RATH – We Have Established a European Source for Oxide Ceramic Continuous Fibers

Vienna, September 2025

PW: Mr. Krause, ALTRA FLEX® is described as a groundbreaking material for high-temperature applications. What were the biggest challenges in developing this oxide ceramic continuous fiber?

Axel Krause: One of the main challenges lies in the close interdependence of the production steps. Each stage of the process is highly interconnected – seeing it firsthand is truly impressive. There are very few isolated steps in manufacturing, which in practice means strong interactions between different stages. These interactions are often indirect, meaning unfavorable settings might only show their effects much later in the process chain. Identifying critical parameters therefore requires great skill and results in longer development cycles. Our R&D department has shown tremendous perseverance in this regard.

PW: That sounds like years of development work. Does this effort also pay off in terms of sustainability? How does ALTRA FLEX® contribute to reducing energy consumption or industrial emissions?

Axel Krause: That’s indeed an interesting aspect. At first glance, production may indeed appear energy-intensive, especially if you look at it on a mass-based level. But when viewed holistically over the lifecycle of the end component, the picture can quickly reverse. Depending on the application, we can achieve significant weight savings, longer service or maintenance intervals, or simply greater process stability. This leads to fewer – or ideally no – downtimes of systems and reduces the weight of kiln furniture that needs to be heated and cooled during thermal processing.

PW: You mentioned weight advantages. That must be particularly relevant for aerospace applications.

Axel Krause: Absolutely. The effect is even more pronounced in the aerospace sector. Every kilogram that doesn’t have to be lifted into the stratosphere – in the case of commercial aircraft in frequent, repetitive cycles – or even into orbit translates into huge fuel and CO₂ savings. A long-haul passenger aircraft covers between 5.4 and 7.2 million kilometers per year, roughly equivalent to 150 circumnavigations of the Earth. Imagine the impact of saving just a few kilograms over the entire lifetime of such an aircraft.

PW: What specific applications do you see in aerospace?

Axel Krause: The potential is substantial. In engine systems, there are high thermal and mechanical loads where ceramic matrix composites (CMCs) are ideal. Typical applications include heat shields and turbine components, where existing metal-based solutions can be replaced. Another benefit of ceramic composites is their electromagnetic transparency, which makes them ideal for radomes, sensor housings, and other functional parts that must be protected from external influences without impairing performance.

PW: Did you develop the technology entirely on your own or were there partners involved?

Axel Krause: We developed the technology as part of a Europe-wide project – InVECOF, which stands for Innovative Value Chains for European Ceramic Oxide Fibres. We work closely with our research and industrial partners, both upstream and downstream in the value chain. The fact that our Mönchengladbach plant now provides a European supply source for oxide ceramic continuous fibers has been very well received and met with strong positive feedback from the market.

PW: What are the next steps? Are you preparing for a rollout?

Axel Krause: Our next goal is to evaluate the new grades for different application fields and establish corresponding supply and production structures. Since these applications often involve sensitive sectors such as aerospace, this first step must be taken with great care. In parallel, we are working to continuously improve the quality, availability, and diversity of our products. This process is being driven by our in-house R&D but will likely also involve external partners for certain application areas.

PW: How do you see the overall CMC market developing in the coming years?

Axel Krause: Although CMCs first appeared in the 1970s and 80s, commercialization only really began in the 1990s – and even today, it’s still in a relatively early stage compared to other material systems. In the refractory sector, continuous oxide ceramic fibers are gaining importance both as fabrics for seals or fiber protection and as part of CMC-based kiln furniture or functional components that face extreme thermal and thermal-shock stresses.

PW: Where do you see ALTRA FLEX® being used specifically in the refractory industry?

Axel Krause: Depending on the application, burner and flame tubes or hot-gas valves are prime candidates – areas where other materials tend to fail prematurely. As the availability of base components increases and product properties improve further, CMCs will gradually find their way into many more applications beyond refractories and aerospace – the benefits are obvious. However, it can take several years before these advantages are realized in practice, since the qualification and validation of new components, particularly in aerospace, is a time-consuming process.

Further information about RATH and ALTRA FLEX® can be found at: https://www.rath-group.com/en/altraflex 

About the Author:
Axel Krause graduated with a degree in Ceramics, Glass and Building Materials Engineering from the TU Bergakademie Freiberg and has worked in the refractory industry ever since. For over 10 years, he has applied his technical expertise in various sales-related positions and is currently responsible for sales of ALTRA FLEX® fibers at RATH AG.