yuhang guo - Academia.edu (original) (raw)

Papers by yuhang guo

Materials, 2018

Through a coordinate transformation approach, crystal orientation dependences of elastic and piez... more Through a coordinate transformation approach, crystal orientation dependences of elastic and piezoelectric properties at room temperature have been investigated in a three-dimensional space for rhombohedral bismuth ferrite (BiFeO3). Elastic constants (stiffnesses) c11′, c12′, c13′ and piezoelectric constants d15′, d31′, d33′ along arbitrary orientations were obtained based on crystalline asymmetry characteristics of 3m point group BiFeO3. Parameters along specific orientations obtaining the largest values were presented. The max c11′ = 213 × 109 N/m2 could be achieved in planes with ϕ = 0° and 90°. The max c12′ = c13′ = 132.2 × 109 N/m2 could be achieved along directions at θ = 13° and θ = 77° inside three mirror planes, respectively. The max d15′ = 27.6 × 10−12 C/N and the max d31′ = 12.67 × 10−12 C/N could be both obtained along directions at θ = 69° inside mirror planes. The max d33′ = 18 × 10−12 C/N could be obtained at θ = 0°, along the spontaneous polarization axis. By adoptin...

International Journal of Electrochemical Science, 2016

The inhibition effect of a Schiff base N′-bis (2-pyridylmethylidene)-1,2-diiminoethane (BPMDE) on... more The inhibition effect of a Schiff base N′-bis (2-pyridylmethylidene)-1,2-diiminoethane (BPMDE) on AZ31 magnesium alloy was studied in this work. Results showed the BPMDE acts as an effective inhibitor for magnesium in 0.01 M HCl. Potentiodynamic polarization characterization revealed the BPMDE inhibits both anodic and cathodic reactions, indicating the BPMDE acts as a mixed-type corrosion inhibitor behavior. Due to the increasing of adsorption of BPMDE on magnesium alloy surface, the charge transfer resistance consequently increased while the double layer capacitance declined. Moreover, the adsorption of BPMDE on the AZ31 magnesium alloy surface obeys the Langmuir isotherm.

Materials, 2021

We prepared three kinds of Ni based alloy cladding coatings on 316L stainless steel at different ... more We prepared three kinds of Ni based alloy cladding coatings on 316L stainless steel at different power levels. The microstructure of the cladding layer was observed and analyzed by XRD, metallographic microscope, and SEM. The hardness of the cladding layer was measured, and the wear resistance of it was tested by a friction instrument. The results show that the effect of laser cladding is good, and it has good metallurgical bonding with the substrate. Different microstructures such as dendritic and equiaxed grains can be observed in the cladding layer. With the increase in laser power, more equiaxed and columnar dendrites can be observed. The phase composition of the cladding layer is mainly composed of γ–Ni solid solution and some intermetallic compounds such as Ni3B, Cr5B3, and Ni17Si3. The results of EDS show that there are some differences in the distribution of C and Si between dendrites. The hardness of the cladding layer is about 600 HV0.2, which is about three times of the s...

Three kinds of Ni based alloy cladding coatings were prepared on 316L stainless steel at differen... more Three kinds of Ni based alloy cladding coatings were prepared on 316L stainless steel at different power. The microstructure of the cladding layer was observed and analyzed by XRD, metallographic microscope and SEM. The hardness of the cladding layer was measured, and the wear resistance of the cladding layer was tested by friction instrument. The results show that the effect of laser cladding is good and the cladding layer has a good metallurgical bonding with the substrate. Different microstructures such as dendritic and equiaxed grains can be observed in the cladding layer. With the increase of laser power, more equiaxed and columnar dendrites can be observed. The phase composition of the cladding layer is mainly composed of γ - Ni solid solution and some intermetallic compounds such as Ni3B, Cr5B3 and Ni17Si3. The results of EDS show that there are some differences in the distribution of C and Si between dendrites. The hardness of the cladding layer is about 600 HV0.2, which is ...

Metals

In this study, single-layer and three-layer nickel-based coatings were fabricated on 316L SS by l... more In this study, single-layer and three-layer nickel-based coatings were fabricated on 316L SS by laser additive manufacturing. The phase characterization, microstructure observation, and microhardness analysis of the coatings were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), and microhardness tester. And the wear resistance of the coatings was analyzed through dry sliding friction and wear test. The results show that the cross-section microstructure of the three-layer nickel-based coating is different from that of the single-layer one under the influence of heat accumulation; the dendrite structure in the central region of the former is equiaxial dendrite, while that of the latter still remains large columnar dendrites. The existence of solid solution phase γ-(Fe, Ni) and hard phases of Ni17Si3, Cr5B3, Ni3B in the coating significantly improve the wear resistance of the coating, and the microhardness is nearly 2.5 times higher than that of the substrate...

