王應(yīng)泉,房立家,淡焱鑫,3,吳雙杰,3,周平,3,黃晶,3,李華,3
電弧噴涂碳纖維增強鋁基耐蝕減磨復合涂層研究
王應(yīng)泉1,2,3,房立家1,淡焱鑫1,3,吳雙杰1,3,周平1,3,黃晶1,3,李華1,3
(1.中國科學院寧波材料技術(shù)與工程研究所,浙江 寧波 315201;2.中國科學院大學,北京 100049;3.中國科學院寧波材料技術(shù)與工程研究所寧波慈溪生物醫(yī)學工程研究所,浙江 慈溪 315300)
制備耐蝕減磨性能優(yōu)異的碳纖維增強鋁基復合涂層。利用粉芯絲材技術(shù)制備碳纖維增強鋁基復合粉芯絲材,再利用電弧噴涂技術(shù)將制備的復合粉芯絲材制備成復合涂層。對鋁基涂層使用SEM、XRD進行微觀形貌、物化性能檢測,使用摩擦磨損試驗機、電化學工作站、中性鹽霧試驗機等對涂層的摩擦學、耐腐蝕性能等進行檢測,綜合評價在涂層體系中添加碳纖維對鋁基涂層性能的影響。添加碳纖維的鋁基復合涂層相較于純Al涂層,其摩擦學性能得到顯著提升,摩擦系數(shù)由純Al涂層的~0.4下降至~0.2,磨損率由純Al涂層的~2.0×10–3mm3/(N·m)下降至~8×10–4mm3/(N·m),相關(guān)指標均下降了50%以上。同時,利用掃描電子顯微鏡觀察涂層表面的磨痕及對磨副的劃痕,并分析了鋁基涂層的磨損機理,結(jié)果表明,Al/CFs復合涂層主要以磨粒磨損為主導機制,而純Al涂層則以粘著磨損為主導機制。通過電化學工作站測試涂層的動電位極化曲線和Bode曲線分析涂層發(fā)生腐蝕的趨勢,其電化學結(jié)果表明,添加碳纖維后不顯著影響鋁基涂層的耐腐蝕性能。進一步中性鹽霧試驗結(jié)果表明,中性鹽霧試驗720 h后,鋁基涂層均未出現(xiàn)明顯的腐蝕產(chǎn)物,涂層展現(xiàn)了優(yōu)異的耐腐蝕性能。利用粉芯絲材技術(shù)和電弧噴涂技術(shù)可以制備碳纖維增強鋁基復合粉芯絲材及其涂層,在不影響原有鋁涂層耐腐蝕性能的前提下,添加碳纖維可顯著降低復合涂層的摩擦系數(shù)和磨損率,使涂層具有耐蝕減磨性能,可拓展鋁基涂層在耐蝕減磨領(lǐng)域中的應(yīng)用。
粉芯絲材;碳纖維增強;減磨;耐腐蝕;電弧噴涂;復合涂層
隨著世界工業(yè)的快速發(fā)展,油氣等資源的需求量迅猛增長,深海油氣資源的開采是海洋經(jīng)濟的重要方向之一[1]。但深海油氣資源的開采面臨著系列問題,海洋環(huán)境的“腐蝕”是面臨的最大挑戰(zhàn)。海洋環(huán)境是十分苛刻的服役環(huán)境,海洋工程無疑會遭受嚴重的腐蝕問題。據(jù)統(tǒng)計,2014年我國腐蝕總成本超過2.1萬億元人民幣,約占當年GDP的3.34%,其中海洋腐蝕約占總腐蝕損失的1/10以上[2]。此外,海洋油氣資源開采平臺在整個使用壽命周期內(nèi),不僅受到海水的腐蝕作用,同時夾雜著泥沙等物質(zhì)的波浪、潮汐、洋流等又會對工程裝備產(chǎn)生沖擊等作用[3],進一步加速腐蝕的發(fā)生。因此,加強海洋工程裝備的表面防護強化十分必要,也十分迫切。表面工程技術(shù)是提升工程裝備服役壽命或賦予工部件表面新功能的重要有效手段之一[4]。熱噴涂技術(shù)作為表面工程技術(shù)的重要技術(shù)手段,由于其取材廣,成本可控,可大面積制備,已廣泛應(yīng)用于海洋裝備的表面強化或防護[5]。其中,電弧噴涂技術(shù)(Arc Spraying Technique)是一種低成本、低能耗、高沉積效率的熱噴涂技術(shù),以電弧為熱源,將熔化了的金屬絲用高速氣流霧化,并沉積于工件表面形成涂層,電弧噴涂技術(shù)工程化應(yīng)用約占我國熱噴涂技術(shù)總數(shù)的20%[6]。
