Modification of Aerosol Gold Nanoparticles by Nanosecond Pulsed-Periodic Laser Radiation

This study investigates the processes of interaction of nanosecond pulsed-periodic laser radiation with the flow of aerosol agglomerates of gold nanoparticles synthesized in a spark discharge. Nanoparticles in a gas flow are spatially separated nano-objects whose interaction with each other and with the walls of an experimental cell was insignificant. Therefore, the energy absorbed by nanoparticles was used only for their own heating with further shape and size modification and on heat transfer to the surrounding gas. In the research, we used laser radiation with wavelengths of 527 and 1053 nm at pulse energies up to 900 µJ and pulse repetition rates up to 500 Hz. The dynamics of changes in the nanoparticles size during their sintering process depending on the laser pulses energy is characterized by an S-shaped shrinkage curve. Complete sintering of the initial agglomerates with their transformation into spherical nanoparticles is achieved by a series of impacting laser pulses. The result of nanoparticles’ laser modification is largely determined by the pulse energy and the efficiency of the nanoparticles’ radiation absorption.

The Sintering and Electrical Properties of La0.5Sr0.5Co0.96Ni0.04O3-δ Ceramics with B2O3- CuO Addition

The performance of adding 0–3 wt% B2O3-CuO as a sintering aid to lower the sintering temperature of La0.5Sr0.5Co0.96Ni0.04O3-δ (LSCN) was investigated through solid-state reaction method. Results of linear shrinkage curve, bulk density, and microstructure indicated that BCu addition could promote the sintering process and enhance the densification of LSCN ceramics. With the increase of BCu content, low absolute value of TCR could be achieved, while the conductivity was deteriorated obviously. For LSCN ceramics sintered at 950 °C, the bulk density, conductivity, and TCR were worse than those sintered at higher temperatures. Consequently, the BCu-doped LSCN ceramics might not suitable for the application in the field of LTCC.

Use of a three-dimensional scanner for shrinkage curve tests

A procedure is proposed for conducting shrinkage limit tests using a three-dimensional (3D) scanner. Shrinkage limit tests were conducted on 27 different soils of varying plasticity. In this study only eight of the shrinkage curves were determined using 3D scanning techniques, while the remaining 19 were taken from literature. An individual specimen was scanned between 30 and 50 times to produce a high-resolution shrinkage curve. Shrinkage curves for each material were obtained by curve fitting a shrinkage model to the measured dataset. The primary intent of the research was to relate the shrinkage curve equation to the plasticity of a given soil. Using linear regression analysis, an empirical correlation was developed to reasonably relate parameter csh from the shrinkage model to the ratio of the plastic and liquid limits. The shrinkage curves produced based on the model have an average difference of ∼1.2% in terms of measured void ratio and predicted void ratio. The method was demonstrated to be robust for materials of low, medium, and high plasticity. The proposed methodology also presents a means of estimating a shrinkage curve in its entirety based solely on the volume of an air-dried sample, the specific gravity, and Atterberg limits of the specimen. This effectively reduces the amount of work needed to derive the shrinkage curve and could potentially reduce the time for a shrinkage limit test by half or more.