New materials througha varietyof sinteringmethods...framework of the SINTERCER project “Development of a sintering centre and know-how exchange for non-equilibrium sintering methods

E-MRS Fall Meeting

18th - 21th September 2017

Warsaw, Poland

New materials through a variety of sintering methods

Lucyna Jaworska

Centre of Materials Research and Sintering Technology,

The Institute of Advanced Manufacturing Technology,

Krakow, Poland

Solutions for Critical Raw Materials Under Extreme Conditions (CRM-EXTREME)

E-MRS Fall Meeting


Warsaw, Poland

PM production in Europe by value 2010 €8.5 billion

Magnets €0.9

billion; 11%

MIM €0.5

billion; 6%

PM Struktural

Parts/Bearings

€2 billion; 24%PM Semi

Products €0.7

billion; 8%Diamond Tools

€1.4 billion;

16%

Hard Metals €3

billion; 35%

Source: B. Williams: Powder Metallurgy: A global market review.

E-MRS Fall Meeting


Warsaw, Poland

Researches regard ceramic materials are mainly focused on:

� improving fracture toughness of KIc

� limiting grain size in compacts

� improving properties at high temperatures

� improving resistance to thermal shocks

One of the main goals of modern ceramic technologies is still the manufacture

of dense ceramic parts with submicrometric or nanostructured grains


E-MRS Fall Meeting


Warsaw, Poland

Starting

powders

Shaped Green

BodyPolycrystalline

product

Mixing

compacting

DebindingSintering

The most important factors which have influence on ceramics properties are:

• powders – their method of obtaining and characteristics (particle size, shape

and structure)

• compacting – compression ratio, dimensional changes

• Sintering – temperature, time and the furnace atmosphere


E-MRS Fall Meeting


Warsaw, Poland

Traditional and new techniques of the ceramicforming:

� cold pressing, uniaxial pressing

� cold isostatic pressing

� aqueous injection moulding

� direct coagulation casting

� electrophoretic forming

� gelcasting

� hydrolysis assisted solidification

� pressure filtration

� explosive compaction

� lithography

New materials through a variety of forming methods

E-MRS Fall Meeting


Warsaw, Poland

Sintering

Sintering

Free sintering Pressure sintering:� High

� Ultra High

� ExtremalAtmosphere:

� air

� vaccum

� protective gases

E-MRS Fall Meeting


Warsaw, Poland

Sintering

Furnace• batch sintering

• continuous sintering

Methods of heating the furnace in the sintering process

indirect direct

• Gas, liquid and solid fuels resistive

heating by means of heating elements:

�Metallic (kanthal, superkanthal,

molybdenum, tungsten, platinum,

iridium, rhodium, chromium itp.)

�Non-metallic (silicon carbide,

molybdenum disulphide, lithium

chromate, zirconium oxide,

carbon, graphite, etc.)

• inductive

• microwave

• DC pulses

• Laser (Selective Laser Sintering)

• Electrons (Electron Bean Sintering)

E-MRS Fall Meeting


Warsaw, Poland

Sintering process can be divided into three categories:

� Solid Phase Sintering

� with Luiquid Phase Sintering

� Gas Phase Sintering

Sintering

E-MRS Fall Meeting


Warsaw, Poland

Sintering of ceramic or metallic

powders is a phenomenon that

occurs spontaneously at elevated

temperatures (below melting

point), as a result of the system's

desire to lower its surface energy,

which decreases as the grains are

joined

The goal of the sintering process is to convert highly porous compacted powder

into high strength bodies. The process is often accompanied by shrinkage

Sintering

E-MRS Fall Meeting


Warsaw, Poland

The different physical phenomena used in sintering technologies

change thermodynamic conditions of sintering, which may affect the

crystalline form of the sintered phase and thereby change the properties

of the sintered material

Sintering

E-MRS Fall Meeting


Warsaw, Poland

The development of new sintering equipment opens new avenues for new

material solutions :

� Microwave sintering

� Spark Plasma Sintering

� High and Ulta High pressure sintering:

• HIP - Hot Isostatic Pressing

• HP- Hot Pressing

• HP-HT– High Pressure High Temperature Sintering

� Selective Laser Sintering

� Electron Bean Sintering

Sintering

E-MRS Fall Meeting


Warsaw, Poland

Conventional and Microwave Sintering

Heating patterns in: a) conventional furnaces; b) microwave furnaces

A.R. Von Hippel, Dielectric Materials and Applications, Technplogy Press M.I.T.J. Wiley&Son Inc. Chapman and Hall Ltd. 1954

E-MRS Fall Meeting


Warsaw, Poland

Microwave Sintering

Many ceramics present poor microwave absorption characteristics. There are transparent

to microwaves, such as SiO2 or Al2O3

Temperature distribution in ceramic material heated by conventional heating, microwave

heating and microwave hybrid heating (Ts – surface temp.; TI – internal temp.

Sintering of ceramics – New Emerging Techniques; Romualdo R. Menezes, Pollyane M. Souto and Ruth H.G.A.

Kiminami Microwave Fast Sintering of Ceramic Materials; Edited by Arunachalam Lakshmanan, 2012 InTech

E-MRS Fall Meeting


Warsaw, Poland

Sintering process depend on:

� Microwave absorption characteristics (dieelectric loss factor (low-loss),

electrical conductivity)

� size and shape of green bodies

� Sintered materials distribution inside the furnace

M. Krage, (1981). Microwave sintering of ferrites. American Ceramic Society Bulletin, Vol. 60, pp. (1232-1234),

0002-7812

Ceramic materials will absorb microwave energy when they can be preheated to

suitable temperature using another heat source:

� Gas or electric furnace

� External susceptor material

Microwave hybrid heating MHH could result in samples with no significant

density gradient throughout the cross-section

Sintering of ceramics – New Emerging Techniques; Romualdo R. Menezes, Pollyane M. Souto and Ruth H.G.A.

Kiminami. Microwave Fast Sintering of Ceramic Materials; Edited by Arunachalam Lakshmanan, 2012 InTech

Microwave Sintering

E-MRS Fall Meeting


Warsaw, Poland

SPS/ FAST method

FCT equipment, type HP D5 (Germany)

� sintering temperature up to 2400°C

� pulse duration 1 ms to 255 ms

� heating rate in the range from 5°C/min to 400°C/min

� pressing force from 3 kN to 50 kN

� vacuum, nitorgen, argon

For SPS apparatus the

processes are realized under

pressure up to 50 MPa (max.

500MPa for SPS Sumimoto

apparatus).

E-MRS Fall Meeting


Warsaw, Poland

SPS/ FAST method

Pulsed direct current leading to cleaning and surface

activation of powders and generation of electric

discharge at neck region. Consequently, the

temperature raises very fast and densification is

completed within few minutes.

E-MRS Fall Meeting


Warsaw, Poland

Pulse heating in the SPS method

0.005 0.010 0.015 0.005 0.010 0.015

- 5 0 - 4 0 - 3 0 - 2 0 - 1 0 0 1 0 2 0 3 0 4 0 5 0

ton=15ms toff=5ms n=1 tp=0ms



E-MRS Fall Meeting


Warsaw, Poland

Current flow during heating by SPS depending on the conductivity of the sintered materials

E-MRS Fall Meeting


Warsaw, Poland

Comparison of duration in SPS/ Microwave/ Free Sintering methods

Heating rates and sintering duration in sintering processes of Al2O3 ceramics with SPS

method, microwave and free sintering methods

Piotr Putyra, Lucyna Jaworska, Marcin Podsiadło, Jolanta Laszkiewicz- Łukasik, Ceramic materials sintered using SPS

method. Materiały Kompozytowe (Composite Materials) 2015;nr 4:42–6 (in polish)

E-MRS Fall Meeting


Warsaw, Poland

Heating in Hot Pressing and SPS methods

HP vs SPS

Scheme for a) Hot Pressing

Suárez M, Fernández A, Menéndez JL, Torrecillas R, Kessel HU, Hennicke J, et al. Chapter 13: Challengesand Opportunities for Spark Plasma Sintering: A Key Technology for a New Generation of Materials. In: Ertuğ B, editor. Sintering Applications, InTech; 2013. doi:DOI: 10.5772/5370

b) Spark Plasma Sintering

E-MRS Fall Meeting


Warsaw, Poland

Temperature in HP and SPS methods

Temperature distribution (ΔT) and time (t*) needed to compensate

the temperature between set point (TA) and measured point (TI)