電弧噴涂作為海工裝備表面防腐的一種重要方法,其防腐原理為物理隔離和電化學保護。目前,表面防腐噴涂材料主要以相對活潑的金屬,如鋅(Zn)、鋁(Al)及其合金,鎳基、鐵基合金等耐蝕金屬[7]。日本JACC(Japan Association of Corrosion Control)熱噴涂委員會的Kuroda等[8-9]對Zn、A1及Zn/A1熱噴涂涂層進行了長期暴露試驗,結(jié)果表明,Al、Zn及其合金涂層在海洋環(huán)境下具有良好的耐腐蝕性能,在海洋鋼結(jié)構(gòu)表面防護領(lǐng)域占有重要地位。鋁作為重要的腐蝕防護用材料,其本身存在硬度低、摩擦系數(shù)高,不耐磨等問題,這些性能短板嚴重制約了鋁及其涂層的應(yīng)用[10-11]。目前,提高材料摩擦學性能的常用手段是添加硬質(zhì)材料,如陶瓷相顆粒(Al2O3、B4C、SiC、TiC、WC),提高復合材料的硬度,從而提高材料的耐磨性[12-13];或通過添加減磨材料,如碳基材料、MoS2,降低復合材料摩擦系數(shù),以提高其耐磨性[14]。碳基材料具有摩擦系數(shù)低的特點,如碳納米管、石墨烯、石墨、碳纖維等,在抗摩擦磨損領(lǐng)域具有良好的應(yīng)用前景[15-16]。其中,碳纖維(CFs)因具有高抗拉強度、高模量和優(yōu)異的自潤滑減磨功能而作為增強材料被廣泛應(yīng)用于聚合物樹脂、陶瓷和金屬基復合材料[17]。大量研究結(jié)果[18-19]表明,由于CFs本身具有無序的石墨結(jié)構(gòu),使CFs可在復合材料中作為減磨劑,使復合材料具有良好的減磨潤滑功能。
為了實現(xiàn)多種材料的復合性能,傳統(tǒng)電弧噴涂材料技術(shù)已無法滿足多功能性能需求。粉芯絲材技術(shù)是利用不同金屬外皮(如低碳鋼、Ni、Al、Cu、不銹鋼等帶材)包覆不同粉芯(如金屬合金、陶瓷、氧化物、碳化物粉末等),因同時具有金屬絲材和粉末的優(yōu)點,拓寬了涂層材料的成分和種類范圍,滿足了對涂層多功能化、多元化和高性能化的要求。粉芯絲材的出現(xiàn),
大大拓展了傳統(tǒng)電弧噴涂技術(shù)的應(yīng)用范圍[20-22]。近年來,粉芯絲材電弧噴涂涂層已在耐磨損、防腐蝕和耐高溫防護涂層等領(lǐng)域占據(jù)著重要地位[23]。本文研究的主要目的是使用粉芯絲材技術(shù),利用電弧噴涂技術(shù)制備碳纖維增強鋁基復合涂層。最終制備的碳纖維增強鋁基復合涂層具有優(yōu)異的耐腐蝕性能,兼具優(yōu)異的自潤滑減磨性能。通過XRD對涂層的物化性能進行檢測,通過SEM檢測其表面和斷面結(jié)構(gòu)和特征,通過電化學、中性鹽霧試驗評價其耐腐蝕性能,通過摩擦磨損試驗機對其摩擦學性能進行檢測。結(jié)果表明,所制備的碳纖維增強鋁基復合涂層具有優(yōu)異的耐蝕、自潤滑減磨性能。
試驗材料選用鋁帶(寬度為7 mm,厚度為400 μm)作為粉芯絲材外殼,選用碳纖維粉末(長度為30~ 50 μm,直徑為6 μm,日本東邦HTS40-12K型)和鋁粉(球形,粒徑為40~75 μm,長沙天久金屬材料有限公司),按質(zhì)量比3︰2進行機械混合,再用粉芯絲材成型機按填充率26%(質(zhì)量分數(shù))進行填充,最終獲得碳纖維增強鋁基粉芯絲材(2 mm)。
