Two type powders of CoNiCrAlY alloy were prepared by gas atomization(GA)and water atomization(WA)respectively,then which were used as feedstock powders to further prepared the corre-sponding coatings on a directionally solidified high temperature alloy DZ411by using high velocity oxygen fuel(HVOF)technique and subsequently they were subjected to proper subsequent vacuum heat treat-ment.The flowability and apparent density of the prepared powders were measured according to GB/T 1484 and GB/T 1479.Meanwhile,the phase composition,microstructure,microhardness,and adhesive strength to the substrate of the prepared coatings were characterized via optical microscopy and scan-ning electron microscopy,automatic hardness tester,and universal testing machine.The high tempera-ture oxidation performance of the coatings/DZ411 was assessed in air at 1050℃ for 200 h.The results show that compared with WA,the CoNiCrAlY powder prepared by GA is spherical or nearly spherical,with good flowability and high apparent density.The prepared GA coating has a dense and uniform struc-ture with high β phase content,low porosity,high adhesive strength and high microhardness.After vacu-um heat treatment,mutual fusion of particles was clearly observed within the two coatings,while the amount of βphase increases and its distribution becomes much more uniform,correspondingly,their po-rosity and microhardness decrease.The adhesive strength of WA coating after vacuum heat treatment has been improved,but there are still larger pores within the coating.The vacuum heat treated GA coat-ing presents much better oxidation resistance.
关键词
材料表面与界面/GA/WA/CoNiCrAlY粉末/HVOF涂层/真空热处理/组织结构/性能
Key words
surface and interface in the materials/gas atomization/water atomization/CoNiCrAlY powder/HVOF coating/vacuum heat treatment/microstructure/properties
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