|Posted by khcreations on March 10, 2009 at 8:30 PM||comments (0)|
|Posted by khcreations on March 10, 2009 at 8:28 PM||comments (0)|
|Posted by khcreations on February 14, 2009 at 12:55 AM||comments (0)|
In metallurgy, stainless steel is defined as a steel alloy with a minimum of 10% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel (it stains less), but it is not stain-proof. It is also called corrosion-resistant steel or CRES when the alloy type and grade are not detailed, particularly in the aviation industry. There are different grades and surface finishes of stainless steel to suit the environment to which the material will be subjected in its lifetime. Common uses of stainless steel are cutlery and watch straps.
Stainless steel differs from carbon steel by amount of chromium present. Carbon steel rusts when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by forming more iron oxide. Stainless steels have sufficient amount of chromium present so that a passive film of chromium oxide forms which prevents further surface corrosion and blocks corrosion spreading in the metal's internal structure.
|Posted by khcreations on February 13, 2009 at 12:49 AM||comments (0)|
On The Rise
...Nickel is a metal often present in certain jewelry components. Nearly 15% of the US population suffers from an allergy to nickel. This figure is up from 10% in the 80?s, due, it is believed, to the increased popularity of body piercing.
...People suffering from allergies to nickel have symptoms ranging from slight itching and redness of the skin to blisters at the area of contact. Actually, it is the nickel salts formed when the metal comes in contact with perspiration that cause the allergy. Once an allergy to nickel has been acquired, it is usually lifelong.
...This problem is so prevalent that, since January 2000, the European Union has imposed a nickel ban on all jewelry sold there. The European nickel free standard states that items labeled ?nickel free? may contain no more than 0.05% nickel (no more than 1 part in 2000 that is nickel.)
|Posted by khcreations on February 13, 2009 at 12:40 AM||comments (0)|
Sterling silver is an alloy of silver containing 92.5% pure silver and 7.5% other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
Fine silver (99.9% pure) is generally too soft for producing large functional objects; therefore, the silver is usually alloyed with either copper or titanium to give it strength, while at the same time preserving the ductility and beauty of the precious metal. Other metals can replace the copper, usually with the intent to improve various properties of the basic sterling alloy such as reducing casting porosity, eliminating firescale, and increasing resistance to tarnish. These replacement metals include germanium, zinc and platinum, as well as a variety of other additives, including silicon and boron. A number of alloys have appeared in recent years, formulated to lessen firescale or to inhibit tarnish, and this has sparked heavy competition among the various manufacturers, who are rushing to make claims of having the best formulation. However, no one alloy has emerged to replace copper as the industry standard, and alloy development is a very active area.