업 종 련되는 원료, 제품( 간제품포함)

자원농업 토양, 종자, 사료, 곡물

업 원 , 분탄

가 공

산업

식품 소맥분 등, 화학조미료, 분유, 가루 차, 설탕, 소 , 인스턴트 커피

섬유 색소제, 염료, 안료

종이, 펄 목재칩, 펄 , 톱밥, 도장재, 충 제, sizing제

고무, 고분자 충 제, 안료, 고분자 pellet, 고분자가루

안료, 충 제 안료, 카본블랙, colloidal silica, 인쇄잉크

화학공업 농약, 비료, 매, 각종 화학약품

요업토, 흑연, 속산화물, 규사, 석회석, 알루미나, glass beads, 시멘트,

연삭재

철강 분 , 궤 , 분진, 석 pellet

비철 속 분진, 알루미나, 소 분(燒鉱紛), 속분

집

산업

속, 기계 속분, 분진, 연마재, 연삭재

기기기 형 재료, 텅스텐, 몰리 덴분, 실리카, 알루미나

자재료 산화티탄, 산화철, 알루미나 등, 티탄산바륨, 페라이트, 도성재료

의약, 화장품 분, 활성알루미나, 젖당, 주약(主藥), 안료, 정제, 과립, 치약

잡화 고분자 pellet, 약품

환 경

․

재해

환경기술 슬러지, fly ash, 규석가루, 분진, 매연, fume, 생활먼지

자연재해 꽃가루, 황사, , 화산재

Chapter 0. Introduction to Powder Technology

0.1 What is powder?

Powders : Finely-divided solid matter

Size : from nanometers(10-9m) to centimeters(10-2m)

syn) Particulate matter, particles

분체(粉體), 분말(粉末), 입자(粒子)

Examples of Powder: 여러 산업에서 매우 요

Liquid

Solid

Gas

Flow

Withstand deformation

compressibility

Powder

화학공업의 만 보더라도

DuPont 1985, 1992 found among 3000 products

62% : Powders, crystalline solids, granules, flakes,

dispersions, slurries and pastes

18% : powder = key intermediate products

Characteristics of Powders

They differ from molecules, atoms and solids in:

- They are finely divided, isolated solids

- They have probabilistic, statistical properties

- Their surface properties are important in their behavior.

They differ from solids, liquids, and gases in:

- As with solids, bulk powders can withstand deformation.

- As with liquids, they can flow.

- As with gases, they exhibit compressibility.

0.2 What Is Powder Technology?

Based on Fundamentals such as:

- Characteristics of Single Particle

(Size, shape, composition, crystallinity, optical,

electrostatic, surface)

- Particle-Fluid Interaction

(Drag, settling, electrical field effect, diffusion,

phoresis,inertial motion,permeation)

- Particle-Particle Interaction and Particle Assembly Mechanics

(Adhesion, dispersion, bulk solid mechanics)

Applications

- Fluidization, Storage-Feeding and Transport

- Separation/Classification

(Sedimentation, cyclone, impactor, ESP, scrubber, filtration)

- Change in Powder State

(Mixing(segregation), packing, granulization, sintering,

powder explosion, health effect)

- Production(Crushing/Growth)

0.3 History of Powder Technology

수천년 통의 분체기술

- Egypt:

․Silts deposited: agriculture, raw materials for brick and

ceramic handicrafts

․Winnowing and crushing of grains, followed by kneading of

flour

․Physical liberation of precious metals and gems by crushing

․Colloidal rheology : mixing of black soot with water,

vegetable gum for ink, production of bricks from mud, sand and

straw

- Leading industries for many generations :

․Production of pottery

․Milling of flour for bread

․Mining, mineral processing, metallurgy

․Soils in civil engineering

Changes in composition and the state of aggregation(phase)

Transport phenomena

Chemical process technology

Thermal process technology

Mechanical process technology

Chemical reactions

Phase changes

Transfer between phases

(separation processes)

