Zeitschrift Kunststofftechnik Flock, Kutschmann et al. US ...

Flock, Kutschmann et al. US-Welding of Hybrid Metal-Plastic Components

© Carl Hanser Verlag Zeitschrift Kunststofftechnik / Journal of Plastics Technology 7 (2011) 5

Submitted: 31.03.2011 Accepted: 12.07.2011

Dipl.-Ing. Dustin Flock, Prof. Dr.-Ing. Edmund Haberstroh, Chair of Rubber Technology (LFK), RWTH Aachen University,

Prof. Dr.-Ing. Kirsten Bobzin, Dipl.-Ing. Thomas Schläfer, Dipl.-Ing. Thomas Warda, Dipl.-Ing. Pia Kutschmann, Surface Engineering Institute (IOT), RWTH Aachen University

Ultrasonic welding of hybrid metal-plastic components with flame spraying of adhesion layer Hybrid components of different materials increasingly gain in importance, especially in automotive engineering (reduction of fuel consumption, meeting of environmental protection targets). Here hybrid components made of plastic and metal materials are used. The combination of the positive features of both material groups results in a component providing high stiffness at a low weight. A joining process used for its implementation is ultrasonic welding. Subject of this research paper is the identification of process control factors influencing the welding seam quality. A pretreatment method is used, where a flame-sprayed bond coat is applied onto the metal substrate. This work is part of the Cluster of Excellence “Integrative Production Technology for High-Wage Countries" of RWTH Aachen University.

Ultraschallschweißen von Metall-Kunststoff-Hybridbauteilen mit flammgespritzten Haftvermittlerschichten Hybride Komponenten aus unterschiedlichen Werkstoffen gewinnen immer mehr an Bedeutung, insbesondere in der Automobilindustrie (Reduktion des Kraftstoffverbrauchs, Einhaltung von Umwelt-schutzauflagen). Hierbei werden häufig Metall-Kunststoff-Komponenten verwendet. Die Kombination der positiven Eigenschaften führt zu Komponenten mit einer hohen Steifigkeit bei niedrigem Gewicht. Einen möglichen Fügeprozess stellt das Ultraschallschweißen dar. Inhalt der hier vorliegenden Arbeit ist die Identifizierung der Einflussfaktoren auf die Schweißnahtqualität. Als Vorbehandlungsmethode wird die Applikation flammgespritzter Haftvermittlerschichten genutzt. Die Arbeit ist Teil der Exzellenzclusters „Integrative Produktionstechnik für Hochlohnländer" der RWTH Aachen University.

Zeitschrift Kunststofftechnik Journal of Plastics Technology Archivierte, peer-rezensierte Internetzeitschrift des Wissenschaftlichen Arbeitskreises Kunststofftechnik (WAK) Archived, peer-reviewed online Journal of the Scientific Alliance of Polymer Technology www.kunststofftech.com; www.plasticseng.com

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Journal of Plastics Technology 7 (2011) 5 161

Ultrasonic welding of hybrid metal-plastic components with flame spraying of adhesion layer

D. Flock, E. Haberstroh, K. Bobzin, T. Schläfer, T. Warda, P. Kutschmann

Plastics play an important role in lightweight construction. The low weight and the high freedom of design of plastics are advantageous. Compared to plastics, metals provide higher rigidity. Suitable joining methods are required to combine both advantages into a hybrid component.

1 INTRODUCTION

Currently adhesive bonding (glueing) processes are often used to realise a bond between plastics and metals. Among others, disadvantages of these adhesive bonding processes are the limited temperature stability of the bond as well as the maximum achievable strength, which significantly depends on the adhesive surface. Other possibilities to combine plastics with metals are mechanical bonds. In this case, bolting connections as well as inserts are feasible [1].

