| High aluminum bronze alloy material of Al content more than11.8%which is Cu-Al alloy eutectoid point possess high hardness, good antifriction performance. A kind of high aluminum bronze of w (Al)=14%has been developed successfully by our research group, which has very good antifrictionability, wear resistance and corrosion resistance performance, and has been successfully applied to stretch die and stamping die.But the material performance is brittle, and it has the defects such as cracking and high cost as a whole material application. Should this material be developed to powders, and be prepared to surface protection coating of the matrix by advanced coating preparation technologies, it has the important meaning to broaden the scope of the use of material and to realize the surface protection and repair of workpiece. In addition, because the high aluminum bronze alloy powders not belong to the self-fluxing and is easy oxidation materials, the development research will have an important impact on the surface engineering development further.In this paper,a multiple high aluminum copper alloy materials of w(Al)=14%was configured and smelted by the combined scheme use of common pack a smelting, chemical refining by chloride, preliminary deoxidizing and final deoxygenation process. The alloy powders materials was prepared by the double-stage coupled and fast-setting of low vacuum atomized powder preparation technology. The main composition of the material is w(Cu)=70%～80%,w(Al)=12%～16%,w(Fe)=2.0%～4.0%,and the other trace elements such as Mn, Ni, Co, which is adjustable.The medium and small size of the powders more than70%can been achieved in the atomization pressure of3～8Mpa, and the liquidity of the powders is high to23.9/s.(50g)-1, the apparent density is low to3.56/g.cm-3and the average vickers microhardness reached384HV. The melting point of the alloy powders is1048℃, and the material belong to the soft magnetic materials, its initial permeability about μi=1.24.A kind coating preparation method of supersonic plasma-induction remelting composite technology was put forward to prepare high aluminum bronze alloy material coating in45#steel matrix surface.First of all,the powders coating of different particle size of high pure aluminum copper alloy was prepared through the supersonic plasma spraying technique.The X-ray diffraction (XRD), electron probe (EPMA), field emission scanning electron microscopy (FEGSEM) and spectrometer (EDS),image-proplus analysis software, Jade5.0software were used to analysis structure, physical phase composition,phase structure distribution, defect rate, and related mechanical properties of pure high aluminum bronze alloy powder coatings. At last,the best spraying powders particle size was achieved.The study found that the coating structure compact, the element segregation degree is low, and the component distribution uniformity, and the interface bonding is good prepared by super fine powders of surpassing400mesh.The defect rate and defect average area existed in the coating decreased with spraying powders granularity increase, and the defect rate has been reduced to the quite low level about1.27%using the more than400mesh powders, at the same time, the defect average area is0.40μm2. It is thus clear that the super fine aluminium bronze alloy powders of more than400mesh has better adapt ability to prepare the supersonic plasma spraying coating.Secondly, the different content of rare earth element Ce powders was joined to the best particle size powders(more than400meshes)of high aluminum bronze alloy, and the modified high aluminum bronze alloy powders coating was preparated after mixed rare earth Ce.The best addition amount of rare earth was achieved through the related organization structure and performance research.The results showed that the joined trace rare earth elements has a significant influence to the spraying coating organization structure,whose grain size is more refined, the organization structure is more fine uniform,and interface bonding status is markedly improved with the increase of the addition amount of rare earth elements. The trace rare earth elements can inhibit composition segregation of alloy, change the phase distribution form of coating, making the organization structure of the coating form from the non-equilibrium mode into equilibrium mode in the process of solidification.The defect rate of the coating reduced significantly when the rare earth was added to more than0.4%,which is less than the coating before adding rare earth. The coating hardness is reduced after added rare earth elements, accordingly, the comprehensive mechanics performance is improved, and the dispersion performance of the coating hardness is decreased. When the content of Ce is0.55%, it is not obvious to the hardness dispersion performance of the coating. So,the result can be concluded that the best addition amount of rare earth is between0.4%and0.55%.Finally, the high aluminum bronze alloy powders coating added the rare earth0.55%was remelted using induction remelting treatment technique for the coating optimization.The result showed that the density of the coating structure is obviously improved and the defect rate of the coating is decreased by rare earth modification and induction remelting process,and the combining state is greatly improved, forming a metallurgical bonding appeared white light about10～15μm in the interface place, which improve greatly the bonding strength of the coating and substrate, making the shear strength is improved12.7times relative to the coating before induction. The induction remelting can make coating defect change from large size into the small size, reducing the bad effect of the defect of local concentration on the coating performance.The induction remelting treatment make the coating hardness value slightly rebounded, and hardness dispersion performance reduce further.The wear-resisting performance was tested about the pure high aluminum bronze alloy coating, rare earth modification coating and induction remelting coating by the MMW-1universal friction and wear test machine.The results showed that the friction coefficient of the three kinds of coatings are all in a relatively low level in the dry friction condition, which is less than0.20.The coefficient of friction under high load540N is only1/10of low load100N, indicating the coating has the ability to bear friction and wear under high load. The friction coefficient of the coating after induction remelting is significantly lower than the coating before induction remelting, indicating the coating by induction remelting process has better wear resistance ability under high load.The wear mechanism are basic similar about the three kinds of coatings, which is mainly abrasive wear and adhesive wear, but has slightly different form under different load. The pure high aluminum bronze alloy powders coating made supersonic plasma spraying show the minor scratches in low load,but the abrasive wear characteristics is obvious under the high load, and have obvious adhesion and plastic deformation trace in the local. The coating through rare earth modification have occurred plastic deformation in low load, but the grinding crack morphology is uniform, having the abrasive wear characteristics.Under high load, the arrangement of surface grinding crack is very neat, appearing more deeply and more narrow furrow, and furrow edge can’t see lorate and hunched characteristics, indicating abrasive wear form mainly. The coating after induction remelting is given priority to scart wear and abrasive wear in low load, but the form show abrasive wear mainly along with the load increase, whose grinding mark is clear and neat, showing a better wear resistance and the stability of friction performance with the load change. |
PDF Full Text Request