The ‘Hazard classification and labelling’ section shows the hazards of a substance based on the standardised system of statements and pictograms established under the CLP (Classification Labelling and Packaging) Regulation. This information is only displayed if the substance is well-defined, its identity is not claimed confidential and there is sufficient information available in ECHA’s databases for ECHA’s algorithms to generate a molecular structure. If generated, an InChI string will also be generated and made available for searching. The molecular structure is based on structures generated from information available in ECHA’s databases. This information is only displayed if the substance is well–defined, its identity is not claimed confidential and there is sufficient information available in ECHA’s databases for ECHA’s algorithms to generate a molecular structure. The molecular formula identifies each type of element by its chemical symbol and identifies the number of atoms of each element found in one discrete molecule of the substance. More information about CAS and the CAS registry can be found here. A substance identified primarily by an EC or list number may be linked with more than one CAS number, or with CAS numbers that have been deleted. The CAS number is the substance numerical identifier assigned by the Chemical Abstracts Service, a division of the American Chemical Society, to substances registered in the CAS registry database. CAS (Chemical Abstract Service) registry number The EC or list number is the primary substance identifier used by ECHA. If the substance was not covered by the EC Inventory, ECHA attributes a list number in the same format, starting with the numbers 6, 7, 8 or 9. More information about the EC Inventory can be found here. The EC Inventory is a combination of three independent European lists of substances from the previous EU chemicals regulatory frameworks (EINECS, ELINCS and the NLP-list). The EC Number is the numerical identifier for substances in the EC Inventory. Some substance identifiers may have been claimed confidential, or may not have been provided, and therefore not be displayed. The substance identifiers displayed in the InfoCard are the best available substance name, EC number, CAS number and/or the molecular and structural formulas. (Other important metals such as titanium and aluminum also rely on passive film formation for their corrosion resistance.) Because of its durability and aesthetic appeal, stainless steel is used in a wide variety of products, ranging from eating utensils to bank vaults to kitchen sinks.The ‘Substance identity’ section is calculated from substance identification information from all ECHA databases. In summary, stainless steel does not rust because it is sufficiently reactive to protect itself from further attack by forming a passive corrosion product layer. As such, this film, otherwise known as rust, achieves sufficient thickness to make it easily observable soon after exposure to water and air. Common inexpensive steel, in contrast, reacts with oxygen from water to form a relatively unstable iron oxide/hydroxide film that continues to grow with time and exposure to water and air. Thus, although the steel is corroded on the atomic level, it appears stainless. The fact that the film is much thinner than the wavelength of light makes it difficult to see without the aid of modern instruments. Because the film forms so readily and tightly, even only a few atomic layers reduce the rate of corrosion to very low levels. The presence of the stable film prevents additional corrosion by acting as a barrier that limits oxygen and water access to the underlying metal surface. In fact, all stainless steels by definition contain at least 10 percent chromium. Chromium plays a dominant role in reacting with oxygen to form this corrosion product film. These elements react with oxygen from water and air to form a very thin, stable film that consists of such corrosion products as metal oxides and hydroxides. Stainless steel contains iron, chromium, manganese, silicon, carbon and, in many cases, significant amounts of nickel and molybdenum. Stainless steel remains stainless, or does not rust, because of the interaction between its alloying elements and the environment. Free of the University of Utah offers this explanation:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |