Processing parameters affecting cold spay coatings performances

In the present paper, the microstructural and mechanical properties of metal–metal cold spray deposits are described. Different spray particles coatings (Al-, Ti-, Ni-based particles) deposited on different substrates (Al-, Ti-, Fe-, Ni-, Mg-based bulk materials) were produced and their mechanical and microstructural properties were characterized. Microhardness, porosity, grain size and adhesion strength of the coatings were analyzed as a function of processing parameters such as particle velocity, particle dimensions, gas density, substrate hardness, and temperature. The results were employed to build a database used to obtain a provisional model through a multi-objective optimization software. For each different substrate and particle type, the working points were defined in terms of processing parameters to optimize mechanical and microstructural behavior of coatings. The error calculation of the final properties of the deposits demonstrated the precision of the developed model.     

The barrel aged beer wheel: a tool for sensory assessment

There has been an increasing interest in the wooden barrel aging of beer in breweries worldwide. Monitoring of the barrel aging process relies mostly on changes in sensory parameters over time. This may be difficult for teams or brewers with little or no appropriate experience. The beer sensory wheel presents a broad approach to sensory aspects and generalised attributes for many beer styles. Accordingly, this tool may result in confusion through excessive visual information. The work reported here is based on literature research and sensory panel analysis employing ultra-flash profile with the aim to build a new visual tool for wooden barrel aged beer. This will aid the evaluation, training and quality assessment of barrel aged beer. It also provides specific terminology to describe the sensory changes during the barrel aging process. This approach was used to elucidate the characteristics of different wood species (amburana, cabreúva and American oak), and evaluate the flavour transformation of wooden barrel aged beer compared to non-aged beer. The barrel aged beer wheel comprises attributes and references for flavour evaluation and also terms that define the main transformational pathways, namely oxidation, wood extraction and biotransformation. The wheel described here is intended to meet academic and professional needs for the quality assessment of wooden barrel aged beer based on sensory analysis. © 2020 The Institute of Brewing & Distilling     

Maturation related phenolic compounds in cachaça aged in new oak barrels

Aging cachaça in wooden barrels improves its chemical and sensory profile and adds quality. Maturation of distilled spirits is influenced by factors such as the species of wood to make the barrels, degree of internal toasting, number of uses of the barrel and aging time. The level of maturation of distillates can be determined based on the concentration of age marker phenolic compounds extracted from the lignin of the wooden barrel, as well as their relationships with each other. This study characterises the aging process of cachaça by analysing the mechanism of lignin degradation during maturation in new oak barrels for up to 60 months in order to establish the relationship between the age of the distillate and the content of phenolic compounds extracted from the wood. The evaluation was based on the analyses of liginin derived compounds using high‐performance liquid chromatography. The level of maturation of aged cachaça can be characterised by evaluating the low molecular weight lignin‐derived phenolic substances. The total amount of benzoic acids (vanillic and syringic acids) can be taken into consideration for predicting the level of maturation of distillates. Based on the composition of maturation related congeners, it is likely that for cachaça, each year of aging in new oak barrels corresponds to approximately five years of aging for spirits in general. © 2020 The Institute of Brewing & Distilling     

Chemical and microbiological quality of sugar cane juice influences the concentration of ethyl carbamate and volatile congeners in cachaça

The aim of this study was to assess the influence of heat treatment of sugar cane juice, supplementation with urea and double distillation on the concentration of volatile congeners (acetic aldehyde, ethyl acetate, n‐propyl, isobutyl and isoamyl alcohols and acetic acid) and contaminants (methanol, 1‐propyl and 2‐butyl alcohols, copper, and ethyl carbamate) in cachaça. Samples of fresh sugar cane juice, sugar cane juice submitted to heat treatment and contaminated sugar cane juice were supplemented (or not) with urea and fermented. The washes so obtained underwent single and double distillation. Supplementation with urea stimulated ethyl carbamate formation. The distilled products that originated from contaminated worts presented higher concentration of acetic acid and ethyl carbamate. Double distillation reduced the concentration of contaminants. The best quality pot still cachaça was obtained employing heat treatment of sugar cane juice, nonsupplementation with urea and double distillation. Copyright © 2015 The Institute of Brewing & Distilling     

Transmission Performance of MC-CDMA Hybrid Fiber-Radio Systems

This paper reports an analysis of the transmission performance of a hybrid broadband access system consisting of a fiber optic feeder and a millimeter-wave radio channel in the last mile. It is also assumed that the system adopts the multi-carrier code division multiple access (MC-CDMA) technique, that allows effective radio resource utilization and does not require a strong equalization. The analysis reveals that the impact of non-linear effects, mostly due to the non-linear optical source and secondarily due to non-ideal RF power amplifier characteristics, could prevent the good performance of the system as a whole, and indicates which are the good operating conditions for the systems.     

Cold-Sprayed Nanostructured Pure Cobalt Coatings

Cold-sprayed pure cobalt coatings were deposited on carbon-steel substrate. Submicrometer particles for spraying were produced via cryomilling. Deposits were produced using different processing conditions (gas temperature and pressure, nozzle-to-substrate distance) to evaluate the resulting variations in grain size dimension, microhardness, adhesion strength, and porosity. The coating mechanical properties improved greatly with higher temperature and carrying-gas pressure. The coating microstructure was analyzed as a function of spraying condition by transmission electron microscopy (TEM) observations, revealing many different microstructural features for coatings experiencing low or high strain rates during deposition.     

Crystallization Evolution of Cold-Sprayed Pure Ni Coatings

Cold spraying is a coating technology on the basis of aerodynamics and high-speed impact dynamics. Spray particles (usually 1-50 μm in diameter) are accelerated to high velocity (typically 300-1200 m/s) by a high-speed gas (preheated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval type nozzle. The coating forms through the intensive plastic deformation of particles impacting on the substrate at temperatures well below the melting point of the spray material. In the present paper, the main processing parameters affecting the crystallization behavior of pure Ni cold spray deposits on IN718 alloy are described. Various experimental conditions have been analyzed: gas temperature and pressure, nozzle to substrate distance. In particular, the study deals with those conditions leading to a strong grain refinement, with an acceptable level of the deposits mechanical properties. In precise spray conditions, a shift toward amorphous phases has been observed and studied. A systematic analysis of microstructural evolution, performed through TEM observations, as a function of processing parameters is presented.     

Processing Conditions Affecting Grain Size and Mechanical Properties in Nanocomposites Produced via Cold Spray

Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al₂O₃, Ni-BN, Cu-Al₂O₃, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.