Materials

In this work, the Mg-3Sn-2Al-1Zn (TAZ321, wt. %) alloy with excellent high temperature resistance... more In this work, the Mg-3Sn-2Al-1Zn (TAZ321, wt. %) alloy with excellent high temperature resistance was compressed using a Gleeble-3500 thermo-mechanical simulator at a wide temperature and the strain rate range. The kinetics analyses showed that the dominant deformation mechanism was likely caused by the cross slipping of dislocations. A constitutive equation which expressed the relationship between the flow stress, deformation temperature, and strain rate was established, and the average activation energy Q was calculated to be 172.1 kJ/mol. In order to delineate the stability and instability working domains, as well as obtain the optimum hot working parameters of the alloy, the hot processing maps in accordance with Prassad’s criterion are constructed at the true strain of 0.2, 0.4, 0.6, and 0.8, respectively. Based on the hot processing map and microstructure observation, the optimum hot working parameter was determined to be 350 °C/1 s−1. The continuous fine dynamic recrystalliza...

Journal of Alloys and Compounds

Abstract Core-shell ternary composite composed of a Sn/SnO 2 nanoparticle core and amorphous carb... more Abstract Core-shell ternary composite composed of a Sn/SnO 2 nanoparticle core and amorphous carbon shell were successfully prepared by a simple hydrothermal route. Crystal phase structure, composition, morphology of the final product were characterized by the transmission electron microcopy, X-ray photoelectron (XPS) and Raman technique. This ternary composite presented excellent electromagnetic absorption properties if applied to treat the electromagnetic interference issue (EMI). The optimal effective absorption frequency covered 6.8 GHz with a thin coating thickness, which was quite better than Sn@C and SnO 2 @C binary composite. The improvement electromagnetic absorption mechanism was attributed to the moderate permittivity value which ensure the balanced impedance matching and dielectric loss ability. Besides, the probably interface polarization effect was proposed in this research which benefited to the attenuate electromagnetic wave.

Materials, 2018

Through a coordinate transformation approach, crystal orientation dependences of elastic and piez... more Through a coordinate transformation approach, crystal orientation dependences of elastic and piezoelectric properties at room temperature have been investigated in a three-dimensional space for rhombohedral bismuth ferrite (BiFeO3). Elastic constants (stiffnesses) c11′, c12′, c13′ and piezoelectric constants d15′, d31′, d33′ along arbitrary orientations were obtained based on crystalline asymmetry characteristics of 3m point group BiFeO3. Parameters along specific orientations obtaining the largest values were presented. The max c11′ = 213 × 109 N/m2 could be achieved in planes with ϕ = 0° and 90°. The max c12′ = c13′ = 132.2 × 109 N/m2 could be achieved along directions at θ = 13° and θ = 77° inside three mirror planes, respectively. The max d15′ = 27.6 × 10−12 C/N and the max d31′ = 12.67 × 10−12 C/N could be both obtained along directions at θ = 69° inside mirror planes. The max d33′ = 18 × 10−12 C/N could be obtained at θ = 0°, along the spontaneous polarization axis. By adoptin...

International Journal of Electrochemical Science, 2016

The inhibition effect of a Schiff base N′-bis (2-pyridylmethylidene)-1,2-diiminoethane (BPMDE) on... more The inhibition effect of a Schiff base N′-bis (2-pyridylmethylidene)-1,2-diiminoethane (BPMDE) on AZ31 magnesium alloy was studied in this work. Results showed the BPMDE acts as an effective inhibitor for magnesium in 0.01 M HCl. Potentiodynamic polarization characterization revealed the BPMDE inhibits both anodic and cathodic reactions, indicating the BPMDE acts as a mixed-type corrosion inhibitor behavior. Due to the increasing of adsorption of BPMDE on magnesium alloy surface, the charge transfer resistance consequently increased while the double layer capacitance declined. Moreover, the adsorption of BPMDE on the AZ31 magnesium alloy surface obeys the Langmuir isotherm.

