Advances in Nanocarbon Metals: Process

Transcription

1 ARL-CR-0763 MAR 2015 US Army Research Labratry Advances in Nancarbn Metals: Prcess by P Chris Pistrius and Pengcheng Yan Carnegie Melln University 5000 Frbes Avenue Wean Hall 4313 Pittsburgh, PA Apprved fr public release; distributin is unlimited.

2 NOTICES Disclaimers The findings in this reprt are nt t be cnstrued as an fficial Department f the Army psitin unless s designated by ther authrized dcuments. Citatin f manufacturer s r trade names des nt cnstitute an fficial endrsement r apprval f the use theref. Destry this reprt when it is n lnger needed. D nt return it t the riginatr.

3 ARL-CR-0763 MAR 2015 US Army Research Labratry Advances in Nancarbn Metals: Prcess by P Chris Pistrius and Pengcheng Yan Carnegie Melln University Apprved fr public release; distributin is unlimited.

4 REPORT DOCUMENTATION PAGE Frm Apprved OMB N Public reprting burden fr this cllectin f infrmatin is estimated t average 1 hur per respnse, including the time fr reviewing instructins, searching existing data surces, gathering and maintaining the data needed, and cmpleting and reviewing the cllectin infrmatin. Send cmments regarding this burden estimate r any ther aspect f this cllectin f infrmatin, including suggestins fr reducing the burden, t Department f Defense, Washingtn Headquarters Services, Directrate fr Infrmatin Operatins and Reprts ( ), 1215 Jeffersn Davis Highway, Suite 1204, Arlingtn, VA Respndents shuld be aware that ntwithstanding any ther prvisin f law, n persn shall be subject t any penalty fr failing t cmply with a cllectin f infrmatin if it des nt display a currently valid OMB cntrl number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) March TITLE AND SUBTITLE 2. REPORT TYPE Final Advances in Nancarbn Metals: Prcess 3. DATES COVERED (Frm - T) April 2013 Octber a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) P Chris Pistrius and Pengcheng Yan 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Carnegie Melln University 5000 Frbes Avenue Wean Hall 4313 Pittsburgh, PA SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) US Army Research Labratry ATTN: RDRL-WMM-F Aberdeen Prving Grund, MD PERFORMING ORGANIZATION REPORT NUMBER 10. SPONSOR/MONITOR'S ACRONYM(S) 11. SPONSOR/MONITOR'S REPORT NUMBER(S) ARL-CR DISTRIBUTION/AVAILABILITY STATEMENT Apprved fr public release; distributin is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The additin f nanscale carbn (C) t a variety f metals was develped by Third Millennium Metals and this class f materials has been called cvetics. These materials have several unusual mechanical and physical prperties, with ptential benefits in imprved energy efficiency and material perfrmance ver a brad range f applicatins. During this prject, a labratry scale cvetic prductin system was designed and built. This system addressed the 3 distinct reactin steps: 1) C disslves in cpper (Cu), where the temperature is lcally higher, 2) supersaturated C precipitates ut n the surface f the liquid Cu as graphene sheets, where the temperature is lwer, and 3) stirring disperses the graphene sheets int the Cu. The precipitatin f C was demnstrated and shwn by scanning electrn micrscpy and Raman spectrscpy using an arc melter instead f a high temperature micrscpe. The main utcme was that the maximum feasible C cntent in cvetics is the C slubility in the metal at the temperature f the arc ht spt; this maximum is apprximately 200 parts per millin by mass. 15. SUBJECT TERMS cvetics, carbn, cpper, xidatin, mechanical prperties, lcal heating 16. SECURITY CLASSIFICATION OF: a. REPORT Unclassified b. ABSTRACT Unclassified c. THIS PAGE Unclassified 17. LIMITATION OF ABSTRACT UU ii 18. NUMBER OF PAGES 24 19a. NAME OF RESPONSIBLE PERSON Kevin J Dherty 19b. TELEPHONE NUMBER (Include area cde) Standard Frm 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18