選用碳鋼為涂層基體材料(20 mm×30 mm× 2 mm),先用丙酮對基底材料進行超聲清洗,再用噴砂機進行表面噴砂,以實現(xiàn)基體除油、除銹。最后使用碳纖維增強鋁基粉芯絲材和實心純鋁絲材,通過電弧噴涂系統(tǒng)制備Al/CFs復合涂層和純Al涂層。其中,純Al涂層作為試驗對照組,噴涂工藝參數(shù)見表1。
1.3.1 物化性能表征
利用Bruker-AXS X–射線衍射儀表征涂層的主要物相組成,用單色CuKα為輻射源,操作電壓、電流分別為40 kV、30 mA,掃描時間為10 min,2值為10°~90°,掃描速率為0.1 (°)/s。利用FEI Quanta FEG250型掃描電子顯微鏡對涂層的微觀形貌進行表征,利用自帶的EDX對涂層進行成分表征。利用Image J軟件對獲取的涂層斷面SEM圖片進行分析,計算獲得各個涂層的孔隙率。依據(jù)GB/T 228—2002,利用萬能力學試驗機測試涂層的結(jié)合強度。其中,對偶樣用E7膠對粘,圓柱試樣的直徑為25.4 mm,測試過程中,拉伸速率為1 mm/min。使用MVS-1000D1維氏硬度計表征涂層硬度,其中載荷為100 g,保壓15 s,每組樣上取3點測量的平均值作為最后的結(jié)果。
1.3.2 耐蝕性能表征
采用傳統(tǒng)的三電極體系在M273A電化學工作站對涂層的動電位極化曲線測試來評估其耐腐蝕性能。其中,鉑片為輔助電極,飽和甘汞電極為參比電極,試樣為工作電極,涂層測試面積為15 mm×10 mm。在25 ℃下,將試樣浸泡在質(zhì)量分數(shù)為3%的NaCl溶液中。測試前,先進行開路電位檢測,確保測試前開路電位達到穩(wěn)定狀態(tài),掃描范圍為–1.5~0.5 V,掃描速率0.01 V/s[24]。采用標準中性鹽霧試驗測試涂層的耐腐蝕性能[25],其中NaCl 溶液的質(zhì)量分數(shù)為5%,溶液的pH值為6.7~7.2。試驗過程中,表面未噴涂涂層樣品作為空白對照。
表1 電弧噴涂制備碳纖維增強鋁基復合涂層工藝參數(shù)
1.3.3 摩擦學性能表征
采用布魯克的UMT-3多功能摩擦磨損試驗機測試復合涂層的摩擦學行為。摩擦試驗前,先用2 000目砂紙對各涂層進行拋光,然后采用往復滑動方式進行涂層摩擦磨損測試。相關(guān)測試參數(shù)如下:摩擦配副為3 mm的316L不銹鋼球,球固定不動,施加載荷為2 N,頻率為2 Hz,單次滑動行程5 mm,環(huán)境溫度為25 ℃,環(huán)境相對濕度為40%~60%,運行時間為60 min。采用Alpha-Step IQ臺階儀測試磨痕的截面輪廓,通過計算獲得涂層的磨損率。涂層磨損率的計算式為[26]:
式中:為磨損率,mm3/(N·m);為磨損體積,mm3,為對輪廓截面進行積分計算得到的磨痕輪廓積分面積;為單次行程;為法向載荷,N;為滑行距離,m。
利用掃描電子顯微鏡觀察到的試樣表面及其斷面微觀形貌如圖1所示。從圖1可以看到,Al基涂層表面具有典型的熱噴涂涂層表面微觀形貌,表面存在典型的扁平粒子,且受熱熔化良好,經(jīng)高速氣流加速撞擊到基體上,相互疊加形成涂層。在Al/CFs復合涂層表面可以觀察到交錯分布著的長棒狀碳纖維,大部分碳纖維被熔融的金屬扁平粒子覆蓋,涂層表面僅暴露出少量碳纖維。從其橫截面圖可以看到,Al基涂層的涂層/基體界面處無分層、裂紋或剝落現(xiàn)象,顯示出良好的結(jié)合狀態(tài)。由于鋁的熔點較低,涂層中沒有形成典型的層狀組織,意味著鋁基粉芯絲材在噴涂過程中熔化良好。此外,在Al/CFs復合涂層斷面可以觀察到碳纖維(黑色部分嵌在金屬基體中)分布在涂層中(見圖b1),且在Al/CFs界面處無明顯分層等缺陷(見圖b2)。