To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the p...To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness.Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg_(2)Si and the scratches on the machined surface mostly come from the iron-containing phase(α-, β-AlFeSi).Moreover, the generated Mg_(2)Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg_(2)Si with the medium size(more than 1 μm and less than 2 μm) in Al6061.展开更多
The Metal Matrix Composites application has increased in many areas of science and technology, because of its additional physical, wear and mechanical properties. In comparison with all MMC’s, aluminum-based MMC’s a...The Metal Matrix Composites application has increased in many areas of science and technology, because of its additional physical, wear and mechanical properties. In comparison with all MMC’s, aluminum-based MMC’s are finding wide applications due to their better strength to weight ratio, better stiffness, and high thermal conductivity as well as very good wear and corrosion properties. The properties of a composite mainly depend on better distribution of reinforcement in the matrix, which is very difficult to achieve. Basically Redmud is a byproduct of alumina, and it is waste product obtained during Bayer’s process. This waste product must be recycled else it may be dangerous to the environment. Redmud can be used as reinforcement for aluminium composites in order to achieve better properties. The proposed research work includes preparation of Aluminum 6061-Red mud metal matrix composites using liquid metallurgy route following stir casting technique. An alloy Al6061 containing 0.60 percent silicon and Magnesium of 0.82 percent was used as the matrix material. Two different compositions of the Aluminum 6061-Red mud composites are prepared in addition to the base matrix and evaluated for mechanical properties also the force acting on the cutting tool at different spindle speeds during machining of the composite materials were analyzed.展开更多
Al6061matrix with different amounts of nano-silver(1%and2%)was produced by stir-casting method.Producedsamples were characterized by hardness,tensile,compression and wear tests.The hardness of the specimens at room te...Al6061matrix with different amounts of nano-silver(1%and2%)was produced by stir-casting method.Producedsamples were characterized by hardness,tensile,compression and wear tests.The hardness of the specimens at room temperature wasmeasured by Brinnell hardness testing machine.The magnitude of hardness increased evidently with the function of the mass fractionof the nano-Ag particle.The polished specimens were examined with an optical microscope.The fracture surfaces of tensile andcompressive specimens were further examined by scanning electron microscopy.Wear mechanisms were discussed based on thescanning electron microscopy observations of worn surface and wear debris morphology.There is an increase in compressivestrength,ultimate tensile strength,elongation and wear resistance of the Al?Ag composites compared with base alloy.The executionof stir-casting technique is relatively homogenous and fine microstructure which improves the addition of reinforcement material inthe molten metal.The results show that Al6061?nano-silver which is the best combination of hardness can replace the conventionalmaterial for better performance and longer life.展开更多
Chicken eggshell (ES) is an aviculture byproduct that has been used as the reinforcement in the present study which is recorded worldwide as one of the vilest environmental problems. The present work deals with develo...Chicken eggshell (ES) is an aviculture byproduct that has been used as the reinforcement in the present study which is recorded worldwide as one of the vilest environmental problems. The present work deals with development of ES-reinforced Al6061 matrix composites by stir-casting process with 0 to 10 wt% of reinforcement at an interval of 2 wt%. The microstructures of the fabricated composites were examined by optical and scanning electron microscopes with energy dispersive spectrometer (SEM/EDS). Optical micrographs divulge the uniform distribution of reinforcing particles in the matrix while X-ray diffraction (XRD) patterns ensure the dispersion of ES particles reinforcement in Al6061 matrix. The properties measured include density, tensile strength and hardness values. The tensile strength and hardness of composites increase with the addition of ES particles and the maximum values were achieved at 4 wt%. Further increase of ES particles in the matrix leads to decrease in hardness and strength owing to increase in porosity.展开更多
Plasma Sprayed coatings provide protection against corrosion, erosion and wear. Inconel- 718 is a metallic coating which has good wear and erosion resistance. This is plasma sprayed on to Al6061 substrate and then sub...Plasma Sprayed coatings provide protection against corrosion, erosion and wear. Inconel- 718 is a metallic coating which has good wear and erosion resistance. This is plasma sprayed on to Al6061 substrate and then subjected to slurry erosive wear tests. It is observed that the slurry wear rates of Al6061 decreased on coating the substrate material with Inconel- 718.展开更多
