Influence of surface oxide characteristics and speciation on corrosion, electrochemical properties and metal release of atomized 316L stainless steel powders

Surface oxide characteristics of powder particles are important to consider for any toxicological risk assessment based on in-vitro or in-vivo tests. This study focuses on a multi-analytical approach (X-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning- and transmission electron microscopy, and different electrochemical techniques) for in-depth characterization of surface oxides of inert-gas-atomized (GA) AISI 316L stainless steel powder, compared with massive sheet and a water-atomized (WA) 316L powder. Implications of differences in surface oxide phases and their surface distribution on corrosion, electrochemical properties and metal release are systematically discussed. Cr was enriched in an inner surface layer for both GA powders, with Mn and S enriched in the outermost surface oxide. The surface oxide was 2-5 nm thick for both GA powder size fractions, amorphous for the GA powder size

Influence of surface oxide characteristics and speciation on corrosion, electrochemical properties and metal release of atomized 316L stainless steel powders

Surface oxide characteristics of powder particles are important to consider for any toxicological risk assessment based on in-vitro or in-vivo tests. This study focuses on a multi-analytical approach (X-ray photoelectron spectroscopy, Auger electron spectroscopy, scanning- and transmission electron microscopy, and different electrochemical techniques) for in-depth characterization of surface oxides of inert-gas-atomized (GA) AISI 316L stainless steel powder, compared with massive sheet and a water-atomized (WA) 316L powder. Implications of differences in surface oxide phases and their surface distribution on corrosion, electrochemical properties and metal release are systematically discussed. Cr was enriched in an inner surface layer for both GA powders, with Mn and S enriched in the outermost surface oxide. The surface oxide was 2-5 nm thick for both GA powder size fractions, amorphous for the GA powder size

Surface-protein interactions on different stainless steel grades: effects of protein adsorption, surface changes and metal release

Implantation using stainless steels (SS) is an example where an understanding of protein-induced metal release from SS is important when assessing potential toxicological risks. Here, the protein-induced metal release was investigated for austenitic (AISI 304, 310, and 316L), ferritic (AISI 430), and duplex (AISI 2205) grades in a phosphate buffered saline (PBS, pH 7.4) solution containing either bovine serum albumin (BSA) or lysozyme (LSZ). The results show that both BSA and LSZ induce a significant enrichment of chromium in the surface oxide of all stainless steel grades. Both proteins induced an enhanced extent of released iron, chromium, nickel and manganese, very significant in the case of BSA (up to 40-fold increase), whereas both proteins reduced the corrosion resistance of SS, with the reverse situation for iron metal (reduced corrosion rates and reduced metal release in the presence of proteins). A full monolayer coverage is necessary to induce the effects observed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10856-013-4859-8) contains supplementary material, which is available to authorized users

Release and stability of aluminum metal nanoparticles in surface water: effects of particle loading

При определении экотоксичности наночастиц важную роль играют условия пробоподготовки суспензий. В работе с помощью фотонной кросскорреляционной и атомной абсорбционной спектроскопии показано влияние концентрации суспензии (10 и 100 мг/л) на степень растворения и агрегацию электровзрывных наночастиц алюминия в растворе, моделирующем поверхностную воду пресного водоема

Welding fume nanoparticles from solid and flux-cored wires: Solubility, toxicity, and role of fluorides

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with solid wire reference fumes, which was associated with increased cytotoxicity and genotoxicity in-vitro. No crystalline Na or potassium (K) containing chromates were observed. Cr(VI) was incorporated in an amorphous mixed oxide. Solution-added fluorides did not increase the solubility of Cr(VI), but contributed to a reduced Mn release from both solid and flux-cored wire fume particles and the reduction of Cr(VI) release from solid wire fume particles. Chemical speciation modeling suggested that metal fluoride complexes were not formed. The presence of NaF in the welding electrodes did not have any direct, but possibly an indirect, role in the Cr(VI) solubility of welding fumes

XPS characterization of (copper-based) coloured stains formed on limestone surfaces of outdoor Roman monuments

Limestone basements holding bronzes or other copper alloys artefacts such as sculptures, decorations and dedicatory inscriptions are frequently met both in modern and ancient monuments. In outdoor conditions, such a combination implies the corrosion products of the copper based alloy, directly exposed to rainwater, will be drained off and migrate through the porous surfaces, forming stains of different colours and intensities, finally causing the limestone structures to deteriorate

Corrosion induced metal release from copper based alloys compared to their pure elements

Despite numerous studies on atmospheric corrosion of copper and copper based alloys, the corrosion induced release processes of individual alloy constituents suffer from significant knowledge gaps. This investigation comprises metal release rate measurements of copper, zinc and tin from some copper based alloys including brass (20 wt-%Zn) and bronze (6 wt-%Sn), and their pure alloying metals, copper, zinc and tin. Data have been generated during a 2,5 year urban field exposure in Stockholm, Sweden and parallel laboratory investigations in a specially designed rain chamber using artificial rain. Brass shows significantly lower annual release rates of both copper and zinc compared to pure metal sheets of its alloy constituents. Zinc is preferentially released compared to copper. Dezincification of brass occurs both at field and laboratory conditions, a process influenced by rain characteristics. Alloying with tin does not largely reduce the release rate of copper from bronze compared to pure copper. No measurable amount of tin is released from the bronze surface