Investigating the Tribological Characteristics of Burnished Polyoxymethylene—ANFIS and FE Modeling

ABSTRACT

Polymers are utilized in numerous tribological applications because of their excellent characteristics; for example, accommodating shock loading and shaft misalignment. A high surface finish is required to ensure consistently good performance and extended service life of manufactured polymeric components. Burnishing is the best choice as a finishing process for this study due to its ability to increase hardness, fatigue strength, and wear resistance and also introduce compressive residual stress on the burnished workpiece. Due to the complexity and uncertainty of the machining processes, soft computing techniques are preferred for anticipating the performance of the machining processes. In this study, ANFIS as an adaptive neuro-fuzzy inference system was applied to anticipate the workpiece hardness and surface roughness after the roller burnishing process. Five burnishing variables, including burnishing depth, feed rate, speed, roller width, and lubrication mode, were analyzed. A Gauss membership function was used for the training process in this study. The predicted surface roughness and hardness data were compared with experimental results and indicated that the Gauss membership function in ANFIS has satisfying accuracy as high as 97% for surface roughness and 96% for hardness. Furthermore, the generated compressive residual stress on the burnished surface was studied by a 2D finite element model (FEM). The simulated results of residual stress were validated with the experimental results obtained from X-ray diffraction (XRD) tests.     

Evaluation of Heat Treatment Effect on the Tensile Strength of Mild Steel Welded Joints Using Ultrasonic Testing

Russian Journal of Nondestructive Testing - The tensile strength of welded joints subjected to thermal stresses degrades with age. Tensile strength is generally assessed using tensile test, which...     

The heating effect of iron-cobalt magnetic nanofluids in an alternating magnetic field: application in magnetic hyperthermia treatment

In this research, FeCo alloy magnetic nanofluids were prepared by reducing iron(III) chloride hexahydrate and cobalt(II) sulfate heptahydrate with sodium borohydride in a water/CTAB/hexanol reverse micelle system for application in magnetic hyperthermia treatment. X-ray diffraction, electron microscopy, selected area electron diffraction, and energy-dispersive analysis indicate the formation of bcc-structured iron-cobalt alloy. Magnetic property assessment of nanoparticles reveals that some samples are single-domain superparamagnetic, while others are single- or multi-domain ferromagnetic. The stability of the magnetic fluids was achieved by using a CTAB/1-butanol surfactant bilayer. Results of Gouy magnetic susceptibility balance experiments indicate good stability of FeCo nanoparticles even after dilution. The inductive properties of corresponding magnetic fluids including temperature rise and specific absorption rate were determined. Results show that with increasing of the nanoparticle size in the single-domain size regime, the generated heat increases, indicating the significant effect of the hysteresis loss. Finally, the central parameter controlling the specific absorption rate of nanoparticles was introduced, the experimental results were compared with those of the Stoner-Wohlfarth model and linear response theory, and the best sample for magnetic hyperthermia treatment was specified.     

Catalytic and Photopolymerization of Isoprene

Stereoregularity of photopolymerized isoprene was determined by NMR spectroscopy and compared with the stereoregularity of polyisoprene which was prepared using n-butyllithium catalyst. It was found that photopolymerization of isoprene gave a high percentage of trans-1,4, while the n-Buli catalyst gave a high percentage of cis-1,4 structure.     

Binder addition methods and binder distribution in high shear and fluidised bed granulation

Fluidised beds and high shear mixers are both important in industrial granulation. The binder addition method (pouring, melt-in, spraying) affects the growth and properties of granules and is therefore of vital importance to the fundamental understanding of this detailed process. Non-uniformity of binder distribution is well known in high shear melt granulation, however, there is limited literature surrounding binder distribution in fluidised bed granulation. It was therefore the aim of the paper to compare the binder distribution using alternative addition methods in both high shear mixer and fluidised bed.In this work two binder addition methods, ‘wet’ and ‘dry’, in a fluidised bed and high hear mixer were used to successfully produce granules with a typical pharmaceutical size, 150-300 μm. The granules were analysed for final binder distribution in different size classes using Patent V blue dye and ultra-violet spectrometry.All binder addition methods supported previous work showing non-uniformity of binder distribution throughout the size classes. High shear mixer results show great similarity in binder content whichever binder addition method was chosen. This is likely to be due to the same mechanisms occurring due to the impeller forces in the process, mean while the fluidised bed results show little similarity. The binder distribution by mass is also investigated and shows that although most studies show a relative higher binder content in the larger size classes that actually the majority of binder can instead be found around the mean size of the batch.     

