Nanofluid minimum quantity lubrication(NMQL)is a green processing technology.Cottonseed oil is suitable as base oil because of excellent lubrication performance,low freezing temperature,and high yield.Al_(2)O_(3)nanop...Nanofluid minimum quantity lubrication(NMQL)is a green processing technology.Cottonseed oil is suitable as base oil because of excellent lubrication performance,low freezing temperature,and high yield.Al_(2)O_(3)nanoparticles improve not only the heat transfer capacity but also the lubrication performance.The physical and chemical proper-ties of nanofluid change when Al_(2)O_(3)nanoparticles are added.However,the effects of the concentration of nanofluid on lubrication performance remain unknown.Furthermore,the mechanisms of interaction between Al_(2)O_(3)nanoparti-cles and cottonseed oil are unclear.In this research,nanofluid is prepared by adding different mass concentrations of Al_(2)O_(3)nanoparticles(0,0.2%,0.5%,1%,1.5%,and 2%wt)to cottonseed oil during minimum quantity lubrication(MQL)milling 45 steel.The tribological properties of nanofluid with different concentrations at the tool/workpiece interface are studied through macro-evaluation parameters(milling force,specific energy)and micro-evaluation parameters(surface roughness,micro morphology,contact angle).The result show that the specific energy is at the minimum(114 J/mm^(3)),and the roughness value is the lowest(1.63μm)when the concentration is 0.5 wt%.The surfaces of the chip and workpiece are the smoothest,and the contact angle is the lowest,indicating that the tribological proper-ties are the best under 0.5 wt%.This research investigates the intercoupling mechanisms of Al_(2)O_(3)nanoparticles and cottonseed base oil,and acquires the optimal Al_(2)O_(3)nanofluid concentration to receive satisfactory tribological properties.展开更多
The contact fatigue life of machine elements is affected by pitting, wear and so on, under heavier loading conditions. Increasing the fatigue life requires mainly the improvements of lubricating condition, operating c...The contact fatigue life of machine elements is affected by pitting, wear and so on, under heavier loading conditions. Increasing the fatigue life requires mainly the improvements of lubricating condition, operating condition and materials. In order to improve the lubricating condition, it is necessary to investigate the relation of the microscopic surface texturing and the contact modes of machine elements. In this paper, thus, the pressure and oil film thickness of the contact between sphere and the plate with 5 kinds surface texturing were calculated using a commercial software based on Reynolds equation. There was sufficient evidence to suggest that the dimple shape was the optimum texturing to increase the lubricating condition.展开更多
In the present study,the effect of reduction of cutting fluid consumption on the surface quality and tool wear was studied.Mathematical models were developed to predict the surface roughness using response surface met...In the present study,the effect of reduction of cutting fluid consumption on the surface quality and tool wear was studied.Mathematical models were developed to predict the surface roughness using response surface methodology(RSM).Analysis of variance(ANOVA)was used to investigate the significance of the developed regression models.The results showed that the coefficient of determination values(R^2)for the developed models was 97.46%for dry,89.32%for flood mode(FM),and 99.44%for MQL,showing the high accuracy of fitted models.Also,under the minimum quantity lubrication(MQL)condition,the surface roughness improved by 23%−44%and 19%−41%compared with dry and FM,respectively,and the SEM images of machined surface proved the statement.The prepared SEM images of tool rake face also showed a considerable decrease in adhesion wear.Built-up edge and built-up layer were the two main products of the adhesion wear,and energy-dispersive X-ray spectroscopy(EDX)analysis of specific points on the tool faces helped to discover the chemical compositions of adhered materials.By changing dry and FM to MQL mode,dominant mechanism of tool wear in machining aluminum alloy was significantly decreased.Breakage wear that led to early failure of cutting edge was also controlled by MQL technique.展开更多
In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inhere...In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.展开更多
A series of bis-quaternary ammonium compounds（bis-QACs） N,N＇-hevamethylenebis（1-alkyl-4-carbamoyl pyridinium bromide）（4BCAP-6,n）（alkyl chain length,n=8,10,12,14,16 and 18） were synthesized and characterized.T...A series of bis-quaternary ammonium compounds（bis-QACs） N,N＇-hevamethylenebis（1-alkyl-4-carbamoyl pyridinium bromide）（4BCAP-6,n）（alkyl chain length,n=8,10,12,14,16 and 18） were synthesized and characterized.Their surface tensions,critical micelle concentrations（CMC）,and antimicrobial activities were evaluated.4BCAP-6,10 exhibited the strongest antimicrobial activities except for that against Proteus vulgari.The activities of 4BCAP-6.n against Escherichia coli zk126 were not significantly influenced by temperature.pH and initial bacteria concentration.These results indicate that bis-QACs exhibit high antimicrobial activity regardless of the environmental conditions.展开更多
From the realism of science, and taking the guide of EINSTEIN’s Relativity as guide, this article called in question the present theory of the sustainable development by the rational thinking of philosophy and a clos...From the realism of science, and taking the guide of EINSTEIN’s Relativity as guide, this article called in question the present theory of the sustainable development by the rational thinking of philosophy and a close logic inference. It is found that there are many paradoxes to the theory. Through more deepening and meticulous inference, we arrived at philosophic language of science about the sustainable development. The sustainable development is "non-sustainable development", and the non-sustainable development is "the best sustainable development". While carrying out philosophical principle thinking and repeating science demonstration for the sustainable development, this article got further confirmation that the existence of human being at the minimum environment cost may help them obtain motive power of the sustainable development. In fact, this foundation motive power exists in the flow of development in different organization levels, meanwhile it exists in strategy of intuition living of the ancient people. Only in relative lower environment cost to live can we get the support system of science for the sustainable development, and be able really to achieve the basic goal of the sustainable development.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51806112,51975305)PhD Research Startup Foundation of Qingdao University of Technology,China(Grant Nos.JC2022-012,20312008).
