Research

As part of a collaborative project funded by the Sächsische Aufbaubank (SAB) under the ERDF, the Chair of Materials and Surface Engineering at Chemnitz University of Technology, SITEC Industrietechnologie GmbH and CMMC GmbH are developing novel aluminium matrix composite(AMC) materials for laser beam cladding. The aim is to harness the potential of this class of materials – which are lightweight yet highly resistant to wear and corrosion – for additive manufacturing and coating processes.
AMC materials typically consist of aluminium alloys reinforced with 5–30 vol.% SiC particles, thereby exhibiting high mechanical and tribological performance combined with low density. The project aims to establish an end-to-end process chain for the production and processing of suitable AMC materials. This comprises the production of suitable AMC semi-finished products by CMMC GmbH, their conversion into high-quality powders via ultrasonic atomisation at Chemnitz University of Technology, and the processing of the composite powders into wear-and corrosion-resistant coatings by laser beam cladding at SITEC Industrietechnologie GmbH.
Through close collaboration between the project partners, fundamental relationships between material composition, process parameters, microstructure and the resulting properties of the AMC powders and coatings are being systematically investigated. On this basis, high-quality AMC composite powders, optimised for specific processes, are to be produced. The project thus strengthens the innovative capacity of additive manufacturing and coating technologies and contributes to the development of resource-efficient lightweight construction solutions in Saxony.

Electromagnetic forming (EMF) utilises the energy density of pulsed magnetic fields to apply force without contact and to carry out high-speed forming of highly electrically conductive workpieces. The high strain rates inherent to the process result in increased formability for many materials, enabling the forming of complex geometric features. Due to the combination of high mechanical strength and high electrical conductivity, copper alloys such as CuCrZr are now predominantly used as inductor materials in the EMU process. However, the resource-efficient and cost-effective design of the forming process is currently limited by the highly variable service life of the inductor. Despite numerous studies on electromagnetic forming, the mechanisms that lead to damage to the inductor—in some cases after just a few discharges—remain unclear to this day. In order to optimally design the inductor for the process and ensure the stability of its operational properties for a long service life, an understanding of the underlying process-structure-property relationships is necessary. As part of this project, the causal relationships between the inductor’s material microstructure—which directly influences its mechanical and electrical properties—its geometry and surface condition, as well as between the process parameters and the associated electro-thermo--mechanical stresses on the inductor, in order to gain a fundamental understanding of the damage processes and mechanisms occurring during EMU. Through the qualitative and quantitative evaluation of these influencing factors, conclusions can be drawn regarding the potential extension of the service life of the inductors, thereby ensuring a resource-efficient and cost-effective design of the forming process.

Increased environmental requirements for internal combustion engines and economic pressures within the automotive supply industry call for technologically and economically superior components, such as bearing shells, and a solution that is free from toxic lead, offers higher strength and utilises alternative process routes to the current state of the art. The aim of the project is to develop a holistic manufacturing route for bearing shells using powder processing via thermal spraying, as the requirements for bearing shells make a composite material essential. In this project, aluminium-based alloys are being developed and processed into powders via gas atomisation for application using HVOF. A new burner and nozzle geometry, along with optimised processing parameters, are being developed to enable the coating of such low-melting-point alloy systems. A comprehensive analysis of the coating process, the parameters and the resulting coatings enhances technological understanding and ensures quality. Finally, coated bearing shells will be tested under realistic operating conditions in internal combustion engines, thereby achieving TRL6. Within the scope of this project, Chemnitz University of Technology is responsible for coating development and the associated determination of optimal spraying parameters, and is therefore closely integrated with the sub-projects (powder production, burner prototype design, component post-processing and analysis) of the participating project partners.

The project investigates the potential applications of microwave plasma torches in thermal processing systems and compares them with conventional hydrogen and natural gas burners. To this end, a wide range of process parameters – such as feed gases, temperatures and mixtures – are systematically varied in order to investigate in detail the effect of microwave plasma torches on furnace lining materials. Based on these findings regarding plasma properties, the integrity of the burner components and process safety, recommendations can then be derived for the use of microwave plasma torches in existing and new thermal processing plants.

