Publikationen

Stellite bearings for liquid Zn-/Al-Systems with advanced chemical
and physical properties by Mechanical Alloying and Standard-PM-Route –
Part I

H. Zoz, H. Ren

H. Zoz, H. Ren, R.
Reichardt

Recycling of EAF dust by
semi-continuous high kinetic process

^1-3
H.
Zoz,
⁴ G. Kaupp, ¹ H. Ren, ⁵ K. Goepel, , ³
Z. Tian, ⁴M. R. Naimi-Jamal and ² D.
Jaramillo V.

¹
Zoz GmbH, D-57482 Wenden, Germany

²
CIITEC-IPN, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

³
CISRI – Advanced
Technology & Materials Co., Ltd, Beijing 100081, P. R. China

⁴
University of Oldenburg, D-26111 Oldenburg, Germany

⁵

Relux Entsorgung GmbH & Co. KG, D-32549
Bad Oeynhausen, Germany

The horizontal high energy rotor ball mill (Simoloyer^®)
is used to break and activate dry solids. It is used for dry-milling
and in the vertical mount for wet-milling in leaching processes.
Technical electric arc furnace (EAF) dust with high contents of zinc
oxide, zinc ferrite and magnetite is efficiently separated by
ambient temperature leaching. The process shows promise for
industrial application.

High Performance Cements and Advanced Ordinary
Portland Cement Manufacturing by HEM- Refinement and Activation

^1-3
H. Zoz,
² D. Jaramillo V., ³
Z. Tian,
⁴ B. Trindade, ¹ H. Ren, ⁵ O. Chimal-V
and ⁵ S. Diaz de la Torre

¹
Zoz GmbH, D-57482 Wenden,
Germany

²
ESIQIE, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

³
CISRI, Powder Metallurgy &
Environmental Technology Div., Beijing 100081, P.R. China

⁴
FCTUC – University of
Coimbra, P-3030 Coimbra, Portugal

⁵
Advanced
Materials Research Center CIMAV S.C., Chihuahua CP 31109, Mexico

Ordinary
Portland Cement (OPC) is the material most widely used in construction
industry all over the world and therefore consumed in super large
volume. This causes general interest in improving this product with
respect to materials properties. Compared to the raw material cost, the
manufacturing cost is energy intensive and therefore cement industry has
been and is interested in improvements in the efficiency of their
milling operation and their rotary kilns.

If High
Energy Milling (HEM) is applied for the grinding of cement, this can
lead to substantial refinement (< 2 µm) and mechanically activation of
the powder particles that in conventional material exhibit a particle
size in the order of 50 µm.

Earlier
work and preliminary studies have shown that this can result in a faster
setting time, a faster curing time and in increased mechanical
properties. Due to the far shorter grinding process at far higher energy
efficiency, due to an expected reduced firing temperature in the
processing and finally due to an expected significant saving in
production space for the grinding step, an economically advanced
manufacturing process of cement seems to be offered by HEM.

Due to a
tremendous refinement into submicron range at high active surface, the
material can result into a super fast setting cement (SFC

»
3 min) where this feature being available for repair-work of concrete
constructions would also lead to an advanced product application which
would be the first appliance imagined for short term range. Later this
maybe spread out by reduced construction dimensions and faster building
due to increased mechanical properties.

The key
question if HEM is available and can be scaled up for this kind of super
large volume application can be carefully answered positively since the
high kinetic semi-continuously processing route based on a carrier-gas
in compression mode has been introduced.

The present paper reviews the preliminary
studies, explains the novel technique and suggests the route into
commercial application. Particular attention is paid to wear results
with an applied Si₃N₄-grinding unit where no
substantial wear was found after 4000 h of operation.

Reactive Dry-Milling for Environmental Protection

-encouraging industrial applications for High Kinetic
Processing-

G.
Kaupp ¹, M. R. Naimi-Jamal ¹, H. Ren ²
and H. Zoz ^2,3

¹
University of Oldenburg, D-26111 Oldenburg, Germany

²
Zoz GmbH, D-57482 Wenden, Germany

³
ESIQIE, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

The Reactive
(dry-) Milling technique [1] is still not widely used, even though
mechanical alloying [2-4] has a long tradition and inorganic or more
recently organic chemical syntheses are known to proceed to
completion without producing wastes [5]. These favorable findings
contrast solution reactions that tend to be incomplete and produce
side reactions with the necessity of waste producing purifying
workup that is in most cases much more expensive than the synthetic
step. The alternative by very high temperature syntheses in
inorganic solid or melt reactions requires much energy which can be
saved if reactive milling succeeds at ordinary temperature. The
nanoscopic nature of solid-state chemical reactions has recently
been studied in numerous organic solid-state reactions using
supermicroscopic techniques like atomic force microscopy (AFM),
scanning near-field optical microscopy (SNOM) and
nanoindentation/nanoscratching. A consistent mechanistic scheme
emerged for the non-tribochemical reactions with far-reaching
molecular migrations within the crystal along “easy” paths [5].
While the three-step mechanism of phase rebuilding, phase
transformation and crystal disintegration is secured for molecular
crystals, organic polymers or infinite inorganic covalent crystals
undergo tribochemical reactions by mechanical breakage of covalent
bonds. The extremely unsaturated fresh surfaces which occur upon
cleavage of the crystals cause local plasmas which allow all kinds
of chemical reactions at low temperature [6]. There may be
borderline cases between these different mechanisms with salts and
metals, but normal non-polymeric organic molecules cannot break
covalent bonds upon mechanical interaction by milling unless very
high forces are applied with Bridgman anvil type equipment [7] The
latter reactions are without preparative use. We describe here
technical applications of reactive milling in the different fields.


