Mixture Of Granules Research Articles

Study of patterns and mechanisms of combustion of powdered and granulated T-C-B system

Experimental studies of the combustion patterns of the ternary system (100 – x)(Ti + C) – x(Ti + 2B) of bulk density in powder and granular form used for the synthesis of composite ceramics TiC–TiB2 were carried out. The study shows that the dependence of the powder mixture combustion rate on the Ti + 2B content has a non-monotonic character, which is associated with the influence of impurity gas release on the combustion process. By removing the influence of impurity gas by granulation, a monotonic dependence with two characteristic sections was obtained. For the granulated mixture, an increase in the Ti + 2B content 60 wt. % leads to a change from the conductive combustion mode to the convective one, accompanied by a sharp increase in the combustion rate. For the conductive combustion mode, the combustion rate of the substance inside the granule and the combustion transfer time from the granule to the granule were determined, which allowed us to estimate the inhibitory effect of impurity gas release on the combustion rate of powder mixtures of different composition. For the convective combustion mode, it was shown that a decrease in the content of the gasifying additive in the mixture (granulation with ethyl alcohol) led to an unexpected result: an increase in the combustion rate of the mixture. For compositions with (Ti + 2B) 60 wt. % the combustion rate with counter filtration of impurity gases was determined for the first time, which made it possible to estimate the front rate increase according to the filtration combustion theory. According to XRD results, the combustion products of all compositions contain only two main phases TiC and TiB2.

Effect of TaC content on microstructure and wear behavior of PRMMC Fe-TaC coating manufactured by electrospark deposition on AISI304 stainless steel

The Fe-TaC coatings on stainless steel by electrospark granule deposition in an anode mixture of iron granules and tantalum carbide powder were first obtained. The material deposition rate on the substrate increased with the TaC powder concentration growth in the anode mixture, facilitating the initiation of electrical discharges. X-ray analysis of deposited coatings shows the presence of the TaC, γFe, and αFe phases. The tantalum carbide concentration grows with an increase in the content of TaC powder in the anode mixture, from 2.4 to 14.8 vol%. The dependence of the wear rate of coatings on the concentration of tantalum carbide in the anode mixture had a parabola form, with a minimum of 5 vol%. However, with a further increase in the TaC concentration in the anode mixture, the wear rate of the coatings monotonically increased due to spalling of TaC grains due to a deficiency of the metal binder.

Отримання жароміцного гомогенного сплаву методом пресування та спікання суміші порошків (Nb-21Ti-5Al-10Cr-7Mo) ат. %

Multicomponent high temperature strength alloys of the Nb-Ti-Al system, alloyed with Cr, Zr, Mo and Si, with a specific gravity of 6.3 - 7.4 g/cm3, have proven extremely promising in aviation and space technology. However, their physical and chemical features are associated with the high activity of the components, with a significant difference in melting temperatures (from Tmel. Mo – 2617 °C to Tmel. Al – 660 °C) and different specific gravity (from 10.2 g/cm3- Mo up to 2.7 g/cm3- Al), is a big problem for their production. The long crystallization interval of cast alloys of this system, thermophysical features of their crystallization, determine the possibility of formation of dendritic structures, the development of dendritic liquation and segregation of low- or high-temperature intermetallics and eutectics, the tendency to the formation of crystallization cracks, which reduces the operational characteristics of cast alloys. In this regard, it became necessary to investigate the possibilities of obtaining an alloy by the method of powder metallurgy. The purpose of this work was to obtain a homogeneous alloy, to study changes in the grain structure, phase transformations and mechanical properties of the material at various stages of processing in the process of obtaining a homogeneous alloy structure by powder metallurgy methods. The need to protect powder components from oxidation, formation of nitrides, carbides during technological operations at temperatures above 200 °C (high-purity argon) has been established. The optimal duration of intensive grinding of a mixture of powders and granules of raw materials has been worked out, which makes it possible to control the uniformity of the size of the particles of the mixture components, porosity and homogeneity of the alloy. The optimal duration of grinding is 30 minutes, during which the most homogeneous mixture in terms of particle size is formed. The optimal annealing mode was established, which ensures the achievement of homogenization of the alloy, phase transformations at the boundaries of the contact of component particles, and changes in grain sizes. Microstructural and X-ray structural analysis of the samples was carried out, their microhardness and grain dispersion were determined. Keyword: high-temperature strength niobium alloys, physical and chemical features, powder metallurgy, homogeneity, microstructure, mechanical properties, phase composition.

