Papers

ICMCTF2002 Session B6-1: Laser Assisted Deposition and Surface Processing

Tuesday, April 23, 2002 1:30 PM in Room Royal Palm Salon 1-3

Tuesday Afternoon

Start	Invited?	Item
1:30 PM		B6-1-1 Laser Forward Transfer of Sensor and Battery Materials for Novel Device Applications A. Piqué, C.B. Arnold, K.E. Swider-Lyons, R. Wartena, B. Pratap, R.C.Y. Auyeung, D.W. Weir, R.A. McGill, D.B. Chrisey (US Naval Research Laboratory) Contemporary and next generation commercial and defense related platforms offer countless applications for thin film coatings made from novel materials. The implementation of these new materials is expected to improve both device capabilities and performa nce, while the range of possible applications for these coatings include the areas of microelectronics, miniature sensors and micro-power sources. In many cases, the compositional and structural complexity, and the anisotropy of the materials properties p reclude processing by conventional physical or chemical vapor deposition methods. Furthermore, the temperature requirements of these materials limits their proccesability by traditional thin film techniques . The Naval Research Laboratory has developed an advanced laser-based forward transfer processing technology for direct-writing of novel structures and devices. Using this laser forward transfer technique, we have demonstrated the ability to rapidly prototype temperature, pressure and chemical sensor d evices as well as miniature power sources on almost any type of substrate. Various types of miniature sensor and microbattery designs, including sensor arrays have been fabricated using metals, polymers and composites under ambient conditions. The lase r forward transfer process is computer controlled which allows the design of the device to be easily modified and adapted to any specific application. Furthermore, the same process enables the fabrication of complete sensor or power source systems by inco rp orating the passive electronic components required for sensor readout or power management. Examples of various types of miniature sensors and microbatteries, together with current and future applications where these types of devices might play a role will be provided. This work was supported by the Office of Naval Research. p.
2:10 PM		B6-1-3 Pulsed Laser Deposition: a New Technology for Coating of Sheet Materials and Three Dimensional Industrial Components W. Waldhauser (JOANNEUM RESEARCH Forschungsgesellschaft mbH, Austria); R. Ebner, J.M. Lackner (Werkstoff-Kompetenzzentrum-Leoben Forschungsgesellschaft m.b.H., Austria); W. Lenz (JOANNEUM RESEARCH Forschungsgesellschaft mbH, Austria) Over the past decade Pulsed Laser Deposition (PLD) has become a well established laboratory method to deposit a variety of thin films with complex chemical compositions for magnetic, electric or semiconductor applications. In literature the deposition of more than 300 different materials (compounds) by means of PLD has been reported. However, PLD has not become yet a standard industrial technology for coating of three dimensional components. One of the main reasons which restricts a spreading of the PLD technology is that the equipment available on the market is very limited. It is expected that more than 90% of the existing laser deposition systems are "home-built". The paper presents a new multi-source PLD evaporation system and the resulting possibilities for coating of sheet materials and three-dimensional parts. The superposition of material fluxes from several evaporation points ensures a very uniform distribution of coating thickness. A high mean laser power guarantees deposition rates competitive to other physical vapour deposition techniques. Because of the specific process conditions thin films with a good adhesion and favourable structure can be produced at low temperatures (room temperature up to 100°C). The coatings exhibit very fine crystalline or amorphous structures depending on the materials used and the deposition parameters. PLD coatings are potentially applicable for wear protection of high precision components or of parts made of temperature sensitive materials. In addition PLD is also suitable for deposition of thin films onto plastic and ceramic materials. Various examples will be reported.
2:30 PM		B6-1-4 Magnetron Sputter Pulsed Laser Deposition: Technique and Process Control Developments J.G. Jones, A.A. Voevodin (Air Force Research Laboratory) Pulsed Laser Deposition (PLD) and Magnetron Sputtering (MS) are being used in conjunction with process control to deposit thin-films for advanced structures. Closed loop feedback control, based on plume emissions, is used to update both the laser and magnetron power settings simultaneously to regulate the plume emissions for extended durations.
2:50 PM		B6-1-5 Industrial Laser-Arc Coater for the Deposition of Superhard Amorphous Carbon Films (Diamor) H.-J. Scheibe, A. Zwick, T. Stucky, C.-F. Meyer, H. Schulz, M. Schwach, B. Schultrich (Fraunhofer IWS, Germany) Thin amorphous carbon films (Diamor), deposited at room temperature through laser-assisted cathodic arc evaporation (LaserArco process), have shown unique properties of great relevance to engineered surfaces for wear and corrosion protection. The high-modulus (> 600 GPa) coatings are superhard (80GPa) with a low coefficient of friction (0.1 dry against steel). The vast variety of potential applications includes cutting and forming tools as well as components in rolling or sliding contact situations. The LaserArco plasma source and the Diamor deposition process have proven to be consistently reliable on the laboratory scale. Extended application development yielded to an increasing demand for the Diamor coating. Subsequently, the further development aimed at scaling up the technology to industrial dimensions. These requirements implied the extension of the laboratory technology to a target length of 1,200 mm for large area coatings as well as the capability of handling coating batches of up to 2 metric tons in total mass. As a result a newly designed LaserArco plasma source was integrated into a high volume production coater. In a subsequent step the actual Diamor deposition process was transferred from the laboratory, which for the first time enabled the application of Diamor coatings on an industrial scale. The currently ongoing process development focuses on high-modulus coatings at elevated substrate temperatures to enable the combination of classic hard coatings such as (Ti,Al)N as a base layer with Diamor as a top coating without process interruptions. So far a Young's modulus of 490 GPa for a Diamor coating deposited at a substrate temperature of 200° C has been achieved, a very promising result for future applications of superhard amorphous diamond films.