 

---

HKP using Carrier-gas Assisted Discharging

^1,3
H. Zoz,
¹ H. Ren, ¹ H U. Benz,
²
T. Suzuki,
²
H. Ikehata and
²
T. Saito

¹
Zoz GmbH, D-57482 Wenden,
Germany

²
Toyota Central R&D LABS.,
INC., Nagakute, Aichi 480-1192, Japan

³
ESIQIE, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

The
Simoloyer-mill is well known as a horizontal-rotary-ballmill that allows
high-kinetic energy impact at relative velocity of the grinding media up
to 14 ms^-1.

This
often leads to very short processing times in the range of some seconds
to some minutes for particle-size-reduction, particle-shape-deformation
and reactive-milling.

If the
device is applied for a batch-process, these short processing times
result in a major barrier for the scaling up res. the commercialization
of the process. The reason is the needed discharging procedure that
often needs similar or longer time sometimes even at similar velocity.
Thus the material that is discharged e.g. after 1 minute is expected to
be different from the material discharged after 2, 3, 4 etc. minutes.

To solve
this problematic, a carrier-gas-discharging unit TGD20 has been
developed to rapidly unload processed material out of the vessel of a
CM20-Simoloyer (20 liter chamber volume) at low rotational speed in a
closed gas circuit under severe oxygen measurement and control.

The
present paper explains the new device and describes the initial testing
after particle size reduction of a glass-system under air as well as
soft-MA of a metal-system under inert gas.

Results
will be given in terms of powder yield/time relation, different
gas-flow-velocities and rotational speeds. The materials were
characterized by SEM and laser diffraction.

Comparative routes of solid-solution-formation by MM
of Ag-70Cu (at%)

^1,2
H. Zoz,
²
I. Vernet and
²
D. Jaramillo V.

¹
Zoz GmbH, D-57482 Wenden, Germany

²
ESIQIE, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

The
solid-solution-formation (SSF) of Ag-70Cu (at%) has been chosen as the
goal to be achieved by Mechanical Milling (MM) in a SPEX8000D-Mixer/mill
and alternatively by a Simoloyer CM01-2l. In case of the
SPEX-Mixer/mill, this is reached after about 43.2 ks, in case of the
Simoloyer after 18 ks.

The
observation, that processing at given parameters in the Simoloyer leads
to a flaky geometry already after 0.060 ks versus the SPEX-Mixer/mill
after 10.8 ks or not at all is concluded to be caused by a higher
collision rate. In result this matches to the long known attempt, that
the collision itself is the main event for energy transfer in MA.
Additionally in case of the Simoloyer, Cycle Operation has been applied
which results here in rapid flaking with quasi-disappearing ductility
followed by shear-stress to break the flaky structure repeatedly.

Since a
higher collision rate versus shear and friction effect is expected to
cause less abrasive wear on the milling tools, the Fe-contamination of
both systems was investigated and showed a lower contamination for the
Simoloyer which matches to the expectation, too.

Material’s characterization is given by SEM, XRD and TEM.

Solid-solution-formation by MM of the Ag-70at%Cu
alloy

^1,2
H. Zoz,
²
S. Morales and
²
D. Jaramillo V.

¹
Zoz GmbH, D-57482 Wenden,
Germany

²
ESIQIE, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

High-speed steel is the most superior tool steel in terms of wear
resistance at high temperature.

In order
to further improve materials properties, conventional HSS-powder (<76µm)
has been mechanically milled by a Planetary Ball Mill (medium kinetic
system) and alternatively by a Simoloyer (high kinetic system) in order
to reduce particle size and in particular the grain size of the powder
material. Consolidation has been done by Spark Plasma Sintering in order
to maintain a fine structure of the material.

In the
Planetary Ball Mill, 25 g of HSS-powder was milled for 720 ks (200h) and
resulted in a particle size of <15µm at an average grain size of 10nm.
Similar results in the Simoloyer were achieved after 72 ks under higher
powder load.

The
SPS-sintered parts were investigated by hardness, the characterization
of the powder is given by XRD, SEM and laser diffraction.

Alternative Mechanical Milling routes for
grain-refinement of conventional High-Speed Steel powder for later
consolidation by SPS

^1,3H.
Zoz
,
²K.
Ameyama, ^1,2
S.
Umekawa,
¹
H. Ren and
³
D. Jaramillo V.

¹
Zoz GmbH, D-57482 Wenden,
Germany

²
Ritsumeikan
University, 525-8577
Kusatsu,
Japan

³
ESIQIE, National Polytechnic
Institute, Mexico City, DF 07300, Mexico

High-speed steel is the most superior tool steel in terms of wear
resistance at high temperature.

