Air nanobubbles(A-NBs)were used to inhibit the brass corrosion in circulating cooling water for the first time in the study.The results of mass loss method and electrochemical method showed that A-NBs had the obvious ...Air nanobubbles(A-NBs)were used to inhibit the brass corrosion in circulating cooling water for the first time in the study.The results of mass loss method and electrochemical method showed that A-NBs had the obvious corrosion inhibition effect.The inhibition rate reached 52%at 35℃.The impedance and surface characterization results of corrosion samples indicated that the corrosion inhibition mechanisms of A-NBs mainly included adsorption of corrosion ions,promoting the formation of the passivation film on metal surface and the formation of the bubble layer and scale film on metal surface.A-NBs are potential excellent corrosion inhibitors.展开更多
In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear chara...In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear characteristics was investigated. The friction-wearexperiment was carried out on the block-on-ring tribometer MM 200. The worn surfaces of the frictionpair consisting of the composite materials and grey cast iron HT 200 under dry sliding frictionwere examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) anddifferential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showedthat the friction coefficient and the wear loss of the composite material increase obviously withthe increase of cast iron debris content, but decrease obviously with the increase of graphitepowder content, and increase a little when the mass fraction of brass fiber was over 19 percent, andthe orientation of brass fiber has obvious influence on friction-wear property. When the massfraction of organic adhesion agent was about 10-11 percent, the composite materials have anexcellent friction-wear performance. The friction heat can pyrolyze organic ingredient in wornsurface layer.展开更多
Two kinds of silver based medium temperature brazing filler metals(45AgCuZnSn and 60AgCuSn) were selected to braze and seal brass flange pipe and copper pipe by high frequency heating brazing. In this paper, the quali...Two kinds of silver based medium temperature brazing filler metals(45AgCuZnSn and 60AgCuSn) were selected to braze and seal brass flange pipe and copper pipe by high frequency heating brazing. In this paper, the quality of the braze was evaluated by immersion ultrasound, and the microstructure of the brazed joint was observed by SEM and EDS. The experimental results show that the high frequency heating brazing can quickly achieve the device sealing;through the ultrasonic flaw detection image calculation, the brazed bonding rate obtained by 60AgCuSn brazing is 87%, and by 45AgCuZnSn brazing is 71%;the cross-sectional area of the brazed joint obtained by two kinds of silver based medium temperature brazing filler metals is observed, the brazed joint obtained by 45AgCuZnSn brazing has defects visual, and a large amount of Zn element gathered in the defects, there is no obvious porosity in the brazed joint by 60AgCuSn brazing,and the bonding layer is dense and coherent. Through the contrast test, the choice of 60AgCuSn alloy brazing can meet the needs of high frequency brazing of brass flange pipe and copper pipe.展开更多
Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification c...Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification corrosion of β phase continuous HMn58 2 brass is characterized by β phase volume diffusion, while that of α phase continuous HSn62 1 brass is controlled by α phase grain boundary diffusion. Apparent diffusion coefficients of zinc in both types alloys were calculated out by founding diffusion equation and boundary conditions. It was found that the value of theoretical calculation is close to that of experimentally measured, and it confirmed that Sn element inhibits dezincification of brass. The relativity between the dezincification depth and corrosion rate of different double phase brasses immersed in seawater was revealed. : Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification corrosion of β phase continuous HMn58 2 brass is characterized by β phase volume diffusion, while that of α phase continuous HSn62 1 brass is controlled by α phase grain boundary diffusion. Apparent diffusion coefficients of zinc in both types alloys were calculated out by founding diffusion equation and boundary conditions. It was found that the value of theoretical calculation is close to that of experimentally measured, and it confirmed that Sn element inhibits dezincification of brass. The relativity between the dezincification depth and corrosion rate of different double phase brasses immersed in seawater was revealed.展开更多
