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Carzin coatings. Harder than Diamond |
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Diamond-like carbon (DLC) is any of seven forms[1] of amorphous carbon materials that display some of the unique properties of natural diamond. They are usually applied as coatings to other materials that could benefit from some of those properties. All seven contain significant amounts of sp3 hybridized carbon atoms. The reason that there are different types is that even natural diamond can be found in two crystalline polytypes. The usual one has its carbon atoms arranged in a cubic lattice, while the very rare one (lonsdaleite) has a hexagonal lattice. By mixing these polytypes in various ways at the nanoscale level of structure, DLC coatings can be made that at the same time are amorphous, flexible, and yet purely sp3 bonded "diamond". The hardest, strongest, and slickest is such a mixture, known as tetrahedral amorphous carbon, or ta-C. For example a coating of only 2μm thickness of ta-C increases the resistance of common (i.e. type 304) stainless steel against abrasive wear; changing its lifetime in such service from one week to 85 years. Such ta-C can be considered to be the "pure" form of DLC, since it consists only of sp3 bonded carbon atoms. Fillers such as hydrogen, graphitic sp2 carbon, and metals are used in the other 6 forms to reduce production expenses, but at the cost of decreasing the service lifetimes of the articles being coated. The various forms of DLC can be applied to almost any material that is compatible with a vacuum environment. |
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Technical Specifications |
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The strongest, and slickest form of DLC, it is known as tetrahedral amorphous carbon, or ta-C |
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Technical Details |
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Protective coatings can be made from 7 known types of hard carbons. Each type has some of the properties of diamond. The different types are made by loading the materials with hydrogen and graphite fillers. The more loading, the less content of the diamond part called (sp3).Engineering standards agencies plot maps for all types of these coatings using hydrogen (H) content (bad) and (sp3) content (good) as the equivalent GPS locations for quality.
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