| Aluminum bronze has the excellent properties of copper alloy, and also has high strength, high hardness, high reducing friction and wear resistance, good resistance to corrosion, which often used in drawing die, the valve material, pressing mold, power plants and other modern technology in the field. However, with the development of science and technology, previous studies of some lower Al content of aluminum bronze alloy has been unable to meet the needs of today’s use, and found in the matrix of preparing aluminum bronze coating can effectively improve the performance of the work piece, which made the development of new high aluminum bronze coating has great practical significance. The solid solution treatment and aging treatment of aluminum bronze alloy can eliminate the residual stress and improve the properties and organization structure of the alloy. Therefore, how to strengthen the new type of high aluminum bronze coating has a significant value.In this paper, three kinds of high aluminum bronze thermal spraying coatings with different Al content were prepared on the 45 steel substrate by oxygen acetylene thermal spraying technology, and through the heat treatment to strengthen the coatings by the solid solution and aging treatment. This experiment through different solid solution treatment temperature and time, different cooling methods and different aging treatment temperature and time to influence on coating’s organization structure, micro-hardness and friction and wear properties to determine the optimum process conditions and be prepared with different contents of aluminum coatings. The inverted metallurgical microscope and scanning electron microscope (SEM) were used to characterize the organization structure, thickness and combination, EDS energy spectrum instrument and X-ray diffraction (XRD) were used to check coating’s phase structure, micro-hardness analysis meter measuring were used to characterize coating’s micro-hardness, surface comprehensive performance testing instrument were used to detect coating tribological characteristics and main conclusions are as follows:Solid solution treatment:Cu-10Al-X and Cu-15A1-X coating’s phase has changed at 600℃/0.5h solid solution treatment by air cooling and the hard phase was more than the others conditions, β phase(Cu3Al) was dissolved and generated it’s allotrope β martensite(Cu3Al2 phase), α-Cu phase was decreased relatively and generated a certain hard phase to strengthen coatings. Micro-hardness of the coatings has been improved, which Cu-15Al-X coatings lifting range were the biggest, and in 600℃/0.5h under the condition of solid solution treatment to obtain the obvious enhancement, micro-hardness improved from 159.15HV0.1 to 258.53HVo.i after solid solution treatment, which mainly strengthening mechanism were solid solution strengthening, strengthening phase transformation of martensite and surplus strengthening etc. Water coating strengthening effect less than air cooling coating.Aging treatment:Under the above conditions, the coatings’organization structure and properties after 400℃/1h aging treatment were better than other aging conditions. The coatings’main phase were α-Cu, γ2 phase represented by Cu9Al4 and Cu4Al, β phase(Cu3Al), such as Al65Cu2oFe15 K phase containing Fe element with hard and dense oxide film Al2O3 phase, little Cu3Al2 phase, Al-Ni phase (AINi3, Al4Ni3, etc.) and Cu2O, etc. These K phases were formed by diffusion of Fe into the coating in the 45 steel matrix. The coatings’morphology of hard phase performance have lots of black area, the Cu-15A1-X coatings’hard phase content were more than the other two kinds of coatings, increased more precipitation of Cu-Al phase, the maximum micro-hardness were 289.81 HV0.1. Three kinds of coatings main strengthening mechanisms were precipitation strengthening, phase transformation strengthening, excess phase strengthening, grain refinement, cooled coatings’ strengthening mechanisms after aging treatment were aging strengthening and surplus strengthening.Tribological properties of coatings:The test conditions for the friction and wear of the coatings were time of 15min, load of 50N, rotating speed of 500r/min and sliding distance of 5mm, which showed a good wear resistance, and better than other test conditions. (1) Friction and wear under dry friction:Heat treatment conditions for air cooling after 600 ℃/0.5h solution treatment,400℃/1h aging treatment, the minimum friction coefficient of the Cu-15Al-X coating was 0.42, which was less than the other two series of coating, coatings under solid solution after air cooling and coatings without heat treatment, the coatings friction were improved. The Cu-15Al-X coatings’ wear rate were the lowest in the three series of coatings, which were about 3.3×10-5mm3/Nm, which indicated that the wear resistance of the coatings were improved. The main wear forms were abrasive wear and adhesive wear. (2) Friction and wear under wet friction:The friction and wear resistance of the coatings were improved by adding lubricant under the same conditions of dry friction. The friction coefficient of Cu-15Al-X coatings decreased to 0.10, and the wear rate decreased to 0.18×10-5mm3/Nm. The main wear form we adhesive wear. |
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