但是,也可以觀察到復合涂層中碳纖維的含量與原Al/CFs粉的含量并不成正比。采用ImageJ軟件分析計算復合涂層的斷面形貌,結(jié)果表明,復合涂層中CFs的體積分數(shù)約3.5%,遠低于原始復合粉末中的CFs含量。這主要是由于噴涂過程中粒子的飛行速度快,熔化時間短,絕大部分碳纖維無法瞬間被熔化的鋁滴包覆,且其密度較小,又會在高速氣流作用下被直接吹走,導致這些碳纖維粉末不能實現(xiàn)有效沉積。此外,利用萬能力學試驗機進一步檢測涂層結(jié)合力,結(jié)果表明,純Al涂層的結(jié)合力為(23.11±4.66) MPa,Al/CFs涂層的結(jié)合力為(22.43± 2.14) MPa,2種涂層均具有良好的結(jié)合力。利用Image J軟件對獲取的涂層斷面SEM圖片進行分析,并計算涂層孔隙率,結(jié)果表明,Al/CFs復合涂層和純Al涂層的平均孔隙率分別為0.48%和0.63%,復合涂層與鋁涂層的孔隙率無顯著差異,均具有良好的致密度,有利于提高其耐腐蝕性能。
圖1 Al基涂層表面及其斷面SEM形貌
Al基涂層樣品的XRD圖譜見圖2。從XRD圖譜可以看到,制備的Al/CFs復合涂層主要由Al的特征峰組成[24],未能檢測到明顯的CFs特征峰。致使這一結(jié)果的主要原因是,一方面由于涂層中有效沉積的CFs含量過少,XRD儀器未能有效檢測;另一方面,可能是由于噴涂過程中熔融的鋁液滴對碳纖維形成了一定程度的金屬包覆(圖1b1中可以明顯觀察到碳纖維表面有熔化的金屬液覆蓋),使得碳纖維組分未能被有效檢測。同時,Al基涂層均未檢測到金屬Al的氧化物特征峰,表明在整個涂層沉積過程中,涂層氧化作用微乎其微,這對于形成低氣孔率、高致密度涂層是十分有利的[27]。這與涂層斷面的SEM結(jié)果一致,未在涂層內(nèi)部觀察到明顯的氧化物夾雜缺陷。熱噴涂涂層沉積過程是由大量撞擊到基體后變形鋪展的扁平粒子堆積而成,其中飛行粒子的氧化機制是整個涂層氧化的主導機制。當夾雜著氧化物的粒子在基體上鋪展(氧化層在熔化粒子下面)、凝固時,會形成涂層間的氧化物夾雜;當氧化物存在于粒子內(nèi)部時,則會形成涂層內(nèi)部的氧化物夾雜。涂層的氧化程度顯著影響著涂層的性能,如氣孔率增加、致密度下降,而低氣孔率、低氧化物含量、高致密度對涂層性能,尤其是抗腐蝕性能極其重要[28-29]。
圖2 不同樣品的XRD曲線
試樣在載荷2 N下的平均摩擦系數(shù)如圖3a所示,2種涂層在測試過程中均未發(fā)生涂層失效現(xiàn)象。從摩擦系數(shù)曲線可以看出,在Al基復合體系中,添加CFs成分,可顯著減小涂層的摩擦系數(shù),Al/CFs復合涂層在干式摩擦磨損條件下具有較好的自潤滑性能。對于碳纖維、二硫化鉬等固體自潤滑材料構(gòu)成的復合材料而言,其摩擦系數(shù)值的降低是正常的[30-31]。隨著涂層磨損的進行,涂層中的碳纖維逐漸暴露來,并隨著摩擦磨損的進行,在涂層表面形成了具有良好自潤滑減磨能力的致密碳質(zhì)層[32],最終避免了涂層與對磨副鋼球的直接摩擦接觸。Al/CFs復合涂層顯著降低了Al基涂層的磨損率(見圖3b),Al/CFs復合涂層的磨損率(8.46×10–4mm3·N–1·m–1)僅為純Al涂層的1/2,Al/CFs復合涂層具備更低的摩擦系數(shù),其自潤滑減磨特性使得涂層具有更佳的耐磨損性能。
圖3 Al基涂層的摩擦系數(shù)曲線及其磨損率測試結(jié)果