In this investigation, an attempt has been made to develop Al6061-Frit particulate metal matrix composites through stir casting technique using metal molds and to study the corrosion behaviour. Pre heated frit particl...In this investigation, an attempt has been made to develop Al6061-Frit particulate metal matrix composites through stir casting technique using metal molds and to study the corrosion behaviour. Pre heated frit particles were added to matrix as reinforcement. Al6061 containing 2 wt% to 8 wt % in steps of 2 wt % of frit particulate composites were prepared. Corrosion tests were conducted by using Potentiostat model SEP238C where 3.5% NaCl solution was used as corrodent. The corrosion rate of metal matrix composites was lower than that of matrix material Al6061 under the corrosive atmosphere for both un-heat treated and heat treated conditions.展开更多
Beryl-Al6061 alloy composites having 2-12 wt% of beryl particles were fabricated by liquid metallurgy (stir cast) method. The tensile and wear properties of beryl-Al6061 composites have been evaluated and compared wit...Beryl-Al6061 alloy composites having 2-12 wt% of beryl particles were fabricated by liquid metallurgy (stir cast) method. The tensile and wear properties of beryl-Al6061 composites have been evaluated and compared with its base alloy. The results revealed that the Al6061-10 wt% of beryl composites shows an improvement of 15.38% in tensile strength and specific wear rate decreases by 8.9% at normal load of 9.81N when compared to matrix i.e. base alloy. Significant improvement in tensile properties and hardness are noticed as the wt% of the beryl particles increases. The microstructures of the composites were studied to know the uniform dispersion of the beryl particles in matrix. It has been observed that addition of beryl particles significantly improves ultimate tensile strength and hardness properties as compared with that of unreinforced matrix.展开更多
The present paper involves firstly in the studies of corrosion properties of Al 6061 metal matrix composites reinforced with varying percentage of uncoated and Cu coated silicon carbide in 3.5 wt% NaCl solution using ...The present paper involves firstly in the studies of corrosion properties of Al 6061 metal matrix composites reinforced with varying percentage of uncoated and Cu coated silicon carbide in 3.5 wt% NaCl solution using weight loss method. The processing route used for the composites was stir casting technique. Mass loss and corrosion rate measurements were utilized as criteria for evaluating the corrosion behavior of composites. The surface morphology of composites after the corrosion test is determined by using scanning electron microscopy. It has been observed that copper as reinforcement coating reduces the corrosion resistance of composites in comparison to uncoated reinforcements and monolithic alloy.展开更多
The metal matrix composite (MMC), despite of its high stiffness, strength, corrosion resistance, wear resistance, non-react with chemicals and so many other tailored qualities which are never obtained in alloy of meta...The metal matrix composite (MMC), despite of its high stiffness, strength, corrosion resistance, wear resistance, non-react with chemicals and so many other tailored qualities which are never obtained in alloy of metals, has limited utilization due to the high cost of fabrication. In this study, a modest attempt has been made to find out the process parameters at which best mechanical properties of Al6061, 4% Cu and reinforced 5% SiCP ceramic MMC can be obtained. The addition of 4% Cu in Al6061 is more or less comparable to the composition duralumin, which are widely used in aerospace applications. SiCP is hard and has linear thermal expansion at high temperature. With reinforcement of SiCP in Al6061-Cu alloy, it can be postulated that hardness of MMC retains at high temperature applications. An analysis of Variance (ANOVA) and linear regression was used for analysis of data with the help of SPSS (Version-17.0). Independent parameters are five levels of pouring rates (1.5 cm/s, 2.0 cm/s, 2.5 cm/s, 3.0 cm/s and 3.5 cm/s), and material type (Al6061 + 4% Cu alloy and Al6061 + 4% Cu, reinforced 5% SiCp MMC processed using stir casting technique) and dependent parameters are hardness and impact strength material removal rates of workpiece. It is found that at different pouring rates material hardness and impact strength of workpiece are highly significant but the material removal rate of workpiece is having no significance value. At pouring rate of 2.5 cm/s and 700℃ ± 5℃ pouring temperature, optimum values of hardness and impact strength are observed as compared to other values of pouring rates (1.5 cm/s, 2.0 cm/s, 3.0 cm/s and 3.5 cm/s). Material Removal rate for work pieces of Al6061 + 4% Cu alloy is less as compared to MMC. So it can be concluded that MMC has better machining ability compared to Al6061 + 4% Cu alloy. Material removal rate of Al6061 + 4% Cu, reinforced 5% SiCP MMC has maximum values at 1.5 cm/s pouring rate compared to 2.0 cm/s, 2.5 cm/s, 3.0 cm/s and 3.5 cm/s pouring rates. With reinforcement 展开更多
A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied.The corrosion resistance of REM conversion coating was examined by electrochemical impedance s...A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied.The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy (EIS).REM conversion coating produced very corrosion resistant surface of Al 6061/SiCp MMC.The X ray diffraction (XRD) analysis revealed that REM conversion coatings exhibited non crystalline structure.The composition of REM conversion coating was studied by X ray photoelectron spectroscopy (XPS).The coatings consisted of cerium oxide and hydrated cerium oxide.Some of Ce3+were oxidized to Ce4+during the formation of the first layer coating in the solution containing Ce3+.During the course of exposing the specimens in open air,some of the residual Ce3+were oxidized to Ce4+.REM conversion coating formed in the solution containing Ce4+consisted entirely of Ce4+compounds.展开更多
