BOROCOAT®

Borided parts exhibit extremely high surface hardness values, generally ranging from about 1400 HV_0.025 (Vickers hardness) up to approximately 2400 HV. Even for unalloyed steels, the surface hardness can be about twice as high as that of hardened high-speed steel (HSS). The hardness you achieve is only dependent on the chemical composition of the base material; it is not influenced by the boriding process parameters.

The achievable layer thickness primarily depends on the base material, but it is also influenced by treatment temperature and time. The greatest layer thicknesses—up to around 200 µm—are possible on unalloyed and low-alloy steels, as well as cast iron. For components that will be hardened after boriding, or for certain high-alloy steels and nickel-based alloys, a layer thickness between 20 µm and 100 µm is recommended.
Because austenitic stainless steels can see their surface hardness increase by a factor of 8 to 10 through boriding, even a layer thickness of about 20 µm is sufficient to achieve significant wear protection on these materials.

Yes, hardened or tempered parts can be borided. However, boriding can lead to a soft-annealing effect, which might require re-hardening afterward.

Yes, parts can be hardened after boriding to achieve the desired working hardness and strength. It is essential to select the proper hardening process; otherwise, the boride layer could be compromised.

Boriding is an excellent method for hardening the surface layer (case-hardening) of unalloyed steels. It does not require specific alloying elements or carbon. However, the hardness effect is limited to the surface layer only.

Boriding is very well suited for the treatment of complex shapes, hollow bodies, and tubes.

Yes. Bulk goods and mass-produced components can be borided effectively.

No heat treatment process is entirely free from dimensional or shape changes, and this also applies to boriding. Numerous factors can influence dimensional stability, many of which can be controlled to optimize a part’s behavior during heat treatment. Overall, boriding is considered a low-distortion process.

Studies have shown that the coefficient of friction can decrease significantly after boriding. In some cases, a reduction of 30–50% has been observed. This is primarily due to the effective reduction of adhesive wear, thanks to the ceramic character of the boride layer. Notably, sliding properties improve substantially at elevated temperatures.

Yes. Boriding does affect the corrosion behavior of the base material. Corrosion resistance can improve or worsen, depending significantly on the specific base material and the type of corrosive medium involved.

Yes. Boride layers offer higher temperature resistance than nitrided layers. Several factors contribute to this:

• Oxidation resistance: Boride layers show better resistance to oxidation at high temperatures.
• High-temperature hardness: The hardness of boride layers is largely retained at elevated temperatures, whereas nitrided layers can lose hardness as temperatures rise or over prolonged exposure.
• Chemical stability: Borides are chemically very stable and resistant to many aggressive media at high temperatures, whereas nitrided layers can be more susceptible under these conditions.

Typical stability ranges for these layers:

• Boride layers: Usually stable up to about 800–1000°C (or even higher, depending on the material and conditions).
• Nitrided layers: Generally stable up to around 400°C; above that, they start to lose hardness and protective properties over time.

In summary, because boride layers have higher melting points, better oxidation resistance, and maintain hardness at elevated temperatures, they are more temperature-resistant than nitrided layers. This makes them particularly suitable for applications exposed to extreme thermal and chemical stresses.

Because boride layers are extremely hard—sometimes as hard as high-performance cutting tools—post-machining is very limited. Nevertheless, borided surfaces can be ground with CBN grinding wheels or polished with diamond paste if necessary.

Partial boriding is generally feasible. For example, you can boride only the inside or only the outside of a cylinder. It is more challenging, however, to mask areas immediately adjacent to surfaces intended for boriding. For very small parts, partial boriding is usually not practical or worthwhile.

Boriding significantly extends the service life of treated parts, often by a factor of 3 to 8. This helps save large amounts of steel, CO₂, and energy over time, making boriding a highly sustainable treatment method.

Our boriding process does not release any critical substances into the environment. The boriding medium is almost entirely recycled, and the energy source is electricity. This makes our boriding process environmentally friendly, as it produces no toxic waste.

In principle, all ferrous metals, nickel-based alloys, and cobalt alloys can be borided. However, the aluminum, silicon, and copper content should not be too high, as these elements cannot be incorporated into the boride layer and may negatively affect adhesion.

Although the boride layer is formed within the base material (meaning it’s not a “coating” in the traditional sense), the volume expansion in the boride zone does create a slight buildup on the part’s surface. This buildup is about 10–15% of the total layer thickness.

Thanks to their high-temperature resistance (persistently above 1112°F) and ceramic-like properties, boride layers are very resistant to molten metals such as zinc and aluminum. Scientific studies and practical examples have shown excellent resistance to both static and flowing metal baths.