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Solutions for Fundamentals of Modern Manufacturing , 5e (published by Wiley)  MPGroover 2012

16 PROCESSING OF CERAMICS AND CERMETS Review Questions 16.1

Wht is is the differ differen!e en!e bet"een bet"een the the trdition trditionl l !er#i!s !er#i!s nd nd the ne" ne" !er#i!s, !er#i!s, s fr s r" #terils #terils re !on!erned$ Answer. %he trditionl !er#i!s re bsed on hydrous lu#inu# sili!tes (!ly), "heres the ne"

!er#i!s re bsed on si#pler !o#pounds su!h s o&ides, nitrides, nd !rbides. 16.2 16.2

'ist 'ist the bsi! bsi! steps steps in the the trditi trdition onll !er#i!s !er#i!s pro!e pro!essi ssin n seuen seuen!e. !e. Answer. %he seuen!e is (1) preprtion of r" #terils, (2) shpin, (*) dryin, nd (+) firin.

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Wht is is the te!hni! te!hni!l l differen!e differen!e bet"een bet"een !rushin !rushin nd nd rindin rindin in in the preprtion preprtion of of trditionl trditionl !er#i! r" #terils$ Answer. rushin is perfor#ed to redu!e lre lu#ps of #inerl to s#ller si-e. Grindin is 

se!ondry pro!ess "hi!h further redu!es the prti!le si-e to fine po"der. 16.+ 16.+

es!rib es!ribee the slip !sti !stin n pro!es pro!esss in trditio trditionl nl !er#i !er#i!s !s pro!ess pro!essin in.. Answer. /n slip !stin,  slurry of !ly is poured into  plster of Pris #old, "hereupon "ter is

bsorbed fro# the slurry into the plster to for#  !ly lyer inst the #old "ll. %he re#inin slurry is usully poured out to leve  hollo" prt. 16.5

'ist nd nd briefly briefly des!ribe des!ribe so#e of the plsti! plsti! for#in for#in #ethods #ethods used to shpe shpe trditionl trditionl !er#i!  produ!ts.  produ!ts. Answer. %he plsti! for#in #ethods in!lude (1) hnd #odelin, #oldin, nd thro"in (2)

 ierin,  ierin, "hi!h "hi!h is is  #e!hni-ed #e!hni-ed e&tension e&tension of of hnd thro"in thro"in  used to #nuf!tur #nuf!turee bo"ls nd pltes pltes (*) plsti! pressin, in "hi!h  !ly slu is pressed in  #old nd (+) e&trusion, in "hi!h the !ly is !o#pressed throuh  die openin to #e lon pie!es of unifor# !ross se!tion. 16.6 16.6

Wht Wht is the the pro pro!es !esss of of i ie eri rin n$$ Answer. 3ierin is  !ly for#in pro!ess tht uses  !onve& #old on  potters "heel. %he !ly is

first pressed into rouh shpe nd then rotted nd for#ed "ith  ier tool to finl shpe. /t is suited to the #nuf!ture of flt"re (e.., dinner pltes). 16.4

Wht is is the differ differen!e en!e bet"een bet"een dry dry pressin pressin nd se#idry se#idry pressin pressin of trdition trditionl l !er#i! !er#i! prts$ prts$ Answer. %he differen!e is in the strtin !ly. or se#idry pressin, the !ly hs  typi!l "ter !ontent of 107 to 157. or dry pressin, the "ter !ontent is usully usully less thn 57. 57. ry !ly hs virtully no plsti!ity, nd so this i#poses !ertin li#ittions on prt eo#etry in dry pressin.

16.8 16.8

Wht Wht hppe hppens ns to to  !er#i !er#i!! #teri #teril l "hen "hen it it is sint sintered ered$$ Answer. Sinterin of reen !er#i!s (or po"dered #etls) !uses bondin bet"een the !er#i!

rins, "hi!h is !!o#pnied by densifi!tion nd redu!tion of porosity. 16.9 16.9

Wht Wht is the the n#e n#e iven iven to to the furn furn!e !e used used to to fire fire !er#i! !er#i! "re$ "re$ Answer. :iln.

