Deposition of Gadolinia-Doped Zirconia Layers Using Metalorganic Compounds at Low Temperatures

This paper shows the results of an investigation on the synthesis of non-porous and nanocrystalline ZrO2-Gd2O3 layers by metalorganic chemical vapor deposition (MOCVD) with the use of Zr(tmhd)4 (tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)zirconium(IV)) and Gd(tmhd)3 (tris(2,2,6,6-tetramethyl-3,5-heptanedionato)gadolinium(III)). Argon and air were used as carrier gases. The molar content of Gd(tmhd)3 in the gas reaction mixture was as follows: 10% and 20%. The layers were synthesized on tubular substrates made of quartz glass at the temperatures of 550–700 °C. Synthesis conditions were established using the Grx/Rex2 expression (Gr is the Grashof number; Re is the Reynolds number; x is the distance from the gas inflow point). The value of this criterion was below 0.01. ZrO2-Gd2O3 layers synthesized at 600–700 °C were crystalline. When the molar content of Gd(tmhd)3 in the gas reaction mixture was 10 mol.%, a relationship between the chemical composition of the gas reaction mixture and that of the deposited layer could be observed. The synthesized layers underwent scanning electron microscopy, as well as X-ray analysis. The transparency of coated and uncoated glass was tested using UV–Vis spectroscopy. Their chemical composition was examined with the use of an EDS analyzer.

Fouling Release Coatings Based on Acrylate–MQ Silicone Copolymers Incorporated with Non-Reactive Phenylmethylsilicone Oil

Copolymers containing MQ silicone and acrylate were synthesized by controlling the additive amount of compositions. Subsequently, fouling release coatings based on the copolymer with the incorporation of non-reactive phenylmethylsilicone oil were prepared. The surface properties of the coating (CAMQ40) were consistent with that of the polydimethylsiloxane (PDMS) elastomer, which ensured good hydrophobicity. Moreover, the seawater volume swelling rate of all prepared coatings was less than 5%, especially for CAMQ40 with only 1.37%. Copolymers enhanced the mechanical properties of the coatings, while the enhancement was proportional to the molar content of structural units from acrylate in the copolymer. More importantly, the adhesion performance between the prepared coatings and substrates indicated that pull-off strength values were more than 1.6 MPa, meaning a high adhesion strength. The phenylmethylsilicone oil leaching observation determined that the oil leaching efficiency increased with the increase in the structural unit’s molar content from MQ silicone in the copolymer, which was mainly owing to the decrease in compatibility between oil and the cured coating, as well as the decrease in mechanical properties. High oil leaching efficiency could make up for the decrease in the biofouling removal rate due to the enhancement of the elastic modulus. For CAMQ40, it had an excellent antifouling performance at 30 days of exposure time with more than 92% of biofouling removal rate, which was confirmed by biofilm adhesion assay.

Influence of Working Fluid Composition on the Optimum Characteristics of Blended Supercritical Carbon Dioxide Cycles

The supercritical Carbon Dioxide power cycle technology has attracted growing interest from the scientific community, becoming one of the most important options currently considered for CSP applications. This is thanks to its high thermal efficiency, even at moderate turbine inlet temperatures, and small footprint. Nevertheless, sCO2 power cycles require a fairly low compressor inlet temperature to exploit their full thermodynamic potential. When this cannot be achieved, as it is usually the case for Concentrated Solar Power plants where ambient temperatures are high, the interest of the technology is compromised. To compensate for this effect, the SCARABEUS project is working on the development of certain chemical dopants that could be added to the raw CO2, obtaining new working fluids with the same or even better performance than pure CO2 even at higher minimum cycle temperatures. This paper studies the impact of using CO2 mixtures blended with Hexaflurorobenzene (C6F6) and Titanium Tetrachloride (TiCl4). It is found that these mixtures enable thermal efficiencies that are higher than if pure CO2 were used. The efficiency gain can be as high as 3 percentage points, depending on the dopant used and the operating conditions considered. In addition to this absolute performance gain, the paper reveals that there are additional degrees of freedom that enable more effective cycle optimisation. These are the dopant molar content, not only its composition, and the cycle layout used. When this is studied, it is found that the optimum molar content ranges from 10 to 20% and that the layouts of interest when using mixtures are simpler than if plain CO2 were used. These results open the way for a significant performance enhancement of Concentrated Solar Power plants.

