本文關(guān)鍵詞： 雙絲電弧噴涂 Ni-Al涂層 6061-T6鋁合金 顯微結(jié)構(gòu) 力學(xué)性能　出處：《哈爾濱工業(yè)大學(xué)》2015年博士論文　論文類型：學(xué)位論文

【摘要】：本文根據(jù)大型船舶偏流板服役特點,研究了雙絲電弧噴涂(TWAS)Ni-Al涂層制備及性能問題,并對TWAS過程進(jìn)行了研究。利用VOF雙相流模型和標(biāo)準(zhǔn)k-ε模型,分析了不同直徑熔滴在不同霧化氣體壓力下的變形和破碎過程,以及Weber數(shù)對熔滴破碎過程的影響。同時對不同速度的熔滴撞擊基體的變形和凝固溫度場進(jìn)行了詳細(xì)分析,揭示了TWAS噴涂粒子速度的氣體飛行動力學(xué)規(guī)律�；诓煌愋偷耐繉又苽浞椒ê凸に�、涂層結(jié)構(gòu)和材料的耦合制備了多種結(jié)構(gòu)涂層,明晰了不同的噴涂工藝參數(shù)與TWAS過程中噴涂粒子尺寸間的關(guān)系。在結(jié)合強(qiáng)度、摩擦系數(shù)及耐磨性初步分析基礎(chǔ)上,對各種涂層結(jié)構(gòu)進(jìn)行了全面的性能分析,研究了顯微硬度、結(jié)合強(qiáng)度、耐沖擊、耐高溫和耐腐蝕等特性與涂層結(jié)構(gòu)的關(guān)系。對所獲最優(yōu)Ni-Al復(fù)合涂層的顯微結(jié)構(gòu)、表面粗糙度和耐磨性能進(jìn)行了系統(tǒng)研究。分析了不同熱處理工藝對Ni-Al涂層顯微組織和相結(jié)構(gòu)的影響,討論了涂層與鋁合金基體界面反應(yīng)機(jī)理,以及基體和涂層之間的界面元素擴(kuò)散行為。獲得以下結(jié)果:采用雙絲電弧噴涂和火焰噴涂在6061-T6鋁合金基體上制備Ni-5wt.%Al、Ni-20wt.%Al、Ni-30wt.%Al單層結(jié)構(gòu)、Ni-5wt.%Al//Ni-5wt.%Al、Ni-5wt.%Al//Ni-20wt.%Al、Ni-5wt.%Al(Arc)//Al包Al2O3(Arc)、Ni-5wt.%Al(Arc)//Al包Al2O3(Flame)雙層結(jié)構(gòu)、Ni-5wt.%Al//Zn//Ni-5wt.%Al、Ni-5wt.%Al//Zn//Ni-20wt.%Al三明治結(jié)構(gòu)等九種不同結(jié)構(gòu)涂層,根據(jù)結(jié)合強(qiáng)度、耐高溫、耐沖蝕性、抗熱沖擊、抗加速腐蝕、化學(xué)溶液耐受性和鹽霧腐蝕等性能進(jìn)行對比分析,確定了金屬基涂層的成分和結(jié)構(gòu),即以Ni-5wt.%Al為打底層和Ni-20wt.%Al作為面層的復(fù)合涂層結(jié)構(gòu)。雙絲電弧噴涂熔滴破碎形式為一次破碎和二次破碎形式及爆炸式破碎形式。Weber數(shù)與霧化氣體壓力呈近似線性關(guān)系。在一定范圍內(nèi)變化時,增大噴涂霧化空氣壓力可以提高熔滴飛行速度,改善熔滴霧化效果。熔滴的形態(tài)、凝固層變化和溫度場變化一致,并獲得了熔滴冷卻速度范圍為3.1×107~7.6×107K/s。TWAS噴涂粒子速度的氣體飛行動力學(xué)計算和分析結(jié)果表明,TWAS噴涂粒子在霧化氣體中的初始加速較快,然后趨于平緩和穩(wěn)定。當(dāng)噴涂粒子加速飛行距離為200mm,且粒子的粒度范圍為5μm~50μm時,噴涂粒子的飛行速度僅能達(dá)到初始?xì)饬魉俣鹊?5%~45%。Ni-5wt.%Al涂層中的主相為Ni固溶體,還包括少量Al2O3、Ni O和Ni3Al4;Ni-20wt.%Al涂層中的主要組成相為Ni固溶體、Ni Al和Ni3Al。TEM分析表明:在原始態(tài)Ni基體上形成細(xì)小的球形Ni3Al析出相,同時存在非晶相和等軸晶,均系噴涂粒子在極快的冷卻過程中形成。經(jīng)過電子探針能譜分析,涂層主要由Ni、Al和O等元素構(gòu)成。Ni-Al涂層具有較高的結(jié)合強(qiáng)度、硬度、粗糙度和較大的靜摩擦系數(shù)。Ni-20wt.%Al涂層表現(xiàn)出較好的耐磨性,200個循環(huán)磨損后,濕態(tài)靜摩擦系數(shù)大于干態(tài)靜摩擦系數(shù),涂層在整個磨損過程中始終表現(xiàn)為粘著磨損。激光共聚焦顯微鏡分析結(jié)果表明:隨著噴涂距離和噴涂空氣壓力減小,Ni-Al涂層的表面粗糙度增大,但隨著噴涂距離的減小,噴涂空氣壓力影響減弱。Ni-Al涂層經(jīng)400℃~550℃/4h~48h熱處理后,相組成變化較小。根據(jù)Miedema理論模型,涂層/基體界面發(fā)生擴(kuò)散,形成金屬間化合物Ni Al3,隨著熱處理溫度升高和時間的延長,在Ni Al3相和涂層之間形成Ni2Al3相,同時界面擴(kuò)散區(qū)逐漸增厚,該過程由Al原子的擴(kuò)散所控制。熱處理后的TEM分析表明:涂層中存在Ni Al3、Ni2Al3及Ni的退火孿晶相。根據(jù)在400℃、480℃和550℃溫度不同時間的小角衍射結(jié)果,Ni-Al合金擴(kuò)散動力學(xué)符合3次方規(guī)律,根據(jù)S.Arrhenius公式,建立高溫原子擴(kuò)散模型,計算出晶粒的長大指數(shù)n值均在0.25~0.35之間,與理論推導(dǎo)關(guān)系x2∝t1-n一致。在特定工藝條件下,較高的噴涂壓力易于產(chǎn)生較小的噴涂粒子,適合作為Ni-Al復(fù)合涂層的打底層,而相對較低的噴涂壓力產(chǎn)生相對較大的噴涂粒子,更適合作為偏流板涂層的面層。
