Unit.5.Nonmetallic Matls. Cbn.nd Diamond. Notes
Transcript of Unit.5.Nonmetallic Matls. Cbn.nd Diamond. Notes
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NON METALLIC
MATERIALS
(i) Cubic Boron
Nitride(CBN(ii) DIAMONDS
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Cubic Boron Nitride(CBN
Cubic Boron Nitride(CBN)
Superabrasives
Cubic Boron Nitride(cBN) is second in
hardness on! todia"ond
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Cubic Boron Nitride
Cubic boron nitride (CBN) is as!nthetic che"ica co"pound "adeup o$ boron and nitro%en ato"s in a
one&to&one ratio' nie other t!pes o$ boron nitride* it
e+ists as acubic cr!sta attice* ,ithits ato"s arran%ed in a s!""etrica*cube&shaped structure ie thecr!staine structure o$ dia"ond'
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Cubic Boron Nitride
Its "ateria properties incudee+tre"e hardness* stabiit! underheat* and superior che"ica
resistance' Cubic boron nitride is the second&
hardest no,n "ateria a$terdia"ond* "ain% it use$u in a ,idevariet! o$ industria appications*,here it is o$ten used as an abrasiveor cuttin% too'
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Cubic Boron Nitride
A boron nitride co"pounds areproduced s!nthetica!* since the!are not $ound in nature'
The process starts ,ith boric acid* a
co"pound o$ boron* o+!%en* andh!dro%en* or ,ith borontrio+ide*,hich is "ade up o$ boron and
o+!%en' Either o$ these co"poundscan be reacted ,ith urea ora""onia* ,hich contain nitro%en* toproduce a po,der o$ boron nitride'
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Cubic Boron Nitride
The po,der is cr!stai-ed throu%hintense heat to $or"he+a%ona boron nitride* ,hich
has a he+a%ona cr!sta structureanao%ous to that o$ %raphite*aprecursor o$ s!nthetic dia"ond'
.e+a%ona boron nitride is thenheat&treated under hi%h pressureto $or" cubic boron nitride
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Cubic Boron Nitride
CBN has severa advanta%es as an industria"ateria'
It is a"ost as hard as dia"ond* "ain% ituse$u $or cuttin% and abrasion o$ "etas andother substances' The heat resistance o$ CBN is
aso /uite hi%h' Dia"ond be%ins to deco"pose to
carbon dio+idein air at around 0112C*,hereas cubic boron nitride is stabe in air up
to about 3*4112C' In industria %rindin% appications and other
processes ,here intense heatis %enerated*CBN is pre$erred over dia"ond'
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Cubic Boron Nitride
Another advanta%e o$ CBN as anaternative to dia"ond is its che"icastabiit! in the presence o$ nice* iron*and reated substances'
Dia"ond is soube in these "etas*"eanin% that it reacts ,ith the"che"ica! and dissoves'
This "aes it useess as a too $or cuttin%
iron or stee' CBN* on the other hand* does not react
and can there$ore be used to cut these"aterias
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Cubic Boron Nitride
The variet! o$ CBN used in industriacuttin% toosis no,n aspo!cr!staine cubic boronnitride (5CBN)'
5CBN is "anu$actured b!sinterin% cubic boron nitride partices,ith cera"ics'
In sinterin%* the boron nitride is paced ina $urnace under hi%h heat and pressure
that binds it ,ith the cera"ic* $usin% intothe e+tre"e! hard substance used $or%rindin% and cuttin%'
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DIAMONDS
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DIAMONDS
Dia"ond is the aotrope o$ carbonin,hich the carbonato"s are arran%edin the speci6c t!pe o$ cubic attice
caed dia"ond cubic' Dia"ondis an optica! isotropic
cr!stathat is transparent to opa/ue'
O,in% to its stron% covaent bondin%*
dia"ond is the hardestnatura!occurrin% "ateria no,n'
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DIAMONDS
Due to i"portant structura,eanesses* dia"ond7stou%hnessis on! $air to %ood'
The precise tensie stren%tho$dia"ond is unno,n* ho,everstren%th up to 81 95ahas been
observed* and it coud be ashi%h as :1;
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DIAMONDS
The anisotrop!o$ dia"ond hardness iscare$u! considered durin%dia"ond cuttin%' Dia"ond has ahi%h re$ractive
inde+ (
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DIAMONDS
Trace i"puritiessubstitutiona! repacin%
carbon ato"s in adia"ond7s cr!sta attice* andin so"e cases structura
de$ects* are responsibe $orthe ,ide ran%e o$ coors seenin dia"ond'
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DIAMONDS
Most dia"onds are eectricainsuators but e+tre"e!