Hybrid metal-plastic compounds cannot be generated using welding in the conventional sense. The melting temperature ranges of both materials are so far apart that plastic is already thermally degraded before the metal component is molten. However, based on the surface structures of appropriately prepared metal surfaces, the plastic can possibly develop a form closure. The surface-topographical consistency allows micro clamping of the plastic. The molten plastic flows into the undercuts of the metal surfaces and solidifies.

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2 PROCESS DESCRIPTION

Ultrasonic welding of plastics is a series welding process with extremely short welding times of 0.1 to 1 s. Physical restrictions limit the welding seam length to 150 mm to 300 mm (with increasing sonotrode size problems as far as uniform energy input into the component and increasing vibrating mass can occur). In other words, ultrasonic welding is limited to components of small to medium sizes [1].

2.1 Process Sequence

The heat required for melting of the plastic part during ultrasonic welding is generated via the dissipation of induced mechanical vibration energy. The plastic melts at the joint and the components are joined under pressure [1, 2].

The welding process sequence can be divided into four different process phases [3]:

Phase 1: Partial melting of the energy director

Phase 2: Unsteady melt formation

Phase 3: Quasi-stationary melting phase

Phase 4: Holding phase / cool-down phase.

2.2 Challenges When Joining Hybrid Components

In the following the challenges of joining metals with plastics by ultrasonic welding are described. In contrast to welding of two plastic parts, in phase 2 (“unsteady melt formation”) a coupling between upper and lower part via the melt layer does not occur. Unsteady melting of the energy director can be observed, however, no constant melting temperature or melt layer thickness is generated, which usually happens in plastic ultrasonic welding. The cold metal surface causes direct solidification (also called freezing) of the plastic in the border regions of the joining zone, figure 1. Constant rheological and thermal conditions (phase 3) cannot be formed. Depending on the metal substrate used, its thermal conductivity is by a factor of 100 to 1,000 higher than the conduc-tivity of plastics. The thermal energy is directly led off and is not available for the plastic. The plastic component solidifies on the plastic-metal contact surface without flowing into the metal structures. An extension of the welding time results only in softening of the entire plastic component. The sonotrode, which should generate the welding pressure, presses into the plastic component surface without forming a connection with the metal.

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Figure 1: Joining process when joining plastics on metals

Heating up of the metal components can provide a better adhesion [4], but it is limited as far as the metal temperature is concerned. With temperatures near to the melting point of the plastics used, typical mechanism of heat conduction welding occur and the ultrasonic effects are reduced. A promising approach for using ultrasonic welding is the application of a bond coat onto the metallic surface, e.g. by plastic flame spraying.

2.3 Coating Process Using Plastic Flame Spraying

Plastic flame spraying is a thermal spraying method, which can be used for the application of a plastic coating onto a metal component to be joined. During this process the metal surface remains unmelted [5]. The coating is built by impacting of the sprayed particles, which deform and solidify in pancake-like shapes on the substrate surface. During plastic flame spraying a plastic powder feedstock is heated in a fuel-oxygen flame (mostly an acetylene-oxygen mixture), figure 2. Special spray nozzles are used, as plastic powder with typical particle size distributions between 50 and 250 µm [6] would degrade in the hot flame. The spray nozzle design ensures that the axially injected powder is shielded against the outer flame using a cooling gas ring. Melting of the powder is realised by indirect heat transfer [7]. Compressed air or an inert gas such as nitrogen or argon is used as cooling medium. This also supports powder feeding as well as its acceleration towards the substrate. Preheating the substrate in a temperature range from 60 to 250 °C - depending on the substrate and plastic materials - is required [6] for plastic flame-spraying material. The energy stored in the workpiece will thus cause melting of the sprayed-on plastic particles. Therefore, the component temperature is critical during thermal spraying [8]. Adhesion of the coating on the substrate mainly results from mechanical clamping, which in addition requires a roughened surface.

