• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.166-173
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• 1996

There are kinds of materials for protective heat shield, i.e.Zn-coated steel, AI-coated steel and aluminum alloy sheets. This study compare formability, corrosion resistance, heat protectability, weight, and cost of these materials for heat protective shield. Generally aluminum alloy sheets are less formable than steel sheets, but A1100 alloy sheet shows almost same press quality of steel parts, using the press dies which producing steel parts. The heat shields using aluminum alloy sheet and steel sheet show almost same heat protectibility. It is the conclusion that Zn-coated merit, and AI-coated steel sheet and aluminum alloy sheet can be used to protect functional corrosion in severely corrosive market area. The material cost of AI-coated steel sheet and aluminum alloy sheet for a mid-size car is almost same, so aluminum alloy sheet is more recommendable in the point of weight reduction of vehicle.

• Analytical Science and Technology
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• v.14 no.6
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• pp.494-498
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• 2001

In this study, cerium nitrate was used as an alternative to chromate for the surface-treatment of Al coated steel to improve the corrosion resistance. The surface of Al coated steel was characterized by means of a X-ray photoelectron spectroscopy(XPS). It was found that cerium on the surface of Al coated steel had a mixture of oxidation states such as Ce(+4) and Ce(+3), and the relative concentration of each state was 57 % and 43 %, respectively. The surface film consisting of these cerium compounds played an important role for achieving the corrosion resistance of Al coated steel.

• Corrosion Science and Technology
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• v.2 no.4
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• pp.165-170
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• 2003

Atmospheric corrosion behaviors of Zn, Zn-5%Al and Zn-55%A l coated steels have been investigated under cyclic wet-dry environments containing chloride ions. The wet-dry cycle was carried out by alternate exposure to immersion in 0.5 M (or 0.05 M) NaCl solutions and drying at $25^{\circ}C$ and 60 %RH. The polarization resistance $R_p$ and solution resistance $R_s$ were monitored by AC impedance technique. From the obtained $1/R_p$ and $1/R_s$ values, the corrosion rate of the coatings and the Time of Wetness (TOW) were estimated, respectively. Effects of chloride ions and TOW on the corrosion rates of Zn, Zn-5%Al, Zn-55%Al coatings and appearance of red rust (onset of underlying steel corrosion) under wet-dry cycles are discussed on the basis of the corrosion monitoring data.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.88-93
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• 2005

Ti-AI-Si-N coating layers were deposited on WC-Co substrates by a hybrid system of arc ion plating and sputtering techniques. The coatings were prepared with different Si contents to investigate the effect of Si content on their mechanical properties and microstructures. The dry sliding wear experiments were conducted on Ti-AI-Si-N coated WC-Co discs at constant load, 3N, and sliding speed, 0.1 m/s with two different counterpart materials such as steel ball and zirconia ball using a conventional ball-on-disc sliding wear apparatus. In the case of steel ball, the friction coefficient of Ti-AI-Si-N coating layers became lower than that of Ti-AI­N coating layers. The friction coefficient decreased with increasing of Si content due to adhesive wear behavior between coating layer and steel ball. On the contrary, in the case of zirconia ball, the friction coefficient increased with increasing of Si content, indicating that abrasive wear behavior was more dominant when the coating layers slid against zirconia ball.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.69-78
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• 1978

It is well known that the aluminizing steel is excellent in corrosion resistance and heat resistance. Therefore it has been used as boiler parts, heat exchanger parts and guide rails which are used under comparatively simple conditions. Recently, it has been noticed that aluminizing steel has high resistance to various atmosphere, high temperature oxidation and seawater resistance. So its usage has been extended widely to the production of parts such as intake and exhaust valve of internal combustion engine, turbine blade and pipelines On ships which required such properties. It is considered that aluminium coated steel is excellent in wear resistance because of high hardness on main ingredient FezAIs of Fe-AI alloy layer existed in diffusion coating layer. And it will beused as a new material taking wear resitance with seawater resistance in marine field. However it is difficult to findout any report concering the wear behaviors or properties of alum in izing steel. In this study the experiment was carried out under the condition of rolling-sliding contact using an Amsler-type wear testing machine at 0.80, 0.91, 1. 10, 1. 25% of slip ratio and 55.43, 78.38, 110.85 kg/mm^2 of Hertz's contact stress in run-in period for the purpose of service-ability test of aluminizing steel as a wear resisting material and obtaining the available design data. The followings are the obtained results from the experimen tal study; 1) The 2nd diffusion material has most excellent wear resistance. This material has brought out about 18% decrease of wear weight in a lower friction load level and 40~G decrease in a higher level comparing to the raw material. 2) Satisfactory effect of wear resistivity cannot be much expected in 2nd diffusion specimens. This is considered due to the formation of fine void in the alloy layer near the boundary to the aluminium layer. 3) Fracture on friction surface of aluminizing steel by the rolling-sliding contact is spalling, and spalling crack occurres initially beneath the specimen surface near the boundary in diffusion coating layer.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.9-10
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• 2000

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-AI, AI-Zn and AI-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 [1.2], however, in particular due to uncontrollable Slag-impurities within the hot bath [3], slide bearings are still expected to be of a higher potential [4]. The today's state of the art is the application of slide bearings based on Stellite\ulcorneragainst 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 [5.6.7.8] 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 AI-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. Outlook: Part II of this work will describe the field test in a hot-dip-galvanizing/aluminizing plant of the mechanically alloyed bearing bushes under aluminum-rich liquid metal. Alter testing, the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed. Part III of this project will describe a second initial testing phase where the won results of part 1+11 will be transferred to the AI-Si system. Part IV of this project will describe the field test in a hot-dip-aluminizing plant of the mechanically alloyed bearing bushes under aluminum liquid metal. After testing. the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed.