(1. 江蘇科技大學(xué) 材料科學(xué)與工程學(xué)院，鎮(zhèn)江 212003；
2. 江蘇科技大學(xué) 機械工程學(xué)院，鎮(zhèn)江 212003)
摘 要: 以Ni-Al為粘結(jié)層，在AZ91D鎂合金基體上等離子噴涂Ni-Al/Al2O3、Ni-Al/Al2O3-13%TiO2 (Ni-Al/AT13)、Ni-Al/Al2O3-20%TiO2(Ni-Al/AT20)復(fù)合涂層及Ni-Al/Al2O3/Al2O3-13%TiO2/Al2O3-20%TiO2 (Ni-Al/Al2O3/AT13/AT20) 梯度涂層，利用SEM、EDS和XRD分析涂層的微觀組織特征，通過硬度、拉伸和熱震實驗研究涂層硬度、結(jié)合強度和抗熱震性能，并與直接噴涂Al2O3、AT20的涂層進行比較。結(jié)果表明：Ni-Al粘結(jié)層因“自粘結(jié)”效應(yīng)與基體形成較為致密并具有冶金結(jié)合的界面，且與Al2O3、AT13和AT20陶瓷層互有滲透、交叉和嚙合，涂層致密性及結(jié)合力大為提高，表現(xiàn)出優(yōu)良的抗熱震性能。Al2O3涂層主要由亞穩(wěn)態(tài)γ-Al2O3組成，AT20涂層以Al2O3和Al2TiO5為主。鎂合金表面噴涂Al2O3陶瓷層后硬度大幅提高，由于加入TiO2，AT13和AT20涂層的硬度略低于Al2O3涂層的。Ni-Al/Al2O3-TiO2復(fù)合陶瓷的涂層結(jié)合強度高于Ni-Al/Al2O3單一陶瓷涂層的，而Ni-Al/ Al2O3/AT13/AT20梯度涂層的結(jié)合強度比Ni-Al/AT20涂層的更高。
關(guān)鍵字: 鎂合金；等離子噴涂；Ni-Al粘結(jié)層；陶瓷涂層；結(jié)合強度
plasma-sprayed on AZ91D magnesium alloy
（1. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China）
Abstract:By means of plasma spraying, Ni-Al/Al2O3, Ni-Al/Al2O3-13%TiO2 (Ni-Al/AT13) and Ni-Al/Al2O3-20%TiO2 (Ni-Al/AT20) composite coatings as well as Ni-Al/Al2O3/Al2O3-13%TiO2/Al2O3-20% TiO2 (Ni-Al/Al2O3/AT13/AT20) gradient coating were fabricated on the AZ91D magnesium alloy with Ni-Al as the base coating. The microstructure characteristics of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD). The hardness, bonding strength and thermal shock properties of the coatings were evaluated by microhardness, tensile and thermal shock tests. The coatings with Ni-Al as the base coating were compared with Al2O3 and AT20 coatings without Ni-Al. The results show that denser interface with metallurgical bonding forms between Ni-Al and AZ91D substrate due to Ni-Al base coating’s self adhesive effect. Ni-Al coating can interpenetrate into, cross and gear with Al2O3, AT13 and AT20 coatings, thus remarkably improving the compactness, bonding strength and resistance to thermal shock. Al2O3 coating is mainly composed of metastable γ-Al2O3 while AT20 coating mainly consists of Al2O3 and Al2TiO5. After plasma sprayed with Al2O3 coating, the surface hardness of AZ91D alloy increases evidently. The hardness of AT13 as well as AT20 coatings is slightly lower than that of Al2O3 coating because of the addition of TiO2. The bonding strength of Ni-Al/Al2O3-TiO2 composite ceramic coating is higher than that of Ni-Al/Al2O3 single ceramic coating and Ni-Al/Al2O3/AT13/AT20 gradient coating shows high bonding strength than Ni-Al/AT20 coating.
Key words: magnesium alloy; plasma-spraying; Ni-Al coating; ceramic coating; bonding strength
