酸化アルミニウムの式は？

Many industries rely on aluminum oxide, but few know what it really is. Understanding its formula unlocks its power in manufacturing and product design.

The chemical formula for aluminum oxide is Al₂O₃, representing two aluminum atoms bonded with three oxygen atoms.

This simple formula stands behind a wide range of high-performance materials and applications—from electronics to abrasives.

How is aluminum oxide chemically represented?

Chemistry might seem abstract, but knowing formulas helps in practical ways—especially in sourcing or evaluating materials.

Aluminum oxide is represented by the formula Al₂O₃, indicating that each molecule contains two aluminum (Al) atoms and three oxygen (O) atoms.

Understanding the Bond

Aluminum has a valency of +3. Oxygen has -2. To form a stable compound, two Al³⁺ ions bond with three O²⁻ ions. The result is Al₂O₃—a neutral, stable compound.

Here’s a breakdown of the charge balance:

Ion	Charge	Count	Total Charge
Al³⁺	+3	2	+6
O²⁻	-2	3	-6
Sum			0 (neutral)

This chemical stability explains why aluminum oxide is so resistant to corrosion and chemical breakdown.

Crystal Structure

Aluminum oxide commonly appears in two forms:

• Alpha-Al₂O₃ (corundum): Hard, crystalline, used in abrasives.
• Gamma-Al₂O₃: Porous, used in catalysis.

Though the formula stays the same, the physical form changes based on heat treatment and application.

Why is aluminum oxide formula important in products?

Materials aren’t just chosen for appearance—they’re chosen for chemical properties.

The formula Al₂O₃ determines aluminum oxide’s physical and chemical traits, making it essential in selecting it for abrasion, insulation, or catalyst roles.

High Melting Point

Because of its strong ionic bonds, Al₂O₃ has a melting point over 2000°C. That’s why it’s used in:

• Furnace linings
• High-temperature insulation
• Ceramics

電気絶縁

Despite being made from a metal, Al₂O₃ doesn’t conduct electricity. This makes it ideal for:

• Circuit board substrates
• Electronic packaging
• Spark plug insulators

Chemical Inertness

It resists acids and bases, which means:

• 腐食なし
• Long life in harsh environments
• Safe for use in medical and food-grade tools

プロパティ	結果	Industrial Impact
High Hardness	Scratch-resistant	Abrasives, wear parts
熱安定性	Resists heat >2000°C	Kilns, crucibles
Electrical Resist	非導電性	Electronics, power modules
Chemical Stable	非反応性	Medical and filtration systems

Does formula differ for hydrated forms?

We often see “aluminum oxide” in products, but some contain water. Is that still Al₂O₃?

Yes, hydrated forms of aluminum oxide have modified formulas, such as Al(OH)₃ or AlO(OH), which include water or hydroxide groups alongside the base Al₂O₃ structure.

Common Hydrated Forms

There are three main types:

• Bauxite (raw ore): Mostly Al(OH)₃
• Boehmite: AlO(OH)
• Gibbsite: Al(OH)₃

These compounds contain water, either loosely bound or as hydroxide ions. When heated, they lose water and convert to pure Al₂O₃.

Dehydration Process

Industries often heat these hydrated forms to 1000°C+ to extract pure Al₂O₃. This is part of the Bayer Process used in aluminum production.

なぜ重要なのか

If you’re choosing a material for high-temperature applications, make sure it’s fully converted to Al₂O₃. Hydrated forms can’t handle heat or chemical exposure as well.

Form	Formula	Water Content	申し込み
Gibbsite	Al(OH)₃	高い	Raw material for Al₂O₃
Boehmite	AlO(OH)	ミディアム	Ceramics, catalysis
Aluminum Oxide	Al₂O₃	なし	Abrasives, refractories

Where is aluminum oxide commonly used?

Aluminum oxide appears everywhere—even if you don’t see it.

Aluminum oxide is used in abrasives, electronics, ceramics, coatings, and even dental materials due to its hardness, thermal resistance, and inertness.

産業用途

• Abrasives: Sandpaper, grinding wheels
• Refractories: Furnace linings
• Ceramics: Labware, filters
• エレクトロニクス: Insulators, chip substrates

消費者製品

• Toothpaste: Mild abrasive
• Cosmetics: Polish agent
• コーティング: Anti-scratch layers

Medical and Aerospace

Because it doesn’t react with body fluids, Al₂O₃ is used in:

• Bone implants
• Dental crowns
• Aircraft parts

Here’s a quick reference:

セクター	ユースケース	ベネフィット
製造業	Abrasive belts, cutting tools	Hardness, durability
エレクトロニクス	Substrate, insulator	Electrical resistance
ヘルスケア	Dental tools, implants	Biocompatibility, non-reactive
自動車	Brake pads, spark plugs	Heat resistance, strength

結論

Aluminum oxide’s formula—Al₂O₃—holds the key to its many uses. Its simple chemistry translates into powerful performance across industries. Whether pure or hydrated, its structure delivers strength, insulation, and resilience.