Influence of Test Conditions on the Lubricated Friction and Wear Behaviour of Al–25Zn–3Cu Alloy

The friction and wear properties of Al–25Zn–3Cu alloy were investigated over a range of oil flow rate, pressure and sliding speed using a pin-on-disc machine, after examining its microstructure and mechanical properties. The results obtained were compared with those of a conventional-bearing material (SAE 65 bronze). It was observed that the microstructure of the Al–25Zn–3Cu alloy consisted of aluminium-rich α, eutectoid α + η and θ phases, while the microstructure of the SAE 65 bronze revealed copper-rich α, and eutectoid α + δ phases. It was found that the friction coefficient, temperature and wear volume of both the alloys decreased sharply with increasing oil flow rate and attained almost constant levels beyond a certain range of oil flow rate. It was also found that the friction coefficient and the wear volume of the alloys decreased with increasing pressure, but was observed to be almost independent of the sliding speed. The Al–25Zn–3Cu alloy exhibited higher wear resistance as compared to that of the bronze under all the test conditions. Smearing type of adhesion appeared to be the most effective wear mechanism for the Al–25Zn–3Cu alloy, while abrasion dominated one for the SAE 65 bronze.     

Production and Heat Treatment of Ti6–Al5.5–V–1.8Sn Powder Titanium Alloy

The mechanical properties of Ti6–Al5.5–V–1.8Sn powder titanium alloy are investigated as a function of its structure, which, in turn, depends on its production and heat treatment (quenching and aging).     

Influence of microstructure and texture on the corrosion and tribocorrosion behavior of Ti–6Al–4V

In this paper, the corrosion and tribocorrosion behaviors of Ti–6Al–4V alloy having different phase composition, texture and microstructure was investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were performed to evaluate the corrosion behavior. Sliding wear tests under anodic and cathodic polarization conditions were made to assess the tribocorrosion properties. SEM, OM, and XRD were used to characterize the microstructure, texture, and morphology of the samples. The corrosion resistance was found to depend on to the microstructure, as well as the texture of the surface. A bi-modal microstructure and prismatic texture showed the best corrosion behavior. However, when corrosion was coupled to sliding wear (tribocorrosion), the hardness was found to be the controlling factor.     

Influence of plasma nitriding on fretting wear behaviour of Ti–6Al–4V

Plasma nitriding was performed on Ti–6Al–4V samples at 520 °C in two environments (pure nitrogen and a mixture of nitrogen and hydrogen in the ratio of 3:1) for two different time periods (4 and 18 h). Fretting wear tests were conducted on unnitrided and nitrided samples for 50,000 cycles using alumina ball counterbody. Plasma nitriding reduced the tangential force coefficient of Ti–6Al–4V. The samples nitrided for 4 h exhibited higher hardness and lower tangential force coefficient compared to the specimens nitrided for 18 h. The samples nitrided in nitrogen–hydrogen mixture environment exhibited higher hardness and lower tangential force coefficient compared to the specimens nitrided in pure nitrogen. The samples plasma nitrided in nitrogen–hydrogen mixture for 4 h exhibited the highest hardness and the lowest tangential force coefficient. The wear volume and specific wear rate of the plasma nitrided samples were lower than those of the unnitrided samples. A consistent trend was not observed regarding which nitriding condition would result in lower wear volume and specific wear rate at different loads.     

The Influence of the Matrix Microstructure on Abrasive Wear Resistance of Heat-Treated Fe–32Cr–4.5C wt% Hardfacing Alloy

The abrasion wear resistance of Fe–32Cr–4.5C wt% hardfacing alloy was investigated as a function of matrix microstructure. In this study, the alloy was deposited on ASTM A36 carbon steel plates by the shielded metal arc welding (SMAW) process and the as-welded matrix microstructure was changed into ferrite, martensite, and tempered martensite by heat treatment processes. The Pin-on-disk test results show that under low (5 N) and high (20 N) load conditions, the wear resistance behavior of the as-welded matrix sample is 20 and 15% higher, respectively, than the martensitic matrix sample, although the bulk hardness of the as-welded matrix is 5% lower. The ferritic matrix sample has the poorest wear resistance behavior which is less than half of that of the as-welded matrix one. Micro-ploughing, micro-cutting, and micro-cracking are recognized as the micro-mechanisms in the material removal in which the proportion of micro-ploughing mechanism increased by increasing matrix toughness.     

