Search Results (5)

The anodic oxide layer’s porosity is considered a functional feature, acting as a reservoir of lubricants. This feature enables the design of self-lubricating systems that effectively reduce friction and wear. To improve the tribological performance of Al₂O₃ anodic coatings on EN AW 5251 aluminium alloys, this paper presents a modification of the coating with tungsten disulfide (IF-WS₂) nanopowder and its effect on coating resistance. The wear properties of Al₂O₃/IF-WS₂ coatings in contact with a cast iron pin were investigated. The results include the analysis of the friction coefficient in the reciprocating motion without oil lubrication at two loads, the analysis of the wear intensity of the cast iron pin, the characterisation of wear scars, and the analysis of SGP parameters. Two-level factorial analysis showed that load and nanomodification significantly affected the load-bearing parameter Rk. Incorporation of the modifier, especially under higher loads, reduced the Rk value, thus improving the tribological durability of the contact pair. Both load and nanomodification had a notable impact on the coefficient of friction. The use of IF-WS₂-modified coatings reduced the coefficient, and higher loads further enhanced this effect, by approximately 9% at a load of 0.3 MPa and 15% at a load of 0.6 MPa, indicating improved lubricating conditions under greater contact stress. Full article

The present work epitomises extracting the graphite (Gr) solid lubricant from the corn stover. The extracted Gr was incorporated as reinforcement in the A356 alloy (Al-7Si), and the effect of the Gr particles on the mechanical and tribological properties was investigated. In spite of this, the input process parameters for the dry sliding wear test at room temperature against the EN31 steel disc were optimised through ANOVA analysis. The fabricated A359—X wt% (X = 0, 2.5, 5, 7.5) composite through bottom pouring stir casting techniques was analysed microstructurally by using XRD and FESEM analysis. The micro Brinell hardness and tensile strength were investigated per ASTME10 and ASTME8M standards. A wear test was performed for the composite pins against the EN31 steel disc according to ASTM G99 specifications. The XRD analysis results depict the presence of carbon (C), aluminium (Al), and silicon (Si) in all the wt% of the Gr reinforcement. However, along with the elements, the Al₂Mg peak was confirmed for the A356—7.5 wt% Gr composite and the corresponding cluster element was confirmed in FESEM analysis. The maximum micro Brinell hardness of 92 BHN and U.T.S of 123 MPa and % elongation of 7.11 was attained at 5 wt% Gr reinforcement due to uniform Gr dispersion in the A356 alloy. Based on the ANOVA analysis, the optimal process parameters were obtained at 20 N applied load, 1 m/s sliding velocity, and 1000 m sliding distance for the optimal wear rate of 0.0052386 g/km and 0.364 COF. Full article

The dry sliding wear behavior of as-cast pristine and boron-modified Ti-6Al-4V (Ti64) alloys (having 0.3 and 0.55 wt% B) is investigated using pin-on-disc experiments with the pin being Ti64 alloy and the EN31 steel disc. Experiments are performed at sliding speeds (s) of 1, 2, and 4 m/s and temperatures 300 and 573 K. A mixed response in wear behavior is observed. At the lowest sliding speed, all three alloys (except 0.55B alloy at 300 K) exhibit similar wear rates, with abrasive wear being the dominant wear mechanism. At 2 m/s, temperature and s increase, and adhesive wear takes over along with delamination wear. Here, the 0.55B sample shows the highest wear rate due to the debonding of more TiB particles, which increases three body abrasion wear. With further increase in s to 4 m/s, delamination and oxidation wear are observed for all the samples. XRD evaluation shows traces of TiO₂ and Fe₂O₃, which imply the formation of MML in samples tested at s = 4 m/s, which is also validated through subsurface microstructure analysis. It is found that MML having more TiB particles has more stability, because of which 0.3B samples show higher wear rate. Full article

The purpose of the following study was to compare the effect of the shape of a tool on the joint and to obtain the values of Friction Stir Welding (FSW) parameters that provide the best possible joint quality. The material used was an aluminium alloy, EN AW-3004 (AlMn1Mg1). To the authors’ best knowledge, no investigations of this alloy during FSW have been presented earlier. Five butt joints were made with a self-developed, cylindrical, and tapered threaded tool with a rotational speed of 475 rpm. In order to compare the welding parameters, two more joints with a rotational speed of 475 rpm and seven joints with a welding speed of 300 mm/min with the use of a cylindrical threaded pin were performed. This involved a visual inspection as well as a tensile strength test of the welded joints. It was observed that the value of the material outflow for the joints made with the cylindrical threaded pin was higher than it was for the joints made with the tapered threaded pin. However, welding defects in the form of voids appeared in the joints made with the tapered threaded tool. The use of the cylindrical tool resulted in higher values for about 37% of mechanical properties compared with the highest result for the tapered threaded joint. As far as the parameters were concerned, it was concluded that most of the specimens were properly joined for a rotational speed of 475 rpm. In the joints made with a welding speed of 300 mm/min, the material was not stirred properly. The best joint quality was given for a rotational speed of 475 rpm as well as a variety of welding speed values between 150 and 475 mm/min. Full article

The main objective of this study was to determine the chemical composition of essential oils (EOs) obtained from leaf, old branches, and young branches of a coniferous species Calocedrus decurrens acclimated to Corsica. The analytical investigation was conducted by GC(RI), GC-MS, pc-GC, and NMR. C. decurrens leaf, old branches, and young branches EOs contained α-pinene (11.2; 56.6; 22.3%), myrcene (13.4; 8.4; 9.7%), Δ-3-carene (31.3; 5.2; 11.1%), limonene (6.4; 5.1; 5.5%), terpinolene (6.9; 1.5; 3.2%), and pin-2-en-8-ol (4.2; 4.5; 10.4%) as major components, respectively. Special attention was paid to purifying and identifying four unusual pinane derivatives: pin-2-en-8-ol, pin-2-en-8-yl Acetate, pin-2-en-8-al, and methyl pin-2-en-8-oate. The last two are reported for the first time. Full article