Transition metal silicides: fundamentals, preparation and catalytic applications

A study on the surface treatment of “Calmax” tool steel by a plasma transferred arc (PTA) process

Effects of parallel magnetic field on electrocodeposition behavior of Fe/nano-Si particles composite electroplating

Surface alloying of a commercially pure aluminium with nickel was carried out using a pulsed Nd-YAG laser. The distribution of the alloying element (nickel) in the alloyed layer was found to be highly non-uniform irrespective of the depth of alloying. The microstructure of the alloyed layer was found to consist mainly of a cellular solid solution phase of nickel in aluminium (α-Al), a lamellar eutectic of α-Al and Al 3 Ni phases, and primary Al 3 Ni dendrites. The microstructure of the alloyed layer is explained in terms of inhomogeneity of the nickel distribution. The effects on the microstructure of inherent rapid solidification under the conditions of laser surface alloying were also examined.

Evolution of microstructure in laser surface alloying of aluminium with nickel

This paper details the synthesis and combustion characteristics of silicon-based nanoenergetic formulations. Silicon nanostructured powder (with a wide variety of morphologies such as nanoparticles, nanowires, and nanotubes) were produced by DC plasma arc discharge route. These nanostructures were passivated with oxygen and hydrogen post-synthesis. Their structural, morphological, and vibrational properties were investigated using X-ray diffractometry, transmission electron microscopy (TEM), nitrogen adsorption-desorption analysis, Fourier transform infrared (FTIR) spectrometry and Raman spectroscopy. The silicon nanostructured powder (fuel) was mixed with varying amounts of sodium perchlorate (NaClO4) nanoparticles (oxidizer) to form nanoenergetic mixtures. The NaClO4 nanoparticles with a size distribution in the range of 5–40 nm were prepared using surfactant in a mixed solvent system. The combustion characteristics, namely (i) the combustion wave speed and (ii) the pressure-time characteristics, were measured. The observed correlation between the basic material properties and the measured combustion characteristics is presented. These silicon-based nanoenergetic formulations exhibit reduced sensitivity to electrostatic discharge (ESD).

Combustion Characteristics of Silicon-Based Nanoenergetic Formulations with Reduced Electrostatic Discharge Sensitivity

Armco iron was siliconized with two different gas mixtures in the temperature range of 750 to 1100 °C. The Ar-SiH4-H2 mixture leads mainly to the formation of a non-porous and adherent solid solution with a maximum silicon content of 6% by weight. For high concentrations of silane in the vapour phase or low treatment temperatures, non adherent pure silicon powder or flakey iron silicides may also depose. The use of Ar-SiH4-SiCl4-H2 mixture leads to the immediate nucleation of Fe3Si, the growth of which occurring from and around the open porosity of the coating. The influence of various parameters such as vapour phase composition and flow rate, hydrogen dilution and treatment temperature, is investigated and analysed in terms of limiting factors of the overall process: gas phase transport, interfacial reactions and diffusion velocity of different species in solid phase.

Chemical vapour deposition of silicon onto iron: influence of silicon vapour phase source on the composition and nature of the coating

The influence of a laser melting on both mechanical and electrochemical properties was studied in two carbon steels Geometry and microstructure of the melt zone were first observed by optical and scanning electron microscopy, in various experimental conditions: with different interaction times and power density, for simple and multiple track melting A large hardening was induced by the severe quenching resulting from rapid solidification; therefore the presence of hard points on the surface of the material may increase lifetime of specimens and improve tribological properties This hardening created by the laser melting did not produce deleterious modifications of surface roughness or corrosion behaviour, at least in mildly corrosive saline solutions

Laser surface melting of low and medium carbon steels: influence on mechanical and electrochemical properties

The microstructures and electrochemical behaviour of two types of laser surface alloys are compared. These surface alloys were obtained by melting a duplex coating made of two successive layers of nickel and chromium on a mild steel substrate. Two types of duplex coatings were used leading to FeNiCr or FeNiCrP surface alloys. Homogeneous, adherent and non-porous surface alloys were always obtained after laser treatment. The microstructures were dendritic in both cases with a high phosphorus segregation in the second type of treated samples. High corrosion resistance in neutral NaCl solution (0.5 M) was evidenced, using electrochemical techniques.

Microstructural characterization and comparative electrochemical behaviour of FeNiCr amd FeNiCrP laser surface alloys

The influence of the gaseous phase composition (SiH4 or SiCI4 diluted with argon or hydrogen), used for chemical vapor deposition of silicon onto two different substrates (pure iron or low chromium mild steel) is investigated. Depending on the chosen process, two types of coatings are developed: either a very adherent, non-porous solid solution containing up to 6 to 7 wt. % Si, or a Fe3Si iron silicide (14.35 wt. %). This solid solution coating considerably improves the oxidation resistance properties of steels at temperatures up to 800° C. This beneficial effect was not observed on the corrosion behavior of treated samples in sulfuric acid solutions. In contrast, the Fe3Si iron silicide has the same outstanding corrosion resistance that the silicon-rich cast alloys have in very severe environments such as boiling concentrated sulfuric acid. But this remarkable behavior is certainly limited in other mediums by the open porosity of the coating, inherent to the chemical vapor process.

Chemical vapor deposition of silicon onto iron and steel substrates: oxidation and corrosion properties of coated materials

/pdf/laser-surface-alloying-of-a-mild-steel-for-corrosion-4e32kaxv88.pdf

H. Mazille

Papers

Chemical vapour deposition of silicon onto iron: influence of silicon vapour phase source on the composition and nature of the coating

Laser surface melting of low and medium carbon steels: influence on mechanical and electrochemical properties

Microstructural characterization and comparative electrochemical behaviour of FeNiCr amd FeNiCrP laser surface alloys

Chemical vapor deposition of silicon onto iron and steel substrates: oxidation and corrosion properties of coated materials

Laser surface alloying of a mild steel for corrosion resistance improvement