Desgaste y Corrocion

March 26, 2018 | Author: MIGUEL MEJIA | Category: Wear, Corrosion, Materials Science, Materials, Chemical Product Engineering


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Univ.-Prof. Dr.-Ing. habil. B. Wielage Prof. Dr.-Ing. habil. S.Steinhäuser Institute of Composite Materials Dr.-Ing. Th. Lampke. Chemnitz University of Technology Deposition welding of different layers and complex characterization of wear and corrosion properties Th. Lampke, S. Steinhäuser, B. Wielage Chemnitz University of Technology, Institute of Composite Materials and Surface Technology in cooperation with A. Gebert1, D. Wocilka1, F. Riedel2, K. Alaluss2 1) CeWOTec Ltd. (Chemnitz Materials and Surface Technology) 2) Chemnitz University of Technology, Institute of Welding Structure: • motivation for use of high-carbide containing layers • welding technology • characterization methods • wear tests • corrosion tests • wear-corrosion-tests 1 • summary Univ.-Prof. Dr.-Ing. habil. B. Wielage Prof. Dr.-Ing. habil. S. Steinhäuser Institute of Composite Materials Dr.-Ing. Th. Lampke. Chemnitz University of Technology Initial situation • risen requirements for construction units in the chemical industry and for offshore applications regarding wear and corrosion resistance • high costs resulting from application of corrosion proof steels and non ferrous alloys with insufficient corrosion resistance • today's high-wear-steady materials have insufficient corrosion resistance and tend to act brittle with rising carbide content 2 Univ.-Prof. Dr.-Ing. habil. B. Wielage Prof. Dr.-Ing. habil. S. Steinhäuser Institute of Composite Materials Dr.-Ing. Th. Lampke. Chemnitz University of Technology Aim of research Development of coating materials on iron basis for the plasma powder deposition-welding showing • high wear-resistance in connection with a • sufficiently high corrosion resistance and • assurances of high quality welding processing Characterization and qualification of high-carbide-containing wear protective coatings regarding the application under 3 strongly corrosive conditions as well as corrosion resistance Univ.-Prof. Dr.-Ing. habil. B. Wielage Prof. Dr.-Ing. habil. S. Steinhäuser Institute of Composite Materials Dr.-Ing. Th. Lampke. Chemnitz University of Technology Plasma-powder-deposition-welding Powder feedstock Plasma gas Shielding gas Power source Power source Substrate • Flexibility regarding the deposition materials and construction unit geometry • Even and reproducible deposition quality 4 • Small heat input into the construction unit • Layer thicknesses between 1 and 5 mm per layer 4021 (X20Cr13) • Austenitic steel: 1.4404 (X5CrNiMo17-12-2) • Duplex steel: 1.-Ing. 60 % . Dr. 45 %. carbide contents 30 – 60 %) . 45 %. Steinhäuser Institute of Composite Materials Dr.Fe-CrV 15 + 30% VC maraging / • Super-duplex-steel + VC austenitic 30 %.-Ing.Fe-CrV 15 maraging and austenitic 30 %. habil.4462 (X2CrNiMoN22-5-3) Matrix Alloys Base line materials Test materials • Iron-based alloys • Austenitic steel + VC . Univ. 60 % • Co basis alloys: Stellite 6 and 12 • Ni based alloys.: Inconel 625 + 30 % VC Strengthening phase 5 • Vanadium carbide (VC is decay resistant.-Ing. Th. Dr.-Prof. B. Substrates and deposition materials Chemnitz University of Technology Substrates (thickness of blank sheet 8 and 10 mm) • Steel: 1. S. Wielage Prof. habil. Lampke. 20 % fluids) • Potentio-dynamic measurements (point-like examination) • Agitation test according to DIN 50905 / 4 • Long-term corrosion test without substrates • Miller Test according to ASTM G75-01 (combined test abrasion / corrosion) Testing media • artificial sea water (DIN 50905 / 4) • 30 % citric acid • 20 % sulfuric acid 6 • 30 % acetic acid (only tested at Fe-CrV 15) . habil. Steinhäuser Institute of Composite Materials Dr. habil. Wielage Prof.