Plasma Electrolytic Oxidation of Arc-Sprayed Aluminum Coatings

Different posttreatment methods, such as heat treatment, mechanical processing, sealing, etc., are known to be capable to improve microstructure and exploitation properties of thermal spray coatings. In this work, a plasma electrolytic oxidation of aluminum coatings obtained by arc spraying on aluminum and carbon steel substrates is carried out. Microstructure and properties of oxidized layers formed on sprayed coating as well as on bulk material are investigated. Oxidation is performed in electrolyte containing KOH and liquid glass under different process parameters. It is shown that thick uniform oxidized layers can be formed on arc-sprayed aluminum coatings as well as on solid material. Distribution of alloying elements and phase composition of obtained layers are investigated. A significant improvement of wear resistance of treated layers in two types of abrasive wear conditions is observed. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.     

Numerical Modeling of Grain Boundary Effects in the Diffusional Creep of Copper Interconnect Lines

We propose a numerical simulation technique to model the process of diffusional creep and stress relaxation that occurs in Cu-damascene interconnects of integrated circuit devices in processing stage. The mass flow problem is coupled to the stress analysis through vacancy flux and equilibrium vacancy concentration. The technique is implemented in a software package that seamlessly integrates the problem-oriented code with commercially available finite element program MSC.Marc. It is utilized to model the Coble creep phenomenon by introducing the nanoscale grain boundary region having the thickness on the order of several layers of atoms. As an illustration, the two-dimensional problem of stress relaxation in a single grain subjected to prescribed displacements and tractions is examined.     

Formation of palladium nanoparticles under pulse current in a dimethylformamide solution

The morphology of palladium deposited by pulse electrolysis from dimethylformamide solutions of PdCl₂ on the surface of graphite and ITO glass was studied. The effect of the value of cathode potential and electrolysis duration on the sizes of particles and their distribution in the substrate was investigated. It was shown that, on the substrate surface, deposits with particle sizes of 30–350 nm are formed.     

Fatigue properties of carbon steels chromized by a diffusion treatment under various conditions

A study was carried out on the effect of the variation in a gaseous diffusion chromizing treatment conditions on the fatigue properties of chromized carbon steels tested in the elastic and elasto-plastic strain range in air and certain aggressive media. An explanation is given of the dependence of the fatigue and corrosion-fatigue strength on the thickness of chromized layers and on the method of their preparation.     

Endurance of steels and alloys case-hardened by diffusion treatments

Data illustrating the effect of aliting, bonding and chromizing on the fatigue strength of structural steels in working media are presented, and an explanation is given of changes in the fatigue and corrosion-fatigue strength of steel depending on its structure and stress state.     

Corrosion of High-Strength Cr–Mn Steels in Chloride Solutions

High-nitrogen Cr-Mn steels 12X18A18 and 05X18A19 are attacked by pitting in NaCl solutions at > 0.1 g-ion/l and T > 313 K because the protective properties of their passive surface films deteriorate (their resistance decreases by a factor of three to six). The passivity range of these steels narrows to 87 and 90 mV at their corrosion depth indices of 1.2 × 10^–3 and 8 × 10^–4 mm/year, respectively. Pitting of 60X38H8B Cr-Mn-Ni steel exposed to NaCl solutions was observed at > 0.3 g-ion/l and T > 303 K. Its corrosion depth index increases to 1.48 mm/year. At < 0.1 g-ion/l, all the steels studied are highly resistant to corrosion.