利用掃描電子顯微鏡觀察涂層磨痕和磨球的表面形貌,進一步對鋁基涂層的磨損機制進行分析。從圖4可以看到,純Al涂層(見圖4a)與Al/CFs復合涂層(見圖4c)的磨損形貌是完全不同的。Al/CFs復合涂層的磨損軌跡相對連續(xù)、光滑,溝槽較小,其對磨球表面可以觀察到明顯的犁溝現(xiàn)象(見圖4d),粘附的金屬鋁很少,粘著磨損的典型特征不明顯。進一步觀察Al/CFs復合涂層摩擦磨損過程中的磨痕局部放大圖(見圖5),可以看到,磨痕內(nèi)部有清晰的裂紋和較大的磨屑剝落(見圖5a),這是疲勞磨損的典型現(xiàn)象[33]。隨著摩擦磨損過程的進行,復合涂層中的CFs逐漸從涂層中暴露于涂層表面(見圖5b),犁溝現(xiàn)象逐漸加?。ㄒ妶D5c),最終使碳纖維從涂層中被拔出,形成韌窩(見圖5d)。綜合分析后得出,Al/CFs復合涂層的主要磨損機制是磨粒磨損(主導機制)和疲勞磨損。純Al涂層的磨痕上則可觀察到許多微裂紋和深犁溝,在磨球表面則可以看到大量的磨削材料(見圖4b)。一般而言,摩擦磨損試驗后,材料表面的磨痕犁槽越深,涂層的磨損率值越高[34]。在純Al涂層磨痕上觀察到深犁溝、大量切屑,這是粘著磨損機制的典型特征[35]。這主要是由于熱噴涂涂層本身是由飛濺的扁平粒子堆積而成,扁平粒子間主要依靠物理機械鉚釘作用相互結(jié)合,隨著往復滑動的進行,其對涂層造成交替應(yīng)力,削弱了扁平粒子飛濺區(qū)界面的結(jié)合力[36],最終導致涂層剝離、剝落。同時,這些剝離或剝落的粒子又作為“第三相”,使涂層在摩擦磨損過程中的摩擦系數(shù)發(fā)生波動,進一步加速涂層的磨損[37]。
圖4 摩擦磨損試驗后Al基涂層及其對磨副(316L不銹鋼球)表面的SEM形貌
圖5 Al/CFs復合涂層摩擦磨損過程高倍SEM形貌
金屬鋁及其復合防護涂層最廣泛的應(yīng)用場景,即利用其耐腐蝕特性為鋼結(jié)構(gòu)等海洋工程裝備提供腐蝕防護。因此,對Al基涂層的耐蝕性評價是十分有必要的。本研究中,主要通過動電位極化曲線和中性鹽霧試驗(NSS)測試來綜合評估涂層的耐蝕性。利用Tafel直線外推法計算試樣的corr和corr。純Al涂層、Al/CFs復合涂層和空白試驗組Q235碳鋼基體的電化學極化曲線和詳細參數(shù)對比見圖6和表2。由圖6和表2可以直觀地看出,純Al涂層和Al/CFs復合涂層的腐蝕電位未有顯著變化,corr分別為–1 048、–1 064 mV,相比于純Al涂層樣品,Al/CFs復合涂層樣品的腐蝕電位稍有下降。同樣的,Al/CFs復合涂層的腐蝕電流密度相較于純Al涂層也有略微升高。在加入碳纖維后,Al基涂層的耐腐蝕性能稍有減弱,但影響不明顯,Al/CFs涂層仍具有良好的耐腐蝕性。進一步從動電位極化曲線來看,Q235碳鋼的corr(–830.4 mV)比鋁基涂層更高,corr(1.118× 10–6A/cm2)則明顯低于鋁基涂層。一般情況下,腐蝕電位相對越高,發(fā)生腐蝕的傾向越小,腐蝕電流密度越大,腐蝕速率越快[38]。因此,理論上Q235碳鋼的腐蝕傾向應(yīng)該越小,而實際情況卻并非如此。這主要是由于金屬Al相比于鐵更活潑,基體和鋁基涂層等不同金屬之間接觸產(chǎn)生的電偶效應(yīng)的發(fā)展也會引起電偶腐蝕,從而引發(fā)電偶電池的形成,加速鋁基涂層的腐蝕[39],Al基涂層主要作為犧牲陽極的作用保護鋼基體[40]。Al元素與氧的親和力大,Al金屬表面發(fā)生腐蝕后,會在其表面會生成一層穩(wěn)定的氧化膜,氧化膜能起到屏障、阻隔作用,避免了腐蝕介質(zhì)進入涂層內(nèi)部,從而阻止腐蝕的深入發(fā)展[41]。
