Co-Pt改性铝化物涂层的氧化行为

[目的]铝化物涂层的抗氧化性能及高温服役性能亟待提高。[方法]采用电镀和高温气相渗铝的方法,在镍基单晶高温合金表面制备了Co改性铝化物(NiCoAl)涂层、Pt改性铝化物(NiPtAl)涂层和Co/Pt共改性铝化物(NiCoPtAl)涂层,利用扫描电镜(SEM)、能谱仪(EDS)及X射线衍射仪(XRD)研究了3种涂层在1 100℃下恒温氧化过程中的氧化行为及组织结构演变,探究Co的添加对铝化物涂层抗氧化性能及涂层/基体界面组织结构演变的影响。[结果]恒温氧化300 h后,NiCoAl涂层表现出最差的抗氧化性能,NiCoPtAl涂层和NiPtAl涂层的抗氧化性能则更优,它们的单位面积质量依次增大了0.426 26、0.342 53和0.296 01 mg/cm^(2)。NiCoPtAl涂层试样互扩散区和二次反应区中的析出相较其他两种涂层少。[结论]适量Co的添加对铝化物涂层表面氧化层的形成有促进作用。在Co和Pt的协同作用下,铝化物涂层/单晶界面组织的稳定性更好。

Microstructure and hot corrosion behavior of Al-Ce-Y coatings on DZ125 nickel-based alloy prepared by pack cementation process

In order to improve the hot corrosion resistance of DZ125 alloy,Ce-Y modified aluminum coatings were prepared on DZ125 alloy by pack cementation process at 950°C for 2 h.The microstructure,phase constitution and formation mechanism of the coatings were investigated.The hot corrosion behaviors of DZ125 alloy and the coatings in molten salt environment of 25%K2SO4+75%Na2SO4(mass fraction)at 900°C were studied.Results show that the obtained Al-Ce-Y coatings were mainly composed of Al3Ni2,Al3Ni and Cr7Ni3,with a thickness of about 120μm.After hot corrosion test,DZ125 alloy suffered catastrophic hot corrosion and serious internal oxidation and internal sulfidation arose.Two layers of corrosion products formed on surfaces of DZ125 alloy,including the outer layer consisting of Cr2O3 and NiCr2O4,and the inner layer of Al2O3,Ni3S2 and Ni-base solid solution.After being coated with Al-Ce-Y coating,the hot corrosion resistance of DZ125 alloy is improved notably,due to the formation of a dense scale mainly consisting of Al-rich Al2O3 in the coating layer.

DZ125合金表面Al-Ce-Y渗层的组织与摩擦磨损性能

采用扩散共渗法在DZ125合金表面制备了Ce-Y改性渗Al涂层,分析了涂层的组织结构和形成机制,对比研究了DZ125合金基体及涂层在20、300和600℃时的摩擦磨损行为。结果表明,经950℃保温2h所制备的Ce-Y改性渗Al涂层厚约125μm,组织致密,主要由Al_3Ni_2、Al_3Ni和Cr_7Ni_3相组成。Ce-Y改性渗Al涂层在20和600℃时的耐磨性能优于DZ125合金,但在300℃时其耐磨性能低于基体合金。在20℃磨损时,DZ125合金的磨损机理为剥层磨损和轻微的磨粒磨损,Ce-Y改性渗Al涂层为表面擦伤;30 0℃时DZ125合金表现为粘着磨损、剥层磨损和磨粒磨损,Ce-Y改性渗Al涂层为剥层磨损及磨粒磨损;当温度为600℃时,二者均为剥层磨损和磨粒磨损。