Hard coat aluminum anodizing is the same composition as decorative aluminum anodizing, just thicker. It is actually a surface conversion to a ceramic (aluminum oxide). Believe it or not it is harder than hardened steel and very wear resistant to sliding wear. The only problem is that since it is only a few thousandths of an inch thick it is easily scratched if anything digs into the coating, breaking through the hardcoat and into the soft aluminum underneath.