Fraunhofer Institute for Surface Engineering and Thin Films IST
The new gas boriding plant at Fraunhofer IST uses diffusion treatments at temperatures of up to 1,050 °C to create boride boundary zones with exceptional technological properties.
Boride surfaces for high-temperature applications
In forming processes, extreme thermal stresses are among the greatest challenges for tools and components. High temperatures accelerate wear, promote adhesion, and significantly reduce service life. At Fraunhofer IST, boride surfaces are therefore being developed using PECVD or gas boriding processes, which are particularly suitable for complex geometries in tools and components for high-temperature applications. The resulting layers and boundary zones protect against abrasive wear, reduce adhesion, and thus contribute to extending tool life.
Nanostructure investigations of a quinary boron-based Ti-Si-B-C-N layer show nanocrystalline phases in the TEM image (bright field mode).
The recently available high-temperature furnace enables investigations in the temperature range of up to 1,600 °C.
A cross-section of a TZM material after boriding and tempering.
Challenges in industrial high-temperature forming
Typical industrial high-temperature applications include die forging of steel, extrusion of copper alloys, and forming of titanium alloys. These processes place extreme demands on tool surfaces: high thermal stability at process temperatures often reaching 1,000 °C or more, extreme hardness, and chemical inertness to reduce adhesion during forming operations. In addition to hot work steels, molybdenum alloys such as TZM or nickel-based alloys such as Nimonic® 75 are therefore used.
Innovative protection systems for tools
To meet these extreme thermal and tribological requirements, the Fraunhofer IST is pursuing two innovative approaches: On the one hand, plasma boriding produces boride phases through diffusion with excellent bonding to the base material and hardness values of 2,000–3,000 HV, combined with high thermal stability (see Figure below). On the other hand, quinary boride PACVD coatings (Ti-Si-B-C-N) form nanocomposites consisting of 4–7 nm nanocrystalline grains embedded in an amorphous matrix with hardnesses of up to 40 GPa and oxidation resistance up to 925 °C (see Figure above).
Testing and qualification of surface solutions
In order to transfer these approaches to industrial applications, the developed solutions for the surfaces and edge zones of the forming tools and components are systematically qualified through various model tests and investigations. At pilot scale, a vacuum high-temperature furnace (up to 1,600 °C, < 10-5 mbar or, for example, under hydrogen atmosphere, see middle Figure) and a special tribometer are available for this purpose. Ring compression tests and production near forging trials are carried out in cooperation with the Institute of Forming Technology and Machines IFUM at Leibniz University Hannover and the Fraunhofer Institute for Machine Tools and Forming Technology IWU. Further evaluation takes place in industrial series investigations, e.g., within the framework of IGF projects.
Outlook: Scaling and New Technologies
Based on the development and research results achieved to date, both approaches will be further developed at Fraunhofer IST in the future. From mid-2026, a new gas boriding plant (up to 1,050 °C) and a modernized PACVD system for the application of quinary Ti-Si-B-C-N systems will be available for this purpose. Please contact us for an application-specific wear protection solution under high-temperature conditions.