3:10 PM		B6-1-6 Study of Mechanical and Tribological Properties of WC/TiC and WC/B₄C Multilayer Films Deposited by Pulsed Laser Deposition A.R. Phani, J.E. Krzanowski (University of New Hampshire); J.J. Nainaparampril (Systran, Inc.) Ceramic/ceramic multilayers have the potential to provide high fracture toughness and hardness in thin-film coatings. In this paper we present the results of an investigation on the effects of compositionally modulated WC/TiC and WC/B₄C films on mechanical properties and film microstructure. Compositionally modulated WC/TiC and WC/B₄C films were deposited onto Si (111) and 440°C steel substrates at 400°C using the pulsed laser deposition (PLD) method. The film hardness was measured by nano-indentation, while x-ray photoelectron spectroscopy (XPS) was used to determine the film composition using depth profiling. Film morphology and roughness were measured by SEM and AFM techniques, respectively. Modulation periods examined in this investigation were 20, 10, 5, 2.5 nm of WC and with 10nm TiC and B₄C maintained constant in the deposited multilayers. Single layer films of TiC, B₄C and WC were also deposited by PLD for comparison. It was found that the film with lower modulation periods yielded a lower hardness value than single layer TiC, which may be due to compressive stress inside the deposited films. The results obtained in this investigation indicate that the hardness of compositionally modulated WC/TiC and WC/B₄C multilayer films strongly depend on modulation frequency. Tribological properties performed on steel substrates were also studied and will be discussed.
3:30 PM		B6-1-7 Using Lasers for the Production of Ceramic Coatings S. Nowotny, A. Richter, R. Zieris, E. Beyer (Fraunhofer Institute for materials and Beam Technology, Germany) New lightweight applications in the automotive and aircraft industries require advanced materials and techniques for surface treatment of the related components. For wear or corrosion protection as well as for thermal isolation, oxide ceramics are of special interest because of their low specific weight, low thermal conductivity, high chemical stability, and good tribological properties. Currently, plasma spraying is the established technique for the production of thick protection layers on aluminium, titanium, and magnesium alloys as well as on nickel alloys or steel. The applications of plasma spraying are however limited by the restricted adhesive strength, the typical layer porosity, and the inability to localize the coatings precisely. Against this background, laser based cladding techniques are additional solutions in such cases, where the sprayed coatings do not meet the requirements of the actual application. By using one-step laser cladding, completely dense and accurately shaped ceramic tracks and coatings, e. g. of Al2O₃/TiO₂ or ZrO₂/Y₂O₃, can be deposited with a thickness of up to 1 mm onto metallic substrates. Normally, these claddings show a fine-crystalline cast structure and a homogeneous network of vertical cracks. The adhesion strength exceeds that of plasma sprayed coatings by at least a factor of 2. Though the deposition rate is comparatively low. For large area claddings and higher deposition rates, the new technique of laser/plasma hybrid spraying is a promising technical variant. Compared to coatings sprayed without laser assistance, the porosity is less and the preliminary effort of the surface preparation is reduced considerably. Additionally, in some cases no metallic bond coat is necessary to reach a sufficient adhesion strength. Examples of applications are pump housings of car engines, turbine blades, and wire-guiding discs of elevating systems.
3:50 PM		B6-1-8 Femtosecond Pulsed Laser Deposition of Diamond-like Carbon Films for Tribological Applications F. Garrelie, A.N. Loir, C. Donnet, F. Rogemond, R. Le Harzic (University J. Monnet, France); M. Belin (Ecole Centrale de Lyon, France); E. Audouard, P. Laporte (University J. Monnet, France) Pulsed laser ablation is a well-known technique used for thin film deposition of hard and wear resistant Diamond-Like Carbon (DLC) films. Most of the previous studies have been performed by using pulse duration in the nanosecond range. The present study has been performed by ablating graphite targets with femtosecond (10-15s range) laser pulses. Compared to conventional nanosecond laser ablation, femtosecond laser allows the production of high energy (up to a few keV) ions in the plasma, which may strongly affect the structure and properties of the deposited films. DLC films have been deposited under vacuum onto (100) p-type silicon substrates at room temperature, by ablating graphite targets with femtosecond laser pulses. The 800nm, 150fs laser pulses have been generated by a mode-locked Ti : sapphire laser, including a regenerative amplifier. The pulse energy was 1.5mJ at a repetition rate of 1kHz. The fluence range was between 1 and 18 J/cm2. The nature and properties of the films have been characterized by various techniques, including XPS, TEM/EELS, AFM, scratch test and nanoindentation. The tribological behavior of the films have been also investigated in a pin-on-plate configuration. Correlations between the structure of the films and some of their properties are highlighted, depending on the deposition conditions. Discussion is focused on the comparison between present results obtained using the femtosecond mode, with previously published results related to DLC films deposited using the nanosecond mode.