Process development and properties of copper components fabricated via SEBM Zentralinstitut für Neue Materialien und Prozesstechnik Friedrich-Alexander-Universität Erlangen-Nürnberg Dr.-Ing. Matthias Lodes Ralf Guschlbauer, M. Sc. Prof. Carolin Körner EBAM, Nürnberg, 28. April 2016
Motivation copper exhibits excellent thermal (~ 400 W/mK) and electrical (~ 58 MS/m) conductivity possible application for efficient heat exchangers or micro reactors no stable additive process for fully dense pure copper parts available process development for SEBM evaluation of properties
Outline SEBM processing of pure copper Properties of SEBM-Cu SEBM processing of oxide dispersion strengthened copper
Experimental SEBM-setup Arcam A2 Manual process control Pure copper start plate 150 mm x 180 mm p = 2 10-3 mbar He
Volume Density [%] Cumulative Volume [%] Raw material: pure copper powder Pure copper pure gas atomized copper powder (99.94 %) nitrogen gas atomized particle size 45 µm - 105 µm good sphericity, some ligaments, small fine fraction main contaminants P, O Volume Density [%] Cumulative Volume [%] TIGA Cu-powder 25 20 15 10 5 0 0 100 200 Size Classes [µm] 120 100 80 60 40 20 0
Process stability Development of stable preheating smoking is no problem high sintering tendency swelling during raking low build temperature < 400 C cooling steps necessary
micrograph build direction top view Process window for fully dense components Surface and density Porous (energy too low) Dense Porous (energy too high) 5 mm 500 µm
Process window for fully dense components Process map volume energy density 20 80 J/mm³; layer thickness 50 µm dense samples for E V > 55 J/mm³
Pure copper samples and components Massive parts Cellular structures Reactor geometries Mechanical testing samples 10 mm 50 mm 10 mm 20 mm
Properties of SEBM-copper Mechanical properties Young's modulus [GPa] Yield strength [N/mm²] Tensile strength [N/mm²] Fracture strain [%] Hardness [HV0.05] 97.6 ± 4.6 93.7 ± 0.8 222.9 ± 1.5 60.4 ± 3.2 60.5 ± 7.2
Properties of SEBM-copper Electrical and thermal conductivity eddy current measurement laser flash analysis
Properties of SEBM-copper Electrical and thermal conductivity contamination heavily influences conductivity phosphorous seems to have main influence powder O [wt%] P [wt%] 1 0.04 0.02 2 0.02 0.06 3 0.01 0.08
Properties of SEBM-copper Wiedemann-Franz relation build direction
ODS-Cu raw material Mechanically alloyed powder ODS-Cu powder (5 vol% Al 2 O 3 ) particle size 43 µm - 113 µm chemo-mechanically alloyed more spattered shape no typical SEBM powder Pure-Cu ODS-Cu (5 vol.-% Al 2 O 3 ) Bulk density g/cm³ 4.63 ± 0.005 3.11 ± 0.007 Tap density g/cm³ 5.24 ± 0.03 3.55 ± 0.07 Flow time s/g 0.50 ± 0.001 0.83 ± 0.003 Oxygen content wt.-% 0.2 2.1
Processing of ODS-Cu Bad process stability No smoking Heavy degassing and sparkling Higher energy input necessary (process T > 650 ) Oxide layer inhibits sintering [Schmidt-Whitley]
Build direction Processing of ODS-Cu Sample fabrication Sample geometries could be fabricated mesostructure seems to show channel-like porosity 10 mm
Processing of ODS-Cu Microstructure 10 µm Black regions are no pores! Pure Al 2 O 3 and Cu formed Heavy demixing
Summary Pure copper can be fabricated successfully via SEBM High electrical (56 MS/m) and thermal (400 W/mK) conductivity Conductivities are heavily influenced by small contaminations ODS-copper demixes completely during processing Outlook: Alloy with higher strength More detailed investigation of mechanisms influencing conductivity
Thanks for your attention Guschlbauer, R. Pobel, C. Raab, S. Warmuth, F.