In a procedure for electrolytic dissolving pure copper and common brasses, the approximate electrochemical mole mass(k) of the sample was determined in accordance with the brand of the sample, a stitable electrolyte w...In a procedure for electrolytic dissolving pure copper and common brasses, the approximate electrochemical mole mass(k) of the sample was determined in accordance with the brand of the sample, a stitable electrolyte was selected to make the current efficiency equal to 100%, and then the dissolved mass of samples was calculated according to Faraday's law(m=klt).Three representative samples were sampled by the electrolytic dissolution method and the calculated dissolved amounts were equal to the values by weighing the anode.The cxperimental results of zinc and copper in the anode liquor are in agreement with certified values.展开更多
Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of t...Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass.展开更多
The susceptibility to stress corrosion cracking (SCC) of brass in an ammoniasolution with various pH values or under various applied potentials was measured at slow strain ratetests. The additive stress in the same so...The susceptibility to stress corrosion cracking (SCC) of brass in an ammoniasolution with various pH values or under various applied potentials was measured at slow strain ratetests. The additive stress in the same solution was measured using two methods. The resultsindicate that the variation of the susceptibility to SCC with pH value or with potential is in anexcellent agreement with the corrosion (passive film or dezincification layer)-induced stress. WhenpH >= 7, the corrosion-induced tensile stress and the susceptibility to SCC have maximum values andhardly change with increasing the pH value. However, when pH <7, both the corrosion-induced tensilestress and the susceptibility to SCC reduce rapidly with decreasing the pH value. Both thecorrosion-induced tensile stress and the susceptibility to SCC have maximum values at theopen-circuit potential, decrease slightly under the anodic polarization, and reduce gradually tozero under the cathodic polarization.展开更多
Four protic ionic liquids(ILs)were synthesized via a one-step method by using benzotriazole(BTA)and benzimidazole as cations,and benzenesulfonic acid and 2-naphthalenesulfonic acid(NSA)as anions.These ILs were used as...Four protic ionic liquids(ILs)were synthesized via a one-step method by using benzotriazole(BTA)and benzimidazole as cations,and benzenesulfonic acid and 2-naphthalenesulfonic acid(NSA)as anions.These ILs were used as green corrosion inhibitors for brass specimens in a nitric acid solution.The structure of the protic ILs was characterized by 1H-NMR,13C-NMR,and FT-IR spectroscopy.The effects of the IL structure,IL concentration,acid concentration,and corrosion time on the surface morphology of brass specimens and the inhibition efficiency(η%)of ILs were investigated by the weight loss method combined with SEM and EDS spectroscopy.Polarization curves and impedance spectroscopy were used to analyze the electrochemical corrosion inhibition mechanism of ILs.Results showed that IL synthesis was a proton transfer process,and the proton of the–SO3H group on NSA was deprived by BTA.IL[BTA][NSA],which had a high charge density and large conjugateπband,was the most effective inhibitor for brass corrosion.Theη%of[BTA][NSA]decreased with the increase in acid concentration and corrosion time,which showed an increment with the increase in[BTA][NSA]concentration.The higher theη%of[BTA][NSA]is,the smoother the surface of the brass specimens is,and the smaller the undistributed area of Cu element will be.Corrosion inhibiting mechanism from electrochemical analysis indicated that the addition of[BTA][NSA]increased the polarization resistance of the brass electrode significantly and suppressed both anodic and cathodic reactions.展开更多
After brass is coated with tin, heat treatment makes the coating metal Sn and the substrate metallic elements Cu and Zn diffuse with each other. This causes the coating composition to be changed and the interface to b...After brass is coated with tin, heat treatment makes the coating metal Sn and the substrate metallic elements Cu and Zn diffuse with each other. This causes the coating composition to be changed and the interface to be strengthened. The diffusion coating with a multiphase structure formed by this process has excellent properties of antifriction and wear resistance. With the aid of scanning electron microscopy, electronic probe microanalysis and X ray diffraction, the mechanism of the properties is discussed.展开更多
