Does tungsten carbide rust?

Does tungsten carbide rust? Pure tungsten carbide does not rust under normal temperature and pressure. Pure tungsten carbide is highly stable in dry air at room temperature; an extremely thin oxide film (primarily WO₃) forms on its surface, preventing further oxidation. Therefore, significant corrosion almost never occurs in everyday environments (such as indoors, at room temperature).

Under extreme conditions, tungsten carbide may oxidize:

High-temperature environments (>500–600°C):
At high temperatures, tungsten carbide reacts with oxygen: WC + 5O₂ → 2WO₃ + 2CO₂. A yellow or bluish-purple tungsten trioxide (WO₃) layer forms on the surface. The oxidation of tungsten carbide is fundamentally different from the rusting of iron. The rusting of steel causes corrosion and the flaking off of the corroded layer. The oxide layer of tungsten carbide is dense; the generated WO₃ film is relatively dense, protecting the internal material and not causing progressive corrosion. Tungsten carbide may oxidize under the following extreme environments:

Strong oxidizing media:
Exposure to concentrated nitric acid, hydrofluoric acid, or molten alkali may cause corrosion.

Long-term humid and hot environments:
Although slow, prolonged exposure to high-temperature and high-humidity environments may accelerate surface oxidation.

Pure tungsten carbide is not used alone in industrial materials; it is generally mixed with metallic cobalt, commonly known as cemented carbide. This article will also discuss the rusting situation of cemented carbide products.

I. Whether cemented carbide material rusts
Cemented carbide is an alloy material made from hard compounds of refractory metals and binder metals through powder metallurgy. Its main components are tungsten carbide and cobalt, possessing characteristics such as high hardness, wear resistance, good strength, and toughness. Since the main components of cemented carbide, tungsten carbide and cobalt, are not easily oxidized metals, and they undergo special treatment during the production process, they are endowed with excellent corrosion resistance. Therefore, cemented carbide does not rust at room temperature and pressure either.

In practical applications, the corrosion resistance of tungsten carbide has been fully validated. Whether in harsh environments such as high temperature, high pressure, high humidity, strong acids, or strong alkalis, tungsten carbide can maintain stable performance. This makes tungsten carbide widely valuable in fields such as CNC cutting insert tools, wear-resistant parts, and mining drilling tools.

Of course, although tungsten carbide is not prone to rust, it may still be corroded under certain special conditions. For example, its performance may be affected to some extent under extremely high or low temperatures. Additionally, certain strong oxidizers or reducing agents may also cause corrosion to tungsten carbide. Therefore, when using tungsten carbide, it is still necessary to make reasonable selections and maintenance based on specific application environments and conditions.

How to maintain cemented carbide products to prevent rust
Whether it’s cemented carbide or tungsten carbide products, correct maintenance is crucial. Here are some suggestions to help you prevent rust on these materials:

1.Avoid prolonged exposure to harsh environments such as high temperature, high humidity, strong acids, or strong alkalis.

2.Clean regularly to remove surface dirt and impurities. Use mild detergents and soft cloths for wiping; avoid using strong chemical cleaners.

3.For cemented carbide products, regularly inspect whether their surface treatments (such as plating, coatings) are intact. Repair any damage promptly.

4.During storage, maintain a dry and ventilated environment, avoiding moisture and water accumulation. Rust inhibitors or desiccants can be used for auxiliary protection.

In summary, due to its unique chemical properties and structural characteristics, tungsten carbide is not prone to rust and possesses excellent corrosion resistance. This gives tungsten carbide broad application prospects in multiple fields. At the same time, we also need to be aware of the potential corrosion issues tungsten carbide may face under certain special environments to ensure its stability and reliability during use.

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