The aim is to develop an electrically driven refrigerant compressor (eKMV) with increased energy efficiency, reduced weight and improved resource efficiency. To this end, a novel 9-kW compressor is being designed which, thanks to design simplifications, offers more cost-effective manufacturing and increased operational reliability. To extend the operating range and improve thermodynamic efficiency, a medium-pressure feed is being integrated into the compression process. This involves introducing refrigerant at an additional pressure level, thereby reducing the final compression temperature and increasing process stability. Another key focus of development is the replacement of conventional grey cast iron components with SiC-particle-reinforced aluminium matrix composites (AMC) for the cylinder housing.
As part of the collaborative project, a functional prototype and a technically optimised eKMV with integrated medium-pressure injection are being developed and tested. In addition, fundamental issues relating to materials and process development are being investigated. Furthermore, the reintroduction of machining swarf into the initial forming process is being investigated in order to develop recycling strategies for AMC materials and to assess their impact on the mechanical properties of the components. In addition, a sustainability assessment is being carried out using a cradle-to-cradle analysis.

The objectives of the Bladeprotect³ – OVBA sub-project are the selection and optimisation of materials, as well as the development of a process for metallising the leading edges of wind turbine rotor blades using thermal spraying. To this end, the proposed project will develop a manufacturing process chain in which the individual technologies work together to form coordinated sub-processes. A key focus at Chemnitz University of Technology is the development of metallic alloys that enable high bond strength to the rotor blade substrate and provide multifunctional protection within a coating system comprising a bonding layer and a functional top coat. A key aspect of this is the selection of filler materials and the investigation of modifications to the material composition with regard to functional properties. Furthermore, a solution for coating application via wire arc spraying using the previously developed metallic alloys is proposed, which represents a new approach in the field of wind energy. The technical functionalities of these metal coatings are comprehensively characterised in terms of their microstructure, adhesion strength and relevant property parameters. Building on this, the development and optimisation of coating parameters for wire arc spraying are investigated. Furthermore, the systematic investigation extends to the parameters for the surface preparation of the rotor blade substrates. As the coating adhesion mechanism is essentially characterised by mechanical interlocking, the topography and roughness of the substrate contribute significantly to the quality of adhesion. Using fractal design principles, a quantitative estimate of the bond strength – and thus the suitability for the intended application – can be developed. Finally, functional tests are carried out to validate the practical suitability of the coatings. These include electrochemical corrosion and tribological measurement methods carried out in a laboratory setting. The technical functionality of the multifunctional protective coating is characterised by high adhesion strength and a microstructure with few defects, whilst simultaneously exhibiting promising functional properties.

Meeting the growing demands in surface engineering – such as hardening surfaces in a targeted manner, for example through plasma nitriding, and determining the required process controls with precision – requires not only an in-depth understanding of the process but also extensive process development. To reduce the amount of experimental work required for this, numerical, model-based simulations are increasingly being used. However, state-of-the-art methods only allow plasma nitriding to be simulated under certain simplifications. Modern developments in mathematical modelling, information technology and mathematical algorithms enable the analysis of complex models with a high degree of precision. The project involves incorporating the effects of nitrogen and carbon contents – specifically their displacement mechanisms and solubility limits – on the phase transformations during plasma nitriding. In addition to mathematical modelling, the inverse calculation of the physical model parameters from plasma-nitrided layers is also a key part of the project. For the simulation, highly stable numerical methods developed in recent years are being put into practice.

The aim of the project is to determine and predict the influence of hydrogen addition in thermal processing plants on the mechanical properties and service lives of heat-resistant steels under combined thermochemical and cyclic mechanical loading, under conditions relevant to industrial applications. The results of these investigations are made available to plant manufacturers, service providers and materials suppliers. The data provide evidence of the corrosion behaviour and mechanical strengths of the materials used and their joint zones under the altered conditions of hydrogen combustion. This enables companies in the sector – particularly SMEs – to design future plants more precisely and to adapt existing plants in a targeted manner for use with hydrogen. The insights gained allow for the extension of costly maintenance intervals and the avoidance of unplanned plant outages. The aim is to ensure that the use of these materials in industrial systems fuelled by hydrogen is reliable, efficient and safe, thereby facilitating the transition to a low-carbon and sustainable energy supply.

CoCrMo is the standard alloy for dental implants and is currently produced almost exclusively by casting. 3D printing offers significant advantages in this regard in terms of customisation and design freedom. Against the backdrop of the growing market trend towards patient-specific treatments in dentistry, there is an increasing demand for efficient, bespoke implant solutions. However, a major technical challenge for successful market entry is the surface quality of additively manufactured parts, as the powder-bed fusion process leads to undesirable particle adhesion. The development of a holistic, closed-loop process chain offers a promising solution here to overcome this hurdle and make the technology viable for patient-specific implant restorations.
The aim of the project is to develop a comprehensive additive manufacturing process for CoCrMo dental implants. The focus is on optimising the alloy composition in terms of wear resistance, passivity and biocompatibility. In addition, robust and reproducible printing parameters must be developed for complex geometries. The surface finish is first specifically improved using electrolytic plasma polishing (EPP) to remove any roughness caused by the printing process. Finally, the surface is functionalised using a physical vapour deposition (PVD) coating to further optimise the biocompatibility of the implants and enable optimal tissue integration.
The partners include AddPark and plasotec GmbH (manufacturing and processing), as well as Chemnitz University of Technology and Atatürk University (alloy and powder development, surface treatment and biocompatibility studies).

