Corrosion Resistance In H2SO4 Solution Research Articles

Porous TiFe intermetallic fabricated by reactive synthesis of elemental powders

Industrial applications for filtration and separation require the design of a porous material with low cost and strong corrosion resistance. Herein, porous TiFe intermetallic was fabricated by the reactive synthesis of elemental powders. The pore formation and phase transformation of porous TiFe intermetallic were investigated, and the corrosion behavior of porous TiFe intermetallic in 0.5 mol/L H2SO4, 3.5 wt% NaCl, and 1 mol/L KOH solutions was studied by electrochemical tests. The synthesized porous TiFe intermetallic formed by the diffusion reaction of Ti and Fe has a highly porous structure with open porosity of 57.6%, which is the result of a combination of the gap between powder particles and the Kirkendall effect. The porous TiFe intermetallic exhibits good corrosion resistance in H2SO4 solution, furthermore, it shows better corrosion resistance than 316L stainless steel in both KOH and NaCl solutions, which is related to its larger resistance, more positive corrosion potential, lower corrosion current density, and wider passivation regions. The synthesized porous Fe-based intermetallic exhibits an excellent corrosion resistance and structure stability in acid, salt and alkaline environments, and thus exhibiting its potential in the field of filtration and separation.

Study on corrosion and wear behavior mechanism of Zr-based bulk amorphous

The adsorption behavior of oxygen on Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) (001) and Zr (110) surfaces is studied by DFT First-principles calculations method. In addition, electrochemical corrosion and wear tests were used to study the corrosion and wear mechanism of Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) and Zr-1. The results indicate that the absorption energies of O at the top of Ti and Zr atoms are larger that of O at top of Cu and Ni atoms, which indicates that O at Ti and Zr atoms is more stable than that of O at Cu and Ni atoms. The O-Zr covalent bond formed by O adsorption on the Zr(110) surface has a maximum layout (0.24) at the bridge site, and the covalent bond formation is stronger and the adsorption is more stable. The corrosion current density of Vit1 is lower than that of Zr-1. The passivation film formed by ZrO2, TiO2, CuO and other components of Vit1 has higher corrosion resistance in H2SO4 solution, and the corrosion resistance of Vit1 is stronger than that of Zr-1. In addition, the wear performance of Vit1 is better than that of Zr-1. The results will provide an important guide to the corrosion and wear resistance of Zr-based bulk amorphous materials.

Electrochemical corrosion behavior of hot-pressing sintered WC-Al2O3 composite in alkaline and acidic solutions

In this study, WC-Al2O3 composite was fabricated by vacuum hot-pressing sintering. The corrosion behavior of WC-Al2O3 composite in NaOH and H2SO4 solutions was investigated by electrochemical measurements. The corrosion mechanisms were analyzed and revealed in light of corrosion morphology observation and composition characterization. The results confirmed that WC-Al2O3 composite possessed higher corrosion resistance than WC-Co hard metal in H2SO4 solution. Conversely, WC-Al2O3 composite behaved similar corrosion resistance compared with WC-Co hard metal in NaOH solution. The key reason for higher corrosion resistance in H2SO4 solution is the stable WO3 passive film. The oxidation of WC phase leads to neck cracks along with grain boundaries, which is attributed to the preferential corrosion of grain boundary and the stress derived from the volume expansion during polarization and drying processes. In NaOH solution, the corrosion mechanism of WC-Al2O3 composite mainly attributed to the dissolution of WC phase, but Al2O3 phase is relatively stable.

The study of corrosion behavior of WC-MgO composite in H2SO4 and NaOH solution

The corrosion behavior of WC-MgO composite in H2SO4 and NaOH solution has been studied with electrochemistry and microstructure analysis method. The aim of this work is to explore the corrosion behavior and mechanism of WC-MgO whisker composite in acid and alkali solution. The result suggests that WC-MgO composite possesses higher corrosion resistance in H2SO4 solution than in NaOH solution. The key reason for better corrosion resistance in H2SO4 solution is the stable WO3 passive film. The oxidation of WC leads to corrosion induced crack along with grain boundaries. It can be attributed to the preferential corrosion of grain boundary and volume expansion caused by WC phase oxidation. The corrosion induced crack on the surface may decrease mechanical properties of WC-MgO composite. In NaOH solution, the main corrosion mechanism is the dissolution of WC phase but MgO is relatively stable.

