ICMCTF2007 Session G1-1: Innovations in Surface Coatings and Treatments

Tuesday, April 24, 2007 8:00 AM in Room Royal Palm 4-6

Tuesday Morning

Start	Invited?	Item
8:00 AM	Invited	G1-1-1 Industrial Production of PVD Coatings for Tools and Components T. Krug, R. Tietema (Hauzer Techno Coating BV, Netherlands) Today PVD coating has developed into a standard production technique, where millions of parts, used in decorative, tooling and automotive applications are coated on a regular base with an added value of more than one billion US dollers per year. While in tool coating the consequential damage in case of failures in the coating are limited mainly to the tool coating itself, the consequential damage of failures in the coating of automotive parts can end in recalls of delivered cars and therefore can easily reach millions of dollars. Therefore, all process steps in a PVD production cell, starting from delivery until shipment to the customer, have to be qualified and frozen in the relevant quality handbook to achieve a zero defect production. The experience and conclusions of a supplier of PVD production cells is presented in this paper.
8:40 AM		G1-1-3 RF Plasma Enhanced Cylindrical Magnetron Sputter Deposition R. Wei (Soutwest Research Institute); S.L. Lee (Army Benet Lab) In this paper, we present a newly developed technology - RF plasma enhanced magnetron sputtering. Using this technology the bore of a cylinder can be deposited with metallic or ceramic coatings. The technology utilizes a cylindrical magnetron with the magnets being arranged longitudinally and rotated around the center of the magnetron. In this way, conventional low-cost rectangular magnets can be used and the target can be sputtered uniformly with high utilization. An RF antenna is placed between the magnetron and the bore of the cylinder to achieve the plasma enhancement. The current density thus produced is over ten times higher than that without the RF enhancement. In this paper, the design and construction of the cylindrical magnetron system will be discussed. The arrangement of the RF antenna and the characteristics of the RF plasma will be presented. Using the set up, Ta coatings were deposited onto steel samples mounted on the bore. The coatings were characterized using a scratch tester for adhesion, microhardness tester for hardness, SEM for morphology, and XRD for microstructure. Special techniques, which were developed for cleaning both surfaces of the cylinder bore and the magnetron target, will also be discussed in the paper.
9:00 AM		G1-1-4 Room-Temperature Industrially-Scaled Pulsed Laser Deposition of Coatings for Wear-Protection, Low-Friction, Decorative and Biocompatible Applications W. Waldhauser, J.M. Lackner, M. Kahn, R. Berghauser, D. Hufnagel (Laser Center Leoben, Austria) Increasing demands on dimension accuracy and, thus, the minimization of distortion during coating as well as the increasing application of high-strength, but low temperature-resistant materials (plastics, polymer compounds, light metals) require low-temperature vacuum coating techniques. However, many of the presently used techniques like sputtering, arc evaporation, and PA-CVD techniques are not able to provide coatings at low deposition temperatures (< 100°C) with properties of high- or medium-temperature deposited coatings. In the field of PVD the Pulsed Laser Deposition (PLD) coating technique stands out against nearly all others by its unique feature of pulsed high- and low-energetic plasma flux, enabling even coating at room temperature (~ 25-40°C) with properties known only for elevated deposition temperatures (> 250°C). The present work emphasizes this feature of the PLD technique based on both scientific investigations of the adhesion strength and the tribological performance as well as on the behaviour of the coatings in selected industrial applications (decorative, biocompatible, optical). Furthermore, the possibilities of combining PLD with magnetron sputtering at room temperature (HybridPLD) for industrial demands are demonstrated on several examples. All work is done on industrially up-scaled coating equipment specially designed for PLD and HybridPLD by Laser Center Leoben, allowing both high-rate and large-area deposition. The results show generally high critical loads (> 40 N) in scratch tests and "adjustable" decorative and tribological properties (friction coefficients between 0.05 and 1.0) depending on the coating type (TiN, TiCN, TiO₂, CrN, CrCN, TiAlN, DLC, etc.). Due to the high wear resistance even in thin films and the high biocompatibility of the very pure coatings, the room-temperature deposited PLD and HybridPLD coatings are ideally in many coating applications of temperature-sensitive materials.
9:20 AM		G1-1-5 Sputter Power on the Antibacterial Capabilities and Microstructure of ZrAlNiCuSiB Thin Films on 304 Stainless Steel P.T. Chiang, J.Y. Yu, J.S.C. Jang, G.J. Chen, Y.H. Shih, S.H. Tseng (I-Shou University, Taiwan) Silver and copper are commonly elements with antibacterial property. Because silver (Ag) is too expensive as well as high concentration of ionized silver has some tissue-toxicity, it is necessary to find an alternative when the topical use in treatment of some kinds of bacterial or fungal infection. Copper has a lower cost, better antifungal ability, and higher chemical stability than those of silver. Copper based antibacterial materials can be good candidates. We modify the mechanical, corrosive and antibacterial properties of 304 stainless steel, which used in many tools, especial for living life, in hospital or in surgery. The investigation evaluates the effects of sputter power on the microstructural, mechanical, corrosive and antibacterial properties of ZrAlNiCuSiB thin films on 304 stainless steel. The amorphous feature of the ZrAlNiCuSiB thin films would be confirmed by glancing incident x-ray diffraction (GIXRD). The examination of EDS checked the compositions of thin films. The porosity and surface roughness are observed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. The scratch test checks the adhesive power between thin films and 304 stainless steel. Hardness test examines the hardness of ZrAlNiCuSiB thin films associated with sputtering power. The organisms such as Staphylococci, Streptococci, Pseudomonas aeruginosa, Mycobacteria, Escherichia coli, Candida Albicans and Mycobacteria are used in this study to evaluate ZrAlNiCuSiB thin films on 304 stainless steel bacteriocidal or bacteriostatic effects.
