【摘要】：擴(kuò)大鈦合金的工程應(yīng)用范圍很大程度上取決于其表面硬度的提高及耐磨性的改善,針對此國內(nèi)外學(xué)者對鈦合金表面耐磨涂層的制備進(jìn)行了大量研究,但對于采用等離子噴焊技術(shù)制備耐磨層并對耐磨層進(jìn)行熱處理的研究較少,缺少相關(guān)研究數(shù)據(jù)。本課題采用等離子噴焊技術(shù)在8mm厚的TC4鈦板表面制備鎳基噴焊層,對鎳基噴焊層分別進(jìn)行200℃×1h、400℃×1h、600℃×1h出爐空冷的回火處理,對比分析了焊態(tài)及回火試樣的組織物相、顯微硬度及磨損性能的變化,結(jié)果表明:噴焊層由基體+過渡層+強(qiáng)化層構(gòu)成,呈典型的韌基體+硬質(zhì)相組織,基體與噴焊層界面處呈冶金結(jié)合。噴焊層基體相為固溶了Cr、B等合金元素的γ-Ni,基體中TiC、Cr7C3、CrB、TiB2等硬質(zhì)相碳化物及硼化物的彌散分布使得噴焊層顯微硬度明顯提高達(dá)到986.5HV0.5,約為TC4基材的3.5倍;兩種磨損試驗均表明噴焊層耐磨性能較TC4基材顯著提高,磨損表面無明顯粘著痕跡,僅呈輕微的磨粒磨損特征。回火處理有利于提高合金元素擴(kuò)散能力,表現(xiàn)為隨回火溫度的提高過渡層厚度不斷增加,當(dāng)回火溫度為600℃時過渡層厚度達(dá)200μm約為焊態(tài)的2倍;同時回火處理改善了過渡層組織均勻性與致密性,擴(kuò)大了基體相變區(qū)尺寸使得針狀組織分布方向由原來的和熱流方向一致逐漸變?yōu)榕c熱流方向呈45°角,從而降低界面處殘余應(yīng)力,提高噴焊層與基體的結(jié)合能力。在200℃×1h、400℃×1h回火時,碳化物及硼化物的彌散析出占主導(dǎo)地位,碳化物沿縱截面生長方向有擇優(yōu)取向,噴焊表層硬度較焊態(tài)有所提高;600℃×1h回火時,基體的粗化以及硬質(zhì)相的聚集長大占主導(dǎo),碳化物生長方向性被打亂,表層硬度略有降低。磨損試驗表明:在往復(fù)摩擦磨損試驗中,試樣耐磨性均有所提高,400℃×1h回火處理后噴焊層耐磨性能最佳,其摩擦系數(shù)最低約為0.5146比焊態(tài)降低了約0.05;其磨損量為0.0078mm3,僅為焊態(tài)的1/2;在橡膠輪磨粒磨損試驗中,200℃×1 h、400℃×1h回火試樣磨損失重較焊態(tài)分別降低了0.0039g、0.0051g,耐磨性能較焊態(tài)稍有提高;600℃×1 h處理后硬質(zhì)相的粗化及基體支撐作用的減弱反而導(dǎo)致其耐磨性降低,其磨損失重較焊態(tài)增加0.0036g。
[Abstract]:To expand the scope of engineering application of titanium alloys depends to a great extent on the improvement of their surface hardness and wear resistance. A lot of researches have been carried out on the preparation of wear-resistant coatings on titanium alloys by scholars at home and abroad. However, there is little research on the preparation of wear-resistant layer and heat treatment of wear-resistant layer by plasma spray welding, and there is a lack of relevant research data. In this paper, the plasma spray welding technology was used to prepare nickel-based spray welding layer on the surface of 8mm thick TC4 titanium plate. The nickel-based spray welding coating was treated with 200 鈩，

本文編號：2380526