[Abstract]:According to the large ship drift plate serving features, the twin wire arc spraying (TWAS) preparation and properties of Ni-Al coating, and the process of TWAS was studied. K- model and standard k-e model for two phase flow using VOF, analyzes the different diameter of the droplet in different atomizing gas pressure under the process of deformation and breakup. And the influence of Weber number on the droplet breakup process. At the same time on different speed of droplets impinged on the substrate deformation and solidification temperature field are analyzed in detail, reveals the gas particle velocity flight dynamics TWAS. The method and technology of preparing coating based on a variety of different types, structure of coatings coating structure and coupling the relationship between spraying materials, particle size between the clarity of the different spraying parameters and TWAS process. In the preliminary analysis of bonding strength, friction coefficient and wear resistance on the basis of various coating structure A comprehensive performance analysis of microhardness, adhesion strength, impact resistance, high temperature resistance and the relationship between corrosion resistance and coating structure. To obtain the optimal Ni-Al microstructure of the composite coating, surface roughness and wear resistance were studied. Analysis of the effect of different heat treatment process and phase structure of Ni-Al the coating microstructure, interfacial reaction mechanism of coating and Aluminum Alloy is discussed, and the interface element between the coating and the substrate diffusion behavior. The following results were obtained: by double wire Ni-5wt.%Al was prepared in the 6061-T6 Aluminum Alloy base on arc spraying and flame spraying Ni-20wt.%Al, Ni-30wt.%Al, Ni-5wt.%Al//Ni-5wt.%Al, Ni-5wt.%Al//Ni-20wt.%Al, single layer structure, Ni-5wt.%Al (Arc) //Al Al2O3 (Arc), Ni-5wt.%Al (Arc) //Al Al2O3 (Flame) Ni-5wt.%Al//Zn//Ni-5wt.%Al, Ni-5wt.%Al double layer structure, //Zn//Ni-20wt.%Al sandwich structure etc. Nine different structures according to the coating, bonding strength, high temperature resistance, erosion resistance, thermal shock resistance, accelerated corrosion, comparative analysis of chemical solution resistance and salt fog corrosion, determine the composition and structure of coatings on metals, i.e. Ni-5wt.%Al layer and Ni-20wt.%Al as composite coating surface layer. Twin wire arc spraying droplet breakage form of a broken and two crushing forms and shattered form.Weber number and atomization pressure is approximately linear. Changes within a certain range, increasing the spray air pressure can increase the droplet flight speed, improve the droplet atomization effect. The droplet morphology, consistent the solidified layer changes and temperature changes, and obtained the droplet cooling speed range for the calculation and analysis results of gas dynamics flight 3.1 * 107~7.6 * 107K/s.TWAS particle velocity shows that the spray particles TWAS In the initial atomization gas in accelerating faster, and then slow and stable. When the spray particle acceleration flight distance is 200mm, and the particle size range is 5 m~50 m, 15%~45%.Ni-5wt.