Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- Additive manufacturing (1)
- Alkaline digestion reaction (1)
- Ceramics (1)
- Defect detection (1)
- Electrostatic filter ash (1)
- Katoite (1)
- Lattices (1)
- Paper sludge combustion ash (1)
- Portlandite (1)
- Quality assurance (1)
Organisationseinheit der BAM
This paper investigates fast and inexpensive measurement methods for defect detection in parts produced by Additive Manufacturing (AM) with special focus on lattice parts made of ceramics. By Lithography-based Ceramic Manufacturing, parts were built both without defects and with typical defects intentionally introduced. These defects were investigated and confirmed by industrial X-ray Computed Tomography. Alternative inexpensive methods were applied afterwards on the parts such as weighing, volume determination by Archimedes method and gas permeability measurement. The results showed, that defects resulting in around 20% of change in volume and mass could be separated from parts free of defects by determination of mass or volume. Minor defects were not detectable as they were in the range of process-related fluctuations. Permeability measurement did not allow to safely identify parts with defects. The measurement methods investigated can be easily integrated in AM process chains to support quality control.
Industrial wastes (bottom ash, crushed concrete fines, filter residue, paper ash and lignite fly ash) have potential for use in building materials, for instance as raw materials for clinker production, as supplementary cementitious materials (SCMs) or mineral additions in concrete. The properties of the products are dependent on the reactivity of the waste materials used, which can be classified as inert, latent hydraulic or pozzolanic. In this study, waste materials were first characterised. This was followed by theoretical considerations of the mentioned application options. Experiments were limited to evaluation of potential as SCMs and, for this purpose, activity index measurements and calorimetric and thermogravimetric analyses were performed. Finally, the synergetic effects of various waste materials were considered. Paper ash (calcium oxide source) and filter residue (amorphous silicon dioxide source) showed the best prospects for use as cementitious material components.
This paper is a case study of complete substitution of sodium-metasilicate in zeolite Na-A synthesis by an electrostatic filterash (FA) arising in high amounts during silane waste incineration process.The silicate abundant FA is a suitable material for reinsertion in zeolite chemistry. This is shown in the presented investigation by the development of a model reaction process at low temperatures (50–60 °C) and short times (1.5–4 h). The experiments were performed under addition of NaAlO2 and variation of the alkalinity and the reaction period. Characterization and fine tuning of the process was mainly done by studying the kinetics of FA digestion and zeolite crystallization by XRD and chemical analyses (ICP-OES) of solutions and solids. It could be shown that pure FA was mostly dissolved (98%) in 8 m NaOH already after 1 h. Addition of NaAlO2 and crystallization for further 60 min under optimized conditions at 50 °C yielded to a suitable product. It consists of zeolite Na-A (92% by mass) beside some hydrosodalite (8% by mass). According to this low temperature short time process this study is a contribution for the development of energy efficient recycling solutions.
Alkaline reactions of paper sludge combustion ash at low temperature (60 °C) were performed using a calcite-rich paper ash (PA 1) and a gehlenite-rich ash (PA 2). Strong alkaline conditions (8, 12, 16 M NaOH) were revealed at reaction times of 1–4 h and 12–24 h. Reactions were performed with pure ashes and in the presence of NaAlO2. The products were characterized by XRD, FTIR, SEM/EDX, gravimetry and chemical analysis. The conversion was found to proceed mainly in the period between 1 and 4 h. Portlandite and hydrogarnet were observed from PA 1 in 8 M NaOH. Onset of formation of Ca4Al2O6CO·311H2O beside Ca(OH)2 could be analyzed after reaction of PA 1 in 12 M and 16 M NaOH. Addition of NaAlO2 favored crystallization of hydrogarnet and Ca4-Al2O6CO·311H2O. For PA 2 gehlenite remained stable, but a high portlandite fraction was observed. Addition of NaAlO2 yielded hydrogarnet beside gehlenite in 8 M NaOH. Higher alkalinities favored crystallization of Ca4Al2O6-CO·311H2O and onset of dissolution of gehlenite. Finally transformation of Ca4Al2O6CO·311H2O into sodium aluminum silicate hydrate was observed. All results were discussed with regard to heavy metal distribution of the initial PA between the alkaline digestion solution and the products. In conclusion suitable applications of the products were proposed.