a b s t r a c tSelf-propagating high-temperature synthesis (SHS) was previously proposed as alternative preparation route for FeeAl intermetallics. However, this process was not optimized and the mechanism and kinetics of the phases' formation was not fully clarified up to current days. In this work, in situ high energy X-ray diffraction analysis was carried out during the SHS process and the mechanism of the intermetallic' formation in FeAl25 powder mixture was described during rapid heating and isothermal annealing at 800 C as well as during a slower continuous heating to 900 C. During slower heating, the formation of Fe 2 Al 5 and FeAl 2 intermetallics starts below the melting point of aluminium. When the heating rate is high, intermetallics are created after melting of aluminium. During long-term annealing, all of the phases can be transformed to FeAl phase when fine powders were applied. Detailed mechanism is proposed in this paper and kinetics of the intermetallics' formation is described.
Customization and providing tailored products, while keeping highly automated production with minimum manufacturing personnel, is a general trend, and one of the expectations of manufacturing companies from developed countries to stand in competition against cheap mass production. This trend, often also called “industry 4.0”, is taking advantage of many innovative and quickly developing technologies like AM or 3D printing. Applications of 3D printing are also getting into the field of turbomachinery. The first part of the paper provides a review of current 3D printing technologies with respect to applications in turbomachinery field. Several technologies, mostly for producing a metal or plastic product, exist and can be considered. Applications for the components range from single Watts to hundreds MW scale and similarly for various other operating conditions. The second part briefly describes possible practical applications concerning multiple situations as research and development, customization of end-product, operative field-testing, or temporary replacements.
The paper describes existing requirements for tool materials. In the light of experience with these supplied materials, we have demonstrated their considerable influence on the life of molds for die casting technology. From this research came the evaluation methodology of these tool materials which has been used for directing the development of a new material. Based on the new regulation of the chemical composition a sample was casted and forged after that. Then was determined the process of heat treatment and from a block of this material a mold insert was produced. This insert is now being tested in production.
Greater expansion of distributed power and process systems based on thermodynamic cycles with single to hundred kW scale power output is limited mainly there are not available cost-effective expanders. Turboexpanders have a perspective of high efficiency and flexibility concerning operating parameters even for the micro applications. However, they suffer from a high manufacturing cost and lead time in the development of traditional technologies (such as casting and machining processes). Additive manufacturing provides a possibility to overcome some of the issues. Manufacturing parts with complicated shapes by this technology, combining multiple components into a single part or rapid production by 3D printing for development purposes are among the prospective features with this potential. On the other hand, the 3D printing processes come with certain limitations which need to be overcome. This paper shows a design and manufacturing process of a 3 kW axial impulse air turbine working with isenthalpic drop 30 kJ/kg. Several samples to verify printing options and the turbine itself has been manufactured from stainless steel by the DMLS additive manufacturing method. Manufactured are two turbine variations regarding blade size and 3D printer settings while maintaining their specific dimensions. The turboexpanders testing method and rig is outlined. As the surface quality is an issue, several methods of post-processing of 3D printed stator and rotor blading to modify surface quality are suggested. Detailed experimental investigation is however subject of future work.
In earlier works were described trends in the production of tools for die casting (hot work). Almost the entire set of issues dealt with may seem insignificant when incompletely assembled acceptance of the material and the associated risks of processing a material with an inappropriate structure, leading to a very early defect of the die. Therefore, further work will focus particularly on identifying the causes of thermal cracks and preventing a suitable choice of acceptance criteria conditions and heat treatment.
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