Ti-6 Al-4 V-Si3 N4 composites were effectively fabricated by spark plasma sintering(SPS) technique. The addition of Si_3 N_4 on Ti-6 AI-4 V was varied from 5% to 15%(wt fraction). The effect of Si_3 N_4 addition on th...Ti-6 Al-4 V-Si3 N4 composites were effectively fabricated by spark plasma sintering(SPS) technique. The addition of Si_3 N_4 on Ti-6 AI-4 V was varied from 5% to 15%(wt fraction). The effect of Si_3 N_4 addition on the densification, microstructure, and microhardness and corrosion behaviour of Ti-6 Al-4 V was investigated.An increase in microhardness value was recorded from 325.46 HV_(0.1) to 585.73 HV_(0.1). X-ray diffraction(XRD) analysis showed that the intensity of diffraction peaks of Si3 N4 phase in the composites increased.The sintered Ti-6 Al-4 V reinforced with Si_3 N_4 compacts revealed the non-existence of intermediate phases, such as TiSi_2(titanium silicide) which was expected. SEM analysis of the spark plasma sintered composites revealed a and β phase microstructures in Ti-6 Al-4 V with uniform distribution of Si3 N4 particulates in the matrix. The corrosion resistance property of the material was improved by the addition of Si_3 N_4 from 0.986629 mm/year to 0.030547 mm/year.展开更多
This work considered the influence of Cr3 C2 particle loading on microstructure and mechanical properties of Zn-SiC-Cr3 C2 nanocomposite produced via electrocodeposition are investigated. The surface nature of the nan...This work considered the influence of Cr3 C2 particle loading on microstructure and mechanical properties of Zn-SiC-Cr3 C2 nanocomposite produced via electrocodeposition are investigated. The surface nature of the nanocomposite coatings were characterized using scanning electron microscope(SEM)coupled with the energy dispersive spectrometer(EDS). Abrasive wear behaviour and hardness property of Zn-SiC-Cr3 C2 nanocomposite produced were investigated using CERT UMT-2 multi-functional tribological tester and Dura Scan hardness tester. The corrosion property was evaluated through linear polarization approach. The result showed that the coatings exhibited good stability and Cr_3 C_2 nanocomposite loading significantly improved the micro structural performance, hardness property,wear resistance as well as corrosion resistance of the coatings.展开更多
The effect of egg shell powder(ES) as an environmental friendly inhibitor was studied for its corrosion inhibitive tendency on N08904 austenitic stainless steel in simulated saline(3.5% NaCl) solution using potentiody...The effect of egg shell powder(ES) as an environmental friendly inhibitor was studied for its corrosion inhibitive tendency on N08904 austenitic stainless steel in simulated saline(3.5% NaCl) solution using potentiodynamic polarization, weight loss, and SEM/EDX at room temperature. The experimental data explained the effective performance of ES with values of 57%-100% inhibition efficiency, at 2 g-10 g inhibitor concentration from weight loss tests due to the inhibition of stainless steel. The electrochemical action was as a result of the ionized particles which inhibit the compound influencing the redox reaction mechanism causing surface corrosion. ES's best performance was achieved when 6 g of the inhibitor concentration was added to the saline medium. Corrosion rate value decreased progressively with the presence of inhibitor because of anions adsorption at the interface of the metal film. Corrosion potential(Ecorr) value was found to decrease from-0.3991 V to-0.3447 V in the presence of inhibitor at 2 g concentration, decreasing gradually to-0.2048 at 6 g inhibitor concentration. The compounds identified in the ES completely adsorbed onto the surface of stainless steel as observed from the EDX analysis. The ES adsorption on stainless steel surface obeyed Langmuir adsorption isotherm. A corroded morphology with pits was observed in the SEM results without ES which contrast the images obtained with the presence of ES.展开更多
The major engineering challenge of materials in defence technologies is the vulnerability of based metals to structural and wears deformation in service. In this paper, structural formation, mechanical and thermal sta...The major engineering challenge of materials in defence technologies is the vulnerability of based metals to structural and wears deformation in service. In this paper, structural formation, mechanical and thermal stability behavior of developed composite coating of Zn-30 Al-7%Ti/Sn chloride bath and Zn-30 Al-7%Ti/Sn sulphate bath was investigated and compared to provide mitigation against failure. The thermal ageing property was done for 2 h at 600C via isothermal furnace. The structural, interfacial effect and stability behaviors of the co-deposited alloys were evaluated using scanning electron microscope equipped with energy dispersive spectrometer(SEM/EDS), atomic force microscope(AFM) and Xray diffractometer(XRD). The hardness and wear properties of the deposited coatings were examined with diamond base micro-hardness tester and reciprocating sliding tester respectively. The result shows that Zn-30 Al-7%Ti/Sn