%Al coating particles flying speed can only reach the initial air velocity in the main phase of Ni solid solution, also includes a small amount Al2O3, Ni, O and Ni3Al4; mainly composed of Ni-20wt.%Al phase in the coating is Ni solid solution, Ni Al and Ni3Al.TEM analysis showed that the formation of fine spherical Ni3Al precipitates in the original state of the Ni matrix, and existence of amorphous and equiaxed crystal, were sprayed particles in the cooling process of fast formation. After EPMA analysis, the coating is mainly composed of Ni, Al and O combined with strength, the elements of.Ni-Al coating with high hardness, roughness and large coefficient of.Ni-20wt.%Al coating showed better wear resistance of static friction, 200 cycle wear, wet The static friction coefficient is larger than the state of dry friction coefficient in the coating wear process was adhesive wear. Laser confocal microscopy analysis showed that with the spraying distance and spraying air pressure decreases, the surface roughness of Ni-Al coatings increased, but with the spraying distance decreases, spraying air pressure effect of.Ni-Al coating was decreased 400 DEG ~550 DEG /4h~48h after heat treatment, the phase composition changed little. According to the theory of Miedema model, the coating / substrate interface diffusion, formation of intermetallic compound Ni Al3, with the increase of heat treatment temperature and time, Ni2Al3 phase is formed between Ni Al3 and coating, while the interface diffusion zone gradually thickening, the process control the diffusion of Al atoms. After heat treatment, TEM analysis showed that Ni Al3 coating, Ni2Al3 and Ni of the annealing twins. According to 400 degrees, 480 degrees and 550 degrees at the same time, the temperature is not small Angle diffraction results accord with the 3 power law of Ni-Al alloy diffusion dynamics, according to the S.Arrhenius formula, a high temperature atomic diffusion model, calculated the grain growth index n value was between 0.25~0.35, and the relationship between x2 / t1-n theory. Under specific conditions, high pressure spraying easy to spray particles with smaller, suitable for as a base layer of Ni-Al composite coating, and spraying pressure is relatively low to produce spray particles relatively large, more suitable for the surface layer drift plate coating.

【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TG174.4

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