-Ing. B. Lampke. Dr.-Ing. Univ. Dr. Th. Chemnitz University of Technology Testing methods and media Testing methods • Sandpaper test (abrasive wear test) • Wear pot (point-like examination. S. 80 % solids.-Ing.-Prof. SEM and EDXS • Determination of materials removal caused by corrosion and abrasion • Investigation of the influence of the phase boundaries carbide / matrix on the corrosion resistance in connection with abrasive wear (identification procedure) • Assessment of corrosion and wear manifestation • Optimizations of the material and powder variants as well as welding parameters 7 . welding bead forming etc. Wielage Prof. habil. Dr.-Prof. Dr.-Ing. Chemnitz University of Technology Main points of investigation • Determination of layer characteristics (e. micro-structure.) by means of optical microscopy. Univ.g. imperfections. S.-Ing. B.-Ing. Th. Steinhäuser Institute of Composite Materials Dr. Lampke. hardness. habil. carbide distribution. Dr. Th. B.austenitic 8 without and with 30 % VC . Univ. Wielage Prof.-Ing.-Ing. habil. Chemnitz University of Technology Sample manufacturing from welded parts Samples without substrate to be used for long term corrosion tests Specimens (substrate and layer) Samples: Fe-CrV 15 . S. Lampke. habil.-Prof.-Ing. Dr. Steinhäuser Institute of Composite Materials Dr. Wielage Prof.-Ing. habil.-Ing.3. B. habil. Dr.-Prof. Univ.-Ing.47 µm (cross) / 1. Th. S. Chemnitz University of Technology Sample manufacturing by means of jet cutting Inconel 625 + 30 % VC Specimens to be used for Miller tests Specimens to be used for long- term agitation Specimens tests and to be used wear pot for tests sandpaper tests and potentio- dynamic tests 9 Final roughness: Rz = 4.82 .37 .9.23 µm (longitudinal) . Dr. Lampke. Steinhäuser Institute of Composite Materials Dr. habil. Dr. steel + 60 % VC Fe-CrV15-m + 30 % VC 10 S. Th. Steinhäuser Institute of Composite Materials Dr.-Ing.-duplex steel + 60 % VC Stellite 6 (etched) .-Ing. Univ. habil. Wielage Prof. B. S.-Ing. Dr. Lampke.-Prof. Chemnitz University of Technology Characterization of the microstructure Samples (investigated before corrosion and wear tests) aust. Steinhäuser Institute of Composite Materials Dr.-Ing. Wielage Prof.-Prof. habil. Dr.-Ing. S. B. habil. Univ. Lampke.-Ing. Chemnitz University of Technology Hardness course of deposition welded materials surface 11 substrate . Th. Dr. habil. B. habil. With regard to the work piece that has to be manufactured. wear processes can also be technically desired. Steinhäuser Institute of Composite Materials Dr.-Ing. Dr. S. Comment: a) The application of stress on the surface of a solid body through contact and relative movement of a solid.e. wear is normally not desired. in exceptional cases such as running-in processes. Chemnitz University of Technology Tribology Definition Wear [DIN 50 320] Wear is the progressive material loss on the surface of a solid body.-Ing. it reduces the value of a material.-Prof. . Wielage Prof. i. although tribological processes similar to that during 12 wear take place in the interfacial region between working piece and tool. fluid or gaseous counterbody. contact and relative movement of a solid. Lampke. However.e. caused by mechanical reasons.-Ing. fluid or gaseous counterbody is called tribological load. Th. b) Wear is expressed by the occurrence of removal of small particles (wear debris) as well as changes in material and shape of tribologically stressed surface layer. Dr. i. c) In practice. value-improving technological treatment processes are not seen as wear. Univ. Dr. wear products. Th. Univ. S. habil. Dr. Wielage Prof. B. Steinhäuser Institute of Composite Materials Dr.