sulphate co-deposition contributed to increase hardness and wear resistance than Zn-30 Al-7%Ti/Sn chloride bath alloy. The stable crystal growth and significant performance of Zn-30 Al-7%Ti/Sn sulphate are link to the intermetallic phase hybrid of Zn Al, Zn4 Ti Al2, Zn3 Al Ti. Besides, it was observed that Zn-30 Al-7%Ti/Sn sulphate has excellent thermomechanical stability at harsh temperature,due to the deposition of Sn/Ti on steel; leading to formation of super-hard interface. However, it was established that co-deposition of mild steel with Zn-30 Al-7%Ti/Sn in sulphate bath significantly improved the structural and wear performance. It was shown that the hardness and wear of the developed composite Zn-30 Al-7%Ti/Sn is increased by about 80% compared to as received sample and about 25% compared with Zn-30 Al-7%Ti/Sn chloride coating developed. The improvement was proved to be an interference of zinc-composite growth. Thus, this work shows that sulphate induced Zn-30 Al-7%Ti/Sn via generation of controllable process parameter can provide significant improvements in thin film coating for wear mitigation and structural improvement in defence application.展开更多
Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in...Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.展开更多
Titanium has found extensive use in various engineering applications due to its attractive physical,mechanical, and chemical characteristics. However, titanium has relatively low hardness for use as an armour material...Titanium has found extensive use in various engineering applications due to its attractive physical,mechanical, and chemical characteristics. However, titanium has relatively low hardness for use as an armour material. ZrB2 was incorporated to the Ti matrix to form a Ti-based binary composites. In this study, powder metallurgy techniques were employed to disperse the ceramic particulates throughout the matrix material then consolidated through spark plasma sintering. The composites were densified at1300 ℃, pressure of 50 MPa, and holding time of 5 min. The microstructure and phase analysis of the sintered composites was carried out using SEM and XRD, while the hardness was determined using Vickers' microhardness tester. The SEM and XRD results confirmed the presence of the TiB whiskers which renowned with the improving the hardness of titanium. The hardness of the composite with 10 wt% ZrB_2 showed the highest hardness compared to that obtained for the 5 and 15 wt% ZrB_2 composites which was 495 and 571 Hv respectively.展开更多
Multifunctional nano composite coatings of Zn-TiO_2-WO_3 were deposited electrolytically on mild steel(MS) from Zn bath, having Zn^(2+) ions and uniform dispersion of TiO_2 and WO_3 nano particulates. The electrical, ...Multifunctional nano composite coatings of Zn-TiO_2-WO_3 were deposited electrolytically on mild steel(MS) from Zn bath, having Zn^(2+) ions and uniform dispersion of TiO_2 and WO_3 nano particulates. The electrical, optical and corrosion resistance characteristics of the electrocodeposited coatings were assessed by Keithley 2400 Series Source meter with Multimeters, Newport Solar Simulator and a PGSTAT30 Autolab potentiostat respectively. The morphological characteristics of the composite coatings were characterized by scanning electron microscope(SEM) equipped with energy dispersive spectrometer(EDS). The result revealed that the electrocodeposits showed good stability and Zn-TiO_2-WO_3 nanocomposite deposits displayed enhanced microstructural qualities, good electrical conductivity and exhibited enriched corrosion resistance.展开更多
Despite the massive usages of low carbon steel in automobile for engineering components, its corrosion and high friction coefficient in aggressive environment make it limited in service. This paper is aimed at modifyi...Despite the massive usages of low carbon steel in automobile for engineering components, its corrosion and high friction coefficient in aggressive environment make it limited in service. This paper is aimed at modifying low carbon steel structural component with thin film composite for enhanced mechanical and corrosion properties. The steel structure was electrodeposited with Zn-V_2 O_5 and embedded with varied NbO_2 weight concentration of 6-12 wt % based electrolyte. Scanning electron microscope(SEM) and high optical microscope was used to study the microstructural evolution of the fabricated coatings. The thermal stability of the fabricated coatings was studied in an isothermal furnace at 300 ℃ and 600 ℃ and further characterized using a high tech optical microscope. Potentiodynamic polarization technique was used to investigate the corrosion behavior of the composites in 3.65% NaCl. From the result, the effect of NbO_2 on Zn-V_2 O_5-NbO_2 was massive with improved crystal grain within the coatings lattices. The coating possesses strong metallurgical bonding and good corrosion resistance properties of about 0.315 mm/yr corrosion rate compare to 4.1 mm/yr of as-received sample. No doubt the impact of thermal shock on the resilient characteristics of the composite coating was moderate owing to the stable adherent properties of the deposited coatings.展开更多
