Search results for "CORROSION"
showing 6 items of 456 documents
Statistical prediction of corrosion front penetration
1997
A statistical method to predict the stochastic evolution of corrosion fronts has been developed. The method is based on recording material loss and maximum front depth. In this paper we introduce the method and test its applicability. In the absence of experimental data we use simulation data from a three-dimensional corrosion model for this test. The corrosion model simulates localized breakdown of a protective oxide layer, hydrolysis of corrosion product and repassivation of the exposed surface. In the long time limit of the model, pits tend to coalesce. For different model parameters the model reproduces corrosion patterns observed in experiment. The statistical prediction method is base…
Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions
2021
The biodegradable metals, including magnesium (Mg), are a convenient alternative to permanent metals but fast uncontrolled corrosion limited wide clinical application. Formation of a barrier coating on Mg alloys could be a successful strategy for the production of a stable external layer that prevents fast corrosion. Our research was aimed to develop an Mg stable oxide coating using plasma electrolytic oxidation (PEO) in silicate-based solutions. 99.9% pure Mg alloy was anodized in electrolytes contained mixtures of sodium silicate and sodium fluoride, calcium hydroxide and sodium hydroxide. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle (CA), …
Conditioning metallic aluminum in magnesium phosphate cements
2016
This work deals with the stabilization / solidification of radioactive waste using cement.More particularly, it aims at assessing the chemical compatibility between metallic aluminum and mortars based on magnesium phosphate cement. The physical and chemical processes leading to setting and hardening of the cement are first investigated. X-ray diffraction (XRD), thermogravimetry (TGA) and nuclear magnetic resonance spectroscopy (31P and11B MAS-NMR) arefirst used to characterize the solid phases formed during hydration, while inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES), electrical conductimetry and pH measurementsprovide information on the pore solution composit…
Preliminary study on the laser cleaning of stainless steels after high temperature oxidation
2000
Abstract The objective of the present work was to estimate the influence of pulsed laser irradiation on the removal of the oxide layer, which is developed on the surface of stainless steels during their exposure to high temperature oxidation. In general, this layer is a protective one, mainly against corrosion. However, in many manufacturing applications or maintenance work, the removal of the oxides is necessary; for example, the metallic surfaces should be cleaned before welding, otherwise the presence of oxides increases the tendency to brittle behaviour of the joint. In this study, a pulsed Nd:YAG laser (λ=1.064 μm, 10 ns) was used for the surface cleaning of three stainless steels with…
An assembly of organic-inorganic composites using halloysite clay nanotubes
2018
Halloysite is natural tubular clay suitable as a component of biocompatible nanosystems with specific functionalities. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting supramolecular and covalent interactions resulting in controlled colloidal stability adjusted to the solvent polarity. The functionalized halloysite nanotubes can be employed as reinforcing filler for polymers as well as carriers for the sustained release of active molecules, such as antioxidants, flame-retardants, corrosion inhibitors, biocides and drugs. The tubular morphology makes halloysite a perspective template for core-shell metal supports for mesoporous catalysts. The cataly…
Macroscopic and local electrochemical studies of austempered ductile iron in perchlorate solutions.
2006
The corrosion behavior of austempered ductile iron (ADI) in alkaline environment has been investigated at the microscale by means of the electrochemical microcell technique, surface analysis methods, and at the macroscale using classical electrochemical techniques. Local electrochemical investigations have revealed that the matrix (ausferrite), far from spheres, undergoes passivation in 1 M NaClO 4 , pH 10 solution within a wide potential range, from the corrosion potential (of about -280 mV/SCE) until 800 mV/SCE. Surface observations combined with local electrochemical analysis have shown that corrosion of ADI first occurs in the close vicinity of some graphite spheres and then around oxid…