Thermal spray coatings are used in numerous industrial applications, including to improve wear and corrosion resistance and to specifically tailor electrical and thermal properties (insulation or conductivity). Due to the highly dynamic nature of the spraying processes and the complex interactions between process parameters, particle properties and coating formation, quality control is of particular importance. However, currently available testing methods are often destructive, time-consuming or can only be used to a limited extent in-process. There is therefore a considerable need, particularly for small and medium-sized enterprises, for a fast, cost-effective testing solution that can be used on-site.
The aim of the IGF project ‘CoatAlyse’ is to develop a portable, non-destructive rapid test for the quality-related characterisation of thermally sprayed coatings directly in the production environment. By analysing electrochemical corrosion parameters using gel electrolytes and a customised measuring cell, the aim is to establish a robust correlation between the measurement signal and key coating properties. This will enable quality assessment close to the production process, reduce scrap and sustainably improve process stability. In the long term, ‘CoatAlyse’ aims to enable SMEs to monitor the quality of thermally sprayed coatings more efficiently and to strengthen their competitiveness in a targeted manner.

The overall objective of the Hy²Cycle collaborative project is to develop resource-efficient and recyclable cells and stacks for fuel cells (FC) and electrolysers (EL). New concepts for reversible and recyclable high-pressure alkali electrolyser/FC and PEM electrolyser/FC systems are being developed jointly. The development of recycling-friendly designs ranges from cell design through to energy-efficient manufacturing and, as a result of stack development, aims to take into account and implement novel recycling processes in line with a circular economy right from the design stage.

Hy²Cycle is a collaborative project run by the Saxon Hydrogen Union.

Green hydrogen plays a central role in the transition to a low-carbon and sustainable energy future. Efficient production is crucial to utilising hydrogen as a viable and scalable solution, ensuring economic viability, conserving resources and reducing the impacts of climate change. Alkaline water electrolysis (AEL) is particularly well-suited to the large-scale production of green hydrogen due to its robustness and sustainability. It is characterised by high system stability and a long service life. Furthermore, it offers a high tolerance to fluctuations in the power supply, which makes it particularly attractive for operation with renewable energy sources. The performance of the cathodes plays a central role in the overall efficiency of the electrolysis process. It depends largely on the available reaction surface area, the electrical conductivity and the catalytic activity of the material. Cost-effective solutions therefore rely on non-precious-metal-based electrode materials. Nickel-based systems offer a balanced approach in terms of cost-effectiveness and efficiency. One approach to enhancing the performance of such materials is to increase the reactive surface area. Fine-pored, open-pored structures are particularly suitable for this purpose, as they enable improved gas diffusion and optimised mass transfer. Thermally sprayed coating systems are particularly well-suited to this approach. By precisely adjusting the porosity and internal surface area, catalytic activity can be increased, gas bubble detachment improved and mass transfer optimised, which enhances both the electrolytic performance and the durability of the electrodes. Raney nickel represents a promising basis for thermally sprayed coatings due to its high catalytic activity and stability in alkaline media. In the planned project, new nickel-based alloys will be developed and processed by thermal spraying, with the internal porosity specifically increased through the selective leaching of components of the coating system. This results in a large-area, highly active and structurally stable cathode surface. The resulting porous cathode structure will be tested on an industrial scale to assess its potential for improving hydrogen production efficiency and reducing energy consumption in alkaline electrolysis.

Green hydrogen is regarded as a promising zero-emission energy carrier for meeting the targets of the Climate Action Plan 2050 and developing a circular energy system. The development of innovative cathode solutions is essential to achieving competitive production via alkaline water electrolysis. This project aims to develop nickel-aluminium-based Raney nickel cathodes, which are produced by thermal spraying and activated by leaching. This combination of processes significantly increases the specific surface area of the open-pored sprayed structure through the partial removal of aluminium-rich phases, thereby improving cathode performance. Novel wire-in-wire materials are used as filler wire additives, enabling alloy modification whilst maintaining homogeneous processing properties. Through detailed characterisation of microstructural and functional properties throughout the entire process chain, the aim is to initiate the cost-effective production of green hydrogen on an industrial scale.