In order
to further improve materials properties, conventional HSS-powder (<76µm)
has been mechanically milled by a Planetary Ball Mill (medium kinetic
system) and alternatively by a Simoloyer (high kinetic system) in order
to reduce particle size and in particular the grain size of the powder
material. Consolidation has been done by Spark Plasma Sintering in order
to maintain a fine structure of the material.

In the
Planetary Ball Mill, 25 g of HSS-powder was milled for 720 ks (200h) and
resulted in a particle size of <15µm at an average grain size of 10nm.
Similar results in the Simoloyer were achieved after 72 ks under higher
powder load.

The
SPS-sintered parts were investigated by hardness, the characterization
of the powder is given by XRD, SEM and laser diffraction.

¹ H.
Ren, ^{1, 3}
H. Zoz, ²
G. Kaupp and ²
M. R. Naimi-Jamal

¹ Zoz GmbH, D-57482
Wenden, Germany

²
University of Oldenburg, D-26111
Oldenburg, Germany

³ ESIQIE, National
Polytechnic Institute, Mexico City, DF 07300, Mexico

Horizontal high energy ball-mills are known from academic
as well as industrial applications in mechanical alloying (MA)
[1-4], high energy milling (HEM) [5] and reactive milling (RM) [6].
They supply the highest relative velocity of grinding media, which
leads to an intensive grinding effect, short process times and a
lower contamination of the processed powders by the milling tools
due to a process that is based more on the collision of the grinding
media than on their shear and friction interaction. Since the
grinding media are accelerated by a horizontally arranged rotor
inside the grinding vessel, these devices have the additional
advantage of not moving unnecessarily any large masses like e.g. the
entire chamber/mill in the cases of vibration ball-mills. The
systems are presently available at 0.5 to 400 L grinding chamber
capacity [7] and larger volumes seem to be possible. Various
existing applications for the environment include MA of different
metals and/or ceramics [8], decontamination of dangerous residues by
using the tribochemistry of milled sand (SiO2) and waste-free
organic chemical solid-state syntheses with 100% yield [9]. In
particular these procedures are economically and ecologically
favorable as in most cases they can be operated semi-automatically
if they are combined with a continuous or semi-continuous
(auto-batch) powder separation system. We report here on some
applications of HEM/RM.



 

---

Mechanically alloyed SiC composite powders
for HVOF applications

B.
Wielage¹, J. Wilden¹, T. Schnick¹, A.
Wank¹, J. Beczkowiak²,
R. Schülein³,
H. Zoz^4,5 H. Ren⁴

¹
Institute of Composite Materials, Chemnitz
University of Technology, D

²
Praxair Services GmbH,
Wiggensbach, D

³
Euroflamm GmbH, Bremen, D

⁴
Zoz GmbH, Wenden, D

⁵ESQIE,
National Polytechnic Institute, México City, DF 07300

In
general component surfaces are exposed to a combination of detrimental
mechanical, tribological, corrosive and thermal effects. The stress
induced at the component surface causes a degradation of
properties or in the worst case a complete failure.
Surface technologies enable the deposition of protective coatings. In
many cases the complex surface demands can only be met by the
application of composite materials.
HVOF spraying is actually one of the advanced surface technologies for
the production of coatings against wear and corrosion with respect to
process control and economic issues. Due to the flexibility of the
process and the diversity of applicable feedstock HVOF has reached high
acceptance for industrial applications.
In consideration of increased coating efficiency, the reduction of the
weight of coated volume and cost saving leads to the effort to optimize
the spray facilities and on the other hand to the development of new
consumables for expanded applications.

Simoloyer®: major characteristics and features

H. Zoz

Zoz GmbH, D-57482 Wenden,
Germany

abstract

¹

Zoz GmbH, D-57482 Wenden, Germany
²

Pfaudler Werke GmbH, D-68723 Schwetzingen, Germany
³


Degussa-Hüls AG, D-63457 Hanau, Germany
⁴

Wendel
GmbH, D-35683 Dillenburg, Germany
⁵

Miele &
Cie. GmbH & Co., D-33332 Gütersloh, Germany

Coatings of Enamels, Glass
Fluxes and Glaze Frits are used in large quantities all over the world.
The main application areas might be divided into household appliances,
sign & signal (& arts), anti-corrosives and electronics. The
conventional processing route of the rapidly quenched glass-material is
mechanical grinding in a low kinetic (drum-) ball-mill down to fine
solid particles in a liquid base (slurry).
The present paper describes the application of High Energy Milling (HEM)
which is usually used to perform Mechanical Alloying (MA), Reactive
Milling (RM) as well as particle deformation and processing directly by
HEM to produce nanocrystalline and amorphous materials, ductile metal
flakes and others.