Alteration to the state of mixing and dispersity

Heat and mass transfer

Convective transport of continua

Transport of particles

Thermal

Mechanical

Changes of state and transport phenomena in process engineering

H.Rumpf, “Particle Technology”, Chapman and Hall(1960)

산업 명과 분체공학

- Powder industries in early U.S.(18C - 19C)

․Potash, indigo dye, salt, saltpeter, gunpowder, lamp black and

white lead

화학공학의 태동과 분체공학

- Important role in birth of chemical engineering(early 20C)

․Strong ties between chemical engineering and powder handing

industries

․Introduction of the concept of unit operation in chemical

engineering

☞ Early Texts in Unit Operations

Walker(1923), Badger and McCabe(1931) :

devoted 40 % to particle processing

- Hans Rumpf(1960's) classified process technology(chemical

engineering) as follows:

Powder in mass production(since ‘60s)

Particles as a Source ofAir Pollution(since ‘70s)

Particles as AdvancedMaterials(since ‘80s)

Processesinterested

Comminution(Breakown)Size enlargementTransportationStorageCollection(Recovery)

Collection(Removal)FormationTransport

Growth(Buildup)DispersionSinteringCharacterizationApplications

Powdersinterested

Cement/Fertilizer/Sugar/Mining products/Pharmaceuticals/Pigments

Particles related withPublic health,Meteorology and AerosolresearchIndoor air qualityClean room technology

New materials with new-born properties

Sizeinterested

≥10 μm Down to submicron sizes Nano-sized particles

분체공업의 변화추이

무시당한 분체공학

- Following World War II, petrochemical industries: main stream of

chemical engineering

☞ gas-liquid, and liquid-liquid systems

․U.S.: neglect on powder technology

☞ lag behind Japan, Germany and U.K.

․Treated as "low-tech"

: Mathematical interpretation : not completely available

☞ Scale-up depends on empiricism

: Messy to handle and store

분체기술의 미래

- Powder technology as "New"-Tech vital to:

․Advanced materials: Nanoparticles

: information, communication, aircraft, space science,

biology, military use

․Environmental application

: particulate pollution control, climate control, nuclear

- 6 -

control

그러나 분체산업의 황은!

- Two-year study by the Rand Corporation(1986)

․ Recently built plants perform no better than those built in the

1960's.

․ Operate at only 50% of design capacity(1/5 : less than 20%)

cf. average: 90-95% of design capacity

․ Start-up time : 6 times as long as liquid/gas processing plants

(though 3.5 times expected)

Solutions

- Needs on basic research on solids behavior

․Background theory

․Equipment performance

- Needs the development of scale-up strategy

- Needs information feedback from plant engineers to designers and

R & D departments.

0.4 Prospects of Nanoparticles

1) Definition by size

- Particles having sizes less than 0.1m (100nm)

1st generation nanoparticles: <100nm

2nd generation nanoparticles: <10nm

- Lower limit of nanoparticles: ~1nm

*Other names of nanoparticles

- ultrafine particles, clusters, nanocrystals, quantum dots

cf. colloids, aerosols, hydrosols, organosols

2) Properties of Nanoparticles

- 7 -

E E EεF

εF/N

Bulk Pt Pt UFP Pt 원자

d>>l d~l d<<l

Bulk의 미소화 + α

i) Volume Effect

- Kubo 효과 (양자크기효과)

원자가 자의 에 지

Bulk :연속 (band) → 이산

e.g.비열, 자화율 변화, 흡수 증 , 선택흡수

- 강자성(Ferromagnetic) 입자의 단자구화

Bulk :다자구(multidomain) → 단자구(single domain)

→ 상자성(≈10nm, superparamagnetic)

e.g.자기기록재료

- 기체 내 운동 : 비연속 효과 (Noncontinuum effect)

입자크기 d ～ mean free path l

- 학 특성

입자크기 d ～ 빛의 장 λ

산란(scattering): 기하학 or Mie → Rayleigh 산란

(transparent)

ii) Surface Effect

- 표면 증가

한변의 크기 ( 원자 수)

전체 원자의 수 전체 표면원자의비율(%)