5 Cntents Acknwledgments iv 1. Intrductin 1 2. Cnclusins 3 Appendix. Cvetics 5 Distributin List 18 iii

6 Acknwledgments This wrk was supprted by the Defense Advanced Research Prjects Agency s Tactical Technlgy Office. iv

7 1. Intrductin A new prcess technlgy prvides the ability t add greater than 6-wt% nanscale carbn (C) t a brad variety f metals. The resulting materials, develped by Third Millennium Metals, LLC, are knwn as cvetic nanmaterials. 1 These materials have several unusual prperties, ntably increased strength, increased thermal cnductivity, and increased electrical cnductivity, with ptential benefits in imprved energy efficiency and material perfrmance ver a brad range f applicatins and industries including defense. This examinatin f cvetics is part f a Defense Advanced Research Prjects Agency funded prgram invlving the University f Maryland (UMD), Carnegie Melln University (CMU), and the Naval Surface Warfare Center, Carderck Divisin. The prpsed prject at CMU specifically deals with cpper (Cu)-based cvetics (see Appendix). The prcedure used t prduce the material has been described in the patent frm Third Millennium Metals. The essential elements f the prcess are: 1) a C surce is brught int cntact with mlten Cu, 2) current is applied t the Cu by means f C electrdes, and 3) mechanical stirring is applied simultaneusly. Thrugh this cmbinatin f steps, what appears t be nansized C is prduced and dispersed int the mlten Cu. The verall prcess is endthermic, where a drp in the temperature f the melt is witnessed when current is applied. The prblem addressed in this research is that the fundamental steps that lead t the frmatin f cvetics are nt knwn; the patent 1 cntains the fllwing: While the exact chemical structure f the disclsed metal-carbn material is currently nt knwn, withut being limited t any particular thery, it is currently believed that the steps f mixing and applying electrical energy result in the frmatin f chemical bnds between the metal and carbn atms, thereby rendering the disclsed metal-carbn cmpsitins unique vis-a-vis knwn metal-carbn cmpsites and slutins f metal and carbn. Furthermre, withut being limited t any particular thery, it is believed that the disclsed metal-carbn material is a nancmpsite material and the amunt f electrical energy (e.g., the current) applied t frm the disclsed metal-carbn cmpsitin initiates an endthermic chemical reactin. This creates a difficult prblem. While the practical steps required t prduce cvetics have been described by the inventrs, there is n infrmatin n the fundamental mechanism f cvetic frmatin. In further refining the prcess, the 1

8 current apprach by the develper f the technlgy (Third Millennium Metals) is t rely n empirical knwledge. An bvius limitatin t this empirical apprach is that there is little r n quantitative basis fr scaling-up r ptimizing the prcess. The current prject prpses that the prcess can be separated int 3 distinct reactin steps. If this is indeed the case, each f these steps can be executed in a separate reactr. Such separatin f prcess steps wuld allw tighter cntrl f prcess cnditins and allw the prcess t be cnverted readily t cntinuus prductin (rather than the current batch prcess). The essential technical idea is captured in the fllwing hyptheses: Cvetic cnsists f graphene sheets distributed within the metal (Cu). The applied current causes lcal heating where the electrdes enter the Cu melt. C disslves in Cu where the temperature is lcally higher (Step 1). Where the temperature is lwer, supersaturated C precipitates ut n the surface f the liquid Cu as graphene sheets (Step 2). The rle f stirring is t disperse the graphene sheets int the Cu (Step 3). The bserved endthermicity results frm the small exthermic bnding energy between liquid Cu and graphene, which is much smaller than the energy invlved in breaking Cu-Cu bnds when dispersing graphene in the Cu. Previus cmbustin analysis failed t detect C in Cu cvetic material because the xidatin rate f the cvetic material is significantly lwer than that f pure Cu. The prpsed scpe and deliverables f the prgram are described in the fllwing 6 prcedural tasks: 1) Design and build a labratry scale system fr Cu cvetic prductin. Als, prduce additinal samples f cvetic Cu, t be analyzed by the team at the UMD. 2) Theretical evaluatin f the energy balance f the prcess. 3) Experimental measurement f the xidatin rate f mlten Cu and mlten cvetic Cu in pure xygen (O). 2