The Characteristic and mechanism of corrosion of brass exposed to seawater for several years, including alloys with single alpha-phase and alpha + beta phase, were investigated by means of metallograph, SEM, EDS and s...The Characteristic and mechanism of corrosion of brass exposed to seawater for several years, including alloys with single alpha-phase and alpha + beta phase, were investigated by means of metallograph, SEM, EDS and so on. It shows that severe corrosion with intergranular and dezincification characteristics occurred on the specimens of H-68A, which was single alpha-phase brass with As element addition. For the brass of HSn70-1A, which was single-phase alloy with ils and Sn additions, much better corrosion resistance could be exhibited due to the formation of Sn enrichment corrosion product film. Sn element is much easier to enrich at phase and grain boundaries than towards surface film. This would inhibit dezincification of the alpha + beta phase brass to some extent. However, it is not enough for the Sn element addition in the brass HSn62-1 with alpha + beta phase to resist dezincification corrosion getting through phase and grain boundaries of the brass. The alleging elements boundary diffusion plays an important role in the corrosion behavior of both alpha-phase and alpha + beta phase brass.展开更多
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that und...The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.展开更多
1.IntroductionSuperplasticity is not merely a specialphenomenon for certain specific alley,but isone of the intrinsic properties of metallicmaterials[1].When the internal and externalconditions are suitable,superplast...1.IntroductionSuperplasticity is not merely a specialphenomenon for certain specific alley,but isone of the intrinsic properties of metallicmaterials[1].When the internal and externalconditions are suitable,superplasticity ofmetal materials will be presented.展开更多
Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution...Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution of major alloying elements in the intelfacial layer were examined, and the tensile strength of the resultant joints was measured. Pores appeared in the weld made with Zn-15% Al flax-cored filler wire, the interracial layer mainly consisted of AlCu phase, and the specimens fractured through the weld with tensile strength of 129 MPa. When Al-12% Si flux-cored filler wire was used, Cu diffused into the weld and Al2 Cu phase formed, and the specimens fractured along the interfacial layer with tensile strength of 122 MPa.展开更多
In response to environmental guidelines, a low phosphonic multipolymer was synthesized and its corrosion inhibition efficiency to brass in synthetic water was investigated through weight loss measurements and electroc...In response to environmental guidelines, a low phosphonic multipolymer was synthesized and its corrosion inhibition efficiency to brass in synthetic water was investigated through weight loss measurements and electrochemical tests. It showed that the synthesized inhibitor decreased corrosion under the conditions tested. Potentiodynamic polarization curves indicated that the new inhibitor acted as an anodic inhibitor, reducing metal dissolution. The composition of protective films formed on the brass was studied by energy-dispersive X-ray analysis (EDX). The inhibition effects were due to the formation of a protective film of the multipolymer inhibitor on the metal surface.展开更多
Leaded brass alloys used progressively in many applications such as gas valves production owing to their excellent machinability, corrosion resistance and some other specifications. However, the production processes o...Leaded brass alloys used progressively in many applications such as gas valves production owing to their excellent machinability, corrosion resistance and some other specifications. However, the production processes of these alloys involve some problems appearing in the last activities of production as a result of cumulative defects of previous production processes. Therefore, the current investigation studies the effect of process parameters during casting, hot extrusion and cold drawing production stages of CuZn40Pb2 leaded brass alloy on the mechanical properties. Starting with casting process, two types of charges were used. The first charge consists of 100% recycles while the second contains 30% of pure materials such as Cu, Zn and Pb in addition to the recycles. For each production stage, alloy hardness, micro-hardness, ultimate tensile strength and elongation were examined. The results illustrated that high hardness values are obtained during casting process due to some impurities such as iron and the effect of cooling rate through solidification. The hardness values decrease during extrusion process and then rise again by cold drawing for the charge of 30% pure materials. Micro-hardness values for the fractured tensile test samples appeared higher than others due to work hardening effect. The best mechanical properties as ultimate tensile strength of CuZn40Pb2 alloy products are appeared into cold forming samples with the 30% pure material added.展开更多
