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Zeitschriftendaten
Format
Zeitschrift
eISSN
1804-1213
Erstveröffentlichung
03 Apr 2012
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 65 (2021): Heft 1 (May 2021)

Zeitschriftendaten
Format
Zeitschrift
eISSN
1804-1213
Erstveröffentlichung
03 Apr 2012
Erscheinungsweise
4 Hefte pro Jahr
Sprachen
Englisch

Suche

4 Artikel
Uneingeschränkter Zugang

Investigation on the microstructure, microhardness, and tribological behavior of AA1100-hBN surface composite

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 1 - 11

Zusammenfassung

Abstract

Aluminum alloy AA1100 has less wear resistance and mechanical properties than that of other aluminum alloys. This research work is on the fabrication of surface composites of AA1100 alloy by friction stir processing (FSP). The surface composites are fabricated by reinforcing hBN (hexagonal Boron Nitride) in AA1100 alloy to improve the mechanical and tribological properties. The influence of process parameters, rotational speed (rpm), and transverse speed (mm/min) on the microstructural evolution and properties of the fabricated surface composites is investigated.

Uneingeschränkter Zugang

Terephthalohydrazide and isophthalo- hydrazide as new corrosion inhibitors for mild steel in hydrochloric acid: Experimental and theoretical approaches

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 12 - 22

Zusammenfassung

Abstract

Most organic corrosion inhibitors have polar groups through which the molecule can be adsorbed strongly or specifically on the metal surface. In this investigation, terephthalo- hydrazide and isophthalohydrazide were synthesized as corrosion inhibitors, and their corrosion-inhibiting properties on mild steel were evaluated in a corrosive environment by weight loss measurements. The results of corrosion experiments revealed that terephthalohydrazide and isophthalohydrazide as inhibitors controlled or reduced corrosion through adsorption mechanism and showed inhibitive efficiencies of 96.4 % and 97.2 %, respectively, at the optimum concentration of 0.5 mM. The surface morphology of the metal was evaluated by scanning electron microscopy. The terephthalohydrazide or isophthalohydrazide molecules were adsorbed on the mild steel surface, and the process of adsorption follows chemical adsorption. Quantum chemical calculations of the tested corrosion inhibitors were consistent with the experimental observations.

Uneingeschränkter Zugang

Environmentally assisted cracking in the low pressure superheated hydrogen steam

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 23 - 32

Zusammenfassung

Abstract

Low pressure superheated H2-steam appears to be an interesting alternative to pressurized water environments, since it is capable of performing accelerated environmentally assisted cracking (EAC) experiments for nickel base and stainless steel alloys. Constant Extension Rate Tensile (CERT) tests were performed with displacement rates of 2×10-6 or 2×10-8 ms-1 at 350, 400, 440 and 480 °C on flat tapered specimens of Type 316L austenitic stainless steel. The tapered shape allows the determination of crack initiation over a range of stresses and strains simultaneously on one specimen and therefore the threshold stress value was obtained. The environment was 6 times more oxidizing than the dissociation pressure of NiO. The acquired mechanical properties are summarized and threshold stresses for EAC crack initiation are evaluated.

Uneingeschränkter Zugang

Simulation of boronizing kinetics of ASTM A36 steel with the alternative kinetic model and the integral method

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 33 - 39

Zusammenfassung

Abstract

In this study, two different mathematical models have been proposed for estimating the diffusivities of boron in the Fe2B layer on ASTM A36 steel in the range of 1173 to 1273 K with exposure times of 2 to 8 h. The boride incubation period required for the formation of such a layer was constant regardless of the boriding conditions. In both approaches, the boron diffusivity in the iron phase was considered in an unsaturated matrix. The first approach was derived from the mass balance equation at the (Fe2B/substrate) interface while the second approach employed the integral diffusion model. The calculated values of boron activation energies for ASTM A36 steel were found to be very comparable for the two approaches (161.65 and 160.96 and kJ mol-1). Afterwards, these values of activation energy were confronted with the results from the literature. Experimental validation of these two approaches has been done by comparing the experimental value of Fe2B layer thickness measured at 1123 K for 2.5 h with the simulated values. Finally, the predicted values of Fe2B layer thickness were in line with the experimental measurement.

4 Artikel
Uneingeschränkter Zugang

Investigation on the microstructure, microhardness, and tribological behavior of AA1100-hBN surface composite

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 1 - 11

Zusammenfassung

Abstract

Aluminum alloy AA1100 has less wear resistance and mechanical properties than that of other aluminum alloys. This research work is on the fabrication of surface composites of AA1100 alloy by friction stir processing (FSP). The surface composites are fabricated by reinforcing hBN (hexagonal Boron Nitride) in AA1100 alloy to improve the mechanical and tribological properties. The influence of process parameters, rotational speed (rpm), and transverse speed (mm/min) on the microstructural evolution and properties of the fabricated surface composites is investigated.

Uneingeschränkter Zugang

Terephthalohydrazide and isophthalo- hydrazide as new corrosion inhibitors for mild steel in hydrochloric acid: Experimental and theoretical approaches

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 12 - 22

Zusammenfassung

Abstract

Most organic corrosion inhibitors have polar groups through which the molecule can be adsorbed strongly or specifically on the metal surface. In this investigation, terephthalo- hydrazide and isophthalohydrazide were synthesized as corrosion inhibitors, and their corrosion-inhibiting properties on mild steel were evaluated in a corrosive environment by weight loss measurements. The results of corrosion experiments revealed that terephthalohydrazide and isophthalohydrazide as inhibitors controlled or reduced corrosion through adsorption mechanism and showed inhibitive efficiencies of 96.4 % and 97.2 %, respectively, at the optimum concentration of 0.5 mM. The surface morphology of the metal was evaluated by scanning electron microscopy. The terephthalohydrazide or isophthalohydrazide molecules were adsorbed on the mild steel surface, and the process of adsorption follows chemical adsorption. Quantum chemical calculations of the tested corrosion inhibitors were consistent with the experimental observations.

Uneingeschränkter Zugang

Environmentally assisted cracking in the low pressure superheated hydrogen steam

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 23 - 32

Zusammenfassung

Abstract

Low pressure superheated H2-steam appears to be an interesting alternative to pressurized water environments, since it is capable of performing accelerated environmentally assisted cracking (EAC) experiments for nickel base and stainless steel alloys. Constant Extension Rate Tensile (CERT) tests were performed with displacement rates of 2×10-6 or 2×10-8 ms-1 at 350, 400, 440 and 480 °C on flat tapered specimens of Type 316L austenitic stainless steel. The tapered shape allows the determination of crack initiation over a range of stresses and strains simultaneously on one specimen and therefore the threshold stress value was obtained. The environment was 6 times more oxidizing than the dissociation pressure of NiO. The acquired mechanical properties are summarized and threshold stresses for EAC crack initiation are evaluated.

Uneingeschränkter Zugang

Simulation of boronizing kinetics of ASTM A36 steel with the alternative kinetic model and the integral method

Online veröffentlicht: 12 Jun 2021
Seitenbereich: 33 - 39

Zusammenfassung

Abstract

In this study, two different mathematical models have been proposed for estimating the diffusivities of boron in the Fe2B layer on ASTM A36 steel in the range of 1173 to 1273 K with exposure times of 2 to 8 h. The boride incubation period required for the formation of such a layer was constant regardless of the boriding conditions. In both approaches, the boron diffusivity in the iron phase was considered in an unsaturated matrix. The first approach was derived from the mass balance equation at the (Fe2B/substrate) interface while the second approach employed the integral diffusion model. The calculated values of boron activation energies for ASTM A36 steel were found to be very comparable for the two approaches (161.65 and 160.96 and kJ mol-1). Afterwards, these values of activation energy were confronted with the results from the literature. Experimental validation of these two approaches has been done by comparing the experimental value of Fe2B layer thickness measured at 1123 K for 2.5 h with the simulated values. Finally, the predicted values of Fe2B layer thickness were in line with the experimental measurement.

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