prov:value
| - boron, cobalt, beryllium, zinc, and tin, metal alloys such as steel, brass, bronze, boron carbide whiskers, and tungsten carbide whiskers, metal oxides such as zinc oxide, iron oxide, aluminum oxide, titanium oxide, magnesium oxide, and zirconium oxide, particulate carbonaceous materials such as graphite, carbon black, cotton flock, natural bitumen, cellulose flock, and leather fiber, micro balloo
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