Influence of Mechanical Activation and Impurity Gas Release on the Macrokinetics of Combustion and the Product Structure in the Ti–C–B System for Pressed Compacts and Granulated Mixtures

Influence of Mechanical Activation and Impurity Gas Release on the Macrokinetics of Combustion and the Product Structure in the Ti–C–B System for Pressed Compacts and Granulated Mixtures

Manufacturing of die blanks from hard alloy granulated mixture and influence of chemical composition of the mixture on technological properties of hard alloy die blanks

The technology of manufacturing dies from a hard alloy granulated mixture includes the following operations: preparation of raw materials, forming of blanks, and subsequent sintering. The preparation of hard alloy mixtures consisting of carbide powders and binder metals is one of the main operations in the production of hard alloys. The properties of the resulting alloys largely depend on the conditions of performing this operation. All operations are interconnected, and any change in technological parameters can lead to a change in the formation of the final material structure and, consequently, its properties. This article discusses the technology of manufacturing and the production process of die blanks from a hard alloy granulated mixture. The results of laboratory studies of the hard alloy mixture, the manufacture, and production tests of die blanks are described.

Correlation between the parameters of material transfer and granulation indexes in mixtures with varying ratios of concentrate to iron ore fines

The production of high-grade fine material or concentrate continues to increase due to the depletion of high-grade ore deposits. In iron ore granulation, fine materials are involved in producing granules through the coalescence process and auto-layering around coarse particles. The effectiveness of granulation depends on the role of each size fraction of the ore mixture and the level of material transfer between size fractions, and it is measured by different granulation indexes, including maximum permeability, granulation effectiveness (x0.5) and mass fraction of fine material or concentrate. This study focused on the correlation between the level of material transfer between size fractions in granulated mixtures and different granulation indexes. Regular iron ore fines were replaced with 10%, 20%, 30% and 40% concentrate, respectively, to produce granules with an optimum moisture content, determined by the maximum permeability from a pilot-scale JPU (Japanese Permeability Unit) pot. The results indicated that the level of material transfer between size fractions can be used as an alternative index to evaluate the granulation effectiveness of ore mixtures. Adding more concentrate increased the formation of mini-granules that grow slowly, which is associated with a sluggish level of material transfer between size fractions. The growth of large granules was also delayed, leading to a small mean size of granules, low bed permeability and low granulation effectiveness or partition coefficient, x0.5. The coefficients of variance for the material transfer level and maximum permeability were comparable, providing an opportunity to replace the commonly maximum permeability with the level of material transfer in the measurement of the granulation effectiveness.

Controlling the composition and nanostructure of Au@Ag–Pt core@multi-shell nanoparticles prepared by co-reduction method

Three types of Au@Ag–Pt core@multi-shell nanoparticles (NPs) were synthesized via a co-reduction reaction from a galvanic replacement reaction (GRR) and a reducing agent, with different feeding ratios of Ag or Pt precursors. The morphology of the core-shell NPs showed a thin multi-shell with a mixture of Ag, void, and Pt granules, and their microstructure was investigated by scanning transmission electron microscopy. The effect of the Ag or Pt precursor feeding ratios on the competition of the two reduction reactions, and the subsequent impact on the nanostructure of Ag-void-Pt multi-shell were discussed. In the case of the sample with a reduced Ag precursor feeding ratio, the thickness of the Ag layer decreased significantly. The oxidation resistance of the Ag layer was improved due to the charge-transfer effect from Au to Ag, which suppressed galvanic replacement, and the reaction by the reducing agent was dominant. In the case of the sample with a reduced Pt precursor feeding ratio, the number of Pt granules was found to decrease while the volume of voids was maintained, suggesting that GRR was the dominant reaction in the co-reduction method. These results provide further insight into the co-reduction reaction mechanism and enable the control of noble trimetallic nanoparticles with complex shells.

