Fraunhofer ISC, Center for High Temperature Materials and Design HTL, Bayreuth
Fraunhofer-Center HTL develops components as demonstrators, prototypes with test capability or performs the manufacturing process for small series in closed process chains. Components developed at the HTL consist of ceramic or metallic materials in monolithic form as well as composite materials or material composites. Material composites can be produced by material and form-fitting joints. Typical component developments include CMC, fibre structures and 3D printed parts including possible combinations, coatings, joinings as well as finishing processes.
Requirement Analysis and Specification Sheet
The specification sheet for prototypes is prepared in conjunction with the customer and includes a precise description of the requirements for the intended use and system requirements such as temperature, service life, thermo-mechanical loads and exposure to corrosive media. The availability of raw materials or purchased parts, preferred manufacturing methods and the budget are taken into consideration as well.
Component Geometry and Material Selection
If not previously specified by the customer, the component geometry and the materials to be used are identified by Fraunhofer-Center HTL. For the material selection, a database with several thousand data records on commercially obtainable materials is available. In this database, materials can be sought according to diverse criteria (e.g. operating temperature, coefficient of thermal expansion, price etc.). The component geometry is usually determined using a finite element (FE) simulation. The most suitable geometry for model components is determined using FE methods in such a way that the test conditions produce loads similar to the loads, which can be expected when the real component is used.
Manufacture of Prototypes
For the manufacture of components, a manufacturing plan for the preferred manufacturing process is usually created based on CAD data. Alternative manufacturing processes are tested to determine the optimum manufacturing process. At Fraunhofer-Center HTL, numerous forming processes and heat treatment steps are available to achieve even complex geometries with high component quality. The focus here is on powder metallurgical processes and processes for the production of CMC. Using additive manufacturing, prototypes in complex geometries can also be produced at Fraunhofer-Center HTL. The forming process is usually followed by heat treatment steps, which can be optimized using systematic methods and realized using the furnace technology available. The surfaces of the components can be protected against environmental influences such as oxidation or corrosion, functionalized or sealed by ceramic coatings. For this purpose, a wide range of ceramic coating systems is available at Fraunhofer-Center HTL.
Examination and Test of Prototypes
Quality control of components can be undertaken at Fraunhofer-Center HTL by non-destructive testing procedures. For this purpose, possible component defects such as pores, cracks, delaminations etc. can be detected. Using computer tomography (CT), dimensional control of very complex and interior structures can be performed. The evaluation of detected component faults can be undertaken by the export of CT data and FE analysis of the stress concentration. Further tests and examination of components under operating conditions, e.g. at high temperatures, are possible at Fraunhofer-Center HTL (see ThermoOptical Measuring devices).
Manufacture of Small Series and Know-how Transfer
If required, Fraunhofer-Center HTL also manufactures small series on customer order, as soon as the properties and geometries of the prototype components meet the customer’s demands. The entire manufacturing process or the individual steps can then be handed over in the form of a technology transfer. As part of such a know-how transfer, patents or licenses from Fraunhofer-Center HTL are also helpful to secure market access for the products.