Fracture behavior of low carbon MgO–C refractories using the wedge splitting test

The fracture behavior of low carbon MgO–C refractories containing various carbon sources were investigated by means of the wedge splitting test and microscopic fractographic analysis to evaluate quantitatively their thermal shock resistance in the present work. The results showed that the addition of various nanocarbons in MgO–C specimens can lead to more tortuous crack propagation path during the wedge splitting test and much better thermal shock resistance compared to the specimen with flaky graphite as carbon source; particularly, the specimen containing carbon nanotubes had the most outstanding thermal shock resistance. Also, it was suggested from the correlation analysis that the increase of the specific fracture energy and interface crack propagation as well as the decrease of the modulus of elasticity, coefficient of thermal expansion and transgranular crack propagation can contribute to an improvement of thermal shock resistance of MgO–C refractories.     

Electrochemical noise analysis on the crevice corrosion behavior of Ni–Cr–Mo–V high strength steel using recurrence plots

This article makes a study of electrochemical noise analysis on the crevice corrosion behavior of Ni–Cr–Mo–V high strength steel using recurrence plots. The crevice corrosion behavior of Ni–Cr–Mo–V high strength steel was investigated by the electrochemical noise (EN) technique and SEM observation. The experimental results reveal that the crevice corrosion could be distinguished by three stages including induction stage, transformation stage, and stable stage. While increasing the growth probability of metastable corrosion, the presence of crevice decreases the initiation rate of metastable corrosion. In the case of crevice, the metastable corrosion is easy to develop into stable one.     

Preparation,characterization and drug release behavior of poly(acrylic acid–co-2-hydroxyethyl methacrylate-co-2-acrylamido-2-methyl-1-propanesulfonic acid) microgels

In this paper, Poly(acrylic acid-co-2-hydroxyethyl methacrylate-co-2-acrylamido-2–methyl-1–propanesulfonic acid (AAc-HEMA-AMPS) microgels were synthesized by using an inverse suspension polymerization technique. The increase in the AMPS content of the microgels composition caused a large increase in water uptake. The morphology of the microgels was examined by environmental scanning electron microscopy (ESEM). The AMPS containing microgels had a mean particle diameter of 10 μm. The glass transition temperature of the microgels were examined by DSC and found that they show single Tg. Lidocaine (LD) and Methylene blue (MB) were used as model drugs for the investigation of drug release behavior of the microgels. Different drug release patterns were observed, for LD and MB loaded microgels. The release studies showed that some of the basic parameters affecting the drug release behavior of microgels were the specific and non-specific interactions between microgel and drug structure and pH of the dissolution medium. These hydrogels may be potential candidates for pH-sensitive applications.     

Electrical behavior of the Ruddlesden–Popper phase, (Nd0.9La0.1)2 Ni0.75Cu0.25O4 (NLNC) and NLNC- x wt% Sm0.2Ce0.8O1.9 (SDC) (x = 10, 30 and 50), as intermediate‐temperature solid oxide fuel cells cathode

In the present work, a new Ruddlesden-Popper phase, (Nd_0.9La_0.1)₂ Ni_0.75Cu_0.25O₄ (NLNC) has been synthesized by solid state reaction for intermediate-temperature solid oxide fuel cells (IT-SOFCs) applications. The effect of sintering temperature on the microstructure and electrical properties of the NLNC cathode material is investigated. Likewise, composite cathode materials were also prepared by mixing the NLNC with 10, 30 and 50 wt% of Sm_0.2Ce_0.8O_1.9 (SDC) powders, and firing in the temperature range of 1000–1300 °C. The crystal structure and chemical compatibility of NLNC and SDC, and their microstructures were studied by XRD and SEM, respectively. Electrical conductivity and performance of monolithic and composite electrodes as a function of the electrode composition is investigated experimentally through four probe method and electrochemical impedance spectroscopy (EIS). The results proved that no reaction occur between NLNC and SDC compounds even at a temperature as high as 1300 °C. Maximum total electrical conductivity of 114.36 S cm^?1 at 500 °C is recorded for the pure NLNC material sintered at 1300 °C. The polarization resistance of pure NLNC cathode was 0.43 Ω cm² at 800 °C; the NLNC–SDC composite cathodes including 10, 30 and 50 wt% SDC displayed Rp value of 0.27 Ω cm², 0.11 Ω cm², and 0.19 Ω cm² at 800 °C, respectively.