International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The phase and structure formation of aluminum-matrix composite materials reinforced with titanium carbide during their synthesis and consolidation using the forging were investigated. The influence of copper additives on the structure formation, density, porosity, and hardness of aluminum-matrix composites was determined. The research results revealed the presence of Al+Cu+TiC phases in copperalloyed samples. Studies of density and porosity showed that the samples without copper additives were maximally densified after hot stamping and had minimal porosity, unlike the copper-alloyed composites.

The possibility to produce white Eco-cement with the use of a dry method under low-temperature firing of a raw material mixture based on the CaO – SiO2 – Al2O3 – MgO system is shown. Computer calculations were performed and an analysis of the dependence of the characteristics of cement clinker on the quantitative ratio of raw components was carried out. A new composition of the raw material mixture with a decrease of 19 wt. % amount of the carbonate component and, accordingly, CO2 emissions during combustion was determined. The peculiarities of phase transformations in the material during firing with a maximum temperature of 1100 ᵒС when microtalcum was introduced into the initial mixture with the formation of pericloze, ockermanite and merwinite as a factor in the structure and properties of cement clinker were noted.

The possibility to produce white Eco-cement with the use of a dry method under low-temperature firing of a raw material mixture based on the CaO – SiO2 – Al2O3 – MgO system is shown. Computer calculations were performed and an analysis of the dependence of the characteristics of cement clinker on the quantitative ratio of raw components was carried out. A new composition of the raw material mixture with a decrease of 19 wt. % amount of the carbonate component and, accordingly, CO2 emissions during combustion was determined. The peculiarities of phase transformations in the material during firing with a maximum temperature of 1100 ᵒС when microtalcum was introduced into the initial mixture with the formation of pericloze, ockermanite and merwinite as a factor in the structure and properties of cement clinker were noted.

The work shows that there is no significant change in the phase composition of composites with a change in the synthesis temperature, so we can use pre-synthesized heats at a temperature of 950 oC to obtain hot-stamped aluminum-based composites. The best characteristics of the synthesized titanium carbide were obtained for the composition 45Al-11C-44Ti (%, wt.). The lattice period of titanium carbide for this sample is 0.4324, and the particle size of titanium carbide formed after sintering is 0.8-1.5 μm. The influence of the component composition of the initial charge on the features of the structure and the phase composition of the thermally synthesized heat of the Al-C-Ti system was established.

To create a high-hardness and wear-resistant coating on the heat-resistant aluminum AK4 alloy, the technology of microarc oxidation is used. The possibility of forming an oxide layer on the surface (mainly of α−Al2O3 and γ−Al2O3 phases) with a thickness of about 150 μm and a hardness of 17000 – 18000 MPa is shown. For this, the process of microarc oxidation was carried out at a current density of 20 A/dm2 in an electrolyte of the composition KOH (1-2 g/L) and Na2SiO3 (6-12 g/L). The obtained properties of MAO coatings on the AK4 alloy make it possible to effectively use such materials for engine elements.

Sn-Ag powder alloy of eutectic composition is demanded in the production of powders for soldering pastes used in electronics. Non-eutectic alloy has found its application in catalysis for CO2 reduction, in 3D printing, as the promising material for lithium ion batteries. In this work the way of synthesis of Sn–Ag nanostructured powder alloy with near-eutectic composition based of cementation reaction in the system Sn0/Ag+ in aqueous solutions was proposed. The peculiarities of alloy powder synthesis in acid and slightly acid solutions were studied. Factors influencing on powder microstructure, phase and elemental composition were identified. Electrochemical behavior of tin in aqueous solutions for silver deposition was studied by potentiometric method.

