本文選題：氧乙炔熱噴焊 + 風機葉片　； 參考：《陜西科技大學》2017年碩士論文

【摘要】：風機作為能源礦山等領域重要的輔助設備之一,其使用環(huán)境惡劣,葉片受腐蝕磨損嚴重。因此提高風機葉片的使用壽命,對企業(yè)的可靠、經濟運行有重要的意義。氧乙炔熱噴焊Ni基WC因設備簡單、適應性強、效果顯著,能夠在修復受損失效葉片的同時提高其耐磨耐蝕性能,提高使用壽命,降低生產成本。但是氧乙炔熱噴焊Ni基WC因自身設備及工藝特點,涂層易出現孔隙、夾雜、過熔及氧化等問題。本文在綜合國內外學者研究的基礎上,通過對比不同前處理方法、噴焊工藝參數及WC含量,分析其對涂層的表面沉積、組織缺陷、物相結構、顯微硬度、摩擦磨損及耐蝕性能方面的影響,并運用激光重熔及硼硅共滲來改善噴焊后的涂層組織,提高噴焊層的性能。結合實驗和測試分析結果,得到如下結論:(1)前處理可以提高噴涂粉末的沉積率,各因素的影響比重大小為:表面粗糙度噴涂距離預熱溫度,經優(yōu)化后火焰噴涂的沉積率為43.97%。微觀組織結構顯示噴涂粉末的沉積方式主要為球狀粘連和片層堆積,當片層堆積為主時涂層的效果最好。通過對失效后的風機葉片使用80目的砂紙毛化處理、表面清理、及300℃溫度下預熱處理后,使用含量35%WC的Ni基合金,用中性火焰在噴涂距離為10~15cm,重熔時間為4min,完成受損葉片的修復,獲得0.65mm厚冶金結合的Ni基WC噴焊層,通過微整形加工及噴漆后裝機再使用。(2)Ni基WC涂層主要以g-Ni及FeNi_3相為主,NiCrBSi-35%WC表面硬度為856HV,在距離涂層表面0.2mm左右時硬度值達到最大為921HV。WC比例較高時,WC容易因缺少Ni基層的保護,而使涂層表層的WC受熱影響脫碳,W元素分布均勻。而涂層內部的WC因分解較少,W元素分布呈現階梯性變化。W元素在基體中擴散,使C元素相分布集中,Cr3C2、(Cr,Fe)7C3以及(Cr,Fe)23C6等碳化物相增多,而Si、B相的含量在除氧造渣中因過氧化而減少。(3)當WC含量比例提高,雖然涂層的硬度增加,但涂層的孔隙和夾雜增多,出現粉末團聚現象問題也增多,而且直徑大于40mm的大孔隙多出現在粉末團聚處。WC含量大于35%時,涂層的磨損易使硬質相顆粒整體脫離,且耐腐蝕性能也較低,WC顆粒也更容易因基體被腐蝕而整體脫離,其中WC含量在30%~40%時耐磨性能較好。(4)重熔時間越長,WC的XRD衍射峰強越低,分解越嚴重,Cr3C2以及(Cr,Fe)23C6的峰強隨著重熔時間延長而增大,Ni_3B及Ni Si相的峰強隨重熔時間增加而降低,涂層的氧化越嚴重。重熔后涂層的摩擦系數在0.3~0.6區(qū)間波動,重熔2min時平均摩擦系數為0.45,4min時為0.31,重熔6min時為0.28。重熔時間越長,涂層表面越平整,孔隙度越低,但是過熔氧化的問題也越嚴重。(5)氧乙炔熱噴焊NiCrBSi-WC涂層的缺陷主要有:微縮孔、大孔隙、夾雜、凹凸面、過熔及氧化。通過激光重熔改性后氣孔、緊縮孔和夾雜減少,涂層整體較為平滑致密,2q=44°附近Ni2.9Cr0.7Fe0.36和FeNi_3的XRD主峰峰強明顯增高,(1 1 1)晶面上相位峰及51.4°和75.6°次強峰出現尖銳化,晶體呈等軸晶區(qū)生長,結晶度提高。激光的熱效應使Cr3C2、(Cr,Fe)7C3等碳化物相增多,硬度增大,表面硬度提高到909HV,平均摩擦系數降低至0.583。硼硅共滲使涂層的Ni_3B、NiSi等硼化物及硅化物相增多,摩擦系數進一步降低至0.428,抗磨損性能提高1.17倍。
[Abstract]:As one of the important auxiliary equipment in energy mines and other fields, the air fan is used in bad environment and the blade is corroded and worn seriously. Therefore, it is of great significance to improve the service life of the blade of the fan, and it is of great significance to the reliability and economic operation of the enterprise. The oxygen acetylene thermal spray welding Ni based WC has the advantages of simple equipment, strong adaptability and remarkable effect, and can be used to repair the loss effect leaves. The film can improve its wear resistance and corrosion resistance, improve the service life and reduce the cost of production. However, because of its own equipment and process characteristics, the coating of Ni based WC is easy to appear pores, inclusions, over melting and oxidation. On the basis of comprehensive research at home and abroad, the parameters of spray welding process and W are compared by comparing different pretreatment methods. The effect of C content on the surface deposition, microstructure defect, phase structure, microhardness, friction and wear and corrosion resistance of the coating was analyzed, and laser remelting and borosilicate were used to improve the structure of the coating after spray welding and improve the performance of the spray welding layer. The following conclusions were obtained by combining the experimental and test results: (1) pre treatment can improve the spray. The deposition rate of powder coating, the proportion of the influence of each factor is: surface roughness spraying distance preheating temperature, after optimization, the deposition rate of flame spraying is 43.97%. microstructure shows that the deposition of spray powder is mainly spherical adhesion and lamellar accumulation, when the layer accumulation is the best coating, through the failure after the failure. After 80 purpose sand paper hairy treatment, surface cleaning, and preheating treatment at 300 C, the fan blade uses