具有最优玻璃形成能力的Zr-Co(Cu)-Al大块金属玻璃及其压缩性能（英文）

采用铜模吸铸法在三元Zr_(56)Co_(28)Al_(16)和四元Zr_(56)Co_(28)-xCuxAl_(16)(x=2,4,5,6,7,摩尔分数,%)非晶合金中形成大块金属玻璃(BMGs)。本研究主要目的是找到四元Zr Co(Cu)Al合金中形成大块金属玻璃的最优成分,并提高母合金的塑性。采用X射线衍射(XRD)技术、透射电镜(TEM)和差示扫描量热法(DSC)研究非晶合金的结构及其玻璃形成能力(GFA)。此外,利用压缩试验、显微硬度、纳米压痕和扫描电镜(SEM)讨论塑性提高的可能机制。含铜合金中玻璃形成能力最强的是Zr_(56)Co_(22)Cu_6Al_(16)合金,与基体合金相似。此外,Zr_(56)Co_(22)Cu_6Al_(16)大块金属玻璃的塑性从基体合金的3.3%显著增加到6%。最后,结合铜和钴的正混合热,讨论合金塑性和GFA的变化。     

Microstructural evolution mechanism during brazing of Hastelloy X superalloy using Ni–Si–B filler metal

The paper aims at understanding solidification phenomena and solid state precipitations during diffusion brazing of Hastelloy X nickel base superalloy using a ternary Ni–4.5Si–3.2 B (in wt-%) filler metal. The joint is featured by the formation of Ni-rich solid solution in an isothermal solidification zone, borides/silicide formation during eutectic-type solidification in an athermal solidification zone, on-cooling precipitation of fine nickel silicides in the joint centerline, in situ precipitation of Mo–Cr-rich borides in the diffusion affected zone and grain growth in the heat affected zone. The implication of the phase transformations on the joint properties is discussed. It is shown that Hastelloy X exhibited very fast isothermal solidification which can be attributed to its high Mo and Cr content that promotes in situ boride precipitation during brazing.     

Effect of Acidic and Basic Solutions on Electron Beam Irradiated Epoxy Nanocomposites Containing Nanoclay,CaCO3 and TiO2 Nanoparticles

High chemical resistance is the main prerequisites for materials that are intended to be utilized in usages such as chemicals storage containers production. Nanocomposites of epoxy resin containing nanoclay, CaCO₃ and TiO₂ nanoparticles were prepared and their chemical resistance was studied. Moreover, the effect of electron beam irradiation was explored. TEM micrographs proved the dispersion of nano-size particles in the polymeric matrix. XRD patterns showed an exfoliated structure for nanocomposite containing 1 % nanoclay and intercalated structures for nanocomposites with higher nanoclay contents. SEM showed the pits that appeared in epoxy/nanoclay structure due to chemical corrosion. Weight loss measurements revealed that an addition of 1 % nanoclay to the epoxy matrix is effective for improving the chemical properties of the polymer. Desirable effect of 100 kGy irradiation on chemical resistance properties of the samples was also observed in both acidic and basic environments.     

Maximum‐likelihood maximum‐entropy constrained probability density function estimation for prediction of rare events

This work addresses the problem of estimating complete probability density functions (PDFs) from historical process data that are incomplete (lack information on rare events), in the framework of Bayesian networks. In particular, this article presents a method of estimating the probabilities of events for which historical process data have no record. The rare‐event prediction problem becomes more difficult and interesting, when an accurate first‐principles model of the process is not available. To address this problem, a novel method of estimating complete multivariate PDFs is proposed. This method uses the maximum entropy and maximum likelihood principles. It is tested on mathematical and process examples, and the application and satisfactory performance of the method in risk assessment and fault detection are shown. Also, the proposed method is compared with a few copula methods and a nonparametric kernel method, in terms of performance, flexibility, interpretability, and rate of convergence. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1013–1026, 2014     

Antioxidant,antifungal, water binding,and mechanical properties of poly(vinyl alcohol) film incorporated with essential oil as a potential wound dressing material

In this study, the properties of poly (vinyl alcohol) (PVA) films incorporated with Zataria multiflora essential oil (ZMO) as a potential antioxidant/antibacterial material was investigated. PVA films were prepared from PVA solutions (2% w/v) containing different concentrations of ZMO. Water solubility, moisture absorption, water swelling, and water vapor permeability for pure PVA films were 57 ± 1.1, 99 ± 3.2%, 337 ± 8%, and 0.453 ± 0.015 g mm/m² h, respectively. Incorporation of ZMO into PVA films caused a significant decrease in water swelling and moisture absorption and increase in solubility and water vapor permeability. Tensile strength, elastic modulus, and elongation at break for pure PVA films were 13.5 ± 0.61 MPa, 15.2 ± 0.8 MPa, and 216 ± 4%, respectively. Incorporation of ZMO into the PVA films caused a significant decrease in tensile strength and elastic modulus and increase in elongation at break of the films. Pure PVA film showed UV‐visible light absorbance ranging from 280 to 440 nm with maximum absorbance at 320 nm. Addition of ZMO caused a significant increase in light absorbance and opacity. PVA films exhibited no antioxidant and antifungal activities, whereas PVA/ZMO films exhibited excellent antioxidant and antifungal properties. Although the bioactivity PVA films were improved by the addition of ZMO, however, the mechanical properties and water binding capacity of the films were weaken slightly. Thus, ZMO emulsified in the ethanol not compatible with PVA matrix and more suitable emulsifier was needed in order to obtain strong film with higher mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40937.     