Powder high-entropy alloys (HEA) of TiCrFeNiC equioatomic composition were synthesized by hot forging (HF). The phase composition and parameters of the fine structure of the alloys are determined. It is shown that at all annealing temperatures of the alloys their phase composition does not change significantly and consists of two solid solutions of substitution – FCC and BCC and two carbide phases – TiC and Cr3C2. The mechanical properties of the alloys are at a rather high level – so the maximum strength of the alloy was 2243 MPa and the hardness is more than 62 HRC, which can be explained by the effect of high entropy and in situ synthesis of carbides in the manufacture of alloys.

The low-temperature method of Sn–Ni–Zn powders synthesis by cementation of tin and nickel with zinc powder from acidic solutions with the formation of “zinc core – porous nickel shell – external tin layer” structures has been proposed. The method provides metals ratio control in wide ranges (7–41 at. % of tin, 38–86 at. % of nickel and 7–24 at. % of zinc) by variation of the process duration. X-ray phase analysis data give evidence on the presence of β-Sn and Zn phases as well as NiZn3 and NiSn intermetallics in the powders obtained. Differential scanning calorimetry data show the availability of Sn–Zn eutectic with the melting point at 171.2 °C in the powders with high tin content (30–40 at. %). The formation of the ternary intermetallic τ1 phase (Ni3+xSn4Zn) has been established to occur as a result of the powders heating at 260 °C. The discovered low-temperature phase transformation in Sn–Ni–Zn system at 260 °C is of interest for electronic equipment assembly processes that include consecutive stages of soldering and resoldering.

Equiatomic alloys TiCrFeNiCuC were made by two methods of powder metallurgy – vacuum sintering and hot forging followed by annealing. In the process of sintering the TiCrFeNiCuC blanks, the influence of entropy of mixing resulted in the formation of solid substitution solutions mainly on the basis of the FCC lattice, and also formed titanium carbide (TiC0.74). In samples obtained by hot forging and subsequent annealing, two carbides TiC and Cr3C2 were found, and titanium carbide being formed with lower carbon content (TiC0.58). In addition, the forged samples showed significantly higher values of the defect of the crystalline structure, which leads to increase in their hardness.

The possibility of control of efficiency of different factors of high voltage electric discharge (HVED) impact on Ti – Al – С powders system for aimed synthesis of dispersion-hardening components is shown. Nanolaminate-composite Ti₃AlC₂ – TiC with hardness of HV5 = 7 GPa, obtained by consolidation of blend of 85 % Ti + 15 % Al initial composition after HVED with the use of multi-point electrode system has needle structure of Ti₃AlC₂ (a = 0.3068 nm, c = 1.844 nm) with size up to 10 μm, and TiC dispersion-hardening phase (a = c = 4.4331 nm) with particle size no more than 1 μm is situated between grains of Ti₃AlC₂. Dynamic strength of specimens depending on electrode system used during HVED treatment of blend variated in range from 160 to 620 MPa, Young modulus – from 13 to 22 GPa at deformation rate from 600 to 900 s–1. Material has high levels of heat resistance, relative change of mass is no more, than 0.001.

Quantitative analysis of the phase composition of the Ti-Al-V-Mo-Zr system alloys was carried out during operation using the Thermo-Calc program (TCW5 version, TTTI3 database). Polythermal and isothermal cuts are plotted, design temperature values of liquidus, solidus and transition into β-field during heating are given. Regarding the titanium alloy of the Ti-Al-V-Mo-Zr system the effect of annealing temperature on the microstructure of the alloy as well as on the alloying elements content in α and β–phases was studied using the scanning electron microscopy method.

Quantitative analysis of the phase composition of the Ti-Al-V-Mo-Zr system alloys was carried out during operation using the Thermo-Calc program (TCW5 version, TTTI3 database). Polythermal and isothermal cuts are plotted, design temperature values of liquidus, solidus and transition into β-field during heating are given. Regarding the titanium alloy of the Ti-Al-V-Mo-Zr system the effect of annealing temperature on the microstructure of the alloy as well as on the alloying elements content in α and β–phases was studied using the scanning electron microscopy method.