Brass is an excellent material choice for use in most industrial and agricultural application. Brass offers much better thermal conductivity and corrosion resistance than carbon or even stainless steel. Brass is an ex...Brass is an excellent material choice for use in most industrial and agricultural application. Brass offers much better thermal conductivity and corrosion resistance than carbon or even stainless steel. Brass is an excellent material for use in both hot and cold water industrial and residential system including those carrying portable water. This study was carried out to investigate and evaluate the influence of fossil fuel like petrol, kerosene and diesel on the corrosion performance of brass. The samples were prepared for the study by cutting brass into 1 cm2 coupons and soaking them in different small plastic containers containing petrol, kerosene and diesel. The corrosion rate of each sample for a specific period of immersion (120, 240, 360, and 480, 600 and 720 hours) was determined on average of three samples exposed under the same condition and test media in different container. The finding showed that brass is resistant to corrosion after long hours of contact in chosen liquid fossil fuels. Brass has the highest corrosion rate in petrol, followed by kerosene and least in diesel. The photomicrographs of the samples after ten days of immersion also confirmed this.展开更多
Wear is a continuous process in which material is degraded with every cycle. Scientists are busy in improving the wear resistance. Approximately 75% failure in components or machine parts is due to wear. The present p...Wear is a continuous process in which material is degraded with every cycle. Scientists are busy in improving the wear resistance. Approximately 75% failure in components or machine parts is due to wear. The present paper investigates experimentally the effect of orientation and normal load on alloy of copper and zinc, i.e. Brass, and calculates weight loss due to wear. To do so, a multi-orientational pin-on-disc apparatus was designed and fabricated. Experiments were carried out under normal load 05-20 N, speed 2000 rpm. Results show that the with-increasing load weight loss increases at all angular positions. The loss in weight is maximum at zero degree (horizontal position) and minimum at ninety degree (vertical position) for a particular load. Maximum wear occurs when the test specimen is held at 0° angle and minimum wear occurs when the specimen is held at 90° angle for given applied load. The circumferential distance travel is constant for all positions and for all loads but still mass loss varies.展开更多
In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and...In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and Zener-Hillert's model,respectively.It is found that the stacking fault substructure exists just in the growth tip of fresh bainitie plate and so does the shear stress in the matrix around the tip.The measured lengthening rate of bainitic plate is not con- sistent with Trivedi's model.The thiekening process is only macroscopieally controlled by vol- ume diffusion but its nature is a shear process.展开更多
基金supported by National Natural Science Foundation of China(52170074).
文摘Air nanobubbles(A-NBs)were used to inhibit the brass corrosion in circulating cooling water for the first time in the study.The results of mass loss method and electrochemical method showed that A-NBs had the obvious corrosion inhibition effect.The inhibition rate reached 52%at 35℃.The impedance and surface characterization results of corrosion samples indicated that the corrosion inhibition mechanisms of A-NBs mainly included adsorption of corrosion ions,promoting the formation of the passivation film on metal surface and the formation of the bubble layer and scale film on metal surface.A-NBs are potential excellent corrosion inhibitors.
文摘In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear characteristics was investigated. The friction-wearexperiment was carried out on the block-on-ring tribometer MM 200. The worn surfaces of the frictionpair consisting of the composite materials and grey cast iron HT 200 under dry sliding frictionwere examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) anddifferential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showedthat the friction coefficient and the wear loss of the composite material increase obviously withthe increase of cast iron debris content, but decrease obviously with the increase of graphitepowder content, and increase a little when the mass fraction of brass fiber was over 19 percent, andthe orientation of brass fiber has obvious influence on friction-wear property. When the massfraction of organic adhesion agent was about 10-11 percent, the composite materials have anexcellent friction-wear performance. The friction heat can pyrolyze organic ingredient in wornsurface layer.
