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Abstract Introduction: The thermal spraying method with the aim of increasing the working life of steel parts is one of the most important solutions in surface engineering to solve the problem of wear. Methods In this research, NiCrBSi and NiCrBSi-MoS2 coatings were applied on 304 stainless steel by thermal spraying, and then the wear behavior was evaluated at ambient temperature and 500 degrees. Phase investigations were done by X-ray diffraction test. The chemical composition of the coatings was checked with the help of energy dispersive spectrometer analysis. Porosity was investigated with the help of optical microscope and scanning electron microscope images. The hardness of the samples was measured using a microhardness test. In order to check the adhesion and tribological behavior of the coatings, VDI3198 and ASTM-G99 pin-on-disk tests were used, respectively, and finally, the wear mechanism was evaluated using SEM images and EDS analysis of the wear surfaces of the samples. Findings: Phase analysis (XRD) and chemical composition (EDS) showed that the coating has an amorphous and crystalline phase and the most important phases of the coating are nickel-gamma, carbide and boride. Porosity measurement results with the help of image analysis software showed higher porosity of NiCrBSi-MoS2 coating. The results of hardness measurement from the cross-section of the samples indicated an increase in the hardness of the substrate in the presence of coatings, and the addition of MoS2 particles decreased the hardness of the NiCrBSi coating. The coating with MoS2 has better adhesive behavior due to its crystalline structure and better plastic deformation ability. The tribological results indicated the superiority of the NiCrBSi-MoS2 coating due to the appropriate ability of plastic deformation as well as the intrinsic lubrication property (based on the crystal structure) in this test. It was found that at ambient temperature, the samples mainly had lamellar wear mechanism, and at high temperature, oxidation wear as a secondary mechanism helped to destroy the surface. Conclusion: The addition of MoS2 to NiCrBSi coating caused more porosity, more roughness, less hardness and better wear behavior of the coating. The addition of MoS2 to the coating improved the wear resistance of the coating at high temperature.

AbstractIntroduction: Electrolytic plasma oxidation coatings are one of the most important materials used to deal with the wear of aluminum parts due to their compact, sticky and hard nature. In recent years, improving the surface properties of these coatings with the help of adding reinforcement particles has attracted the attention of researchersMethods In this study, plasma electrolytic oxidation (PEO) process was applied in two modes, normal and composite, to coat aluminum 7075. To produce the composite coating, the same electrolyte as the normal mode was used with the addition of 12 grams per liter of silicon oxide particles. Characterization of coatings was done with the help of SEM, X-ray diffraction analysis, energy dispersive spectrometer (EDS) analysis, roughness measurement and hardness measurement. The tribological behavior of coatings was investigated with the help of pin-on-disk test and the analysis of the wear mechanism of the samples was done with the help of SEM images and EDS analysis of wear surfaces.Findings: Both coatings had a pancake structure with craters. Also, the drainage channels that lead to the porosity of the coatings were less created on the surface of the composite coating. The normal coating was an oxide coating with an amorphous/crystalline nature, but the composite coating had silicon oxide and mullite crystalline phases in addition to these two phases. The lowest weight loss (highest wear resistance) and friction coefficient were obtained for the composite coating. wear mechanism was also observed delamination wear and oxidation wear for substrate, abrasion, adhesive and oxidation wear for PEO coating, and fine scratch mechanisms and adhesive mechanism with very little effect for composite coating.

Background and Objective: N-methylpyrrolidine is a highly potent solvent with toxic and adverse ecological properties that has historically been widely used in the chemical and petrochemical industries. Due to the health and safety، toxicity and environmental effects of effluents containing NMP، these effluents should be pre-treated before biological treatment methods. The aim of this study was to remove N-methylpyrrolidone by photo- Fenton process. Materials and Methods: For testing, solutions such as sulfuric acid, iron sulfate 7, oxygenated water, sodium hydroxide and distilled water were added to N-methypyrrolidine compounds in the reactor. Then, the removal process was investigated in two stages: complete mixing and adding solutions. Results: The results revealed that the Fenton process cannot be used successfully to treat the hypothetical refinery effluent containing NMP. However، the photo-phanton process mineralized and degraded the NMP composition. Increase in 30% H2O2 concentration to the optimal dose of 1 mL led to the highest degradation (94%) and decrease in COD level of solution (42.1%). Conclusion: It can be concluded that advanced oxidation by photo-phanton reaction can be a promising advanced oxidation technology for decomposition and pre-treatment of NMP-containing wastewaters for further biological treatment.

The atomic nucleus is a complex many-body system that consists of two types of fermion (neutron and proton). They are in the strong interaction. The statistical properties of energy levels and influence of strong force between these fermions are well described by random matrix theory. Resonance of energy levels depends on the Hamiltonian symmetry placed in one of the GOE, GUE and GSE ensembles or in the integrable system in a Poissonian ensemble. We can study resonance of energy levels of one system with eigenvalues of the Hamiltonian. This paper by using the nuclear shell model investigate the influence of strong force on the nuclear structure in Calcium and Titanium isotopes with quantum chaos theory. Difference between these isotopes is in their Valance particles. Investigation the energy levels of them is show that behavior of the nuclear system in Ti48 is very close to GOE ensemble but in Ca48 is a little bit far from this behavior

Stability analysis of the nuclear structure as a many-body system has a particular importance in nuclear physics. ‎Understanding its statistical properties and also phase transitions provide useful information about nuclear structure and nuclear processes. The statistical properties of the set of energy levels of a system are well described by random matrix theory in quantum chaos. Resonance of energy levels depends on the Hamiltonian symmetry that placed in one of the GOE, GUE, GSE ensembles and in the integrable system in the Poissonian ensemble. The statistical analysis of energy levels by random matrix theory will be possible by calculating the Hamiltonian’s eigenvalues of the system. The calcium chain is an ideal test bench for study on the nuclear structure due to its existing double magic isotopes. In the present work, we use quantum chaos theory in order to investigate the stability of the nuclear structure of 50Caand 48Ca isotopes, and the results obtained are compared with those of the Isolde-Cern laboratory.