Aluminum-silicon coatings on austenitic stainless steel (AISI 304 and 317) deposited by chemical vapor deposition in a fluidized bed

Abstract

Aluminum-silicon coatings were deposited onto stainless steels AISI 304 and AISI 317. The deposition was performed at 540°C with a ratio of active gases HCl/H2 of 1/15.3; argon was used as a carrier gas. The bed of the FBR-CVD process consisted of 2.5 g aluminum powder, 7.5 g silicon powder and 90 g alumina. After the coatings were deposited, each sample was given a heat treatment to improve its mechanical properties and oxidation behavior by diffusing the alloying elements. Thermodynamic simulation was performed with Thermo-Calc software to investigate the composition of the deposited material. The coated and uncoated specimens were exposed to temperatures of 750 ºC in an atmosphere where the vapor was transported to the samples using a flow of N2 of 40 ml/min and 100% water vapor (H2O). The coated specimens gained little weight during the thousand hours of exposure and will thus guard against a corrosive attack compared to the uncoated substrates. In addition, the coated stainless steels show an oxidation rate with a logarithmic trend while the uncoated steel oxidation rate showed a linear trend.Keywords: Coating, aluminum-silicon, chemical vapor deposition, high temperature oxidation, stainless steel, oxidation rate, steam oxidation. RESUMENSe obtuvieron recubrimientos de aluminio-silicio en los aceros inoxidables AISI 304 y AISI 317. La deposición se realizó a 540 °C, con una proporción de gases activos (HCl/H2: 1/15.3), como gas de arrastre se utilizó argón. El lecho del proceso CVD-FBR estaba formado por 2,5 g de polvo de aluminio, 7,5 g polvo de silicio y 90 g de alúmina. Después de depositados los recubrimientos, se le dio un tratamiento térmico para mejorar sus propiedades mecánicas y su comportamiento frente a la oxidación, por entre la difusión de los elementos de aleación. La simulación termodinámica se realizó con el software Thermo-Calc para obtener información sobre la posible composición del material depositado. Las muestras recubiertas y sin recubrir, se expusieron a 750 ºC en una atmósfera donde el vapor se transporta a las muestras usando un flujo de N2 de 40 ml / min y 100% de vapor de agua (H2O). Aceros recubiertos ganaron algo de peso durante las mil horas de exposición y resisten muy bien el ataque corrosivo frente a los sustratos recubiertos. Además, los aceros inoxidables recubiertos muestran una velocidad de oxidación con tendencia logarítmica, mientras que la velocidad de oxidación de acero sin recubrimiento tiene tendencia lineal.Palabras clave: Recubrimiento, Aluminio/Silicio, Deposición Química de Vapor, Oxidación a Alta temperatura, acero inoxidable, velocidad de oxidación, oxidación en vapor.

Miniaturized Inductive LC Pressure Sensor

“…Compared to solenoids, planar coils have better flexibility, low volume occupancy, and can be easily manufactured [74], [75]. The coil design is an air coil made of a copper or aluminum material which will then be integrated into silicon to prevent further oxidation of the coils whilst in the body, further extending its shelf life [76]. The initial 3 outer parameters used for this design are 3000 µm x 3000 µm x 0.5 µm (Model A), 2000 µm x 2000 µm x 0.5 µm (Model B), and 1000 µm x 1000 µm x 0.5 µm (Model C).…”

Miniaturized Inductive LC Pressure Sensor

“…Compared to solenoids, planar coils have better flexibility, low volume occupancy, and can be easily manufactured [74], [75]. The coil design is an air coil made of a copper or aluminum material which will then be integrated into silicon to prevent further oxidation of the coils whilst in the body, further extending its shelf life [76]. The initial 3 outer parameters used for this design are 3000 µm x 3000 µm x 0.5 µm (Model A), 2000 µm x 2000 µm x 0.5 µm (Model B), and 1000 µm x 1000 µm x 0.5 µm (Model C).…”