si) N composition. Their microdrop phase volume is 2,5-3,0 times lesser compared with TiN, and their micro- structure is not fragmented into low-strength columnar elements; the body-centered cubic lattice size is two times lesser than that of titanium nitride. Approximately given equal hardness and at the cost of lower elastic modulus, (Ti, Al, Si) N coatings essentially exceed TiN coatings in durability to elas- tic failure strain and plastic resistance. When milling tungsten-copper alloy, the lifetime of (Ti, Al, Si)N coated carbide cutters is 2,4 times more than that of cutters with TiN coating produced from titanium cathode with magnetic separation of plasma flow.
Refractory, Ceramic, and Composite Materials
Wear-resistance and microhardness of Feх(Al2O3)100–х thin-film nanocomposite coatings have been investigated in a wide range of metal phase con- centrations (30 ≤ х аt. % ≤ 95). The maximum hardness (up to 12 GPa) is observed in the composites with metal phase concentration of 80÷82 at.%. Wear resistance of nanogranulated composite measured at 2N load is shown to exceed that of 12Kh18N10T steel used as a substrate. Wear factor of Feх(Al2O3)100–х nanocomposite is 3,5 ∙ 10–5÷11,63 ∙ 10–5 mm3/(N ∙ m) at 2N load.
The results of investigation of porous composite ceramics produced from the Ti-B-C system by self-propagating high-temperature synthesis are given. The effect of titanium amount in the mix material and strength characteristics of synthesized porous materials have been studied. The re- sults of their investigations with the Jeol JSM-6390A scanning electron microscope, ARL X' TRA diffractometer and of INSTRON 5988 multiple-pur- pose testing machine are given.
Modification of Surface Including Charged Particle Beams and Photon and Plasma Fluxes
The dependences of metal surface erosion factors on the parameters of powerful impulse charged particle beams has been investigated with the use of mathematical simulation of dissipation processes of their energy in solid body. The energy balance over the target surface for beams with initial particle energy from 10 to 1000 keV and power density up to 1010 W/cm2 has been plotted. Power efficiency of atom removal away from the metal surface has been studied depending on the type particles, their initial energy, power density, and current impulse duration.
Nanostructured Materials and Functional Coatings
Studies of structure and properties of TiN-Cu coatings with a wide interval of copper concentrations from 0,6 to 20 at. % have been carried out in- cluding its cutting action tests. The coatings were produced by the ion-plasma vacuum-arc deposition onto TT10K8B carbide cutting tool. Introduc- tion of copper into the composition of the coating results in nitride phase crystallite size reduction from 100 to 20 nm. In this case the hardness of coatings grows from 20 to 40 GPA while copper content in the coating increases up to 7–8 at. %. Further increase of copper content, which is accom- panied by nitride phase crystallite size reduction, is characterized by decrease of hardness down to 14–15 GPA concerned with the effect of soft duc- tile metal on it. The life tests of mechanical cutting by TiN-Cu coated 35KhGSA SMP steel show that the optimum composition of the coatings (TiN – 7–8 ат. % Cu) increases the durability of tools with replaceable polygonal inserts (SMP) more than 6 and 2,5 times compared with uncoated tool and TiN coated tool according to the basic technique respectively.
The current state of functional surface and coating studies by glow discharge optical emission spectrometry (GDOES) has been analyzed. The main principles are described. For the purpose of determination of the requirements to samples and detection of potential possibilities of the technique, the GDOES-investigations of different composition coatings and structural characteristics, which are obtained by some procedures, have been carried out.
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