Search

The single layers of TiN, TiAlN and TiN/TiAlN multilayer coatings were deposited on 316L SS bipolar plate by physical vapor deposition technique. The X-ray diffraction studies revealed that the formed coatings exhibited single-phase cubic structure. The low surface roughness and high contact angles of the TiAlN and TiN/TiAlN coatings governed the better water management in the fuel cell. Nyquist and Bode-impedance studies of TiN/TiAlN coating ensured higher electrochemical impedance behavior. The polarization results revealed that the current densities (icorr) of TiN/TiAlN coating were below 1 µA/cm2 in the PEMFC environments, which satisfied the U.S. Department of Energy's 2020 target. The contact resistance of the TiN/TiAlN-coated 316L SS was the lowest and fulfilled the requirements of bipolar plate (≤ 10 mΩ cm2) in PEMFC environment. Surface morphology results revealed that the surface of 316L SS is well protected by multilayer TiN/TiAlN coating. Inductive coupled plasma-optical emission spectroscopy results are in good agreement with electrochemical studies revealing the TiN/TiAlN coating significantly reduced the metal ions dissolution. [ABSTRACT FROM AUTHOR]

Mechanical and thermal properties of poly(arylene disulfide) synthesized by ring-opening reaction of cyclic(aromatic disulfide) oligomer were reported. These oligomers were prepared from 4,4′-oxybis(benzenethiol). Three-point bending tests were performed to measure the flexural properties of the poly(arylene disulfide). DSC and TGA techniques were used to characterize the thermal properties of these polymers. Ring-opening reactions were carried out by hot-press under atmosphere and nitrogen atmosphere, respectively. Oxidation reaction of these polymers was detected from Raman spectra under atmosphere. The glass transition temperature increased but 10% weight loss temperature decreased with increasing ring-opening temperature. The flexural strength decreased with increasing the temperature of ring-opening polymerization under both atmosphere and nitrogen atmosphere. The polydisulfides could be used as high temperature and thermally curing insulating materials to substitute epoxy resins. [ABSTRACT FROM AUTHOR]

Poly(arylene disulfide)s were prepared by thermo-initialized ring-opening polymerization (ROP) of macrocyclic(arylene disulfide) oligomers. These macrocyclic oligomers were synthesized by catalytic oxidation of 4,4'-oxybis(benzenethiol) with oxygen in the presence of a copper-amine catalyst. This is the first work to characterize and investigate the electrical and mechanical properties of the poly(arylene disulfide)s obtained via ring-opening polymerization. The surface resistance and volume resistance of the polyaromatic disulfides cured at 180-220°C were higher than 1014 ohm and 1016 ohm·cm, respectively. The results indicated that the as-made polymers exhibited superior dielectric properties. Both mechanical strength and electrical properties of these polymers varied according to ROP conditions. These properties demonstrated that the macrocyclic(arylene disulfide) oligomers derived from 4,4'-oxybis(benzenethiol) could be used to produce thermally curing insulating material to substitute epoxy resins. [ABSTRACT FROM AUTHOR]