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Figure 2: Plastic flame spraying principle

1) Acetylene-oxygen, 2) Feedstock material, 3) Spray nozzle, 4) Shielding gas (cooling gas ring), 5) Acetylene-oxygen flame, 6) Partly molten plastic, 7) Workpiece [9]

In the early nineties Grewell conducted first experiments using flame-sprayed bond coats for metal and plastic joining [10]. Polysulfone and polyetherether-ketone (PEEK) thermoplastics were applied to a metal substrate using flame spraying and then successfully joined with the respective polymers using vibration welding. Aluminum and stainless steel were used as metals. In the tensile shear test, the produced overlap joint compounds mainly showed cohesive failures with shear adhesion strengths up to 26 MPa.

3 EXPERIMENTS

Joining of polyamide 66 (PA66, length: 70 mm, width: 20 mm, thickness: 2 mm, Schulamid 66 MV3 by A. Schulman GmbH, Kerpen) and austenitic steel 1.4301 (X5CrNi18-10, same sample size as PA66) using ultrasonic sound (US) is being investigated. The steel substrate is sprayed with a bond coat using plastic flame spraying. The polyamide 11 (PA11) bond coat should enable joining of this material combination. The joining experiments are done with an overlap joint (one of the standard joining geometries), which is evaluated using cross-sections and tensile shear tests. The PA66 substrate is stored at normal surround conditions (23 °C, 50 %), without special pre-drying.

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3.1 Plastic Flame Spraying

The bond coat is applied onto the steel substrate using plastic flame spraying. Partially crystalline polyamide PA11 (GTV plastic 35.900.1, GTV GmbH, Luckenbach, Germany) with a particle size distribution of 45 -125 µm, with a melting point of approx. 184 - 186 °C, is used as feedstock material [11]. The Uni Spray Jet (GTV GmbH, Luckenbach, Germany) spray gun is utilised for bond coat application (neutral acetylene-oxygen flame with 0.5 bar acetylene pressure and 2.5 bar oxygen pressure). The pressure of the compressed air (shielding and powder carrier gas) amounts to 2 bar. The spraying distance is 200 mm. For all specimens, the coating structure is generated by traversing twice across the specimens at a surface velocity of 0.35 m/s.

The steel is prepared by blasting with aluminum oxide EKF 16. Just before coating, the substrate surface is heated up using the fuel-oxygen flame, in order to ensure complete melting of the sprayed particles (no freezing effects, cp. chapter 2.2) and clamping with the substrate. The influence of the preheating temperature on coating formation and joining connection is investigated by variation of the substrate temperature. The preheating temperature is controlled by the flame holding time on the substrate. The mean temperature over the substrate cross section area is determined using a thermal imaging camera. In the following table 1 the mean substrate temperatures just before the coating process are listed.

Parameter variation

Holding time [s] 1 6 8 10

Mean temperature [°C] 80 145 178 210

Standard deviation - 7.6 9.2 9.3

Table 1: Substrate temperature variation prior to spraying the bond coat

The flame-sprayed coatings are characterised by visual inspection in order to assess the melting degree of the plastic powder. In addition, cross sections are prepared, which will be used for porosity and coating thickness measurements with a digital image analysis software.

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3.2 Ultrasonic (US) Welding

The used US welding system from Branson Company, Dietzenbach, is a system especially adapted to welding of small plastic components. The generator (type identification PGB 470 A) provides a working frequency of f = 40 kHz and a maximum power of P = 700 W. The amplitude can be continuously adjusted using a handheld throttle. It must be noted that the relative fraction of the maximum amplitude can be adjusted via the throttle. It is not possible to adjust an explicit amplitude value. For this reason, the amplitudes are provided in percentage for the test parameter presentation in table 2. The aluminum sonotrode used for welding is matched to the system and the application case. The booster made of titanium has a transmission ratio of 1:1.5.

Welding velocity [mm/s]

0,1 0,2 0,5

Amplitude [%]

50 75 100

Joining path [mm]

0,5 1

Table 2: Test parameters and their variations

In order to meet the accurate positioning requirements, the welding press is equipped with a servo-electrical drive of Micos GmbH, Eschbach, with a traversing range of 110 mm and a repetitious accuracy of 2.5 µm.