-Ing. Chemnitz University of Technology Tribology Circumstances of motion Load Operating variables State of friction Temperature Conditions of contact Microgeometry Counter body Structure of the Surround medium tribosystem Material Body m . Lampke. habil.-Ing.8 0 a tw e Interfacial medium Wear process Loss of material (wear quantity.-Prof. wear debris) [DIN 50320] 13 Wear characteristics Wear phenomena (surface change) Change of properties .-Ing. -Ing.-Ing. Dr. Dr. Univ. Chemnitz University of Technology Wear mechanisms different wear mechanisms cause changes in mass or volume through formation of transfer of wear material particles influencing the material removal core material superimposed chemical 14 reactions . habil. B. Lampke. S.-Ing. Wielage Prof. Steinhäuser Institute of Composite Materials Dr.-Prof. habil. Th. fretting wear test . oscillation wear test . Chemnitz University of Technology Tribological tests Tribological testing chain Characterization of tribology materials behaviour Testing methods for Tests by integral Investigation of tribolo- simulation of basic wear test methods Simulation of technical gical relevant material wear systems properties . S.abrasive wear . chemical composition . Dr. texture .drawing . grain size 10 8 6 4 test in practice 2 0 15 . B. adherence of coatings .driving gear .adhesive wear .-Ing. Steinhäuser Institute of Composite Materials Dr.-Ing. Tabor-Abraser test . hardness .stretching rolls . state of stress . erosive wear test . habil.-Prof.-Ing. Lampke. Univ. Wielage Prof.long time fatigue wear . Dr. Th. sliding wear test . habil. S.-Prof. B. Univ. Wielage Prof. habil.-Ing. Dr.-Ing.-Ing. Chemnitz University of Technology Tribology breakout state of persistence running-in phase time / path 16 High demand for extended „state of persistence“ . Th. habil. Dr. Steinhäuser Institute of Composite Materials Dr. Lampke. Univ. B. Dr.-Ing. habil.-Ing.-Prof. S. Dr. Wielage Prof. Chemnitz University of Technology Sandpaper test Test surface: 1 cm² Test duration: 20 s Media: water SiC paper: grain size 180 Test load: 30 N Test velocity: 86 m/min ro tie re n d e s Rotating N a ß s c h l esandpaper ifp a p ie r F Specimen P ro b e n - W a s s e r. habil. retainer h a lte r zWater u flu ß f Coated e s ts te h e n d e P ro b e m it B e - Grinding S c h le if g e s cvelocity: h w in d ig k e it : sspecimen c h ic h tu n g 8 6 m / m in a 17 86 m/min . Th. Steinhäuser Institute of Composite Materials Dr.-Ing. Lampke. S. Lampke. Dr.-Ing. habil. B. Th.-Ing. Dr. Univ. Wielage Prof.-Ing. Chemnitz University of Technology Results of sandpaper test (abrasive wear) Hardness [HRC] Volume loss [mm³/min cm²] Volume loss [mm³/min cm²] Hardness [HRC] 18 .-Prof. habil. Steinhäuser Institute of Composite Materials Dr. -Ing. Chemnitz University of Technology Definition of corrosion Corrosion is the reaction of a metallic material with its environment. S. In the most cases this reaction is of electro-chemical nature. Th. Steinhäuser Institute of Composite Materials Dr. Dr. Dr. however in some cases corrosion can be of chemical or metal-physical nature. habil.-Ing. Wielage Prof.-Ing. habil. which lead to a measurable change of the material and to the impairment of the function of a metallic construction unit or a whole system. Univ. Reactions of non-metallic materials are not the subject of this standard. B. 19 .-Prof. Lampke. However the fundamental ideas defined here can be transferred in a general manner to other materials. Dr. Th. habil. Lampke. many problems have to be taken into consideration . Steinhäuser Institute of Composite Materials Dr.-Ing. Dr. Chemnitz University of Technology Corrosion test chain (in accordance with DIN 50 900) 20 In order to evaluate the corrosion behaviour. Wielage Prof. habil. B.