Electroerosive Series of Metals for Electric Spark Deposition Based on Solving the Problem of Thermal Conductivity

The electrical erosion of Zn, Al, Zr, Ti, V, Fe, Ni, Co, Cr, Nb, Mo, Cu, and W was experimentally determined. For the first time a mixture of granules of the listed metals, taken in equal molar ratios, was used that acted as a non-localized electrode for the electric spark deposition of steel 35. A mathematical model is proposed so as to calculate the volume of molten metals under conditions of an electric discharge during electric spark deposition based on solving the problem of the thermal field on the electrodes using their thermophysical constants. Calculations for a wide range of metals that differ greatly in thermophysical properties allowed to conclude that the active heat source during a discharge is an order of magnitude narrower than the erosion zone and three orders of magnitude more powerful than previously theoretically assumed. The volumes of melting on metals per one discharge were calculated and the corresponding series of electrical erosion resistance of metals was constructed. It is shown that the developed theoretical series of electrical erosion resistance of metals better corresponds to experimental data in comparison with literature data.

ТЕРМОДИНАМИЧЕСКИЙ АНАЛИЗ ОКИСЛИТЕЛЬНО – ВОССТАНОВИТЕЛЬНЫХ РЕАКЦИЙ, ПРОТЕКАЮЩИХ ПРИ ГАЛЬВАНОКОАГУЛЯЦИОННОЙ ОЧИСТКЕ СТОКОВ

Abstract. One of the most important environmental problems is the purification of industrial wastewater from heavy metal ions. Various methods are used to solve this problem: chemical, physico-chemical, sorption, but the most promising method for cleaning industrial wastewater containing heavy metal ions, namely copper, nickel and zinc, is the galvanocoagulation method. However, the literature does not sufficiently cover the processes of cementation of heavy metals on cathode loading. A physico-chemical approach to this process is necessary to confirm the process of separation of heavy metal ions from wastewater in the form of sediment and the creation of new industrial wastewater treatment schemes. The composition of the loading is essential in galvanocoagulation neutralization, therefore, in order to determine the effect of the type of active loading, a carbon mineral sorbent (SGN) obtained from ores of cryptocrystalline graphite (Noginsky deposit of the Krasnoyarsk Territory) was used. The studies were carried out in a galvanocoagulation module by passing wastewater through a loading consisting of a mixture of iron shavings and granules of carbon mineral sorbent based on ores of cryptocrystalline graphite (SGN). At the same time, the air dispersed in the lower part of the device was bubbled through the loading. As a result of the operation of the Fe-SGN short-circuited galvanic cell, iron scrap was dissolved and its intensive oxidation to Fe3+ by air oxygen. The article considers the mechanism of galvanocoagulation neutralization of wastewater based on thermodynamic analysis of redox reactions occurring during galvanocoagulation wastewater treatment.
 Subject of the study: both model and real wastewater from the production of electroplating coatings containing copper, zinc and nickel ions with the following concentrations were used: =60 mg/dm3; =15 mg/dm3; =20 mg/dm3
 Materials and methods: galvanocoagulation neutralization using a short-circuited Fe-SGN galvanic cell (carbon mineral sorbent)
 Results: the physico-chemical patterns of the galvanocoagulation process of wastewater treatment have been studied and the thermodynamic parameters of heavy metal ion reduction reactions have been determined
 Conclusions. It has been experimentally established that it is possible to intensify the process of galvanocoagulation of wastewater containing heavy metal ions by using a carbon mineral sorbent as a cathode loading, which reduces the processing time with a high purification effect and a difficult-to-dissolve precipitate is formed.