HP vs SPS

Kessel HU. Sintered Materials on the Way to Production by Means of Modern SPS Technologies. Ceramic Forum

International Berichte Der Deutschen Keramischen Gesellschaft 2009;10:145–52

E-MRS Fall Meeting


Warsaw, Poland

� Piston units up to 4 GPa

� Belt type anvils 6-10 GPa

� Bridgman, Toroid and Paris-Edinburg type anvils 20 GPa

� Multianvils chamber 30-100 GPa

Types of HP-HT apparatus

E-MRS Fall Meeting


Warsaw, Poland

Mixture of powders

Bridgman type apparatus

High Pressure High Temperature sintering

Assembly for high

pressure-high

temperature sintering:

1 – pyrophyllite external

gasket;

2 – internal gasket;

3 – ceramic plate;

4 – molybdenium plate;

5 – sintered sample;

6, 7 – graphite heater;

E-MRS Fall Meeting


Warsaw, Poland

HP-HT apparatus

Bridgman type anvils

HP-HT apparatus

High Pressure – High Temperature sintering

process:

�pressure: 7.8÷8.5±0.2 GPa

�temperature: 1800÷2200±50 °C

�duration of sintering process: below 1 min

E-MRS Fall Meeting


Warsaw, Poland

Stage I - pressing

Scheme of pressure distribution in the Bridgman type apparatus

σ0, τ– stress

HP-HT apparatus

E-MRS Fall Meeting


Warsaw, Poland

Stage II - sintering The example of the sintering curve

0 10 20 30 40 50 60 70 800

1

2

3

4

5

P

T [s]

P [

kW

]

0

1

2

3

4

5

R R

HP-HT apparatus

E-MRS Fall Meeting


Warsaw, Poland

Direct SLS/SLM of submicrometer Al2O3:� 800°C

� Density up 85%

� Grain size below 5μm

Multi step processes: � using the binder material to shape

ceramic;

� this binder material removed during

furnace treatment –„debinding”

J.Deckers, S.Meyers, B.Wijremblewski, , J.Vleugels, J.P. Kruth:

Direct selective laser sintering/melting of fine grained

alumina with a novel experimental setup, Mater. Sci. Tech.:

Special issue on 3D printing, 2014

EOS-EOSINT 250Xt ; Electrokorundum F120 (95-126 μm); 25-45%x250W;

layer thickness 0.1 mm; distance between lines 0.1 mmA.Stwora, G.Skrabalak (2016, IZTW Kraków)

Overview of Additive Manufacturing processes to shape ceramics

E-MRS Fall Meeting


Warsaw, Poland

Al2O3

Structure Unit cell parameters Density

[g/cm3]

Tempera

ture of

melting

point °C

a

[nm]

b

[nm]

c

[nm]

αAl2O3

Rhombohedral 0.476 0.476 1.299 3.99 2072

γAl2O3

Cubic 0.794 0.794 0.794 3.47

δAl2O3

Tetragonal 0.796 0.796 1.170 3.20

θAl2O3

Monoclinic 1.174 0.572 1.124 3.56

χAl2O3

Hexagonal 0.563 0.563 2.260 3.35

Advanced ceramics base on Al2O3

E-MRS Fall Meeting


Warsaw, Poland

Advanced ceramics base on Al2O3

Advanced ceramics based on Al2O3 exhibit

excellent properties such as high thermal

resistance, good chemical stability and moderate

to high mechanical strength. However, thefracture toughness of the materials is low.