e@cient ther"a conductors'nie "an! other "ineras*the speci6c %ravit! o$
dia"ond cr!stas ('=
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DIAMONDS
A tra! o$ dia"ond heatspreaders'
The! are used ineectronic devices andother paces ,here a oto$ heat is %enerated in as"a area'
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DIAMONDS
Dia"onds can survive conditionsthat ,oud destro! other "ateriasand so the! have "an! uses in
science and industr!' Natura dia"onds are rare andver! e+pensive so it hasn7t been
possibe to "ae $u use o$ theira"a-in% natura properties untirecent!'
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DIAMONDS
No, ,e have the abiit!to %ro, s!nthetic
dia"ond cr!stas and,a$ers* openin% up
,hoe ne, ,ords o$technoo%!'
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DIAMONDS
Dia"onds have a ran%e o$ uni/ue properties Dia"ond is the hardest no,n natura
"ateria on Earth'
Dia"ond conducts heat = ti"es $aster than
copper*,hich is ,h! it $ees cod to thetouch'
5ure dia"ond is the "ost transparent"ateria no,n'
It reects visibe i%ht* utra&vioet i%ht* andin$rared i%ht* and a the $re/uenciesinbet,een'
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DIAMONDS
Dia"ond can be an insuator or aconductor* so it can either ao,eectricit! to pass throu%h or
boc it'
Dia"ond can survive intact inenviron"ents that ,i destro!
other "aterias' It can survivesevere ph!sica* che"ica andradioactive $orces'
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DIAMONDS
I$ !ou pace dia"ondsinside the hu"anbod! the! ,i nottri%%er an i""une
response
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DIAMONDS
No, ,e can "aearti6cia dia"onds* ,e
can "ae better use o$these properties inscience and en%ineerin%'.ere are so"e e+a"pes'
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DIAMONDS
Sur%er! Dia"ond bades on scapes have
an utra&6ne ed%e that can cut ver!precise!* ,hich is i"portant $orsur%er!'
Dia"ond aso re"ains sharp $or"uch on%er than stee' As it cuts*
it can trans"it aser i%ht* ,hichao,s it to cauterise the ,ound tocontro beedin%'
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DIAMONDS
Teeco""unications Dia"ond cubes can ao, severa
si%nas at once to pass aon% a
cabe* a at dierent ,aveen%thso$ i%ht' This "aes the" use$uin teeco""unications'
The! can aso ,ithstand hi%h&ener%! conditions and chan%es inte"perature'
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DIAMONDS
.eat spreaders
.eat passes throu%h dia"onds $ar"ore /uic! than it passes
throu%h copper'
This "aes it use$u as a heatspread in paces ,here ots o$ heat
is %enerated in a s"a space' Microeectronic devices are one
e+a"pe'
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DIAMONDS
indo,s
Dia"ond ,indo,s provide protection$ro" e+tre"e conditions in so"e
scienti6c e+peri"ents that usesubstances ie acidic i/uids or"oten pastics'
Dia"onds ,indo,s are aso ver!
transparent and so the! ao, in$ra&red "easurin% devices to "onitor thesubstances sa$e! $ro" behind the,indo,'
DIAMONDS
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DIAMONDS
A diamond window
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DIAMONDS
.eath care
Dia"ond is "ade o$ carbon and
so it is the idea "ateria to usein our carbon&based bodies'
It ,i not ,ear a,a! or tri%%er
an i""une response'
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DIAMONDS
Scientists are deveopin%dia"ond i"pants that coudhep "onitor heath or tae
over the roe o$ $aiin% tissues' The! are aso drea"in% o$ tin!dia"ond "achines that one
da! "i%ht speed round thebod! "ain% repairs'