Powde r flowability Unia xia l c o mpre ssio n te st 1 c 1 : - PowerPoint PPT Presentation

Powde r flowability at low str e sse s: ball inde ntation Co lin Ha re De partme nt o f Che mic al and Pro c e ss E ng ine e ring , Unive rsity o f Surre y

Powde r flowability � Unia xia l c o mpre ssio n te st σ 1 σ c σ 1 : pr e -c o nso lidatio n str e ss = flo w func tio n, ff c σ c : unc o nfine d yie ld str e ss [1} Sc hulze , D., 2007 “Po wd e rs a nd b ulk so lid s: b e ha vio ur, c ha ra c te riza tio n, sto ra g e a nd flo w”, Spring e r 2

F lowability me asur e me nt � Mo re c o mmo nly me a sure d with she a r c e lls σ n σ 1 τ τ σ σ c σ 1 [1} Sc hulze , D., 2007 “Po wd e rs a nd b ulk so lid s: b e ha vio ur, c ha ra c te riza tio n, sto ra g e a nd flo w”, Spring e r 3

Pr opose d me thod Ba ll inde nta tio n 2 F F � = = ( ) max max H F max π − 2 A 2 Rh h � E la stic a lly de fo rming re g io n pro vide s a dditio na l c o nstra int: H = σ C . c [2] Ha ssa npo ur, A., Gha d iri, M., 2007 “Cha ra c te risa tio n o f flo w o f lo o se ly c o mpa c te d c o he sive po wd e rs b y 4 b a ll ind e nta tio n”, Partic le & Partic le Syste ms Charac te rizatio n 24, 117-123

Ball inde ntation � Ro utine ly use d fo r c ha ra c te rising ha rdne ss o f c o ntinuum so lids C is kno wn fo r me ta ls (~3) 3 � � C c a n b e c a lc ula te d fro m ma te ria l pro pe rtie s fo r o rg a nic s & po lyme rs 4 � nde nta tio n pro c e dure ha s b e e n e sta b lishe d 5 : I � I nde nte r size to b e use d fo r a g ive n pa rtic le size � Minimum a mo unt o f po wde r ne e de d � Be d d ia me te r � Be d he ig ht � T o wha t de pth the inde nt sho uld b e ma de [3] T a b o r, D., 1951 “T he ha rd ne ss o f me ta ls”, Clare ndo n Pre ss [4] Jo hnso n, K .L ., 1985 “Co nta c t me c ha nic s”, Camb ridg e Unive rsity Pre ss 5 [5] Za fa r, U., Ha re , C., Ha ssa npo ur, A., Gha d iri, M., 2017 “Ba ll ind e nta tio n o n po wd e r b e d s fo r a sse ssing flo wa b ility: Ana lysis o f o pe ra tio n wind o w”, Po wde r T e c hno lo g y 310, 300-306.

Inde nte r size Minimum: 5 4.5 dne ss (kPa) 4 3.5 3 2.5 2 1.5 Har 1 0.5 0 0 5 10 15 20 25 30 35 D i / D p [5] Za fa r, U., Ha re , C., Ha ssa npo ur, A., Gha d iri, M., 2017 “Ba ll ind e nta tio n o n po wd e r b e d s fo r a sse ssing 6 flo wa b ility: Ana lysis o f o pe ra tio n wind o w”, Po wde r T e c hno lo g y 310, 300-306.

Minimum amount of powde r Be d diame te r Be d he ight 14 7 dne ss (kPa) dne ss (kPa) 12 6 10 5 8 4 6 3 4 2 Har Har 2 1 0 0 0 25 50 75 100 125 150 175 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Be d he ight/ Par tic le diame te r D i / D d [5] Za fa r, U., Ha re , C., Ha ssa npo ur, A., Gha d iri, M., 2017 “Ba ll ind e nta tio n o n po wd e r b e d s fo r a sse ssing 7 flo wa b ility: Ana lysis o f o pe ra tio n wind o w”, Po wde r T e c hno lo g y 310, 300-306.

Inde ntation de pth 35 dne ss (kPa) 30 25 20 15 Har 10 5 0 0 0.2 0.4 0.6 0.8 1 h / R i [5] Za fa r, U., Ha re , C., Ha ssa npo ur, A., Gha d iri, M., 2017 “Ba ll ind e nta tio n o n po wd e r b e d s fo r a sse ssing 8 flo wa b ility: Ana lysis o f o pe ra tio n wind o w”, Po wde r T e c hno lo g y 310, 300-306.

Inde ntation pr oc e dur e nde nte r dia me te r ≥ 17 d p � I Be d dia me te r ≥ 1.5 D I � nd Be d he ig ht ≥ 40 d p � Size d 50 Diame te r (mm) Be d he ight Be d Volume ( μ m) (mm 3 ) (mm) Be d Inde nte r 50 0.85 1.7 2 5 100 1.7 3.4 4 40 200 3.4 6.8 8 300 500 8.5 17 20 4500 i ) ≥ 0.4 � Dime nsio nle ss pe ne tra tio n de pth ( h / R [5] Za fa r, U., Ha re , C., Ha ssa npo ur, A., Gha d iri, M., 2017 “Ba ll ind e nta tio n o n po wd e r b e d s fo r a sse ssing 9 flo wa b ility: Ana lysis o f o pe ra tio n wind o w”, Po wde r T e c hno lo g y 310, 300-306.

