Laser assisted fabrication of porous polymer MEMS with nano structured additives
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Laser assisted fabrication of porous polymer MEMS with nano structured additives Igor V. Shishkovsky1 and Yuri G. Morozov2 1 P.N. Lebedev Physics Institute of Russian Academy of Sciences, Samara branch, Novo-Sadovaja st. 221, Samara 443011, Russia. [email protected] 2 Institute of Structural Macrokinetics and Materials Science (ISMMS), RAS, Chernogolovka, Moscow, 142432 Russia. ABSTRACT Selective laser sintering (SLS) process was used to obtain nanostructured porous 3D objects consisting of Ni or/and Cu nanoclusters enveloped with a polycarbonate (PC) matrix for M/NEMS applications. The liquid phase SLS process was performed in air or Ar. The powder mixtures of Ni + PC in proportions 1:1, 1:2 (Ni particle size ranged from 27 to 184 nm) and Cu + PC = 1:9, 1:4, 3:7 (Cu particle size ranged from 76 to 90 nm) and a cw YAG:Nd+3 laser (P = 4– 10 W) with defocused laser beam were used. Optimal regimes of laser treatment as monolayer as layerwise 3D part manufacturing in above mention nano compositions were determined. The scanning electronic microscopy (SEM) equipped EDX and qualitative XRD analysis showed that content and size of nanoparticles are remained unaffected after the liquid-phase sintering. It was shown a principle possibility of functional graded 3D parts fabrication via the interleaving of the metal - polymer powdered compositions with Ni and/or Cu additives, which ensures the nano particle sizes conservation. Proposed approach is opened a new way by deliberated M/NEMS device synthesis. Alternation of ferromagnetic and non-magnetic layers with Ni and/or Cu core – polymer shell structures was provided the interesting electro-physical properties of such devices. INTRODUCTION Nanoparticles are promising candidate as the solid lubricant, in conducting and magnetic materials, and in pressure cells and hydrogen storage devices also. Multilayers with giant magnetoresistance, which could be realized in the layers interleaving ferromagnetic and nonmagnetic metals, have attractive applications [1-3]. With the decrease of particle sizes from the micro- to the nano- level, the specific surface area to volume ratios grows and, consequently, the chemical activity of nanoparticles follows to this behavior. The direct multilayer fabrication of the nanoparticles is a difficult task. It is known, that the sintering is the thermally activated process, which compulsorily must be accompanied by the nanoparticle coagulation in the micrometer conglomerations. To stabilize the nanoparticles in the polymeric matrix is attractive [4], because of this makes possible the organization of beforehand determined distribution of nanoparticles by porous polymer structure. It is allow to protect them from the undesirable oxidation and even to attempt the functional graded structures design on this way. Therefore, the polymer mixture sintering is represented as more optimum due to the temperature for the polymer sintering is deliberately lower than temperatures under which the nanoparticles will begin actively to consolidate. Nano size core/polym
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