Surface Grain Refinement of 304L Stainless Steel by Combined Severe Shot Peening and Reversion Annealing Treatment

The present study proposes a novel method, i.e., combined severe shot peening (SP) and reversion annealing treatment, to grain-refine the surface layers of 304L austenitic stainless steel. Steel specimens were shot-peened at 0.7 MPa for 30 min, introducing 40% vol. α′ martensite, and then were annealed at 700 or 800 °C for different durations (30 s). As annealing reversed α′ martensite to austenite, the obtained surface layers consist of fully austenitic ultrafine grains. The smallest grain size obtained is about 500 nm at the top surface. SP elevates the microhardness to more than 500 HV. Although the grain-refined surface layers produced by the combined method are not as hard as that treated by only SP, they are harder (e.g., the specimen annealed at 700 °C for 30 s using a heating rate of 50 °C/s exhibited a peak microhardness of 400 HV) than the untreated surface layer (225 HV) due to grain refinement. Moreover, due to the absence of α′ martensite, they have higher corrosion resistance in H2SO4 solution than that treated by only SP.

Crystallization and Corrosion Resistance in Different Aqueous Solutions of Zr50.7Ni28Cu9Al12.3 Amorphous Alloy and Its Crystallization Counterparts

The Zr50.7Ni28Cu9Al12.3 amorphous alloy and its crystallization counterparts have been prepared using a melt spinning technique and proper annealing treatment. The as-annealed products at 768 K are amorphous composites consisting of a main amorphous phase and a few ZrO2 nanocrystals. The corrosion behaviors have been investigated in 0.5-M NaCl, 1-M HCl, and 0.5-M H2SO4 solutions. The results show that amorphous composites present the enhanced corrosion resistance in Cl− containing solutions due to the formation of compact passive films, which are promoted by an appropriate quantity of ZrO2 nanocrystals. Nevertheless, the relaxed samples possess good corrosion resistance in H2SO4 solution, which is attributed to the existence of Zr(Al, Ni)-rich protective film induced by the depletion of Cu. In addition, corrosion resistance of the tested alloys is relatively superior in H2SO4 solution, especially for pitting corrosion resistance, and inferior in HCl solution.

Protection of stainless steel in hydrochloric acid solution containing hydrogen sulfide by inhibitors

The corrosion of chromium-nickel steel 1Kh18N9T in 2 М H2SO4 at t = 20–100°C was studied using the mass loss method. In addition, steel hydrogenation in the corrosive medium was measured by the vacuum extraction method. IFKhAN-92 (a 1,2,4-triazole derivative) and its combination with KI were studied as corrosion inhibitors. It was shown that 1Kh18N9T steel has low corrosion resistance in H2SO4 solutions, particularly at temperatures (t) close to 100°C. The steel corrosion rate is k = 1.7–727 g/(m 2 h) under the conditions studied and increases with increasing t. Steel hydrogenation occurs at t = 40– 100°C and is the strongest at 100°C (12 ml / 100 g). The presence of 15 mM H2S in the H2SO4 solution slows down steel corrosion (k = 2.8–274 g/(m 2 h)) but intensifies hydrogen absorption. The highest content of hydrogen absorbed in the metal (36 ml / 100 g) was observed at t = 40°C and 1 h exposure of the specimens. It has been shown that, by themselves, 5 mM IFKhAN-92 or 5 mM KI are not suitable for protection of 1Kh18N9T steel in the specified media, since IFKhAN-92 has low efficiency in H2SO4 solution without H2S, whereas, conversely, KI has low efficiency in H2SO4 solution containing H2S. However, their mixture shows versatile protection in these media. The formulation containing 2.5 mM IFKhAN-92 + 2.5 mM KI that suppresses steel corrosion in H2Scontaining medium up to 100С and totally prevents hydrogen absorption up to 60°C, inclusive, has been recommended for steel protection in H2SO4, both in the absence and in the presence of H2S. This mixture is particularly efficient in solutions without H2S where it inhibits steel corrosion in the entire t range studied while keeping the content of hydrogen in the metal at metallurgical level.

Corrosion and Serration Behaviors of TiZr0.5NbCr0.5VxMoy High Entropy Alloys in Aqueous Environments

The corrosion and serration behaviors of TiZr0.5NbCr0.5, TiZr0.5NbCr0.5V and TiZr0.5NbCr0.5Mo high entropy alloys (HEAs) in NaCl and H2SO4 solutions were studied by potentiodynamic polarizations (PP) and immersion tests. The results show that all the alloys display excellent corrosion resistance no matter in NaCl solution or in H2SO4 solution. The additions of V and Mo increase the pitting corrosion resistance for the three alloys in NaCl solution slightly and greatly improve the corrosion resistance in H2SO4 solution. The corrosion behaviors of TiZr0.5NbCr0.5 and TiZr0.5NbCr0.5Mo alloys are more sensitive to temperature than that of TiZr0.5NbCr0.5V alloy. After immersion, the surface of TiZr0.5NbCr0.5 alloy appears some pitting holes, this may be related to the electrochemical noise and serration behavior on PP curves; localized corrosion initiates mainly on the boundaries of the BCC and Cr2Zr Laves phase for TiZr0.5NbCr0.5V alloy; while for the TiZr0.5NbCr0.5Mo alloy, the dendrites with Mo element rich region exhibit poor corrosion resistance.

Microstructure and Corrosion Resistance of Fe-Based Amorphous Coating Prepared Atmospheric Plasma Spraying

Fe-based amorphous coating was prepared on stainless steel substrates by atmospheric plasma spraying (APS) using Fe-based amorphous powder as feedstock. Microstructures of the coating were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM). The corrosion behavior of coating and stainless steel were evaluated respectively in 3.5% NaCl, 10% NaOH and 1 mol/L H2SO4 aqueous solutions by electrochemical workstation. The results indicated that the coating was composed of most amorphous phase and some Fe-Cr crystalline phase. The coating exhibited the better corrosion resistance in H2SO4 solution, while the worse in NaOH.

Corrosion Behavior of Cu<sub>60</sub>Zr<sub>30</sub>Ti<sub>10</sub> Amorphous Alloy

The ribbon samples for Cu60Zr30Ti10 (at. %) with a thickness of 50 μm and a width of 13 μm were prepared by melt spinning at the wheel speed of 30 m/s. The glassy structure was confirmed by X-ray diffraction (XRD) using Cu Kα radiation. The corrosion property and corrosion mechanism in 1 M HCl, 1 M NaCl, and 0.5 M H2SO4 solutions were investigated by electrochemical polarization measurement. The corrosion mechanisms are dominated by the pitting corrosion in H2SO4 solution and the pitting and uniform corrosion in HCl and NaCl solutions. In addition, the corrosion resistance in H2SO4 solution is better than that in HCl and NaCl solutions. Cu60Zr30Ti10 glassy alloy in H2SO4 solution is nobler than in HCl and NaCl solutions.

Ｎｉ３Ｓｉ系金属間化合物のミクロ組織に及ぼすＭＡ条件並びに熱処理条件の影響

It is well known that Ni3Si intermetallic compounds have an excellent corrosion resistance in H2SO4 solution. However, practical production has been difficult because of poor ductility caused by very brittle phase which is liable to be formed. Therefore, the process conditions involving a mechanical alloying(MA) technique were investigated in order to obtain final products composed of Ni3Si stoichiometric single phase compo-und by suppressing the formation of brittle phase. In this paper, fine Ni-Si composite powders which have been prepared by the MA method were hot extruded, thereafter β phase - Ni3Si consolidates were obtained by a specific heat treatment. The influence of compositions, MA conditions and heat treatment conditions for obtaining the β single phase - Ni3Si intermetallic compounds were investigated. It was confirmed that consolidates of Ni3Si intermetallic compounds with almost single phase(β phase) can be obtained under the following conditions: composition of 13.1 mass%Si and 86.9 mass%Ni, MA(B/P=16) for 346ks, extrusion at 1223K and heat treatment at 1223K for 18ks.