本文選題：微弧氧化 + 7E04鋁合金　； 參考：《西南石油大學》2017年碩士論文

【摘要】：目前鋁合金鉆桿在石油鉆探領域得到了廣泛的應用。面對鋁合金鉆桿在使用過程中表面性能不足的問題,本課題提出通過微弧氧化表面處理技術來解決。本文以鉆桿用7E04鋁合金為基體材料,在硅酸鹽電解液體系下采用單因素變量法系統(tǒng)地研究了Na2SiO3添加量、氧化電流密度、占空比及氧化時間這四個主要工藝參數(shù)對7E04鋁合金微弧氧化膜基本性能的影響,確定了最佳基本工藝參數(shù)范圍;在工藝優(yōu)化條件下,借助SEM、EDS和XRD等分析測試方法研究了 Na_2WO_4濃度對7E04鋁合金微弧氧化膜的性能的影響;探討了 Na_2WO_4在微弧氧化過程中的改性機理。研究微弧氧化基本工藝發(fā)現(xiàn),在溫度20℃、頻率100Hz條件下,鉆桿用7E04鋁合金微弧氧化的最佳工藝參數(shù)范圍為:Na2SiO3 15.0g/L,電流密度4A/dm2～8A/dm2,占空比20%～60%,氧化時間30min。此時獲得的微弧氧化膜厚度、顯微硬度及耐蝕性可得到優(yōu)化。Na2W04改性階段確定氧化電流密度為6A/dm2,占空比為40%,分別添加Na_2WO_4濃度為2.0g/L、4.0g/L、6.0g/L、8.0g/L、10.0g/L制備五組改性微弧氧化膜。研究發(fā)現(xiàn)微弧氧化膜表面顏色隨Na_2WO_4濃度的增加而逐漸加深,從灰白色逐漸轉變?yōu)榛液谏?微弧氧化過程中氧化電壓稍有下降,膜層厚度也逐漸下降;膜層中W元素含量也呈上升趨勢,其在膜層中的主要存在形式為WO3,且具有高熔點、高硬度,同時膜層表面逐漸趨于平整、致密,使得微弧氧化膜的顯微硬度和耐蝕性大幅提高。在Na_2WO_4參與微弧氧化反應過程中,等離子體放電產生的高溫、高壓使得WO42-逐漸向WO3轉化與基體氧化物混合成膜,分散在膜層中,使膜層結構發(fā)生改變。由于WO3具有高熔點,導致在放電擊穿中,可熔融的膜層薄弱部位減少,導致放電劇烈程度下降,放電火花更加細小、均勻,有效地抑制了膜層表面大尺寸放電孔的產生。
[Abstract]:At present, aluminum alloy drill pipe has been widely used in the field of oil drilling. Facing the problem of insufficient surface performance of aluminum alloy drill pipe in use, this paper proposes to solve the problem by micro-arc oxidation surface treatment technology. In this paper, 7E04 aluminum alloy used for drilling pipe was used as the base material, and the addition amount of Na2SiO3 and oxidation current density were systematically studied by single factor variable method in silicate electrolyte system. The effects of duty cycle ratio and oxidation time on the basic properties of 7E04 aluminum alloy micro-arc oxide film were studied. The effect of Na_2WO_4 concentration on the properties of 7E04 aluminum alloy micro-arc oxide film was studied by means of SEMDAs and XRD, and the modification mechanism of Na_2WO_4 in the process of micro-arc oxidation was discussed. The basic process of micro-arc oxidation is studied. It is found that under the condition of temperature 20 鈩，

本文編號：1851122