| Aluminum and its alloys have advantages such as light weight,high strength,and good electrical and thermal conductivity,and are widely used in the manufacturing of components in transportation,aerospace,shipbuilding,military and other fields.They are also the preferred materials for lightweight engine pistons.However,the wear resistance and corrosion resistance of aluminum and its alloys are poor,and they are prone to wear and thermal corrosion during the high-speed reciprocating motion of engine pistons.Therefore,surface treatment of aluminum components is required to improve their wear resistance and corrosion resistance.In this paper,the in-situ growth method was mainly used to prepare a water-based layer of layered double hydroxides(LDHs)on the surface of aluminum alloy anodized films,and the film layer was modified to improve the comprehensive performance of aluminum components such as wear resistance and corrosion resistance.A porous anodic oxide film was prepared on the surface of aluminum alloy using anodic oxidation technology,and a magnesium-aluminum layered double hydroxide(MgAl-LDH)film was synthesized on the anodic oxide film surface via an in-situ growth method.A single variable experiment was designed to find the optimal combination of process parameters,and the effects of reaction time,reaction temperature,and acidity/alkalinity of the reaction solution on the properties of the MgAl-LDH film were investigated.The basic physicochemical properties of the MgAl-LDH film were characterized and analyzed using SEM,XRD,FTIR,Vickers hardness tester,and other methods.The friction and corrosion resistance properties of the water slide stone film were tested using an SFT-2M type ball disk friction and wear tester and an electrochemical workstation.The results showed that the MgAl-LDH film properties varied with different reaction parameters,but all exhibited functions of reducing friction and corrosion prevention.The MgAl-LDH film can improve the friction properties of the oxidized aluminum matrix while protecting it from corrosive substances in the environment.By utilizing the ion-exchange characteristics of the interlayer space in hydrotalcite,MgAlLDH membrane layers were prepared using the optimal process parameter combination,and intercalation modifications were carried out using sodium metavanadate and tetradecyl sulfate to prepare LDH-SV and LDH-TU membrane layers,respectively.The effects of reaction solution concentration,reaction time,and reaction temperature on the surface morphology,crystal structure,and corrosion resistance of the modified membrane layers were investigated.The results showed that compared to the MgAl-LDH membrane layer,the self-corrosion current density of LDH-SV and LDH-TU membrane layers decreased by one order of magnitude,and the corrosion resistance was improved.Meanwhile,it was found that sodium metavanadate can regulate the interlayer spacing of the hydrotalcite membrane layer.The interlayer distance of the LDH-SV membrane layer can reach 0.47 nm,which is 17.5%larger than that of the MgAlLDH membrane layer.Finally,dry sliding tests were conducted on MgAl-LDH and LDH-SV composite membranes to analyze the effect of different reaction conditions on the friction coefficient,wear amount,and wear morphology of the composite membrane,and to compare the test results with those of the alumina film substrate material.A tribological model characterizing the antifriction and wear-resistant mechanism of LDH-SV membrane layer was established.The study found that the synergistic effect of the brucite lubricating layer,deformed brucite nanosheets,and alumina film significantly improved the anti-friction and wear-resistant performance of the aluminum-based material.Due to the increased layer spacing of LDH-SV membrane,the electrostatic attraction between the upper and lower brucite layers weakened,thereby reducing the resistance to relative sliding during the friction process.Therefore,the tribological performance was further improved,and the friction coefficient could be reduced from about 0.35 to 0.1.The scratch test results of the MgAl-LDH film layer also show that the hydrotalcite film layer has good interfacial bonding strength at the film base and is able to maintain good film base bonding under critical loading. |
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