基金supported by the National Key R&D Program of China(Grant No. 2017YFB0305702)。
文摘Two kinds of silver based medium temperature brazing filler metals(45AgCuZnSn and 60AgCuSn) were selected to braze and seal brass flange pipe and copper pipe by high frequency heating brazing. In this paper, the quality of the braze was evaluated by immersion ultrasound, and the microstructure of the brazed joint was observed by SEM and EDS. The experimental results show that the high frequency heating brazing can quickly achieve the device sealing;through the ultrasonic flaw detection image calculation, the brazed bonding rate obtained by 60AgCuSn brazing is 87%, and by 45AgCuZnSn brazing is 71%;the cross-sectional area of the brazed joint obtained by two kinds of silver based medium temperature brazing filler metals is observed, the brazed joint obtained by 45AgCuZnSn brazing has defects visual, and a large amount of Zn element gathered in the defects, there is no obvious porosity in the brazed joint by 60AgCuSn brazing,and the bonding layer is dense and coherent. Through the contrast test, the choice of 60AgCuSn alloy brazing can meet the needs of high frequency brazing of brass flange pipe and copper pipe.
文摘Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification corrosion of β phase continuous HMn58 2 brass is characterized by β phase volume diffusion, while that of α phase continuous HSn62 1 brass is controlled by α phase grain boundary diffusion. Apparent diffusion coefficients of zinc in both types alloys were calculated out by founding diffusion equation and boundary conditions. It was found that the value of theoretical calculation is close to that of experimentally measured, and it confirmed that Sn element inhibits dezincification of brass. The relativity between the dezincification depth and corrosion rate of different double phase brasses immersed in seawater was revealed. : Zinc diffusion kinetics of double phase brass as they were corroded in seawater was investigated by means of metallography microscope and mathematics regression analysis. The results showed that, the dezincification corrosion of β phase continuous HMn58 2 brass is characterized by β phase volume diffusion, while that of α phase continuous HSn62 1 brass is controlled by α phase grain boundary diffusion. Apparent diffusion coefficients of zinc in both types alloys were calculated out by founding diffusion equation and boundary conditions. It was found that the value of theoretical calculation is close to that of experimentally measured, and it confirmed that Sn element inhibits dezincification of brass. The relativity between the dezincification depth and corrosion rate of different double phase brasses immersed in seawater was revealed.
文摘In a procedure for electrolytic dissolving pure copper and common brasses, the approximate electrochemical mole mass(k) of the sample was determined in accordance with the brand of the sample, a stitable electrolyte was selected to make the current efficiency equal to 100%, and then the dissolved mass of samples was calculated according to Faraday's law(m=klt).Three representative samples were sampled by the electrolytic dissolution method and the calculated dissolved amounts were equal to the values by weighing the anode.The cxperimental results of zinc and copper in the anode liquor are in agreement with certified values.
文摘Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass.
基金This project was supported by National Natural Science Foundation of China (No.50071010)and by the special Funds for the Major Stare Basic Research Projects (19990650).]
文摘The susceptibility to stress corrosion cracking (SCC) of brass in an ammoniasolution with various pH values or under various applied potentials was measured at slow strain ratetests. The additive stress in the same solution was measured using two methods. The resultsindicate that the variation of the susceptibility to SCC with pH value or with potential is in anexcellent agreement with the corrosion (passive film or dezincification layer)-induced stress. WhenpH >= 7, the corrosion-induced tensile stress and the susceptibility to SCC have maximum values andhardly change with increasing the pH value. However, when pH <7, both the corrosion-induced tensilestress and the susceptibility to SCC reduce rapidly with decreasing the pH value. Both thecorrosion-induced tensile stress and the susceptibility to SCC have maximum values at theopen-circuit potential, decrease slightly under the anodic polarization, and reduce gradually tozero under the cathodic polarization.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(grant no.21802047)and the Scientific Research Funds of Huaqiao University(grant no.600005-Z17Y0073),Xiamen,China.
