FTIR examination of preservative retention in beech wood (Fagus sylvatica L.)
A method of FTIR examination of preservative retention in beech wood structure was developed. Beech wood samples of different preservative content were prepared using low pressure preservation process in laboratory conditions. Then samples were homogenized in a laboratory mill and measurements were performed using FTIR spectrometer with attenuated total reflectance unit. Pure preservative was also measured and from its spectrum 1,555 cm−1 absorption band was chosen as the characteristic for preservative. 1,027 and 1,370 cm−1 were absorption bands characteristic for wood which were chosen as reference peaks. Values of two absorbance ratios, A1,555/A1,027 and A1,555/A1,370 were correlated with the preservative content in particular samples. Correlation coefficients were 0.8390 and 0.8313, respectively.
Univariate and Multivariate Analysis of Tannin-Impregnated Wood Species Using Vibrational Spectroscopy
Vibrational spectroscopy is one of the most powerful tools in polymer science. Three main techniques—Fourier transform infrared spectroscopy (FT-IR), FT-Raman spectroscopy, and FT near-infrared (NIR) spectroscopy—can also be applied to wood science. Here, these three techniques were used to investigate the chemical modification occurring in wood after impregnation with tannin–hexamine preservatives. These spectroscopic techniques have the capacity to detect the externally added tannin. FT-IR has very strong sensitivity to the aromatic peak at around 1610 cm−1 in the tannin-treated samples, whereas FT-Raman reflects the peak at around 1600 cm−1 for the externally added tannin. This high efficacy in distinguishing chemical features was demonstrated in univariate analysis and confirmed via cluster analysis. Conversely, the results of the NIR measurements show noticeable sensitivity for small differences. For this technique, multivariate analysis is required and with this chemometric tool, it is also possible to predict the concentration of tannin on the surface.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.