Effect of lignin removal on mechanical,thermal, and morphological properties of polylactide/starch/rice husk blend used in food packaging

The aim of this work was to investigate the possibility of using cost‐effective natural filler in a biodegradable polymer and find new set of materials for green biocomposites to be used in food packaging. In this regard, rice husk (RH) and bleached rice husk (BRH) have been used in the form of powder and the effect of lignin removal on mechanical and thermal properties of prepared composites with poly(l ‐lactide) and starch were studied. Using FTIR technique, the lignin removal from RH has been approved. The tensile, charpy impact, and hardness tests were implemented to investigate the mechanical properties. It was concluded that filler caused increase both in the toughness and the Young modulus of samples. It was also found that the lack of lignin in BRH samples improves the mechanical properties. It was clearly observed that the BRH samples show larger modulus, charpy impact strength, and hardness compared to those filled with RH. Despite larger values for the elongations at break of RH samples, the mechanical properties showed a significant improvement (between 25 and 50% improvements) on lignin removal. The differential scanning calorimetry thermograms revealed an improvement in crystallization behavior and reduction of T_g from 47 to 31°C in the case of BRH‐filled samples. Finally, due to the removal of toxic lignin in the samples and modification of mechanical properties by this method, the BRH could have the ability of wide use in the bioplastics and food packaging industries. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41095.     

Hybridization effect of basalt and carbon fibers on impact and flexural properties of phenolic composites

In this study, the impact and flexural properties of woven basalt fiber/phenolic (BFP), woven carbon fiber/phenolic (CFP) and woven basalt/woven carbon hybrid phenolic (BCFP) composites are investigated. The hybridization effect of woven basalt and woven carbon fibers on the impact energy absorption and flexural properties is investigated for various weight ratios of basalt/carbon hybrid fibers such as 1:0, 0.83:0.17, 0.68:0.32, 0.61:0.39, 0.34:0.66 and 0:1. It is found that the impact properties of the composites are strongly improved when the basalt fiber increased. Impact energy absorption of CFP composite showed a regular trend of increase with increasing weight ratio of basalt fiber in hybrid fiber composite. The lowest impact energy absorption values are found for the composites with weight ratio 0:1 (CFP), with average of 70 kJ/m². Corresponding values for energy absorptions are obtained for 0.83:0.17, 0.68:0.32, 0.61:0.39, 0.34:0.66 basalt/carbon weight ratio in hybrid composites. The impact energy absorption of hybrid composites (BCFP) shows the highest value with an average of 219 kJ/m², when the weight ratio of 0.83:0.17 is used. Finally, the impact energy absorption of BFP composites with the weight ratio of 1:0 shows the highest value of 268 kJ/m². The experimental evidence shows that the hybrid composites based on combinations of stiff carbon fibers and tough basalt fibers have good flexural properties and therefore, they can be used as promising materials in a number of engineering sectors such as the protective structures.     

A new approach in modeling of mechanical properties of nanocomposites: effect of interface region and random orientation

The Young’s modulus of polymer nanocomposites is predicted using a numerical approximation system (NAS) model based on fully exfoliated nanoparticles, random orientation (with platelet and cylindrical forms), and nanoparticles of specific shapes (e.g., square platelets, nanotubes, and spherical). The thickness of interface between the polymer matrix and nanoparticles which plays an important role in reinforcing mechanism of nanocomposites is also employed in NAS model as a crucial parameter. The modulus of interface region on the surface of nanoparticle is another significant parameter which is taken into account through mathematical modeling procedure of NAS model as it may indicate the manner by which the polymer matrix bonds to the surface of nanoparticles. NAS model proposes a general formulation through which the Young’s modulus of a nanocomposite could be easily predicted, while the involving parameters change due to the shape of nanoparticle (e.g., platelet, cylindrical or spherical). The final predications of NAS model are validated by comparing them with the results of tensile tests for polyamide (PA)/Cloisite 30B nanocomposite system and the results reported in other similar studies on the mechanical properties of polymer nanocomposites.     

Deposition of Superhydrophobic Fatty Acid-Coated Al2O3 Films by Spray Pyrolysis Method: Effect of Dispersion Mediums on Morphology and Roughness of the Layer

Protection of Metals and Physical Chemistry of Surfaces - In the present study, the superhydrophobic surface was fabricated by spray pyrolysis method. The precursor for the spray process was the...