Editing Sintering (section)

=== Spark plasma sintering ===
In [[spark plasma sintering]] (SPS), external pressure and an electric field are applied simultaneously to enhance the densification of the metallic/ceramic powder compacts. However, after commercialization it was determined there is no plasma, so the proper name is spark sintering as coined by Lenel. The electric field driven densification supplements sintering with a form of hot pressing, to enable lower temperatures and taking less time than typical sintering.<ref name = Tuan>{{Cite book|last1 = Tuan|first1 = W.H.|last2 =Guo|first2 =J.K.|publisher =Springer|year = 2004 |isbn = 3-540-40516-X|title = Multi-phased ceramic materials: processing and potential}}</ref> For a number of years, it was speculated that the existence of sparks or plasma between particles could aid sintering; however, Hulbert and coworkers systematically proved that the electric parameters used during spark plasma sintering make it (highly) unlikely.<ref>{{cite journal | last1 = Hulbert | first1 = D. M. | display-authors = etal | year = 2008 | title = The Absence of Plasma in' Spark Plasma Sintering' | doi = 10.1063/1.2963701 | journal = Journal of Applied Physics | volume = 104 | issue = 3| pages = 033305–033305–7 | bibcode = 2008JAP...104c3305H | s2cid = 54726651 | url = http://www.escholarship.org/uc/item/2c14z63t }}</ref> In light of this, the name "spark plasma sintering" has been rendered obsolete. Terms such as field assisted sintering technique (FAST), electric field assisted sintering (EFAS), and direct current sintering (DCS) have been implemented by the sintering community.<ref>Anselmi-Tamburini, U. et al. in Sintering: Nanodensification and Field Assisted Processes (Castro, R. & van Benthem, K.) (Springer Verlag, 2012).</ref> Using a [[direct current]] (DC) pulse as the electric current, spark plasma, spark impact pressure, joule heating, and an electrical field diffusion effect would be created.<ref name=Palmer>{{Cite book|last1 = Palmer|first1 = R.E.|last2 = Wilde|first2 = G.|title = Mechanical Properties of Nanocomposite Materials|publisher = Elsevier Ltd.|date = December 22, 2008|location =EBL Database|isbn = 978-0-08-044965-4}}</ref> By modifying the graphite die design and its assembly, it is possible to perform [[pressureless sintering]] in spark plasma sintering facility. This modified die design setup is reported to synergize the advantages of both conventional pressureless sintering and spark plasma sintering techniques.<ref>{{cite journal
|author=K. Sairam |author2=J.K. Sonber |author3=T.S.R.Ch. Murthy |author4=A.K. Sahu |author5=R.D. Bedse |author6=J.K. Chakravartty
|title=Pressureless sintering of chromium diboride using spark plasma sintering facility
|journal=International Journal of Refractory Metals and Hard Materials
|year=2016 |volume=58 |pages=165–171
|doi=10.1016/j.ijrmhm.2016.05.002
}}</ref>