De te r mining c onstr aint fac tor � Ge ne ra lly we wa nt to kno w the unc o nfine d yie ld stre ss � Ne e d to kno w c o nstra int fa c to r � Ho w do e s c o nstra int fa c to r va ry with pa rtic le pro pe rtie s? � Ca n she a r c e ll da ta b e re lia b ly e xtra po la te d to lo w stre ss? Mate r ials � I nde nta tio n te ste d fo r wide ra ng e o f po wde rs � Sila nise d g la ss b e a ds (va rying size distrib utio ns) � F o o d po wde rs – swe e te ne r, ma ize sta rc h, pe a pro te in � I no rg a nic po wde rs – lime sto ne , tita nia , ta lc , c o ppe r Me thods � F T 4 she a r c e ll � Ba ll inde nta tio n 10

Unc onfine d Yie ld Str e ngth ff c =2 ff c =1 3.5 45- 53 μ m e ngth (kPa) 53- 63 μ m ff c =4 3 63- 75 μ m 75- 90 μ m 2.5 90- 106 μ m Unc onfine d yie ld str 2 1.5 ff c =10 1 0.5 0 0 2 4 6 8 10 12 Major pr inc ipal str e ss (kPa) 11

Har dne ss 7 45- 53 μ m 53- 63 μ m 6 63- 75 μ m 75- 90 μ m 5 dne ss (kPa) 90- 106 μ m 4 3 Har 2 1 0 0 2 4 6 8 10 12 Major pr inc ipal str e ss (kPa) 12

Constr aint fac tor 13

Size distr ibution e ffe c t 3.0 2.5 aint fac tor 2.0 1.5 Constr 1.0 63- 75 μ m 53- 90 μ m 0.5 45- 106 μ m 63- 75 μm + 10% <25 μm 0.0 0 2 4 6 8 10 12 Major pr inc ipal str e ss (kPa) 14

Adhe sion to the piston 15

L ow str e ss be haviour 16

Compar ison of te c hnique s 17

She ar ing at low str e sse s 18

F ood powde r s – she ar c e ll ff c =1 ff c =2 ff c =4 ff c =10 19

Constr aint fac tor 20

Slip- stic k be haviour : pe a pr ote in 21

Slip- stic k be haviour : pe a pr ote in 22

Slip- stic k: str ain r ate e ffe c t 23

Compar ison of te c hnique s - maize 1.4 3 e ngth (kPa) ma ize sta rc h ind she a r c e ll e ngth (kPa) ma ize sta rc h b a ll ind e nta tio n 1.2 2.5 1.0 2 Unc onfine d yie ld str Unc onfine d yie ld str 0.8 1.5 0.6 1 0.4 0.5 0.2 0 0.0 0 2 4 6 8 10 12 14 0 0.5 1 1.5 2 Major pr inc ipal str e ss (kPa) Major Pr inc ipal Str e ss (kPa) 24

She ar ing at low str e sse s 25

Inor ganic powde r s 35 tita nia ta lc 30 lime sto ne c o ppe r 25 dne ss (kPa) 20 15 Har 10 5 0 0 5 10 15 20 25 Major pr inc ipal str e ss (kPa) 26

Inor ganic powde r s 27

Conc lusions � F lo wa b ility c a nno t b e e a sily me a sure d a t lo w stre sse s using she a r c e lls � T a rg e t stre sse s o fte n no t o b ta ine d � De te rmine d yie ld lo c us ma y b e inc o nsiste nt � Ba ll inde nta tio n c a n pro vide re pro duc ib le me a sure me nts o f flo wa b ility a t lo w stre sse s � Re q uire s c o nstra int fa c to r to b e kno wn (o r de te rmine d) � Co nstra int fa c to r fo und to b e inde pe nde nt o f a pplie d stre ss � T ho ug h va rie s (~ 2 – 6) fo r diffe re nt ma te ria ls � Re duc e s slig htly with d 50 , tho ug h inc re a se s with fine s a dditio n � Se ve ra l po wde rs e xhib it sha rp re duc tio n in she a r stre ss a t lo we r stre sse s � Be ha vio ur a t hig he r stre sse s c a nno t b e re lia b ly e xtra po la te d 28

F utur e wor k � DE M will b e use d to a na lyse C a t lo w stre sse s � And influe nc e o f pa rtic le sha pe o n C � xpe rime nta lly a sse ss de pe nde nc y o f C o n s urfa c e e ne rg y E � A ra ng e o f c o a ting s a pplie d to d iffe re nt b a tc he s � I nve stig a te inde nta tio n a t hig h-stra in ra te s � Optimisa tio n o f she a r c e ll pro c e dure a t lo w stre sse s � Numb e r o f pre -she a r ste ps a pplie d � De fine d e nd po int – i.e a c c e pta b le de via tio n to de fine ste a dy sta te � Re q uire d a g re e me nt b e twe e n c o nse c utive pre -she a rs 29

Ac knowle dge me nts Collabor ator s � Dr Uma ir Za fa r � Dr Ma ssih Pa sha � Mr Ale x Sta vro u � Pro f. Mo jta b a Gha diri � Dr Ali Ha ssa npo ur � Mr T im F re e ma n � Dr Ma rty Murta g h 30