The brittleness and poor damage tolerance have

so far limited their application

Composites:

Al2O3 + Mo

Al2O3 + SiC whiskers

Al2O3 + TiB2

Al2O3 + …

Al2O3 + cBN

www.ceramtec.com

E-MRS Fall Meeting


Warsaw, Poland

Al2O3 through various sintering techniques

Powder ID, Manufacturer Characteristics

Al2O3-α, Alcoa

+ sintering aid: 0.3 wt.% MgO

Al2O3-α > grade CT300-SG, 0.44 µm

Preparation:

� 30 h mixing in colloidal ball mill with presence of isopropyl alcohol

� For free sintering methods, polyethylene glycol was added, to aid in green bodies

preparation

Material:

The aim of presented work was to investigate the influence of various sintering

techniques on properties an microstructure of alumina.

E-MRS Fall Meeting


Warsaw, Poland

HP-HT / HP SPS

Bridgman type apparatus

SPS Apparatus:

HP 5 FCT

Free sintering

HT16/18 Nabertherm

Furnace


Free sinteringTemperature

range:

1620°C

Duration: 60 min

SPS sinteringTemperature range:

1550°C

Duration: 1 – 15 min

Pressure: 30 – 50MPa

Atmosphere: N2, Ar,

vacuum

HP-HT/HP SPS sintering:Temperature: 2000°C

Duration: 60s

Pressure: 4 GPa

Impulse lenght: 40 ms

Impulse interval: 20 ms

Microwavesintering:Temperature:

1620°C

Duration: 60 s

Microwave furnace

E-MRS Fall Meeting


Warsaw, Poland

This work was supported by the European Commission under the FP7 Specific Programme 'Capacities' within the

framework of the SINTERCER project “Development of a sintering centre and know-how exchange for non-

equilibrium sintering methods of advanced ceramic composite materials” (REGPOT-2012-2013-1 EU FP7 Research

Potential, project no. 316232)

E-MRS Fall Meeting


Warsaw, Poland


E-MRS Fall Meeting


Warsaw, Poland


E-MRS Fall Meeting


Warsaw, Poland

1620 °C, 60 min 1620 °C, 60 s

Free sintering


Microwave sintering

E-MRS Fall Meeting


Warsaw, Poland

50 MPa, 1550 °C, 15 min 50 MPa, 1550 °C, 15 min

SPS


SPS with hBN insulation

Sintering method Mean grain size, d [µm]

Free sintering 2.57

Microwave sintering 2.86

SPS 1.41

SPS with hBN insulation 1.23

E-MRS Fall Meeting


Warsaw, Poland

Sintering

method

α-Al2O3

R-3m

θ-Al2O3

C2m

χ-Al2O3

P63/mmc

γ-Al2O3

Fd-3m

Al2O3

00-012-

0539

Initial powder ✔

Free sintering ✔ ✔

Microwave

sintering✔ ✔

✔

SPS ✔ ✔ ✔ ✔

SPS with hBN

Insulation✔ ✔

HPHT ✔ ✔ ✔ ✔

HP SPS ✔ ✔


E-MRS Fall Meeting


Warsaw, Poland


Sintering methodDensity

[g/cm3]

Young’s modulus

[GPa]Hardness HV1

KIC

[MPa*m1/2]

Free sintering 3.91 ± 0.01 383 ± 3 1868 ± 25 5.29 ± 0.31

Microwave sintering 3.87 ±0.01 387 ± 6 1600 ± 106 5.32 ± 0.42

SPS 3.95 ± 0.01 389 ± 4 1806 ± 34 6.80 ± 0.32

SPS with hBN insulation 3.95 ± 0.01 390 ± 5 1803 ± 37 7.17 ± 0.36

E-MRS Fall Meeting


Warsaw, Poland

Graphene properties

Very good conductor of heat and electricity - the measured thermal

conductivity is around 5300 W / mK (for comparison silver - 429 W / mK).

Young modulus around 1TPa

http://www.extremetech.comSource: Changgu Lee, Xiaoding Wei, Jeffrey W. Kysar, James Hone; Measurement of the

Elastic Properties and Intrinsic Strength of Monolayer Graphene ; Science 18 Jul 2008:

Vol. 321, Issue 5887, pp. 385-388.

