Influence of Gas Type on the Thermal Efficiency of Microwave Plasmas for the Sintering of Metal Powders

  • Aidan Breen
  • Vladimir Milosavljević
  • Denis P. Dowling
Original Paper


Microwave plasmas have enormous potential as a rapid and energy efficient sintering technology. This paper evaluates the influence of both plasma atmosphere and metal powder type on the sintering temperatures achieved and the properties of the sintered powder metal compacts. The sintering is carried out using a 2.45 GHz microwave-plasma process called rapid discharge sintering (RDS). The sintering of three types of metal powder are evaluated in this study: nickel (Ni), copper (Cu) and 316L stainless steel (SS). An in-depth study of the effects of the plasma processing parameters on the sintered powder compacts are investigated. These parameters are correlated with the mechanical performance of the sintered compacts to help understand the effect of the plasma heating process. The substrate materials are sintered in four different gas discharges, namely hydrogen, nitrogen oxygen and argon. Thermocouple, pyrometer and emission spectroscopy measurements were taken to determine the substrate and the discharge temperatures. The morphology and structure were examined using scanning electron microscopy and X-ray diffraction. The density and hardness of the sintered compacts were correlated with the plasma processing conditions. As expected higher densities were obtained with powders with lower sintering temperatures i.e. nickel and copper when compared with stainless steel. Under the power input and pressure conditions used, the highest substrate temperature attained was 1,100°C for Cu powder sintered in a nitrogen atmosphere. In contrast under the same processing conditions but in an argon plasma, the temperature achieved with SS was only 500°C. The effect of the plasma gas type on the sintered powder compact chemistry was also monitored, both hydrogen and nitrogen yielded a reducing effect for the metal in contrast with the oxidising effect observed in an oxygen plasma.


Microwave plasma Sintering Thermal measurements Emission spectroscopy 



This work is part supported by Science foundation Ireland 08/SRC/I1411. V. Milosavljevic is grateful to the Ministry of Science and Education of the Republic of Serbia (project No. 171006).