모서리에 있는입자의 비율(%)

102050

100

10008000

1250001000000

48.827.011.55.9

10.42.8

0. 460.12

입방체 입자의 크기와 표면원자의 비율

모서리길

이 (nm) 한입자의 원자수

전체 표면적 (cm2)

표면에너

지 (erg)

표면에너

지/결합에너지의 비

5 10 100 1000 10000 100000

1.06×104

8.46×104

8.46×107

8.46×1010 8.46×1013 8.46×1016

8.54×107

4.27×107

4.27×106

4.27×105 4.27×104 4.27×103

1.88×1011

9.40×1010

9.40×109

9.40×108

9.40×107

9.40×106

5.51 2.75 0. 275 0.0275 0.00275 0.000275

구리미립자의 입경과 표면에 지

Size effect of gold(Au) fine particles on their

melting point

- 8 -

- 표면에 지 증가 :

* 융 강하, 용해도증가, 비 강하 (증기압 증가)

소성온도 하, 매활성증가

결정구조의 이상(abnormality)

초미립자 및 입경 Bulk 금속 융점 소결온도

Au(3nm):900K In(4nm):370K Ni(20nm):~200oC W(22nm):~1100oC

1300K 430K >700oC >2000oC

속 미립자의 융 소결온도

ReactantsA+B Coagulation

CondensationNucleation

Reaction Vapor(monomer) Nuclei

Bulk materials Evaporation

- 9 -

3) Formation of Nanoparticles: Build-up Processes

1) Nucleation

- Formation of nuclei(핵): new-born particles

- Requires supersaturation

S=PP 0

↑in gas

S=CC 0

↑in liquid

where P0, C0: vapor pressure. saturation concentration

* Physical methods

- Heating for evaporation or sublimation of bulk source...

by electrical heating, laser, plasma etc.

- Cooling for thermodynamic saturation concentration...

by adiabatic expansion

* Chemical method

분자

입자

분자

입자

분자의 입자표면

충돌

- 10 -

The molecules often form via chemical reaction...

Heating for supplying heat of reaction

by electrical heating, laser, plasma etc.

- Homogeneous vs. Heterogeneous Nucleation

불균일 핵생성이 균일 핵생성보다 일어나기 쉽다.

2) Growth of particles (nuclei)

i) Condensation(응축):

The newly formed nuclei can grow in size as a result of monomers

hitting the particles and sticking, causing the particles to increase

in size.

핵 는 입자의 표면에 증기, 즉 monomer의 분자가 확산되어와

응축하여 성장..

ii) Coagulation (응집)

The particle can also increase is size as a result of collision

and subsequent coagulation with other particles.

입자와 입자가 충돌하여 결합하여 하나의 입자로 성장한다.

* 입자의 체 성장과정

모노머농도

시 간

유도기간

핵생성, 응축

응축, 응집

숙성 ⇒포화농도

임계농도

- 11 -

Physical preparation1)

Bulk

monomers nuclei particles

Chemical preparation2)

Bulk precursor molecules

4) Applications of Nanoparticles

i) Major properties of nanoparticles for applications

Particles shape: size and its distribution, shape, specific surface

area

Composition: stoichiometry, impurities, composite components

Crystallinity: amorphous, single or poly-crystalline, lattice defect

Agglomeration: agglomerate structure, agglomerate size

ii) Classification of Applications

with respect to state for use

- 12 -

10 15 20 years

분체

광촉매/자성유체

자기기록매체

박막/표면개질

복합재료

센서/필터

압전체

전극재료

광/전자기 device

자기기록매체

공구/구조용 재료

수송/에너지/화학산업

에너지/항공/우주산업

- Dispersed state

안료, 고무나 라스틱의 filler, 자기기록재료, 자성유체, 연마제,

고체윤활제, 매, 형 체, 연료, 식품, 농약, 화장품

- Sintered state: High density

구조재료, 인공 , 인공치아, 내열재료, 기 , 후막 박막재료

- Porous structure

매, 가스센서, 세라믹필터, 극재료

iii) Future of nanoparticles