Causes of Corrosion in Laboratory Centrifuge Rotors

Release time:

2014-02-26

Overview:

The corrosion of centrifuge rotors is typically caused by two factors: chemical corrosion and stress corrosion.

During the operation of a centrifuge, why does the centrifuge rotor sometimes become corroded? Let’s take a closer look at the specific causes of centrifuge rotor corrosion.

Rotor corrosion is typically caused by two factors: chemical corrosion and stress corrosion.
　　　　
1. Chemical corrosion on the rotor surface
Under normal circumstances, the surface of an aluminum rotor is coated with an anodized oxide protective film. However, this film is brittle and can easily be scratched by sharp, hard objects if handled carelessly. Acids, alkalis, and detergents can also erode it. Moreover, certain high-concentration salts have a detrimental effect on aluminum rotors; the rotor remains stable only in media with a near-neutral pH (6.5–7.5). In contrast, titanium rotors exhibit excellent resistance to chemical corrosion. Acidic, alkaline, and heavy-metal salt solutions with a pH ranging from 3.5 to 11.0 exert little corrosive action on them. Nevertheless, prolonged exposure of the rotor surface to moisture—as well as certain substances such as chloroform, toluene, cesium chloride, and aluminum oxide—can still cause corrosion over time.
2. Stress Corrosion
The rotor’s service life is determined based on mechanical fatigue strength tests conducted under non-corrosive conditions. However, in actual operation, chemical corrosion can cause localized corrosion spots on the rotor surface, reducing the material’s mechanical properties and leading to stress concentration, which in turn triggers stress corrosion. Even when the applied stress remains below the rotor’s design limit and does not yet reach the service-life threshold, rotor failures due to stress corrosion still occur frequently. Stress corrosion is the primary cause of报废 (scrapping) for aluminum alloy rotors. After the rotor has been in use for a certain period, regular inspections are essential to prevent corrosion.

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