Engineering Journal of Satbayev University

Mechanical and tribological behavior of multilayer and monolayer TiN-based coatings

B.K. Kenzhaliyev — 2025-06-30

This study investigates the mechanical and tribological properties of monolayer TiN coatings and multilayer TiN/TiCN coatings deposited via direct current magnetron sputtering onto titanium substrates (VT1-0). The coatings were characterized by microstructure, nanohardness, elastic modulus, and tribological performance under lubricated friction conditions. Scanning electron microscopy (SEM) revealed that the coatings exhibit a uniform microstructure without visible defects and a typical columnar growth morphology. Nanoindentation tests demonstrated that the multilayer TiN/TiCN coatings possess enhanced hardness (up to 23.5 GPa) and elastic modulus (191 GPa) compared to the monolayer TiN, attributed to interlayer strengthening effects and redistribution of residual stresses. Tribological tests using a ball-on-disk configuration under lubricated conditions showed that the multilayer coatings exhibit a significantly lower coefficient of friction (0.10–0.13) and improved wear resistance compared to the TiN coating. This behavior is associated with TiCN layers, which reduce interfacial adhesion, promote uniform load distribution, and facilitates the formation of a protective tribofilm. The results confirm that the TiN/TiCN multilayer coatings offer superior mechanical and tribological properties, making them promising candidates for engineering components operating under friction and wear conditions.

Overview of oxide electrode materials for lithium–ion batteries

M. Dyussembayev — 2025-06-30

The article discusses the prospects for developing lithium-ion batteries, emphasizing lithium-enriched transition metal oxides used as cathode materials for lithium-ion batteries (LIB). The primary focus is on materials with the formula xLi₂MnO₃⋅(1−x)LiMO₂ (where M=Mn, Ni, and Co) that exhibit high discharge capacity (over 250 mAh/g) and specific energy (over 950 Wh/kg), surpassing traditional cathode materials such as LiCoO₂, LiMn₂O₄, and LiFePO₄. These oxides combine the monoclinic phase of Li₂MnO₃ and the trigonal phase of LiMO₂, which ensures their high performance. However, the authors note several problems, including low speed characteristics, irreversible capacity of the first cycle, and degradation of voltage and capacity during cycling. These problems are linked to the creation of spinel-like structures, unwanted reactions at the surface with the electrolyte, and the release of oxygen. The authors propose modification methods like protective coatings, alloying, and the creation of composite structures to enhance the characteristics. The article also includes an overview of other common cathode materials such as LiCoO₂, LiMn₂O₄, LiNiO₂ and their combinations, highlighting their advantages and limitations. Special attention is paid to promising materials, including LiNi₁/₃Co₁/₃Mn₁/₃O₂ and LiFePO₄, which have balanced electrochemical and economic properties. It was also emphasised that further research is needed to understand the degradation mechanisms and optimise the structure of lithium-enriched oxides. Resolving these issues can help create better and more reliable cathode materials for LIB, which is crucial for advancing electric vehicles and other energy-intensive technologies.

Features of mineral formation in the structure of iron ore materials from the position of the state diagram of the system CaO–Fe2O3–SiO2

А. Zhunusova — 2025-06-30

This paper presents the results of a study of the strengthening of iron ore raw materials obtained by oxidative roasting of granules and pellets using gaseous fuel and agglomeration with combustion of solid fuel in the agglomeration layer. Differences in the mechanisms of mineral formation of granules, pellets and agglomerates appear at the stage of liquid-phase strengthening and are due to the different role of iron in forming the strengthening melt. At the same time, in the agglomerate, granules and pellets, iron is in different valence states, affecting the processes' features. Iron can be in a trivalent state in the iron-silicate melt of granules and pellets and is not a silicate-forming component of the charge. The silicate compositions of the binders in the entire studied range of basicities (0.3-1.5) are located along the line of the CaO–SiO₂ connection, which is determined using the phase diagram of the CaO–Fe₂O₃–SiO₂ system. During agglomeration, the silicon-containing melt is formed under conditions of excess FeO, which directs the process of mineral formation during the creation of the iron-silicate binder of the agglomerate. Under standard agglomeration conditions, silicate binders with a basicity of 1.0-1.5 are formed in the olivine field of the CaO–FeO–SiO₂ phase diagram, covering a wide range of compositions. The processes of mineral formation in batches, by hardened methods, both during the firing of granules, pellets, and during agglomeration, have shown that changing the oxidation potential of the gas phase is an effective lever on the path not only to improving the properties of ferrous sand - a waste product of alumina production, but also to creating both new binders and new types of iron ore raw materials suitable for smelting ferrosilicon.

