Aerosol Deposition Method (Adm) For Nano-Crystal Ceramics Coating Without Firing
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AEROSOL DEPOSITION METHOD (ADM) FOR NANO-CRYSTAL CERAMICS COATING WITHOUT FIRING Jun Akedo, Maxim Lebedev, Atsushi Iwata, Hisato Ogiso and Shizuka Nakano National Institute of Advanced Industrial Science and Technology, Namiki 1-2-1 Tsukuba Ibaraki, 305-8564 Japan ABSTRACT Aerosol deposition method (ADM) for shock-consolidation of fine ceramics powder to form dense and hard layers is reported. Submicron ceramic particles were accelerated by gas flow in the nozzle up to velocity of several hundred m/s. During interaction with substrate, these particles formed thick (10 ~ 100 µm), dense, uniform and hard ceramics layers. Experiments were fulfilled at room temperature. The results of fabrications, microstructure and mechanical properties of oxides (Al2O3; (Ni,Zn)Fe2O3; Pb(Zr0.52,Ti0.48)O3 and non-oxide (AlN; MgB2) materials are presented. Every layer has polycrystalline structure with nano-meter order scale. INTRODUCTION Several deposition methods based on the principle of particle impaction have already been investigated. This family of methods includes depositing ultrafine particles via electrical field acceleration (Electrostatic Particle-Impact Deposition (EPID) [1], or via acceleration by mixing with high-speed gas flow (Gas Deposition Method (GDM) [2,3]. For two-dimensional pattern formation of the metal, Cold Spray Method (CSM) [4] and Hypersonic Plasma Particle Deposition (HPPD) [5] for Si, SiC, ceramics coating are used. Fundamentally, these methods are based on particle jet with or without thermal or plasma energy assistance. EPID is appropriate only to conductive material, for example metals or carbon, due to necessity of charging up the particles. Thick layer formation (over 1 µm) in EPID has not been reported. GDM is applicable to metal and ceramic material using ultrafine particles, which have diameter under 100 nm and has a highly activated surface. In CSM large size particles with diameter over 10 µm are accelerated by hot gas. CSM is similar to conventional thermal spray coating, but for ceramics materials this coating has not been successful. In HPPD active ultrafine particles are used. These particles are produced under the high pressure after condensation from the gas phase in the nozzle. Deposition efficiency of EPID seems very low. On the other hand, GDM, CSM and HPPD have high potential deposition rate. In the Aerosol Deposition Method (ADM), submicron particles were accelerated by a gas flow in the nozzle and ejected onto substrate. During impaction with substrate, part of particle’s kinetic energy is transformed into bonding energy between particles. Process is done without any additional source of energy. No additional procedure for densification of layer is necessary. In this paper we reported result of deposition of oxides (Al2O3; (Ni,Zn)Fe2O3; PZT [Pb(Zr0.52,Ti0.48)O3]) and non-oxide (AlN; MgB2) ceramics by ADM.
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