ALTRA FLEX®: RATH is the first European manufacturer and supplier of oxide ceramic continuous fibre
Recently, the international refractory manufacturer started production of the innovative ALTRA FLEX® oxide ceramic continuous fibre in K99 and M75 qualities. RATH has been developing oxide ceramic continuous fibre for several years. The production plant for the manufacture of the ALTRA FLEX® oxide ceramic continuous fibre in K99 and M75 qualities was recently commissioned at the RATH Mönchengladbach site (Germany). This makes RATH the first European supplier to offer a solution for manufacturers of composite materials and manufacturers and processors of temperature-resistant fabrics. The new production plant will initially produce up to 10 tons of fibre per year.

“Drawing on 35 years of experience in the development and production of high-temperature ceramic fibre, RATH is always looking for innovative ways to develop new, pioneering product solutions for industry. The addition of ALTRA FLEX® oxidic ceramic continuous fibre in two grades has enabled us to once again expand our broad portfolio of pioneering solutions”, says Christopher Kluthe, Senior R&D Manager, RATH. “ALTRA FLEX® is unsurpassed in the industry and maintains both strength and flexibility up to 1200 oC”, adds Christopher Kluthe. Other advantages include high thermal shock resistance, excellent dimensional stability and low thermal conductivity.
Ideal for a wide range of applications, from 3D printing to composites
The properties, especially the retention of flexibility in extreme temperature ranges, open up many possibilities. The roving is ideal for fabrics, 3D printing, composites, weaving, braiding and more. These product properties make ALTRA FLEX® a future-oriented material in many industries and fields of application.
ALTRA FLEX®: important raw material for the production of oxide ceramic matrix composites

Oxide ceramic continuous fibre is widely used, especially as reinforcing fibres in various matrices (CMC, MMC). Due to its high tensile strength and stiffness as well as its excellent chemical and thermal resistance, continuous fibre can, for example, provide ceramic matrices with quasi-ductile, damage-tolerant fracture behavior. “This continuous fibre is an important raw material for the production of oxide ceramic matrix composites”, concludes Christopher Kluthe.
An annual production of up to 10 tons of ALTRA FLEX® oxide ceramic continuous fibre is planned
The fibre, produced using the sol-gel process with a dry spinning technique, has a mullite or corundum microstructure after its thermal treatment. To date, RATH has developed the corundum fibre K99 (with a tensile strength of up to 3,000 MPa and an E-modulus of over 350 GPa) and the mullite fibre M75 (with a tensile strength of up to 1,500 MPa and a modulus of elasticity of over 200 GPa). Other qualities, especially those with higher creep resistance, are already in development. Initially, up to 10 tons of ALTRA FLEX® oxide ceramic continuous fibre are to be produced annually in the new production plant in Mönchengladbach. ALTRA FLEX® is a product of RATH Research and Development and was created as part of the HORIZON EUROPE project InVECOF (Innovative Value Chains for European Ceramic Oxide Fibres).
About RATH
RATH specialises in refractory technology with a broad product range of refractory materials for application temperatures of up to 1800 °C. RATH AG, headquartered in Vienna, has established itself internationally as a renowned supplier of refractory solutions, with around 600 employees and sales representatives in several countries worldwide. The RATH Group manufactures a wide range of innovative, high-quality refractory products at a total of seven production sites in Europe (Austria, Hungary, Germany) and the USA. The company produces dense bricks, unshaped products, lightweight refractory bricks, pre-cast blocks as well as high-temperature insulation wool and vacuum-formed parts. Whether it’s in the aluminum, glass, ceramic or steel industries, RATH’s specialists have extensive expertise for these and many other sectors, and understand their specific requirements and processes. For many years, RATH has also been developing innovative hot gas filter elements that enable industrial companies to efficiently filter exhaust gases and pollutants. In addition to supplying standard materials, RATH provides support in the form of complete solutions and a comprehensive range of services – from planning, assembly and site supervision to maintenance and repair. When it comes to the manufacture of its products, RATH attaches great importance to the efficient and resource-saving use of materials as well as to a sustainable approach to the environment. In addition, the company intensively supports its customers to become more sustainable with energy-saving refractory solutions as well as innovative hot gas filter elements for filtering particle-laden industrial flue gases.