文摘Four protic ionic liquids(ILs)were synthesized via a one-step method by using benzotriazole(BTA)and benzimidazole as cations,and benzenesulfonic acid and 2-naphthalenesulfonic acid(NSA)as anions.These ILs were used as green corrosion inhibitors for brass specimens in a nitric acid solution.The structure of the protic ILs was characterized by 1H-NMR,13C-NMR,and FT-IR spectroscopy.The effects of the IL structure,IL concentration,acid concentration,and corrosion time on the surface morphology of brass specimens and the inhibition efficiency(η%)of ILs were investigated by the weight loss method combined with SEM and EDS spectroscopy.Polarization curves and impedance spectroscopy were used to analyze the electrochemical corrosion inhibition mechanism of ILs.Results showed that IL synthesis was a proton transfer process,and the proton of the–SO3H group on NSA was deprived by BTA.IL[BTA][NSA],which had a high charge density and large conjugateπband,was the most effective inhibitor for brass corrosion.Theη%of[BTA][NSA]decreased with the increase in acid concentration and corrosion time,which showed an increment with the increase in[BTA][NSA]concentration.The higher theη%of[BTA][NSA]is,the smoother the surface of the brass specimens is,and the smaller the undistributed area of Cu element will be.Corrosion inhibiting mechanism from electrochemical analysis indicated that the addition of[BTA][NSA]increased the polarization resistance of the brass electrode significantly and suppressed both anodic and cathodic reactions.
文摘After brass is coated with tin, heat treatment makes the coating metal Sn and the substrate metallic elements Cu and Zn diffuse with each other. This causes the coating composition to be changed and the interface to be strengthened. The diffusion coating with a multiphase structure formed by this process has excellent properties of antifriction and wear resistance. With the aid of scanning electron microscopy, electronic probe microanalysis and X ray diffraction, the mechanism of the properties is discussed.
文摘The Characteristic and mechanism of corrosion of brass exposed to seawater for several years, including alloys with single alpha-phase and alpha + beta phase, were investigated by means of metallograph, SEM, EDS and so on. It shows that severe corrosion with intergranular and dezincification characteristics occurred on the specimens of H-68A, which was single alpha-phase brass with As element addition. For the brass of HSn70-1A, which was single-phase alloy with ils and Sn additions, much better corrosion resistance could be exhibited due to the formation of Sn enrichment corrosion product film. Sn element is much easier to enrich at phase and grain boundaries than towards surface film. This would inhibit dezincification of the alpha + beta phase brass to some extent. However, it is not enough for the Sn element addition in the brass HSn62-1 with alpha + beta phase to resist dezincification corrosion getting through phase and grain boundaries of the brass. The alleging elements boundary diffusion plays an important role in the corrosion behavior of both alpha-phase and alpha + beta phase brass.
文摘The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
文摘1.IntroductionSuperplasticity is not merely a specialphenomenon for certain specific alley,but isone of the intrinsic properties of metallicmaterials[1].When the internal and externalconditions are suitable,superplasticity ofmetal materials will be presented.
基金Acknowledgements This work was financially supported by the National Natural Science Foundation of China ( Grant No. 50904012 ) and Natural Science Foundation of Liaoning Province (Grant No. 20092152).
文摘Dissimilar metal joining between 5A02 aluminum alloy and H62 brass sheets was conducted by gas tungsten arc welding with Zn-15% Al and Al-12% Si flux-cored filler wires. The microstructure in the weld and distribution of major alloying elements in the intelfacial layer were examined, and the tensile strength of the resultant joints was measured. Pores appeared in the weld made with Zn-15% Al flax-cored filler wire, the interracial layer mainly consisted of AlCu phase, and the specimens fractured through the weld with tensile strength of 129 MPa. When Al-12% Si flux-cored filler wire was used, Cu diffused into the weld and Al2 Cu phase formed, and the specimens fractured along the interfacial layer with tensile strength of 122 MPa.