基金Funded by Natural Science Foundation of Guangdong Province,China (No.2017A030313330)Science and Technology Program of Guangzhou (No.201804020040)。
文摘To improve the surface quality for aluminum alloy 6061(Al6061) in ultra-precision machining, we investigated the factors affecting the surface finish in single point diamond turning(SPDT)by studying influence of the precipitates generation of Al6061 on surface integrity and surface roughness.Based on the Johnson-Mehl-Avrami solid phase transformation kinetics equation, theoretical and experimental studies were conducted to build the relationship between the aging condition and the type, size and number of the precipitates for Al6061. Diamond cutting experiments were conducted to machine Al6061 samples under different aging conditions. The experimental results show that, the protruding on the chip surface is mainly Mg_(2)Si and the scratches on the machined surface mostly come from the iron-containing phase(α-, β-AlFeSi).Moreover, the generated Mg_(2)Si and α-, β-AlFeSi affect the surface integrity and the diamond turned surface roughness. Especially, the achieved surface roughness in SPDT is consistent with the variation of the number of AlFeSi and Mg_(2)Si with the medium size(more than 1 μm and less than 2 μm) in Al6061.
文摘The Metal Matrix Composites application has increased in many areas of science and technology, because of its additional physical, wear and mechanical properties. In comparison with all MMC’s, aluminum-based MMC’s are finding wide applications due to their better strength to weight ratio, better stiffness, and high thermal conductivity as well as very good wear and corrosion properties. The properties of a composite mainly depend on better distribution of reinforcement in the matrix, which is very difficult to achieve. Basically Redmud is a byproduct of alumina, and it is waste product obtained during Bayer’s process. This waste product must be recycled else it may be dangerous to the environment. Redmud can be used as reinforcement for aluminium composites in order to achieve better properties. The proposed research work includes preparation of Aluminum 6061-Red mud metal matrix composites using liquid metallurgy route following stir casting technique. An alloy Al6061 containing 0.60 percent silicon and Magnesium of 0.82 percent was used as the matrix material. Two different compositions of the Aluminum 6061-Red mud composites are prepared in addition to the base matrix and evaluated for mechanical properties also the force acting on the cutting tool at different spindle speeds during machining of the composite materials were analyzed.
文摘Al6061matrix with different amounts of nano-silver(1%and2%)was produced by stir-casting method.Producedsamples were characterized by hardness,tensile,compression and wear tests.The hardness of the specimens at room temperature wasmeasured by Brinnell hardness testing machine.The magnitude of hardness increased evidently with the function of the mass fractionof the nano-Ag particle.The polished specimens were examined with an optical microscope.The fracture surfaces of tensile andcompressive specimens were further examined by scanning electron microscopy.Wear mechanisms were discussed based on thescanning electron microscopy observations of worn surface and wear debris morphology.There is an increase in compressivestrength,ultimate tensile strength,elongation and wear resistance of the Al?Ag composites compared with base alloy.The executionof stir-casting technique is relatively homogenous and fine microstructure which improves the addition of reinforcement material inthe molten metal.The results show that Al6061?nano-silver which is the best combination of hardness can replace the conventionalmaterial for better performance and longer life.
文摘Chicken eggshell (ES) is an aviculture byproduct that has been used as the reinforcement in the present study which is recorded worldwide as one of the vilest environmental problems. The present work deals with development of ES-reinforced Al6061 matrix composites by stir-casting process with 0 to 10 wt% of reinforcement at an interval of 2 wt%. The microstructures of the fabricated composites were examined by optical and scanning electron microscopes with energy dispersive spectrometer (SEM/EDS). Optical micrographs divulge the uniform distribution of reinforcing particles in the matrix while X-ray diffraction (XRD) patterns ensure the dispersion of ES particles reinforcement in Al6061 matrix. The properties measured include density, tensile strength and hardness values. The tensile strength and hardness of composites increase with the addition of ES particles and the maximum values were achieved at 4 wt%. Further increase of ES particles in the matrix leads to decrease in hardness and strength owing to increase in porosity.
文摘Plasma Sprayed coatings provide protection against corrosion, erosion and wear. Inconel- 718 is a metallic coating which has good wear and erosion resistance. This is plasma sprayed on to Al6061 substrate and then subjected to slurry erosive wear tests. It is observed that the slurry wear rates of Al6061 decreased on coating the substrate material with Inconel- 718.