Assessment of the ventilation system and solutions for improving the ventilation network at Khe Cham Coal Mine, Vietnam

C.H. Nguyen — 2025-06-30

Ventilation for underground mines plays an essential role in production activities by ensuring labor safety and maintaining environmental conditions. Mine ventilation is also one of the most effective methods for preventing methane gas and coal dust explosions. Therefore, it is necessary to investigate the ventilation network annually and calculate the overall ventilation requirements for underground mines in the Quang Ninh coalfield. Based on the production plan and ventilation needs of the Khe Cham Coal Mine, the authors surveyed and evaluated the mine ventilation network, thereby proposing solutions to improve the ventilation system and calculating the ventilation parameters for 2025. To achieve the research results presented in this article, the authors used methods such as data collection, analysis and synthesis, field surveys, result analysis and evaluation, combined with numerical modeling using ventilation software to verify calculation results. To ensure ventilation for Khe Cham Coal Mine in 2025, two main fan stations – №1 at level +35 and №2 at level +112 should be operated jointly, with the following calculated working modes: fan station №1 at level +35: airflow of 193.72 m³/s, air pressure of 448 mmH₂O, impeller angle of 40°; fan station №2 at level +112: airflow of 155.8 m³/s, air pressure of 419.5 mmH₂O, impeller angle of 35°. Based on the analysis of data collected at the Khe Cham Coal Mine, the paper assesses the overall ventilation status of the mine. It proposes solutions to improve the ventilation network, ensuring safety during production activities. Additionally, it determines the combined working mode of the two main fan stations, providing a foundation for developing the general ventilation plan for Khe Cham Coal Mine in 2025.

Innovative approaches to the processing of ash and slag materials from the fuel and energy sector in the context of sustainable development

S.M. Nurmakova — 2025-06-30

The whole world aims to reduce coal consumption, but despite such a policy, there are countries where its consumption continues to grow (China, India). If coal consumption grows, the volume of ash and slag waste (materials) that must be utilized and processed to obtain final products grows. The main elements included in the by-product of coal combustion are SiO₂, Al₂O₃, and Fe₂O₃. The paper provides a review of the use and processing of ash and slag materials for recycling as well as potential directions for their disposal: as well as potential directions for their disposal: cement production, geopolymer, in zeolite synthesis, microsphere separation, in agriculture, in land reclamation, in phytoremediation as reagents for water purification, in road construction for backfilling abandoned mines. The authors employed physicochemical analysis methods to confirm that the primary components of the material are SiO₂ (65.9%) and Al₂O₃ (22.5%). It has been established that a high proportion of silicon and aluminum can be an effective raw material for construction and geopolymer materials, as well as in the production of ceramic products. Availability of Fe₂O₃ (5.54%) suggests possibilities for its use in catalytic processes and pigment production. The alkaline reaction of the aqueous extract of the ash (pH = 9.25) correlates well with its chemical composition and confirms the presence of active alkaline components in the material. This alkaline nature of the ash favors geopolymerization processes and increases the material's reactivity when interacting with acidic activators. Additionally, the minor presence of TiO₂ (1.11%) may improve the mechanical properties of ash-based materials.

Monitoring of the water and salt balance of the Bakbakty rice irrigation system under reuse of collector-drainage water for irrigation

M. Absametov — 2025-06-30

This study presents the methodology, approach, and results of calculating the components of water and salt balances based on three years of field research on the reuse of collector-drainage water in the Tasmurun area of the Bakbakty irrigation system, under arid and low-water conditions typical for water-demanding rice fields. Balance calculations were based on data from in situ observations with active involvement of local farmers, ensuring data reliability. The water balance showed a slight negative discrepancy ranging from 0.4-0.6% in 2022 and 0.001-0.02% in 2023-2024, confirmed by groundwater level monitoring and maps. The salt balance showed a slight accumulation, with values from +0.016 to +0.29 t/ha in field No. 2 and +0.049 to +0.089 t/ha in field No. 4. Seasonal salt increases were linked to leaching regimes and the dominance of easily soluble salts, posing no threat to land reclamation status.