The reported preliminary
testing has been performed in a lab-scale system (Simoloyer CM01-2l) in
dry and batch-processing route. The results do show that the HEM-route
leads to finer powder (average size about 5 µm) in a very short time (<
2 minutes).
Based on the short processing time, a semi-continuously route has been
considered to be applied. The initial testing in continuously operation
by depression did lead to a particle-size D50-value of 6µm after a
processing time of 20-40 seconds where the starting particle size was
about 6 mm. Here the comparison leads to 3 times finer particles in a
500-600 times shorter process which will also be explained due to an
insitu classification/separation.
The even more prospective route, the semi-continuously operation mode by
compression, where a carrier-gas-system is fed outside the
processing-chamber with starting material and cycled in a closed
gas-system will be discussed here.
Due to the tremendous decrease of processing time and it’s principle
based on collision of grinding media, contamination by the milling tools
might be controlled perfectly.
Together with a high possibility of insitu adaptation of further
follow-up processing steps, this dry and high kinetic processing route
promises an increase of quality at a decrease of producing cost and an
increase of product flexibility at the same time.
Considering that the future target for the particle size distribution
will become < 10 µm, probably at a narrower size distribution, this
potential appears even more interesting.
The characterization of materials has been done by scanning electron
microscopy and particle size distribution measurement by laser
diffraction, results of melting tests are discussed.

Stellite bearings for liquid Zn-/Al-Systems
with advanced chemical and physical properties by Mechanical Alloying
and Standard-PM-Route
– Part I

H. Zoz,
H. Ren, R. Reichardt,
H.U. Benz, K. Hüttebräucker, L.
Furken

An important
business-field of world-wide steel-industry is the coating of thin
metal-sheets with zinc, zinc-aluminum and aluminum based materials.
These products mostly go into automotive industry, in particular for the
car-body, into building and construction industry as well as household
appliances.
Due to mass-production, the processing is done in large continuously
operating plants where the mostly cold-rolled metal-strip as the
substrate is handled in coils up to 40 tons unwind before and rolled up
again after passing the processing plant which includes cleaning,
annealing, hot-dip galvanizing / aluminizing and chemical treatment.
In the liquid Zn, Zn-Al, Al-Zn and Al-Si bathes a combined action of
corrosion and wear under high temperature and high stress onto the
transfer components (rolls) accounts for major economic losses. Most
critical here are the bearing systems of these rolls operating in the
liquid system. Rolls in liquid system can not be avoided as they are
needed to transfer the steel-strip into and out of the crucible.
Since several years, ceramic roller bearings are tested here, however,
in particular due to uncontrollable slag-impurities within the hot bath,
slide bearings are still expected to be of a higher potential.
The today’s state of the art is the application of slide bearings based
on Stellite® against Stellite which is in general a 50-60 wt% Co-matrix
with incorporated Cr- and W-carbides and other composites.
Indeed Stellite is used as the bearing-material as of it’s chemical
properties (does not go into solution), the physical properties in
particular with poor lubricating properties are not satisfying at all.
To increase the sliding behavior in the bearing system, about 0.15-0.2
wt% of lead has been added into the hot-bath in the past. Due to
environmental regulations, this had to be reduced dramatically. This
together with the heavily increasing production rates expressed by
increased velocity of the substrate-steel-band up to 200 m/min and
increased tractate power up to 10 tons in modern plants, leads to life
times of the bearings of a few up to several days only.
To improve this situation, the Mechanical Alloying (MA) technique is
used to produce advanced Stellite-based bearing materials. A lubricating
phase is introduced into Stellite-powder-material by MA, the
composite-powder-particles are coated by High Energy Milling (HEM) in
order to produce bearing-bushes of approximately 12 kg by Sintering,
Liquid Phase Sintering (LPS) and Hot Isostatic Pressing (HIP).
The chemical and physical behavior of samples as well as the bearing
systems in the hot galvanizing / aluminizing plant are discussed.
Dependencies like lubricant material and composite, LPS-binder and
composite, particle shape and PM-route with respect to achievable
density, (temperature-) shock-resistibility and corrosive-wear behavior
will be described.
The materials are characterized by particle size analysis (laser
diffraction), scanning electron microscopy and X-ray diffraction,
corrosive-wear behavior is determined using a special cylinder-in-bush
apparatus (CIBA) as well as field-test in real production condition.
Part I of this work describes the initial testing phase where different
sample materials are produced, characterized, consolidated and tested in
the CIBA under a common Al-Zn-system. The results are discussed and the
material-system for the large components to be produced for the field
test in real production condition is decided.

Processing of Ceramic Powder using High
Energy Milling (HEM)