The joining device, especially designed for this welding task, is responsible for holding both welding parts and positioning them below the sonotrode. The joining device is equipped with longitudinal holes for axial mobility below the sonotrode. A defined overlap length of the parts to be welded must be ensured and their positions must be fixed relative to each other for reproducible welding results. The metal sample located under the plastic sample during welding, is axially fixed via a recess. The position of the plastic specimen is ensured by the side walls on the one hand and the joining pressure applied by the sonotrode on the other hand, figure 3.

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sonotrode

metal specimen plastic specimen

Figure 3: Welding device

The bonding strength of the compound, which is determined using tensile shear tests, as well as light-microscopy images of cross sections are observed for the characterisation of the joining connection. ZnSe vapour deposition is applied to the cross sections for better contrasting of the PA66 specimen and the PA11 bond coat.

The tensile testing machine Zwick Z010 from the Zwick/Roell GmbH, Ulm, is used for mechanical testing of the welded samples. The specimens are clamped in separately adjustable screwed sample holders and subjected to the tensile shear test. The tensile shear test is based on the conditions of the test standard DIN EN 527/1-4. A tensile test velocity of 50 mm/min is adjusted.

4 RESULTS

4.1 Ultrasonic Welding Without Bond Coat

It is not possible to realise an adhesive bond of hybrid metal-plastic components without pretreatment of the metal substrate. In our experiments using blasted and preheated metal substrates, it was only possible to achieve adhesion via form closure with a structured metal surface at a surface temperature of approx. 180 °C, close to the melting temperature of the plastics used, figure 4. In addition to the already induced US energy, this process requires high thermal energy and is characterised by very long cycle times. The breaking force, achieved in this way amounts to 850 N for the combination of laser-structured steel with polyamide. This value can be increased to 950 N by plasma pretreatment of the PA material [4]. The good adhesion of thermal sprayed coatings suggests that these coatings could possibly result in higher breaking forces after welding.

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steel

plastic

undercuts

Fig. 4: Cross section (incident light image) of a joined hybrid compound

Due to the bond coat on the metal substrate, hybrid parts with higher strength can be produced in short cycle times. However, when inspecting the joining parts it could be observed that the plastic samples showed damage at the contact surface with the sonotrode. Figure 5 shows how the plastic component is molten at the contact region and the sonotrode penetrated the plastic specimen. The effect is related to the processes in the joining zone during welding and will be explained in the following.

Fig. 5: Sonotrode marking on the plastic surface

The highest sonic energy dissipation into the energy director takes place during welding. The generated melt is in immediate contact with the colder environ-ment, cools down and avoids further spreading in the joining zone. The melting of the energy director increases the contact surface between plastic component and metal substrate and thus, lowers the compression stress in the boundary layer. If this stress falls below the stress in the contact surface towards the sonotrode, the plastic on the surface starts yielding and the sonotrode

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penetrates into the plastic. This effect is strongly related to the welding time, which is varied between 1 to 10 s in the welding experiments.

4.2 Application of Flame-Sprayed Bond Coats

Substrate preheating has the largest influence on melting behaviour and melting of impacting plastic particles during plastic flame spraying. Figure 6 shows PA11 coatings on 1.4301 substrates with different preheating temperatures. It can be observed that with increasing preheating temperature the coating surface exhibits less roughness. This indicates that melting of the PA11 particles is improved at higher temperatures. However, at 210 °C the coating surface starts to turn yellow. Because the preheating temperature is above the melting temperature of the PA11 powder, this may indicate the start of plastic degradation. Fourier transformation infrared spectroscopy (FTIR) of the original powder, of a coating with appropriate parameters and a further coating with inappropriate parameters (substrate temperature above 178 °C), shows that powder oxidation takes place during the spraying process. The increase in carbonyl groups (CO) at high preheating temperatures (> 178 °C) is significantly higher than at lower substrate preheating temperatures.

