for Reactive and Refractory Metals
Ceramic Free Metal Powder Production 2
Introduction
Reactive alloys can not be melted and processed in ceramic crucibles due to the reactions between the melt and the ceramic lining. Also ceramic melting for refractory alloys is not possible due to the high melting point of these alloys.
In order to overcome the "ceramic problem” it is necessary to use melting techniques and melt nozzle systems where the melt is not in contact with ceramic lining materials at all. For this reason, ALD Vacuum Technologies AG has developed melting processes and nozzle systems which enable to melt and atomize reactive or refractory alloys in a ceramic-free environment.
Applications
Applications for ceramic-free powders are sput-ter target production, laser sintering, MIM for medical parts and protective coatings. But extremely pure metal alloys are also needed for the production of highly stressed compo-nents in aerospace and aviation industry.
These powders have to fulfill highest quality criteria such as:
n Spherical Shape
n High Cleanliness
n Rapid Solidification
n Homogeneous Microstructure Materials
Typical materials which need ceramic-free
production processes are for example Ti,
TiAl, Zr, Nb, FeGd and FeTb.
Process
High purity ceramic-free metal powders can
only be produced via atomization in a high
purity process atmosphere, i.e. under Argon,
Helium or Nitrogen. For the atomization a
specially designed gas nozzle is used, to
achieve a high yield of fine powder. The
yield of fine powder is substantially higher
compared with rotary atomization processes
(i.e. PREP).
The melting processes which are applied to
ceramic-free metal powder production can
be divided into:
n Melting without any crucible
(EIGA) using pre-alloyed electrode
feedstock material
n Melting using a watercooled
copper crucible (PIGA, ESR-CIG,
VIGA-CC) using typical charging
materials
The Atomization System
Every ceramic-free melting process
can be combined with ALD’s modular
atomization system components, which have
been proven in daily powder production
operation for over 30 years.
Common general features of ALD’s atomiza-
tion systems are:
n High operational flexibility
n High degree of vacuum tightness
n High separation efficiency of the
cyclone system
n Good accessibility for cleaning
and maintenance
n Modular Design
EIGA 50/100 -
Electrode Induction-Melting Gas
Atomization
The EIGA system 50 /100 applies a
crucible free melting & atomization
technique.
The EIGA process uses pre-alloyed rods (cast,
remelted or sintered) as the
electrode feedstock material. The melting of
the feedstock electrode is accomplished by
lowering the slowly rotating electrode into a
conical induction coil. The stream of molten
metal flows directly into the atomization
nozzle system where it is atomized by a high
kinetic energy inert gas jet.
The feed rate as well as coil design and electric
process parameters can be optimized with
regard to the feedstock material.
Additionally it has to be emphasized, that
nearly every metal can be inductively melted
and atomized with the EIGA system 50/100,
resulting in a broad range of potential
applications. The melting and atomization
process can be visually observed through sev-
eral view ports.
A quasi-continuous production mode can be
realized by a load lock magazine which is
flanged on top of the EIGA melting chamber.
n EIGA 100mm Ti
(courtesy of Helmholtz-Zentrum Geesthacht)
3
EIGA PIGA ESR-CIG VIGA-CC
n Ti grade5 EIGA powder
(courtesy of Helmholtz-Zentrum Geesthacht)
n Feedstock material in various dimensions
can be processed and atomized in the EIGA
Niob-Alloy
Niob-Alloy
Titanium-Alloy
Particle Diameter (µm)
1101001000
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reactive metall
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The ceramic-free melting processes of ALD, using water cooled copper cru-
cibles for melting and copper based melt nozzle systems, have already
been implemented for the production of reactive powders as well as for the
ceramic-free atomization of superalloys.
P lasma M elting I nduction G uiding G as A tomization - PIGA
Plasma melting torch on top of a water cooled copper crucible. The
crucible bottom is directly connected to an inductively heated discharge
nozzle system. This nozzle system is called C old wall I nduction G uiding
(CIG) system, which guides the metal stream ceramic-free into the
atomization gas nozzle.
E lectro-S lag R emelting C old wall I nduction G uiding - ESR-CIG
ESR melting is used for the refining of superalloys and high grade steels.
ESR-CIG enables to combine the ESR refining melting step with the benefits
of the ceramic free CIG system.
V acuum I nduction M elting G as A tomization based on C old W all C rucible
Technology - VIGA-CC
Cold Wall Crucible Technology is used for the production of Ti- or TiAl
based alloys. The VIGA-CC combines a bottom pouring cold wall crucible
with a ceramic free CIG system.
Ceramic-Free Melting System without Crucible Ceramic-Free Melting Systems with Watercooled Copper Crucibles
M e t a C o m /E i g a _e /05.11
n EIGA 50 - Electrode Induction Gas Atomizer for Reactive and Refractory Metals n Cyclone for separation of the atomized powder with powder collecting container
The Process Control System
The evacuation, melting and atomizing processes are monitored and controlled by means of a state-of-the-art PLC control system.The control system enables on-line process monitoring, data-logging and trend analysis.Besides the level of system and process know-how in the field of metal powder technology, the reputation of ALD Vacuum Technologies rests squarely on this added factor of process control.
Great Britain
ALD Vacuum Technologies Ltd.First Floor
276 High Street
Guildford, Surrey GU 1 3JL, UK Phone +44 (1483) 45 44 34e-mail:uk
Russia
ALD Vacuumyje Technologii OOO ul. Bolschaja Ordynka 40, str. 2109017 Moskau, Russia Phone +7 (495) 787 6733e-mail:ald@metallurg.ru
ALD Vacuum Technologies GmbH Wilhelm-Rohn-Strasse 35D-63450 Hanau, Germany
Phone:+49 (0) 6181 - 307-0Fax:+49 (0) 6181 - 307-3290e-mail:solar@ald-vt.de Internet:www.ald-vt.de
China
ALD Liaison Office
c/o C&K Development Co., Ltd.Rm. 1102, South Office Tower Hong Kong Plaza
283 Huai Hai Zhong Rd. Shanghai, 200021, China
Phone +86 (21) 63 85 - 55 00e-mail:ald@ald-vt
Far East
ALD Thermo Technologies Far East Co., Ltd.10F . Shinjuku Nomura Bldg.
1-26-2 Nishi-Shinjuku, Shinjuku-Ku Tokyo 163-0558, Japan
Phone +81 (3) 33 40 37 26e-mail:Peter.Lang@ald-vt.de
USA / Canada
ALD Vacuum Technologies, Inc.18, Thompson Road
East Windsor, CT 06088, USA Phone +1 (860) 386 72 - 27e-mail:info@ald-usa

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