發(fā)布時(shí)間：2018-01-20 16:39

  本文關(guān)鍵詞： 激光熔覆 原位自生 碳化鎢 鎳基復(fù)合涂層 耐磨性　出處：《廣東工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：金屬基陶瓷復(fù)合涂層既有金屬的強(qiáng)韌性,又有陶瓷材料良好的耐蝕性、耐高溫性、耐磨性和抗氧化性。采用原位自生技術(shù)制備金屬基陶瓷涂層,增強(qiáng)體可以在制備過程中通過原位反應(yīng)生成,增強(qiáng)體尺寸細(xì)小,分布彌散,表面無污染,與金屬基體浸潤性好,可改善增強(qiáng)體與粘接金屬之間的界面結(jié)合。本文研究了采用不同配比的Ni25/(WO3+C)復(fù)合粉體原位自生的涂層的微觀組織、物相組成、涂層脆性、顯微硬度、摩擦磨損等性能的變化規(guī)律,并深入分析了磨損機(jī)理。通過電子顯微鏡(SEM)、X射線衍射儀(XRD)、顯微硬度測(cè)試儀、WS-2005涂層附著力自動(dòng)劃痕儀、CFT-I型多功能材料表面綜合性能測(cè)試儀等儀器手段研究了涂層的組織和性能。研究結(jié)果表明：(1)涂層預(yù)置粉末的厚度選用1.5mm,最佳的工藝參數(shù)為：電流為300A,脈寬為1.6ms,頻率為30Hz,速度為2mm/s。稀釋率較低,涂層與基體熔覆良好表面光滑平整,宏觀形貌優(yōu)異,涂層厚度為200-300μm。(2)涂層的頂部組織大多為細(xì)小枝晶和細(xì)小等軸晶；涂層的中部為方向各異的樹枝晶和胞狀晶；底部為平面晶。枝晶的生長方向垂直于平界面,平行于激光熔覆的傳熱方向。復(fù)合涂層主要由(Fe)Ni固溶體、Cr7C3、 Cr23C6、 Fe3W3C、W2C、 WC等物相所構(gòu)成。WxC的大小約為0.5-2μmm,形態(tài)呈顆粒狀、長方形、三角形等狀。原位自生的WxC顆粒無缺陷,WxC內(nèi)部未發(fā)生開裂,且WxC與周圍基體結(jié)合良好。(3)涂層的硬度明顯高于基體的硬度；并且隨著(W03+C)含量增加,復(fù)合涂層的顯微硬度也逐漸上升。最高硬度達(dá)704HVo.2,約為基體的3.5倍。(4)相比45鋼基體,涂層的摩擦系數(shù)較低,當(dāng)復(fù)合粉體中(W03+C)含量低于40%時(shí),摩擦系數(shù)隨(W03+C)含量的增加而逐漸降低；(W03+C)含量上升到50%時(shí)摩擦系數(shù)反而上升。(WO3+C)含量為40%時(shí)摩擦系數(shù)與高鉻鑄鐵耐磨鋼Crl5Mo3的摩擦系數(shù)相近,取到了很好的減摩作用。(5)10%-30%(W03+C)的涂層的磨損區(qū)域存在一些凹坑和磨屑,主要磨損機(jī)理為粘著磨損和磨粒磨損；40%(WO3+C)和50%(W03+C)的涂層的磨損區(qū)域存在一些磨屑和微裂紋,磨損機(jī)理主要為磨粒磨損和脆性剝落。(6)利用激光輻照,在Ni25、WO3、Al和C粉末之間發(fā)生鋁熱反應(yīng)原位合成WxC復(fù)合涂層。反應(yīng)產(chǎn)物物相組成為WC、W2C、W3C、和Al2O3相,WxC相為白色顆粒狀,尺寸小于200nm,主要分布在(Fe)Ni固溶體的晶界上,也有部分分布在晶內(nèi)。熔覆層組織均勻致密、無裂紋和孔洞等缺陷,熔覆層與基體呈良好的冶金結(jié)合。熔覆層最高硬度為900HVo.2,是基體的4.5倍。
[Abstract]:The metal-based ceramic coatings were prepared by in-situ in-situ technique. The composite coatings not only have the strength and toughness of metals, but also have good corrosion resistance, high temperature resistance, wear resistance and oxidation resistance of ceramic materials. The reinforcements can be produced by in-situ reaction in the process of preparation. The reinforcements are fine in size, dispersed in distribution, free of surface pollution, and have good wettability with metal matrix. In this paper, the microstructure, phase composition and brittleness of in-situ Ni25/(WO3 C composite powder coating were studied. The variation of microhardness, friction and wear, and the wear mechanism were analyzed. The SEM X-ray diffractometer and the microhardness tester were used. WS-2005 coating adhesion automatic scratch instrument. The microstructure and properties of the coating were studied by means of CFT-I multifunctional material surface comprehensive performance tester and other instruments. The results showed that the thickness of the coating preset powder was 1.5mm. The optimum technological parameters are as follows: current is 300A, pulse width is 1.6 Ms, frequency is 30 Hz, speed is 2 mm / s. The dilution rate is low, and the surface of coating and substrate is smooth and smooth. The microstructure of the coating is mostly fine dendrite and fine equiaxed crystal. The central part of the coating is dendritic and cellular crystal with different directions. The growth direction of the dendrite is perpendicular to the flat interface and parallel to the heat transfer direction of laser cladding. The composite coating is mainly composed of Cr7C3 and Cr23C6. The size of Fe _ 3W _ 3C _ 2C _ 2C and WC is about 0.5-2 渭 mm. The shape of Fe _ 3W _ (3C) W _ (2C), W _ (2C), WC and so on is granular, rectangular and triangular. There is no defect in in-situ WxC particles. There was no cracking in WxC, and the hardness of WxC coating was obviously higher than that of substrate. With the increase of W03 C) content, the microhardness of the composite coating increases gradually, and the highest hardness is 704HVo.23.5 times as much as that of the substrate. The friction coefficient of the coating is lower, when the content of W03 C in the composite powder is lower than 40%, the friction coefficient decreases with the increase of W03 C content. When the content of W03 C increased to 50, the friction coefficient increased. When the content of WO 3 C was 40, the friction coefficient was similar to that of high chromium cast iron wear resistant steel Crl5Mo3. There are some pits and debris in the wear zone of the coating. The main wear mechanism is adhesive wear and abrasive wear. There are some debris and microcracks in the wear zone of the WO _ 3 C and 50 W _ 03 C) coatings. The wear mechanism is mainly abrasive wear and brittle spalling. WxC composite coatings were synthesized in situ by aluminothermic reaction between Ni _ (25) O _ (3) O _ (3) Al and C powders. The reaction products were composed of WCC _ (2) C _ (2) C _ (3) C and Al2O3 phase. The WxC phase is white granular with a size less than 200nm.It mainly distributes on the grain boundary of Fegni solid solution, and also has some distribution in the crystal. The microstructure of the cladding layer is uniform and dense, and there are no defects such as cracks and pores. The highest hardness of the cladding layer is 900HVo. 2, 4.5 times of that of the substrate.
【學(xué)位授予單位】：廣東工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG174.4

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