H. Zoz, H. Ren

The consolidation behavior of metallic and ceramic powders is
considerably influenced by their particle size. For some special
applications fine powders with a particle size of a few microns (or even
nanometers) are required to improve the mechanical properties of
products and facilitate following processing, e.g. a better fluidity of
the powder by injection or a better sintering activity due to their
large free surface with an elevated particle contact density. A dry
milling process is especially desired because any fluid process control
agent (PAC), such as water or alcohol, is regarded to brake the milling
unnecessarily. The traditional equipment used for the processing of
ceramic powder are the drum-ball-mills which are characterized as low
energetic process with a specific energy of 0.01-0.03 kW/l. The terminal
size with a diameter d = 15-20 µm by a dry milling condition could be
reached and by wet milling condition d = 10 µm. Furthermore, a long
duration of the procedure of up to a few days is required and a
contamination of ferrous metals from the grinding parts is not to be
neglected. High Energy Milling is an effective and economical method
producing fine ceramic powder by using a high energy ball mill, the
Simoloyer. The principle of the High Energy Mill is based on a
horizontally borne rotor in a strong design which allows an energy
transfer in a homogeneous and high efficient way from supplied power to
kinetic energy of balls (grinding media). The milling balls are
accelerated by the rotating rotor and collide with each other at a
relative velocity up to 14 m/s. Due to a high energy contribution with a
specific energy of 0.55 – 3 kW/l, the milling processing is more
efficient than one of the conventional mills. This work presents the
milling tests of ceramic or intermetallic powders, such as Al2O3, SiC,
Quartz, ZrSiO4, TiC, NiAl, using a laboratory scale grinding unit with a
two liters milling volume. The milling parameters are optimized and
presented. Characterization of as-milled powders were carried out by
SEM. The investigations reveal that, fine powder with particle size d <
2 µm after 2 hours milling time could be obtained under dry milling
conditions by the use of the High Energy Ball Mill.

Energy Balance during Mechanical Alloying,
Measurement and Calculation Method supported by the MALTOZ®-software

H. Zoz, H. Ren, R. Reichardt

Mechanical Alloying [1,2],
High Energy Milling [3] and Reactive Milling [4] are well-known
techniques used in powder metallurgy. The main processing principle is
the energy transfer into the powder by highly kinetic ball collisions
[5,6]. However there are only a few applications that have been
commercialized in the past. One important limit is always the difficulty
of determining the influence of the various parameters in the process.
Most of the work there is still done by trial and error. Since the Cycle
Operation Procedure [7,8,9] has been introduced for the processing of
ductile materials, the MALTOZ®-software became an indispensable
requirement to control the processing. The process itself is not under
control today, only but important parts are, so that an acceptable
reproducibility is given. Since MA, HEM and RM is approaching many
industrial fields today, like the production of metal flakes [3], of
electrical contact materials [4] and hydrogen storage materials [10],
there is a high demand of determination the energy input not only into
the system (total energy consumption), it is of major interest to
quantify the part of energy that is transferred into the powder. To
increase the understanding of processing, the number of single
parameters that can be controlled must be increased. If a parameter can
not be controlled, the attempt is to record the corresponding data in
order to find a solution to control it in the future. Following this
philosophy, a module to calculate the energy balance during processing
[3] is implemented to the MALTOZ®-software which is controlling the
equipment for the powder production. To quantify the transmitted energy
from the milling device into the powder, which is mainly plastic
deformation and surface energy, it is necessary to determine the heat
transfer due to friction effects in the process (grinding media) as well
as in the machine (bearing, seals, etc.). Other unknown energy factors
are noise as well as heat of powder due to powder reactions. Measurement
equipment for the process temperature, the grinding unit and is cooling
system as well as the power and speed of the motor of the milling-system
is used. The difference between the energy balance of a milling test
with and without powder eliminates the process independent energy
consumption. The result is the energy consumption of the powder as a
function of milling speed and milling time. An application for this
energy balance is a MA-process with milling times of hours or days,
because the system is able to calculate the power consumption of the
powder. In future milling devices equipped with the energy balance
system are able to stop themselves when the energy transfer from the
milling device to the powder ended.

Ductile Metal Flakes based on [Au], [Ag],
[Al], [Cu], [Ti], [Zn] and [Fe] Materials by High Energy Milling · Part
I

H. Zoz, H. Ren, R. Reichardt, H.U. Benz, A.
Nadkarni, G. Wagner

The High Energy (ball) Milling technique (HEM) offers an
efficient way to metal flakes. Flakes are used as metallic paints
and as electrical conductive material. This leads from decoration
purposes mostly based on Au, Cu and Au-Ag-Cu-alloys up to
paint-pigments in automotive as well as from soldering material for
micro-electronics up to printable flake-pastes for every
computer-keyboard and most of the screen-heating in automotive.
Flakes can be used in the liquid phase sintering technique (LPS) as
a suitable starting geometry for coating the to be sintered
component as well as in soft magnetic materials, where the coating,
the incapsulation of a magnetic by a nonmagnetic can be obtained by
adding nonmagnetic and ductile flakes to spherical and less ductile
magnetic powder in a correspondingly tuned milling process. The
today conventional processing route is described by a low kinetic
milling process in (drum) ball mills either in wet condition often
using alcohol or in dry condition using stearic acid or other
organic process control agent. This leads to milling times in the
range of 5 hours up to several days. By the here discussed method,
the high kinetic energy transfer in the high energy milling process
is used to deform powder particles to the flaky geometry with a
minimum of time for the single flake where a ratio of thickness and
diameter up to 1000 can be reached and a processing time of only 3 –
60 minutes is needed. A thickness far below 1µ can be reached. The
dependency of ready flake and starting particle -size and -geometry
has been investigated. A theoretical calculation model determining
the number of starting powder particles including the number of to
be expected interlayer creating a single flake in dependency of
flake size and thickness will be discussed. The deformation behavior
of the materials [Au], [Ag], [Cu], [Ti], [Al], [Ni] and [Fe] has
been investigated. The results obtained by scanning electron
microscopy will be discussed.



