Coatings for corrosion protection of porous substrates in gasifier components

Deposition of several coatings by Chemical Vapor Deposition in a Fluidized Bed was studied inside porous coupons made of 409 steel. Four different coating systems were studied: TiAlSiN/TiAl/SS409, TiAlSiN/TiAlSi/SS409, TiAlN/Nb/TiAl/SS409 and TiSiN/Nb/TiSi/SS409. Though coating thickness decreased with depth inside the porous filter, the formation of Ti-based ceramic films with thicknesses around 1 micrometer was observed 0.5 mm inside the bulk of the samples. Coated substrates were exposed to a simulated coal gas at 643 K for 300 hours, in order to study their corrosion resistance under conditions that mimic a porous metal particulate filter of a coal gasification system. Some of the coatings did not provide enough protection against corrosion at the bulk of the porous coupons, and iron sulfide crystals were formed that plugged the pores. On the other hand, the TiSiN/Nb/TiSi/SS409 system showed no sign of corrosion.     

Shielding Effects in Thin-Film Integrated Circuits

The shielding effect of a thin (or thick) film ground plane on two film conductors has been theoretically investigated by viewing the problem as that of determining the scattering matrix coefficients of a microstrip directional coupler in terms of various transmission-line parameters. The effect of resistive losses in the film conductors and ground plane are considered and methods of systematically determining all transmission parameters have been evolved. Recently published equations for the design of coupled microstrips are used to determine pertinent transmission-line parameters. These results can serve as a guide to designers of thin-film integrated circuits, wherein undesired coupling levels can be predicted and optimum circuit layouts can be determined.     

Simulation of Multi-Element Antenna Systems for Navigation Applications

The application of user terminals with multiple antenna inputs for use with the global navigation satellite systems like Global Positioning System (GPS) and Galileo has attracted more and more attention in the past years. Multiple antennas may be spread over the user platform and provide signals required for the platform attitude estimation or may be arranged in an antenna array to be used together with array processing algorithms for improving signal reception, e.g., for multi-path and interference mitigation. In order to generate signals for testing of receivers with multiple antenna inputs and corresponding receiver algorithms in a laboratory environment, a unique hardware signal simulation tool for wavefront simulation has been developed. The signals for a number of antenna elements are first generated in a flexible user defined geometry as digital signals in baseband and then mixed up to individual RF-outputs. This paper describes the principle functionality of the system and addresses some calibration issues. Measurement setups and results of data processing with simulated signals for different applications are shown and discussed.