The corrosion behavior of hard W–C system chemical vapor deposition layers in HCl and H<Subscript>2</Subscript>S aqueous solutions

The results of a study of anticorrosion performance of low carbon containing tungsten-based hard chemical vapor deposition (CVD) coatings with microhardness from 5 to 17 GPa are presented in this work. Their high corrosion resistance in hydrochloric acid and hydrogen sulfide solutions is noted, as their corrosion rate does not exceed 6 μm per year in hydrochloric acid solution and 15 μm per year in hydrochloric acid solution saturated with hydrogen. The open circuit potentials correspond to tungsten (VI) oxide formation so the corrosion process supposedly runs in passive state. Taking into account the low porosity of the CVD layers, which is lower than 0.02%, these coatings are promising for application as anticorrosion wear-resistant coatings for chemical and oil and gas apparatus responsible units.     

Synthesis of Liquid Crystalline Organometallic Poly(arylene)s Containing 1,3-Type (η4-Cyclobutadiene)cobalt Moieties in the Main Chain

Novel organometallic poly(arylene)s containing 1,3-type (cyclobutadiene)cobalt moieties in the main chain were prepared by the Ni(0)-mediated dehalogenative polycondensation of monomers having (cyclobutadiene)cobalt moieties. The resulting poly(arylene)s were partly soluble in organic solvents and the number-average molecular weights (M _n) of soluble fractions were estimated to be 16,700–22,000 by GPC. The polymers showed the formation of a -conjugated structure, good solubility in common organic solvents, and thermotropic liquid crystallinity.     

Simulation of the electrical properties of polycrystalline ceramic semiconductors with submicrometer grain sizes

A numerical model for the calculation of the electrical characteristics of polycrystalline ceramic semiconductors is suggested. The model is applicable in a situation where the average grain size is comparable with the depletion region width near a grain boundary and the double Schottky barriers of neighboring boundaries overlap. The two-dimensional calculation is carried out in the diffusion-drift approximation using the Voronoi grid method. The effect of crystalline grain size on the current-voltage characteristic and specific capacitance of the material is analyzed usingp-SrTiO₃ as an example.     

Mechanical Properties and Corrosion Resistance of Hard β-W based CVD Coatings in Aqueous NaCl Solution

Protection of Metals and Physical Chemistry of Surfaces - The paper presents the results of studying the mechanical and anticorrosive properties of coatings based on the metastable tungsten phase...