Hybrid Sol-gel Technology Research Articles

Corrosion protection on texturized steel moulds for polymeric products by sol–gel anti-adherent coatings

During the moulding of polymeric pieces, the important temperatures involved, and the gases produced by decomposition of components from the polymer can induce corrosion on the working surface of the steel mould. Polymers can also stick to the mould surface, being their separation (demoulding) one of the critical aspects in their processing. Demoulding agents typically used in this process are expected to contribute in some extend to protect the mould against corrosion. In this work, hybrid sol–gel technology for anti-adherent coatings presented in previous papers is extended to formulations doped with different metallic precursors of proven chemical and wear resistance such as Zn, Ti, and Zr, with the aim to increase the corrosion resistant at the same time that keep good demoulding properties. Different synthetic routes one-pot or two components were followed depending on the doped agent. Sol–gel formulations were applied onto steel substrates by controlled dip coating technique, resulted in ultra-thin films of ∼0.15 µm, being capable to protect micro texturized steel moulds. Hardness of these films was superior (10H) to those formulations with fluorosilane and PDMS used as reference. Corrosion protection was evaluated obtaining good results in both polarization resistance and corrosion rate for Zn (5232 Ω × cm2, 0.08 mm/year), protecting the bare steel up to 6.5 times more in terms of annual corrosion, followed by Zr and Ti. Their behaviour as anti-adherent coating was also discussed and compared with fluorosilane and PDMS-based coatings.

Performance of astronomical beam combiner prototypes fabricated by hybrid sol-gel technology

Integrated optics coaxial two, three and four telescope beam combiners have been fabricated by hybrid sol-gel technology for astronomical applications. Temporal and spectral analyses of the output interferometric signal have been performed, and their results are in mutual good agreement. The results of the characterization method employed are cross-checked using contrast measurements obtained independently, demonstrating that the chromatic differential dispersion is the main contributer to contrast reduction. The mean visibility of the fabricated devices is always higher than 95 %, obtained using a source with spectral bandwidth of 50 nm. These results show the capability of hybrid sol-gel technology for fast prototyping of complex chip designs used in astronomical applications.

Hybrid sol-gel planar optics for astronomy

Hybrid sol-gel planar optics devices for astronomy are produced for the first time. This material system can operate from the visible (0.5 microm) up to the edge of astronomical J-band (1.4 microm). The design, fabrication and characterization results of a coaxial three beam combiner are given as an example. Fringe contrasts above 94% are obtained with a source with spectral bandwidth of 50 nm. These results demonstrate that hybrid sol-gel technology can produce devices with high quality, opening the possibility of rapid prototyping of new designs and concepts for astronomical applications.

Photonic circuits writing with UV pulsed laser

Photonics technology is employed in a growing number of applications. Biological and chemical sensors (E. Udd, Fiber Optic Sensors: An Introduction for Engineers and Scientists, Wiley, New York, 1991 [1]) for health and environment demand an adaptable technology. Network development towards the end-user requires more interconnecting components. Vision, lighting, data processing in hostile environment (spatial, military) need specific technologies. A flexible and low-cost process using good quality material is necessary. The sol-gel process is a chemical method to fabricate glasses at ambient pressure and moderate temperature. Hybrid materials (H.K. Schmidt et al., Proc. SPIE 3136, 220 (1997) [2]), mixing organic and inorganic parts, offer the advantages of polymer-like materials and glasses. We report on a new hybrid sol-gel technology to overcome the drawbacks of the formerly presented one (H. Krug, F. Teillantes, P.W. Oliviers, and H. Schmidt, Proc. SPIE 1758, 448 (1992) [3]). We present the material synthesis, an accurate and flexible fabrication process based on a pulsed UV laser lithography system and the characterisation of the optical waveguides and photonic circuits realised.

Low-Loss Photopatternable Hybrid Sol–Gel Materials

Hybrid sol-gel technology has proved its usefulness in the field of micro-optics. Indeed, it makes it possible to manufacture optical microcomponents by processes much simpler than those currently used, particularly when photopatternable materials are employed. However, for wavelengths in the near infrared window (NIR), this process is confronted with a major problem which results from the significant optical absorption of this type of materials, in particular around 1550 nm. The aim of this paper is to describe the origin of the losses of some hybrid sol-gel materials of direct interest in micro-device fabrication in order to propose solutions to achieve a greater transparency in the NIR region. The intrinsic absorption of the precursors was first of all considered since it is crucial to pursue the final goal of decreased losses. Then, the principal parameters of the sol-gel synthesis were studied. Among them, the thermal treatment conditions, the hydrolysis ratio and the controlled addition of transition metal alkoxides allow an improvement of the material transparency, at 1550 nm most particularly. This last point was considered with the highest attention, and NIR and NMR spectroscopies were employed to explain how the addition of zirconium alkoxides at the end of the reaction makes it possible to considerably decrease the losses in the material.

Photosensitive Materials for Integrated Optic Applications

This article presents results of device fabrication using UV processing of materials and integrated optic components produced by flame hydrolysis deposition and hybrid sol-gel technology. Photosensitive materials were employed in the fabrication of channel waveguides and channel photo-imprinted waveguides incorporating Bragg gratings through single and double-step exposure.

Sol-Gel Derived PZT Thick Films with Nano-Sized Microstructure

ABSTRACTLead zirconate titanate (PZT) films are promising for acoustic micro-devices applications because of their extremely high electromechanical coupling coefficients and excellent piezoelectric response. Thicker PZT films are crucial for these acoustic applications. A hybrid sol-gel technology has been developed as a new approach to realize simple and cost-effective fabrication of high quality PZT thick films. In this paper, PZT53/47 thick films with a thickness of 5–50 μm are successfully deposited on Pt-coated silicon wafer by using the hybrid sol-gel technology. The obtained PZT thick films are dense, crack-free, and have a nano-sized microstructure. The processing parameters of this technology have been evaluated. The microstructure of the film has been observed using field-emission scanning electron microscopy and the crystallization process has been monitored by the X-ray diffraction. The thick films thus made are good candidates for fabrication of piezoelectric diaphragm which will be an essential element of microspeaker and microphone arrays.