 

---

Improved Ag-SnO2 Electrical Contact
Material Produced by Mechanical Alloying

H. Zoz, N. Späth

Silver cadmium oxide used as a conventional material for
electrical contacts and other electrical components during a couple
of years exhibits a lot of advantageous properties like a good
thermal conductivity, a low contact resistance, a low welding force
and a high ability of arc quenching [1]. However, especially
concerning the problem of the toxicity of cadmium oxide, the
application of this material will be reduced to a minimum in the
near future and has to be replaced by a suitable material with
similar but minor harmful properties. A very promising candidate for
such an application is represented by the system silver tin oxide
[2]. Following a new processing technique [3], the basic powder
component Ag-SnO2 was produced on the powder metallurgical route by
reactive milling. The starting powders – the silver tin alloy Ag3Sn
and silver oxide (Ag2O) – were mechanically alloyed in a Simoloyer
(Zoz – horizontal rotary ball mill) in a specific concentration
ratio. During processing a chemical reaction takes place which leads
to a high dispersed phase distribution of nanoscaled SnO2-particles
in a silver matrix. Due to the applied temperature conditions and
the milling parameters a completed reaction can be observed. Being
compacted and sintered to a dense bulk material and brazed on copper
contacts the silver tin oxide should exhibit the above mentioned
properties which are currently tested by further experiments.
Results will be available in the near future.  A characterization of
the mechanically alloyed and sintered powders will be done by
optical and scanning electron microscopy (SEM) and also by X-ray
diffraction (XRD) studies.



 

---

High Energy Milling / Mechanical Alloying
/ Reactive Milling

H. Zoz, H. Ren, R. Reichardt, H.U. Benz

Zoz GmbH is an SME-company in PM-business located in
Germany with sales partners all over the world. Originally Zoz is a
ball(drum)mill-producer. These quite simple systems mostly are
supplied in Europe and go into Chemical- Ceramic-, Pharmaceutical-
and Food-, and for more than 50 % into the Hard-Metal industry. Here
the technological challenge is slightly higher as the product is
heavy and the kinetic level shall be kept. In
chemical-pharmaceutical industry, often ceramic-lined (coated) mills
are needed, e.g. for pigments of paints. For processing of
hard-phase materials, steel-mills with hard-coated or lined vessels
and partly also rubber-coatings are used. The equipment includes
feeders, vibrating screens, Agitator tanks etc. that is as al our
products completely developed, designed and produced in-house. Since
about eight years, Zoz specializes in the technology of Mechanical
Alloying (MA). This is performed by a high kinetic milling process
that, due to extremely high and / or often needed active surface of
the powder-product, shall mostly be done under complete inert-gas
condition, sometimes under vacuum. The equipment that is developed,
produced and used is the Simoloyer® and may be described as the high
kinetic horizontal-rotary-ball-mill. The major parameter here is the
maximum relative velocity of grinding media which transfers kinetic
energy into the powder. The CM-Simoloyer® can reach up to 14m/s in
dry operation mode. The equipment includes vacuum-airlock-systems,
glove-boxes, software which is all produced in-house as well. The
first industrial application of Mechanical Alloying (MA) has been
introduced in Japan in October 1997 where in this case the
processing is better to be described as High Energy Milling (HEM).
In fact it is a very successful production of copper and bronze
flakes within 3 minutes processing time in a semi-continuous mode
(see corresponding publication). Today Zoz is a leading partner for
high intensity milling processes (Mechanical Alloying, High Energy
Milling, Reactive Milling) on a laboratory and industrial scale.
Intensive work on developments on materials science, that directly
refers to applications in wear-resistance, cutting or tooling,
hydride / de-hydride, radar adsorption, shielding, paint pigments
and many others is done. The HV-Simoloyer® is of a much lower
kinetic than the CM- Simoloyer® systems. The drive-power is roughly
leveled like the since decades known attritors of many similar
brands. Indeed the HV-Simoloyer® covers corresponding applications
in the range of low- and medium-kinetic processing and can be
operated in horizontal as well as in vertical mode. Furthermore the
grinding chamber can be turned 45 degrees over the vertical
position. This can be done controlled during processing so that e.g.
by means of cyclic turning +/- 45 degrees around the vertical axis,
highly sensitive metal-flakes like platinum, silver or tantalum can
be produced much more successfully as the problematic sinking effect
of these materials during common vertical processing (dead zone due
to gravity) can be compensated. The original reason for designing
the HV-Simoloyer® has been a fully reaction on the market’s needs.
Even under the high prospective for a much more efficient and
economical production route, our customers and potential customers
are extremely reserved to introduce a new production route or a new
production principle. The change from a vertical processing system
to a horizontal one is enough variation to make one consider this as
a failure source for a long term introduced existing product. In
particular the long term-stability of pigments for automotive paint
industry as well as e.g. conductive pastes for computer-industry
cause a lot of doubts therein. With respect to this, it had been
necessary to introduce a new system that can build a bridge between
the common antiquated equipment and the modern
Simoloyer®-technology. Next to the above our main investigation
objectives today focus on the following founded projects in process:
· TPW-Project Ceramic-Simoloyer®; · Brite Euram Project Contact
Material Ag-SnO2 ; · CRAFT-Project highly dispersed (nano-scaled)
SiC in an alumina-matrix; Since the previous mentioned successfully
Cu-flakes production in Japan, we focus on the use of our high
kinetic process to explore and produce ductile metal flakes. At
present we concentrate on the production based on Pt-, Pd-, Au-,
Ag-, Cu-, Fe-, Ti-, Al- and Ni-powder for various applications. One
of the most important applications are paints (pigments) in
particular for automotive and conductive paint and pastes. With this
new method, the production of flakes is possible within minutes in
comparison to a processing time as of many hours up to several days.
A typical flake is described as a particle with a thickness < 0.2 µ
and a cross-ratio of about 200 which refers to a diameter of 20 – 30
µ. As a consequence mainly from the flakes-production, at present
Zoz builds up the first Atomizer (ZAT100) which is suitable for gas-
as well as UHF-atomization based on melt out of the crucible as well
as droplet-melting with a vacuum-tube-manipulator. On the contrary
Zoz builds up one of the worldwide largest gas-atomizing systems
(ZAT5000) with a free distance between nozzle and cone of
approximately 5 meters where the diameter of the chamber is about 1
meter. The capability of this complete system including
cyclone-separation-, weight load-, heat-exchanging- and
dust-separation-unit is about 3 tons of powder per charge (cycle).
Early 1998 Zoz started a small-scale powder production using the
in-house laboratory. For the completion of external jobs as well as
for the work on research projects, several Simoloyer® (CM01, CM08
and CM20) in various types (e.g. chambers with heating system) with
full staff equipment like air-locks, sample-units up to the
glove-box are under operation. The production quantity of various
and most frequently very special materials is found in the range up
to 100 kg. Furthermore a Drummill (Comb03, laboratory scale, 30
liters) is used with various chambers. Up to now this has mostly
been used for the processing of feedstock-materials for MIM. The
Software-department of Zoz GmbH develops Multimedia-Software for
system-operation, system-control and process-control. By means of
the synthesis of decades of knowledge in mechanical engineering and
modern software technology, advanced products highly oriented at the
practical needs are created here, for the in-house needs
(Simoloyer®, Maltoz®) as well as for external customers. Next to
precision and high performance, the intuitive user guiding is a
remarkable feature of our software and is therefore easy and quickly
to be learned. Furthermore Zoz supplies advanced data-base-software
for process-optimization.