為了進一步表征Al基涂層的耐腐蝕性能,對Al基涂層進行了電化學阻抗模值和相角分析。圖7為Al基涂層的電化學阻抗模值和相角譜圖。從圖7可以看到,純Al涂層有較高的阻抗模值和相角,其耐蝕性稍好于Al/CFs復合涂層,但2種涂層的差別不顯著。隨著電化學試驗時間的延長,涂層發(fā)生腐蝕反應(yīng),但由于表面生成了致密的氧化膜,阻隔電解液進入涂層內(nèi)部,使涂層進一步發(fā)生腐蝕反應(yīng)的阻力增加,腐蝕速度放緩。
圖6 不同試樣的動電位極化曲線
表2 各組試樣在3.5% Nacl溶液中的電化學參數(shù)
圖7 不同試樣的電化學Bode圖
利用中性鹽霧試驗進一步研究涂層的宏觀耐腐蝕性能。圖8 a1—c1為中性鹽霧試驗720 h后樣品的數(shù)碼照片,結(jié)果表明,鋁基涂層表現(xiàn)出良好的耐腐蝕性能,Al基涂層表面均未觀察到可見的白色腐蝕產(chǎn)物,而Q235鋼基體則出現(xiàn)了大量的腐蝕產(chǎn)物,表明其腐蝕嚴重。中性鹽霧試驗720 h后樣品的斷面SEM形貌如圖8a2—c2所示。結(jié)果表明,相較于Q235鋼基體,Al基涂層的腐蝕層厚度明顯減小,且涂層內(nèi)部未發(fā)生明顯腐蝕,說明腐蝕現(xiàn)象僅發(fā)生于涂層表面。腐蝕介質(zhì)通過涂層孔隙和扁平粒子邊界進入涂層內(nèi)部,導致涂層內(nèi)部的活性區(qū)發(fā)生腐蝕[42]。對于鋁基涂層而言,涂層內(nèi)部的微孔會因腐蝕產(chǎn)物的局部堆積而被堵塞,從而提高了涂層的抗腐蝕性能,稱為“堵塞效應(yīng)”[41]。腐蝕產(chǎn)物中Al3+的存在提高了腐蝕產(chǎn)物的穩(wěn)定性,穩(wěn)定存在的腐蝕產(chǎn)物有利于實現(xiàn)涂層的屏障作用(或腐蝕防護能力),從而有效阻止腐蝕介質(zhì)的進一步侵入。在含氯離子的溶液中,鋁的腐蝕產(chǎn)物能夠抑制金屬溶解的陽極反應(yīng)[43]。這些穩(wěn)定的腐蝕產(chǎn)物可作為涂層的密封劑,阻止涂層進一步腐蝕。中性鹽霧試驗結(jié)果表明,碳纖維的加入對鋁基涂層的耐蝕性沒有顯著影響。
圖8 不同試樣組中性鹽霧試驗720 h后的數(shù)碼照片及其斷面SEM形貌
1)利用粉芯絲材技術(shù)即在鋁基粉芯中復合碳纖維可以有效實現(xiàn)碳纖維增強鋁基粉芯絲材的制備,并利用電弧噴涂技術(shù)成功制備了Al/CFs復合涂層。碳纖維在復合涂層中分布良好,它可作為固體潤滑劑在涂層的摩擦學功能性應(yīng)用中發(fā)揮著重要作用。與純鋁涂層相比,Al/CFs復合涂層具有較低的摩擦系數(shù)和低的磨損率。Al/CFs復合涂層和純鋁涂層的主要磨損機制由于碳纖維的加入而完全不同,主導磨損機制分別為磨粒磨損和粘著磨損。
2)利用電化學試驗、中性鹽霧試驗系統(tǒng)評價了鋁基涂層的耐腐蝕性能,在鋁基涂層體系中添加少量碳纖維,并不顯著影響整體涂層的耐腐蝕性能。相比于純鋁涂層,720 h中性鹽霧試驗后,Al/CFs復合涂層表面也未觀察到明顯的腐蝕產(chǎn)物出現(xiàn),涂層整體的耐腐蝕性能良好。
3)電弧噴涂技術(shù)是一種低成本、大面積、高效制備防護涂層的技術(shù),利用該技術(shù)制備的高性價比Al/CFs復合涂層在具有良好耐腐蝕性能的前提下,賦予原有鋁基涂層體系更好的耐磨、減磨性能,拓展了鋁基涂層在海洋工程裝備中作為屏蔽和犧牲保護層的常規(guī)應(yīng)用,在海洋工程裝備面臨的復雜腐蝕、摩擦磨損相耦合的應(yīng)用場景具有重要潛在的價值。
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Carbon Fiber Reinforced Aluminum-based Anti-attrition Composite Coating Prepared by Arc Spraying
1,2,3,1,1,3,1,3,1,3,1,3,1,3
(1. Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Zhejiang Ningbo 315201, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China; 3. Cixi Institute of BioMedical Engineering, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Zhejiang Cixi 315300, China)
With the development of the ocean economy in recent decades, such as oil and gas exploitation in deep ocean environment, marine equipment urgently needs advanced protective technologies against the special service environment like high speed, strong friction, lubrication, etc. How to further improve the properties of marine equipment such as corrosion resistance and abrasion resistance becomes the key problem. Thermal spraying has been proven to be an efficient surface protection technology, in particular in fabricating anti-corrosion coatings on marine equipment surfaces. Among the marine protective coatings developed in past decades, thermal sprayed aluminum coating is evidenced to be one of the most economical and efficient corrosion protection coating. However, compared with its excellent corrosion resistance in marine environment, the tribological properties of aluminum are poor, such as high friction coefficient and low lubrication, which limits its application. In order to improve the tribological properties of the aluminum coating, adding low friction materials like carbon based materials is a feasible way.