Al2O3/graphene � anisotropy of properties

E-MRS Fall Meeting


Warsaw, Poland

Purpose:The aim of our work was to confirm indicated by SEM and TEM microstructural

analysis that the applied pressure during the sintering process (SPS) leads to the

orientation of the phase and in consequence to anisotropy of the

alumina/graphene composite

Starting powders:

Powder ID, Manufacturer Characteristics

Al2O3-α, Almatis

+ sintering aids: 0.3 wt.%MgO

Al2O3-α > 99.8%, grade A16SG, 0.3-0.6 µm

Graphene Platelets, Cheap Tubes, USA grade GPLs(4), average flake thickness <4 nm,

<4 monolayers, average particle (lateral) size 1-

2 µm


E-MRS Fall Meeting


Warsaw, Poland

SEM magnifications: 1 000x - 50 000x

GPLs(4): thickness 4 nm (a few monolayers)/ lateral size ~1-2 µm


E-MRS Fall Meeting


Warsaw, Poland

The mixtures of alumina with addition of 0.15 wt% and 2 wt.% GPLSs was

prepared using planetary mill.

• Planetary mill Pulverisette 6 (Fritsch)

• ZrO2 grinding bowl 250ml and grinding balls 5

mm in diameter

• rotational speed: 200

• milling duration: 8 h

• isopropanol

• drying and sieving

Mixtures preparation


E-MRS Fall Meeting


Warsaw, Poland

Spark Plasma Sintering – process parameters

• Pressure: 35 MPa

• Temperature: 1550 °C

• Vacuum

• duration: 10 minutes

The chamber Die assemble


E-MRS Fall Meeting


Warsaw, Poland

Microstructure of Al2O3 base ceramics with addition 2 wt.% of GPLs(4),

homogenised for 8h in planetary mill;


E-MRS Fall Meeting


Warsaw, Poland

Microstructure of Al2O3 base ceramics with addition 2 wt.% of GPLs(4),

homogenised for 8h in planetary mill; TEM, magnification 180 000x


E-MRS Fall Meeting


Warsaw, Poland

Properties

Material

Al2O3 –

initial

Al2O3 +

0.15% GPLs

(4)

Al2O3 + 2% GPLs (4)

⊥

Al2O3 + 2%GPLs

(4)

II

Density

[g/cm3]

3.90 ±0.01

(99%)

3.94 ±0.01

(99%)

3.83 ±0.01

(98%)--

Young modulus

[Gpa]

381 ±8

(98%)

381 ±8

(98%)

307 ±6

(75%)

351 ±3

(85%)

Vickers hardness HV1

[GPa]17.7 ±0.2 15.8 ±0.2 15.5±0.2 16.8±3

Fracture toughness KIc

[MPa∙m1/2]5.6 ±0.2 5.4 ±0.3 5.1 ±0.2 5.2 ±0.2

J. Morgiel, P. Klimczyk, Ł. Major, L. Jaworska, Ł. Maj, T. Cygan, A. Olszyna, TEM investigations of wear mechanism of

Al2O3 and Si3N4 compacts with GLPs additions; Ceramics International, Volume 43, Issue 11, 1 August 2017,

Pages 8334-8342


Physical – mechanical properties

The following test conditions were

established:

Al2O3 ball diameter: 2.0 mm,

applied load: 4 N,

sliding speed: 0.1 m/s,

diameter of the sliding circle: 3 mm,

the sliding distance: 1 000 m,

duration of the test: 10 000 s,

temperatures: RT

Typical ball-on-disc

setup where

• Fn is the normal force

applied on the ball;

• Ft is the friction force

Al2O3/graphene � tribological tests

E-MRS Fall Meeting


Warsaw, Poland

Friction coefficient and specific wear rate for the sample containing 2 wt.% of GPLs(4)

for tests carried out on the surface parallel and perpendicular to the pressing direction.