 

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Simoloyer CM100s · semi-continuously
Mechanical Alloying in a production scale using Cycle Operation · Part
II

H. Zoz, D. Ernst, R. Reichardt, T. Mizutani,
M. Nishida, H.Okouchi

The production of large quantities of powders for
industrial application e.g. in paints or soldering materials is an
aim followed by Fukuda Metal Foil and Powder Co. Ltd. in Japan. For
these applications, Cu- and Ag-particles with a special geometry
(flakes) are needed. Based on milling experiments resolved by the
Simoloyer CM01-1/2 l with a grinding unit capacity of 0.5 l for
laboratory purpose, a new grinding device has been developed using
the same principle. This Simoloyer CM100s1, suitable for a
semi-continuously production of mechanically alloyed and
mechanically particle deformed powders [2-5], has been designed and
already been described in part I of this work [9]. Part II focusses
on testing for and on industrial application of the processing and
the equipment as well as on principles regarding productivity and
costs. A new application of the Maltoz-control-software for the
determination of the energy consumption (energy balance) will be
discussed. The batch operation procedure has already been done in
Germany in September 1997. The efficiency of the system was even
much higher than expected. The well-known problems when processing
CMB-materials (ductility etc.) [1, 6, 7] were solved by using the
Cycle Operation procedure controlled by the Maltoz-software [8]. A
production capability of 600 kg of ready product per day with the
testing plant has been achieved. The testing regarding the
semi-continuous operation will be done in Kyoto in November 1997 and
consequently these data will be available for the current paper. If,
what is expected, the semi-continuously procedure and the use of the
corresponding equipment will be successful and the main processing
parameters can be kept, the expected continuous capability is
calculated to be about 4 tons of powder per day. The already proved
application in the batch process is a revolutionary step for Fukuda,
for the process and for mechanical alloying. Depending on the coming
work, it will be even more.



 

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Simoloyer CM100s · semi-continuously
Mechanical Alloying in a production scale using Cycle Operation · Part I

H. Zoz, D. Ernst, T. Mizutani, H. Okouchi

Die Produktion großer Pulvermengen für industrielle
Anwendungen z.B. für Farben und Lotwerkstoffe ist ein Ziel, welches
von der Fukuda Metal Foil and Powder Co. Ltd. in Japan verfolgt
wird. Für diese Anwendungen sind bestimmte Partikelgeometrien
erforderlich, wie z. B. ein spezielles
Durchmesser/Dicken-Verhältnis. Da der frühere Produktionsweg für die
Partikelformen bei Fukuda sich als sehr zeit- und kostenintensiv
erwiesen hat, wurden in einem Simoloyer CM01-½ l (horizontale
Zoz-Rotorkugelmühle) mit einem Mahlraumvolumen von ½ Liter
Mahlexperimente mit dem Ziel durchgeführt, Silber-Mikroflakes unter
dem Aspekt einer kürzeren Prozeßdauer und höherer Effizienz zu
erhalten. Die Versuchsergebnisse zeigen auf, daß dieser Weg sich als
äußerst geeignet erweist, das gewünschte Produkt wirtschaftlich und
effektiv herzustellen. Aufbauend auf dem gleichen Funktionsprinzip
ist es jetzt möglich, mittels des Produktions-Simoloyers CM100s
(Mahlraumvolumen 100 Liter) einen industriellen Produktionsmaßstab
zu erreichen. Die derzeitige Arbeit konzentriert sich auf die
Entwicklung einer völlig neuen Mahleinheit des Simoloyers CM100 mit
dem Ziel eines semi-kontinuierlichen Produktionsprozesses für
mechanisch legierte und mechanisch deformierte Pulver unter
Verwendung von Cycle Operation, welches sich insbesondere für
duktile Werkstoffe mit kritischem Mahlverhalten hervorragend eignet.



 

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Mechanical Alloying of Fe-Based Solid
Lubricant Composite Powders

D. Ernst, H. Weiss,
R. Reichardt,
H. Zoz

Mechanical alloying using cycle operation
· A new  way to synthesize CMB-materials ·

H. Zoz, D. Ernst

The production of large quantities of contamination free
mechanically alloyed powders has proven to be major challenge.
Feasibility of such a goal can be carried out, at laboratory level,
by any milling device like the very common planetary ball mill. In
this case however, the possibility of a subsequent scaling up for
larger production is hindered by the intrinsic limits of a planetary
ball mill design. On the contrary the Simoloyer (Zoz – horizontal
rotary ball mill) can be experimented at laboratory level using
small volume chamber-units (0.25, 0.5, and 2 l) and, for industrial
production, using the large volume units (up to 400 l) based on the
same conceptual design. A lot of the mechanically alloyed advanced
materials show a critical milling behaviour due to their ductility.
To be able to process these kind of powders nevertheless, milling
agents or / and deep temperature milling have been applied in the
past. Today these difficulties and limits are solved by the cycle
operation procedure using the so called Operation Cycle and
Discharging Cycle for the processing. The present paper will focus
on the results of several experiments on titanium, nickel, silver
and aluminum based Materials. This is investigated by chemical
analysis, by scanning electron microscopy and X-ray diffraction. A
proved powder yield over 80 % and a homogeneous and reproduceable
product allows to consider an industrial production. From the
economical point of view, this should finally be a continuous
process. The first, semi-continuously working Simoloyer (CM100s)
will be discussed.



 

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Performance of
the Simoloyer

H. Zoz

The Mechanical Alloying
(MA) technique can be used to synthesize alloy powders with interesting
properties. The technique, developed some 20 years ago, [1] can be
described as a repeated deformation, fracture, and welding of powder
particles by highly energetic ball collisions. [2] MA is important for
creating materials with controlled microstructures and enables us to
answer the demand for the high-performance materials of modern
technologies. The various materials that can be prepared by MA are
summarized in table 1.

Henning Zoz; Roland Reichardt; Ji-Soon Kim

Trommelmühlen werden sowohl im Labormaßstab
als auch in der industriellen Anwendung hauptsächlich zur Zerkleinerung
eines Aufgabeproduktes eingesetzt. Die verschiedenen Trommelgrößen und
–geometrien erfordern unterschiedliche Einstellungen der Drehzahlen und
Füllgrade. Die Kollisionen und Reibungen des Mahlkugelpaketes in der
Trommel bestimmen maßgeblich das Endprodukt.
Diese Veröffentlichung erklärt die Kinematik innerhalb der Trommel und
leitet die Flugbahnen und Auftreffwinkel der Mahlkugeln während des
Betriebs einer Trommelmühle her. Der Anwender kann mit Hilfe der
speziell für Trommelmühlen entwickelten Diagramme die Drehzahl der
Trommel so vorgeben, dass sich das gewünschte Flugverhalten einstellt.
Es werden verschiedene Trommeltypen (mit und ohne Hubbalken) erläutert,
sowie deren Einfluss auf das Mahlverhalten bzw. die
Rundlaufeigenschaften. Die hergeleiteten Formeln werden anschaulich
durch Fotos belegt und für den Endanwender verständlich aufbereitet
dargestellt.

Trommelmühlen: Allgemeine Betrachtungen

H. Zoz

Trommelmühlen werden zur Aufbereitung unterschiedlichster Produkte
eingesetzt. Es handelt sich hier um einen diskontinuierlichen Prozess,
bei dem durch die Auswahl unterschiedlicher Parameter auch
unterschiedliche Prozessvarianten möglich sind.