Preparation and Characterization of Biobased Lignin-Co-Polyester/Amide Thermoplastics

More than 23 million tonnes of lignin are produced annually in the US from wood pulping and 98% of this lignin is burnt. Therefore, creating products from lignin, such as plastics, offers an approach for obtaining sustainable materials in a circular economy. Lignin-based copolymers were synthesized using a single pot, solvent free, melt condensation reaction. The synthesis occurred in two stages. In the first stage, a biobased prepolymer consisting of butanediol (BD, 0.8–1 molar content) and a diacid (succinic (SA), adipic (AA) and suberic acids (SuA), with varying amounts of diaminobutane (DAB, 0–0.2 molar content) was heated under vacuum and monitored by Fourier transform infra-red (FTIR) spectroscopy and electrospray ionization-mass spectrometry (ESI-MS). In the second stage, prepolymer was mixed with a softwood kraft lignin (0–50 wt.%) and further reacted under vacuum at elevated temperature. Progression of the polymerization reaction was monitored using FTIR spectroscopy. The lignin-copolyester/amide properties were characterized using tensile testing, X-ray diffraction (XRD), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Lignin co-polymer tensile (strength 0.1–2.1 MPa and modulus 2 to 338 MPa) properties were found to be influenced by the diacid chain length, lignin, and DAB contents. The lignin-copolymers were shown to be semi-crystalline polymer and have thermoplastic behavior. The SA based copolyesters/amides were relatively stiff and brittle materials while the AA based copolyesters/amides were flexible and the SuA based copolyesters/amides fell in-between. Additionally, > 30 wt.% lignin the lignin- copolyesters/amides did not exhibit melt behavior. Lignin-co-polyester/amides can be generated using green synthesis methods from biobased building blocks. The lignin- copolyesters/amides properties could be tuned based on the lignin content, DAB content and diacid chain length. This approach shows that undervalued lignin can be used in as a macromonomer in producing thermoplastic materials.

Vertical Alignment of Liquid Crystals on Comb-Like Renewable Chavicol-Modified Polystyrene

This study demonstrates liquid crystal (LC) alignment behaviors on the surface of phytochemical-based and renewable chavicol-modified polystyrene (PCHA#, # = 20, 40, 60, 80, and 100, where # represent the molar content of chavicol moiety in the side group) via polymer modification reactions. Generally, a LC cell fabricated with a polymer film containing a high molar content of the chavicol side group exhibited a vertical LC alignment property. There is a correlation between the vertical alignment of LC molecules and the polar surface energy value of the polymer films. Therefore, vertical LC alignment was observed when the polar surface energy values of these polymer films were smaller than about 1.3 mJ/m2, induced by the nonpolar chavicol moiety having long and bulky carbon groups. Aligning stability under harsh conditions such as ultraviolet (UV) irradiation of about 5 J/cm2 was observed in the LC cells fabricated from PCHA100 film. Therefore, it was found that the plant-based chavicol-substituted polymer system can produce an eco-friendly and sustainable LC alignment layer for next-generation applications.

Alignment Layer of Liquid Crystal Using Plant-Based Isoeugenol-Substituted Polystyrene

We synthesized a series of renewable and plant-based isoeugenol-substituted polystyrenes (PIEU#, # = 100, 80, 60, 40, and 20, where # is the molar percent content of isoeugenol moiety), using polymer modification reactions to study their liquid crystal (LC) alignment behavior. In general, the LC cells fabricated using polymer film with a higher molar content of isoeugenol side groups showed vertical LC alignment behavior. This alignment behavior was well related to the surface energy value of the polymer layer. For example, vertical alignments were observed when the polar surface energy value of the polymer was smaller than approximately 3.59 mJ/m2, generated by the nonpolar isoeugenol moiety with long and bulky carbon groups. Good alignment stability at 100 °C and under ultraviolet (UV) irradiation of 15 J/cm2 was observed for the LC cells fabricated using PIEU100 as a LC alignment layer. Therefore, renewable isoeugenol-based materials can be used to produce an eco-friendly vertical LC alignment system.

Study on the Effect of Si-Al Components in Pulverized Coal Ash on Corrosion in Heating Surface of Biomass Boiler

Pulverized coal ash can be used as an additive to reduce corrosion on heating surface of biomass boiler. Biomass ash and pulverized coal ash were mixed and coated on the metal surface for experiment; the results showed that the corrosion rate of the metal decreases by adding pulverized coal ash. With the increase of additive content, the corrosion gradually reduces. The effect of different pulverized coal ash on corrosion is different, but as the proportion of pulverized coal ash increases, the effect tends to be close. When the molar content of (Si+Al)/(Na+K) is about 2 and the ratio of Si/Al is about 1, the pulverized coal ash additive works best.

Effect of A-/B-site Doping on Oxygen Non-Stoichiometry, Structure characteristics, and O2 Releasing Behavior of La1−xCaxCo1−yFeyO3−δ Perovskites

Oxy-fuel combustion is one of the proposed technologies with the potential to achieve zero CO2 emission. La1−xCaxCo1−yFeyO3−δ (LCCF) perovskites are promising materials with high selectively for oxygen. In this study, the oxygen non-stoichiometry of perovskites LCCF was investigated by means of iodometric titration. LCCF was prepared using the liquid citrate method, and the phase structures were identified by X-ray diffraction. Fixed-bed experiments were performed to study the oxygen desorption performance of LCCF. The oxygen deficiency of LCCF increased with increasing Ca molar content of A site, but the value of δ of LCCF with increasing Fe molar content in B site is nearly constant. Experimental observation demonstrated that the O2 release amount of LCCF does not depend on oxygen non-stoichiometry δ generated from A-site doping. At the same time, doping Fe in B site has an obvious impact on the oxygen desorption amount.