Study On The Fabrication Processes And The Antibacterial Property Of Copper-added Gray Cast Iron

Gray cast iron is an indispensable raw material for the mechanical industry because of its good combination of castability,vibration damping and machinability.By adding appropriate amount of copper to gray cast iron and subsequent appropriate heat treatment,certain antibacterial properties can be obtained,but the addition of copper and heat treatment will affect the antibacterial properties of the material as well as other properties such as corrosion resistance and mechanics.Therefore,it is important to select the appropriate amount of copper addition and heat treatment process to prepare an overall antibacterial material with excellent corrosion resistance and mechanical properties.In this study,five gray cast iron materials with Cu contents of 0%,1.2%,2.0%,2.8%and 3.6%(mass fraction)were prepared by vacuum electric arc melting furnace.The microstructure and morphology of the cast,aged at 530°C and aged at 730°C gray cast iron were observed by metallographic microscopy and scanning electron microscopy analysis;the elemental distribution and phase composition were examined by energy spectrometer and X-ray diffractometer;the effects of Cu content and heat treatment process parameters on the hardness,The effect of copper content and heat treatment process parameters on the hardness,wear properties,compressive properties and corrosion properties of the prepared gray cast iron was investigated by means of Brinell hardness tester,friction and wear tester,universal tester and electrochemical workstation.The results of microstructure analysis showed that the addition of Cu helped to enhance the percentage of pearlite organization in the gray cast iron,while refining the pearlite lamellae spacing.No obvious Cu single phase was observed in the as-cast and Cu-added gray cast iron in the aging state at 530°C,while in the aging state of Cu-added gray cast iron at 730°C,Cu obviously aggregated and precipitated at grain boundaries,forming nanoscale Cu-rich phases.The results of hardness and wear resistance tests showed that the hardness and wear resistance of gray cast iron increased with the increase of Cu addition;compared with the as-cast state,the hardness and wear resistance of gray cast iron with the same Cu content decreased correspondingly with the increase of aging temperature.Compression experiments show that the addition of Cu improves the compressive strength of gray cast iron,with the highest compressive strength at 2.0 wt.%.The improvement in mechanical properties is mainly the result of grain refinement.The corrosion resistance results show that the addition of Cu appropriately improves the corrosion resistance of gray cast iron,with the best corrosion resistance at 730°C aging state and the worst corrosion resistance at 530°C aging state,which is obviously the result of the precipitation of Cu phase changing the self-corrosion current density.The results of the antibacterial experiments showed that the addition of Cu enhanced the antibacterial rate of E.coli in gray cast iron,and the antibacterial effect of Cu-added gray cast iron in cast state and Cu-added gray cast iron in 530°C was average.The antibacterial effect of 730°C Cu-added gray cast iron was significantly improved,and the antibacterial rate was up to 99.99% after 6h contact sterilization,which can be attributed to the aggregation and precipitation of nanoscale Cu-rich phase at the grain boundary.In summary,the addition of Cu promoted the formation of pearlite structure in the gray cast iron matrix,refined the matrix structure,and improved the mechanical properties and corrosion resistance of the gray cast iron.nano-scale Cu-rich phase precipitated at the grain boundaries in the Cu-added gray cast iron in the aging state at730°C,which significantly improved the antibacterial properties of the Cu-added gray cast iron.