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POSSIBILITY OF REACTION POSSIBILITY OF REACTION SYNTHESIS OF INTERMETALLICS SYNTHESIS OF INTERMETALLICS USING CONICALLY SHAPED CHARGEUSING CONICALLY SHAPED CHARGE

*Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan

**Shock Wave and Condensed Matter Research Center, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan

***Asahi-Kasei Chemicals Corp., Chikushino Plant, Chikushino 818-0003, Japan

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Naoyuki WADA*, Kazuyuki HOKAMOTO**, Syoichiro KAI***, Yasuhiro UJIMOTO***

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ContentsContents

Introduction

Experimental

Results and Discussions

Summary

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IntroductionIntroductionAbout Ceramics and Nitrides

Properties of Nitrides

Synthetic methods and Shock Induced Chemical Reaction

Author’s Other Reseach~Wire Explosion Technique~

Research ~Synthesis of Nitrides through the Reaction of a Metal Jet~

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About Ceramics and NitridesAbout Ceramics and NitridesCeramicsCeramicsOxides, Nitrides, Carbides, Borides, etc….

Nitrides, especially titanium nitride (TiN), aluminum nitride (AlN), and titanium aluminum nitride (TiAlN) are studied for their significant characteristics.

Due to ceramic materials wide range of properties, they are used for a multitude of applications. In general, most ceramics are….

Advantages of CeramicsAdvantages of Ceramics

HardWear-resistantBrittleRefractoryThermal insulators

Electrical insulatorsNonmagneticOxidation resistantProne to thermal shock Chemically stable

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Properties of NitridesProperties of Nitrides

AlN

TiN

High melting pointHigh strength Wear resistance High electric conductivity

Coating materialCermet materialHigh heat resistanceDecorative purposes

ApplicationApplicationPropertiesProperties

High thermal conductivityExcellent electrical isolationHigh heat resistanceHigh-corrosion resistance

PropertiesProperties

Electronic substratePower deviceHeatsink

ApplicationApplication

TiAlN

Coating materialMold toolOptical apparatus

ApplicationApplication

High vickers hardness (TiAlN>TiN)High oxidation onset temperatureHigh-corrosion resistance

Powder color Purple / Broun

Vickers hardness 2800 HV

Oxidation temperature 788 ゜ C

Frictional coefficient 0.8

PropertiesProperties

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To be obtained ultra-fine grained structure which is expected to improve the properties of the synthesized materials.

The ultra-fine grained structure in the order of nanometer size can be obtained.

Pressures up to the order of several tens of GPa can be applied.

Synthetic methods and Synthetic methods and Shock Induced Chemical ReactionShock Induced Chemical Reaction

ProblemsLow purity, prolonged heating

Difficult to use NH3 gas

High cost of equipment

Carbothermal reduction-nitridation

Direct nitridation by using NH3

CVD method

Methods of Synthesizing Nitrides

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Shock Induced Chemical Reaction

New Research for Synthesizing has been investigated. New Research for Synthesizing has been investigated.

This is the technique for synthesizing ceramics and intermetallics by using extremely high velocity and pressure and this technique has been investigated to synthesize various intermetallics by researchers by using Gas- gun or explosively accerelated assembly.

試料室火薬室発射管

真空ポンプ

Advantages of Shock Induced Chemical Reaction

Vacuum pomp Target chamber

Barrel Powder chamber

77Author’s Other ReseachAuthor’s Other Reseach~Wire Explosion Technique~~Wire Explosion Technique~

When high current is loaded to wire , it is rapidly heated and changes to plasma. In this state, the reactivity of the excited metal is high, so it is possible to induce reaction with gas.

About Wire Explosion

Assembly used for wire wxplosion

Synthesis of TiN powders through electrical wire explosion in liquid nitrogen*)

Liquid nitrogen was used to react with the exploded Ti wire. Considering the excited condition of the exploded Ti material, it is easy to induce reaction between the dissimilar reactive atoms such as liquid nitrogen.

TiN powders were successfully recovered .Ultrafine TiN particles in the order of 50 nm were observed.

10˚ 20˚ 30˚ 40˚ 50˚ 60˚ 70˚ 80˚

Inte

nsit

y (a

.u.)

2q (Cu-Ka)

TiN

50nm

*)K. Hokamoto, N. Wada, S. Kai et all, J. Alloy. Compd. 485 (2009) 573-576.

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Conical shaped charges are well known for making holes on a thick metal plate. A metal jet formed by an extremely high-velocity material flow having an extremely high kinetic energy is generated ahead of the collision point of the metal cone.