Self-replicating segregation patterns in horizontally vibrated binary mixture of granules

Fluidized granular mixtures of various particle sizes exhibit intriguing patterns as different species segregate and condense. However, understanding the segregation dynamics is hindered by the inability to directly observe the time evolution of the internal structure. We discover self-replicating bands within a quasi-2D container subjected to horizontal agitation, resulting in steady surface waves. Through direct observation of surface flow and evolving internal structures, we reveal the crucial role of coupling among segregation, surface flow, and hysteresis in granular fluidity. We develop Bonhoeffer-van der Pol type equations grounded in experimental observations, reproducing complex band dynamics, such as replication, oscillation, and breathing. It suggests the similarity between pattern formation in granular segregation and that in reaction–diffusion systems.

Vibrational manipulation of dry granular materials in lab-on-a-chip devices.

We present vibrational techniques to pump, mix, and separate dry granular materials using multifrequency vibrations applied to a solid substrate with a standard audio system. The direction and velocity of the granular flow are tuned by modulating the sign and amplitude, respectively, of the vibratory waveform, with typical pumping velocities of centimeters per second. Different granular materials are mixed by combining them at Y-shaped junctions, and mixtures of granules with different friction coefficients are separated along straight channels by judicious choice of the vibratory waveform. We demonstrate that the observed velocities accord with a theory valid for sufficiently large or fast vibrations, and we discuss the implications for using vibrational manipulation in conjunction with established microfluidic technologies to combine liquid and dry solid handling operations at sub-millimeter length scales.

Using viscosity as an index for polymer loading of bentonite-polymer composite geosynthetic clay liners

Bentonite-polymer composite (BPC) geosynthetic clay liners (GCLs) containing a mixture of air-dry granules of bentonite and polymer have been developed for containment of wastes that generate leachates that are too aggressive for conventional sodium bentonite GCLs. Sufficient polymer loading is essential for BPC GCLs to maintain low hydraulic conductivity, and expedient methods are needed for manufacturing quality control and construction quality control to confirm that BPC GCLs contain sufficient polymer. In this study, a methodology for developed to estimate the polymer loading based on viscosity testing of slurries prepared with the BPC. A simplified version of the method can be used to determine if polymer is present in a BPC. Factors influencing the viscosity measurement were evaluated systematically, including water-to-BPC ratio, tempering time, and mixing method. The method that was developed consists of (1) adding deionized water to dry BPCs to achieve a water-to-BPC ratio of 30, (2) blending the BPC-water mixture with an overhead stirrer at 5000 rpm for 30 min to create a homogeneous slurry, (3) tempering the slurry in a zip-top bag for 24 hr, and (4) measuring the viscosity of the slurry in a viscometer at 300 and 600 rpm. Linear relationships were developed between polymer loading and viscosity for two BPC GCLs. Independent validation confirmed that the polymer loading estimated with the method is ±0.25% of the actual polymer loading.

The effect of LC50 granula mixed extracts of Coriandrum sativum L. and Allium sativum on mortality of Larvae of Aedes aegypti L. causing dengue fever

Aedes aegypti L. is a type of mosquito that has the potential to be a vector for carrying Dengue Hemorrhagic Fever (DHF). It is necessary to control mosquito vectors with environmentally friendly materials, namely natural larvicides such as coriander (Coriandrum sativum L.) and garlic (Allium sativum). This study aims to determine the LC50 of a mixture of coriander and garlic extract granules on the mortality of Aedes aegypti L. mosquito larvae as a vector for dengue hemorrhagic fever within 48 hours. Extract preparation was carried out using the maceration method with 70% ethanol solvent then evaporated to obtain a thick extract. Granules were made using aerosol and avicel in a ratio of 20%: 20%. Serial preparation of granule concentrations is 10 ppm, 25 ppm, 50 ppm, 75 ppm and 100 ppm. Extract granule testing was carried out by inserting 20 larvae into the extract granule concentration which had been dissolved using distilled water at each predetermined concentration. The results of the research show that the higher the concentration used, the higher the death rate of Aedes aegypti L. larvae with the LC50 probit analysis results being 32.95 ppm with a lower limit of 18.22 ppm and an upper limit of 85.09 ppm. This shows that the mixture of coriander and garlic extracts used is toxic to Aedes aegypti L larvae.