-Ing. S.-Ing.-Prof. Univ. -Ing. Chemnitz University of Technology Long-term corrosion test Test conditions • Tests at deposited materials (69. habil.-Prof. Dr.-Ing.-Ing. Lampke. habil. Dr. Th.6 mm) • Unaffected specimens • Duration: 3 x 168 h (sum: 504 h which is 3 weeks) 1 x 168 h (20 % H2SO4) • Room temperature • Surface in total: ~25cm2 • 0. B. Univ. S. Wielage Prof.0 x 15.5 l corrosion media • No change of corrosion media during the test 21 . Steinhäuser Institute of Composite Materials Dr.0 x 4. 45-Stellite 6) (38/41/44-Duplex. habil. Th. Chemnitz University of Technology Long-term corrosion test 38 41 44 47 Corrosion attack by means of artificial Corrosion attack by means of sea water after 504 h sulfuric acid (20 %) after 168 h 22 (36/39/42-Duplex. Steinhäuser Institute of Composite Materials Dr.-Ing. Wielage Prof.-Ing. Lampke. Dr. Univ.-Prof. 47-Stellite 6) . B.-Ing. Dr. S. habil. -Ing.-Ing. Dr. habil. S. Univ. Lampke. Th. habil.-Prof. Chemnitz University of Technology Long-term corrosion test 25 % acetic acid artificial sea water 30 % citric acid 20 % sulfuric acid Volume loss [mm³/ 504 h 25 cm²] Volume loss [mm³/ 168 h 25 cm²] 23 Content of carbides: 38-40 Vol-% VC 63-68 Vol-% VC . Wielage Prof.-Ing. Dr. B. Steinhäuser Institute of Composite Materials Dr. Dr.-Ing. Steinhäuser Institute of Composite Materials Dr.-Ing. Dr. Wielage Prof.-Ing. habil. B. Univ. Th. Chemnitz University of Technology Long-term corrosion test artificial sea water Corrosive mass loss compared to 20 % sulfuric acid 30 % citric acid Scale for 20 % sulfuric acid Iron-based steel: > 700 in citric acid Stellite 6 (Stellite 6 = 1) 24 Content of carbides: 38-40 Vol-% VC 63-68 Vol-% VC .-Prof. habil. Lampke. S. Lampke. S. Steinhäuser Institute of Composite Materials Dr. B. Dr.and intergranular attack .-Prof. habil. Th.-Ing./ micro-structure of Super Duplex steel + 60 % VC Artificial sea water Citric acid (30 %) Sulfuric acid (20 %) 25 ⇒ trans.-Ing. Wielage Prof. Univ. Chemnitz University of Technology Long-term corrosion test macro. habil. Dr.-Ing. Dr. habil. Steinhäuser Institute of Composite Materials Dr.-Ing. Lampke. Dr. S. manifestations depending on corrosion media . habil. Chemnitz University of Technology Long-term corrosion test SEM of Super Duplex steel + 60 % VC Sulfuric acid (20 %) Citric acid (30 %) 26 ⇒ Corroded surfaces. B.-Prof.-Ing. Univ. Wielage Prof.-Ing. Th. Chemnitz University of Technology Potentiodynamic measurements Technische Universität Ch • Working range: -600 mV until +2000 mV • Polarization velocity: 0. Dr. B. Univ.-Prof. Wielage Prof. Lampke. habil.5 mV/s • Investigation of open circuit potential (30 min) • Estimation of corrosion manifestations Potentiostat PS6 with measuring cell • Platin. Steinhäuser Institute of Composite Materials Dr.-Ing. S.-Ing. Th. RE) • Metallographic preparation required 27 • Electrolyte selectable . habil.-Ing.and Calomel electrode (CE. Dr. mart.-Ing. Chemnitz University of Technology Potentiodynamic measurements Artificial sea water 3 2 Current density [mA/cm²] log 1 0 -1000 -500 0 500 1000 1500 2000 -1 Fe-Cr-V-C. Steinhäuser Institute of Composite Materials Dr. Th. Univ. habil. Dr. Steel + 60 % VC 7-M2 7-M3 -4 Stellite 12 9-M2 9-M3 -5 Super-Duplex-Steel + 60 % VC 13-M2 13-M3 -6 Potential [mV] 28 Outstanding corrosion resistance of Stellite 12 (current / potential) . Wielage Prof.-Ing. Lampke.-Ing. B. + 30 % VC -2 2-M2 2-M3 -3 aust. S.-Prof. habil. Dr. B. S. Steel + 60 % VC 0 7-S2 -1000 -500 0 500 7-S3 1000 1500 2000 -1 7-S4 Stellite 12 9-S2 -2 9-S4 Super-Duplex-Steel + 60 % VC -3 13-S2 13-S3 13-S4 -4 Potential [mV] 29 Outstanding corrosion resistance of Stellite 12 (current / potential) !! .