Preparation And Performance Of Functional Al-base Films On Magnet

Sintering NdFeB magnets,served as a very new promising functional material,is widely used in acoustics,electronics,electronics,communications,aerospace,automation and biology for its high magnetic saturation flux,coercivity,magnetic energy,well machine processing characteristics and comparative low price.But sintering NdFeB magnet is easily prone to corrosion in the electrochemical environment?warm and humid,high temperature,etc.?,resulting in the decrease of its magnetism and the anti-corrosion work application of the sintered NdFeB.Especially in recent years,the acceleration of motor development requires the NdFeB permanent magnet to work in a more complex environment,and higher requirements for the protection of magnets.With the development of nanometer semiconductor materials,photocathode protection is widely used in the field of metal anti-corrosion.In certain light conditions,nanometer semiconductor materials can produce light electronic-hole pair,enough electron mobility makes the metal to metal surface potential drop to the protection area,reduce the generation of corrosion.Due to the special energy band structure of titanium dioxide and zinc oxide,it has a good photocathode protection effect on metal protection.To promote the corrosion resistance of sintering NdFeB magnet better,this paper mainly on the basis of previous research,through the optimization of process preparation of nano Al thin film structure,introducing nanometer semiconductor material?TiO₂ and ZnO?to product Al base functional films?Al/TiO₂,Al/ZnO and Al/TiO₂/ZnO?and improved the corrosion resistance of sintering NdFeB magnet working in the special industrial environment.The main conclusions are as follows:1.The optimum process of pulsed electrodeposition of Al films on NdFeB surface at room temperature ionic liquid?AlCl₃-EMIC?was obtained.The results showed that the Al films obtained on the NdFeB surface is smooth,when the deposited current density is 12.5mA/cm²,the pulse frequency is 5Hz and the duty cycle is 0.5.The self-corrosion potential is 0.8V in the 3.5%NaCl solution,was lower than the constant voltage and the negative shift was 0.2V,and the self-corrosion current density is the smallest in the whole experimental system.2.The Al/TiO₂ composite film was obtained on the surface of NdFeB by sol-gel spin coating method on the base of the optimum NdFeB surface Al film.The effect of heat treatment temperature and binder content on the composite membrane was also studied.When the heat treatment temperature of 450?,the binder content of 10mg/L,the self-corrosion potential was negative shift 50mV?VS.NdFeB/Al?,and the photocurrent density was 112?A/cm² of NdFeB/Al/TiO₂ film,in the 3.5%NaCl solution as expose d to ultraviolet xenon lamp?365nm?.3.The Al/ZnO composite film was obtained on the surface of NdFeB by sol-gel spin coating method on the base of the optimum NdFeB surface Al film.The effect of binder content on the composite membrane was also studied.When the heat treatment temperature of 500?,the binder content of 10mg/L,the self-corrosion potential was negative shift 44mV?VS.NdFeB/Al?,and the photocurrent density was 104?A/cm² of NdFeB/Al/ZnO film,in the 3.5%NaCl solution as expose d to xenon lamp?>420nm?.4.The Al/TiO₂/ZnO composite film was obtained on the surface of NdFeB by sol-gel spin coating method on the base of the optimum NdFeB surface Al film.The method of step by step heat treatment is used to avoid the mutual inhibition in the process of film formation.The experimental results show that the self-corrosion potential was negative shift 101mV?VS.NdFeB/Al?,and the photocurrent density was 141?A/cm² of NdFeB/Al/ZnO film,in the 3.5%NaCl solution as exposed to xenon lamp?full band?.