Figure 6: PA11 bond coats

The typical coating structure of a plastic flame-sprayed coating with previous substrate preheating is shown in the cross section in Figure 7. Adhesion of the coating on the blasted substrate, which was preheated to 178 °C before the coating process, is obviously good. Molten plastic particles could penetrate into the roughness topography and undercuts of the substrate surface, solidify there and clamp mechanically. The homogeneity in the coating structure indicates an appropriate melting of the sprayed particles. Evaporating of humidity within the plastic powder during spraying is responsible for the recognisable pores. The cross sections of the coating structure for preheating to 145 °C and 210 °C correspond to figure 7.

145°C 178°C 210°C

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PA11 bonding agent

stainless steel 1.4301 200 μm

closed pores

Figure 7: Cross section image of the PA11 bond coat on steel 1.4301 preheated to 178 °C

0

100

200

300

400

500

600

80°C 145°C 178°C 210°C

substrate preheating

coat

ing

thic

knes

s [μ

m]

0

2

4

6

8

10

12

poro

sity

[%]

coating thickness porosity

Figure 8: Coating layer thickness and porosity of the bond coat versus substrate preheating

The results of coating thickness and porosity measurements are summarised in figure 8. Although the number of passes has been kept constant for all preheating temperatures, the layer thicknesses show significant differences. The coating thickness for specimens preheated to 145 °C and 178 °C is approx. 510 µm. At a lower substrate temperature of approx. 80 °C, a significantly lower coating thickness of 340 µm is achieved, caused by worse plastic particle melting. Especially larger spray particles are not molten completely and bounce off the substrate. In comparison with the specimen being preheated to 145 °C (figure 6), the surface structure is rougher. The lower coating thickness at a preheating temperature of 210 °C is caused by the selected lower powder feed

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rate and the associated better melting of the spray particles. The influence of substrate preheating on coating porosity cannot be clearly determined. Nevertheless, at a preheating temperature of 178 °C, the porosity is slightly higher than the porosity at any other temperatures.

4.3 Ultrasonic Welding With Flame-Sprayed Plastic Coating

Figure 9 presents the US welding process and the typical joining zone of a plastic-plastic bond. The polyamide phases of the PA66 specimen and the PA11 bond coat show good bonding. During the joining process the thickness of the bond coat is reduced. The area of the coating near to the surface is molten and pushed out of the joining zone by the pressure. The interface between bond coat and steel substrate is not influenced by the joining process.

Fig. 9: Joining zone of a PA66-PA11-steel 1.4301 compound with substrate preheating to 145 °C prior to the coating process

4.4 Tensile Tests

Figure 10 illustrates the failure stresses achieved for the joints of PA11-coated steel with PA66 using US welding. A correlation with the coating thickness applied with flame spraying can be observed (cp. figure 8). The compounds, which were joined ultrasonically, reach higher failure stresses than compounds joined by glueing. The stresses were calculated using the resulting overlap length of the joints (cp. figure 12). As can be seen in figure 11, most of the samples failed within the PA66 substrate and not within the welding seam. It is evident that these specimens fractured without visible elongation and directly

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below the sonotrode marking. A possible explanation is the influence of the stress concentration caused by the sonotrode marking in combination with the combined shear-tensile stress. Taking these effects into account and calculating the tensile stresses with the residual cross section of the PA66, failure stresses of 20-57 MPa can be reached. A comparison with material characteristics of PA66 shows that the maximum stresses generated are in the range of the yield stress of PA66 (air-humid, table 3). In case of unwelded plastic specimens (here pure tensile stresses are generated), fractures only occurred after very large elongations.

