Although electrostatic actuators have a simple structure and are lightweight, their range of application is limited because a high applied voltage of more than several kilovolts is required for practical use. Since the force acting between the electrodes of an electrostatic actuator is determined by the electric charge accumulated at the electrode/dielectric interface, the focus is on spontaneous polarization of ferroelectrics to increase the charge. As the ferroelectric material, a nematic liquid crystal material with a spontaneous polarization of 5 μC cm −2 is used. It is demonstrated that a force of 1.3 N is generated at an applied electric field of 0.5 MV m −1 . This force is 1200 times higher than that for standard paraelectric materials with a dielectric constant of ten. Further, the generated force responds linearly to the applied voltage, whereas it is proportional to the square of the applied voltage for paraelectric materials. The actuator function of this ferroelectric is examined using a double-helical coil electrode fabricated using a 3D printer. It can be successfully operated at a voltage of several tens of volts. Under an electric field of 0.25 MV m −1 , a remarkable contraction of 6.3 mm occurs, corresponding to 19% of the original length.

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Pd-decorated carbon nanotube (CNT) nanocomposites were added to a UV photopolymer resin to be used as the ink in the printing of three-dimensional (3D) structures. The nanocomposites were prepared with a UV-induced reduction method, in which Pd nanoparticles with a size ranging from 10 to 150 nm were produced and decorated on CNTs. The printed 3D structures from the resin containing 1.0 wt % Pd-decorated CNTs exhibited much improved mechanical properties, achieving a 40% enhancement in fracture strength and a 40% increase in microhardness over the 3D structures printed from the bare resin. In the presence of Pd-decorated CNTs as catalyst seeds, further deposition of defect-free, nearly conformal Ni–P layer on the 3D-printed structures at a high deposition rate can be realized. The cross-cut adhesion testing revealed a significantly enhanced adhesion between the deposited Ni–P layer and the 3D-printed structures. The metallized 3D-printed structures displayed superior electrical conductivity, showing an electrical resistance down to 0.11 Ω as 1.0 wt % Pd-decorated CNTs were incorporated. The findings from this work highlight the merits of employing Pd-decorated CNTs as both mechanical property enhancer and catalyst seeds in the advanced manufacturing of 3D-printed structures.

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．はじめにめっき技術は -------------------------------------------------------------------------------------------小特集：新発想めっき技術(1)セット 撹拌 (2)乳濁化＋反応 図 1 超臨界二酸化炭素エマルションを用いた無電解めっき （無電 解 SNP） の反応手順