9 4) Experimental test, using a high temperature micrscpe (laser scanning cnfcal micrscpy), f the prpsal that C disslves frm the C surce at higher temperature and precipitates as graphene upn cling. 5) Experimental test, using the labratry scale cvetic prcess, f the extent f lcal heating caused by the applied current t determine whether the lcal heating is sufficient t sustain C disslutin (as a necessary step befre C precipitatin as graphene). 6) Preparatin f an verall summary reprt, stating the prcess implicatins f the fundamental infrmatin btained in this prject. 2. Cnclusins This prject was successful in cmpleting all f the tasks cntained within the prpsal scpe. While nt all f the research rganizatins came t the exact cnclusins, a significant amunt f data was created that can be interpreted fr any future cvetics research. The new labratry-scale cvetic prductin facility at CMU culd be an instrumental part f a ptential larger prgram. The fllwing utcmes were achieved fr the prpsed prgram tasks: 1) Cmpleted the design and build f a labratry scale system fr cvetic prductin. Cu and silver (Ag) cvetic samples were prduced fr UMD analysis. 2) Cmpleted the theretical evaluatin f the energy balance f the prcess. This assessed the creatin f Cu-C interfaces as a pssible cause f the endthermic effect reprted by Third Millennium. Hwever, given the small cncentratin f C actually prduced, this effect is negligible. 3) The experimental measurement f the xidatin rate f mlten Cu and mlten cvetic Cu in pure O was cmpleted. N difference in xidatin behavir was seen. Testing f C cncentratin in Cu and Ag was develped via full xidatin in O (with infrared analysis f ff gas). Material prduced by Third Millennium was tested and fund t cntain less than 50 parts per millin (by mass) f C in all cases. 4) Demnstrated precipitatin f C shwn by scanning electrn micrscpy and Raman spectrscpy using an arc melter instead f a high temperature micrscpe. 5) Cmpleted the measurement f the lcal heating caused by the applied current using the labratry scale cvetic prcess. Using an infrared 3

10 camera, the lcal ht spt temperature (beneath the arc) was measured as apprximately 2,000 C. 6) In additin t this reprt, a draft paper n the prject results has been written and will be submitted fr jurnal publicatin. A cpy f that submissin will be supplied as sn as it is sent t the jurnal. The prcessing knwledge cllected during this wrk is summarized in a kinetic mdel. The main utcme is that that the maximum feasible C cntent in cvetics is the C slubility in the metal at the temperature f the arc ht spt; this maximum is apprximately 200 parts per millin by mass. 4

11 Appendix. Cvetics This appendix appears in its riginal frm, withut editrial change. 5

12 Advances in nancarbn metals: prcess Final reprt, Nv 21, 2014 Pengcheng Yan and Chris Pistrius Department f Materials Science and Engineering Carnegie Melln University Cntent Fcus f prject: prduce cvetics Cvetics Challenges Prcess mechanism Experimental & results Small scale arc melting Cvetics prductin Kinetics mdel Summary CMU CISR 2 6

13 Cvetics Metal nancarbn cmpsite Au, Ag, Cu, Zn, Al etc Single phase Upt 6 wt % carbn Imprved prperties Thermal/electrical cnductivity Strength Density CMU CISR 3 Challenge Carbn cntent 7 wt% C CMU CISR 4 7

14 Challenge Carbn cntent by EDS, XPS, SIMS (micranalysis) LECO (.5 gram, fast cmbustin), full slw xidatin 1. Pre-heating: Al 2 O 3 crucible in O 2 at 1200 C fr 2 hur 2. Calibratin pure Cu xidised fr 30 mins (backgrund) knwn graphite in Cu tube ( =~0.5%) 3. Measurement: xidatin at 1200 C fr 30 mins CMU CISR 5 Full xidatin Cu 2 O 15 min xidatin CuO 30 min xidatin Cu 2 O CuO Cu 2 O Cu Cu 2 O CuO Hetergeneus xidatin Cu drplets at bttm Cu 2 O in bttm regin Imprved xidatin N Cu drplets Cu 2 O rich in bttm regin CuO appears in tp regin CMU CISR 6 8

