Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metal corrosion protection,metal surface treatment > Corrosion control and protection > Metal surface protection technology > Inorganic complex layer of protection > Ceramic stratified

Research on the Fabrication and Preperties of Ceramic Coatings on NiCr Alloy Surface by MAO

Author ZhangZuoJia
Tutor YuDeZhen
School Harbin Institute of Technology
Course Materials Physics and Chemistry
Keywords NiCr alloy Micro-arc oxidation Bond strength Ni ions
CLC TG174.453
Type Master's thesis
Year 2009
Downloads 26
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NiCr alloy in the oral environment will release the Ni ions, causing problems with security; NiCr alloy in order to improve the corrosion resistance, reducing the amount of Ni ions in precipitation, the paper uses micro-arc oxidation technology NiCr alloy prepared in low Ni content The Al 2 O 3 film. Using SEM, EDS, XRD film surface morphology method, cross-sectional shape, the element content, and phase were studied by tensile tests, electrochemical measurement techniques, Ni ion elution test were investigated the binding strength of the film , corrosion resistance and coating of Ni ions influence the amount of precipitation. Research shows that in NaAlO2 electrolyte concentration on micro-arc oxidation NaAlO2 film surface morphology greater impact; film surface element content of Ni 2 4 at%; film mainly amorphous form exists, a small amount of γ-Al 2 O 3 phase composition, the diffraction peak intensity increased with the increase NaAlO2 concentration. In NaAlO2-Na5P3O10 electrolyte system Na5P3O10 concentration on the surface morphology of micro-arc oxidation film has a greater impact; With reaction time, reduce the number of coating the surface of the pores, pore size; film thickness as Na5P3O10 concentration increases, the forward voltage increases and the reaction time is increased; the content of Ni in the surface layer 4 8 at%; layer mainly composed of γ-Al 2 < / sub> O 3 phase composition, the diffraction peak intensity Na5P3O10 concentration increases, the forward voltage increases and the reaction time is enhanced. Prepared in NaAlO2 electrolyte film and the bonding strength with the increase of the concentration of NaAlO2, up to 14.6MPa; at 12.3g / L NaAlO2-1g / L Na5P3O10 electrolyte system, the forward voltage of 380V , and the reaction time was 30min, the resulting film and the bonding strength of 21.5MPa, Na5P3O10 concentration is too low or too high, the forward voltage, load voltage and the negative long reaction times of the film and the bonding strength of the matrix reduced. Micro-arc oxidation film NiCr alloy improves the corrosion potential, has little effect on the corrosion current density, can inhibit the release of Ni ions. At 12.3g / L NaAlO2-1g / L Na5P3O10 electrolyte system, the forward voltage is 380V, the reaction time was 30min, the resulting film and the substrate compared to the corrosion potential improved 275mV, Ni ion release was reduced 55 %. Na5P3O10 concentration is too low or too high, both the forward voltage of Ni ion elution volume; long reaction time for the increase of precipitation amount of Ni ions.

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