The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic p...The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic polarization test, mass loss techniques and potential measurements. The results show that the organic derivative is highly effective with a maximum inhibition efficiency of 70.22% from mass loss analysis, while 74.2% is obtained from polarization tests. Observation of the scanning electron micrographs shows the absence of corrosion products due to electrochemical influence of TTD on the surface morphology of the steel. X-ray diffractometry reveals the absence of phase compounds and complexes on the steel samples after exposure. TTD adsorption on the steel surface obeys the Langmuir, Frumkin and Freundlich adsorption isotherms. Corrosion thermodynamic calculations reveal the inhibition mechanism occurs through chemisorption process and results from statistical analysis depict the strong influence of inhibitor concentration on the electrochemical performance of the TTD.展开更多
The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the applicati...The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of load.The experiment was conducted varying the mass concentration of silicon nitride(Si3 N4)between 7 and 13 gat cell voltage of 0.3 and 0.5 V,at constant temperature of 45℃.The morphologies of the coated surfaces were characterized using high resolution Nikon Optical Microscope and Scanning Electron Microscope(SEM)revealing that the particles of the Zn-Si3 N4 were homogeneously dispersed.The corrosion behaviour was studied using potentiodynamic polarization technique in 3.65%NaCl solution and the microhardness was examined using Brinell hardness testing technique.The result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year,maximum coating efficiency of 98.9%,maximum polarization resistance of 1555.3 Ω and a very low current density of 9.33 × 10-6A/cm2.The negative shift in the Ecorr revealed the cathodic protective nature of the coating.The microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the0.5 Zn-13 Si3 N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated Si3 N4 particles.展开更多
Wastewater effluents containing phosphorus and nitrogen are major contributors to a variety of water pollution.The present study is therefore aimed at investigating the phosphate and nitrate removal efficiency of thre...Wastewater effluents containing phosphorus and nitrogen are major contributors to a variety of water pollution.The present study is therefore aimed at investigating the phosphate and nitrate removal efficiency of three wastewater protozoa(Aspidisca, Trachelophyllum and Peranema) in a laboratory-scale water treatment system.The system was made of two separate reactors(aerated and non-aerated) and展开更多
基金financial support from National Research Foundation(NRF), Pretoria, South Africa
文摘Ti-6 Al-4 V-Si3 N4 composites were effectively fabricated by spark plasma sintering(SPS) technique. The addition of Si_3 N_4 on Ti-6 AI-4 V was varied from 5% to 15%(wt fraction). The effect of Si_3 N_4 addition on the densification, microstructure, and microhardness and corrosion behaviour of Ti-6 Al-4 V was investigated.An increase in microhardness value was recorded from 325.46 HV_(0.1) to 585.73 HV_(0.1). X-ray diffraction(XRD) analysis showed that the intensity of diffraction peaks of Si3 N4 phase in the composites increased.The sintered Ti-6 Al-4 V reinforced with Si_3 N_4 compacts revealed the non-existence of intermediate phases, such as TiSi_2(titanium silicide) which was expected. SEM analysis of the spark plasma sintered composites revealed a and β phase microstructures in Ti-6 Al-4 V with uniform distribution of Si3 N4 particulates in the matrix. The corrosion resistance property of the material was improved by the addition of Si_3 N_4 from 0.986629 mm/year to 0.030547 mm/year.
基金National Research FoundationSurface Engineering Research Centre (SERC)+1 种基金Tshwane University of Technology,Pretoria,South Africa were acknowledge for their supportCovenant University Centre for Research Innovation and Discovery (CUCRID) Ota, Nigeria for the provision of financial support
文摘This work considered the influence of Cr3 C2 particle loading on microstructure and mechanical properties of Zn-SiC-Cr3 C2 nanocomposite produced via electrocodeposition are investigated. The surface nature of the nanocomposite coatings were characterized using scanning electron microscope(SEM)coupled with the energy dispersive spectrometer(EDS). Abrasive wear behaviour and hardness property of Zn-SiC-Cr3 C2 nanocomposite produced were investigated using CERT UMT-2 multi-functional tribological tester and Dura Scan hardness tester. The corrosion property was evaluated through linear polarization approach. The result showed that the coatings exhibited good stability and Cr_3 C_2 nanocomposite loading significantly improved the micro structural performance, hardness property,wear resistance as well as corrosion resistance of the coatings.
