99 Alumina Bolts vs. Metal Bolts: Why the Radical Choice Difference

As fundamental fasteners, the material selection of bolts directly impacts performance and safety. The differences between 99% alumina bolts (referring to ceramic bolts with an alumina purity of over 99%) and metal bolts stem from the inherent disparities in their atomic structures and chemical bonds.

1. Core Property Comparison

99% alumina bolts are bonded by ionic and covalent bonds, while metal bolts are primarily joined by metallic bonds. This structural difference endows alumina bolts with extremely high hardness (Mohs hardness 9, second only to diamond), excellent wear and corrosion resistance (resistant to strong acids and alkalis), as well as electrical insulation and high-temperature tolerance (sustained service temperature exceeding 1500°C). However, they exhibit significant brittleness and poor impact resistance.

In contrast, metal bolts boast good ductility, strong impact resistance, and superior electrical and thermal conductivity. Yet they have relatively low hardness, are prone to corrosion (stainless steel excepted), and tend to soften at high temperatures.

2. Application Scenario Differentiation

99% alumina bolts are engineered for extreme environments:

Semiconductor equipment: No metal contamination, electrical insulation

High-temperature kilns: Heat resistance without deformation

Strongly corrosive settings: Chemical reactors, medical devices

High-precision instruments: Non-magnetic, low thermal expansion

Metal bolts cater to general-purpose requirements:

Construction & bridges: High-toughness load-bearing

Mechanical equipment: Vibration and fatigue resistance

Daily maintenance: Low cost, easy processing

3. Key Usage Notes

Material selection must balance performance and limitations. Installation of alumina bolts requires precautions against brittle fracture to avoid localized stress concentration. For metal bolts used in humid or corrosive environments, surface treatment (e.g., galvanization) is necessary. In terms of cost, 99% alumina bolts are typically 5–10 times pricier than stainless steel bolts.

In conclusion, the two are not simply interchangeable alternatives. Metal bolts act as versatile all-rounders that ensure structural toughness, while 99% alumina bolts serve as specialized commandos that excel in extreme working conditions. Understanding their intrinsic differences is the key to precise application matching, achieving the optimal balance between safety and efficiency.