The focus of sub-project B03 is on establishing an active, defined fibre orientation in short- and long-fibre-reinforced plastics (FRP) and a defined transition zone at the interface with continuously reinforced or non-reinforced substructures. Active alignment of the fibres is to be achieved by means of external magnetic excitation in an isostatic state. The research focuses on developing a suitable coating process for the production of magnetically coated carbon fibres (mc-CF), as well as the production of polymer composites incorporating mc-CF, and the associated experimental and numerical investigation.
This sub-project forms part of the DFG Collaborative Research Centre “SFB/TRR 402”. The project is dedicated to the development of novel production technologies for lightweight structures that are resource-efficient, sustainable and, at the same time, high-performance. The aim of these technologies is to significantly reduce energy consumption and carbon dioxide emissions both during production and during the operation of vehicles and machinery. The focus is on optimising the transitions between different materials in fibre-reinforced plastic composites. These transitions currently present one of the greatest challenges for mass production, as they significantly influence the load-bearing capacity and service life of the components. With the help of what is known as 3D grading, the aim is to produce smooth material transitions that are specifically tailored to the load requirements of the components. This method allows for a gradual change in the reinforcement structures, which improves the mechanical properties and optimises material usage.

The AlSiCoat research project is developing a sustainable coating concept for blades used in agricultural machinery. The aim is to replace conventional tungsten carbide–cobalt-based wear-resistant coatings with more environmentally friendly alternatives. These established systems contain critical raw materials such as tungsten and cobalt and are coming under increasing regulatory and environmental pressure.
The project therefore aims to develop novel aluminium metal matrix composites (AMCs) with embedded silicon carbide (SiC) particles. For the first time, these powders are to be produced from semi-finished AMC castings and applied to machine tools’ cutting edges using laser cladding. The combination of innovative powder production, an optimised coating process and application-oriented testing is intended to result in wear-resistant, tribocorrosion-resistant coatings.
The sub-project led by Chemnitz University of Technology (IWW) focuses on the development of a test method and a test rig for assessing combined wear and corrosion resistance. To this end, a tribocorrosive, unidirectional abrasion wear test is being developed which replicates the real-world operating conditions of agricultural tools as closely as possible. The results enable a quantitative assessment of the new coatings and support the optimisation of the entire process and materials system.

Many components must withstand periodically occurring load cycles throughout their service life. Long service lives with high allowable loads are of great technical and economic interest in this context. For components subjected to this type of cyclic loading, it is necessary to select suitable materials and optimise the geometric design to achieve high realisable fatigue strengths. Specified minimum fatigue life cycles, tailored to the specific application, must be withstood without the formation of cracks. As the component surface is the preferred location for crack initiation under high-cycle fatigue (HCF) loading, the geometric and material properties have a decisive influence on the cyclic load-bearing capacity and thus on the fatigue strength. This means that, in addition to strength, hardness and macroscopic surface topography, the notch effects resulting from microstructural features at the microscale also exert an influence. However, the mechanisms by which these microstructural factors influence fatigue strength have so far been inadequately investigated. The aim of the project is to characterise the influence of the near-surface microstructure on fatigue strength not only qualitatively but also quantitatively, in comparison with the macroscopic, manufacturing-induced surface topography, in order to take all relevant factors into account when designing a component to achieve improved operational properties.

The industrial manufacture of components involves the sequential linking of manufacturing processes to produce products with a defined set of properties. The challenges lie in optimising the manufacturing process, addressing uncertainties inherent in the process, and achieving global optimisation across the entire process chain. Multi-criteria optimisation is challenging, as there are conflicting target parameters relating to processing and functional properties.

Process chain optimisation is to be carried out in ProModFun using an experimental approach and data-driven modelling. First, the process chain comprising (1) thermal coating, (2) turning and (3) diamond smoothing will be established to produce a functional surface with a graded increase in hardness close to the surface. The innovative property profile is to be demonstrated using the ‘guide roller’ component as an example. Through thermal coating (primary shaping), surfaces made of manganese hard steel are applied to rotationally symmetrical components and then adjusted in terms of core and edge properties by turning and diamond finishing. The target parameters of the process chain to be optimised are to be influenced as follows: (1) maximise surface hardness, (2) minimise surface roughness, (3) maximise the oxide content of the coating system, and (4) maximise the energy efficiency of surface production.

Sensor technology is integrated into the manufacturing processes and the measurement data is used for modelling. The methodological approaches employed are statistical modelling and multidimensional, pattern-based description using grey-box AI algorithms (fuzzy pattern classification). These enable the quantification of various types of uncertainty and the forward coupling of the process chain. This is followed by the development of a method for inverse multi-criteria optimisation across the entire process chain for the purpose of global optimisation.