Aluminium oxide, AI₂O₃, is a metallic oxide used in powdery form as raw material for a closed-pore, fine-grained, brittle and wear-resistant sintering material. Mixed with binding agents and – depending on the desired degree of purity – with other metallic oxides, the AI₂O₃ powder is compressed into machinable green compacts. High strength is achieved by sintering at 1600 to 1750° C. Material characteristics materials for seal faces and stationary seats. Paired with the various carbon seal faces aluminium oxide forms one of the face material pairings with the highest resistance to corrosion. Its porosity and resultant high wear make it unsuitable, however, for pressures >25 bar.