文摘Nanofluid minimum quantity lubrication(NMQL)is a green processing technology.Cottonseed oil is suitable as base oil because of excellent lubrication performance,low freezing temperature,and high yield.Al_(2)O_(3)nanoparticles improve not only the heat transfer capacity but also the lubrication performance.The physical and chemical proper-ties of nanofluid change when Al_(2)O_(3)nanoparticles are added.However,the effects of the concentration of nanofluid on lubrication performance remain unknown.Furthermore,the mechanisms of interaction between Al_(2)O_(3)nanoparti-cles and cottonseed oil are unclear.In this research,nanofluid is prepared by adding different mass concentrations of Al_(2)O_(3)nanoparticles(0,0.2%,0.5%,1%,1.5%,and 2%wt)to cottonseed oil during minimum quantity lubrication(MQL)milling 45 steel.The tribological properties of nanofluid with different concentrations at the tool/workpiece interface are studied through macro-evaluation parameters(milling force,specific energy)and micro-evaluation parameters(surface roughness,micro morphology,contact angle).The result show that the specific energy is at the minimum(114 J/mm^(3)),and the roughness value is the lowest(1.63μm)when the concentration is 0.5 wt%.The surfaces of the chip and workpiece are the smoothest,and the contact angle is the lowest,indicating that the tribological proper-ties are the best under 0.5 wt%.This research investigates the intercoupling mechanisms of Al_(2)O_(3)nanoparticles and cottonseed base oil,and acquires the optimal Al_(2)O_(3)nanofluid concentration to receive satisfactory tribological properties.
文摘The contact fatigue life of machine elements is affected by pitting, wear and so on, under heavier loading conditions. Increasing the fatigue life requires mainly the improvements of lubricating condition, operating condition and materials. In order to improve the lubricating condition, it is necessary to investigate the relation of the microscopic surface texturing and the contact modes of machine elements. In this paper, thus, the pressure and oil film thickness of the contact between sphere and the plate with 5 kinds surface texturing were calculated using a commercial software based on Reynolds equation. There was sufficient evidence to suggest that the dimple shape was the optimum texturing to increase the lubricating condition.
文摘In the present study,the effect of reduction of cutting fluid consumption on the surface quality and tool wear was studied.Mathematical models were developed to predict the surface roughness using response surface methodology(RSM).Analysis of variance(ANOVA)was used to investigate the significance of the developed regression models.The results showed that the coefficient of determination values(R^2)for the developed models was 97.46%for dry,89.32%for flood mode(FM),and 99.44%for MQL,showing the high accuracy of fitted models.Also,under the minimum quantity lubrication(MQL)condition,the surface roughness improved by 23%−44%and 19%−41%compared with dry and FM,respectively,and the SEM images of machined surface proved the statement.The prepared SEM images of tool rake face also showed a considerable decrease in adhesion wear.Built-up edge and built-up layer were the two main products of the adhesion wear,and energy-dispersive X-ray spectroscopy(EDX)analysis of specific points on the tool faces helped to discover the chemical compositions of adhered materials.By changing dry and FM to MQL mode,dominant mechanism of tool wear in machining aluminum alloy was significantly decreased.Breakage wear that led to early failure of cutting edge was also controlled by MQL technique.
基金Project (No. DEARS/CASR/R-01/2001/D-934 (30)) supported by Directorate of Advisory Extension and Research Services (DAERS), Committee for Advanced Studies & Research (CASR), BUET, Dhaka, Bangladesh
文摘In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.
基金supported by the National Natural Science Foundation of China(No.20972120)Doctor Fund of Henan University of Technology(No.150392)
文摘A series of bis-quaternary ammonium compounds（bis-QACs） N,N＇-hevamethylenebis（1-alkyl-4-carbamoyl pyridinium bromide）（4BCAP-6,n）（alkyl chain length,n=8,10,12,14,16 and 18） were synthesized and characterized.Their surface tensions,critical micelle concentrations（CMC）,and antimicrobial activities were evaluated.4BCAP-6,10 exhibited the strongest antimicrobial activities except for that against Proteus vulgari.The activities of 4BCAP-6.n against Escherichia coli zk126 were not significantly influenced by temperature.pH and initial bacteria concentration.These results indicate that bis-QACs exhibit high antimicrobial activity regardless of the environmental conditions.
基金Under the auspices of National Excellent Youth Foundation of China(No.40125003)
文摘From the realism of science, and taking the guide of EINSTEIN’s Relativity as guide, this article called in question the present theory of the sustainable development by the rational thinking of philosophy and a close logic inference. It is found that there are many paradoxes to the theory. Through more deepening and meticulous inference, we arrived at philosophic language of science about the sustainable development. The sustainable development is "non-sustainable development", and the non-sustainable development is "the best sustainable development". While carrying out philosophical principle thinking and repeating science demonstration for the sustainable development, this article got further confirmation that the existence of human being at the minimum environment cost may help them obtain motive power of the sustainable development. In fact, this foundation motive power exists in the flow of development in different organization levels, meanwhile it exists in strategy of intuition living of the ancient people. Only in relative lower environment cost to live can we get the support system of science for the sustainable development, and be able really to achieve the basic goal of the sustainable development.
