Papers by Keyword: Tribological Characteristics

Abstract: Steel 1.7220 is widely used in mechanical engineering for heavily loaded components operating at temperatures up to 450 °C. Femtosecond laser processing enables the formation of controlled microstructures without overheating or deformation, reducing the contact area and serving as reservoirs for lubricants. This study aims to evaluate the effect of laser microstructuring (Mesh and LIPSS types) on the tribological properties of steel, particularly under dry lubrication with powder. Micro- and nanostructures were analyzed using optical and scanning electron microscopy. Tribological tests were conducted using the ball-on-plate reciprocating method, with a load of 200 g, a frequency of 2 Hz, and a stroke amplitude of 1 cm for 30 minutes. For LIPSS structures, the influence of the friction direction relative to the orientation of the surface structures was investigated. The change in surface morphology after laser texturing was investigated. The effects of lubrication and surface structuring on tribological properties were analyzed, and the role of periodic structures in enhancing tribofilm stability was demonstrated.

Abstract: The paper describes the influence of the composition of the sealer used to form a composite coating on the surface of a steel sample by electrical discharge machining along the sealing layer on the structure and properties of the coating. The object of this study is samples made of steel 45. All samples are treated by electrical discharge machining with the use of ПР-В3К (Stellite) hard alloy-based anode and modifying sealers, based on CrCNi, TiCNi, and non-stoichiometric W and Mo compounds. Besides, the paper presents the physical and mechanical properties of the obtained coatings, examined during a set of tribological tests. The conducted experiment demonstrated that the wear resistance of coated samples is higher, compared to coatless ones. The strong point of our study lies in functionality to employ sealers, based on the SHS-reagents and non-stoichiometric W and Mo compounds with ESA processing in friction units.

Abstract: Al-Si eutectic system is a class [Mansoor, 2014 #24] of important cast alloys accounting for the majority of aluminum parts for different industrial applications. However, in unmodified form, it attributes to the lower mechanical strength, ductility and wear characteristics. In present work, Al-9 wt. %Si alloy was prepared in unmodified and modified form, where modification was carried out using mixtures of transitional earth halides. The modification process rectified the needle like silicon rich secondary phase into acicular shape, whose effect upon the tribological characteristic of the alloy were studied using pin-on-disc method. It was found that the coefficient of friction was reduced in modified alloy, besides lowering the wear rate. The main feature of wear scar was laminates. In case of modify alloy the laminates were of uniformly formed small sized, as opposed to non-uniform predominately large sized smooth segments with cracked edges. It was postulated that these non-uniform smooth laminates were formed due to smearing resulted in high coefficient of friction and wear rate. The altered tribological characteristics were attributed to the morphology of the silicon rich secondary phase i.e. the acicular shape.

Abstract: Aluminum Metal Matrix Composites (AMMCs) are promising materials for advanced structural, aviation, aerospace, marine, defense applications, automotive and other related sectors because of their excellent combination of properties. The AMMCs is fabricated by using stir casting method, which is the simplest way of fabricating a material. In this paper aluminium alloy 6061 is been reinforced with SiC along with fly ash and neem leaf ash. The three samples have been fabricated they are Sample1 (Al85%+SiC15%), Sample2 (Al 85%+SiC5%+FlyAsh10%) & Sample3 (Al85% +SiC5%+ Neem leaf ash10%). After fabricating this three sample the following test are conducted like Hardness test, Microstructure Test, Friction and Wear Test. The wettability of SiC and Neem leaf ash particles in the matrix was improved by adding them. The optical and scanning electron micrographs showed a homogeneous dispersion of composition material. The result shows that the Sample-3 (Al80% +SiC10%+ Neem leaf ash10%) shows improvement in mechanical properties like hardness, the wear properties has been reduced and their Micro structural characterization clearly shows uniform distribution of SiC and Neem Leaf ash in the composition.

Abstract: The Metal Matrix Composites (MMCs) especially Aluminum based systems have unique advantages of having superior mechanical, chemical and electrical properties, in addition to light weight and high stiffness. In this work, composites comprising of Aluminum with varied concentrations of Cenospheres as reinforcement was produced by Powder Metallurgy (PM) route. The densification of the composites was effected both by conventional and Microwave (MW) sintering techniques. The microstructures of the sintered samples were observed through scanning electron microscope (SEM) and phases by x ray diffraction technique (XRD), followed by evaluation of tribological parameter namely slide wear behavior and solid particle erosion resistance. The densities and the Brinell hardness values for the samples were also evaluated. The results showed that microwave sintered samples exhibited higher hardness, lower erosion and slide wear loss.

Abstract: Studies on the structure and the phase composition of the deposited material were carried out using methods of X-ray structure analysis and electron diffraction microscopy of extract coal replicas and thin foils on steel Hardox 400. Formation of a multiphase state, represented by grains of α-iron and inclusions of carbide phases based on iron, chromium, and niobium, is revealed.

Abstract: Nanostructured Al2O3-13wt.% TiO2 coatings were prepared by plasma spraying using agglomerated nanocrystalline powders via a spray drying method. The as-sprayed coatings and their worn surface were characterized using scanning electron microscope (SEM). The tribological characteristics were evaluated on block-on-ring configuration. It is found that that the nanostructured coating exhibited a unique bimodal microstructure, which has an important influence on the tribological characteristics. The abrasive wear resistance of the nanocoatings are greatly improved compared with the conventional coatings, and the abrasive wear mechanism is also discussed.

Abstract: Tribological study on a 12.7 mm diameter steel ball bearing specimen has been carried out in a four-ball machine. The synthesis of 3-(N-n-octadecylammonium) quinazolin-4-ones was described. The 3-(N-n-octadecylammonium) quinazolin-4-ones has been found to be quite effective as a potential ashless additive without phosphorus and sulphur in liquid paraffin according to the experimental results. Employing scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), the film formed when the the additive interreacted with the metal was investigated.

Abstract: The paper presents selected results of tribological tests on ball bearings. The elements for tests were obtained from their manufacturer. Two groups of ball bearings were evaluated: 134-781TNG-2RS and CBK 441TNG. Tribological tests were conducted with SMT-1 device in two-stage cycle. The first stage involved tests based on the authors’ own method. In the second stage the tests were conducted according to the manufacturer’s recommendations (methodology). The obtained results indicate varied tribological characteristics of the tested ball bearings, both in reference to the parameters of the external function and the applied test method.

Abstract: This study demonstrated nanoindentation techniques of investigating the effects of size and feature in a microstructure on the mechanical properties of rheology-forged aluminum alloy. Mechanical properties and tribological characteristics of rheology-forged Al2024 wrought aluminum alloy in terms of T6 heat treatment were investigated by varying the aging time by nanoindentation and nanoscratch techniques. By nanoindentation/nanoscratch tests and atomic force microscopy, it was demonstrated that the 4 hour aged material exhibites the highest hardness because of the intermediate precipitate phase θ″, which was precipitated by T6 heat treatment at 495°C. Moreover, the friction coefficients in the precipitates in the eutectic phase region were lower than those in the primary α phase region.