J. Morgiel, P. Klimczyk, Ł. Major, L. Jaworska, Ł. Maj, T. Cygan, A. Olszyna, TEM investigations of wear mechanism of

Al2O3 and Si3N4 compacts with GLPs additions; Ceramics International, Volume 43, Issue 11, 1 August 2017,

Pages 8334-8342


E-MRS Fall Meeting


Warsaw, Poland

Conclusions

� Despite observed orientation of the graphene platelets, hardness and fracture

toughness measurement values were not strongly dependant on the

measurement direction in relation to the pressing axis

� Mean coefficient of friction for both surface parallel and perpendicular to the

pressing direction was about 0.7

� Specific wear rate of disc was notably smaller in case of surface perpendicular to

the pressing axis


E-MRS Fall Meeting


Warsaw, Poland

Alumina based composites with low electrical resistivity

Drilling using EDM technique

High hardness ceramic materials with low electrical resitivity (< 10 Ω) to forming using

EDM technique

Cutting using EDM technique

E-MRS Fall Meeting


Warsaw, Poland

Materials

Free sintering

parameters

Apparent

Density

Young

ModulusHardness

Electrical

Resistance

temperature [°C]

duration [min][g/cm3] [GPa] HV1 [Ω]

Al2O3 1700 / 60 3.94 390 1700 5·1014

Al2O3+20%Mo 1700 / 60 4.80 350 1442 > 10·106

Al2O3+30%Mo 1700 / 60 5.13 349 1474 4.4

Al2O3+20%Mo 1800 / 60 4.84 364 1431 > 10·106

Al2O3+30%Mo 1800 / 60 5.18 358 1438 3.3


E-MRS Fall Meeting


Warsaw, Poland

Materials

SPS sintering

parameters

Apparent

Density

Young

ModulusHardness

Electrical

Resistance

temperature [°C]

duration [min][g/cm3] [GPa] HV1 [Ω]

Al2O3

+30%Ti(C,N)1650 / 1 4.29 401 2042 1.32·10-1

Al2O3-Ti(C,N)

+5%TiB2

1650 / 1 4.29 407 1966 8.12·10-2

Al2O3-Ti(C,N)

+10%TiB2

1650 / 1 4.29 392 1996 4.28·10-2

Al2O3-Ti(C,N)

+30%TiB2

1650 / 1 4.27 402 2106 1.35·10-2

Al2O3-Ti(C,N)

+50%TiB2

1650 / 1 4.19 414 2226 1.92∙10-2


E-MRS Fall Meeting


Warsaw, Poland

EDM drilling of

Al2O3-Ti(C,N)-TiB2

EDM cutting of

Al2O3-Ti(C,N)-TiB2

P. Putyra, L. Jaworska, M.Podsiadło, J. Laszkiewicz-Łukasik, T.Krzywda, The ceramic materials to forming by EDM

method, The Korean Powder Metallurgy Institute. 2016 ISNNM-2016 The 14th International Symposium on Novel and

Nano Materials, July 3-8 2016


E-MRS Fall Meeting


Warsaw, Poland

it is possible to conclude that the presence of MoO3 phase and a very high

tool life of Al2O3–15 wt.% Mo composite confirms the thesis of good

lubricating properties of MoO3 phase in dry machining conditions.

Al2O3–15 wt.% Mo - Hot Pressing 20MPa, 1350°C, 60 min, atm. argon

K. Broniszewski, J. Woźniak, K. Czechowski, L. Jaworska, A. Olszyna, Al2O3–Mo cutting tools for machining hardened

stainless steel, Wear, Vol.303, Iss. 1-2, 15 June 2013, Pages 87-91

MoO3 structure schemeModel of cutting tool thermal oxidation during machining


E-MRS Fall Meeting


Warsaw, Poland

� Additions of Mo, Ti(C,N), and TiB2 have significant influence on decreasing

electrical resistance and mechanical properties are not changing

� For all kinds presented materials is possible to use EDM technique

Conclusions


E-MRS Fall Meeting


Warsaw, Poland

The aim of our work is to obtain Al2O3-cBN composites with high

hardness and fracture toughness which can be easily produced by

SPS (spark plasma sintering) method.

Potential applications: cutting tools or different small wear parts.