Easy to induce high pressure by using metal jet.

Various intermetallics can be obtained.

Shortening in synthesis time.

The ultra-fine grained structure in the order of nanometer size can be obtained.

Conical Shaped Charge and Metal Jet

In this investigation, an aluminum metal jet was penetrated into liquid nitrogen mixed with titanium powders. The authors tried to synthesize TiN and AlN, TiAlN, and investigate the basic phenomenon from the recovered samples.

New Research New Research ~Synthesis of Nitrides through the Reaction of a Metal Jet~ ~Synthesis of Nitrides through the Reaction of a Metal Jet~

Properties of using Metal Jet for Synthesizing

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ExperimentalExperimentalExperimental Devices

Experimental Method and Conditions

Penetration Experiments

Velocity of Metal Jet

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Experimental DevicesExperimental Devices

Assembly used for recovery experiments

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Details of Experimental devicesDetails of Experimental devices

Electric detonator

Explosive (SEP)

Al cone

a

Metal jet generation partsMetal jet generation parts

Dimensions of Aluminum cone

Thickness 1.2 mm

Angle a 45°

Diameter of charge 33.5 mm

Detonation : Electric detonator (Kayaku Japan Co.)

Explosive : SEP explosive (Kayaku Japan Co.) Detonation velocity 7.0 km/s Density 1300kg/s

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Experimental DevicesExperimental Devices

Assembly used for recovery experiments

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Details of Experimental devicesDetails of Experimental devices

Powder and Liquid container partsPowder and Liquid container parts

Dimensions of SUS 304 pipe

Outside diameter 30 mm

Inside diameter 17mm

Height 40 mm

Spherical titanium powder : Average diameter 45m

SUS304 pipe

Ti powders

Liquid nitrogen

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Experimental Method and ConditionsExperimental Method and Conditions

Assembly used for recovery experiments

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・ The explosive SEP was detonated by electric detonator placed on the upper side of the cone.

・ After the detonation, an aluminum metal jet was penetrated into liquid nitrogen mixed with titanium powders.

・ In this state, ceramics like TiN or AlN, TiAlN will be generated.

ExperimentExperiment

Details of aluminum cone

No.a (de

g.) (m

m)distance d (mm)

Mass of Explosive (g)

145 33.5

2024g

2 10

Experimental conditions

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Schematic illustration of penetration examination

a45°

SUS plate

Mild steel

Explosive (SEP)

Al cone

Electric detonator

a

Penetration ExperimentsPenetration ExperimentsPrior to the recovery experiments, the assembly was used for penetration experiment.

Two kinds of penetration experiments were done to compare.

No.

a (deg.)

(mm)

Mass of Explosive (g)

Test plateThickness of Plates

(mm)Numbers of plates

penetrated

1 4533.5

24 Stainless steel plate

20 (10layers of plates,

each of 2mm thickness)

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2 60 20 8

a60°

Conditions of penetration experiments and its results

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The velocity of the metal plate Vp was estimated based on the Gurney equation expressed as follows,

E : Gurney energy

In the case of SEP, E=2.16×106 J/kg 2)

R : the mass ratio of explosive c and metal plate m

R=c / m

Then, the velocity of the metal jet Vj is estimated based on the Brikhoff’s equation 3) as follows

Explosive (SEP)

Density(kg/m3) 1310

Velocity(m/s) 7000

Al

Density(kg/m3) 2700 Using the equation, the velocity of the aluminum jet was estimated as…

Vj = 6000 m/s

Cross section diagram of metal jet generation device

The velocity of the jet is estimated based on a simple geometrical relationship as illustrated in Figures.

Solid state properties

Velocity of Metal JetVelocity of Metal Jet

Geometrical relationship for estimation of jet velocity.

453

2

2 2/1

2RRREVp

2tan

)2/cos(sin

2/cossin

βγβ

γβ

pj VV

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Results and DiscussionsResults and DiscussionsExperiment #1 (d = 20mm)

Experiment #2 (d = 10mm)

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Appearance and SEM images

X-ray Diffraction Pattern

Appearance and Optical Microscope Images

X-ray Diffraction Pattern

SEM Images

EPMA Results

Process of Reaction

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Experiment #1 (d = 20mm)

Appearance and SEM Images

X-ray Diffraction Pattern

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Broun colored powders were recovered.

From SEM images, it seems that an aluminum droplet was trapped on a spherical titanium powder.

Results ~Experiment #1~Results ~Experiment #1~Appearance and SEM imagesAppearance and SEM images

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10m

Appearance of recovered powders (a) and its SEM image (b).