İZOSORBİD DİNİTRATIN MODİFİYE SALIM YAPAN ÇOK BİRİMLİ BİLEŞİMİNİN TABLET ŞEKLİNDE BASILMASI VE DEĞERLENDİRİLMESİ

Objective: This study was aimed to create a multiple-unit dosage form of isosorbide dinitrate by pressing spherical matrix granules into tablets, selecting the optimal technology parameters and evaluating the obtained tablets. Material and Method: The tablet cores were prepared from mixtures of active matrix granules and shock-absorbing auxiliary granules in various ratios using diverse tabletting forces. The dissolution profiles of the obtained tablet compositions were evaluated in comparison with the reference preparation. Result and Discussion: An optimal ratio of spheroids with the active component with auxiliary granules along with optimal compression parameters were determined. The resulting as multiple-unit tablets exhibited a release profile similar to that of Cardicket Retard. Used technological approach makes it possible to regulate the dissolution profile of tablets by changing the ratio of active granules with different kinetics of the active substance release.

Vertical Bone Augmentation Using Two Bioactive Glasses in a Rabbit Tibia Model: A Comparative Study with Literature Review

Background: Recently, synthetic materials based on bioactive glasses have been in special demand in dental implantology, which, according to the mechanism of their action, are not only osteo-conductors, but also osteo-inductors. Of even greater interest is the fact that the biological degradation of these materials causes alkalization of the area and inhibits the growth of many pathogens. Considering the unique properties of this group of osteoplastic fillers and the problems associated with healing after guided bone regeneration, this study aimed to compare the effectiveness of using bioactive glasses S53P4 and 45S5 when performing vertical bone augmentation in an experiment applying a rabbit tibia model. Methods and Results: Six adult outbred rabbits aged from 1.5 to 2 years and weighing from 2.5 kg to 3.2 kg were used in the study. A titanium mesh was used to perform a true vertical guided bone regeneration technique. In each animal, two titanium tents were placed: one on the left tibia and one on the right tibia. On the left limb, empty spaces were filled with bioactive synthetic bone filler NovaBone® Morsels (USA); on the right limb, we used a mixture of bioactive glass Bonalive® granules CMF (Finland) and mineralized bone MedPark Bone-D XB (Bovine Xenograft, South Korea) in a ratio of 1:1. The quantity and quality of regenerated tissues were assessed after 8-10 weeks. The NovaBone application has allowed a gain of 2.6±2.67 mm in extra-skeletal hard tissue growth. No signs of guided bone regeneration were observed in all cases of application of an osteoplastic mixture of Bonalive and Bone-D XB granules. Conclusion: Within the limits of this study, it was found that the use of a mixture of bioactive glass Bonalive (S53P4) with bovine hydroxyapatite in a 1:1 ratio was not effective in vertically guided bone regeneration, but the application of NovaBone (45S5) could promote a new bone formation.