Catalytic coprocessing of coal and petroleum residues with waste plastics to produce transportation fuels

Coprocessing reactions with waste plastics, petroleum residues and coal were performed to determine the individual and blended behavior of these materials using lower pressure and cheaper catalysts. The plastic used in this study was polypropylene. The thermodegradative behavior of polypropylene (PP) and PP/petroleum residues/coal blends were investigated in the presence of solid hydrocracking (HC) catalysts. A comparison among various catalysts has been performed on the basis of observed temperatures. The higher temperatures of initial weight loss of PP shifted to lower values by the addition of petroleum residues and coal. The catalysts were also tested in a fixed-bed micro reactor for the pyrolysis of polypropylene, petroleum residues and coal, alone and blended together in nitrogen and hydrogen atmosphere. High yields of liquid fuels in the boiling range 100-480 °C and gases were obtained along with a small amount of heavy oils and insoluble material such as gums and coke. The results obtained on the coprocessing of polypropylene with coal and petroleum residues are very encouraging as this method appears to be quite feasible to convert plastic materials into liquefied coal products and to upgrade the petroleum residues and waste plastics.     

Strong carbon nanofibers from electrospun polyacrylonitrile

Strong carbon nanofibers with diameters between 150 nm and 500 nm and lengths of the order of centimeters were realized from electrospun polyacrylonitrile (PAN). Their tensile strength reached a maximum at 1400 °C carbonization temperature, while the elastic modulus increased monotonically until 1700 °C. For most carbonization temperatures, both properties increased with reduced nanofiber diameter. The tensile strength and the elastic modulus, measured from individual nanofibers carbonized at 1400 °C, averaged 3.5 ± 0.6 GPa and 172 ± 40 GPa, respectively, while some nanofibers reached 2% ultimate strain and strengths over 4.5 GPa. The average tensile strength and elastic modulus of carbon nanofibers produced at 1400 °C were six and three times higher than in previous reports, respectively. These high mechanical property values were achieved for optimum electrospinning parameters yielding strong PAN nanofibers, and optimum stabilization and carbonization temperatures, which resulted in smooth carbon nanofiber surfaces and homogeneous nanofiber cross-sections, as opposed to a previously reported core–shell structure. Turbostratic carbon crystallites with average thickness increasing from 3 to 8 layers between 800 °C and 1700 °C improved the elastic modulus and the tensile strength but their large size, discontinuous form, and random orientation reduced the tensile strength at carbonization temperatures higher than 1400 °C.     

Prediction of the self-diffusion coefficients in aqueous KCl solution using molecular dynamics: A comparative study of two force fields

Molecular dynamic simulation was used to calculate the self-diffusion coefficients of ions in aqueous KCl solution. The simulations were performed for enough time (12 ns) in the form of all-atom to determine the accurate values of the self-diffusion coefficients. The values of the self-diffusion coefficients were calculated by Einstein equation. Two different force fields of Dang and Deublein were employed in the simulations, and we found that at low ion concentration (equal or less than 3mol/(kg of H₂O)), the Dang force field is more accurate for prediction of the selfdiffusion coefficient of K⁺ ions and Deublein force field is more accurate for Cl^? ions. An Arrhenius type equation was used to model the temperature dependence of the self-diffusion coefficients and the diffusion activation energies at different ion concentrations were reported.     

Synthesis and characterization of novel Pr6O11/Mn3O4 nanocomposites for electrochemical supercapacitors

This study presents the successful synthesis of praseodymium oxide, Pr₆O₁₁ and hausmannite manganese oxide, Mn₃O₄ nanoparticles, along with a novel synthesis of (Pr₆O₁₁/Mn₃O₄) nanocomposites by employing the hydrothermal route followed by post thermal annealing. X-ray Diffraction, Field Emission Scanning Electron Microscopy and Energy Dispersive X-ray characterization techniques are being adapted to analyze the physical characteristics of all the synthesized materials. XRD results reveal the crystalline nature of the synthesized materials. FE-SEM results display the irregular nanograins of Mn₃O₄ and a regular network of interconnected Pr₆O₁₁ nanoparticles. Nitrogen adsorption/desorption tests confirm the mesoporous nature of all the synthesized electrode materials. The Pr₆O₁₁/Mn₃O₄ ??2 electrode material exhibits an outstanding specific capacitance of 794.58?F/g at a current density of 0.5?A/g, as compared to the 521.24?F/g for the Pr₆O₁₁ electrode material. These investigations provide an easy and efficient method to develop nanocomposites (Pr₆O₁₁/Mn₃O₄) with better electrochemical characteristics, as electrode materials for supercapacitor applications.     

In vitro bioactivity of glass–ceramics of the CaMgSi2O6–CaSiO3–Ca5(PO4)3F–Na2SiO3 system with TiO2 or ZnO additives

Glass–ceramic materials based on diopside [CaMgSi₂O₆]–wollastonite [CaSiO₃]–fluoroapatite [Ca₅(PO₄)₃F]–sodium silicate [Na₂SiO₃] system with TiO₂ or ZnO additives were successfully prepared and examined in vitro, by using a simulated body fluid (SBF) solution, to be suitable for restorative dental and bone implant materials. In vitro bioactivity of the glass–ceramics was examined by using scanning electron microscopy equipped with energy dispersive X-ray detectors (EDAX–SEM) and inductive coupled plasma emission spectroscopy (ICP).