Effect of Sintering Atmosphere on the Corrosion and Wear Resistance of Sol-Gel Alumina-Coated Mild Steel Surface

Abstract

Sol-gel boehmite coating has been applied on mild steel substrate and sintered in inert (nitrogen) and oxygen atmospheres at 400°C to obtain a crack-free and dense alumina coating. Thereafter, its corrosion and wear resistance properties were evaluated under different exposure conditions. Fourier transform infrared (FTIR) analysis of the boehmite gel sintered in the above-mentioned atmospheres identified the presence of residual organic precursors in the gel. Microstructure and phase analyses of the sol-gel-coated surfaces were carried out using scanning electron microscopy (SEM) and x-ray diffraction (XRD) analyses, respectively. XRD analysis confirms the presence of alumina phase on the sol-gel-coated surfaces. Traces of organic groups in the gel sintered at 400°C in both of the atmospheres were noticed by FTIR analysis. Solgel-coated specimens sintered in a nitrogen atmosphere have shown a somewhat better corrosion resistance in 3.5% sodium chloride (NaCl) as compared to specimens sintered in an oxygen atmosphere. Similarly, an improved wear resistance was measured for the sol-gel-coated specimens sintered in the nitrogen atmosphere.

Effect of sol–gel prepared nanoalumina reinforcement content on the corrosion resistances of Al 6061‐Al2O3 nanocomposite in 3.5% NaCl solution

“…After stirring for 12–14 h, the whole suspension became bluish white color colloidal boehmite (AlOOH) gel. The details of the synthesis of the boehmite gel using sol–gel process is available elsewhere . After air drying, boehmite gel was dried again in a heating oven at 100 °C for 4 h. The dried gel was grinded in a mortar pestle till uniform coarse size particles form.…”

“…The details of the synthesis of the boehmite gel using sol-gel process is available elsewhere. [28] After air drying, boehmite gel was dried again in a heating oven at 100°C for 4 h. The dried gel was grinded in a mortar pestle till uniform coarse size particles form. Powdered boehmite was sintered in muffle furnace at 1200 ± 10°C for 2 h to convert it into alpha alumina.…”

“…In the present sol-gel synthesis, firstly boehmite gel was formed after completion of hydrolysis, peptization, and condensation reactions as described elsewhere. [28] Boehmite is reported to transform into alpha alumina phase after heating at >1150°C. [21][22][23] Transformation of boehmite to alumina can be expressed as per following reaction (1)…”

Sol–gel synthesis of nanoparticles of gamma alumina and their application in defluoridation of water

“…Based on Yoldas process [28], boehmite gel was synthesized using aluminum isopropoxide and double-distilled water in their 1:100 molar ratio. Details of synthesis of boehmite are available elsewhere [29,30]. After drying, it was calcined in muffle furnace for 1 h at 500°C.…”

Corrosion resistance of sol–gel alumina coated Mg metal in 3.5 % NaCl solution

“…on the different types of steel and stainless steel substrates [18][19][20][21][22][23][24][25][26][27]. Singh et al [28][29][30] observed a significant improvement in the corrosion and pitting resistances of sol-gel alumina coated low carbon steel, 9Cr 1Mo ferritic steel and 304 SS in highly corrosive NaCl solution. In comparison, relatively few study has been reported in the development of sol-gel based ceramic oxides coating on Mg alloys [31][32][33][34][35][36].…”