-Ing. habil. Chemnitz University of Technology Potentiodynamic measurements 20 % H2SO4 Strong reactions at WE and CE 5 4 3 Current density [mA/cm²] log 2 1 aust.-Ing. Lampke. Steinhäuser Institute of Composite Materials Dr. Th. Dr. Dr. habil.-Prof. Wielage Prof.-Ing. Univ. Wielage Prof. mart.-Ing. Steel + 60 Super-Duplex- 4000 H2SO4 % VC Stellite 12 Steel + 60 % VC Current density [µA/cm²] 3500 -260 3000 2869 Open circuit potential [mV] -270 2500 2000 -280 -275 1500 1000 -290 500 54 -300 -297 0 -301 30 aust. -310 % VC Steel + 60 % VC . habil.06 Current density [µA/cm²] C.18 -400 -344 0 -374 Fe-Cr-V-C. Current density / Open circuit potential Super- Chemnitz University of Technology 10 9 9 Fe-Cr-V. + 30 % 60 % VC Duplex-Steel VC + 60 % VC 4500 4122 aust. + aust. S. Dr. Steel Steel + 60 Open circuit potential [mV] 8 30 % VC + 60 % VC Stellite 12 % VC 7 6 sea water 0 5 -100 4 3 -200 3 2 -300 1 -282 0. B. Steel + Stellite 12 Super. Dr. Lampke.-Ing. -500 -460 mart. Duplex- Artificial 8. aust. Steinhäuser Institute of Composite Materials Dr. Steel + 60 Stellite 12 Super-Duplex. Th.-Prof.-Ing. habil. Univ. Wielage Prof. habil.4462 . Th. Steinhäuser Institute of Composite Materials Dr. Dr.4404 31 1. S. Dr.4021 1. Univ.-Ing. Chemnitz University of Technology Salt spray test 96 h exposure time.-Prof. Lampke. habil. B.-Ing. 5 % NaCl Stellite 12 Fe-CrV15 (mart.-Ing.) Super-Duplex-Steel Austenitic steel + 60 % VC + 60 % VC 1. 8 29 26 20 7.-Ing.4 32 0 1 3 7 8 10 13 13‘ . Univ.4404) 8 Stellite 12 (1. Chemnitz University of Technology Salt spray test Substrates 132 Mass loss [mg] 150 100 50 7 6 1 Fe-CrV15 mart. Lampke.4021 1. Dr.4462) 13‘ dito 74. Th. habil.4462) 10 Inconel 625 + 30 % VC (1. Wielage Prof.-Ing. Dr. B.-Duplex-Stahl + 60 % VC (1. S.6 Mass loss [mg] 80 60 40 22.4404) 1. (1. habil. (1.-Ing.-Prof.4404) 13 S.7 23. Steinhäuser Institute of Composite Materials Dr.8 7.4462 7 Fe-CrV15l + 60 % VC (1.4021) 0 3 Fe-CrV15 aust.4404 1. Dr.-Ing. Th. Steinhäuser Institute of Composite Materials Dr. Univ. habil.-Ing. Lampke. Dr. S.-Ing. habil. Wielage Prof. Chemnitz University of Technology Preparative influence on the corrosion behavior 0 Current density [mA/cm²] -1 etched -2 log -3 -4 W-D 2/2-5 T-D 2/1-1 -5 A-D 2/3-1 as received -6 -700 -500 -300 -100 Potential [mV] • etching of the samples with HCl ⇒ surface activated ⇒ higher corrosion currents 33 ⇒ shift of the corrosion potential towards negative stresses . B.-Prof. Dr. habil. S.-Ing. Th. habil. Chemnitz University of Technology Preparative influence on the corrosion behavior 2 Al2O3 Al2O3 1 TiO2 TiO2 without particles without particles 0 SiC (micro) Ni compact IKorr (log) [mA/cm²] -1 -2 -3 -4 -5 not grinded grinded -6 -600 -400 -200 0 200 400 Potential [mV] • mechanical grinding of the samples ⇒ lower corrosion currents 34 ⇒ shift of the corrosion potential towards lower voltage .-Prof.-Ing. Lampke. Wielage Prof. Univ. B.-Ing. Steinhäuser Institute of Composite Materials Dr. Dr. S. Th.-Ing.-Ing. Dr.-Ing. Wielage Prof. habil.4 x 12. B. Chemnitz University of Technology Complex wear test Miller test Load: 22.24 N Advantages: • Complex corrosion / wear test (in situ) • Free choice of abrasives and media • Easy to handle and to determine Wear path: 200 mm (oscillating) 20 m/min Duration: 4 x 2 h Dimensions of specimens 25. habil.7 mm Abrasive suspension 35 150 g Al2O3 + 150 ml corrosive media . Dr. Univ.-Prof. Steinhäuser Institute of Composite Materials Dr. Lampke. -Ing. Univ.-Ing. Th. Dr.-Prof. Chemnitz University of Technology Results of abrasive wear tests Mass loss caused by sandpaper test (sandpaper test / Miller test) Mass loss caused by Miller test Mass loss caused by sandpaper test + water [mg/min cm²] Mass loss caused by Miller test + water [mg/8 h] 36 ⇒ Good qualitative agreement of both test methods . habil. S. B. Steinhäuser Institute of Composite Materials Dr. habil. Wielage Prof. Lampke. Dr.