Material Yield stress (dry) [MPa]

Yield stress (air-humid)

[MPa]

Max. water absorption at 23 °C in air (50% RH)

[%] PA66 75-100 50-70 2.8

Table 3: Characteristics of PA66 [12]

Figure 10: Failure stresses depending on the substrate preheating temperature in comparison to a glued 1.4301-PA66-compound

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failure zone

pressure marking of sonotrode

welded PA66 specimen

unwelded PA66 specimen

Fig. 11: Welded and unwelded PA66 specimens after the tensile test

5 DISCUSSION

The approach for joining of 1.4301-PA66-compounds followed in this work is based on the application of a thermally sprayed PA11 bond coat. The results show that maximum bond strength can be achieved which lie in the region of the plastic strength. Furthermore these results suggest a correlation between the process temperature of the coating and the strength of the welded components. The following discussion focuses the correlation between these two parameters. So the influence of the coating temperature on the bond strength will be discussed.

First, it can be noticed that the plastic coating structure varies with different coating temperatures. Porosity has its maximum at a coating temperature of 178 °C. Compared to plastics, air exhibits ten times lower thermal conductivity. For this reason, the coating structure has a considerable influence on the heat influence zone formation at the joint. Due to the insulating character of air porous coatings counteract the dissipation of introduced heat from the joining zone and they also counteract melt formation. Therefore the proliferation of the heat influence zone vertically to the joining path is inhibited. Due to the prevented heat dissipation from the joining zone, the welding time is shortened, while the breaking forces reach a maximum.

For some samples in figure 10 distinctive variations in the breaking forces occur, such as, for example at 210 °C. It could be explained with a possible

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material degradation at this temperature (cp. chapter 4.2). Another possible reason for the variation could be the difference in the polymer coating thickness, which varies for the different specimens, figure 8. When comparing with figure 10, it can be observed that both diagrams show similar qualitative characteristics. This may suggest a possible correlation between these parameters. The polymer coating thickness has a twofold effect on the welding result. When assuming a constant traverse path of the welding press, different coating thicknesses result in different joining pressures, which are reflected in the strength values as described above. With increasing polymer coating thickness, the plastic specimen is insulated from the metal substrate with increasing effectiveness. As a result, less heat is dissipated via the substrate from the joining zone. Thus, it is available for plasticisation of the plastic material. In figure 12 the layer thickness influence can be clearly recognized. In case of the centre specimen with the thickest polymer coating, the sideways melt expulsion and thus, the bonding surface is the largest. The lower specimen with the thinnest layer thickness shows the smallest expulsion and thus, the smallest bonding surface of the three samples.

Fig. 12: Cross section views of the joining zones

Another factor influencing the bond strength is the specimen clamping mechanism in the tensile test system. Due to the geometry of the lap joint (one of the standard geometries for testing), the seam is not only subjected to shear, but an additional moment is induced, which cannot be eliminated completely. As a result the moment will vary with the position of the clamping jaws of the tensile test system. This may falsify the effective strength. If the mentioned errors occur in combination, large deviations may occur within the same measurement series.

T=145 ° C

T=178 ° C

T=210 ° C

pressure marking of sonotrode

squeeze flow

cavities

2 mm

2 mm

2 mm

of sonotrode

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6 SUMMARY AND OUTLOOK

The combination of coating metals with thermal flame spraying and ultrasonic welding enables the production of hybrid components. Welding experiments have shown that it is simply not possible to bond plastics with metals to hybrid components using ultrasonic welding without a bond coat. By means of a plastic coating, assuming optimum parameters, bond strengths similar to the basic strength of the plastic can be achieved. The breaking forces achieved mainly depend on the control of the coating parameters. The coating temperature has a large influence on the coating structure, which in turn impacts achievable strength values. Too high substrate temperatures result in thermal damage of the applied plastic coating. Too low temperatures result in insufficient coating adhesion on the metal.

Future work will focus on the determination of a process window in order to prevent damage of the plastic specimens caused by sonotrode penetration. Furthermore, the exact correlations between coating temperature, coating thickness and the resulting component strength must be determined. In addition to the welding parameters, the influence of the material selection (substrate material and also coating material) and the pre-drying conditions on the bond strength must be investigated.

