Aluminum oxide (Al2O3, CAS 1344-28-1) is a versatile inorganic compound existing in several polymorphs, most commonly alpha-alumina (corundum) and gamma-alumina. It is a hard, amphoteric oxide with high thermal stability and electrical insulation properties. Its primary applications are in materials science and industrial chemistry. As a precursor, it is used to produce advanced ceramics, abrasives, and refractory materials. In its high-surface-area gamma form, it serves as a catalyst support and an adsorbent. Additionally, it is widely employed as a functional filler in coatings and polymers to enhance hardness, scratch resistance, and thermal conductivity, and as a polishing agent for metals and optics. Due to its chemical inertness and hardness, Al2O3 is also a common component in protective and anti-wear coatings. While it has niche uses in pharmaceuticals as an adjuvant or antacid, its dominant role is as a fundamental material chemical, not a pharmaceutical intermediate.