Key Engineering Materials Vol. 871

Abstract: Composite material is widely used to maintain damaged structures of aircraft. The 3D finite element model of composite cement maintenance for aircraft is established by finite element method software ANSYS Workbench. The structural characteristics and usage status of the composite cement maintenance model is analyzed, and then the optimal structural parameters of the composite patch are obtained, including the length, width and thickness. The results show that the composite cement maintenance method could effectively restore the rigidity, and improve the strength of the structure. Furthermore, the optimal design for composite patch ensures safety of aircraft, economics of maintenance, and operability of repair methods.

Abstract: This paper briefly describes the relevant properties of epoxy resin materials, and introduces the domestic and international progress of dicyclopentadiene (DCPD) phenolic epoxy resin. The process conditions of dicyclopentadiene phenol resin and epoxy resin were studied. Dicyclopentadiene phenol epoxy resin with different degrees of polymerization was prepared. The reaction heat was measured and the curing temperature, time and curing were analysed. The influence of factors such as the agent structure on the gel time and curing degree of DCPD phenol epoxy resin; the effects of temperature and time on the curing reaction of DCPD phenol epoxy resin were discussed.

Abstract: This study is to explore the changes in the performance of sports equipment under the action of carbon fiber reinforced epoxy composites. This paper studies the effects of carbon fiber reinforced epoxy composites in pole vault, bicycle, and tennis. The research results show that the performance of sports equipment based on carbon fiber reinforced epoxy composite materials has been greatly improved, with outstanding effects in terms of thermal properties, interface properties, mechanical properties, and fatigue resistance. Carbon fiber reinforced epoxy composite material damage expansion is divided into five stages: matrix cracking, interfacial degumming, delamination, fiber fracture, fracture. Therefore, carbon fiber reinforced epoxy composite materials are comprehensive for the improvement of sports equipment, which has greatly promoted the further development of sports. Carbon fiber reinforced epoxy composite materials can be promoted in other fields, thereby obtaining greater progress with help of high technology. The study of carbon fiber reinforced epoxy composites in this paper has a positive effect on subsequent research.

Abstract: The study aims to explore the preparation of aviation mechanical carbon fiber reinforced plastics (CFRP) and the properties of CFRP composites. Taking the aero box body as an example, the mechanical properties of CFRP are studied. The preparation of CFRP is analyzed by searching the data. CFRP plates are explored according to the stress analysis of composite materials. The finite element analysis software ANSYS Workbench and UG software are adopted to build the 3D model of the aero box body. After adding materials in ANSYS Workbench and simplifying the UG model, the finite element analysis of the model is carried out by computer. The 3D model of the aero box is constructed, the finite element analysis of the aero box is carried out, and the mechanical properties of CFRP are explored. In this study, the possibility of the practical application of CFRP in the aviation box body lightweight is clarified, which gives a direction for the subsequent actual molding and guides the application of CFRP in aviation field.

Abstract: The ProENGINEER software is used to build a geometric model for the whole process cavity and internal structure and conduct the internal dynamic simulation of cavity with different diffusion temperatures of 1,000°C, 1,050°C, 1,100°C and 1,150°C, and different diffusion time of 5 min, 10 min, 15 min and 20 min. Analyze the process control indexes by combining with specific thermal diffusion test, and study the relationship between hydrodynamic parameters and diffusion uniformity, Comprehensively investigate the effects of the diffusion temperature and diffusion time on doping, achieving the requirements of impurity distribution in materials.

Abstract: Retracted papers: One of the major features of conjugated polymer is the rigid molecular conformation which is absolutely different with that of flexible polymer. In this study, the non-conjugated aggregate structure of conjugated polymers was explored for the first time by using Small Angle X-ray Scattering (SAXS). It is found that there is a large-scale non-conjugated packing structure inside the Poly (3-alkylthiophene) (P3AT), which can be attributed to loose stacked structure of rigid conjugated main chain in P3AT. Thus, a large number of pore structures with the porosity of about 10^-4 to 10^-3 are formed, and such pore structures exhibit the characteristics of a mass fractal structure.

Abstract: The first-principles calculations by CASTEP program based on the density functional theory is applied to calculate the cohesive energy, enthalpy of formation, elastic constant, density of states and Mulliken population of Ag₃Sn、AgZn₃ and Ag₅Zn₈. Furthermore, the elastic properties, bonding characteristics, and intrinsic connections of different phases are investigated. The results show that Ag₃Sn、AgZn₃ and Ag₅Zn₈ have stability structural, plasticity characteristics and different degrees of elastic anisotropy; Ag₃Sn is the most stable structural, has the strongest alloying ability and the best plasticity. AgZn₃ is the most unstable structure, has the worst plasticity; The strength of Ag₅Zn₈ is strongest, AgZn₃ has the weakest strength, the largest shear resistance, and the highest hardness. Ag₅Zn₈ has the maximum Anisotropy index and Ag₃Sn has the minimum Anisotropy index. Ag₃Sn、AgZn₃ and Ag₅Zn₈ are all have covalent bonds and ionic bonds, the ionic bonds decrease in the order Ag₃Sn>Ag₅Zn₈>AgZn₃ and covalent bonds decreases in the order Ag₅Zn₈>Ag₃Sn>AgZn₃.

Abstract: Polyimide/Al₂O₃ films were prepared by the surface modification with different hydrolysis time, ion exchange technique and heat treatment using polyimide films as the substrates and aluminum chloride as the precursor of Al₂O₃. The morphology, thermal properties and electrical properties of the composite films were characterized and tested. The results indicated the alumina distributed in certain thickness on the surface of the films and there was a clear interface layer between the alumina layer and the substrate. The breakdown strength of the composite films maintains the excellent properties of the pristine film while the thermal and corona-resistant time properties of composite films were better than the pristine film due to introducing aluminum oxide. The composite film which used KOH to treat for 90 min has the longest corona-resistant time (101.2 min), which was almost 10 times longer than the pristine film.

Abstract: With the widespread use of film transistors, amorphous oxide thin films have excellent transparency and conductivity, stable performance, smooth and smooth surface, easy to etch and large-area preparation, are compatible with existing processes, and do not require subsequent annealing to simplify the process. Process and other advantages have been applied to many fields such as thin film transistors. The principle of the amorphous oxide is basically the same as that of the crystalline state, Magnetron sputtering technology can prepare super-hard films, corrosion-resistant friction films, superconducting films, magnetic films, optical films, and various films with special functions. It is widely used in the field of industrial film preparation. This article focuses on the principle and characteristics of magnetron sputtering technology for electronic materials, the development history of magnetron sputtering technology and its development trend.

Abstract: A picosecond laser in spin-cutting mode was used to drill 500μm diameter microholes on 150μm thick aluminium nitride ceramic. The effects of laser processing parameters such as the laser power, scanning speed, and defocus amount on the microhole quality were studied. The results show that as the laser power increases, the inlet and outlet diameters of the holes increase, the taper decreases slightly, and the thickness of the recast layer decreases evidently. The scanning speed has no obvious effect on the diameter and taper of the hole; however, the hole can not be drilled through when the speed is too large. Positive defocus can effectively reduce the taper of the hole. Under 28.5W laser power, 400Hz frequency, 200mm/s scanning speed, and zero defocus amount conditions, high-quality microholes with a taper of 0.85° were obtained.