文摘In this investigation, an attempt has been made to develop Al6061-Frit particulate metal matrix composites through stir casting technique using metal molds and to study the corrosion behaviour. Pre heated frit particles were added to matrix as reinforcement. Al6061 containing 2 wt% to 8 wt % in steps of 2 wt % of frit particulate composites were prepared. Corrosion tests were conducted by using Potentiostat model SEP238C where 3.5% NaCl solution was used as corrodent. The corrosion rate of metal matrix composites was lower than that of matrix material Al6061 under the corrosive atmosphere for both un-heat treated and heat treated conditions.
文摘Beryl-Al6061 alloy composites having 2-12 wt% of beryl particles were fabricated by liquid metallurgy (stir cast) method. The tensile and wear properties of beryl-Al6061 composites have been evaluated and compared with its base alloy. The results revealed that the Al6061-10 wt% of beryl composites shows an improvement of 15.38% in tensile strength and specific wear rate decreases by 8.9% at normal load of 9.81N when compared to matrix i.e. base alloy. Significant improvement in tensile properties and hardness are noticed as the wt% of the beryl particles increases. The microstructures of the composites were studied to know the uniform dispersion of the beryl particles in matrix. It has been observed that addition of beryl particles significantly improves ultimate tensile strength and hardness properties as compared with that of unreinforced matrix.
文摘The present paper involves firstly in the studies of corrosion properties of Al 6061 metal matrix composites reinforced with varying percentage of uncoated and Cu coated silicon carbide in 3.5 wt% NaCl solution using weight loss method. The processing route used for the composites was stir casting technique. Mass loss and corrosion rate measurements were utilized as criteria for evaluating the corrosion behavior of composites. The surface morphology of composites after the corrosion test is determined by using scanning electron microscopy. It has been observed that copper as reinforcement coating reduces the corrosion resistance of composites in comparison to uncoated reinforcements and monolithic alloy.
文摘The metal matrix composite (MMC), despite of its high stiffness, strength, corrosion resistance, wear resistance, non-react with chemicals and so many other tailored qualities which are never obtained in alloy of metals, has limited utilization due to the high cost of fabrication. In this study, a modest attempt has been made to find out the process parameters at which best mechanical properties of Al6061, 4% Cu and reinforced 5% SiCP ceramic MMC can be obtained. The addition of 4% Cu in Al6061 is more or less comparable to the composition duralumin, which are widely used in aerospace applications. SiCP is hard and has linear thermal expansion at high temperature. With reinforcement of SiCP in Al6061-Cu alloy, it can be postulated that hardness of MMC retains at high temperature applications. An analysis of Variance (ANOVA) and linear regression was used for analysis of data with the help of SPSS (Version-17.0). Independent parameters are five levels of pouring rates (1.5 cm/s, 2.0 cm/s, 2.5 cm/s, 3.0 cm/s and 3.5 cm/s), and material type (Al6061 + 4% Cu alloy and Al6061 + 4% Cu, reinforced 5% SiCp MMC processed using stir casting technique) and dependent parameters are hardness and impact strength material removal rates of workpiece. It is found that at different pouring rates material hardness and impact strength of workpiece are highly significant but the material removal rate of workpiece is having no significance value. At pouring rate of 2.5 cm/s and 700℃ ± 5℃ pouring temperature, optimum values of hardness and impact strength are observed as compared to other values of pouring rates (1.5 cm/s, 2.0 cm/s, 3.0 cm/s and 3.5 cm/s). Material Removal rate for work pieces of Al6061 + 4% Cu alloy is less as compared to MMC. So it can be concluded that MMC has better machining ability compared to Al6061 + 4% Cu alloy. Material removal rate of Al6061 + 4% Cu, reinforced 5% SiCP MMC has maximum values at 1.5 cm/s pouring rate compared to 2.0 cm/s, 2.5 cm/s, 3.0 cm/s and 3.5 cm/s pouring rates. With reinforcement
文摘A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied.The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy (EIS).REM conversion coating produced very corrosion resistant surface of Al 6061/SiCp MMC.The X ray diffraction (XRD) analysis revealed that REM conversion coatings exhibited non crystalline structure.The composition of REM conversion coating was studied by X ray photoelectron spectroscopy (XPS).The coatings consisted of cerium oxide and hydrated cerium oxide.Some of Ce3+were oxidized to Ce4+during the formation of the first layer coating in the solution containing Ce3+.During the course of exposing the specimens in open air,some of the residual Ce3+were oxidized to Ce4+.REM conversion coating formed in the solution containing Ce4+consisted entirely of Ce4+compounds.
