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Article
Corrosion Resistance Enhancement in Acidic solution for Austenitic Stainless Steel by Gas-Phase Hybrid Deposition Process

Authors: A.D. Thamir --- F.Q. Mohammed --- A.S. Hasan --- A.L. Abid
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 8 Part (A) Engineering Pages: 788-794
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In acidic environments the corrosion rate of stainless steels is considered high, this is due to pitting occurrence in concentrated chloride environments. The Austenitic steels such as type 316 stainless steel generally not recommended for Hydrochloric acid storage in petroleum planets except when solutions are very dilute and at room temperature, otherwise pitting may occur. In this work, a multicomponent coating (Ti-B-N-C) was deposited on the austenitic stainless steels (AISI 316) that used in petroleum industry. The coating process has been achieved by mixed vapor deposition technique; this was done in attempt to improve the resistance to pitting corrosion for austenitic stainless steels surface. The structural characterization for the deposited Ti-Base coating was done by using XRD technique, and the Scanning Electron Microscopy (SEM). Electrochemical corrosion tests have been performed by using electrochemical test in 0.25M hydrochloric acid (HCl) as an aqueous solution at 22˚C to obtain the anodic polarization curves for the coated surfaces. Several interesting observations have been made During the test. As expected, the surface of the AISI 316 suffers from a sudden increase in the current density at the potential above 1500 mV due to the occurrence of pitting corrosion. In addition, the Ti-B-C-N coating surfaces show great future in reducing the current density of the steel surface in the anodic region, indicating improved pitting resistance for all Ti-based coating samples. No evidence for pitting corrosion was observed in the coated surfaces during electrochemical test even at potentials up to 2000 mV, instead, general corrosion was observed for the samples that was deposited at 750˚C since low potential values was observed for these samples .


Article
Titanium-Base Nanostructure Coatings for AISI M52 Tool Steel by Gas-Phase Mix Process

Authors: F.Q. Mohammed --- A. J. Haider --- A.D. Thamir
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 3 Part (A) Engineering Pages: 182-189
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Deposition of Multicomponent hard coatings (Ti-B-N-C) on the molybdenum high-speed tool steel (AISI M52) has been achieved by mixed vapor deposition technique to improve the mechanical properties of the surface. In this technique the coating materials that were supplied in the gas phase were produced from powders that vaporized by thermal energy (that is, PVD- Reactive Evaporation Process), while the reactor that used to deposit Ti-Base coatings is hot-wall chemical vapor deposition (HWCVD) system equipment. This combination results in technical and financial advantages. The structure of deposited Ti-Base hard film was characterized by XRD technique, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray spectroscopy (EDX). Mechanical characterization of the hard films has been performed by using Vickers micro hardness tester and The Ball-on-disk wear tests. With different reactive gas flow rates that ranged from 500 to 3000Sccm(standard Cubic Centimeter per Minute), the film showed amorphous matrix with crystalline Nano fibers of Ti-B phase which led to achieve higher hardness of 2051HV and better wear resistance with relatively good COF values of 0.61 than the uncoated tools.

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