Materials, 2021

We prepared three kinds of Ni based alloy cladding coatings on 316L stainless steel at different ... more We prepared three kinds of Ni based alloy cladding coatings on 316L stainless steel at different power levels. The microstructure of the cladding layer was observed and analyzed by XRD, metallographic microscope, and SEM. The hardness of the cladding layer was measured, and the wear resistance of it was tested by a friction instrument. The results show that the effect of laser cladding is good, and it has good metallurgical bonding with the substrate. Different microstructures such as dendritic and equiaxed grains can be observed in the cladding layer. With the increase in laser power, more equiaxed and columnar dendrites can be observed. The phase composition of the cladding layer is mainly composed of γ–Ni solid solution and some intermetallic compounds such as Ni3B, Cr5B3, and Ni17Si3. The results of EDS show that there are some differences in the distribution of C and Si between dendrites. The hardness of the cladding layer is about 600 HV0.2, which is about three times of the s...

Three kinds of Ni based alloy cladding coatings were prepared on 316L stainless steel at differen... more Three kinds of Ni based alloy cladding coatings were prepared on 316L stainless steel at different power. The microstructure of the cladding layer was observed and analyzed by XRD, metallographic microscope and SEM. The hardness of the cladding layer was measured, and the wear resistance of the cladding layer was tested by friction instrument. The results show that the effect of laser cladding is good and the cladding layer has a good metallurgical bonding with the substrate. Different microstructures such as dendritic and equiaxed grains can be observed in the cladding layer. With the increase of laser power, more equiaxed and columnar dendrites can be observed. The phase composition of the cladding layer is mainly composed of γ - Ni solid solution and some intermetallic compounds such as Ni3B, Cr5B3 and Ni17Si3. The results of EDS show that there are some differences in the distribution of C and Si between dendrites. The hardness of the cladding layer is about 600 HV0.2, which is ...

Metals

In this study, single-layer and three-layer nickel-based coatings were fabricated on 316L SS by l... more In this study, single-layer and three-layer nickel-based coatings were fabricated on 316L SS by laser additive manufacturing. The phase characterization, microstructure observation, and microhardness analysis of the coatings were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), and microhardness tester. And the wear resistance of the coatings was analyzed through dry sliding friction and wear test. The results show that the cross-section microstructure of the three-layer nickel-based coating is different from that of the single-layer one under the influence of heat accumulation; the dendrite structure in the central region of the former is equiaxial dendrite, while that of the latter still remains large columnar dendrites. The existence of solid solution phase γ-(Fe, Ni) and hard phases of Ni17Si3, Cr5B3, Ni3B in the coating significantly improve the wear resistance of the coating, and the microhardness is nearly 2.5 times higher than that of the substrate...

Materials

In this work, the Mg-3Sn-2Al-1Zn (TAZ321, wt. %) alloy with excellent high temperature resistance... more In this work, the Mg-3Sn-2Al-1Zn (TAZ321, wt. %) alloy with excellent high temperature resistance was compressed using a Gleeble-3500 thermo-mechanical simulator at a wide temperature and the strain rate range. The kinetics analyses showed that the dominant deformation mechanism was likely caused by the cross slipping of dislocations. A constitutive equation which expressed the relationship between the flow stress, deformation temperature, and strain rate was established, and the average activation energy Q was calculated to be 172.1 kJ/mol. In order to delineate the stability and instability working domains, as well as obtain the optimum hot working parameters of the alloy, the hot processing maps in accordance with Prassad’s criterion are constructed at the true strain of 0.2, 0.4, 0.6, and 0.8, respectively. Based on the hot processing map and microstructure observation, the optimum hot working parameter was determined to be 350 °C/1 s−1. The continuous fine dynamic recrystalliza...

Journal of Alloys and Compounds

Abstract Core-shell ternary composite composed of a Sn/SnO 2 nanoparticle core and amorphous carb... more Abstract Core-shell ternary composite composed of a Sn/SnO 2 nanoparticle core and amorphous carbon shell were successfully prepared by a simple hydrothermal route. Crystal phase structure, composition, morphology of the final product were characterized by the transmission electron microcopy, X-ray photoelectron (XPS) and Raman technique. This ternary composite presented excellent electromagnetic absorption properties if applied to treat the electromagnetic interference issue (EMI). The optimal effective absorption frequency covered 6.8 GHz with a thin coating thickness, which was quite better than Sn@C and SnO 2 @C binary composite. The improvement electromagnetic absorption mechanism was attributed to the moderate permittivity value which ensure the balanced impedance matching and dielectric loss ability. Besides, the probably interface polarization effect was proposed in this research which benefited to the attenuate electromagnetic wave.