We systematically investigate the formation of nanostructures in magnetron-sputtered Au films using a CO2 laser. By comparing the optical properties and surface morphologies of Au films on different kinds of substrates before and after laser irradiation with different laser powers and irradiation times, we find that the nanostructures are most rapidly formed in the Au film with 5 nm thickness on a thin glass substrate. With the laser power of 6 W and a beam diameter of ~10 mm at the Au film, only a few tens of seconds of irradiation time is sufficient to induce nanostructures with the area size of ~10 mm in the 5 nm Au film on a thin glass substrate.
We demonstrate the rapid in situ synthesis of polymer-metal nanocomposite films using a CO2 laser at 10.6 μm. The mechanism of our method is that the precursor of the metal nanoparticles, i.e., the metallic ions, is very rapidly reduced in the laser-heated polymer matrix without any reducing agent. Unlike other known laser-induced reduction methods using UV lasers, which produce radicals to promote reduction, the CO2 laser energy is mainly absorbed by the glass substrate, and the laser-heated substrate heats the polymer matrix through heat diffusion to promote reduction. The superiority of the use of CO2 lasers over nanosecond visible~UV lasers is also demonstrated in terms of the damage to the film. The developed method can be a new alternative to quickly synthesize a variety of polymer-metal nanocomposite films.
Carbon fibre reinforced thermoplastics (CFRTP) attract attention due to their excellent features of specific strength, specific modulus, productivity and recyclability in various fields. In this research, polycarbonate (PC) was used as a matrix of CFRTP with high impact strength compared with other plastics. However, at high temperature and high humidity conditions, hydrolyzation of an ester linkage in PC occurs, at the same time crazes and cracks also occur and the mechanical properties of PC deteriorate. Water absorption testing and tensile testing were also carried out to investigate the influence of water absorption on the mechanical properties on the CF/PC composite and PC resin. Single fibre pull-out tests were carried out to investigate the influence of water absorption on CF/PC interfacial shear strength. The water gain of PC was saturated at 0.46%. For the CF/PC composite, water was absorbed not only in the PC resin but also in the fibre/matrix interface. The tensile strength of the PC resin showed a tendency to decrease as the water absorption time increases, while the tensile modulus of PC did not change. The CF/PC composite showed a tendency to decrease for tensile strength and modulus when water absorption time is at 400 hours. The CF/PC interfacial shear strength showed a tendency to decrease as the water absorption time increases.
In-situ synthesis of metal-polymer nanocomposite films by irradiating a CO2 laser for several seconds is a new alternative to fabricate metal-polymer nanocomposite films. The main features of this method are that the number density of the synthesized metal nanoparticles is very high so that the optical density easily exceeds 0.5~1.5 for the film thickness of ~200 nm, and owing to the short fabrication time and the use of non-focused laser beam, largescale processing is possible. For this technique to be applicable for a variety of purposes an important question is how and how much we can control the film properties. In this work we demonstrate that the size and size distribution of metallic nanoparticles in the synthesized nanocomposite films can be well-controlled by the choice of the laser power and irradiation time as well as the concentrations of nanoparticle precursor. Properties of the synthesized films can be roughly understood by considering the diffusion of metallic ions, atoms, and nanoparticles in the polymer film under the elevated temperature induced by the CO2 laser.
PZT thin films were prepared by the MOCVD methd. Bisdipivaloylmethanato lead, zirconium tetra-t-butoxide and titanium tetra-i-prpxide and oxygen were used as source materials. A typical deposition rate was 50-200fumin over a 6-inch diam. substrate. The physical and the electrical characteristics were evaluated Polycrystallized films with the well developed perovskite phase were formed on R(111) substrate at 600-700oC. The dielecuic constant-and tan6 were 65-3000 and 0.009-O.t33. A typical dielectric break{own voltage of 2400A thick PZ:l film was zLV, while the leakage"6orrent of 0.26pA/cm2 at 5V ;;; achieved. A film formed by this method showed the ferroelectric characteristic.
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