文摘In response to environmental guidelines, a low phosphonic multipolymer was synthesized and its corrosion inhibition efficiency to brass in synthetic water was investigated through weight loss measurements and electrochemical tests. It showed that the synthesized inhibitor decreased corrosion under the conditions tested. Potentiodynamic polarization curves indicated that the new inhibitor acted as an anodic inhibitor, reducing metal dissolution. The composition of protective films formed on the brass was studied by energy-dispersive X-ray analysis (EDX). The inhibition effects were due to the formation of a protective film of the multipolymer inhibitor on the metal surface.
文摘Leaded brass alloys used progressively in many applications such as gas valves production owing to their excellent machinability, corrosion resistance and some other specifications. However, the production processes of these alloys involve some problems appearing in the last activities of production as a result of cumulative defects of previous production processes. Therefore, the current investigation studies the effect of process parameters during casting, hot extrusion and cold drawing production stages of CuZn40Pb2 leaded brass alloy on the mechanical properties. Starting with casting process, two types of charges were used. The first charge consists of 100% recycles while the second contains 30% of pure materials such as Cu, Zn and Pb in addition to the recycles. For each production stage, alloy hardness, micro-hardness, ultimate tensile strength and elongation were examined. The results illustrated that high hardness values are obtained during casting process due to some impurities such as iron and the effect of cooling rate through solidification. The hardness values decrease during extrusion process and then rise again by cold drawing for the charge of 30% pure materials. Micro-hardness values for the fractured tensile test samples appeared higher than others due to work hardening effect. The best mechanical properties as ultimate tensile strength of CuZn40Pb2 alloy products are appeared into cold forming samples with the 30% pure material added.
文摘Brass is an excellent material choice for use in most industrial and agricultural application. Brass offers much better thermal conductivity and corrosion resistance than carbon or even stainless steel. Brass is an excellent material for use in both hot and cold water industrial and residential system including those carrying portable water. This study was carried out to investigate and evaluate the influence of fossil fuel like petrol, kerosene and diesel on the corrosion performance of brass. The samples were prepared for the study by cutting brass into 1 cm2 coupons and soaking them in different small plastic containers containing petrol, kerosene and diesel. The corrosion rate of each sample for a specific period of immersion (120, 240, 360, and 480, 600 and 720 hours) was determined on average of three samples exposed under the same condition and test media in different container. The finding showed that brass is resistant to corrosion after long hours of contact in chosen liquid fossil fuels. Brass has the highest corrosion rate in petrol, followed by kerosene and least in diesel. The photomicrographs of the samples after ten days of immersion also confirmed this.
文摘Wear is a continuous process in which material is degraded with every cycle. Scientists are busy in improving the wear resistance. Approximately 75% failure in components or machine parts is due to wear. The present paper investigates experimentally the effect of orientation and normal load on alloy of copper and zinc, i.e. Brass, and calculates weight loss due to wear. To do so, a multi-orientational pin-on-disc apparatus was designed and fabricated. Experiments were carried out under normal load 05-20 N, speed 2000 rpm. Results show that the with-increasing load weight loss increases at all angular positions. The loss in weight is maximum at zero degree (horizontal position) and minimum at ninety degree (vertical position) for a particular load. Maximum wear occurs when the test specimen is held at 0° angle and minimum wear occurs when the specimen is held at 90° angle for given applied load. The circumferential distance travel is constant for all positions and for all loads but still mass loss varies.
文摘In situ observation of the growth process of bainitic plate in βbrass by means of high-temper- ature TEM is conducted.The lengthening and thickening kinetics of bainitic plate is analysed with Trivedi's model and Zener-Hillert's model,respectively.It is found that the stacking fault substructure exists just in the growth tip of fresh bainitie plate and so does the shear stress in the matrix around the tip.The measured lengthening rate of bainitic plate is not con- sistent with Trivedi's model.The thiekening process is only macroscopieally controlled by vol- ume diffusion but its nature is a shear process.