Influence of the Mechanical Seals on the Dynamic Performance of Rotor–Bearing Systems

In this paper, to consider the effects of mechanical seals, a lumped-mass model and the transfer matrix method are used to establish the equations for the dynamics performance of rotor bearing system. The general inverted iteration method is also used to solve the eigenvalue problem of these equations. To check the response of the rotor bearing system under unbalance motivation, the Gauss method is used to calculate the dynamic response of the constrained vibration. The results, based on the dynamic properties calculation of a typical mechanical spiral seal, such as stiffness coefficients and damping coefficients, exert the influence of the mechanical seal on the rotor bearing system of the high-speed machinery. Meanwhile, some structure parameters that may affect the dynamic performance and forced vibration under unbalance motivation of the rotor bearing system considering mechanical seals are analyzed in the paper. The analysis results show that the mechanical seal more or less has effects on the rotor bearing system. The mechanical seal has much more effects on the flexible rotor bearing system than on the rigid one. For instance, in a certain case, if the effects of the mechanical seal were taken into account, the system s critical speed may increase by 70 80%.     

Effect of Micro-scale Y Addition on the Fracture Properties of Al–Cu–Mn Alloy

Rare earth (RE) elements have positive effects on Al alloy, while most research is focused on microstructure and mechanical properties. As important application indices, toughness and plasticity are properties that are sensitive to alloy fracture characteristics, and few research studies have characterized the fracture properties of Al–Cu–Mn alloy on RE elements. The effect of different contents of Y on the fracture properties of Al–Cu–Mn alloy is investigated. T6 heat treatment (solid solution and artificial aging treatment), optical microscope (OM), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) methods are applied to the alloy. Results showed that when Y element is present at 0.1%, the section of the as-cast alloy has smaller sized dimples and the fracture mode presents ductile features. Slight changes in hardness are also observed and maintained at about 60 HV. With increasing content of the RE element Y from 0.1 to 0.5%, the θ phase and Cu atoms in the matrix were reduced and most stopped at Grain boundaries (GBs). Micro-segregation and an enriched zone of Y near the GBs gradually increased. At the same time, the inter-metallic compound AlCuY is aggregated at grain junctions causing deterioration of the micro-structure and fracture properties of the alloy. After T6 treatment, the flatness of the fracture surface was lower than that of all the as-cast alloy showing lots of dimples and teared edges with a significant increase in hardness. When Y content was 0.1%, the strength and hardness of the alloy increased due to refinement of the grain strengthening effect. The content of Y elements segregated in the inter-dendritic zone and GBs is reduced. Plasticity and deformation compatibility also improved, making cracks difficult to form and merge with each other along adjacent grain junctions and providing an increased potential for ductile fracture. This paper proposes the addition of RE Y as an effective and prospective strategy to improve the fracture properties of the Al–Cu–Mn alloy and provide a meaningful reference in terms of improving overall performance.     

Influence of Parameters of Reactive Magnetron Sputtering on Tribomechanical Properties of Protective Nanostructured Ti–Al–N Coatings

The influence of substrate temperature and bias voltage on the structure and tribomechanical properties of the Ti–Al–N coatings obtained by reactive magnetron sputtering technique has been investigated. The structure and elemental and phase compositions have been studied by scanning electron microscopy, Rutherford backscattering, and X-Ray diffraction. The results of friction and wear experiments indicated that the lowest coefficient of friction (three times lower than 12Cr18Ni10Ti) corresponded to a coating deposited at a bias voltage of–200 V and a substrate temperature of 340°С, while the most wear-resistant coating (under a load of 700 mN and the testing time of 1080 s) was Ti–Al–N sputtered at a bias voltage of–200 V and a substrate temperature of 440°С.     

Influence of Heat Treatment on the Properties of Nickel–Chromium–Silicon Bronze Wire

The selection of optimal heat-treat conditions for nickel–chromium–silicon bronze wire used in the production of helical compression springs is considered. In experiments, the microstructure of samples after aging at 440–480°C is investigated. Tensile tests are conducted.     

Influence of the microstructure of Al–Si alloy on the surface-layer quality in microarc oxidation

The properties of the hardened surface layers formed by microarc oxidation on Al–Si alloy billet are investigated. The microhardness, thickness, and porosity of the surfaces formed depend on the alloy structure.     