15 Prcess mechanism 1. Carbn surce disslves in liquid cpper at ht spt beneath arc. 2. Cpper flws away frm arc; disslved carbn precipitates as nan-carbn at the free surface f the melt. 3. Mechanical stirring distributes nan-carbn thrugh the melt. CMU CISR 7 Small scale arc melting cm Arc-melt Cu/Ag under purified argn in high-purity graphite crucibles, fr different times t test steps and CMU CISR 8 9

16 Small scale arc melting Carbn n Cu surface 1 min 3 min CMU CISR 9 Small scale arc melting Carbn n & in Cu C Al 2 O 3 Al 2 O 3 C film n Cu surface Thickness increases with arcing duratin sp 2 carbn Brad peak in bulk: amrphus carbn Steps and cnfirmed fr Cu CMU CISR 10 10

17 Small scale arc melting Carbn n Ag 1 min 3 min 7 min Carbn amunt/thickness - increase CMU CISR 11 Small scale arc melting Carbn n & in Ag C film/particles n Ag surface Thickness increases with arcing duratin sp 2 carbn N r limited carbn in bulk Steps and cnfirmed fr Ag CMU CISR 12 11

18 Arcing test Temp.&stirring speed test Cvetics prductin Set-up One electrde in melt; anther ne just abve carbn surce Temperature: thermcuple-befre arcing; thermal camera-during arcing CMU CISR 13 Cvetics prductin Stirring rd Melting Slid Cu e=0.2 Mlten Cu e=0.06 Stirring e=0.2 Temp. vibratin ~150 rpm ~23 r= 1.8 cm ~35 r= 2.7 cm Arcing e=0.2 Large Temp. increase Stirring Arc e: emissivity; bservatin windw becmes dirty, leading t lw e * If need the riginal vides, please cntact CMU CMU CISR 14 12

19 Cvetics prductin Measured Carbn Sample Remarks Stirring / min Arcing / s Graphite / wt% Activated Carbn wt% IR LECO Cu Ag CMU CISR 15 Ag cvetic Nan particle r pres Carbn peak D and G peaks, sp 2 carbn Steps cnfirmed fr Ag CMU CISR 16 13

20 Cu cvetic Shrt arcing samples N Carbn in cvetic samples (shrt time arcing) CMU CISR 17 Cu cvetic lng arcing samples Nan pres n plished samples Small carbn peak with EDS Brad peak, amrphus carbn? Steps cnfirmed fr Cu CMU CISR 18 14

21 Cmpsitin ( Atmic %) Carbn cntent With XPS Cu Cvetic CMU N. 2, plished 85 Atmic % C Atmic% O 55 Atmic % Cu Sputtering Time (Minutes) C at % O at % Cu at % 1.0± ± ±1.0 Carbn n surface nt in bulk CMU CISR 19 Carbn cntent With SIMS Higher carbn in cvetics than raw materials Need bulk analysis CMU CISR 20 15

22 Carbn cntent With full xidatin Increases with arcing, reaching 150 ppm in mass Limiting step? CMU CISR 21 Kinetics mdel Assumptin Limited by carbn diss0lutin in ht spt Ht spt size Stirring speed/flw rate Temperature (I) (II) Cnstant vlume, density (ρ C, Cu ) and initial C particles diameter (d ) Nan-carbn hmgeneusly dispersed in Cu bulk Cnditins Precipitated nan-carbn particles redisslutin C t 0 = α C t 0, α =0-1 CMU CISR 22 16

23 Kinetics mdel Parameters: k=7e-4 m/s Re=32632 Sc=0.22 D C =5.2e-7 (D 2000 C) k=~2-3e-4 m/s in liquid 1550 C C s = C A h = 1e-4 m 2 h=2e-4m V h =2e-8 m 3 d =1e-3m t=0.1s CMU CISR 23 17

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