16.10 Wht is l-in l-in in trditio trditionl nl !er#i!s !er#i!s pro!essin$ pro!essin$ Answer. Gl-in refers to the pro!ess of puttin  !er#i! !otin on the surf!e of the !er#i!

 pie!e. %he !otin, !otin, usully usully !onsistin !onsistin of !er#i! !er#i! o&ides, o&ides, is is referred referred to s s  l-e. l-e. ;&!erpts fro# this "or #y be reprodu!ed by instru!tors for distribution on  notforprofit bsis for testin or instru!tionl purposes only to students enrolled in !ourses for "hi!h the te&tboo hs been dopted.  Any other reproduction reproduction or translation of this work work beyond that permitted by Sections 107 or 108 of the 1976 United States Copyriht Act without the permission of the copyriht owner is unlawful!

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Solutions for Fundamentals of Modern Manufacturing , 5e (published by Wiley)  MPGroover 2012

16.11 16.11 Why is the dryin dryin step, so i#portnt i#portnt in the pro!essin pro!essin  of trditionl trditionl !er#i!s, !er#i!s, usully usully not reuired reuired in  pro!essin  pro!essin of ne" !er#i!s$ !er#i!s$ Answer.
ryin is only needed "hen the reen pie!e !ontins "ter. 16.12 Why is r" #teril #teril preprti preprtion on #ore i#portnt i#portnt in the the pro!essin pro!essin of ne" ne" !er#i!s thn thn for trditionl !er#i!s$ Answer.
de#ndin for ne" !er#i!s. 16.1* Wht is the the free-e dryin dryin pro!ess pro!ess used to #e #e !ertin ne" ne" !er#i! po"ders po"ders$$ Answer. /n free-e dryin, slts re dissolved in "ter nd spryed into s#ll droplets tht re

i##editely fro-en the "ter is then re#oved fro# the droplets in  v!uu# !h#ber, nd the free-edried slt is de!o#posed by hetin to for# the !er#i! po"ders. 16.1+ 16.1+ es!rib es!ribee the do!tor do!torbl blde de pro!es pro!ess. s. Answer. /n the do!torblde pro!ess,  !er#i! slurry is flo"ed onto  #ovin fil# "hi!h psses

under  "iper blde, so tht the resultin !er#i! is in the for# of  thin reen sheet "hi!h is dried nd reeled onto  spool for subseuent shpin nd sinterin. 16.15 'iuid 'iuid phse sinterin sinterin is used used for Wo !o#p!ts, !o#p!ts, even thouh thouh the sinterin sinterin te#pertures te#pertures re re  belo" the #eltin #eltin points points of either either W W or o. =o" is is this possible$ possible$ Answer. %he #eltin point of !oblt is redu!ed "hen W is dissolved in it. >t the sinterin

te#pertures used for Wo, W rdully dissolves in the !oblt, redu!in its #eltin point to the sinterin te#perture. %hus does liuid phse sinterin sinterin o!!ur in the Wo syste#. 16.16 Wht re re so#e desin desin re!o##endti re!o##endtions ons for for !er#i! !er#i! prts$ prts$ Answer. %he uidelines in!lude the follo"in? (1) sube!t !er#i! prts to !o#pressive stresses, not

tensile stresses (2) !er#i!s re brittle, so void i#p!t lodin (*) prt eo#etries should be si#ple (+) use lre rdii on inside nd outside !orners (5) te into !!ount shrine nd (6) no s!re" threds.

;&!erpts fro# this "or #y be reprodu!ed by instru!tors for distribution on  notforprofit bsis for testin or instru!tionl purposes only to students enrolled in !ourses for "hi!h the te&tboo hs been dopted.  Any other reproduction reproduction or translation of this work work beyond that permitted by Sections 107 or 108 of the 1976 United States Copyriht Act without the permission of the copyriht owner is unlawful!

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