-Ing. Dr. Steinhäuser Institute of Composite Materials Dr. Th. habil. Lampke.-Ing. B. Univ. habil.-Prof.-Ing. S.-Ing. Dr. Chemnitz University of Technology Results of abrasive wear tests (sandpaper test / Miller test) 25 % acetic acid artificial sea water 30 % citric acid distilled water Mass loss [mm³/8 h] 20 % sulfuric acid (only for high carbide contents 37 Content of carbides: 38-40 Vol-% VC 63-68 Vol-% VC . Wielage Prof. -Ing. Dr. B.-Prof. Lampke. S. habil. Steinhäuser Institute of Composite Materials Dr. Dr. Univ. Chemnitz University of Technology Results of abrasive wear tests (sandpaper test / Miller test) 30 % citric acid artificial sea water Improvement related to Stellite 12 20 % sulfuric acid distilled water 38 Content of carbides: 38-40 Vol-% VC 63-68 Vol-% VC .-Ing. Th.-Ing. habil. Wielage Prof. Wielage Prof.-Prof. Dr. Dr. B. habil. Th. S.-Ing. Univ.-Ing. Lampke. Steinhäuser Institute of Composite Materials Dr. Chemnitz University of Technology Results of abrasive wear tests (sandpaper test / Miller test) 30 % citric acid artificial sea water 20 % sulfuric acid 30 % acetic acid Mass loss related to corrosion in % Scale for artificial sea water 39 Content of carbides: 38-40 Vol-% VC 63-68 Vol-% VC .-Ing. habil. -Ing. Dr. Th. Univ. Lampke. Wielage Prof. habil.-Ing. B.-Ing. desired materials on Fe-basis (even with higher VC content) possess excellent abrasive wear characteristics with sufficient corrosion resistance • Mass loss is mainly related to abrasive wear effects • Carbide contents up to 50 % can be realized economically in combination with the desired materials on Fe-basis to ensure suitable properties 40 .-Prof. Chemnitz University of Technology Summary • Particles distribution can be described as suitable by means of layer welding • Embrittlement of characterized with rising carbide content was not detected • depending on corrosive agent. S. Dr. Steinhäuser Institute of Composite Materials Dr. habil. -Ing. Dr. Steinhäuser Institute of Composite Materials Dr.-Ing. Th.-Prof. S. habil. habil. Dr. Chemnitz University of Technology Summary • one test method is not sufficient for the characterisation of the corrosion behaviour ⇒ e. Univ. Lampke.-Ing. B. Wielage Prof. current density potential curves + assessment of the corrosion manifestation • preparative influence on the test results should not be underestimated • Development of coating materials on iron basis for the plasma powder deposition-welding was successful showing high wear-resistance in connection with a sufficiently high corrosion resistance and assurances of high quality welding 41 processing .g. Univ.-Ing. sea waters) • Waste product preparation (waste water. Dr. habil. Steinhäuser Institute of Composite Materials Dr. Wielage Prof. Dr. valves. parts of gears) • Offshore technology (water-oil-sand mixtures. Chemnitz University of Technology Potential of application • Active and passive construction units (pumps. Lampke. Th. grinding mill parts. habil.-Ing. sewage sludge) • Chemical industry • Foodstuffs industry 42 . stabilizers.-Prof. S. decanter. B.-Ing. -Ing. Dr.-Ing. habil. Univ. S. Chemnitz University of Technology The authors would like to thank the „Working Group of Industrial Research Associations“ for the financial support of the research as well as all the colleagues who have contributed to this project for their constructive cooperation. Lampke. Wielage Prof. Steinhäuser Institute of Composite Materials Dr.-Ing. Th. habil. Thank you very much for your kind attention! 43 .-Prof. B. Dr.
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