摘要
在K38G高温合金基体上分别设计涂覆了75%搪瓷釉+25%Al2O3(E25A)和70%搪瓷釉+20%Al2O3+10%NiCrAlY (E20A10M) 2种搪瓷基复合涂层,对比研究了2种搪瓷基复合涂层在900℃下模拟燃气热冲击条件下的防护机制。热冲击的火焰采用C3H8+O2混合气体产生,喷射到试样涂层表面的压力为0.4 MPa,火焰喷射到试样涂层达到900℃后保持15 s,而后空气中冷却120 s为一个热冲击循环周期。结果表明,经燃气冲击150 cyc后,2种涂层与合金基体界面结合牢固,表现出优异的抗界面剥落能力。其中,E25A涂层热冲击前后的涂层组织结构无明显变化,表面完好,Al2O3第二相的加入提高了搪瓷的高温稳定性;而E20A10M涂层热冲击后表面产生了孔洞、开裂,发生了轻微的表层剥离。金属粉与搪瓷的界面反应Cr(NiCrAlY)+ZnO(enamel)→CrO(interface)+Zn↑,致使涂层表面鼓包,在燃气切应力和界面热应力作用下,表层金属颗粒以及搪瓷发生剥离。
High-temperature-resistant enamel coatings have been reported to be applied in non-critical hot end components of aero-engine and gas turbine recently.Although the enamel with a series of excellent properties can be as high-temperature-resistant coating material under appropriate condition, its lower soft point and inherent brittleness limit their use in broader application under severe service con- dition.Enamel-based composite coatings (an enamel matrix with the addition of ceramic particles and/or metal platelets)can remarkably increase the properties of the enamel coating and their protection mechanism under dynamic thermal shock needs further investigation.In this work,two kinds of enamel-based composite coatings,70% enamel+25%Al2O3 and 70% enamel+20%Al2O3+10%NiCrAIY (mass fraction,%) abbreviated to E25A and E20A10M respectively,were designed and fired on K38G superalloy substrate, and their protection mechanism was comparatively studied at 900℃ under the simulated combusting gas shock.The thermal shock fire was produced by the mixture gas of C3H8+O2and its ejecting pressure on the coating surface was 0.4MPa.After the temperature has been stable at 900℃,samples were hold for 15s and then cooling down in air for 120s,constituting a thermal shock cycle.Results indicated that, after 150 cyc of thermal shock,both the coatings bond well with the alloy substrate,thus shows high resistance to spallation along interface.For the E25A coating,its microstructure had no obvious change after thermal shock and the surface is still intact.The addition of secondary phase Al2O3 increases the stability of enamel at high temperature.With regard to the E20A10M coating,holes and cracks form consecutively, and peeling'off occurs at surface after thermal shock.Interfacial reaction between the NiCrAIY particles and enamel following Cr(NiCrAlY)+ZnO(cnamel)→CrO(interfce)+Zn↑ results in the formation of enamel swelling,whichthen,under the synergistic effect of combusting gas shear stress and interface thermal stress, leads to the peeling off of enamel and metal inclusions at surface.
作者
郭策安
陈明辉
廖依敏
苏北
谢冬柏
朱圣龙
王福会
GUO Cean;CHEN Minghui;LIAO Yimin;SU Bei;XIE Dongbai;ZHU Shenglong;WANG Fuhui(Equipment Engineering School,Shenyang Ligong University,Shenyang 110159,China;Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;Chongqing Jianshe Industry (Group)LLC,Chongqing400054,China;School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China;Xinjiang Police College,Urumqi 830011,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第12期1825-1832,共8页
Acta Metallurgica Sinica
基金
国家自然科学基金项目No.51471177
中央高校基本科研业务费专项基金项目No.N160205001
辽宁省自然科学基金项目No.201602643~~
作者简介
郭策安,男,1979年生,博士;通讯作者:陈明辉,mhchen@mail.ileu.edu.cn,主要从事高温防护涂层的研究.
