通过对比试验发现:混合稀土含量对ZL201组织和性能都有很大的影响,当稀土含量在0.6%左右时,合金显微组织变得非常细小,硬度也达到很高的数值;但超过这个含量后,合金晶粒开始变粗,硬度也随之降低。最后,利用动力学的相关原理,证明了稀土元素发挥变质作用时最佳含量的存在。

The effects of different magnesium contents(WMg=1.1%,1.3%,1.5%,1.7%)on the microstructure,mechanical properties and corrosion resistance of ZL201 Al-Cu alloy have been investigated by microscope,MH-3micro hardness tester,HV1-10A low-Vickers hardness tester and CHI660B electrochemical station.The experimental results show that the grain size of ZL201 alloy was refined with the increasing addition of magnesium.With the content of magnesium 1.7%,small and more uniform distribution of the better microstructures can be gained,the corrosion resistant property is the best.

Effects of copper sulfate concentration,complexing agent concentration ratio,formaldehyde concentration,rare earth content and temperature on copper deposition rate,coating microstructure of electroless copper plating on ceramic were discussed.Results showed that with the increase in copper sulfate concentration and temperature and decrease in complexing agent ratio,the Cu deposition rate was increased but bath stability decreased;with increasing formaldehyde concentration and rare earth content,the Cu deposition rate was increased at first and then decreased.By adding rare earth Ce salt,copper particles got refined and copper depositon became even,especially when cerium sulfate content was 0.8g/L,copper coating became more level,finer and less pores.

The optimum electric voltage,time,temperature of sulfuric acid-boric acid anodic oxidation electrolyte for aluminum alloy were obtained by orthogonal experiment,and then different amounts of cerous sulfate were added in the optimum electrolyte.The corrosion resistance of aluminum alloy anodizing film obtained from these electrolytes was determined by salt spray and immersion tests and polarization curve measurement.The content of cerous sulfate was optimized.

It was found through the contrast experiment that the content of mixed RE had a great influence on the properties and microstructure of ZL201.When the contents of mixed RE reach 0.6%,the microstructure of the alloy changed extremely tiny and the hardness also achieves a very high value.But surpassed this contents,the crystal grain of alloy became coarsen,and the hardness reduced along with.The aging treatment had a certain degree influence on the properties and microstructure of the metal mould casting,but the influence was insignificancy.

The corrosion resistance,wearing resistance,hardness of aluminum alloy substrate were greatly improved by aluminum alloy anodic oxidation technology.Anodic oxidized films with different properties were obtained in different acid solution processes.In this review,the crafts of anodic oxidation in conventional acidic electrolyte were summarized,especially the process and development of sulfuric acid-boric acid anodic oxidation.The trend of anodic oxidation technology was briefly pointed out.

Amorphous and nanocrystalline Fe-based soft magnetic alloys which have excellent soft magnetic properties,simple manufacturing process and low cost,have been widely used in electrical and electronic communications industries now.This article summarizes the classification and preparation methods of Fe-based soft magnetism alloys,lays emphasis on describing the current research and prospect of them.

The effect of solid solution treatment time on six kinds of Mg alloyed ZL201 was analyzed by mechanical property test and optical microscope.The results show that the ZL201 alloy with 1.5% to 1.7% of Mg could gain small and more uniform distributed fine microstructures.After 535 ℃ × 8h and 535 ℃ × 12 h solution treatment,the hardness of the six kinds of components was slightly lower,and the alloys got strengthened by solid solution treatment at 535 ℃ × 4 h.The alloy containing 1.7%Mg got the best effect of solution treatment.The result provides the reference for parameter selection and further optimization of heat-treatment process of this alloy.

CNT-Ag-G composite brushes were fabricated by means of powder metallurgy. Under 10A/cm~2 and different pressure(5N/cm~2～30N/cm~2)conditions,the contact voltage drop of CNT-Ag-G composite brushes was studied and worn surface was observed using SEM. The results show:when pressure is small (10N/cm~2,5N/cm~2),because of the increase in the roughness and intensification of the abrasive properties of the metal counterbody surface,the contact voltage drop of CNT-Ag-G composite is bigger;with the increase of pressure, the contact area between brush and commutator increases and the contact resistance decreases and leads to the decrease of contact voltage drop. Due to the polishing of CNT, the lubricating film doesn't thicken and contact voltage drop of composite remains constant with the increase of wear time.

The effect of pressure various on the mechanical and electrical wear properties of CNTs-Ag-G composites at 10A/cm~2 were studied.The results show that the wear volume loss of composites increases with the increase of pressure under mechanical wear,but the wear volume loss of composites varies with the change of pressure by U shape under electrical wear.When the pressure become smaller,the electrical wear volume loss of composites become larger because of the additional electrical and spark wear.When the pressure is bigger,the electrical wear volume loss also become larger due to the discontinuous lubricating film,adhesion and ploughing.The wear volume loss of positive brush is more than that of negative brush.The friction coefficient of composites increases with the increase of pressure,and the friction coefficient of composites under electrical wear is greater than that under mechanical wear.Addition of CNTs-Ag-G can improve the electrical friction and wear properties of composites.

研究了碳纳米管的表面镀覆处理对复合材料性能的影响,结果表明,碳纳米管经过化学镀银处理后用于制造复合材料,可以改善碳纳米管在金属基体中的分散性,提高复合材料的界面结合力,提高复合材料的硬度、导电性、抗弯强度.断口分析表明,碳纳米管未进行化学镀时,由于碳纳米管-银的弱界面结合,使碳纳米管拔出长度较长,在碳纳米管经化学镀后,由于改善了碳纳米管-银的界面结合状态,使碳纳米管拔出长度较短.

Carbon nanotubes-silver composites were prepared by powder metallurgical method. Influence of the content of carbon nanotubes on the mechanical properties of the composites was investigated. The results show that the hardness and density of the composites increase with the increase of carbon nanotubes when the content of carbon nanotubes is less than 11%, the hardness and density of the composites decrease with the increase of carbon nanotubes when the content of carbon nanotubes is higher than 11%. Bending strength of the composite materials is not obviously reinforced by carbon nanotubes, because of poor interfacial bonding between the multiwall carbon nanotubes and silver matrix and lower stress transfer in tension than in compression.

In this paper, CNT–Ag–G composite brushes were fabricated by means of powder metallurgy method. The friction coefficient, wear volume loss and contact voltage drop of composites with and without current were investigated and worn surface were observed using SEM. The results showed that the wear volume loss of composites with current was greater than that without current. The primary cause of the unfavourable influence of an electric current on brush was the increase in the roughness and intensification of the abrasive properties of the metal counterbody surface. Because of oxidation reaction and weakening of the bond between the grains in the materials of the brush surface layer, the wear volume loss of positive brush was larger than that of negative brush. Due to the forming of continuous lubrication film between brush and ring under mechanical wear, the friction coefficient of composites without current was smaller than that with current. The contact voltage drop of composites was low in the initial state of wear and then rises to a certain level and remained constant.