Influence of counterbody material on fretting wear behaviour of surface mechanical attrition treated Ti–6Al–4V

Surface mechanical attrition treatment (SMAT) was carried out on Ti–6Al–4V. Fretting wear tests were conducted using two counterbody materials (alumina and steel). SMAT resulted in surface nanocrystallization. Due to high hardness, low tangential force coefficient (TFC) and more TiO₂ layer, fretting wear resistance of SMAT treated samples was higher than that of the untreated samples. TFC values obtained with alumina counterbody were higher than those obtained with steel counterbody. The fretting wear resistance of untreated and treated samples fretted against alumina was lower than that of the samples fretted against steel due to tribochemical reactions at the contact zone.     

Influence of Input Acceleration of Broad-Band Random Vibrations on the Amplitude–Frequency Characteristics of Hydraulic Bearings

Russian Engineering Research - The amplitude–frequency characteristics of hydraulic bearings under the action of broad-band random vibrations with different input root-mean-square...     

Influence of the electromagnetic gap in gas–magnetic bearings on the output characteristics of high-speed rotor systems

The electromagnetic gap in gas–magnetic bearings has a considerable influence on the output load and rigidity characteristics of high-speed rotor systems, as shown by experiments and simulation.     

Influence of the Addition of Vanadium Nitride on the Structure and Specifications of a Diamond–(Fe–Cu–Ni–Sn) Composite System

This article discusses the influence of the addition of vanadium nitride on the mechanical and operational properties of diamond composite material based on metallic bond comprised of iron, copper, nickel, and tin obtained by sintering in a mold at 800°C for 1 h with subsequent hot repressing. It has been established that the addition of vanadium nitride in the amount of 2 wt % to diamond–(51Fe–32Cu–9Ni–8Sn) increases the ultimate compressive strength from 846 to 1640 MPa and bending strength from 680 to 1120 MPa, as well as decreases the wear intensity of the composite material from 0.0069 to 0.0033 g/km. The mechanism of improving the tribological properties has been revealed.     

Influence of Cavitation on the Working Surfaces of the Cylinder–Piston Group in a Diesel Engine during Maintenance

Russian Engineering Research - When a diesel engine runs on water–fuel emulsion, carbon deposits break down on account of microimpact by the fuel droplets in the emulsion. The evaporation of...     

Influence of Calf Serum on Fretting Behaviors of Ti–6Al–4V and Diamond-Like Carbon Coating for Neck Adapter–Femoral Stem Contact

Influences of newborn calf serum on the fretting behaviors of Ti–6Al–4V and diamond-like carbon coating were investigated using a fretting-wear test rig with a cylinder-on-flat contact. The results indicated that, for the Ti–6Al–4V/Ti–6Al–4V contact, the friction coefficients were high (0.8–1.2) and the wear volumes presented an increase with the increase in the displacement amplitude under dry laboratory air conditions. Under serum-liquid conditions, the Ti–6Al–4V/Ti–6Al–4V contact presented significantly larger wear volumes under the displacement of ±?40 µm; however, it presented significantly lower friction coefficients (0.25–0.35) and significantly smaller wear volumes under the displacement of ±?70 µm. For the DLC coating/Ti–6Al–4V contact, the coating response wear maps could be divided into two areas: the coating working area (low normal force conditions) and the coating failure area (high normal force conditions). In the coating working area, the DLC coating could protect the substrate with low friction, low wear volume, and mild damage in the coating. The presence of serum had a positive influence on the tribological performance of the DLC coating. Furthermore, the positive influence was more significant under larger displacement amplitudes condition.     

Effect of Titanium and Nitrogen Additions on the Microstructures and Three-Body Abrasive Wear Behaviors of Fe–B Cast Alloys

This study investigates the effect of titanium and nitrogen elements on the microstructures and wear behaviors of medium carbon Fe–B cast alloy. The as-cast microstructures of Fe–B cast alloy consist of the eutectic boride, pearlite, and ferrite. Moreover, the as-cast eutectic boride structures are greatly refined when titanium and nitrogen are added. The boride area fraction, average boride area, Rockwell hardness, etc., are also investigated systemically. The wear behaviors of medium carbon Fe–B cast alloy are studied by a three-body abrasive wear tester. The results show that the wear weight loss of Fe–B cast alloy with titanium and nitrogen elements is lower than that of the ordinary Fe–B cast alloy. Meanwhile, the wear mechanism of Fe–B cast alloy with different titanium and nitrogen concentrations is described and analyzed.     

Influence of the blank’s properties on the hybrid drawing of long profiles

Hybrid drawing is considered: specifically, preliminary deformation with the formation of longitudinal chip-separation channels and subsequent cutting. Optimal tool characteristics are established for each stage in drawing ductile materials and regular materials.