High and low pressure sintering of Al2O3-cBN compositescomparison of two methods:

• HPHT: 7.7 GPa

• SPS: 35 – 75 MPa

Al2O3-cBN composites by HPHT and SPS

P. Klimczyk , M.E. Cura , A.M. Vlaicu , I. Mercioniu , P. Wyżga, L. Jaworska , S-P. Hannula

Al2O3 – cBN composites sintered by SPS and HPHT methods. Journal of the European Ceramic Society 2016 , 36, 7 ,

1783-1789

E-MRS Fall Meeting


Warsaw, Poland

Al2O3 – cBN composites sintered with HPHT and SPS methods

Young's modulus

HPHT 7.5 GPa, 1 min

SPS 75 MPa, 4 min

SPS 35 MPa, 4 min

Density

HPHT 7,5 GPa, 1 min

SPS 75 MPa, 4 min

SPS 35 MPa, 4 min

E-MRS Fall Meeting


Warsaw, Poland

7.5 GPa, 1170 °C, 1 min 7.5 GPa, 1880 °C, 1 min

HPHT


E-MRS Fall Meeting


Warsaw, Poland

75 MPa, 1300 °C, 4 min 35 MPa, 1300 °C, 4 min

SPS


E-MRS Fall Meeting


Warsaw, Poland

Microstructure and phase analysis

Sintering method

(parameters)

Al2O3 alpha c-BN h-BN Al5BO9

HPHT

(7.5GPa, 1174 °C, 1 min)69.4 % 30.5 % - -

HPHT

(7.5GPa, 1883 °C, 1 min)69.2 % 29.2 % 1.3 % -

SPS

(75MPa, 1300 °C, 4 min)68.81 % 28.47 % - 2.72 %

SPS

(35MPa, 1300 °C, 4 min)68.71 % 27.80 % 1.04 % 2.45%

E-MRS Fall Meeting


Warsaw, Poland

Physical and mechanical properties

Sintering method

(parameters)

Density

(relative density)

Young’s

Modulus

(relative Young’s

modulus)

Vickers

hardness

HV1

Fracture

toughness KIC

g/cm3

(%)

GPa

(%)GPa MPa·m1/2

HPHT

(7.5GPa, 1170 °C, 1 min)

3.82 ±0.01

(>99%)

457 ±8

(84%)21.8 ±1.6 -

HPHT

(7.5GPa, 1880 °C, 1 min)

3.78 ±0.01

(98%)

453 ±8

(83%)16.8 ±0.9 8.2 ±0.5

SPS

(75MPa, 1300 °C, 4 min)

3.69 ±0.01

(96%)

433 ±5

(79%)18.6 ±0.7 6.5 ±0.2

SPS

(35MPa, 1300 °C, 4 min)

3.51 ±0.01

(91%)

382 ±6

(70%)16.1 ±1.2 5.9 ±0.5

E-MRS Fall Meeting


Warsaw, Poland

Tribology

Specific wear rate of Al2O3 + 30 vol.% cBN material (disc) obtained by HPHT and SPS

method as the result of sliding contact with the Al2O3 ball (diameter 3.2 mm) under load

of 10N during Ball-On-Disc test.

E-MRS Fall Meeting


Warsaw, Poland

Conclusions

� Sintering temperature for Al2O3 – cBN composites for HPHT method

(1170 °C) is about 100 °C lower than for SPS (1300 °C)

� The microstructures of the investigated samples are homogeneous,

with the components uniformly distributed in the volume of the

composite.

� The composites obtained by SPS have slightly lower density and

Young’s modulus than those obtained by HPHT but their fracture

toughness is still better than for pure alumina.

� The best wear resistance have samples sintered by SPS at 75 MPa.

� There was no observed of significant hBN formation during SPS

processes (only ~1% of hBN at 35 MPa); SPS is a promisingalternative to expensive HPHT in the preparation of CMC’scontaining metastable cBN phase


E-MRS Fall Meeting


Warsaw, Poland

Conclusion

Choosing the method of sintering is determined by the

possibilities and limitations of individual methods but above all

there is the economic calculation

E-MRS Fall Meeting


Warsaw, Poland

CRM-EXTREME

[email protected]

www.crm-extreme.eu

http://www.cost.eu/COST_Actions/ca/CA15102

Acknowledgments

I thank my colleagues from the Institute

of the Advanced Manufacturing Technology for their help

in preparing this presentation

E-MRS Fall Meeting


Warsaw, Poland

Thank you for your attention

Documents

New materials througha varietyof sinteringmethods...framework of the SINTERCER project “Development of a sintering centre and know-how exchange for non-equilibrium sintering methods