文摘The effect of egg shell powder(ES) as an environmental friendly inhibitor was studied for its corrosion inhibitive tendency on N08904 austenitic stainless steel in simulated saline(3.5% NaCl) solution using potentiodynamic polarization, weight loss, and SEM/EDX at room temperature. The experimental data explained the effective performance of ES with values of 57%-100% inhibition efficiency, at 2 g-10 g inhibitor concentration from weight loss tests due to the inhibition of stainless steel. The electrochemical action was as a result of the ionized particles which inhibit the compound influencing the redox reaction mechanism causing surface corrosion. ES's best performance was achieved when 6 g of the inhibitor concentration was added to the saline medium. Corrosion rate value decreased progressively with the presence of inhibitor because of anions adsorption at the interface of the metal film. Corrosion potential(Ecorr) value was found to decrease from-0.3991 V to-0.3447 V in the presence of inhibitor at 2 g concentration, decreasing gradually to-0.2048 at 6 g inhibitor concentration. The compounds identified in the ES completely adsorbed onto the surface of stainless steel as observed from the EDX analysis. The ES adsorption on stainless steel surface obeyed Langmuir adsorption isotherm. A corroded morphology with pits was observed in the SEM results without ES which contrast the images obtained with the presence of ES.
基金supported financially by the National Research Foundationsupport by Surface Engineering Research Centre (SERC) Tshwane University of Technology,PretoriaThe funding received from Covenant University for open access publication
文摘The major engineering challenge of materials in defence technologies is the vulnerability of based metals to structural and wears deformation in service. In this paper, structural formation, mechanical and thermal stability behavior of developed composite coating of Zn-30 Al-7%Ti/Sn chloride bath and Zn-30 Al-7%Ti/Sn sulphate bath was investigated and compared to provide mitigation against failure. The thermal ageing property was done for 2 h at 600C via isothermal furnace. The structural, interfacial effect and stability behaviors of the co-deposited alloys were evaluated using scanning electron microscope equipped with energy dispersive spectrometer(SEM/EDS), atomic force microscope(AFM) and Xray diffractometer(XRD). The hardness and wear properties of the deposited coatings were examined with diamond base micro-hardness tester and reciprocating sliding tester respectively. The result shows that Zn-30 Al-7%Ti/Sn sulphate co-deposition contributed to increase hardness and wear resistance than Zn-30 Al-7%Ti/Sn chloride bath alloy. The stable crystal growth and significant performance of Zn-30 Al-7%Ti/Sn sulphate are link to the intermetallic phase hybrid of Zn Al, Zn4 Ti Al2, Zn3 Al Ti. Besides, it was observed that Zn-30 Al-7%Ti/Sn sulphate has excellent thermomechanical stability at harsh temperature,due to the deposition of Sn/Ti on steel; leading to formation of super-hard interface. However, it was established that co-deposition of mild steel with Zn-30 Al-7%Ti/Sn in sulphate bath significantly improved the structural and wear performance. It was shown that the hardness and wear of the developed composite Zn-30 Al-7%Ti/Sn is increased by about 80% compared to as received sample and about 25% compared with Zn-30 Al-7%Ti/Sn chloride coating developed. The improvement was proved to be an interference of zinc-composite growth. Thus, this work shows that sulphate induced Zn-30 Al-7%Ti/Sn via generation of controllable process parameter can provide significant improvements in thin film coating for wear mitigation and structural improvement in defence application.
文摘Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.
基金supported financially by the National Research Foundationthe support from the the Tshwane University of Technology, Pretoria, South Africa which helped to accomplish this work
文摘Titanium has found extensive use in various engineering applications due to its attractive physical,mechanical, and chemical characteristics. However, titanium has relatively low hardness for use as an armour material. ZrB2 was incorporated to the Ti matrix to form a Ti-based binary composites. In this study, powder metallurgy techniques were employed to disperse the ceramic particulates throughout the matrix material then consolidated through spark plasma sintering. The composites were densified at1300 ℃, pressure of 50 MPa, and holding time of 5 min. The microstructure and phase analysis of the sintered composites was carried out using SEM and XRD, while the hardness was determined using Vickers' microhardness tester. The SEM and XRD results confirmed the presence of the TiB whiskers which renowned with the improving the hardness of titanium. The hardness of the composite with 10 wt% ZrB_2 showed the highest hardness compared to that obtained for the 5 and 15 wt% ZrB_2 composites which was 495 and 571 Hv respectively.
