Process development and properties of copper components fabricated via SEBM

Transcription

1 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

2 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

3 Outline SEBM processing of pure copper Properties of SEBM-Cu SEBM processing of oxide dispersion strengthened copper

4 Experimental SEBM-setup Arcam A2 Manual process control Pure copper start plate 150 mm x 180 mm p = mbar He

5 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 µm good sphericity, some ligaments, small fine fraction main contaminants P, O Volume Density [%] Cumulative Volume [%] TIGA Cu-powder Size Classes [µm]

6 Process stability Development of stable preheating smoking is no problem high sintering tendency swelling during raking low build temperature < 400 C cooling steps necessary

7 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

8 Process window for fully dense components Process map volume energy density J/mm³; layer thickness 50 µm dense samples for E V > 55 J/mm³

9 Pure copper samples and components Massive parts Cellular structures Reactor geometries Mechanical testing samples 10 mm 50 mm 10 mm 20 mm

10 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 ± ± ± ± ± 7.2

11 Properties of SEBM-copper Electrical and thermal conductivity eddy current measurement laser flash analysis

12 Properties of SEBM-copper Electrical and thermal conductivity contamination heavily influences conductivity phosphorous seems to have main influence powder O [wt%] P [wt%]

13 Properties of SEBM-copper Wiedemann-Franz relation build direction

14 ODS-Cu raw material Mechanically alloyed powder ODS-Cu powder (5 vol% Al 2 O 3 ) particle size 43 µm 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 ± ± Tap density g/cm³ 5.24 ± ± 0.07 Flow time s/g 0.50 ± ± Oxygen content wt.-%

15 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]

16 Build direction Processing of ODS-Cu Sample fabrication Sample geometries could be fabricated mesostructure seems to show channel-like porosity 10 mm

17 Processing of ODS-Cu Microstructure 10 µm Black regions are no pores! Pure Al 2 O 3 and Cu formed Heavy demixing

18 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

19 Thanks for your attention Guschlbauer, R. Pobel, C. Raab, S. Warmuth, F.