(a) (b)

Experiment #1 (d = 20mm)

1818Results ~Experiment #1~Results ~Experiment #1~X-ray diffraction patternX-ray diffraction pattern

Experiment #1 (d = 20mm)

X-ray diffraction pattern (Cu-Ka) for recovered powders.The XRD pattern shows the peak of Ti and Al, and no reacted product was confirmed by this experiment.

It is considered that the reaction was not induced due to the decrease in the velocity of the metal jet during relatively long travelling distance in air.

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Experiment #2 (d = 10mm)

Appearance and Optical Microscope Images

X-ray Diffraction Pattern

SEM Images

EPMA Results

Process of Reaction

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Small blocks were recovered, and the blocks were small fragments in the order of several mm in length.

It is confirmed that the cross-section contains many pores. These pores are formed during the cooling from the molten phase.

Results ~Experiment #2~Results ~Experiment #2~ Appearance and Optical Microscope ImagesAppearance and Optical Microscope Images

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Appearance of small blocks recovered (a) and its Microstructure of cross-section (b).(a) (b)

Experiment #2 (d = 10mm)

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X-ray diffraction pattern (Cu-Ka) for recovered block.

Results ~Experiment #2~Results ~Experiment #2~X-ray diffraction patternX-ray diffraction pattern

The peaks of TiN and TiAlN are confirmed. TiAlN is identified as Ti2AlN and Ti3AlN.

It is interesting to note that aluminum is not the major component of the reaction products even though an aluminum jet was used.

Experiment #2 (d = 10mm)

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About backscattered image It illustrates the distribution of the elements where bright area is composed of heavy element(s) and dark area includes light element(s).

SEM image of recovered block (a) and its backscattered electron image (b), enlarged backscattered image (c) (b)(a) (c)

Since the bright region is composed of heavy element(s), such region close to the central cavity seems to be TiN. The other area close to the edge of a block is considered as TiAlN.

Experiment #2 (d = 10mm)

Results ~Experiment #2~Results ~Experiment #2~SEM ImagesSEM Images

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PositionNo.

Ti content(at %)

Al content(at %)

N content(at %)

1 40.30 4.07 55.632 60.86 18.22 20.92

Central area is composed of TiN and the other area is composed of TiAlN whose composition is closer to Ti3AlN.

The area composed of Ti2AlN is not clearly confirmed because of the slight difference in the chemical composition in the area containing Ti, Al and N2.

Since TiAlN was confirmed especially in the edge of the block, the location should be closer to the central axis of the powder container.

SEM

1

2

Ti

50m

Al

N

Results ~Experiment #2~Results ~Experiment #2~EPMA ResultsEPMA Results

Experiment #2 (d = 10mm)

Chemical components measured by EPMA for recovered block.

Mapping of elements for recovered block taken by EPMA

24Results ~Experiment #2~Results ~Experiment #2~Reaction processReaction process

It is considered that the aluminum jet plays a role to ignite a sustainable reaction between the components placed at the position based on the SHS (Self-propagating High-temperature synthesis) process.

During the cooling from liquid, the area was separated into small fragments (blocks) and central and other cavities are formed by rapidly cooling process.

Experiment #2 (d = 10mm)

Al jet

Ti powders

LN2

Ti-Al-N reacted area

Propagation of reaction between Ti and LN2

TiN Ti-Al-N

1) 2)

3) 4) Cooling

PoreCrack

Reaction

Cooling

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Experiment #2 (d = 10mm)

Results ~Experiment #2~Results ~Experiment #2~Micro Vickers HardnessMicro Vickers Hardness

Area Average Hardness Range

Bright (TiN) 767 HV 648 HVmax – 839 HVmin

Dark (TiAlN) 1067 HV 867 Hvmax – 1219 HVmax

The average micro-Vickers under load 0.098N (10g) was in the order of 650 – 1200 HV.

These values are slightly lower than the reported data which may be caused by the presence of the cavities in the bulk region recovered after cooling from molten phase.

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SummarySummary

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SummarySummary

A new method to synthesize nitride ceramics using conical shaped charges is proposed and the possibility to induce chemical reaction of the elements is demonstrated.

An aluminum cone was highly accelerated as metal jet in the order of 6 km/s and collided with liquid nitrogen mixed with titanium powders.

Under a moderate condition, some small blocks having high hardness were recovered and the blocks were composed of titanium nitride and titanium-aluminum nitrides formed by chemical reaction.

The reaction process was discussed based on the chemical component analysis at different positions in the cross-sectional area.

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Thank you for your kind attention!Thank you for your kind attention!