Electrospark Cu[sbnd]Ti coatings on titanium alloy Ti6Al4V: Corrosion and wear properties

Nowadays, copper-titanium coatings have invited extensive attention from researchers in the surface modification of industrial and biomedical materials due to their excellent mechanical properties and biocompatibility. The electrospark deposition technique was used for CuTi coatings deposition on the Ti6Al4V alloy by processing in a mixture of copper and titanium granules at a copper concentration from 10 to 90 at.%. For the first time, electrospark CuTi coatings with a wide range of copper and titanium ratios are obtained on Ti6Al4V titanium alloy. It is revealed that both cathode mass gain and coatings thickness rise with the copper concentration increase in the mixture of granules. According to EDS analysis, the copper concentration in the coating linearly grew with a growth of its content in the mixture of granules. According to the data of X-ray analysis, intermetallic compounds were found in the structure of the coatings: CuTi3, CuTi, Cu4Ti3, and Cu3Ti. Detected phases provide the coating microhardness up to 6.7 GPa. Polarization tests in 3.5 % NaCl solution showed corrosion resistance growth with a copper content decrease in CuTi coatings. The oxidation resistance at a temperature of 900 °C grows with an increasing copper concentration in the coating structure. Cu-enriched sublayer is formed on upper layers of Ti6Al4V alloy after CuTi coating oxidation at 900 °C. The wear rate of the coated samples as a function of copper concentration had the form of a parabola, with a minimum for the coating made in an equimolar mixture of copper and titanium. The use of electrospark CuTi coatings makes it possible to increase the wear resistance of the Ti6Al4V alloy surface up to 11 times.

Influence of Inorganic Additives on the Surface Characteristics, Hardness, Friction and Wear Behavior of Polyethylene Matrix Composites.

The aim of this research was to analyze the effect of inorganic additives on the tribological properties of the high-density polyethylene (HDPE) matrix composite surface. Titanium (Ti) and hexagonal boron nitride (hBN) were added in different mass fractions. The samples were produced by pressing a pre-prepared mixture of granules. The composite samples with the following mass fractions of additives were fabricated: 5% hBN, 10% hBN, 28% Ti-2% hBN, 23% Ti-7% hBN, and 20% Ti-10% hBN. An even distribution of individual additives' concentrations was confirmed. Observations of morphology, surface topography, hardness, and tribological measurements were conducted using reciprocating motion tests with the "pin-on-flat" and rotational tests with the "pin-on-disc" configuration. Subsequently, microscopic observations and measurements of the wear track profile were carried out. Additionally, geometry parameters of the contacting elastic body were calculated for various counter-samples. It was found that the Shore D hardness of samples containing Ti and hBN increased with the Ti content, while the coefficient of friction (COF) value decreased. The addition of hBN alone did not significantly affect the hardness, regardless of the ratio, while the COF increased with the increasing hBN content. The COF value doubled with the addition of 10% hBN (COF = 0.22), whereas the addition of 90% Ti-10% hBN resulted in a decrease in the COF value, to COF = 0.83. The highest hardness value was obtained for the sample containing 28% Ti-2% hBN (66.5), while the lowest was for the sample containing 10% hBN (63.2). The wear track analysis, including its height and width caused by deformation, was detected using a focal differentiation microscope and scanning electron microscopy. Additionally, EDS maps were generated to determine the wear characteristics of the composite.

Electrospark deposition of metalloceramic Fe–Al/HfC coating on steel 1035

To improve the tribotechnical behavior and heat resistance of steel 1035, composite metalloceramic Fe–Al/HfC coatings were prepared by electrospark deposition. A non-localized anode was used as an electrode consisting of a mixture of iron and aluminum granules with a molar ratio of 3:2 and with the addition of HfC powder. The cathode gain had positive values indicating that HfC powder can be deposited on steel 1035 using the Fe60Al40 anode mixture. Moreover, the cathode gain monotonically increased with the increase in addition of HfC powder to the anode mixture. The coatings structure is represented by a matrix of FeAl intermetallic compound reinforced with HfC grains, which corresponds to the structure of a metalloceramic composite. Concentration of HfC in the coating increased with the addition of HfC powder to the anode mixture. Deposition of Fe–Al/HfC coatings according to the proposed technique allows reducing the friction coefficient of steel 1035 from 6 to 40 vol. %. Depending on the concentration of HfC in the anode mixture, the wear resistance of Fe–Al/HfC coatings varied nonmonotonically with a maximum at 8 vol. %. The use of Fe–Al/HfC coatings makes it possible to increase the wear resistance of the steel surface to 10 times. Comparison of the final weight gain of the samples after 100 h of oxidation resistance tests at a temperature of 700 °C allows us to conclude that electrospark deposition Fe–Al/HfC coatings can increase the oxidation resistance of steel 1035 by 1.7–2.2 times. Analysis of the study results shows that adhesion of Fe–Al composition to HfC is weak. This was reflected in decrease in hardness, wear resistance and oxidation resistance of coatings with an increase in the concentration of HfC in the anode mixture above 8 vol. %.

