| High-performance aviation composite materials have been widely used in the load-carrying and non-load-carrying structures in modern aircraft. The primer coatings on the composite surface structures of civil aircraft must be able to perform excellent comprehensive properties. Serialization and industrialization of these coating materials have been realized in many developed countries. However, China still belongs to a less developed country in this field. To solve the problems in preparation of the primer coating materials and the comprehensive characterization of the coating, a systemic research by this paper has been developed. A new thought was put forward to introduce the environmental friendly nano-sized Ti additive to prepare the modified coating material and to form the high-performance modified primer coating. The main research contents and results including that:The material preparation theory was formulated which plans to modify the traditional aerial primer by nano-sized Ti particle additives with silane coupling treatment and pre-coated polymer layer. The coupling treatment of nano-sized Ti powder was carried out with KH-560silane as the coupling agent. The nano-sized Ti/PAM (nano-sized Ti/polyacrylamide) composite particles were prepared by an in-situ polymerization process with sodium dodecyl benzene sulfonate (SDBS) as the dispersant. The powder samples were characterized by XPS, TEM and FTIR techniques, respectively. The effect of coupling treatment and polymerization process on the dispersibility of the particles in M03epoxy resin dilution was studied as well. It was found that the nano-sized Ti/PAM composite particles have a core-shell structure. The agglomeration among the particles was slight, and the hydrophobic property of the particles was increase. In addition, the nano-sized Ti/PAM composite particles can be well-dispersed in the dilution of M03epoxy resin. The initial sedimentation of the nano-sized Ti/PAM composite particles in the dilution can be visually inspected after20h, and the dispersed state of the powder is pretty stable.The treatment details of the particle additives and the compositing of the particle additives with the traditional aircraft epoxy primer binders have also been studied by experiment. The technological parameters during compositing were optimized in accordance with the actual performance requirements in civil aviation. The specific functional requirements and the realization approach for modified primer with nano-sized Ti particle additives have been studied. The specific type of the nano-sized Ti powder has been selected as well. The effect of technological parameters on the scrubbing property of the modified primer has been investigated. The optimum adding amount of the nano-sized Ti powder was obtained.The20P20-3polyurethane modified epoxy primer for composite surfaces in civil aircraft made by Akzo Nobel company was selected as the basic primer material. Special nano-sized Ti powder additives and other chemicals were adopted to form the modified primer material. Some comprehensive application properties such as remarkably electromagnetic wave shielding, high coating strength, and enhancing of radar wave signals can thus be archieved by the treatment details of the particle additives and the composite modification technology with the nano-sized particle. All of those works have provided theory basis for the development of the domestic high performance aircraft primer coating on the composite surfaces in civil aircraft.Modern material characterization methods were adopted to set up the basic property data sheet for the high-performance coatings on the composite surfaces in civil aircraft. The impact strength and tensile strength of the cured modified primer samples with different nano-sized Ti powder adding amount were studied by experiment. The coating strength of the modified primer material with different nano-sized Ti powder adding amount were also characterized. The effects of the modified epoxy primer on the electromagnetic shielding effectiveness of the typical GFEP (Glass Fiber Enhanced Polymer, GFEP) fuselage structure samples have been studied, In addition, the corrosion mechanism of the coating, the principle of electromagnetic shielding and the electromagnetic effectiveness of the coating have been discussed as well. It is found that the samples with modified primer perform good electromagnetic shielding properties with the electromagnetic shielding effectiveness values of about9.5dB to29.7dB when the frequency of the coming electromagnetic waves ranges from300kHz to1.5GHz. The dispersion condition of nano-sized particle which was obtained by variable speed stirrer and ultrasonic assisted dispersion is obviously better than that obtained only by the sanding dispersion process. Painting process of nano-sized Ti powder modified primer has been researched and optimized. The influence of temperature on the viscosity of the coating material has been investigated. The effects of painting parameters such as mixing process, filtering details, painting pressure etc on the coating quality of the nano-sized Ti modified coatings have been studied. The operation process and technology details of painting on the composite surface in civil aircraft have been discussed. According to the discussion, the painting parameters were optimized. Therefore, guidance documents of painting which suits the actual operation process on the composite surface in civil aircraft have been developed.The comprehensive properties of the nano-sized Ti powder modified primer coating material have been studied. On the basis of preparation of high performance composite primer, the comprehensive properties of the modified primer coating material such as protection, adhesion, durability, compatibility, environmental friendly etc have been characterized according to the special operating environment of civil aircraft. The primer coating which is suitable for the application on the composite surfaces in civil aircraft was finally obtained by optimization. The performance system of the nano-sized modified primer coating has been established basically. At the same time, the test methods and essential parameters of the coating properties of the modified primer coating material have been established. |
PDF Full Text Request