2818.10 - Artificial corundum, whether or not chemically defined:

This HTS category, 2818.10, specifically addresses "Artificial corundum, whether or not chemically defined." Artificial corundum is a manufactured abrasive material primarily composed of aluminum oxide (alumina), produced through high-temperature processes. It is valued for its extreme hardness and is used in a wide range of industrial applications, including grinding wheels, sandpaper, polishing compounds, and as a refractory material. The "whether or not chemically defined" clause indicates that the classification applies regardless of the purity or precise chemical composition, as long as the material exhibits the characteristic properties of artificial corundum.

It is important to distinguish this category from its siblings. HTS 2818.20.00.00 covers "Aluminum oxide, other than artificial corundum," which typically refers to aluminum oxide in its less processed forms or for different applications. Similarly, HTS 2818.30.00.00 classifies "Aluminum hydroxide," a distinct chemical compound and precursor material not possessing the hardened, crystalline structure characteristic of corundum.

Within 2818.10, further subdivisions differentiate based on the physical form and processing of the artificial corundum. The subcategory 2818.10.10.00 covers "Crude" artificial corundum, generally meaning the material as it is initially formed before significant processing. In contrast, 2818.10.20 encompasses artificial corundum that has been further processed into "grains, or ground, pulverized or refined." This distinction is crucial for classification as it reflects the level of industrial preparation and intended use of the material.