Niedrigtemperaturfügen durch Diffusionsschweißen. - In: Fügen mit minimaler Grundwerkstoffbeeinflussung, (2005), S. 10-17
Effect of superposed electro-magnetic fields on the surface treatment of metallic materials. - In: Lasers in manufacturing 2005, (2005), S. 317-322
In the last years laser beam cladding was recognised as a high quality coating process, but the process efficiency is very low and the running costs are high. The flexibility and the effectiveness of laser cladding can be widely increased through free forming (shaping) of the coating. The geometric shape of the coating seam is mainly defined by gravity and surface tension of the melt. An additional force, as for example Lorentz forces, can optimize the geometry in order to improve the process. Wide coatings allow for example a low number of overlapping layers when coating large areas. Slim coatings on the contrary are advantageous when generating 3-dimensional structures. - The presented investigations clarify the physical background and the possibility to apply them for technical coatings. Besides the interaction of the magnetic forces and the geometric shape of the coating, the technological properties of the claddings are reported. The application of an external force made it possible to increase the efficiency of the laser cladding process and to gain more interest of the industry.
Entwicklung neuer Anwendungen und Prozesse zum Auftragschweißen mittels Simulation. - In: Neue Materialien und Verfahren in der Beschichtungstechnik, (2005), S. 267-275
DC thermal plasma CVD synthesis of coatings from liquid single source SiBCN and SiCNTi precursors. - In: Surface and coatings technology, ISSN 1879-3347, Bd. 200 (2005), 1/4, S. 612-615
DC plasma jet CVD is applied to synthesize coatings from liquid state single source precursors on metallic substrates. For SiBCN coating synthesis hexamethylcyclotrisilazanoboranes with Si/B ratio 3:1, 3:2 and 3:3 are used. SiCNTi coatings are produced with tris(dimethylamino)- and tris(diethylamino)hexamethylcyclotrisilazanotitanium. Attempts to deposit SiCNZr coatings by use of tris(diethylamino)hexamethylcyclotrisilazanozironium are not successful due to too high precursor viscosity. Vacuum plasma sprayed nickel, molybdenum and copper interlayers prove to permit effective suppression of nitride and boride reaction zone formation, which is observed during direct SiBCN coating deposition on mild steel substrates. By use of adapted process parameters coatings with columnar or dense morphology and amorphous or nanocrystalline structure can be synthesized. Deposition rates exceeding 2000 my m/h are achieved. By relative movement between DC plasma torch and substrate surface the coated area is enlarged. Simultaneous improvement of coating density and homogeneity is observed.
https://doi.org/10.1016/j.surfcoat.2005.01.027
Full mechanised cladding of 3-dimensional components in constraint position with the PPAW-process. - In: Conference proceedings, (2005), S. 896-901
Short-pulse laser post processing of PTA and thermal sprayed wear and corrosion resistant coatings. - In: Conference proceedings, (2005), S. 332-336
Supersonic nozzles for the wire arc spraying. - In: Conference proceedings, (2005), S. 1068-1073
Suitability of high power diode laser for plasma-augmented-laser-cladding (PALC). - In: Conference proceedings, (2005), S. 1279-1284
Laser cladding offers several advantages as low dilution, low thermal influence and distortion of the components and a fine microstructure due to the high cooling rate. Nevertheless the set of laser cladding in the industrial production is nowadays limited to few applications, as the efficiency of laser sources is still too low and the running costs are too high. The absorption behaviour of metal surfaces, as for example steel, towards diode laser (up to approx. 42%) is very high compared to Nd:YAG (approx. 35%) and CO2-Laser sources (approx. 11%), so that some benefits can be expected. One of the disadvantages of diode laser was the low intensity and the difficulty to couple it in a fibre. The development of the last years reached to overcome these boundaries. High power diode lasers are nowadays available till 6 kW and can be coupled in fibres, allowing an easier processing. Investigations regarding laser alloying with high power diode laser confirm the appreciable reliability of this laser class. In order to improve efficiency of laser surface processing the hybrid process plasma-augmented-laser-cladding (PALC) with an Nd:YAG laser source was presented and confirmed that due to the pre-heating of the powder through the plasma transferred arc and the activation of the metallic surface a higher processing velocity (factor three) and efficiency could be reached by summing only one third of the energy with a PTA-equipment. Further more when processing with higher velocity the energy loss due to conductivity decreases so that a further positive increase of efficiency can be depicted. The suitability of fibre coupled high power diode laser for PALC hasn’t yet been investigated, even if the set of this laser type would be very advantageous. - In this paper investigations regarding the process design and the necessary set up of the hybrid PALC-process with a 3 kW fibre coupled high power diode laser and wire coating metal are reported.
Influence of the voltage modulation frequency on voltage trace and coatings properties. - In: Conference proceedings, (2005), S. 393-398
Effective laser-cladding through the application of magnetic induced forces. - In: Conference proceedings, (2005), S. 1264-1269
In the last years laser beam cladding was recognised as a high quality coating process. Low thermal influence, high cooling rates, metallic bonding, minimal surface roughness are only some of the positive aspects. On the other hand the process efficiency is very low and the running costs in comparison with PTA or Thermal Spraying are high. Attempts to improve the productivity, aim to enhance the efficiency of the beam source itself or to optimize the energy management. This is for example possible through a higher coating speed or through hybrid setups, which allow the use of an additional preheat source (e. g. plasma-assisted laser cladding). Regarding flexibility, defined as the capability of a process to answer in a short time to application requests, the effectiveness of laser cladding can be widely increased through free forming (shaping) of coatings without additional clamping devices. The geometric shape of the coating seam is mainly defined by gravity and surface tension of the melt. An additional force, as for example Lorentz force, can optimize the geometry and improve the process conditions. Wide seams allow for example a low number of overlapping layers when coating large areas and rise the specific area deposition rate. Slim coatings on the contrary are advantageous when generating 3&Ohaak;dimensional structures. The induced force depends from the applied magnetic field and the flow of an electric current. The presented investigations clarify the physical background, the interaction of the magnetic force and the geometric shape of the coating and the possibility to apply them for technical coatings. The application of an external force made it possible to increase the efficiency of the laser cladding process and to gain more interest of the industry.