  1. 1.
    German R (1994) Metal Powder Industries Federation, USAGoogle Scholar
  2. 2.
    Clark D, Sutton W (1996) Annu Rev Mat Sci 26:299ADSCrossRefGoogle Scholar
  3. 3.
    Agrawal D (1998) Curr Opin Solid State Mater Sci 3(5):480ADSCrossRefGoogle Scholar
  4. 4.
    Wroe R (1999) Powder Metall (Special Feature) 54(7):24–28Google Scholar
  5. 5.
    Saitou K (2006) Scripta Mater 54:875–879CrossRefGoogle Scholar
  6. 6.
    Johnson D, Sanderson W, Knowlton J, Kemer E, Chen M-Y (1988) Advances in plasma sintering of alumina. Sci Sinter 20(2/3):109–113Google Scholar
  7. 7.
    Loureno J, Maliska A, Klein A, Muzart J (2004) Mater Res 7:269CrossRefGoogle Scholar
  8. 8.
    Twomey B, Breen A, Byrne G, Hynes A, Dowling D (2010) Metal Powder Rep 65(2):10CrossRefGoogle Scholar
  9. 9.
    Twomey B, Breen A, Byrne G, Hynes A, Dowling D (2011) J Mater Proc Technol 211(7):1210CrossRefGoogle Scholar
  10. 10.
    Bennett C, McKinnon N, Williams L (1968) Nature 217:1287ADSCrossRefGoogle Scholar
  11. 11.
    Chang C, Szekely J (1982) J Met 34(2):57Google Scholar
  12. 12.
    Zhu X, Chen W, Pu Y (2008) J Phys D Appl Phys 41:105212ADSCrossRefGoogle Scholar
  13. 13.
    Nersisyan G, Graham W (2004) Plasma Sour Sci Technol 13:582ADSCrossRefGoogle Scholar
  14. 14.
    Arkhipenko V, Kirillov A, Simonchik L, Zgirouski S (2005) Plasma Sour Sci Technol 14:757ADSCrossRefGoogle Scholar
  15. 15.
    Bluem E, Bechu S, Boisse-Laporte C, Leprince P, Marec J (1995) J Phys D Appl Phys 28:1529ADSCrossRefGoogle Scholar
  16. 16.
    Ricard A, Décomps P, Massines F (1999) Surf Coat Technol 112(1–3):1CrossRefGoogle Scholar
  17. 17.
    Ricard A, Gaillard M, Monna V, Vesel A, Mozetic M (2001) Surf Coat Technol 142:333CrossRefGoogle Scholar
  18. 18.
    McConnell M, Dowling D, Pope C, Donnelly K, Ryder A, O’Connor G (2002) Diam Relat Mater 11(3–6):1036CrossRefADSGoogle Scholar
  19. 19.
    Lee P (1998) ASM handbook, vol 7, Powder metal technologies and applications. ASM International, Materials ParkGoogle Scholar
  20. 20.
    Ralchenko Y, Kramida A, Reader J, Team N (2008) National Institute of standards and technology, GaithersburgGoogle Scholar
  21. 21.
    Coburn J, Chen M (1980) J Appl Phys 51(6):3134ADSCrossRefGoogle Scholar
  22. 22.
    Popović D, Milosavljević V, Daniels S (2007) J Appl Phys 102:103303ADSCrossRefGoogle Scholar
  23. 23.
    Majstorović G (2008) In: 24th summer school and international symposium on the physics of ionized gases, Novi Sad, Serbia, 25–29 August 2008Google Scholar
  24. 24.
    Fantz U, Heger B (1998) Plasma Phys Control Fus 40:2023ADSCrossRefGoogle Scholar
  25. 25.
    Milosavljević V, Ellingboe RA (2004) PRL Internal report. Dublin City University, DublinGoogle Scholar
  26. 26.
    Breen A, Twomey B, Byrne G, Dowling D (2011) Mater Sci Forum 672:289CrossRefGoogle Scholar
  27. 27.
    Lee C, Graves D, Lieberman M, Hess D (1994) J Electrochem Soc 141:1546CrossRefGoogle Scholar
  28. 28.
    Griffiths D, College R (1999) Introduction to electrodynamics. vol 3, Prentice Hall, New JerseyGoogle Scholar
  29. 29.
  30. 30.
    Röpcke J, Käning M, Lavrov B (1998) Le Journal de Physique IV 8(PR7):207CrossRefGoogle Scholar
  31. 31.
    NIST-Atomic Spectra Data Base Lines (wavelength order) (2011)Google Scholar
  32. 32.
    Fantz U (1998) Plasma Phys Control Fus 40:1035ADSCrossRefGoogle Scholar
  33. 33.
    Milosavljević V, Poparić G (2001) Phys Rev E 63(3):036404ADSCrossRefGoogle Scholar
  34. 34.
    Herzberg G (1950) Molecular spectra and molecular structure, vol I. Van Nostrand-Reinhold, New YorkGoogle Scholar
  35. 35.
    Phillips J (1961) In: Optical spectrometric measurements of high temperatures, vol 1, p 217Google Scholar
  36. 36.
    Milosavljević V, Faulkner R, Hopkins MB (2007) Optics Express 15(21):13913ADSCrossRefGoogle Scholar
  37. 37.
    Nwankire C, Law V, Nindrayog A, Twomey B, Niemi K, Milosavljević V, Graham W, Dowling D (2010) Plasma Chem Plasma Process 30(5):537CrossRefGoogle Scholar
  38. 38.
    AZOM (2011) A to z of materials.
  39. 39.
    Komeya K, Inoue H (1969) J Mater Sci 4(12):1045ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Aidan Breen
    • 1
  • Vladimir Milosavljević
    • 2
    • 3
  • Denis P. Dowling
    • 1
  1. 1.School of Mechanical and Materials EngineeringUniversity College DublinDublinIreland
  2. 2.School of Physics and NCPSTDublin City UniversityDublinIreland
  3. 3.Faculty of PhysicsUniversity of BelgradeBelgradeSerbia

Personalised recommendations