Post by L Roebuck on Jan 20, 2006 8:51:19 GMT -5
This is an interesting article but just too long to post it on the forum.
Modern Methods of Particle Characterization – Supplier Data By Micromeritics
Background
Since prehistory man has been aware of the importance of particle size in producing resources and wares with desired properties. Archeological evidence indicates that paints used for cave wall paintings are mixtures of finely pulverized pigmenting materials, predominantly carbon, ochre and hematite. Man came to realize that adding pulverized materials to clay not only improved its workability, but improved the drying process, reduced shrinkage and changed the characteristics of the resulting vessels. There also is evidence of using particles of certain sizes to control porosity.
For many centuries, finely divided, calcined lime powder or gypsum mixed with sand was used in plasters and binders. Then, about 2000 years ago, the Romans improved upon the formula by adding volcanic (pozzolanic) ash, which produced a superior hydraulic cement that was used in building many structures that still stand.
Today, finely divided particulate materials and objects that incorporate or are produced from these fine particles are everywhere about us. Frequently encountered powders include cement, lime, fertilizer, cosmetic powders, table salt and sugar, detergents, bath and dental powders, coffee creamer, baking soda, and many other household items. Products in which the incorporation of powders is not so obvious include paint, toothpaste, lipstick, mascara, chewing gum, magnetic recording media, many medicinal products, slick magazine covers, floor coverings, and automobile tires.
Such everyday items as fused ceramic bathroom fixtures and many small metal objects produced by powder metallurgy completely obscure their origins as powders. The gold trim of dinnerware, for example, started as a carefully controlled fine powder. Even microwave cooking utilizes particle technology. The desire to brown some foods cooked by microwave was solved by a wrapping of metalized polyethylene terephthalate (PET) film, a material containing fine grained metallic material that absorbs microwaves and produces localized elevated temperatures.
www.azonano.com/Details.asp?ArticleID=1480
Modern Methods of Particle Characterization – Supplier Data By Micromeritics
Background
Since prehistory man has been aware of the importance of particle size in producing resources and wares with desired properties. Archeological evidence indicates that paints used for cave wall paintings are mixtures of finely pulverized pigmenting materials, predominantly carbon, ochre and hematite. Man came to realize that adding pulverized materials to clay not only improved its workability, but improved the drying process, reduced shrinkage and changed the characteristics of the resulting vessels. There also is evidence of using particles of certain sizes to control porosity.
For many centuries, finely divided, calcined lime powder or gypsum mixed with sand was used in plasters and binders. Then, about 2000 years ago, the Romans improved upon the formula by adding volcanic (pozzolanic) ash, which produced a superior hydraulic cement that was used in building many structures that still stand.
Today, finely divided particulate materials and objects that incorporate or are produced from these fine particles are everywhere about us. Frequently encountered powders include cement, lime, fertilizer, cosmetic powders, table salt and sugar, detergents, bath and dental powders, coffee creamer, baking soda, and many other household items. Products in which the incorporation of powders is not so obvious include paint, toothpaste, lipstick, mascara, chewing gum, magnetic recording media, many medicinal products, slick magazine covers, floor coverings, and automobile tires.
Such everyday items as fused ceramic bathroom fixtures and many small metal objects produced by powder metallurgy completely obscure their origins as powders. The gold trim of dinnerware, for example, started as a carefully controlled fine powder. Even microwave cooking utilizes particle technology. The desire to brown some foods cooked by microwave was solved by a wrapping of metalized polyethylene terephthalate (PET) film, a material containing fine grained metallic material that absorbs microwaves and produces localized elevated temperatures.
www.azonano.com/Details.asp?ArticleID=1480