The work aims to prepare carbon fiber reinforced aluminum-based anti-attrition composite coating. The carbon fiber reinforced aluminum-based (Al/CFs) composite powder core wire was fabricated, and the Al/CFs composite coating was prepared by arc spraying. The properties of the composite coating were characterized. The micromorphology and the physicochemical properties of the coating were examined by SEM and XRD. The tribological properties and corrosion resistance of the coating were tested by friction and wear testing machine, electrochemical workstation and neutral salt spray test chamber. The effect of carbon fibers on the properties of the Al-based coating was comprehensively evaluated. The results showed that the tribological properties of the Al-based composite coating with carbon fibers were significantly improved compared with the pure Al coating, with the friction coefficient decreasing from ~0.4 to ~0.2 and the wear rate decreasing from ~2.0×10–3mm3/(N·m) to ~8×10–4mm3/(N·m). Scanning electron microscopy (SEM) was used to examine the surface wear morphologies of the composite coating and its wear pairs, and the wear mechanism of the coating was also analyzed. It was found that the wear mechanism of the Al/CFs composite coating was mainly abrasive wear, while that of the pure Al coating was adhesive wear. The corrosion trend of the coating was tested by the electrodynamic polarization curve and the Bode curve. The electrochemical results showed that the addition of carbon fibers did not significantly affect the corrosion resistance of the Al-based coating. Further, neutral salt spray test also showed that all the Al-based coatings had excellent corrosion resistance with no obvious corrosion products found on the coating surface after 720 h NSS test. In summary, the Al/CFs composite powder core wire and its coating can be prepared by powder core wire technology and arc spraying. Addition of carbon fibers into the aluminum coating system can significantly reduce the friction coefficient and wear rate of the composite coating without affecting the corrosion resistance of the original aluminum coating. The composite coating reveals excellent anti-corrosion and anti-attrition performances and can expand the application of Al-based coating in the field of corrosion resistance and wear reduction.
powder core wire; carbon fiber reinforced; anti-attrition; corrosion resistance;arc spraying; composite coating
TG174.4
A
1001-3660(2023)01-0072-10
10.16490/j.cnki.issn.1001-3660.2023.01.008
2021–12–01;
2022–04–06
2021-12-01;
2022-04-06
國家自然科學基金(51802322);寧波市科技創(chuàng)新2025重大專項(2018B10054);寧波國際科技合作項目(2017D10011)
The National Natural Science Foundation of China (51802322); The S & T Innovation 2025 Major Special Programme of Ningbo (2018B10054); The International Scientific and Technological Cooperation Project of Ningbo (2017D10011)
王應(yīng)泉(1978—),男,碩士研究生,主要研究方向為表面涂層技術(shù)。
WANG Ying-quan (1978-), Male, Postgraduate, Research focus: surface coating technology.
黃晶(1985—),男,碩士,高級工程師,主要研究方向為熱噴涂技術(shù)及涂層。
HUANG Jing (1985-), Male, Master, Senior engineer, Research focus: thermal spraying technology and coating.
王應(yīng)泉, 房立家, 淡焱鑫, 等. 電弧噴涂碳纖維增強鋁基耐蝕減磨復合涂層研究[J]. 表面技術(shù), 2023, 52(1): 72-81.
WANG Ying-quan, FANG Li-jia, Dan Yan-xin, et al. Carbon Fiber Reinforced Aluminum-based Anti-attrition Composite Coating Prepared by Arc Spraying[J]. Surface Technology, 2023, 52(1): 72-81.
責任編輯:劉世忠