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Investigation of nanomechanical and adhesion behavior for AlN coating and AlN/Fe2-3N composite coatings created by Active Screen Plasma Nitriding on Al 1050
摘要： This study investigated the effect of nitriding time and temperature on the mechanical properties of the composite AlN/Fe2-3N coating deposited on the pure aluminium substrate using the novel Active Screen Plasma Nitriding (ASPN) method. ASPN treatment was performed for 2, 5, 10, 15 h at temperatures of 450,500, and 550 (cid:1)C and Conventional Plasma Nitriding (CPN) treatment was carried out for 5 h at 500 (cid:1)C. All treatments were performed at the 10 KHz frequency with 80% duty cycle on the Al1050 substrate under 20%H2t80%N2 atmosphere. Phase and microstructure studies were performed using, respectively, the grazing incidence x-ray diffraction (GIXRD) system and the ?eld emission - scanning electron microscopy (FE-SEM) system equipped with energy-dispersive spectroscopy (EDS) analyzer. The mechanical strength of the coating was evaluated by the roughness, nano-hardness, nano-scratch, and adhesion strength tests performed on coated and uncoated specimens. According to the results, the uncoated Al1050 specimen, the CPN-treated specimen, and the ASPN-treated specimen had a mean nano-hardness of 0.7 ± 0.1 GPa, 10.9 ± 0.6 GPa, and 9.6 ± 0.5 GPa, respectively. It was also found that the single-phase AlN coating has a better adhesion strength and scratch strength (LC3 ? 12 N) than the composite AlN/Fe2-3N coating (LC3 ? 10 N). Examination of scratch mechanisms in hard AlN and AlN t Fe2-3N coatings deposited on a soft aluminium substrate showed that the failures in these coatings are due to tensile-type Hertzian cracks. However, as the load increases, the substrate undergoes increasing deformation and failures shift to chipping and interfacial spallation.
关键词： Adhesion strength,Active screen plasma nitriding,Pure aluminium,Conventional plasma nitriding,Scratch resistance,Nanoindentation
更新于2025-09-23 15:23:52
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Comparison of the Physicochemical Properties of TiO2 Thin Films Obtained by Magnetron Sputtering with Continuous and Pulsed Gas Flow
摘要： In this paper, a comparison of TiO2 thin ?lms prepared by magnetron sputtering with a continuous and pulsed gas ?ow was presented. Structural, surface, optical, and mechanical properties of deposited titanium dioxide coatings were analyzed with the use of a wide range of measurement techniques. It was found that thin ?lms deposited with a gas impulse had a nanocrystalline rutile structure instead of ?brous-like anatase obtained with a continuous gas ?ow. TiO2 thin ?lms deposited with both techniques were transparent in the visible wavelength range, however, a much higher refractive index and packing density were observed for coatings deposited by the pulsed gas technique. The application of a gas impulse improved the hardness and scratch resistance of the prepared TiO2 thin ?lms.
关键词： optical properties,scratch resistance,thin ?lms,gas impulse magnetron sputtering,microstructure,hardness,surface properties,mechanical properties,TiO2
更新于2025-09-23 15:21:21
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Recovery of scratch deformation formed on crosslinked polyorganosiloxane films
摘要： As consumers generally desire longer lasting scratch-free coatings, scratch resistance has become one of the most important properties of automotive coatings. Surface scratches that deform a coating but do not break it can recover over time, eventually even becoming invisible to the human eye. This phenomenon arises from elastic-plastic behavior and is called "self-recovery". This paper mainly focuses on the recovery of scratch deformations. Conventional coatings with low glass transition temperature (Tg) have fast recovery characteristics, like rubbers, but cannot attain sufficient hardness. Therefore, it is difficult to simultaneously improve both scratch recovery characteristics and hardness in conventional coatings such as 2 K urethane coatings consisting of acrylic polyols because both arise from the same causes as the mobility of the main chain of the coating. Herein, we explore the remarkable improvement of scratch recovery characteristics without sacrificing hardness by using a base resin with a siloxane main chain instead of a carbon-carbon main chain such as that of an acrylic polyol. We demonstrate that crosslinked polyorganosilsesquioxane coatings (Si-films) achieve both hardness suitable for automobile coatings and improved scratch recovery characteristics superior to those of conventional coatings (C-films). Si-films demonstrated 20% better elastic recovery index than C-films, and the Si-films recovered about twice as fast as the C-films. Scratch deformations on the Si-films almost disappeared after 15 min, even at room temperature, while C-films were needed over 24 days. Thus, coatings based on a siloxane main chain may offer dramatically improved self-recovery.
关键词： Scratch resistance,Coatings,Scratch deformation,Recovery,Polyorganosiloxane,Automotive
更新于2025-09-10 09:29:36
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Investigation of reinforced performance of modified graphene oxide/high solid content polysiloxane nanocomposite coating films
摘要： Graphene oxide was modi?ed using long-chain silicone. The modi?ed graphene oxide (MGO) was obtained with a broader spacing of layers (1.45 nm) which means more bene?cial to polysiloxane entering into the laminates of MGO sheets. Then, MGO sheets were combined with polysiloxane which synthesized without any organic solvent to prepare nanocomposite coatings via cross-linking curing reaction. The solid content of polysiloxane can be reached up to 86%. Due to strong interfacial interaction and synergistic reinforcing between MGO sheets and polysiloxane, when blended with 1.00 wt% of MGO, the micro-hardness and elastic modulus of coating ?lms were increased by 57% and 24% comparing with pure polysiloxane coating ?lm, respectively. Subsequently, a 48% improvement of macro-scratch resistance can be achieved. Simultaneously, MGO/polysiloxane coating ?lm showed excellent wear resistance due to the unique two-dimensional geometry and low frictional coef?cient of MGO sheets at work in homogeneous dispersion system.
关键词： Polysiloxane,Scratch resistance,Wear resistance,Nanocomposite coatings,Graphene oxide
更新于2025-09-09 09:28:46