a Ni base alloy with 35%WC content, using neutral flame at 10~15cm and remelting time of 4min to complete the repair of damaged blade, and obtain Ni based WC spray welding layer with 0.65mm thick metallurgical bonding, through micro plastic processing and after spray painting. (2) (2) the main Ni based WC coating is mainly g-Ni and FeNi_3, the surface hardness of NiCrBSi-35%WC is 856HV, the hardness of the coating is higher than that of the coating on the surface of the coating. When the maximum of the hardness is higher than the 921HV.WC ratio, WC is easy to avoid the protection of the Ni base, so that the WC heating shadow of the coating surface is decarbonization and the distribution of the W elements is uniform. The distribution of W elements is less, the distribution of W elements shows a step change, and the diffusion of.W elements in the matrix makes the phase distribution of C elements concentrated, Cr3C2, (Cr, Fe) 7C3 and (Cr, Fe) 23C6 and other carbides increase, while Si, the content of the B phase decreases because of peroxidation in deoxidization slag. (3) the increase in the proportion of the content, although the hardness of the coating increases, but the pores and inclusions in the coating increase The phenomenon of powder agglomeration is also increasing, and when the large pore size larger than 40mm is more than 35%, when the content of.WC in the powder agglomeration is more than 35%, the wear of the coating will easily disconnect the hard phase particles, and the corrosion resistance is low, and the WC particles are more easily disconnected because the matrix is corroded, and the wear resistance of the WC content in 30%~40% is more than that of the matrix. (4) the longer the remelting time, the lower the XRD diffraction peak of WC, the more serious the decomposition, the increase of the peak strength of Cr3C2 and (Cr, Fe) 23C6 with the prolongation of remelting time. The peak strength of Ni_3B and Ni Si phase decreases with the increase of remelting time, and the oxidation of the coating is more serious. The friction coefficient of the coating is fluctuated in the 0.3~0.6 interval and the average friction coefficient of the remelting 2min. For 0.45,4min 0.31, the longer the remelting time for remelting 6min, the longer the 0.28. remelting time, the more smooth the coating surface and the lower the porosity, but the more serious the problem of the oxidation is. (5) the defects of the oxygen acetylene thermal spray welding are mainly micro shrinkage holes, macropores, inclusions, concave and convex surfaces, over melting and oxidation. The pores, holes, and clips after remelting by laser remelting are used. The coating overall is more smooth and compact, the peak intensity of XRD peak in Ni2.9Cr0.7Fe0.36 and FeNi_3 near 2q=44 degree is obviously increased. (111) the phase peak and the 51.4 degree and 75.6 degree peak of the crystal face sharpening, the crystal growth and the crystallinity increase. The thermal effect of the laser increases the carbide phase, such as Cr3C2, (Cr, Fe) 7C3, and the hardness increase. The surface hardness is increased to 909HV, the average friction coefficient is reduced to 0.583. borosilicate, and the Ni_3B, NiSi and other borides and silicides in the coating increase, the friction coefficient is further reduced to 0.428, and the wear resistance is increased by 1.17 times.
【學位授予單位】：陜西科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG174.4

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本文編號：1979318