γ-TiAl基合金用Al_(2)O_(3)-SiC-AlPO_(4)复合涂层抗高温氧化性能研究  

Resistance to High Temperature Oxidation of Al_(2)O_(3)-SiC-AlPO_(4) Coatings onγ-TiAl Based Alloys

作　　者：杨天南 牛合全 孔令艳[3] YANG Tiannan;NIU Hequan;KONG Lingyan(Military Representative Office of Shenyang Bureau of Navy Equipment Department,Shenyang 110043,China;Taiyuan University of Science and Technology,Taiyuan 030024,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]海装沈阳局驻沈阳地区某军事代表室,沈阳110043 [2]太原科技大学,太原030024 [3]中国科学院金属研究所,沈阳110016

出　　处：《表面技术》2024年第10期167-172,206,共7页Surface Technology

摘　　要：目的通过表面涂层提高γ-TiAl基合金的抗高温氧化性能。方法采用常规喷涂涂料法在γ-TiAl合金基体上制备Al_(2)O_(3)-SiC-AlPO_(4)磷酸盐复合抗高温氧化涂层。研究γ-TiAl合金和涂层样品在900℃、静态空气条件下的准等温氧化动力学行为。用XRD和SEM/EDS分别对涂层样品氧化前后的物相组成、组织形貌和微区成分进行表征分析;用电子探针(EPMA)分析涂层样品的元素分布情况。结果900℃恒温氧化动力学研究结果表明,γ-TiAl基合金初期氧化速率常数为32.501×10^(-2)mg/(cm^(2)·h^(1/2)),与后期氧化速率常数28.113×10^(-2)mg/(cm^(2)·h^(1/2))基本接近,呈直线规律,不具有抗氧化性能;而Al_(2)O_(3)-SiC-AlPO_(4)磷酸盐复合涂层样品氧化后期氧化速率常数为5.967×10^(-2) mg/(cm^(2)·h^(1/2)),与氧化初期8 h内氧化速率常数23.941×10^(-2) mg/(cm^(2)·h^(1/2))相比,明显降低,遵循典型抛物线规律,具有抗氧化性能。微观分析结果表明,原始涂层与γ-TiAl合金基体结合紧密,涂层主要相组成为Al_(2)O_(3)、SiC、SiO_(2);AlPO_(4)以无定形状态构成涂层连续相。氧化后,AlPO_(4)演变成晶态,形成涂层致密的网络结构;部分基体钛元素扩散进入涂层中疏松部位,氧化后形成TiO_(2)弥散分布在涂层中,填补了涂层疏松部位,使涂层更加致密;在涂层与基体界面2μm区域内形成连续致密Al_(2)O_(3)膜,阻挡了空气中的氧进一步扩散进入基体。结论Al_(2)O_(3)-SiC-AlPO_(4)复合涂层有效降低了γ-TiAl基合金氧化速率,有助于形成保护性Al_(2)O_(3)膜,明显改善了900℃γ-TiAl基合金抗高温氧化性能。γ-TiAl based alloys are considered as promising high temperature light-weight structural materials due to their high specific strengths and elastic moduli.However,through analyzing the phase diagram of the Ti-Al-O system,it can be seen that theγ-TiAl based alloys can not form protectiveα-Al_(2)O_(3) scale because of inadequate aluminum content in the alloy.Therefore,high temperature oxidation resistance coatings are still necessary to improve the anti-oxidation properties ofγ-TiAl alloys at temperature above 800℃.Traditional coatings for high temperature oxidation,such as MCrAlY,suffer from severe inter-diffusion between coatings and the substrate,which will cause negative effect on alloy mechanical properties.Other types of coatings developed wildly,such as CrAlN ceramics,halogenation Si.Phosphate coatings are also ideal oxidation resistance coatings for their high temperature stability up to 1400℃.In this work,Al_(2)O_(3)-SiC-AlPO_(4) composite phosphate coatings were designed and coated onγ-TiAl alloy substrate by conventional paint spraying method.The kinetic behavior of quasi-isotherm oxidation ofγ-TiAl alloy and coating samples were studied at 900℃under static air conditions.The physical phase composition,surface morphology and micro-zone composition of the coating samples before and after oxidation were characterized and analyzed by XRD and SEM/EDS,respectively.The element distribution of the coating samples were analyzed by electron probe(EPMA).The results of 900℃anti-temperature oxidation experiments showed that the oxidation rate constant ofγ-TiAl based alloy was 32.501×10^(-2) mg/(cm^(2)·h^(1/2))at early oxidation stage,which was close to the oxidation rate constant of 28.113×10^(-2) mg/(cm^(2)·h^(1/2))at late oxidation stage.This result indicated that the oxidation kinetics of theγ-TiAl based alloy followed straight line law,and the oxide scales of the bare alloy were not protective.The oxidation rate constant of Al_(2)O_(3)-SiC-AlPO_(4) composite coatings was 5.967×10^(-2) mg/(cm

关 键 词：Γ-TIAL基合金 抗高温氧化性能 磷酸盐涂层 氧化动力学 微观组织 

分 类 号：TG174[金属学及工艺—金属表面处理]