Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Aluminizing

Optimization of Hot-Dip Aluminizing Process Parameters of AISI 303 Stainless Steel Using RSM

Ahmed Naif Al-Khazraji; Samir Ali Al-Rabii; Hameed Shamkhi Al-Khazalli

Engineering and Technology Journal, 2015, Volume 33, Issue 9, Pages 2130-2145

The coating thickness is an important factor to evaluate the coating quality and determining the properties of the hot-dip aluminizing (HDA)coating. In the present work, a hot dipping pure aluminum (99%) on stainless steel (AISI 303) rods was carried out for different diameters of rods (8, 10 and 12mm) and different lengths (250 and 500 mm) at different aluminizing conditions of temperature and time. The dipping temperature was set to 700, 740, 780, 820 and 860℃ .The dipping time was set to 1, 2, 3,4 and 5 minutes. A response surface methodology (RSM) using a central composite rotatable design (CCD) for a 2³ factorial, with 5 central points and α = ±2 approach, based on the experimental data, was used to obtain the optimum modelto get the best thickness of coating and the best conditions of dipping. A 2nd polynomial model was obtained with a confiding percentage of 95%.Analysis of the experiments using RSM indicated that 807℃ and3minare optimum dipping conditions for hot-dip aluminizing process with corresponding thickness of coating layers of 134 μmto Al layer,62.9 μm to intermetallic compound (IMC) layer and 197μm to total coating layer.

Neural NetworkModeling of Oxidation Kinetics in Air of Steel-T21 Alloy Coated by Simultaneous Germanium-Doped Aluminizing-Silicon zing Process

Abbas Khammas; Mohanned M. H.AL-Khafaji

Engineering and Technology Journal, 2013, Volume 31, Issue 4, Pages 632-645

In this work a pack cementation of germanium-doped aluminum and silicon coatings on low alloy steel type-T21 has been applied. This gives significant improvement in the oxidation. Steel-T21 was coated with germanium-doped aluminizing-siliconizing. Diffusion coating was carried out at 1050oC for 6 h under an Ar atmosphere by simultaneous germanium-doped aluminizing-siliconzing process. Cyclic oxidation tests were conducted on the coated steel-T21 alloy in the temperature range oxide 300-900oC in air for 102 h at 3 h cycle. The results showed that the oxidation kinetics for coated system in air can be represented by parabolic curve .Oxide phases that formed on coated system are SiO2 and Cr2O3. A neural network model of oxidation kinetics has been proposed to model the oxidation kinetic. The neural model shows good agreement with the experimental data.