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Literature

[1] Ehrenstein, G.W. (Hrsg.).

Handbuch Kunststoff-Verbindungstechnik

Carl Hanser Verlag, München, 2004

[2] Potente, H. Fügen von Kunststoffen

Carl Hanser Verlag, München, 2004

[3] N.N.. DVS 2216 Teil 1, Ultraschallschweißen von Kunststoffserienteilen

DVS-Verlag GmbH, Düsseldorf, 2007

[4] Michaeli, W.; Hoffmann, W.-M.

Hybrid Joints,

Kunststoffe International, Carl Hanser Verlag, München, 2009

[5] N.N. DIN EN 657, Thermisches Spritzen – Begriffe,. Einleitung, 2005

[6] Winkler, R.; Büttmann, F.; Hartmann, S.; Jerz, A.

Thermal Spraying of Polymers: Spraying Processes, Materials and New Trends

Thermal Spray 2003: Advancing the Science & Applying the Technology, (Ed.) C. Moreau an B. Marple, ASM International, 2003, S. 1635-1638

[7] Gourlaouen, V.; Dominguez, R.; Monerie-Moulin, F.; Mendelsohn, M.

Plastic Coating Properties obtained by Flame Spraying Process and their Application

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[11] N.N. Informationsblatt, GTV Polyamid 11 (PA)

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Keywords: Ultrasonic welding, flame spraying, hybrid plastic metal components

Stichworte: Ultraschallfügen, Thermisches Spritzen, hybride Kunststoff Metall Verbindungen

Autor/author: Dipl.-Ing. Dustin Flock (Author) Prof. Dr.-Ing. E. Haberstroh (Professor) RWTH-Aachen University Chair of Rubber Technology RWTH-Aachen University Eilfschornsteinstr. 18 52056 Aachen Germany

E-Mail-Adresse: [email protected] Webseite: www.lfk.rwth-aachen.de Tel.: +49(0)241/80-93849 Fax: +49(0)241/80-92447

Autor/author: Dipl.-Ing. Pia Kutschmann (Author) Dipl.-Ing. Thomas Warda Dipl.-Ing. Thomas Schläfer Prof. Dr.-Ing. Kirsten Bobzin (Professor) RWTH-Aachen University Surface Engineering Institute RWTH-Aachen University Kackertstr. 15 52072 Aachen Germany

E-Mail-Adresse: [email protected] Webseite: www.iot.rwth-aachen.de Tel.: +49(0)241/80-95329 Fax: +49(0)241/80-92264

Herausgeber/Editor: Europa/Europe Prof. Dr.-Ing. Dr. h.c. Gottfried W. Ehrenstein, verantwortlich Lehrstuhl für Kunststofftechnik Universität Erlangen-Nürnberg Am Weichselgarten 9 91058 Erlangen Deutschland Phone: +49/(0)9131/85 - 29703 Fax.: +49/(0)9131/85 - 29709 E-Mail-Adresse: [email protected]

Amerika/The Americas Prof. Prof. h.c Dr. Tim A. Osswald, responsible Polymer Engineering Center, Director University of Wisconsin-Madison 1513 University Avenue Madison, WI 53706 USA Phone: +1/608 263 9538 Fax.: +1/608 265 2316 E-Mail-Adresse: [email protected]

Verlag/Publisher: Carl-Hanser-Verlag Jürgen Harth Ltg. Online-Services & E-Commerce, Fachbuchanzeigen und Elektronische Lizenzen Kolbergerstrasse 22 81679 Muenchen Tel.: 089/99 830 - 300 Fax: 089/99 830 - 156 E-mail-Adresse: [email protected]

Beirat/Editorial Board: Professoren des Wissenschaftlichen Arbeitskreises Kunststofftechnik/ Professors of the Scientific Alliance of Polymer Technology

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