Биосовместимость Ti – Al интерметаллидных покрытий на титановом сплаве Ti6Al4V

Titanium alloy Ti6Al4V is the most common metal material in orthopaedics. However, it is characterized by high elasticity and bioinertness, which makes it difficult to osseointegrate on its surface and leads to aseptic loosening of the implant, has insufficient corrosion resistance and high wear, leading to the accumulation of metal ions and wear particles in the body of patients. To eliminate these shortcomings, a Ti – Al coating was prepared by electrospark processing of the Ti6Al4V alloy in an equimolar mixture of titanium and aluminum granules. The prepared TiAl coating consists of intermetallic phases: Ti3Al, TiAl, TiAl2, and TiAl3, which have higher tribological properties. Thus, the average value of the friction coefficient of the sample with a TiAl coating was 12% lower, and the reduced wear was 2.36 times less than the original Ti6Al4V alloy one in a simulating body fluid. In addition, the deposition of a TiAl coating on the Ti6Al4V alloy makes it possible to increase the corrosion resistance of its surface. Biomedical studies have shown that the deposition of a TiAl coating on a Ti6Al4V alloy increases the resistance of erythrocytes to the hemolytic agent action. Improving the biological activity of the alloy surface during ESA deposition of TiAl coating leads to normal growth of fibroblasts on it without signs of cytotoxity. Treatment of samples with adhered cell culture by a solution of trypsin-Versen led to a reduction in the density of cells in the coating by 42 %, while in the alloy by 60 %. This indicates a better fibroblast attachment to the surface of the Ti-Al coating, compared to the Ti6Al4V alloy.

Осаждение силицида титана на нержавеющую сталь AISI304

Introduction. Metal-ceramic coatings based on titanium silicide are promising for protecting stainless steel AISI 304 from wear, corrosion and high-temperature oxidation. Purpose of the work: to investigate the stainless steel AISI 304 surface layer structure after electrospark deposition in a mixture of titanium granules with silicon powder, and to study oxidation resistance, corrosion resistance and tribotechnical properties of the obtained coatings. Research methodology. Fe-Ti-Si coatings on the stainless steel AISI 304 samples were obtained by electrospark machining with a non-localized electrode consisting of titanium granules and 2.6-6 vol.% mixture of titanium and crystalline silicon powders. Results and discussion: it is shown that a stable positive gain of the cathode is observed when the proportion of silicon in the powder mixture does not exceed 32 vol.%. The phase composition of the coatings includes: a solid solution of chromium in iron, titanium silicide Ti5Si3, titanium and silicon, which is confirmed by the energy dispersion analysis data. The microhardness of Fe-Ti-Si coatings ranges from 10.05 to 12.86 GPa, which is 5-6 times higher than that of uncoated steel AISI 304. The coefficient of friction of the coatings is about 20% lower compared to steel AISI 304 and hovers around 0.71-0.73. Wear tests in dry sliding mode show that Fe-Ti-Si coatings can increase the wear resistance of steel AISI 304 up to 6 times. The oxidation resistance of the coatings at a temperature of 900 ̊С is 7-12 times higher as compared to steel AISI 304. The conducted studies have shown that new electrospark Fe-Ti-Si coatings can increase corrosion resistance, oxidation resistance, microhardness, as well as reduce the coefficient of friction and wear rate of the stainless steel AISI 304 surface.