【摘要】：鉆井泵作為鉆井系統(tǒng)的核心,其能否正常工作關(guān)系整個(gè)鉆井過程。鉆井泵中最容易損傷的零部件為缸套,進(jìn)入柱塞與缸套之間的硬質(zhì)顆粒在運(yùn)動(dòng)過程中會(huì)對(duì)缸套內(nèi)壁造成磨損,其磨損機(jī)制主要是磨粒磨損。激光熔覆制備Ni基WC涂層可以將合金良好的韌塑性能與陶瓷的耐磨性能結(jié)合在一起。但WC與Ni基合金的物相差異,使熔覆層中存在較大的應(yīng)力,最終導(dǎo)致熔覆層的開裂。制備梯度涂層可以緩解熔覆粉末與基體之間因物相差異所導(dǎo)致應(yīng)力集中。本文主要通過激光熔覆的方式來制備高含量WC鎳基涂層。通過優(yōu)化激光熔覆工藝參數(shù),引入CaF2和Ni35過渡層來有效解決裂紋問題。利用掃描電鏡觀察熔覆層的微觀組織,測試其力學(xué)性能,最終得到性能良好的超硬熔覆層。研究結(jié)果表明,單道熔覆層中隨著WC含量的增加,熔覆層的裂紋率先升高后下降,在WC含量為30%左右時(shí)達(dá)到最大值;為保證熔覆層的成型性和耐磨性能,最終確定SD-Ni45作為基礎(chǔ)熔覆材料,其最佳工藝參數(shù):激光熔覆功率3500W,掃描速度100mm/min;通過對(duì)超硬涂層的微觀組織和物相分析可知超硬涂層中主要包括WC和碳化物以及樹枝狀組織γ-Ni,由于熔覆層中含有較多的WC,其顯微硬度可達(dá)2000HV0.1。在超硬涂層中添加5%CaF2可以改善熔覆層的表面成型,同時(shí)CaF2密度低在激光熔覆過程中向熔覆層表面運(yùn)動(dòng),對(duì)熔池起到攪拌的作用促進(jìn)WC在熔覆層中均勻分布,這種組織和硬質(zhì)相的均勻分布使其顯微硬度有所下降僅有1500HV0.1,但其耐磨性有明顯提高;在超硬涂層與基體之間增加一層Ni35過渡層可以緩解因超硬涂層與基體物相差異而產(chǎn)生的應(yīng)力集中,同時(shí)Ni35過渡層顯微硬度介于二者之間避免了熔合區(qū)處顯微硬度的陡降,使整個(gè)熔覆層的顯微硬度過渡平緩。最終得到了成型良好、無裂紋且組織致密的梯度涂層。
[Abstract]:As the core of drilling system, the drilling pump is the core of the drilling system. The most easily damaged parts in the drilling pump are cylinder sleeve. The hard particles between the plunger and the cylinder sleeve will wear out on the inner wall of the cylinder liner during the movement process. The wear mechanism is mainly abrasive wear. The laser cladding is used to prepare the Ni based WC coating. The good toughness and ductility of the alloy are combined with the wear resistance of the ceramics. But the difference between the WC and the Ni based alloys makes the cladding layer more stress and eventually leads to the cracking of the cladding layer. The preparation of the gradient coating can relieve the stress concentration in the difference between the powder and the matrix. This paper mainly through laser cladding. The high content WC nickel base coating was prepared by the method of optimizing the laser cladding process parameters and introducing the transition layer of CaF2 and Ni35 to solve the crack problem effectively. The microstructure of the cladding layer was observed by scanning electron microscope, and the mechanical properties of the cladding layer were tested. Finally, the super hard cladding layer was obtained. The results showed that the content of WC in the single channel cladding layer was with the content of the cladding. The cracks in the cladding layer first rise and then decrease and reach the maximum when the content of WC is about 30%. In order to ensure the formability and wear resistance of the cladding layer, the SD-Ni45 is finally determined as the basic cladding material, and the optimum technological parameters are the laser cladding power 3500W, the scanning speed 100mm/min, and the microstructure and phase separation of the superhard coating. It is known that the superhard coatings mainly include WC, carbide and dendritic tissue gamma -Ni. Because of the more WC in the cladding layer, the microhardness of the coating can reach 2000HV0.1. in the superhard coating by adding 5%CaF2 to improve the surface formation of the cladding layer. At the same time, the density of CaF2 is low in the laser cladding process to the surface of the cladding layer, and the weld pool is stirred. The mixing effect promotes the uniform distribution of WC in the cladding layer. The uniform distribution of the microstructure and hard phase makes the microhardness decrease only 1500HV0.1, but its wear resistance is obviously improved, and a layer of Ni35 transition layer between the superhard coating and the matrix can relieve the stress concentration caused by the difference between the superhard coating and the matrix, and N The microhardness of the i35 transition layer between two avoids the steep drop of microhardness at the fusion zone and the transition of the microhardness of the whole cladding layer slowly. Finally, a gradient coating with good shape, no crack and dense tissue is obtained.
【學(xué)位授予單位】：中國石油大學(xué)(華東)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG174.453

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本文編號(hào)：2138769