本文選題：工程機械 + 熱噴涂�。� 參考：《天津大學》2012年碩士論文

【摘要】：由于資源的日益短缺，產品利潤空間的不斷壓縮，以及潛在巨大市場的刺激，再制造成為工程機械行業(yè)的一個必然趨勢。熱噴涂技術作為一種高效便捷的表面修復技術，有望在工程機械再制造過程中得以廣泛地應用。 本文以裝載機變速箱二軸、三軸及驅動橋十字軸為例，，研究了工程機械軸類零件的失效機理。研究結果表明，工程機械軸類零件的主要失效方式為磨損失效，其磨損過程可以分為摩擦磨損－磨粒磨損－粘著及疲勞磨損三個階段。磨粒磨損過程中的硬質磨粒是由摩擦磨損過程中產生的磨屑在工件進一步運行的過程中逐漸形成的，硬質磨粒的形成大大加速了工件的磨損失效過程。 采用含有亞微米級WC顆粒的WC-12Co粉末，對裝載機變速箱齒輪二軸、三軸及驅動橋十字軸進行了HVOF再制造。采用的參數為：C_3H_8（0.75MPa，25L/min）、O（20.75MPa，250L/min）、N（20.6MPa，13L/min，2r/min）、噴管（150mm）、噴涂距離（265mm）。通過XRD、SEM、顯微硬度計等測試手段，對再制造涂層的表面質量進行了綜合評定，結果表明涂層主要由WC相與Co相組成，同時含有少量的W_2C；涂層的顯微硬度為1107HV_(0.1)；孔隙率為2.2%；涂層的平均抗拉強度為68.12MPa，最高達75.82MPa；涂層的主要斷裂機制為沿晶斷裂。 為了降低熱噴涂再制造成本，研發(fā)新的耐磨涂層，采用大氣等離子噴涂技術（APS），探索了碳納米管增強鐵基非晶合金復合涂層的制備工藝，并通過對扁平粒子和涂層斷面形貌的分析，研究了涂層的微觀結構。結果表明碳納米管的加入，可以通過“橋連”和“拔出”機制，對鐵基非晶合金涂層進行強化和韌化。但由于碳納米管的潤濕性比較差，致使其與鐵基非晶合金之間的結合不夠充分；同時等離子噴涂過程中，碳納米管的燒蝕比較嚴重，降低了碳納米管的纖維增強作用，因此還有待進一步的研究。 為了解決工程機械軸類零件表面的局部修復難題，對熱噴涂的工裝系統(tǒng)進行了再制造性設計，發(fā)明了一種熱噴涂再制造工裝及其自動修復控制系統(tǒng)，可以現實工程機械軸類零件局部表面精確、自動的熱噴涂再制造過程。
[Abstract]:Due to the increasingly shortage of resources, the continuous compression of product profit space and the stimulation of potential huge market, remanufacturing has become an inevitable trend in the construction machinery industry.As an efficient and convenient surface repair technology, thermal spraying technology is expected to be widely used in the remanufacturing process of construction machinery.In this paper, the failure mechanism of shaft parts of construction machinery is studied by taking two shafts, three shafts and drive axle cross shafts of loader gearbox as examples.The results show that the main failure mode of shaft parts of construction machinery is wear failure, and the wear process can be divided into three stages: friction and wear, abrasive wear, adhesion and fatigue wear.The hard abrasive particles in the process of abrasive wear are formed gradually during the further operation of the workpiece, and the formation of the hard abrasive particles greatly accelerates the wear failure process of the workpiece.The WC-12Co powder containing submicron WC particles was used to remanufacture the two shafts, three shafts and the drive axle cross shafts of the gearbox gears of the loader.The parameters used are: 10% C3HS 8 / 0.75 MPa / 25L / min / min / min / min / 0. 75 MPA / 250 L / min / min / / min / min / 0. 6 MPA / 13L / min / 2 r / min / min, 150 mm / min nozzle, and a spray distance of 265mm / min.The surface quality of the remanufactured coating was evaluated by means of XRDX SEM and microhardness tester. The results show that the coating is mainly composed of WC phase and Co phase.The coating contains a small amount of W2C; the microhardness of the coating is 1107 HVS 0.1; the porosity is 2.2; the average tensile strength of the coating is 68.12 MPA and the maximum is 75.82 MPA; the main fracture mechanism of the coating is intergranular fracture.In order to reduce the cost of thermal spray remanufacture, a new wear-resistant coating was developed. The preparation process of carbon nanotube reinforced Fe-based amorphous alloy composite coating was investigated by using atmospheric plasma spraying technique.The microstructure of the coating was studied by analyzing the morphology of the flat particles and the section of the coating.The results show that the Fe-based amorphous alloy coatings can be strengthened and toughened by the addition of carbon nanotubes through the mechanisms of "bridging" and "pulling out".However, because of the poor wettability of carbon nanotubes, the bonding between carbon nanotubes and Fe-based amorphous alloys is not sufficient, and the ablation of carbon nanotubes is serious during plasma spraying, which reduces the fiber reinforcement of carbon nanotubes.Therefore, further research remains to be done.In order to solve the problem of local repair of shaft parts of construction machinery, the remanufacturing design of thermal spraying equipment system was carried out, and a thermal spraying remanufacturing tool and its automatic repair control system were invented.The local surface of shaft parts of construction machinery can be accurately and automatically remanufactured by thermal spraying.
【學位授予單位】：天津大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH16

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