9:40 AM		G1-1-6 Fatigue Properties of Micro Arc Oxidation Coatings on Al Alloy N. Wasekar, N. Ravi, G. Sundararajan (International Advanced Research Centre for Powder Metallurgy and New Materials, India) Micro Arc Oxidation (MAO) also called as plasma electrolytic oxidation is gaining much interest in recent times for coating Al alloy surfaces because it is an ecofriendly technology to deposit hard wear and corrosion resistance alumina coatings. The present investigation deals with the fatigue properties of MAO coated 6061-T6 Al alloy. Approximately 10 µm and 50 µm coatings were deposited in an alkaline electrolyte at 0.1 and 0.3 A per cm² each. Coatings were characterized using SEM, X ray diffraction and surface roughness measurement. The fatigue tests were carried out using Rotating Bending Fatigue Tester (R=-1). About 16 % decrease in fatigue life was observed for the coatings deposited at 0.3A per cm², while it was 25% for the coatings deposited at 0.1 A per cm², as compared to bare substrate. The presence of residual stress generated during the deposition process was attributed to variable fatigue properties. It was observed that 10 µm thick MAO coating generated tensile residual stresses when deposited at both the current densities. This in effect makes the adjacent substrate under compression resulting in improved endurance compared to 50 µm thick coatings. However compressive residual stresses were observed in 50 µm coatings deposited at 0.1 and 0.3 A per cm². Possible fatigue crack initiation and propagation is also proposed.
10:00 AM		G1-1-7 Fe-Al Formation On the Surface of 45 Carbon Steel by Plasma Alumizing Z. Yao, P. Zhang, Z. Xu (Nanjing University of Aeronautics and Astronautics, China) Te-Al intermetallic has excellent corrosion resistance and good wear resistance, but poor embrittleness and processing properties limit its actual application. In this work, Fe-Al intermetallic alloy layer has been made on the surface of 45 carbon steel using double glow plasma surface alloying technology. Powder metallurgy Al/C plate is select as source electrode which supporting Al ion and atom. The effect of technique parameters like gas pressure, electron current density, working temperature etc. on coating thickness, microstructure, microhardness are researched. Experimental results show that compact Fe-Al alloying layer has Fe₃Al intermetallic phase, Al content and microhardness are gradually distributed along the case depth. The microhardness near the surface is 3 times to substrate. Comparing to pack cementation coatings, plasma alumizing has quick permeation speed and smooth surface morphology.
10:20 AM		G1-1-8 Thermal Sprayed Coatings of Aluminium Matrix Composites with sol-gel Silica Coated SiC Particles on Steels J. Rams, M. Campo, B. Torres, A. Ureña (Rey Juan Carlos University, Spain) Thermal spray is a technique suitable for laying metal coatings on many substrates to improve their wear and corrosion resistance, but its lack of energy usually causes problems to deposit composites and higher energy methods must be used. We have used this technique to deposit aluminium matrix composites reinforced with up to 30%vol SiC particles on AISI 304 stainless steel and on F112 carbon steel. The use of a low energy spray method has been possible because SiC particles have been coated by silica through a sol-gel route. Sol-gel silica laid on the particles is partially porous, and its reactivity with molten aluminium can be controlled by means of thermal treatments which modify its specific surface in the 1.75 to 74.65 m²/g range. This layer increases the wettability of SiC particles by molten aluminium allowing a complete matrix -reinforcement integration and reducing the porosity to values below 1%. Coatings with different reinforcement percentages in the 10%vol to 30%vol range have been produced with sol-gel silica coatings on the particles and without it, and using different thermal treatments for the sol-gel coatings. The morphologies, particle distribution, corrosion resistance, adherence and thermal properties of the coatings have been studied. The effects that reinforcement percentage, use of coatings on SiC particles, and thermal spray parameters have on the coatings laid on the different substrates have been analysed. Aluminium matrix composites reinforced with sol-gel treated SiC particles thermally sprayed on steels are suitable for increasing the corrosion resistance of the substrates while giving better thermal and mechanical properties than other coatings.
10:40 AM	Invited	G1-1-9 Present Status in Double Glow Plasma Surface Metallurgy Research Z. Xu (Nanjing University of Aeronautics and Astronautics, China); Z. He (Taiyuan University of Technology, China); P. Zhang (Nanjing University of Aeronautics and Astronautics, China) Based on the plasma nitriding technique, the Double Glow Plasma Surface Alloying/Metallurgy (DG-PSM) technique was developed in the 1980s. This technology is also known as the Xu-Tec Process, which utilizes any chemical elements including solid metallic elements such as Ni, Cr, Mo, W, Ti, Al, Nb, Zr, etc and their combinations to accomplish plasma surface alloying. A series of surface alloys have been produced by this technique including high speed steels, nickel base alloys, wear resistant alloys and burn (fire) resistant alloys on a wide range substrate materials, such as steels and iron, titanium and its alloys, intermetallic compounds, copper and its alloys, and conductive ceramics. The DG-PSM technology greatly expands the field of plasma surface alloying and also presents many challenging topics for researchers. Many of these issues are interdisciplinary including vacuum technology, low temperature plasma, glow discharge, and interactions between energetic particles and solid surfaces. Although a significant amount of progress has been made, it is far from fully understanding of the mechanisms of the process and precise control of the outcome of the alloying process. This paper will introduce the principles of the DG-PSM technology, review the current research status, discuss its advantages and future potential, and present practical application examples.