基金financial support by National Research Foundation
文摘Multifunctional nano composite coatings of Zn-TiO_2-WO_3 were deposited electrolytically on mild steel(MS) from Zn bath, having Zn^(2+) ions and uniform dispersion of TiO_2 and WO_3 nano particulates. The electrical, optical and corrosion resistance characteristics of the electrocodeposited coatings were assessed by Keithley 2400 Series Source meter with Multimeters, Newport Solar Simulator and a PGSTAT30 Autolab potentiostat respectively. The morphological characteristics of the composite coatings were characterized by scanning electron microscope(SEM) equipped with energy dispersive spectrometer(EDS). The result revealed that the electrocodeposits showed good stability and Zn-TiO_2-WO_3 nanocomposite deposits displayed enhanced microstructural qualities, good electrical conductivity and exhibited enriched corrosion resistance.
文摘Despite the massive usages of low carbon steel in automobile for engineering components, its corrosion and high friction coefficient in aggressive environment make it limited in service. This paper is aimed at modifying low carbon steel structural component with thin film composite for enhanced mechanical and corrosion properties. The steel structure was electrodeposited with Zn-V_2 O_5 and embedded with varied NbO_2 weight concentration of 6-12 wt % based electrolyte. Scanning electron microscope(SEM) and high optical microscope was used to study the microstructural evolution of the fabricated coatings. The thermal stability of the fabricated coatings was studied in an isothermal furnace at 300 ℃ and 600 ℃ and further characterized using a high tech optical microscope. Potentiodynamic polarization technique was used to investigate the corrosion behavior of the composites in 3.65% NaCl. From the result, the effect of NbO_2 on Zn-V_2 O_5-NbO_2 was massive with improved crystal grain within the coatings lattices. The coating possesses strong metallurgical bonding and good corrosion resistance properties of about 0.315 mm/yr corrosion rate compare to 4.1 mm/yr of as-received sample. No doubt the impact of thermal shock on the resilient characteristics of the composite coating was moderate owing to the stable adherent properties of the deposited coatings.
文摘The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic polarization test, mass loss techniques and potential measurements. The results show that the organic derivative is highly effective with a maximum inhibition efficiency of 70.22% from mass loss analysis, while 74.2% is obtained from polarization tests. Observation of the scanning electron micrographs shows the absence of corrosion products due to electrochemical influence of TTD on the surface morphology of the steel. X-ray diffractometry reveals the absence of phase compounds and complexes on the steel samples after exposure. TTD adsorption on the steel surface obeys the Langmuir, Frumkin and Freundlich adsorption isotherms. Corrosion thermodynamic calculations reveal the inhibition mechanism occurs through chemisorption process and results from statistical analysis depict the strong influence of inhibitor concentration on the electrochemical performance of the TTD.
文摘The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of load.The experiment was conducted varying the mass concentration of silicon nitride(Si3 N4)between 7 and 13 gat cell voltage of 0.3 and 0.5 V,at constant temperature of 45℃.The morphologies of the coated surfaces were characterized using high resolution Nikon Optical Microscope and Scanning Electron Microscope(SEM)revealing that the particles of the Zn-Si3 N4 were homogeneously dispersed.The corrosion behaviour was studied using potentiodynamic polarization technique in 3.65%NaCl solution and the microhardness was examined using Brinell hardness testing technique.The result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year,maximum coating efficiency of 98.9%,maximum polarization resistance of 1555.3 Ω and a very low current density of 9.33 × 10-6A/cm2.The negative shift in the Ecorr revealed the cathodic protective nature of the coating.The microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the0.5 Zn-13 Si3 N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated Si3 N4 particles.
文摘Wastewater effluents containing phosphorus and nitrogen are major contributors to a variety of water pollution.The present study is therefore aimed at investigating the phosphate and nitrate removal efficiency of three wastewater protozoa(Aspidisca, Trachelophyllum and Peranema) in a laboratory-scale water treatment system.The system was made of two separate reactors(aerated and non-aerated) and
